includes/libs/rdbms/database/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26 namespace Wikimedia\Rdbms;
  27
  28 use Psr\Log\LoggerAwareInterface;
  29 use Psr\Log\LoggerInterface;
  30 use Psr\Log\NullLogger;
  31 use Wikimedia\ScopedCallback;
  32 use Wikimedia\Timestamp\ConvertibleTimestamp;
  33 use Wikimedia\AtEase\AtEase;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41 use Throwable;
  42
  43 /**
  44  * Relational database abstraction object
  45  *
  46  * @ingroup Database
  47  * @since 1.28
  48  */
  49 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  50         /** @var string Server that this instance is currently connected to */
  51         protected $server;
  52         /** @var string User that this instance is currently connected under the name of */
  53         protected $user;
  54         /** @var string Password used to establish the current connection */
  55         protected $password;
  56         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  57         protected $tableAliases = [];
  58         /** @var string[] Map of (index alias => index) */
  59         protected $indexAliases = [];
  60         /** @var bool Whether this PHP instance is for a CLI script */
  61         protected $cliMode;
  62         /** @var string Agent name for query profiling */
  63         protected $agent;
  64         /** @var int Bit field of class DBO_* constants */
  65         protected $flags;
  66         /** @var array LoadBalancer tracking information */
  67         protected $lbInfo = [];
  68         /** @var array|bool Variables use for schema element placeholders */
  69         protected $schemaVars = false;
  70         /** @var array Parameters used by initConnection() to establish a connection */
  71         protected $connectionParams = [];
  72         /** @var array SQL variables values to use for all new connections */
  73         protected $connectionVariables = [];
  74         /** @var string Current SQL query delimiter */
  75         protected $delimiter = ';';
  76         /** @var string|bool|null Stashed value of html_errors INI setting */
  77         protected $htmlErrors;
  78         /** @var int Row batch size to use for emulated INSERT SELECT queries */
  79         protected $nonNativeInsertSelectBatchSize = 10000;
  80
  81         /** @var BagOStuff APC cache */
  82         protected $srvCache;
  83         /** @var LoggerInterface */
  84         protected $connLogger;
  85         /** @var LoggerInterface */
  86         protected $queryLogger;
  87         /** @var callable Error logging callback */
  88         protected $errorLogger;
  89         /** @var callable Deprecation logging callback */
  90         protected $deprecationLogger;
  91         /** @var callable|null */
  92         protected $profiler;
  93         /** @var TransactionProfiler */
  94         protected $trxProfiler;
  95         /** @var DatabaseDomain */
  96         protected $currentDomain;
  97         /** @var object|resource|null Database connection */
  98         protected $conn;
  99
 100         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 101         private $lazyMasterHandle;
 102
 103         /** @var array Map of (name => 1) for locks obtained via lock() */
 104         protected $sessionNamedLocks = [];
 105         /** @var array Map of (table name => 1) for TEMPORARY tables */
 106         protected $sessionTempTables = [];
 107
 108         /** @var string ID of the active transaction or the empty string otherwise */
 109         protected $trxShortId = '';
 110         /** @var int Transaction status */
 111         protected $trxStatus = self::STATUS_TRX_NONE;
 112         /** @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR */
 113         protected $trxStatusCause;
 114         /** @var array|null Error details of the last statement-only rollback */
 115         private $trxStatusIgnoredCause;
 116         /** @var float|null UNIX timestamp at the time of BEGIN for the last transaction */
 117         private $trxTimestamp = null;
 118         /** @var float Replication lag estimate at the time of BEGIN for the last transaction */
 119         private $trxReplicaLag = null;
 120         /** @var string Name of the function that start the last transaction */
 121         private $trxFname = null;
 122         /** @var bool Whether possible write queries were done in the last transaction started */
 123         private $trxDoneWrites = false;
 124         /** @var bool Whether the current transaction was started implicitly due to DBO_TRX */
 125         private $trxAutomatic = false;
 126         /** @var int Counter for atomic savepoint identifiers (reset with each transaction) */
 127         private $trxAtomicCounter = 0;
 128         /** @var array List of (name, unique ID, savepoint ID) for each active atomic section level */
 129         private $trxAtomicLevels = [];
 130         /** @var bool Whether the current transaction was started implicitly by startAtomic() */
 131         private $trxAutomaticAtomic = false;
 132         /** @var string[] Write query callers of the current transaction */
 133         private $trxWriteCallers = [];
 134         /** @var float Seconds spent in write queries for the current transaction */
 135         private $trxWriteDuration = 0.0;
 136         /** @var int Number of write queries for the current transaction */
 137         private $trxWriteQueryCount = 0;
 138         /** @var int Number of rows affected by write queries for the current transaction */
 139         private $trxWriteAffectedRows = 0;
 140         /** @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries */
 141         private $trxWriteAdjDuration = 0.0;
 142         /** @var int Number of write queries counted in trxWriteAdjDuration */
 143         private $trxWriteAdjQueryCount = 0;
 144         /** @var array[] List of (callable, method name, atomic section id) */
 145         private $trxIdleCallbacks = [];
 146         /** @var array[] List of (callable, method name, atomic section id) */
 147         private $trxPreCommitCallbacks = [];
 148         /** @var array[] List of (callable, method name, atomic section id) */
 149         private $trxEndCallbacks = [];
 150         /** @var array[] List of (callable, method name, atomic section id) */
 151         private $trxSectionCancelCallbacks = [];
 152         /** @var callable[] Map of (name => callable) */
 153         private $trxRecurringCallbacks = [];
 154         /** @var bool Whether to suppress triggering of transaction end callbacks */
 155         private $trxEndCallbacksSuppressed = false;
 156
 157         /** @var int[] Prior flags member variable values */
 158         private $priorFlags = [];
 159
 160         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 161         protected $affectedRowCount;
 162
 163         /** @var float UNIX timestamp */
 164         private $lastPing = 0.0;
 165         /** @var string The last SQL query attempted */
 166         private $lastQuery = '';
 167         /** @var float|bool UNIX timestamp of last write query */
 168         private $lastWriteTime = false;
 169         /** @var string|bool */
 170         private $lastPhpError = false;
 171         /** @var float Query rount trip time estimate */
 172         private $lastRoundTripEstimate = 0.0;
 173
 174         /** @var string Lock granularity is on the level of the entire database */
 175         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
 176         /** @var string The SCHEMA keyword refers to a grouping of tables in a database */
 177         const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';
 178
 179         /** @var int New Database instance will not be connected yet when returned */
 180         const NEW_UNCONNECTED = 0;
 181         /** @var int New Database instance will already be connected when returned */
 182         const NEW_CONNECTED = 1;
 183
 184         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 185         const STATUS_TRX_ERROR = 1;
 186         /** @var int Transaction is active and in a normal state */
 187         const STATUS_TRX_OK = 2;
 188         /** @var int No transaction is active */
 189         const STATUS_TRX_NONE = 3;
 190
 191         /** @var string Idiom used when a cancelable atomic section started the transaction */
 192         private static $NOT_APPLICABLE = 'n/a';
 193         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 194         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 195
 196         /** @var int Writes to this temporary table do not affect lastDoneWrites() */
 197         private static $TEMP_NORMAL = 1;
 198         /** @var int Writes to this temporary table effect lastDoneWrites() */
 199         private static $TEMP_PSEUDO_PERMANENT = 2;
 200
 201         /** @var int Number of times to re-try an operation in case of deadlock */
 202         private static $DEADLOCK_TRIES = 4;
 203         /** @var int Minimum time to wait before retry, in microseconds */
 204         private static $DEADLOCK_DELAY_MIN = 500000;
 205         /** @var int Maximum time to wait before retry */
 206         private static $DEADLOCK_DELAY_MAX = 1500000;
 207
 208         /** @var int How long before it is worth doing a dummy query to test the connection */
 209         private static $PING_TTL = 1.0;
 210         /** @var string Dummy SQL query */
 211         private static $PING_QUERY = 'SELECT 1 AS ping';
 212
 213         /** @var float Guess of how many seconds it takes to replicate a small insert */
 214         private static $TINY_WRITE_SEC = 0.010;
 215         /** @var float Consider a write slow if it took more than this many seconds */
 216         private static $SLOW_WRITE_SEC = 0.500;
 217         /** @var float Assume an insert of this many rows or less should be fast to replicate */
 218         private static $SMALL_WRITE_ROWS = 100;
 219
 220         /** @var string[] List of DBO_* flags that can be changed after connection */
 221         protected static $MUTABLE_FLAGS = [
 222                 'DBO_DEBUG',
 223                 'DBO_NOBUFFER',
 224                 'DBO_TRX',
 225                 'DBO_DDLMODE',
 226         ];
 227         /** @var int Bit field of all DBO_* flags that can be changed after connection */
 228         protected static $DBO_MUTABLE = (
 229                 self::DBO_DEBUG | self::DBO_NOBUFFER | self::DBO_TRX | self::DBO_DDLMODE
 230         );
 231
 232         /**
 233          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 234          * @param array $params Parameters passed from Database::factory()
 235          */
 236         protected function __construct( array $params ) {
 237                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 238                         $this->connectionParams[$name] = $params[$name];
 239                 }
 240
 241                 $this->cliMode = $params['cliMode'];
 242                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 243                 $this->agent = str_replace( '/', '-', $params['agent'] );
 244
 245                 $this->flags = $params['flags'];
 246                 if ( $this->flags & self::DBO_DEFAULT ) {
 247                         if ( $this->cliMode ) {
 248                                 $this->flags &= ~self::DBO_TRX;
 249                         } else {
 250                                 $this->flags |= self::DBO_TRX;
 251                         }
 252                 }
 253                 // Disregard deprecated DBO_IGNORE flag (T189999)
 254                 $this->flags &= ~self::DBO_IGNORE;
 255
 256                 $this->connectionVariables = $params['variables'];
 257
 258                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 259
 260                 $this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 261                 $this->trxProfiler = $params['trxProfiler'];
 262                 $this->connLogger = $params['connLogger'];
 263                 $this->queryLogger = $params['queryLogger'];
 264                 $this->errorLogger = $params['errorLogger'];
 265                 $this->deprecationLogger = $params['deprecationLogger'];
 266
 267                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 268                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 269                 }
 270
 271                 // Set initial dummy domain until open() sets the final DB/prefix
 272                 $this->currentDomain = new DatabaseDomain(
 273                         $params['dbname'] != '' ? $params['dbname'] : null,
 274                         $params['schema'] != '' ? $params['schema'] : null,
 275                         $params['tablePrefix']
 276                 );
 277         }
 278
 279         /**
 280          * Initialize the connection to the database over the wire (or to local files)
 281          *
 282          * @throws LogicException
 283          * @throws InvalidArgumentException
 284          * @throws DBConnectionError
 285          * @since 1.31
 286          */
 287         final public function initConnection() {
 288                 if ( $this->isOpen() ) {
 289                         throw new LogicException( __METHOD__ . ': already connected' );
 290                 }
 291                 // Establish the connection
 292                 $this->doInitConnection();
 293         }
 294
 295         /**
 296          * Actually connect to the database over the wire (or to local files)
 297          *
 298          * @throws DBConnectionError
 299          * @since 1.31
 300          */
 301         protected function doInitConnection() {
 302                 $this->open(
 303                         $this->connectionParams['host'],
 304                         $this->connectionParams['user'],
 305                         $this->connectionParams['password'],
 306                         $this->connectionParams['dbname'],
 307                         $this->connectionParams['schema'],
 308                         $this->connectionParams['tablePrefix']
 309                 );
 310         }
 311
 312         /**
 313          * Open a new connection to the database (closing any existing one)
 314          *
 315          * @param string|null $server Database server host
 316          * @param string|null $user Database user name
 317          * @param string|null $password Database user password
 318          * @param string|null $dbName Database name
 319          * @param string|null $schema Database schema name
 320          * @param string $tablePrefix Table prefix
 321          * @throws DBConnectionError
 322          */
 323         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 324
 325         /**
 326          * Construct a Database subclass instance given a database type and parameters
 327          *
 328          * This also connects to the database immediately upon object construction
 329          *
 330          * @param string $type A possible DB type (sqlite, mysql, postgres,...)
 331          * @param array $params Parameter map with keys:
 332          *   - host : The hostname of the DB server
 333          *   - user : The name of the database user the client operates under
 334          *   - password : The password for the database user
 335          *   - dbname : The name of the database to use where queries do not specify one.
 336          *      The database must exist or an error might be thrown. Setting this to the empty string
 337          *      will avoid any such errors and make the handle have no implicit database scope. This is
 338          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 339          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 340          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 341          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 342          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 343          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 344          *      recognized in queries. This can be used in place of schemas for handle site farms.
 345          *   - flags : Optional bit field of DBO_* constants that define connection, protocol,
 346          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 347          *      flag in place UNLESS this this database simply acts as a key/value store.
 348          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 349          *      'mysqli' driver; the old one 'mysql' has been removed.
 350          *   - variables: Optional map of session variables to set after connecting. This can be
 351          *      used to adjust lock timeouts or encoding modes and the like.
 352          *   - connLogger: Optional PSR-3 logger interface instance.
 353          *   - queryLogger: Optional PSR-3 logger interface instance.
 354          *   - profiler : Optional callback that takes a section name argument and returns
 355          *      a ScopedCallback instance that ends the profile section in its destructor.
 356          *      These will be called in query(), using a simplified version of the SQL that
 357          *      also includes the agent as a SQL comment.
 358          *   - trxProfiler: Optional TransactionProfiler instance.
 359          *   - errorLogger: Optional callback that takes an Exception and logs it.
 360          *   - deprecationLogger: Optional callback that takes a string and logs it.
 361          *   - cliMode: Whether to consider the execution context that of a CLI script.
 362          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 363          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 364          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 365          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 366          * @return Database|null If the database driver or extension cannot be found
 367          * @throws InvalidArgumentException If the database driver or extension cannot be found
 368          * @since 1.18
 369          */
 370         final public static function factory( $type, $params = [], $connect = self::NEW_CONNECTED ) {
 371                 $class = self::getClass( $type, $params['driver'] ?? null );
 372
 373                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 374                         $params += [
 375                                 'host' => null,
 376                                 'user' => null,
 377                                 'password' => null,
 378                                 'dbname' => null,
 379                                 'schema' => null,
 380                                 'tablePrefix' => '',
 381                                 'flags' => 0,
 382                                 'variables' => [],
 383                                 'cliMode' => ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' ),
 384                                 'agent' => basename( $_SERVER['SCRIPT_NAME'] ) . '@' . gethostname()
 385                         ];
 386
 387                         $normalizedParams = [
 388                                 // Configuration
 389                                 'host' => strlen( $params['host'] ) ? $params['host'] : null,
 390                                 'user' => strlen( $params['user'] ) ? $params['user'] : null,
 391                                 'password' => is_string( $params['password'] ) ? $params['password'] : null,
 392                                 'dbname' => strlen( $params['dbname'] ) ? $params['dbname'] : null,
 393                                 'schema' => strlen( $params['schema'] ) ? $params['schema'] : null,
 394                                 'tablePrefix' => (string)$params['tablePrefix'],
 395                                 'flags' => (int)$params['flags'],
 396                                 'variables' => $params['variables'],
 397                                 'cliMode' => (bool)$params['cliMode'],
 398                                 'agent' => (string)$params['agent'],
 399                                 // Objects and callbacks
 400                                 'profiler' => $params['profiler'] ?? null,
 401                                 'trxProfiler' => $params['trxProfiler'] ?? new TransactionProfiler(),
 402                                 'connLogger' => $params['connLogger'] ?? new NullLogger(),
 403                                 'queryLogger' => $params['queryLogger'] ?? new NullLogger(),
 404                                 'errorLogger' => $params['errorLogger'] ?? function ( Exception $e ) {
 405                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 406                                 },
 407                                 'deprecationLogger' => $params['deprecationLogger'] ?? function ( $msg ) {
 408                                         trigger_error( $msg, E_USER_DEPRECATED );
 409                                 }
 410                         ] + $params;
 411
 412                         /** @var Database $conn */
 413                         $conn = new $class( $normalizedParams );
 414                         if ( $connect === self::NEW_CONNECTED ) {
 415                                 $conn->initConnection();
 416                         }
 417                 } else {
 418                         $conn = null;
 419                 }
 420
 421                 return $conn;
 422         }
 423
 424         /**
 425          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 426          * @param string|null $driver Optional name of a specific DB client driver
 427          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 428          * @throws InvalidArgumentException
 429          * @since 1.31
 430          */
 431         final public static function attributesFromType( $dbType, $driver = null ) {
 432                 static $defaults = [
 433                         self::ATTR_DB_LEVEL_LOCKING => false,
 434                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 435                 ];
 436
 437                 $class = self::getClass( $dbType, $driver );
 438
 439                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 440         }
 441
 442         /**
 443          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 444          * @param string|null $driver Optional name of a specific DB client driver
 445          * @return string Database subclass name to use
 446          * @throws InvalidArgumentException
 447          */
 448         private static function getClass( $dbType, $driver = null ) {
 449                 // For database types with built-in support, the below maps type to IDatabase
 450                 // implementations. For types with multipe driver implementations (PHP extensions),
 451                 // an array can be used, keyed by extension name. In case of an array, the
 452                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 453                 // we auto-detect the first available driver. For types without built-in support,
 454                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 455                 static $builtinTypes = [
 456                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 457                         'sqlite' => DatabaseSqlite::class,
 458                         'postgres' => DatabasePostgres::class,
 459                 ];
 460
 461                 $dbType = strtolower( $dbType );
 462                 $class = false;
 463
 464                 if ( isset( $builtinTypes[$dbType] ) ) {
 465                         $possibleDrivers = $builtinTypes[$dbType];
 466                         if ( is_string( $possibleDrivers ) ) {
 467                                 $class = $possibleDrivers;
 468                         } elseif ( (string)$driver !== '' ) {
 469                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 470                                         throw new InvalidArgumentException( __METHOD__ .
 471                                                 " type '$dbType' does not support driver '{$driver}'" );
 472                                 }
 473
 474                                 $class = $possibleDrivers[$driver];
 475                         } else {
 476                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 477                                         if ( extension_loaded( $posDriver ) ) {
 478                                                 $class = $possibleClass;
 479                                                 break;
 480                                         }
 481                                 }
 482                         }
 483                 } else {
 484                         $class = 'Database' . ucfirst( $dbType );
 485                 }
 486
 487                 if ( $class === false ) {
 488                         throw new InvalidArgumentException( __METHOD__ .
 489                                 " no viable database extension found for type '$dbType'" );
 490                 }
 491
 492                 return $class;
 493         }
 494
 495         /**
 496          * @return array Map of (Database::ATTR_* constant => value
 497          * @since 1.31
 498          */
 499         protected static function getAttributes() {
 500                 return [];
 501         }
 502
 503         /**
 504          * Set the PSR-3 logger interface to use for query logging. (The logger
 505          * interfaces for connection logging and error logging can be set with the
 506          * constructor.)
 507          *
 508          * @param LoggerInterface $logger
 509          */
 510         public function setLogger( LoggerInterface $logger ) {
 511                 $this->queryLogger = $logger;
 512         }
 513
 514         public function getServerInfo() {
 515                 return $this->getServerVersion();
 516         }
 517
 518         public function bufferResults( $buffer = null ) {
 519                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 520                 if ( $buffer !== null ) {
 521                         $buffer
 522                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 523                                 : $this->setFlag( self::DBO_NOBUFFER );
 524                 }
 525
 526                 return $res;
 527         }
 528
 529         final public function trxLevel() {
 530                 return ( $this->trxShortId != '' ) ? 1 : 0;
 531         }
 532
 533         public function trxTimestamp() {
 534                 return $this->trxLevel() ? $this->trxTimestamp : null;
 535         }
 536
 537         /**
 538          * @return int One of the STATUS_TRX_* class constants
 539          * @since 1.31
 540          */
 541         public function trxStatus() {
 542                 return $this->trxStatus;
 543         }
 544
 545         public function tablePrefix( $prefix = null ) {
 546                 $old = $this->currentDomain->getTablePrefix();
 547                 if ( $prefix !== null ) {
 548                         $this->currentDomain = new DatabaseDomain(
 549                                 $this->currentDomain->getDatabase(),
 550                                 $this->currentDomain->getSchema(),
 551                                 $prefix
 552                         );
 553                 }
 554
 555                 return $old;
 556         }
 557
 558         public function dbSchema( $schema = null ) {
 559                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 560                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set" );
 561                 }
 562
 563                 $old = $this->currentDomain->getSchema();
 564                 if ( $schema !== null ) {
 565                         $this->currentDomain = new DatabaseDomain(
 566                                 $this->currentDomain->getDatabase(),
 567                                 // DatabaseDomain uses null for unspecified schemas
 568                                 strlen( $schema ) ? $schema : null,
 569                                 $this->currentDomain->getTablePrefix()
 570                         );
 571                 }
 572
 573                 return (string)$old;
 574         }
 575
 576         /**
 577          * @return string Schema to use to qualify relations in queries
 578          */
 579         protected function relationSchemaQualifier() {
 580                 return $this->dbSchema();
 581         }
 582
 583         public function getLBInfo( $name = null ) {
 584                 if ( is_null( $name ) ) {
 585                         return $this->lbInfo;
 586                 }
 587
 588                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 589                         return $this->lbInfo[$name];
 590                 }
 591
 592                 return null;
 593         }
 594
 595         public function setLBInfo( $nameOrArray, $value = null ) {
 596                 if ( is_array( $nameOrArray ) ) {
 597                         $this->lbInfo = $nameOrArray;
 598                 } elseif ( is_string( $nameOrArray ) ) {
 599                         if ( $value !== null ) {
 600                                 $this->lbInfo[$nameOrArray] = $value;
 601                         } else {
 602                                 unset( $this->lbInfo[$nameOrArray] );
 603                         }
 604                 } else {
 605                         throw new InvalidArgumentException( "Got non-string key" );
 606                 }
 607         }
 608
 609         public function setLazyMasterHandle( IDatabase $conn ) {
 610                 $this->lazyMasterHandle = $conn;
 611         }
 612
 613         /**
 614          * @return IDatabase|null
 615          * @see setLazyMasterHandle()
 616          * @since 1.27
 617          */
 618         protected function getLazyMasterHandle() {
 619                 return $this->lazyMasterHandle;
 620         }
 621
 622         public function implicitOrderby() {
 623                 return true;
 624         }
 625
 626         public function lastQuery() {
 627                 return $this->lastQuery;
 628         }
 629
 630         public function lastDoneWrites() {
 631                 return $this->lastWriteTime ?: false;
 632         }
 633
 634         public function writesPending() {
 635                 return $this->trxLevel() && $this->trxDoneWrites;
 636         }
 637
 638         public function writesOrCallbacksPending() {
 639                 return $this->trxLevel() && (
 640                         $this->trxDoneWrites ||
 641                         $this->trxIdleCallbacks ||
 642                         $this->trxPreCommitCallbacks ||
 643                         $this->trxEndCallbacks ||
 644                         $this->trxSectionCancelCallbacks
 645                 );
 646         }
 647
 648         public function preCommitCallbacksPending() {
 649                 return $this->trxLevel() && $this->trxPreCommitCallbacks;
 650         }
 651
 652         /**
 653          * @return string|null
 654          */
 655         final protected function getTransactionRoundId() {
 656                 // If transaction round participation is enabled, see if one is active
 657                 if ( $this->getFlag( self::DBO_TRX ) ) {
 658                         $id = $this->getLBInfo( 'trxRoundId' );
 659
 660                         return is_string( $id ) ? $id : null;
 661                 }
 662
 663                 return null;
 664         }
 665
 666         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 667                 if ( !$this->trxLevel() ) {
 668                         return false;
 669                 } elseif ( !$this->trxDoneWrites ) {
 670                         return 0.0;
 671                 }
 672
 673                 switch ( $type ) {
 674                         case self::ESTIMATE_DB_APPLY:
 675                                 return $this->pingAndCalculateLastTrxApplyTime();
 676                         default: // everything
 677                                 return $this->trxWriteDuration;
 678                 }
 679         }
 680
 681         /**
 682          * @return float Time to apply writes to replicas based on trxWrite* fields
 683          */
 684         private function pingAndCalculateLastTrxApplyTime() {
 685                 $this->ping( $rtt );
 686
 687                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 688                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 689                 // For omitted queries, make them count as something at least
 690                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 691                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 692
 693                 return $applyTime;
 694         }
 695
 696         public function pendingWriteCallers() {
 697                 return $this->trxLevel() ? $this->trxWriteCallers : [];
 698         }
 699
 700         public function pendingWriteRowsAffected() {
 701                 return $this->trxWriteAffectedRows;
 702         }
 703
 704         /**
 705          * List the methods that have write queries or callbacks for the current transaction
 706          *
 707          * This method should not be used outside of Database/LoadBalancer
 708          *
 709          * @return string[]
 710          * @since 1.32
 711          */
 712         public function pendingWriteAndCallbackCallers() {
 713                 $fnames = $this->pendingWriteCallers();
 714                 foreach ( [
 715                         $this->trxIdleCallbacks,
 716                         $this->trxPreCommitCallbacks,
 717                         $this->trxEndCallbacks,
 718                         $this->trxSectionCancelCallbacks
 719                 ] as $callbacks ) {
 720                         foreach ( $callbacks as $callback ) {
 721                                 $fnames[] = $callback[1];
 722                         }
 723                 }
 724
 725                 return $fnames;
 726         }
 727
 728         /**
 729          * @return string
 730          */
 731         private function flatAtomicSectionList() {
 732                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 733                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 734                 } );
 735         }
 736
 737         public function isOpen() {
 738                 return (bool)$this->conn;
 739         }
 740
 741         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 742                 if ( $flag & ~static::$DBO_MUTABLE ) {
 743                         throw new DBUnexpectedError(
 744                                 $this,
 745                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 746                         );
 747                 }
 748
 749                 if ( $remember === self::REMEMBER_PRIOR ) {
 750                         array_push( $this->priorFlags, $this->flags );
 751                 }
 752
 753                 $this->flags |= $flag;
 754         }
 755
 756         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 757                 if ( $flag & ~static::$DBO_MUTABLE ) {
 758                         throw new DBUnexpectedError(
 759                                 $this,
 760                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 761                         );
 762                 }
 763
 764                 if ( $remember === self::REMEMBER_PRIOR ) {
 765                         array_push( $this->priorFlags, $this->flags );
 766                 }
 767
 768                 $this->flags &= ~$flag;
 769         }
 770
 771         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 772                 if ( !$this->priorFlags ) {
 773                         return;
 774                 }
 775
 776                 if ( $state === self::RESTORE_INITIAL ) {
 777                         $this->flags = reset( $this->priorFlags );
 778                         $this->priorFlags = [];
 779                 } else {
 780                         $this->flags = array_pop( $this->priorFlags );
 781                 }
 782         }
 783
 784         public function getFlag( $flag ) {
 785                 return ( ( $this->flags & $flag ) === $flag );
 786         }
 787
 788         public function getDomainID() {
 789                 return $this->currentDomain->getId();
 790         }
 791
 792         /**
 793          * Get information about an index into an object
 794          * @param string $table Table name
 795          * @param string $index Index name
 796          * @param string $fname Calling function name
 797          * @return mixed Database-specific index description class or false if the index does not exist
 798          */
 799         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 800
 801         /**
 802          * Wrapper for addslashes()
 803          *
 804          * @param string $s String to be slashed.
 805          * @return string Slashed string.
 806          */
 807         abstract function strencode( $s );
 808
 809         /**
 810          * Set a custom error handler for logging errors during database connection
 811          */
 812         protected function installErrorHandler() {
 813                 $this->lastPhpError = false;
 814                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 815                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 816         }
 817
 818         /**
 819          * Restore the previous error handler and return the last PHP error for this DB
 820          *
 821          * @return bool|string
 822          */
 823         protected function restoreErrorHandler() {
 824                 restore_error_handler();
 825                 if ( $this->htmlErrors !== false ) {
 826                         ini_set( 'html_errors', $this->htmlErrors );
 827                 }
 828
 829                 return $this->getLastPHPError();
 830         }
 831
 832         /**
 833          * @return string|bool Last PHP error for this DB (typically connection errors)
 834          */
 835         protected function getLastPHPError() {
 836                 if ( $this->lastPhpError ) {
 837                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 838                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 839
 840                         return $error;
 841                 }
 842
 843                 return false;
 844         }
 845
 846         /**
 847          * Error handler for logging errors during database connection
 848          * This method should not be used outside of Database classes
 849          *
 850          * @param int $errno
 851          * @param string $errstr
 852          */
 853         public function connectionErrorLogger( $errno, $errstr ) {
 854                 $this->lastPhpError = $errstr;
 855         }
 856
 857         /**
 858          * Create a log context to pass to PSR-3 logger functions.
 859          *
 860          * @param array $extras Additional data to add to context
 861          * @return array
 862          */
 863         protected function getLogContext( array $extras = [] ) {
 864                 return array_merge(
 865                         [
 866                                 'db_server' => $this->server,
 867                                 'db_name' => $this->getDBname(),
 868                                 'db_user' => $this->user,
 869                         ],
 870                         $extras
 871                 );
 872         }
 873
 874         final public function close() {
 875                 $exception = null; // error to throw after disconnecting
 876
 877                 $wasOpen = (bool)$this->conn;
 878                 // This should mostly do nothing if the connection is already closed
 879                 if ( $this->conn ) {
 880                         // Roll back any dangling transaction first
 881                         if ( $this->trxLevel() ) {
 882                                 if ( $this->trxAtomicLevels ) {
 883                                         // Cannot let incomplete atomic sections be committed
 884                                         $levels = $this->flatAtomicSectionList();
 885                                         $exception = new DBUnexpectedError(
 886                                                 $this,
 887                                                 __METHOD__ . ": atomic sections $levels are still open"
 888                                         );
 889                                 } elseif ( $this->trxAutomatic ) {
 890                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 891                                         // (empty ones we can silently roll back)
 892                                         if ( $this->writesOrCallbacksPending() ) {
 893                                                 $exception = new DBUnexpectedError(
 894                                                         $this,
 895                                                         __METHOD__ .
 896                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)"
 897                                                 );
 898                                         }
 899                                 } else {
 900                                         // Manual transactions should have been committed or rolled
 901                                         // back, even if empty.
 902                                         $exception = new DBUnexpectedError(
 903                                                 $this,
 904                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})"
 905                                         );
 906                                 }
 907
 908                                 if ( $this->trxEndCallbacksSuppressed ) {
 909                                         $exception = $exception ?: new DBUnexpectedError(
 910                                                 $this,
 911                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit'
 912                                         );
 913                                 }
 914
 915                                 // Rollback the changes and run any callbacks as needed
 916                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 917                         }
 918
 919                         // Close the actual connection in the binding handle
 920                         $closed = $this->closeConnection();
 921                 } else {
 922                         $closed = true; // already closed; nothing to do
 923                 }
 924
 925                 $this->conn = null;
 926
 927                 // Throw any unexpected errors after having disconnected
 928                 if ( $exception instanceof Exception ) {
 929                         throw $exception;
 930                 }
 931
 932                 // Note that various subclasses call close() at the start of open(), which itself is
 933                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 934                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 935                 // will be executed after the reconnection step.
 936                 if ( $wasOpen ) {
 937                         // Sanity check that no callbacks are dangling
 938                         $fnames = $this->pendingWriteAndCallbackCallers();
 939                         if ( $fnames ) {
 940                                 throw new RuntimeException(
 941                                         "Transaction callbacks are still pending: " . implode( ', ', $fnames )
 942                                 );
 943                         }
 944                 }
 945
 946                 return $closed;
 947         }
 948
 949         /**
 950          * Make sure there is an open connection handle (alive or not) as a sanity check
 951          *
 952          * This guards against fatal errors to the binding handle not being defined
 953          * in cases where open() was never called or close() was already called
 954          *
 955          * @throws DBUnexpectedError
 956          */
 957         final protected function assertHasConnectionHandle() {
 958                 if ( !$this->isOpen() ) {
 959                         throw new DBUnexpectedError( $this, "DB connection was already closed" );
 960                 }
 961         }
 962
 963         /**
 964          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 965          *
 966          * @throws DBReadOnlyRoleError
 967          * @throws DBReadOnlyError
 968          */
 969         protected function assertIsWritableMaster() {
 970                 if ( $this->getLBInfo( 'replica' ) === true ) {
 971                         throw new DBReadOnlyRoleError(
 972                                 $this,
 973                                 'Write operations are not allowed on replica database connections'
 974                         );
 975                 }
 976                 $reason = $this->getReadOnlyReason();
 977                 if ( $reason !== false ) {
 978                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 979                 }
 980         }
 981
 982         /**
 983          * Closes underlying database connection
 984          * @since 1.20
 985          * @return bool Whether connection was closed successfully
 986          */
 987         abstract protected function closeConnection();
 988
 989         /**
 990          * Run a query and return a DBMS-dependent wrapper or boolean
 991          *
 992          * This is meant to handle the basic command of actually sending a query to the
 993          * server via the driver. No implicit transaction, reconnection, nor retry logic
 994          * should happen here. The higher level query() method is designed to handle those
 995          * sorts of concerns. This method should not trigger such higher level methods.
 996          *
 997          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 998          * if any, occured during the last call to this method. Methods like executeQuery(),
 999          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
1000          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
1001          * meaningfully reflects any error that occured during that public query method call.
1002          *
1003          * For SELECT queries, this returns either:
1004          *   - a) A driver-specific value/resource, only on success. This can be iterated
1005          *        over by calling fetchObject()/fetchRow() until there are no more rows.
1006          *        Alternatively, the result can be passed to resultObject() to obtain an
1007          *        IResultWrapper instance which can then be iterated over via "foreach".
1008          *   - b) False, on any query failure
1009          *
1010          * For non-SELECT queries, this returns either:
1011          *   - a) A driver-specific value/resource, only on success
1012          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1013          *   - c) False, on any query failure
1014          *
1015          * @param string $sql SQL query
1016          * @return mixed|bool An object, resource, or true on success; false on failure
1017          */
1018         abstract protected function doQuery( $sql );
1019
1020         /**
1021          * Determine whether a query writes to the DB. When in doubt, this returns true.
1022          *
1023          * Main use cases:
1024          *
1025          * - Subsequent web requests should not need to wait for replication from
1026          *   the master position seen by this web request, unless this request made
1027          *   changes to the master. This is handled by ChronologyProtector by checking
1028          *   doneWrites() at the end of the request. doneWrites() returns true if any
1029          *   query set lastWriteTime; which query() does based on isWriteQuery().
1030          *
1031          * - Reject write queries to replica DBs, in query().
1032          *
1033          * @param string $sql
1034          * @return bool
1035          */
1036         protected function isWriteQuery( $sql ) {
1037                 // BEGIN and COMMIT queries are considered read queries here.
1038                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1039                 // treat these as write queries, in that their results have "affected rows"
1040                 // as meta data as from writes, instead of "num rows" as from reads.
1041                 // But, we treat them as read queries because when reading data (from
1042                 // either replica or master) we use transactions to enable repeatable-read
1043                 // snapshots, which ensures we get consistent results from the same snapshot
1044                 // for all queries within a request. Use cases:
1045                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1046                 // - We use this method to reject writes to replicas, but we need to allow
1047                 //   use of transactions on replicas for read snapshots. This is fine given
1048                 //   that transactions by themselves don't make changes, only actual writes
1049                 //   within the transaction matter, which we still detect.
1050                 return !preg_match(
1051                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1052                         $sql
1053                 );
1054         }
1055
1056         /**
1057          * @param string $sql
1058          * @return string|null
1059          */
1060         protected function getQueryVerb( $sql ) {
1061                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1062         }
1063
1064         /**
1065          * Determine whether a SQL statement is sensitive to isolation level.
1066          *
1067          * A SQL statement is considered transactable if its result could vary
1068          * depending on the transaction isolation level. Operational commands
1069          * such as 'SET' and 'SHOW' are not considered to be transactable.
1070          *
1071          * Main purpose: Used by query() to decide whether to begin a transaction
1072          * before the current query (in DBO_TRX mode, on by default).
1073          *
1074          * @param string $sql
1075          * @return bool
1076          */
1077         protected function isTransactableQuery( $sql ) {
1078                 return !in_array(
1079                         $this->getQueryVerb( $sql ),
1080                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
1081                         true
1082                 );
1083         }
1084
1085         /**
1086          * @param string $sql A SQL query
1087          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1088          * @return array A n-tuple of:
1089          *   - int|null: A self::TEMP_* constant for temp table operations or null otherwise
1090          *   - string|null: The name of the new temporary table $sql creates, or null
1091          *   - string|null: The name of the temporary table that $sql drops, or null
1092          */
1093         protected function getTempWrites( $sql, $pseudoPermanent ) {
1094                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1095
1096                 if ( preg_match(
1097                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1098                         $sql,
1099                         $matches
1100                 ) ) {
1101                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1102
1103                         return [ $type, $matches[1], null ];
1104                 } elseif ( preg_match(
1105                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1106                         $sql,
1107                         $matches
1108                 ) ) {
1109                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, $matches[1] ];
1110                 } elseif ( preg_match(
1111                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1112                         $sql,
1113                         $matches
1114                 ) ) {
1115                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1116                 } elseif ( preg_match(
1117                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1118                         $sql,
1119                         $matches
1120                 ) ) {
1121                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1122                 }
1123
1124                 return [ null, null, null ];
1125         }
1126
1127         /**
1128          * @param IResultWrapper|bool $ret
1129          * @param int|null $tmpType TEMP_NORMAL or TEMP_PSEUDO_PERMANENT
1130          * @param string|null $tmpNew Name of created temp table
1131          * @param string|null $tmpDel Name of dropped temp table
1132          */
1133         protected function registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel ) {
1134                 if ( $ret !== false ) {
1135                         if ( $tmpNew !== null ) {
1136                                 $this->sessionTempTables[$tmpNew] = $tmpType;
1137                         }
1138                         if ( $tmpDel !== null ) {
1139                                 unset( $this->sessionTempTables[$tmpDel] );
1140                         }
1141                 }
1142         }
1143
1144         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1145                 $flags = (int)$flags; // b/c; this field used to be a bool
1146                 // Sanity check that the SQL query is appropriate in the current context and is
1147                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1148                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1149
1150                 // Send the query to the server and fetch any corresponding errors
1151                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1152                 if ( $ret === false ) {
1153                         $ignoreErrors = $this->hasFlags( $flags, self::QUERY_SILENCE_ERRORS );
1154                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1155                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1156                 }
1157
1158                 return $this->resultObject( $ret );
1159         }
1160
1161         /**
1162          * Execute a query, retrying it if there is a recoverable connection loss
1163          *
1164          * This is similar to query() except:
1165          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1166          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1167          *   - It does not throw exceptions for common error cases
1168          *
1169          * This is meant for internal use with Database subclasses.
1170          *
1171          * @param string $sql Original SQL query
1172          * @param string $fname Name of the calling function
1173          * @param int $flags Bit field of class QUERY_* constants
1174          * @return array An n-tuple of:
1175          *   - mixed|bool: An object, resource, or true on success; false on failure
1176          *   - string: The result of calling lastError()
1177          *   - int: The result of calling lastErrno()
1178          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1179          * @throws DBUnexpectedError
1180          */
1181         final protected function executeQuery( $sql, $fname, $flags ) {
1182                 $this->assertHasConnectionHandle();
1183
1184                 $priorTransaction = $this->trxLevel();
1185
1186                 if ( $this->isWriteQuery( $sql ) ) {
1187                         // In theory, non-persistent writes are allowed in read-only mode, but due to things
1188                         // like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1189                         $this->assertIsWritableMaster();
1190                         // Do not treat temporary table writes as "meaningful writes" since they are only
1191                         // visible to one session and are not permanent. Profile them as reads. Integration
1192                         // tests can override this behavior via $flags.
1193                         $pseudoPermanent = $this->hasFlags( $flags, self::QUERY_PSEUDO_PERMANENT );
1194                         list( $tmpType, $tmpNew, $tmpDel ) = $this->getTempWrites( $sql, $pseudoPermanent );
1195                         $isPermWrite = ( $tmpType !== self::$TEMP_NORMAL );
1196                         // DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1197                         if ( $isPermWrite && $this->hasFlags( $flags, self::QUERY_REPLICA_ROLE ) ) {
1198                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1199                         }
1200                 } else {
1201                         // No permanent writes in this query
1202                         $isPermWrite = false;
1203                         // No temporary tables written to either
1204                         list( $tmpType, $tmpNew, $tmpDel ) = [ null, null, null ];
1205                 }
1206
1207                 // Add trace comment to the begin of the sql string, right after the operator.
1208                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1209                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1210
1211                 // Send the query to the server and fetch any corresponding errors.
1212                 // This also doubles as a "ping" to see if the connection was dropped.
1213                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1214                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1215
1216                 // Check if the query failed due to a recoverable connection loss
1217                 $allowRetry = !$this->hasFlags( $flags, self::QUERY_NO_RETRY );
1218                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1219                         // Silently resend the query to the server since it is safe and possible
1220                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1221                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1222                 }
1223
1224                 // Register creation and dropping of temporary tables
1225                 $this->registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel );
1226
1227                 $corruptedTrx = false;
1228
1229                 if ( $ret === false ) {
1230                         if ( $priorTransaction ) {
1231                                 if ( $recoverableSR ) {
1232                                         # We're ignoring an error that caused just the current query to be aborted.
1233                                         # But log the cause so we can log a deprecation notice if a caller actually
1234                                         # does ignore it.
1235                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1236                                 } elseif ( !$recoverableCL ) {
1237                                         # Either the query was aborted or all queries after BEGIN where aborted.
1238                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1239                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1240                                         # option is ROLLBACK, since the snapshots would have been released.
1241                                         $corruptedTrx = true; // cannot recover
1242                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1243                                         $this->trxStatusCause =
1244                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1245                                         $this->trxStatusIgnoredCause = null;
1246                                 }
1247                         }
1248                 }
1249
1250                 return [ $ret, $err, $errno, $corruptedTrx ];
1251         }
1252
1253         /**
1254          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1255          * tracking, and reconnects (without retry) on query failure due to connection loss
1256          *
1257          * @param string $sql Original SQL query
1258          * @param string $commentedSql SQL query with debugging/trace comment
1259          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1260          * @param string $fname Name of the calling function
1261          * @param int $flags Bit field of class QUERY_* constants
1262          * @return array An n-tuple of:
1263          *   - mixed|bool: An object, resource, or true on success; false on failure
1264          *   - string: The result of calling lastError()
1265          *   - int: The result of calling lastErrno()
1266          *       - bool: Whether a statement rollback error occured
1267          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1268          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1269          * @throws DBUnexpectedError
1270          */
1271         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1272                 $priorWritesPending = $this->writesOrCallbacksPending();
1273
1274                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1275                         $this->beginIfImplied( $sql, $fname );
1276                 }
1277
1278                 // Keep track of whether the transaction has write queries pending
1279                 if ( $isPermWrite ) {
1280                         $this->lastWriteTime = microtime( true );
1281                         if ( $this->trxLevel() && !$this->trxDoneWrites ) {
1282                                 $this->trxDoneWrites = true;
1283                                 $this->trxProfiler->transactionWritingIn(
1284                                         $this->server, $this->getDomainID(), $this->trxShortId );
1285                         }
1286                 }
1287
1288                 $prefix = !is_null( $this->getLBInfo( 'master' ) ) ? 'query-m: ' : 'query: ';
1289                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1290
1291                 $startTime = microtime( true );
1292                 $ps = $this->profiler
1293                         ? ( $this->profiler )( $generalizedSql->stringify() )
1294                         : null;
1295                 $this->affectedRowCount = null;
1296                 $this->lastQuery = $sql;
1297                 $ret = $this->doQuery( $commentedSql );
1298                 $lastError = $this->lastError();
1299                 $lastErrno = $this->lastErrno();
1300
1301                 $this->affectedRowCount = $this->affectedRows();
1302                 unset( $ps ); // profile out (if set)
1303                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1304
1305                 $recoverableSR = false; // recoverable statement rollback?
1306                 $recoverableCL = false; // recoverable connection loss?
1307                 $reconnected = false; // reconnection both attempted and succeeded?
1308
1309                 if ( $ret !== false ) {
1310                         $this->lastPing = $startTime;
1311                         if ( $isPermWrite && $this->trxLevel() ) {
1312                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1313                                 $this->trxWriteCallers[] = $fname;
1314                         }
1315                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1316                         # Check if no meaningful session state was lost
1317                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1318                         # Update session state tracking and try to restore the connection
1319                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1320                 } else {
1321                         # Check if only the last query was rolled back
1322                         $recoverableSR = $this->wasKnownStatementRollbackError();
1323                 }
1324
1325                 if ( $sql === self::$PING_QUERY ) {
1326                         $this->lastRoundTripEstimate = $queryRuntime;
1327                 }
1328
1329                 $this->trxProfiler->recordQueryCompletion(
1330                         $generalizedSql,
1331                         $startTime,
1332                         $isPermWrite,
1333                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1334                 );
1335
1336                 // Avoid the overhead of logging calls unless debug mode is enabled
1337                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1338                         $this->queryLogger->debug(
1339                                 "{method} [{runtime}s] {db_host}: $sql",
1340                                 [
1341                                         'method' => $fname,
1342                                         'db_host' => $this->getServer(),
1343                                         'domain' => $this->getDomainID(),
1344                                         'runtime' => round( $queryRuntime, 3 )
1345                                 ]
1346                         );
1347                 }
1348
1349                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1350         }
1351
1352         /**
1353          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1354          *
1355          * @param string $sql
1356          * @param string $fname
1357          */
1358         private function beginIfImplied( $sql, $fname ) {
1359                 if (
1360                         !$this->trxLevel() &&
1361                         $this->getFlag( self::DBO_TRX ) &&
1362                         $this->isTransactableQuery( $sql )
1363                 ) {
1364                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1365                         $this->trxAutomatic = true;
1366                 }
1367         }
1368
1369         /**
1370          * Update the estimated run-time of a query, not counting large row lock times
1371          *
1372          * LoadBalancer can be set to rollback transactions that will create huge replication
1373          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1374          * queries, like inserting a row can take a long time due to row locking. This method
1375          * uses some simple heuristics to discount those cases.
1376          *
1377          * @param string $sql A SQL write query
1378          * @param float $runtime Total runtime, including RTT
1379          * @param int $affected Affected row count
1380          */
1381         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1382                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1383                 $indicativeOfReplicaRuntime = true;
1384                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1385                         $verb = $this->getQueryVerb( $sql );
1386                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1387                         if ( $verb === 'INSERT' ) {
1388                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1389                         } elseif ( $verb === 'REPLACE' ) {
1390                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1391                         }
1392                 }
1393
1394                 $this->trxWriteDuration += $runtime;
1395                 $this->trxWriteQueryCount += 1;
1396                 $this->trxWriteAffectedRows += $affected;
1397                 if ( $indicativeOfReplicaRuntime ) {
1398                         $this->trxWriteAdjDuration += $runtime;
1399                         $this->trxWriteAdjQueryCount += 1;
1400                 }
1401         }
1402
1403         /**
1404          * Error out if the DB is not in a valid state for a query via query()
1405          *
1406          * @param string $sql
1407          * @param string $fname
1408          * @throws DBTransactionStateError
1409          */
1410         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1411                 $verb = $this->getQueryVerb( $sql );
1412                 if ( $verb === 'USE' ) {
1413                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead" );
1414                 }
1415
1416                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1417                         return;
1418                 }
1419
1420                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1421                         throw new DBTransactionStateError(
1422                                 $this,
1423                                 "Cannot execute query from $fname while transaction status is ERROR",
1424                                 [],
1425                                 $this->trxStatusCause
1426                         );
1427                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1428                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1429                         call_user_func( $this->deprecationLogger,
1430                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1431                                 "[$iLastErrno] $iLastError"
1432                         );
1433                         $this->trxStatusIgnoredCause = null;
1434                 }
1435         }
1436
1437         public function assertNoOpenTransactions() {
1438                 if ( $this->explicitTrxActive() ) {
1439                         throw new DBTransactionError(
1440                                 $this,
1441                                 "Explicit transaction still active. A caller may have caught an error. "
1442                                 . "Open transactions: " . $this->flatAtomicSectionList()
1443                         );
1444                 }
1445         }
1446
1447         /**
1448          * Determine whether it is safe to retry queries after a database connection is lost
1449          *
1450          * @param string $sql SQL query
1451          * @param bool $priorWritesPending Whether there is a transaction open with
1452          *     possible write queries or transaction pre-commit/idle callbacks
1453          *     waiting on it to finish.
1454          * @return bool True if it is safe to retry the query, false otherwise
1455          */
1456         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1457                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1458                 # Dropped connections also mean that named locks are automatically released.
1459                 # Only allow error suppression in autocommit mode or when the lost transaction
1460                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1461                 if ( $this->sessionNamedLocks ) {
1462                         return false; // possible critical section violation
1463                 } elseif ( $this->sessionTempTables ) {
1464                         return false; // tables might be queried latter
1465                 } elseif ( $sql === 'COMMIT' ) {
1466                         return !$priorWritesPending; // nothing written anyway? (T127428)
1467                 } elseif ( $sql === 'ROLLBACK' ) {
1468                         return true; // transaction lost...which is also what was requested :)
1469                 } elseif ( $this->explicitTrxActive() ) {
1470                         return false; // don't drop atomocity and explicit snapshots
1471                 } elseif ( $priorWritesPending ) {
1472                         return false; // prior writes lost from implicit transaction
1473                 }
1474
1475                 return true;
1476         }
1477
1478         /**
1479          * Clean things up after session (and thus transaction) loss before reconnect
1480          */
1481         private function handleSessionLossPreconnect() {
1482                 // Clean up tracking of session-level things...
1483                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1484                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1485                 $this->sessionTempTables = [];
1486                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1487                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1488                 $this->sessionNamedLocks = [];
1489                 // Session loss implies transaction loss
1490                 $oldTrxShortId = $this->consumeTrxShortId();
1491                 $this->trxAtomicCounter = 0;
1492                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1493                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1494                 // @note: leave trxRecurringCallbacks in place
1495                 if ( $this->trxDoneWrites ) {
1496                         $this->trxProfiler->transactionWritingOut(
1497                                 $this->server,
1498                                 $this->getDomainID(),
1499                                 $oldTrxShortId,
1500                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1501                                 $this->trxWriteAffectedRows
1502                         );
1503                 }
1504         }
1505
1506         /**
1507          * Clean things up after session (and thus transaction) loss after reconnect
1508          */
1509         private function handleSessionLossPostconnect() {
1510                 try {
1511                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1512                         // If callback suppression is set then the array will remain unhandled.
1513                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1514                 } catch ( Exception $ex ) {
1515                         // Already logged; move on...
1516                 }
1517                 try {
1518                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1519                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1520                 } catch ( Exception $ex ) {
1521                         // Already logged; move on...
1522                 }
1523         }
1524
1525         /**
1526          * Reset the transaction ID and return the old one
1527          *
1528          * @return string The old transaction ID or the empty string if there wasn't one
1529          */
1530         private function consumeTrxShortId() {
1531                 $old = $this->trxShortId;
1532                 $this->trxShortId = '';
1533
1534                 return $old;
1535         }
1536
1537         /**
1538          * Checks whether the cause of the error is detected to be a timeout.
1539          *
1540          * It returns false by default, and not all engines support detecting this yet.
1541          * If this returns false, it will be treated as a generic query error.
1542          *
1543          * @param string $error Error text
1544          * @param int $errno Error number
1545          * @return bool
1546          */
1547         protected function wasQueryTimeout( $error, $errno ) {
1548                 return false;
1549         }
1550
1551         /**
1552          * Report a query error. Log the error, and if neither the object ignore
1553          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1554          *
1555          * @param string $error
1556          * @param int $errno
1557          * @param string $sql
1558          * @param string $fname
1559          * @param bool $ignore
1560          * @throws DBQueryError
1561          */
1562         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1563                 if ( $ignore ) {
1564                         $this->queryLogger->debug( "SQL ERROR (ignored): $error" );
1565                 } else {
1566                         throw $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1567                 }
1568         }
1569
1570         /**
1571          * @param string $error
1572          * @param string|int $errno
1573          * @param string $sql
1574          * @param string $fname
1575          * @return DBError
1576          */
1577         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1578                 $this->queryLogger->error(
1579                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1580                         $this->getLogContext( [
1581                                 'method' => __METHOD__,
1582                                 'errno' => $errno,
1583                                 'error' => $error,
1584                                 'sql1line' => mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 ),
1585                                 'fname' => $fname,
1586                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1587                         ] )
1588                 );
1589
1590                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1591                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1592                 } elseif ( $this->wasConnectionError( $errno ) ) {
1593                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1594                 } else {
1595                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1596                 }
1597
1598                 return $e;
1599         }
1600
1601         /**
1602          * @param string $error
1603          * @return DBConnectionError
1604          */
1605         final protected function newExceptionAfterConnectError( $error ) {
1606                 // Connection was not fully initialized and is not safe for use
1607                 $this->conn = null;
1608
1609                 $this->connLogger->error(
1610                         "Error connecting to {db_server} as user {db_user}: {error}",
1611                         $this->getLogContext( [
1612                                 'error' => $error,
1613                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1614                         ] )
1615                 );
1616
1617                 return new DBConnectionError( $this, $error );
1618         }
1619
1620         public function freeResult( $res ) {
1621         }
1622
1623         public function selectField(
1624                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1625         ) {
1626                 if ( $var === '*' ) { // sanity
1627                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1628                 }
1629
1630                 if ( !is_array( $options ) ) {
1631                         $options = [ $options ];
1632                 }
1633
1634                 $options['LIMIT'] = 1;
1635
1636                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1637                 if ( $res === false ) {
1638                         throw new DBUnexpectedError( $this, "Got false from select()" );
1639                 }
1640
1641                 $row = $this->fetchRow( $res );
1642                 if ( $row === false ) {
1643                         return false;
1644                 }
1645
1646                 return reset( $row );
1647         }
1648
1649         public function selectFieldValues(
1650                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1651         ) {
1652                 if ( $var === '*' ) { // sanity
1653                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1654                 } elseif ( !is_string( $var ) ) { // sanity
1655                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1656                 }
1657
1658                 if ( !is_array( $options ) ) {
1659                         $options = [ $options ];
1660                 }
1661
1662                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1663                 if ( $res === false ) {
1664                         throw new DBUnexpectedError( $this, "Got false from select()" );
1665                 }
1666
1667                 $values = [];
1668                 foreach ( $res as $row ) {
1669                         $values[] = $row->value;
1670                 }
1671
1672                 return $values;
1673         }
1674
1675         /**
1676          * Returns an optional USE INDEX clause to go after the table, and a
1677          * string to go at the end of the query.
1678          *
1679          * @param array $options Associative array of options to be turned into
1680          *   an SQL query, valid keys are listed in the function.
1681          * @return array
1682          * @see Database::select()
1683          */
1684         protected function makeSelectOptions( $options ) {
1685                 $preLimitTail = $postLimitTail = '';
1686                 $startOpts = '';
1687
1688                 $noKeyOptions = [];
1689
1690                 foreach ( $options as $key => $option ) {
1691                         if ( is_numeric( $key ) ) {
1692                                 $noKeyOptions[$option] = true;
1693                         }
1694                 }
1695
1696                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1697
1698                 $preLimitTail .= $this->makeOrderBy( $options );
1699
1700                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1701                         $postLimitTail .= ' FOR UPDATE';
1702                 }
1703
1704                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1705                         $postLimitTail .= ' LOCK IN SHARE MODE';
1706                 }
1707
1708                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1709                         $startOpts .= 'DISTINCT';
1710                 }
1711
1712                 # Various MySQL extensions
1713                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1714                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1715                 }
1716
1717                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1718                         $startOpts .= ' SQL_BIG_RESULT';
1719                 }
1720
1721                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1722                         $startOpts .= ' SQL_BUFFER_RESULT';
1723                 }
1724
1725                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1726                         $startOpts .= ' SQL_SMALL_RESULT';
1727                 }
1728
1729                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1730                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1731                 }
1732
1733                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1734                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1735                 } else {
1736                         $useIndex = '';
1737                 }
1738                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1739                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1740                 } else {
1741                         $ignoreIndex = '';
1742                 }
1743
1744                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1745         }
1746
1747         /**
1748          * Returns an optional GROUP BY with an optional HAVING
1749          *
1750          * @param array $options Associative array of options
1751          * @return string
1752          * @see Database::select()
1753          * @since 1.21
1754          */
1755         protected function makeGroupByWithHaving( $options ) {
1756                 $sql = '';
1757                 if ( isset( $options['GROUP BY'] ) ) {
1758                         $gb = is_array( $options['GROUP BY'] )
1759                                 ? implode( ',', $options['GROUP BY'] )
1760                                 : $options['GROUP BY'];
1761                         $sql .= ' GROUP BY ' . $gb;
1762                 }
1763                 if ( isset( $options['HAVING'] ) ) {
1764                         $having = is_array( $options['HAVING'] )
1765                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1766                                 : $options['HAVING'];
1767                         $sql .= ' HAVING ' . $having;
1768                 }
1769
1770                 return $sql;
1771         }
1772
1773         /**
1774          * Returns an optional ORDER BY
1775          *
1776          * @param array $options Associative array of options
1777          * @return string
1778          * @see Database::select()
1779          * @since 1.21
1780          */
1781         protected function makeOrderBy( $options ) {
1782                 if ( isset( $options['ORDER BY'] ) ) {
1783                         $ob = is_array( $options['ORDER BY'] )
1784                                 ? implode( ',', $options['ORDER BY'] )
1785                                 : $options['ORDER BY'];
1786
1787                         return ' ORDER BY ' . $ob;
1788                 }
1789
1790                 return '';
1791         }
1792
1793         public function select(
1794                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1795         ) {
1796                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1797
1798                 return $this->query( $sql, $fname );
1799         }
1800
1801         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1802                 $options = [], $join_conds = []
1803         ) {
1804                 if ( is_array( $vars ) ) {
1805                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1806                 } else {
1807                         $fields = $vars;
1808                 }
1809
1810                 $options = (array)$options;
1811                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1812                         ? $options['USE INDEX']
1813                         : [];
1814                 $ignoreIndexes = (
1815                         isset( $options['IGNORE INDEX'] ) &&
1816                         is_array( $options['IGNORE INDEX'] )
1817                 )
1818                         ? $options['IGNORE INDEX']
1819                         : [];
1820
1821                 if (
1822                         $this->selectOptionsIncludeLocking( $options ) &&
1823                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1824                 ) {
1825                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1826                         // functions. Discourage use of such queries to encourage compatibility.
1827                         call_user_func(
1828                                 $this->deprecationLogger,
1829                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)"
1830                         );
1831                 }
1832
1833                 if ( is_array( $table ) ) {
1834                         $from = ' FROM ' .
1835                                 $this->tableNamesWithIndexClauseOrJOIN(
1836                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1837                 } elseif ( $table != '' ) {
1838                         $from = ' FROM ' .
1839                                 $this->tableNamesWithIndexClauseOrJOIN(
1840                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1841                 } else {
1842                         $from = '';
1843                 }
1844
1845                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1846                         $this->makeSelectOptions( $options );
1847
1848                 if ( is_array( $conds ) ) {
1849                         $conds = $this->makeList( $conds, self::LIST_AND );
1850                 }
1851
1852                 if ( $conds === null || $conds === false ) {
1853                         $this->queryLogger->warning(
1854                                 __METHOD__
1855                                 . ' called from '
1856                                 . $fname
1857                                 . ' with incorrect parameters: $conds must be a string or an array'
1858                         );
1859                         $conds = '';
1860                 }
1861
1862                 if ( $conds === '' || $conds === '*' ) {
1863                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1864                 } elseif ( is_string( $conds ) ) {
1865                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1866                                 "WHERE $conds $preLimitTail";
1867                 } else {
1868                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1869                 }
1870
1871                 if ( isset( $options['LIMIT'] ) ) {
1872                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1873                                 $options['OFFSET'] ?? false );
1874                 }
1875                 $sql = "$sql $postLimitTail";
1876
1877                 if ( isset( $options['EXPLAIN'] ) ) {
1878                         $sql = 'EXPLAIN ' . $sql;
1879                 }
1880
1881                 return $sql;
1882         }
1883
1884         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1885                 $options = [], $join_conds = []
1886         ) {
1887                 $options = (array)$options;
1888                 $options['LIMIT'] = 1;
1889
1890                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1891                 if ( $res === false ) {
1892                         throw new DBUnexpectedError( $this, "Got false from select()" );
1893                 }
1894
1895                 if ( !$this->numRows( $res ) ) {
1896                         return false;
1897                 }
1898
1899                 return $this->fetchObject( $res );
1900         }
1901
1902         public function estimateRowCount(
1903                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1904         ) {
1905                 $conds = $this->normalizeConditions( $conds, $fname );
1906                 $column = $this->extractSingleFieldFromList( $var );
1907                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1908                         $conds[] = "$column IS NOT NULL";
1909                 }
1910
1911                 $res = $this->select(
1912                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1913                 );
1914                 $row = $res ? $this->fetchRow( $res ) : [];
1915
1916                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1917         }
1918
1919         public function selectRowCount(
1920                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1921         ) {
1922                 $conds = $this->normalizeConditions( $conds, $fname );
1923                 $column = $this->extractSingleFieldFromList( $var );
1924                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1925                         $conds[] = "$column IS NOT NULL";
1926                 }
1927
1928                 $res = $this->select(
1929                         [
1930                                 'tmp_count' => $this->buildSelectSubquery(
1931                                         $tables,
1932                                         '1',
1933                                         $conds,
1934                                         $fname,
1935                                         $options,
1936                                         $join_conds
1937                                 )
1938                         ],
1939                         [ 'rowcount' => 'COUNT(*)' ],
1940                         [],
1941                         $fname
1942                 );
1943                 $row = $res ? $this->fetchRow( $res ) : [];
1944
1945                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1946         }
1947
1948         /**
1949          * @param string|array $options
1950          * @return bool
1951          */
1952         private function selectOptionsIncludeLocking( $options ) {
1953                 $options = (array)$options;
1954                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1955                         if ( in_array( $lock, $options, true ) ) {
1956                                 return true;
1957                         }
1958                 }
1959
1960                 return false;
1961         }
1962
1963         /**
1964          * @param array|string $fields
1965          * @param array|string $options
1966          * @return bool
1967          */
1968         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1969                 foreach ( (array)$options as $key => $value ) {
1970                         if ( is_string( $key ) ) {
1971                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1972                                         return true;
1973                                 }
1974                         } elseif ( is_string( $value ) ) {
1975                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1976                                         return true;
1977                                 }
1978                         }
1979                 }
1980
1981                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1982                 foreach ( (array)$fields as $field ) {
1983                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1984                                 return true;
1985                         }
1986                 }
1987
1988                 return false;
1989         }
1990
1991         /**
1992          * @param array|string $conds
1993          * @param string $fname
1994          * @return array
1995          */
1996         final protected function normalizeConditions( $conds, $fname ) {
1997                 if ( $conds === null || $conds === false ) {
1998                         $this->queryLogger->warning(
1999                                 __METHOD__
2000                                 . ' called from '
2001                                 . $fname
2002                                 . ' with incorrect parameters: $conds must be a string or an array'
2003                         );
2004                         $conds = '';
2005                 }
2006
2007                 if ( !is_array( $conds ) ) {
2008                         $conds = ( $conds === '' ) ? [] : [ $conds ];
2009                 }
2010
2011                 return $conds;
2012         }
2013
2014         /**
2015          * @param array|string $var Field parameter in the style of select()
2016          * @return string|null Column name or null; ignores aliases
2017          * @throws DBUnexpectedError Errors out if multiple columns are given
2018          */
2019         final protected function extractSingleFieldFromList( $var ) {
2020                 if ( is_array( $var ) ) {
2021                         if ( !$var ) {
2022                                 $column = null;
2023                         } elseif ( count( $var ) == 1 ) {
2024                                 $column = $var[0] ?? reset( $var );
2025                         } else {
2026                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns' );
2027                         }
2028                 } else {
2029                         $column = $var;
2030                 }
2031
2032                 return $column;
2033         }
2034
2035         public function lockForUpdate(
2036                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
2037         ) {
2038                 if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
2039                         throw new DBUnexpectedError(
2040                                 $this,
2041                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
2042                         );
2043                 }
2044
2045                 $options = (array)$options;
2046                 $options[] = 'FOR UPDATE';
2047
2048                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2049         }
2050
2051         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2052                 $info = $this->fieldInfo( $table, $field );
2053
2054                 return (bool)$info;
2055         }
2056
2057         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2058                 if ( !$this->tableExists( $table ) ) {
2059                         return null;
2060                 }
2061
2062                 $info = $this->indexInfo( $table, $index, $fname );
2063                 if ( is_null( $info ) ) {
2064                         return null;
2065                 } else {
2066                         return $info !== false;
2067                 }
2068         }
2069
2070         abstract public function tableExists( $table, $fname = __METHOD__ );
2071
2072         public function indexUnique( $table, $index ) {
2073                 $indexInfo = $this->indexInfo( $table, $index );
2074
2075                 if ( !$indexInfo ) {
2076                         return null;
2077                 }
2078
2079                 return !$indexInfo[0]->Non_unique;
2080         }
2081
2082         /**
2083          * Helper for Database::insert().
2084          *
2085          * @param array $options
2086          * @return string
2087          */
2088         protected function makeInsertOptions( $options ) {
2089                 return implode( ' ', $options );
2090         }
2091
2092         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2093                 # No rows to insert, easy just return now
2094                 if ( !count( $a ) ) {
2095                         return true;
2096                 }
2097
2098                 $table = $this->tableName( $table );
2099
2100                 if ( !is_array( $options ) ) {
2101                         $options = [ $options ];
2102                 }
2103
2104                 $options = $this->makeInsertOptions( $options );
2105
2106                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2107                         $multi = true;
2108                         $keys = array_keys( $a[0] );
2109                 } else {
2110                         $multi = false;
2111                         $keys = array_keys( $a );
2112                 }
2113
2114                 $sql = 'INSERT ' . $options .
2115                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2116
2117                 if ( $multi ) {
2118                         $first = true;
2119                         foreach ( $a as $row ) {
2120                                 if ( $first ) {
2121                                         $first = false;
2122                                 } else {
2123                                         $sql .= ',';
2124                                 }
2125                                 $sql .= '(' . $this->makeList( $row ) . ')';
2126                         }
2127                 } else {
2128                         $sql .= '(' . $this->makeList( $a ) . ')';
2129                 }
2130
2131                 $this->query( $sql, $fname );
2132
2133                 return true;
2134         }
2135
2136         /**
2137          * Make UPDATE options array for Database::makeUpdateOptions
2138          *
2139          * @param array $options
2140          * @return array
2141          */
2142         protected function makeUpdateOptionsArray( $options ) {
2143                 if ( !is_array( $options ) ) {
2144                         $options = [ $options ];
2145                 }
2146
2147                 $opts = [];
2148
2149                 if ( in_array( 'IGNORE', $options ) ) {
2150                         $opts[] = 'IGNORE';
2151                 }
2152
2153                 return $opts;
2154         }
2155
2156         /**
2157          * Make UPDATE options for the Database::update function
2158          *
2159          * @param array $options The options passed to Database::update
2160          * @return string
2161          */
2162         protected function makeUpdateOptions( $options ) {
2163                 $opts = $this->makeUpdateOptionsArray( $options );
2164
2165                 return implode( ' ', $opts );
2166         }
2167
2168         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2169                 $table = $this->tableName( $table );
2170                 $opts = $this->makeUpdateOptions( $options );
2171                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2172
2173                 if ( $conds !== [] && $conds !== '*' ) {
2174                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2175                 }
2176
2177                 $this->query( $sql, $fname );
2178
2179                 return true;
2180         }
2181
2182         public function makeList( $a, $mode = self::LIST_COMMA ) {
2183                 if ( !is_array( $a ) ) {
2184                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2185                 }
2186
2187                 $first = true;
2188                 $list = '';
2189
2190                 foreach ( $a as $field => $value ) {
2191                         if ( !$first ) {
2192                                 if ( $mode == self::LIST_AND ) {
2193                                         $list .= ' AND ';
2194                                 } elseif ( $mode == self::LIST_OR ) {
2195                                         $list .= ' OR ';
2196                                 } else {
2197                                         $list .= ',';
2198                                 }
2199                         } else {
2200                                 $first = false;
2201                         }
2202
2203                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2204                                 $list .= "($value)";
2205                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2206                                 $list .= "$value";
2207                         } elseif (
2208                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2209                         ) {
2210                                 // Remove null from array to be handled separately if found
2211                                 $includeNull = false;
2212                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2213                                         $includeNull = true;
2214                                         unset( $value[$nullKey] );
2215                                 }
2216                                 if ( count( $value ) == 0 && !$includeNull ) {
2217                                         throw new InvalidArgumentException(
2218                                                 __METHOD__ . ": empty input for field $field" );
2219                                 } elseif ( count( $value ) == 0 ) {
2220                                         // only check if $field is null
2221                                         $list .= "$field IS NULL";
2222                                 } else {
2223                                         // IN clause contains at least one valid element
2224                                         if ( $includeNull ) {
2225                                                 // Group subconditions to ensure correct precedence
2226                                                 $list .= '(';
2227                                         }
2228                                         if ( count( $value ) == 1 ) {
2229                                                 // Special-case single values, as IN isn't terribly efficient
2230                                                 // Don't necessarily assume the single key is 0; we don't
2231                                                 // enforce linear numeric ordering on other arrays here.
2232                                                 $value = array_values( $value )[0];
2233                                                 $list .= $field . " = " . $this->addQuotes( $value );
2234                                         } else {
2235                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2236                                         }
2237                                         // if null present in array, append IS NULL
2238                                         if ( $includeNull ) {
2239                                                 $list .= " OR $field IS NULL)";
2240                                         }
2241                                 }
2242                         } elseif ( $value === null ) {
2243                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2244                                         $list .= "$field IS ";
2245                                 } elseif ( $mode == self::LIST_SET ) {
2246                                         $list .= "$field = ";
2247                                 }
2248                                 $list .= 'NULL';
2249                         } else {
2250                                 if (
2251                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2252                                 ) {
2253                                         $list .= "$field = ";
2254                                 }
2255                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2256                         }
2257                 }
2258
2259                 return $list;
2260         }
2261
2262         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2263                 $conds = [];
2264
2265                 foreach ( $data as $base => $sub ) {
2266                         if ( count( $sub ) ) {
2267                                 $conds[] = $this->makeList(
2268                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2269                                         self::LIST_AND );
2270                         }
2271                 }
2272
2273                 if ( $conds ) {
2274                         return $this->makeList( $conds, self::LIST_OR );
2275                 } else {
2276                         // Nothing to search for...
2277                         return false;
2278                 }
2279         }
2280
2281         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2282                 return $valuename;
2283         }
2284
2285         public function bitNot( $field ) {
2286                 return "(~$field)";
2287         }
2288
2289         public function bitAnd( $fieldLeft, $fieldRight ) {
2290                 return "($fieldLeft & $fieldRight)";
2291         }
2292
2293         public function bitOr( $fieldLeft, $fieldRight ) {
2294                 return "($fieldLeft | $fieldRight)";
2295         }
2296
2297         public function buildConcat( $stringList ) {
2298                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2299         }
2300
2301         public function buildGroupConcatField(
2302                 $delim, $table, $field, $conds = '', $join_conds = []
2303         ) {
2304                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2305
2306                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2307         }
2308
2309         public function buildSubstring( $input, $startPosition, $length = null ) {
2310                 $this->assertBuildSubstringParams( $startPosition, $length );
2311                 $functionBody = "$input FROM $startPosition";
2312                 if ( $length !== null ) {
2313                         $functionBody .= " FOR $length";
2314                 }
2315                 return 'SUBSTRING(' . $functionBody . ')';
2316         }
2317
2318         /**
2319          * Check type and bounds for parameters to self::buildSubstring()
2320          *
2321          * All supported databases have substring functions that behave the same for
2322          * positive $startPosition and non-negative $length, but behaviors differ when
2323          * given 0 or negative $startPosition or negative $length. The simplest
2324          * solution to that is to just forbid those values.
2325          *
2326          * @param int $startPosition
2327          * @param int|null $length
2328          * @since 1.31
2329          */
2330         protected function assertBuildSubstringParams( $startPosition, $length ) {
2331                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2332                         throw new InvalidArgumentException(
2333                                 '$startPosition must be a positive integer'
2334                         );
2335                 }
2336                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2337                         throw new InvalidArgumentException(
2338                                 '$length must be null or an integer greater than or equal to 0'
2339                         );
2340                 }
2341         }
2342
2343         public function buildStringCast( $field ) {
2344                 // In theory this should work for any standards-compliant
2345                 // SQL implementation, although it may not be the best way to do it.
2346                 return "CAST( $field AS CHARACTER )";
2347         }
2348
2349         public function buildIntegerCast( $field ) {
2350                 return 'CAST( ' . $field . ' AS INTEGER )';
2351         }
2352
2353         public function buildSelectSubquery(
2354                 $table, $vars, $conds = '', $fname = __METHOD__,
2355                 $options = [], $join_conds = []
2356         ) {
2357                 return new Subquery(
2358                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2359                 );
2360         }
2361
2362         public function databasesAreIndependent() {
2363                 return false;
2364         }
2365
2366         final public function selectDB( $db ) {
2367                 $this->selectDomain( new DatabaseDomain(
2368                         $db,
2369                         $this->currentDomain->getSchema(),
2370                         $this->currentDomain->getTablePrefix()
2371                 ) );
2372
2373                 return true;
2374         }
2375
2376         final public function selectDomain( $domain ) {
2377                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2378         }
2379
2380         /**
2381          * @param DatabaseDomain $domain
2382          * @throws DBConnectionError
2383          * @throws DBError
2384          * @since 1.32
2385          */
2386         protected function doSelectDomain( DatabaseDomain $domain ) {
2387                 $this->currentDomain = $domain;
2388         }
2389
2390         public function getDBname() {
2391                 return $this->currentDomain->getDatabase();
2392         }
2393
2394         public function getServer() {
2395                 return $this->server;
2396         }
2397
2398         public function tableName( $name, $format = 'quoted' ) {
2399                 if ( $name instanceof Subquery ) {
2400                         throw new DBUnexpectedError(
2401                                 $this,
2402                                 __METHOD__ . ': got Subquery instance when expecting a string'
2403                         );
2404                 }
2405
2406                 # Skip the entire process when we have a string quoted on both ends.
2407                 # Note that we check the end so that we will still quote any use of
2408                 # use of `database`.table. But won't break things if someone wants
2409                 # to query a database table with a dot in the name.
2410                 if ( $this->isQuotedIdentifier( $name ) ) {
2411                         return $name;
2412                 }
2413
2414                 # Lets test for any bits of text that should never show up in a table
2415                 # name. Basically anything like JOIN or ON which are actually part of
2416                 # SQL queries, but may end up inside of the table value to combine
2417                 # sql. Such as how the API is doing.
2418                 # Note that we use a whitespace test rather than a \b test to avoid
2419                 # any remote case where a word like on may be inside of a table name
2420                 # surrounded by symbols which may be considered word breaks.
2421                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2422                         $this->queryLogger->warning(
2423                                 __METHOD__ . ": use of subqueries is not supported this way",
2424                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2425                         );
2426
2427                         return $name;
2428                 }
2429
2430                 # Split database and table into proper variables.
2431                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2432
2433                 # Quote $table and apply the prefix if not quoted.
2434                 # $tableName might be empty if this is called from Database::replaceVars()
2435                 $tableName = "{$prefix}{$table}";
2436                 if ( $format === 'quoted'
2437                         && !$this->isQuotedIdentifier( $tableName )
2438                         && $tableName !== ''
2439                 ) {
2440                         $tableName = $this->addIdentifierQuotes( $tableName );
2441                 }
2442
2443                 # Quote $schema and $database and merge them with the table name if needed
2444                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2445                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2446
2447                 return $tableName;
2448         }
2449
2450         /**
2451          * Get the table components needed for a query given the currently selected database
2452          *
2453          * @param string $name Table name in the form of db.schema.table, db.table, or table
2454          * @return array (DB name or "" for default, schema name, table prefix, table name)
2455          */
2456         protected function qualifiedTableComponents( $name ) {
2457                 # We reverse the explode so that database.table and table both output the correct table.
2458                 $dbDetails = explode( '.', $name, 3 );
2459                 if ( count( $dbDetails ) == 3 ) {
2460                         list( $database, $schema, $table ) = $dbDetails;
2461                         # We don't want any prefix added in this case
2462                         $prefix = '';
2463                 } elseif ( count( $dbDetails ) == 2 ) {
2464                         list( $database, $table ) = $dbDetails;
2465                         # We don't want any prefix added in this case
2466                         $prefix = '';
2467                         # In dbs that support it, $database may actually be the schema
2468                         # but that doesn't affect any of the functionality here
2469                         $schema = '';
2470                 } else {
2471                         list( $table ) = $dbDetails;
2472                         if ( isset( $this->tableAliases[$table] ) ) {
2473                                 $database = $this->tableAliases[$table]['dbname'];
2474                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2475                                         ? $this->tableAliases[$table]['schema']
2476                                         : $this->relationSchemaQualifier();
2477                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2478                                         ? $this->tableAliases[$table]['prefix']
2479                                         : $this->tablePrefix();
2480                         } else {
2481                                 $database = '';
2482                                 $schema = $this->relationSchemaQualifier(); # Default schema
2483                                 $prefix = $this->tablePrefix(); # Default prefix
2484                         }
2485                 }
2486
2487                 return [ $database, $schema, $prefix, $table ];
2488         }
2489
2490         /**
2491          * @param string|null $namespace Database or schema
2492          * @param string $relation Name of table, view, sequence, etc...
2493          * @param string $format One of (raw, quoted)
2494          * @return string Relation name with quoted and merged $namespace as needed
2495          */
2496         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2497                 if ( strlen( $namespace ) ) {
2498                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2499                                 $namespace = $this->addIdentifierQuotes( $namespace );
2500                         }
2501                         $relation = $namespace . '.' . $relation;
2502                 }
2503
2504                 return $relation;
2505         }
2506
2507         public function tableNames() {
2508                 $inArray = func_get_args();
2509                 $retVal = [];
2510
2511                 foreach ( $inArray as $name ) {
2512                         $retVal[$name] = $this->tableName( $name );
2513                 }
2514
2515                 return $retVal;
2516         }
2517
2518         public function tableNamesN() {
2519                 $inArray = func_get_args();
2520                 $retVal = [];
2521
2522                 foreach ( $inArray as $name ) {
2523                         $retVal[] = $this->tableName( $name );
2524                 }
2525
2526                 return $retVal;
2527         }
2528
2529         /**
2530          * Get an aliased table name
2531          *
2532          * This returns strings like "tableName AS newTableName" for aliased tables
2533          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2534          *
2535          * @see Database::tableName()
2536          * @param string|Subquery $table Table name or object with a 'sql' field
2537          * @param string|bool $alias Table alias (optional)
2538          * @return string SQL name for aliased table. Will not alias a table to its own name
2539          */
2540         protected function tableNameWithAlias( $table, $alias = false ) {
2541                 if ( is_string( $table ) ) {
2542                         $quotedTable = $this->tableName( $table );
2543                 } elseif ( $table instanceof Subquery ) {
2544                         $quotedTable = (string)$table;
2545                 } else {
2546                         throw new InvalidArgumentException( "Table must be a string or Subquery" );
2547                 }
2548
2549                 if ( $alias === false || $alias === $table ) {
2550                         if ( $table instanceof Subquery ) {
2551                                 throw new InvalidArgumentException( "Subquery table missing alias" );
2552                         }
2553
2554                         return $quotedTable;
2555                 } else {
2556                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2557                 }
2558         }
2559
2560         /**
2561          * Gets an array of aliased table names
2562          *
2563          * @param array $tables [ [alias] => table ]
2564          * @return string[] See tableNameWithAlias()
2565          */
2566         protected function tableNamesWithAlias( $tables ) {
2567                 $retval = [];
2568                 foreach ( $tables as $alias => $table ) {
2569                         if ( is_numeric( $alias ) ) {
2570                                 $alias = $table;
2571                         }
2572                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2573                 }
2574
2575                 return $retval;
2576         }
2577
2578         /**
2579          * Get an aliased field name
2580          * e.g. fieldName AS newFieldName
2581          *
2582          * @param string $name Field name
2583          * @param string|bool $alias Alias (optional)
2584          * @return string SQL name for aliased field. Will not alias a field to its own name
2585          */
2586         protected function fieldNameWithAlias( $name, $alias = false ) {
2587                 if ( !$alias || (string)$alias === (string)$name ) {
2588                         return $name;
2589                 } else {
2590                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2591                 }
2592         }
2593
2594         /**
2595          * Gets an array of aliased field names
2596          *
2597          * @param array $fields [ [alias] => field ]
2598          * @return string[] See fieldNameWithAlias()
2599          */
2600         protected function fieldNamesWithAlias( $fields ) {
2601                 $retval = [];
2602                 foreach ( $fields as $alias => $field ) {
2603                         if ( is_numeric( $alias ) ) {
2604                                 $alias = $field;
2605                         }
2606                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2607                 }
2608
2609                 return $retval;
2610         }
2611
2612         /**
2613          * Get the aliased table name clause for a FROM clause
2614          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2615          *
2616          * @param array $tables ( [alias] => table )
2617          * @param array $use_index Same as for select()
2618          * @param array $ignore_index Same as for select()
2619          * @param array $join_conds Same as for select()
2620          * @return string
2621          */
2622         protected function tableNamesWithIndexClauseOrJOIN(
2623                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2624         ) {
2625                 $ret = [];
2626                 $retJOIN = [];
2627                 $use_index = (array)$use_index;
2628                 $ignore_index = (array)$ignore_index;
2629                 $join_conds = (array)$join_conds;
2630
2631                 foreach ( $tables as $alias => $table ) {
2632                         if ( !is_string( $alias ) ) {
2633                                 // No alias? Set it equal to the table name
2634                                 $alias = $table;
2635                         }
2636
2637                         if ( is_array( $table ) ) {
2638                                 // A parenthesized group
2639                                 if ( count( $table ) > 1 ) {
2640                                         $joinedTable = '(' .
2641                                                 $this->tableNamesWithIndexClauseOrJOIN(
2642                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2643                                 } else {
2644                                         // Degenerate case
2645                                         $innerTable = reset( $table );
2646                                         $innerAlias = key( $table );
2647                                         $joinedTable = $this->tableNameWithAlias(
2648                                                 $innerTable,
2649                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2650                                         );
2651                                 }
2652                         } else {
2653                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2654                         }
2655
2656                         // Is there a JOIN clause for this table?
2657                         if ( isset( $join_conds[$alias] ) ) {
2658                                 list( $joinType, $conds ) = $join_conds[$alias];
2659                                 $tableClause = $joinType;
2660                                 $tableClause .= ' ' . $joinedTable;
2661                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2662                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2663                                         if ( $use != '' ) {
2664                                                 $tableClause .= ' ' . $use;
2665                                         }
2666                                 }
2667                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2668                                         $ignore = $this->ignoreIndexClause(
2669                                                 implode( ',', (array)$ignore_index[$alias] ) );
2670                                         if ( $ignore != '' ) {
2671                                                 $tableClause .= ' ' . $ignore;
2672                                         }
2673                                 }
2674                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2675                                 if ( $on != '' ) {
2676                                         $tableClause .= ' ON (' . $on . ')';
2677                                 }
2678
2679                                 $retJOIN[] = $tableClause;
2680                         } elseif ( isset( $use_index[$alias] ) ) {
2681                                 // Is there an INDEX clause for this table?
2682                                 $tableClause = $joinedTable;
2683                                 $tableClause .= ' ' . $this->useIndexClause(
2684                                                 implode( ',', (array)$use_index[$alias] )
2685                                         );
2686
2687                                 $ret[] = $tableClause;
2688                         } elseif ( isset( $ignore_index[$alias] ) ) {
2689                                 // Is there an INDEX clause for this table?
2690                                 $tableClause = $joinedTable;
2691                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2692                                                 implode( ',', (array)$ignore_index[$alias] )
2693                                         );
2694
2695                                 $ret[] = $tableClause;
2696                         } else {
2697                                 $tableClause = $joinedTable;
2698
2699                                 $ret[] = $tableClause;
2700                         }
2701                 }
2702
2703                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2704                 $implicitJoins = implode( ',', $ret );
2705                 $explicitJoins = implode( ' ', $retJOIN );
2706
2707                 // Compile our final table clause
2708                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2709         }
2710
2711         /**
2712          * Allows for index remapping in queries where this is not consistent across DBMS
2713          *
2714          * @param string $index
2715          * @return string
2716          */
2717         protected function indexName( $index ) {
2718                 return $this->indexAliases[$index] ?? $index;
2719         }
2720
2721         public function addQuotes( $s ) {
2722                 if ( $s instanceof Blob ) {
2723                         $s = $s->fetch();
2724                 }
2725                 if ( $s === null ) {
2726                         return 'NULL';
2727                 } elseif ( is_bool( $s ) ) {
2728                         return (int)$s;
2729                 } else {
2730                         # This will also quote numeric values. This should be harmless,
2731                         # and protects against weird problems that occur when they really
2732                         # _are_ strings such as article titles and string->number->string
2733                         # conversion is not 1:1.
2734                         return "'" . $this->strencode( $s ) . "'";
2735                 }
2736         }
2737
2738         public function addIdentifierQuotes( $s ) {
2739                 return '"' . str_replace( '"', '""', $s ) . '"';
2740         }
2741
2742         /**
2743          * Returns if the given identifier looks quoted or not according to
2744          * the database convention for quoting identifiers .
2745          *
2746          * @note Do not use this to determine if untrusted input is safe.
2747          *   A malicious user can trick this function.
2748          * @param string $name
2749          * @return bool
2750          */
2751         public function isQuotedIdentifier( $name ) {
2752                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2753         }
2754
2755         /**
2756          * @param string $s
2757          * @param string $escapeChar
2758          * @return string
2759          */
2760         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2761                 return str_replace( [ $escapeChar, '%', '_' ],
2762                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2763                         $s );
2764         }
2765
2766         public function buildLike( $param, ...$params ) {
2767                 if ( is_array( $param ) ) {
2768                         $params = $param;
2769                 } else {
2770                         $params = func_get_args();
2771                 }
2772
2773                 $s = '';
2774
2775                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2776                 // may escape backslashes, creating problems of double escaping. The `
2777                 // character has good cross-DBMS compatibility, avoiding special operators
2778                 // in MS SQL like ^ and %
2779                 $escapeChar = '`';
2780
2781                 foreach ( $params as $value ) {
2782                         if ( $value instanceof LikeMatch ) {
2783                                 $s .= $value->toString();
2784                         } else {
2785                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2786                         }
2787                 }
2788
2789                 return ' LIKE ' .
2790                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2791         }
2792
2793         public function anyChar() {
2794                 return new LikeMatch( '_' );
2795         }
2796
2797         public function anyString() {
2798                 return new LikeMatch( '%' );
2799         }
2800
2801         public function nextSequenceValue( $seqName ) {
2802                 return null;
2803         }
2804
2805         /**
2806          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2807          * is only needed because a) MySQL must be as efficient as possible due to
2808          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2809          * which index to pick. Anyway, other databases might have different
2810          * indexes on a given table. So don't bother overriding this unless you're
2811          * MySQL.
2812          * @param string $index
2813          * @return string
2814          */
2815         public function useIndexClause( $index ) {
2816                 return '';
2817         }
2818
2819         /**
2820          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2821          * is only needed because a) MySQL must be as efficient as possible due to
2822          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2823          * which index to pick. Anyway, other databases might have different
2824          * indexes on a given table. So don't bother overriding this unless you're
2825          * MySQL.
2826          * @param string $index
2827          * @return string
2828          */
2829         public function ignoreIndexClause( $index ) {
2830                 return '';
2831         }
2832
2833         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2834                 if ( count( $rows ) == 0 ) {
2835                         return;
2836                 }
2837
2838                 $uniqueIndexes = (array)$uniqueIndexes;
2839                 // Single row case
2840                 if ( !is_array( reset( $rows ) ) ) {
2841                         $rows = [ $rows ];
2842                 }
2843
2844                 try {
2845                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2846                         $affectedRowCount = 0;
2847                         foreach ( $rows as $row ) {
2848                                 // Delete rows which collide with this one
2849                                 $indexWhereClauses = [];
2850                                 foreach ( $uniqueIndexes as $index ) {
2851                                         $indexColumns = (array)$index;
2852                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2853                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2854                                                 throw new DBUnexpectedError(
2855                                                         $this,
2856                                                         'New record does not provide all values for unique key (' .
2857                                                         implode( ', ', $indexColumns ) . ')'
2858                                                 );
2859                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2860                                                 throw new DBUnexpectedError(
2861                                                         $this,
2862                                                         'New record has a null value for unique key (' .
2863                                                         implode( ', ', $indexColumns ) . ')'
2864                                                 );
2865                                         }
2866                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2867                                 }
2868
2869                                 if ( $indexWhereClauses ) {
2870                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2871                                         $affectedRowCount += $this->affectedRows();
2872                                 }
2873
2874                                 // Now insert the row
2875                                 $this->insert( $table, $row, $fname );
2876                                 $affectedRowCount += $this->affectedRows();
2877                         }
2878                         $this->endAtomic( $fname );
2879                         $this->affectedRowCount = $affectedRowCount;
2880                 } catch ( Exception $e ) {
2881                         $this->cancelAtomic( $fname );
2882                         throw $e;
2883                 }
2884         }
2885
2886         /**
2887          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2888          * statement.
2889          *
2890          * @param string $table Table name
2891          * @param array|string $rows Row(s) to insert
2892          * @param string $fname Caller function name
2893          */
2894         protected function nativeReplace( $table, $rows, $fname ) {
2895                 $table = $this->tableName( $table );
2896
2897                 # Single row case
2898                 if ( !is_array( reset( $rows ) ) ) {
2899                         $rows = [ $rows ];
2900                 }
2901
2902                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2903                 $first = true;
2904
2905                 foreach ( $rows as $row ) {
2906                         if ( $first ) {
2907                                 $first = false;
2908                         } else {
2909                                 $sql .= ',';
2910                         }
2911
2912                         $sql .= '(' . $this->makeList( $row ) . ')';
2913                 }
2914
2915                 $this->query( $sql, $fname );
2916         }
2917
2918         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2919                 $fname = __METHOD__
2920         ) {
2921                 if ( $rows === [] ) {
2922                         return true; // nothing to do
2923                 }
2924
2925                 $uniqueIndexes = (array)$uniqueIndexes;
2926                 if ( !is_array( reset( $rows ) ) ) {
2927                         $rows = [ $rows ];
2928                 }
2929
2930                 if ( count( $uniqueIndexes ) ) {
2931                         $clauses = []; // list WHERE clauses that each identify a single row
2932                         foreach ( $rows as $row ) {
2933                                 foreach ( $uniqueIndexes as $index ) {
2934                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2935                                         $rowKey = []; // unique key to this row
2936                                         foreach ( $index as $column ) {
2937                                                 $rowKey[$column] = $row[$column];
2938                                         }
2939                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2940                                 }
2941                         }
2942                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2943                 } else {
2944                         $where = false;
2945                 }
2946
2947                 $affectedRowCount = 0;
2948                 try {
2949                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2950                         # Update any existing conflicting row(s)
2951                         if ( $where !== false ) {
2952                                 $this->update( $table, $set, $where, $fname );
2953                                 $affectedRowCount += $this->affectedRows();
2954                         }
2955                         # Now insert any non-conflicting row(s)
2956                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2957                         $affectedRowCount += $this->affectedRows();
2958                         $this->endAtomic( $fname );
2959                         $this->affectedRowCount = $affectedRowCount;
2960                 } catch ( Exception $e ) {
2961                         $this->cancelAtomic( $fname );
2962                         throw $e;
2963                 }
2964
2965                 return true;
2966         }
2967
2968         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2969                 $fname = __METHOD__
2970         ) {
2971                 if ( !$conds ) {
2972                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2973                 }
2974
2975                 $delTable = $this->tableName( $delTable );
2976                 $joinTable = $this->tableName( $joinTable );
2977                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2978                 if ( $conds != '*' ) {
2979                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2980                 }
2981                 $sql .= ')';
2982
2983                 $this->query( $sql, $fname );
2984         }
2985
2986         public function textFieldSize( $table, $field ) {
2987                 $table = $this->tableName( $table );
2988                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2989                 $res = $this->query( $sql, __METHOD__ );
2990                 $row = $this->fetchObject( $res );
2991
2992                 $m = [];
2993
2994                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2995                         $size = $m[1];
2996                 } else {
2997                         $size = -1;
2998                 }
2999
3000                 return $size;
3001         }
3002
3003         public function delete( $table, $conds, $fname = __METHOD__ ) {
3004                 if ( !$conds ) {
3005                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
3006                 }
3007
3008                 $table = $this->tableName( $table );
3009                 $sql = "DELETE FROM $table";
3010
3011                 if ( $conds != '*' ) {
3012                         if ( is_array( $conds ) ) {
3013                                 $conds = $this->makeList( $conds, self::LIST_AND );
3014                         }
3015                         $sql .= ' WHERE ' . $conds;
3016                 }
3017
3018                 $this->query( $sql, $fname );
3019
3020                 return true;
3021         }
3022
3023         final public function insertSelect(
3024                 $destTable, $srcTable, $varMap, $conds,
3025                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3026         ) {
3027                 static $hints = [ 'NO_AUTO_COLUMNS' ];
3028
3029                 $insertOptions = (array)$insertOptions;
3030                 $selectOptions = (array)$selectOptions;
3031
3032                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
3033                         // For massive migrations with downtime, we don't want to select everything
3034                         // into memory and OOM, so do all this native on the server side if possible.
3035                         $this->nativeInsertSelect(
3036                                 $destTable,
3037                                 $srcTable,
3038                                 $varMap,
3039                                 $conds,
3040                                 $fname,
3041                                 array_diff( $insertOptions, $hints ),
3042                                 $selectOptions,
3043                                 $selectJoinConds
3044                         );
3045                 } else {
3046                         $this->nonNativeInsertSelect(
3047                                 $destTable,
3048                                 $srcTable,
3049                                 $varMap,
3050                                 $conds,
3051                                 $fname,
3052                                 array_diff( $insertOptions, $hints ),
3053                                 $selectOptions,
3054                                 $selectJoinConds
3055                         );
3056                 }
3057
3058                 return true;
3059         }
3060
3061         /**
3062          * @param array $insertOptions INSERT options
3063          * @param array $selectOptions SELECT options
3064          * @return bool Whether an INSERT SELECT with these options will be replication safe
3065          * @since 1.31
3066          */
3067         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3068                 return true;
3069         }
3070
3071         /**
3072          * Implementation of insertSelect() based on select() and insert()
3073          *
3074          * @see IDatabase::insertSelect()
3075          * @since 1.30
3076          * @param string $destTable
3077          * @param string|array $srcTable
3078          * @param array $varMap
3079          * @param array $conds
3080          * @param string $fname
3081          * @param array $insertOptions
3082          * @param array $selectOptions
3083          * @param array $selectJoinConds
3084          */
3085         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3086                 $fname = __METHOD__,
3087                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3088         ) {
3089                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3090                 // on only the master (without needing row-based-replication). It also makes it easy to
3091                 // know how big the INSERT is going to be.
3092                 $fields = [];
3093                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3094                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3095                 }
3096                 $selectOptions[] = 'FOR UPDATE';
3097                 $res = $this->select(
3098                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3099                 );
3100                 if ( !$res ) {
3101                         return;
3102                 }
3103
3104                 try {
3105                         $affectedRowCount = 0;
3106                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3107                         $rows = [];
3108                         $ok = true;
3109                         foreach ( $res as $row ) {
3110                                 $rows[] = (array)$row;
3111
3112                                 // Avoid inserts that are too huge
3113                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3114                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3115                                         if ( !$ok ) {
3116                                                 break;
3117                                         }
3118                                         $affectedRowCount += $this->affectedRows();
3119                                         $rows = [];
3120                                 }
3121                         }
3122                         if ( $rows && $ok ) {
3123                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3124                                 if ( $ok ) {
3125                                         $affectedRowCount += $this->affectedRows();
3126                                 }
3127                         }
3128                         if ( $ok ) {
3129                                 $this->endAtomic( $fname );
3130                                 $this->affectedRowCount = $affectedRowCount;
3131                         } else {
3132                                 $this->cancelAtomic( $fname );
3133                         }
3134                 } catch ( Exception $e ) {
3135                         $this->cancelAtomic( $fname );
3136                         throw $e;
3137                 }
3138         }
3139
3140         /**
3141          * Native server-side implementation of insertSelect() for situations where
3142          * we don't want to select everything into memory
3143          *
3144          * @see IDatabase::insertSelect()
3145          * @param string $destTable
3146          * @param string|array $srcTable
3147          * @param array $varMap
3148          * @param array $conds
3149          * @param string $fname
3150          * @param array $insertOptions
3151          * @param array $selectOptions
3152          * @param array $selectJoinConds
3153          */
3154         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3155                 $fname = __METHOD__,
3156                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3157         ) {
3158                 $destTable = $this->tableName( $destTable );
3159
3160                 if ( !is_array( $insertOptions ) ) {
3161                         $insertOptions = [ $insertOptions ];
3162                 }
3163
3164                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3165
3166                 $selectSql = $this->selectSQLText(
3167                         $srcTable,
3168                         array_values( $varMap ),
3169                         $conds,
3170                         $fname,
3171                         $selectOptions,
3172                         $selectJoinConds
3173                 );
3174
3175                 $sql = "INSERT $insertOptions" .
3176                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3177                         $selectSql;
3178
3179                 $this->query( $sql, $fname );
3180         }
3181
3182         public function limitResult( $sql, $limit, $offset = false ) {
3183                 if ( !is_numeric( $limit ) ) {
3184                         throw new DBUnexpectedError(
3185                                 $this,
3186                                 "Invalid non-numeric limit passed to " . __METHOD__
3187                         );
3188                 }
3189                 // This version works in MySQL and SQLite. It will very likely need to be
3190                 // overridden for most other RDBMS subclasses.
3191                 return "$sql LIMIT "
3192                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3193                         . "{$limit} ";
3194         }
3195
3196         public function unionSupportsOrderAndLimit() {
3197                 return true; // True for almost every DB supported
3198         }
3199
3200         public function unionQueries( $sqls, $all ) {
3201                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3202
3203                 return '(' . implode( $glue, $sqls ) . ')';
3204         }
3205
3206         public function unionConditionPermutations(
3207                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3208                 $options = [], $join_conds = []
3209         ) {
3210                 // First, build the Cartesian product of $permute_conds
3211                 $conds = [ [] ];
3212                 foreach ( $permute_conds as $field => $values ) {
3213                         if ( !$values ) {
3214                                 // Skip empty $values
3215                                 continue;
3216                         }
3217                         $values = array_unique( $values ); // For sanity
3218                         $newConds = [];
3219                         foreach ( $conds as $cond ) {
3220                                 foreach ( $values as $value ) {
3221                                         $cond[$field] = $value;
3222                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3223                                 }
3224                         }
3225                         $conds = $newConds;
3226                 }
3227
3228                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3229
3230                 // If there's just one condition and no subordering, hand off to
3231                 // selectSQLText directly.
3232                 if ( count( $conds ) === 1 &&
3233                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3234                 ) {
3235                         return $this->selectSQLText(
3236                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3237                         );
3238                 }
3239
3240                 // Otherwise, we need to pull out the order and limit to apply after
3241                 // the union. Then build the SQL queries for each set of conditions in
3242                 // $conds. Then union them together (using UNION ALL, because the
3243                 // product *should* already be distinct).
3244                 $orderBy = $this->makeOrderBy( $options );
3245                 $limit = $options['LIMIT'] ?? null;
3246                 $offset = $options['OFFSET'] ?? false;
3247                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3248                 if ( !$this->unionSupportsOrderAndLimit() ) {
3249                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3250                 } else {
3251                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3252                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3253                         }
3254                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3255                                 // We need to increase the limit by the offset rather than
3256                                 // using the offset directly, otherwise it'll skip incorrectly
3257                                 // in the subqueries.
3258                                 $options['LIMIT'] = $limit + $offset;
3259                                 unset( $options['OFFSET'] );
3260                         }
3261                 }
3262
3263                 $sqls = [];
3264                 foreach ( $conds as $cond ) {
3265                         $sqls[] = $this->selectSQLText(
3266                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3267                         );
3268                 }
3269                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3270                 if ( $limit !== null ) {
3271                         $sql = $this->limitResult( $sql, $limit, $offset );
3272                 }
3273
3274                 return $sql;
3275         }
3276
3277         public function conditional( $cond, $trueVal, $falseVal ) {
3278                 if ( is_array( $cond ) ) {
3279                         $cond = $this->makeList( $cond, self::LIST_AND );
3280                 }
3281
3282                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3283         }
3284
3285         public function strreplace( $orig, $old, $new ) {
3286                 return "REPLACE({$orig}, {$old}, {$new})";
3287         }
3288
3289         public function getServerUptime() {
3290                 return 0;
3291         }
3292
3293         public function wasDeadlock() {
3294                 return false;
3295         }
3296
3297         public function wasLockTimeout() {
3298                 return false;
3299         }
3300
3301         public function wasConnectionLoss() {
3302                 return $this->wasConnectionError( $this->lastErrno() );
3303         }
3304
3305         public function wasReadOnlyError() {
3306                 return false;
3307         }
3308
3309         public function wasErrorReissuable() {
3310                 return (
3311                         $this->wasDeadlock() ||
3312                         $this->wasLockTimeout() ||
3313                         $this->wasConnectionLoss()
3314                 );
3315         }
3316
3317         /**
3318          * Do not use this method outside of Database/DBError classes
3319          *
3320          * @param int|string $errno
3321          * @return bool Whether the given query error was a connection drop
3322          */
3323         public function wasConnectionError( $errno ) {
3324                 return false;
3325         }
3326
3327         /**
3328          * @return bool Whether it is known that the last query error only caused statement rollback
3329          * @note This is for backwards compatibility for callers catching DBError exceptions in
3330          *   order to ignore problems like duplicate key errors or foriegn key violations
3331          * @since 1.31
3332          */
3333         protected function wasKnownStatementRollbackError() {
3334                 return false; // don't know; it could have caused a transaction rollback
3335         }
3336
3337         public function deadlockLoop() {
3338                 $args = func_get_args();
3339                 $function = array_shift( $args );
3340                 $tries = self::$DEADLOCK_TRIES;
3341
3342                 $this->begin( __METHOD__ );
3343
3344                 $retVal = null;
3345                 /** @var Exception $e */
3346                 $e = null;
3347                 do {
3348                         try {
3349                                 $retVal = $function( ...$args );
3350                                 break;
3351                         } catch ( DBQueryError $e ) {
3352                                 if ( $this->wasDeadlock() ) {
3353                                         // Retry after a randomized delay
3354                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3355                                 } else {
3356                                         // Throw the error back up
3357                                         throw $e;
3358                                 }
3359                         }
3360                 } while ( --$tries > 0 );
3361
3362                 if ( $tries <= 0 ) {
3363                         // Too many deadlocks; give up
3364                         $this->rollback( __METHOD__ );
3365                         throw $e;
3366                 } else {
3367                         $this->commit( __METHOD__ );
3368
3369                         return $retVal;
3370                 }
3371         }
3372
3373         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3374                 # Real waits are implemented in the subclass.
3375                 return 0;
3376         }
3377
3378         public function getReplicaPos() {
3379                 # Stub
3380                 return false;
3381         }
3382
3383         public function getMasterPos() {
3384                 # Stub
3385                 return false;
3386         }
3387
3388         public function serverIsReadOnly() {
3389                 return false;
3390         }
3391
3392         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3393                 if ( !$this->trxLevel() ) {
3394                         throw new DBUnexpectedError( $this, "No transaction is active" );
3395                 }
3396                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3397         }
3398
3399         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3400                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3401                         // Start an implicit transaction similar to how query() does
3402                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3403                         $this->trxAutomatic = true;
3404                 }
3405
3406                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3407                 if ( !$this->trxLevel() ) {
3408                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3409                 }
3410         }
3411
3412         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3413                 $this->onTransactionCommitOrIdle( $callback, $fname );
3414         }
3415
3416         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3417                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3418                         // Start an implicit transaction similar to how query() does
3419                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3420                         $this->trxAutomatic = true;
3421                 }
3422
3423                 if ( $this->trxLevel() ) {
3424                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3425                 } else {
3426                         // No transaction is active nor will start implicitly, so make one for this callback
3427                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3428                         try {
3429                                 $callback( $this );
3430                                 $this->endAtomic( __METHOD__ );
3431                         } catch ( Exception $e ) {
3432                                 $this->cancelAtomic( __METHOD__ );
3433                                 throw $e;
3434                         }
3435                 }
3436         }
3437
3438         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3439                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3440                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3441                 }
3442                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3443         }
3444
3445         /**
3446          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3447          */
3448         private function currentAtomicSectionId() {
3449                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3450                         $levelInfo = end( $this->trxAtomicLevels );
3451
3452                         return $levelInfo[1];
3453                 }
3454
3455                 return null;
3456         }
3457
3458         /**
3459          * Hoist callback ownership for callbacks in a section to a parent section.
3460          * All callbacks should have an owner that is present in trxAtomicLevels.
3461          * @param AtomicSectionIdentifier $old
3462          * @param AtomicSectionIdentifier $new
3463          */
3464         private function reassignCallbacksForSection(
3465                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3466         ) {
3467                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3468                         if ( $info[2] === $old ) {
3469                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3470                         }
3471                 }
3472                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3473                         if ( $info[2] === $old ) {
3474                                 $this->trxIdleCallbacks[$key][2] = $new;
3475                         }
3476                 }
3477                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3478                         if ( $info[2] === $old ) {
3479                                 $this->trxEndCallbacks[$key][2] = $new;
3480                         }
3481                 }
3482                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3483                         if ( $info[2] === $old ) {
3484                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3485                         }
3486                 }
3487         }
3488
3489         /**
3490          * Update callbacks that were owned by cancelled atomic sections.
3491          *
3492          * Callbacks for "on commit" should never be run if they're owned by a
3493          * section that won't be committed.
3494          *
3495          * Callbacks for "on resolution" need to reflect that the section was
3496          * rolled back, even if the transaction as a whole commits successfully.
3497          *
3498          * Callbacks for "on section cancel" should already have been consumed,
3499          * but errors during the cancellation itself can prevent that while still
3500          * destroying the section. Hoist any such callbacks to the new top section,
3501          * which we assume will itself have to be cancelled or rolled back to
3502          * resolve the error.
3503          *
3504          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3505          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3506          * @throws UnexpectedValueException
3507          */
3508         private function modifyCallbacksForCancel(
3509                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3510         ) {
3511                 // Cancel the "on commit" callbacks owned by this savepoint
3512                 $this->trxIdleCallbacks = array_filter(
3513                         $this->trxIdleCallbacks,
3514                         function ( $entry ) use ( $sectionIds ) {
3515                                 return !in_array( $entry[2], $sectionIds, true );
3516                         }
3517                 );
3518                 $this->trxPreCommitCallbacks = array_filter(
3519                         $this->trxPreCommitCallbacks,
3520                         function ( $entry ) use ( $sectionIds ) {
3521                                 return !in_array( $entry[2], $sectionIds, true );
3522                         }
3523                 );
3524                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3525                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3526                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3527                                 $callback = $entry[0];
3528                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3529                                         // @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
3530                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3531                                 };
3532                                 // This "on resolution" callback no longer belongs to a section.
3533                                 $this->trxEndCallbacks[$key][2] = null;
3534                         }
3535                 }
3536                 // Hoist callback ownership for section cancel callbacks to the new top section
3537                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3538                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3539                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3540                         }
3541                 }
3542         }
3543
3544         final public function setTransactionListener( $name, callable $callback = null ) {
3545                 if ( $callback ) {
3546                         $this->trxRecurringCallbacks[$name] = $callback;
3547                 } else {
3548                         unset( $this->trxRecurringCallbacks[$name] );
3549                 }
3550         }
3551
3552         /**
3553          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3554          *
3555          * This method should not be used outside of Database/LoadBalancer
3556          *
3557          * @param bool $suppress
3558          * @since 1.28
3559          */
3560         final public function setTrxEndCallbackSuppression( $suppress ) {
3561                 $this->trxEndCallbacksSuppressed = $suppress;
3562         }
3563
3564         /**
3565          * Actually consume and run any "on transaction idle/resolution" callbacks.
3566          *
3567          * This method should not be used outside of Database/LoadBalancer
3568          *
3569          * @param int $trigger IDatabase::TRIGGER_* constant
3570          * @return int Number of callbacks attempted
3571          * @since 1.20
3572          * @throws Exception
3573          */
3574         public function runOnTransactionIdleCallbacks( $trigger ) {
3575                 if ( $this->trxLevel() ) { // sanity
3576                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open' );
3577                 }
3578
3579                 if ( $this->trxEndCallbacksSuppressed ) {
3580                         return 0;
3581                 }
3582
3583                 $count = 0;
3584                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3585                 /** @var Exception $e */
3586                 $e = null; // first exception
3587                 do { // callbacks may add callbacks :)
3588                         $callbacks = array_merge(
3589                                 $this->trxIdleCallbacks,
3590                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3591                         );
3592                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3593                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3594
3595                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3596                         // But always consume them.
3597                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3598                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3599                         }
3600                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3601
3602                         foreach ( $callbacks as $callback ) {
3603                                 ++$count;
3604                                 list( $phpCallback ) = $callback;
3605                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3606                                 try {
3607                                         // @phan-suppress-next-line PhanParamTooManyCallable
3608                                         call_user_func( $phpCallback, $trigger, $this );
3609                                 } catch ( Exception $ex ) {
3610                                         call_user_func( $this->errorLogger, $ex );
3611                                         $e = $e ?: $ex;
3612                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3613                                         // their transactions are ended so other callbacks don't fail
3614                                         if ( $this->trxLevel() ) {
3615                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3616                                         }
3617                                 } finally {
3618                                         if ( $autoTrx ) {
3619                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3620                                         } else {
3621                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3622                                         }
3623                                 }
3624                         }
3625                 } while ( count( $this->trxIdleCallbacks ) );
3626
3627                 if ( $e instanceof Exception ) {
3628                         throw $e; // re-throw any first exception
3629                 }
3630
3631                 return $count;
3632         }
3633
3634         /**
3635          * Actually consume and run any "on transaction pre-commit" callbacks.
3636          *
3637          * This method should not be used outside of Database/LoadBalancer
3638          *
3639          * @since 1.22
3640          * @return int Number of callbacks attempted
3641          * @throws Exception
3642          */
3643         public function runOnTransactionPreCommitCallbacks() {
3644                 $count = 0;
3645
3646                 $e = null; // first exception
3647                 do { // callbacks may add callbacks :)
3648                         $callbacks = $this->trxPreCommitCallbacks;
3649                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3650                         foreach ( $callbacks as $callback ) {
3651                                 try {
3652                                         ++$count;
3653                                         list( $phpCallback ) = $callback;
3654                                         $phpCallback( $this );
3655                                 } catch ( Exception $ex ) {
3656                                         ( $this->errorLogger )( $ex );
3657                                         $e = $e ?: $ex;
3658                                 }
3659                         }
3660                 } while ( count( $this->trxPreCommitCallbacks ) );
3661
3662                 if ( $e instanceof Exception ) {
3663                         throw $e; // re-throw any first exception
3664                 }
3665
3666                 return $count;
3667         }
3668
3669         /**
3670          * Actually run any "atomic section cancel" callbacks.
3671          *
3672          * @param int $trigger IDatabase::TRIGGER_* constant
3673          * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
3674          *  null on transaction rollback
3675          */
3676         private function runOnAtomicSectionCancelCallbacks(
3677                 $trigger, array $sectionIds = null
3678         ) {
3679                 /** @var Exception|Throwable $e */
3680                 $e = null; // first exception
3681
3682                 $notCancelled = [];
3683                 do {
3684                         $callbacks = $this->trxSectionCancelCallbacks;
3685                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3686                         foreach ( $callbacks as $entry ) {
3687                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3688                                         try {
3689                                                 $entry[0]( $trigger, $this );
3690                                         } catch ( Exception $ex ) {
3691                                                 ( $this->errorLogger )( $ex );
3692                                                 $e = $e ?: $ex;
3693                                         } catch ( Throwable $ex ) {
3694                                                 // @todo: Log?
3695                                                 $e = $e ?: $ex;
3696                                         }
3697                                 } else {
3698                                         $notCancelled[] = $entry;
3699                                 }
3700                         }
3701                 } while ( count( $this->trxSectionCancelCallbacks ) );
3702                 $this->trxSectionCancelCallbacks = $notCancelled;
3703
3704                 if ( $e !== null ) {
3705                         throw $e; // re-throw any first Exception/Throwable
3706                 }
3707         }
3708
3709         /**
3710          * Actually run any "transaction listener" callbacks.
3711          *
3712          * This method should not be used outside of Database/LoadBalancer
3713          *
3714          * @param int $trigger IDatabase::TRIGGER_* constant
3715          * @throws Exception
3716          * @since 1.20
3717          */
3718         public function runTransactionListenerCallbacks( $trigger ) {
3719                 if ( $this->trxEndCallbacksSuppressed ) {
3720                         return;
3721                 }
3722
3723                 /** @var Exception $e */
3724                 $e = null; // first exception
3725
3726                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3727                         try {
3728                                 $phpCallback( $trigger, $this );
3729                         } catch ( Exception $ex ) {
3730                                 ( $this->errorLogger )( $ex );
3731                                 $e = $e ?: $ex;
3732                         }
3733                 }
3734
3735                 if ( $e instanceof Exception ) {
3736                         throw $e; // re-throw any first exception
3737                 }
3738         }
3739
3740         /**
3741          * Create a savepoint
3742          *
3743          * This is used internally to implement atomic sections. It should not be
3744          * used otherwise.
3745          *
3746          * @since 1.31
3747          * @param string $identifier Identifier for the savepoint
3748          * @param string $fname Calling function name
3749          */
3750         protected function doSavepoint( $identifier, $fname ) {
3751                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3752         }
3753
3754         /**
3755          * Release a savepoint
3756          *
3757          * This is used internally to implement atomic sections. It should not be
3758          * used otherwise.
3759          *
3760          * @since 1.31
3761          * @param string $identifier Identifier for the savepoint
3762          * @param string $fname Calling function name
3763          */
3764         protected function doReleaseSavepoint( $identifier, $fname ) {
3765                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3766         }
3767
3768         /**
3769          * Rollback to a savepoint
3770          *
3771          * This is used internally to implement atomic sections. It should not be
3772          * used otherwise.
3773          *
3774          * @since 1.31
3775          * @param string $identifier Identifier for the savepoint
3776          * @param string $fname Calling function name
3777          */
3778         protected function doRollbackToSavepoint( $identifier, $fname ) {
3779                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3780         }
3781
3782         /**
3783          * @param string $fname
3784          * @return string
3785          */
3786         private function nextSavepointId( $fname ) {
3787                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3788                 if ( strlen( $savepointId ) > 30 ) {
3789                         // 30 == Oracle's identifier length limit (pre 12c)
3790                         // With a 22 character prefix, that puts the highest number at 99999999.
3791                         throw new DBUnexpectedError(
3792                                 $this,
3793                                 'There have been an excessively large number of atomic sections in a transaction'
3794                                 . " started by $this->trxFname (at $fname)"
3795                         );
3796                 }
3797
3798                 return $savepointId;
3799         }
3800
3801         final public function startAtomic(
3802                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3803         ) {
3804                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3805
3806                 if ( !$this->trxLevel() ) {
3807                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3808                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3809                         // in all changes being in one transaction to keep requests transactional.
3810                         if ( $this->getFlag( self::DBO_TRX ) ) {
3811                                 // Since writes could happen in between the topmost atomic sections as part
3812                                 // of the transaction, those sections will need savepoints.
3813                                 $savepointId = $this->nextSavepointId( $fname );
3814                                 $this->doSavepoint( $savepointId, $fname );
3815                         } else {
3816                                 $this->trxAutomaticAtomic = true;
3817                         }
3818                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3819                         $savepointId = $this->nextSavepointId( $fname );
3820                         $this->doSavepoint( $savepointId, $fname );
3821                 }
3822
3823                 $sectionId = new AtomicSectionIdentifier;
3824                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3825                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3826                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3827
3828                 return $sectionId;
3829         }
3830
3831         final public function endAtomic( $fname = __METHOD__ ) {
3832                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3833                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3834                 }
3835
3836                 // Check if the current section matches $fname
3837                 $pos = count( $this->trxAtomicLevels ) - 1;
3838                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3839                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3840
3841                 if ( $savedFname !== $fname ) {
3842                         throw new DBUnexpectedError(
3843                                 $this,
3844                                 "Invalid atomic section ended (got $fname but expected $savedFname)"
3845                         );
3846                 }
3847
3848                 // Remove the last section (no need to re-index the array)
3849                 array_pop( $this->trxAtomicLevels );
3850
3851                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3852                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3853                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3854                         $this->doReleaseSavepoint( $savepointId, $fname );
3855                 }
3856
3857                 // Hoist callback ownership for callbacks in the section that just ended;
3858                 // all callbacks should have an owner that is present in trxAtomicLevels.
3859                 $currentSectionId = $this->currentAtomicSectionId();
3860                 if ( $currentSectionId ) {
3861                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3862                 }
3863         }
3864
3865         final public function cancelAtomic(
3866                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3867         ) {
3868                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3869                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3870                 }
3871
3872                 $excisedIds = [];
3873                 $newTopSection = $this->currentAtomicSectionId();
3874                 try {
3875                         $excisedFnames = [];
3876                         if ( $sectionId !== null ) {
3877                                 // Find the (last) section with the given $sectionId
3878                                 $pos = -1;
3879                                 foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3880                                         if ( $asId === $sectionId ) {
3881                                                 $pos = $i;
3882                                         }
3883                                 }
3884                                 if ( $pos < 0 ) {
3885                                         throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3886                                 }
3887                                 // Remove all descendant sections and re-index the array
3888                                 $len = count( $this->trxAtomicLevels );
3889                                 for ( $i = $pos + 1; $i < $len; ++$i ) {
3890                                         $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3891                                         $excisedIds[] = $this->trxAtomicLevels[$i][1];
3892                                 }
3893                                 $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3894                                 $newTopSection = $this->currentAtomicSectionId();
3895                         }
3896
3897                         // Check if the current section matches $fname
3898                         $pos = count( $this->trxAtomicLevels ) - 1;
3899                         list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3900
3901                         if ( $excisedFnames ) {
3902                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3903                                         "and descendants " . implode( ', ', $excisedFnames ) );
3904                         } else {
3905                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3906                         }
3907
3908                         if ( $savedFname !== $fname ) {
3909                                 throw new DBUnexpectedError(
3910                                         $this,
3911                                         "Invalid atomic section ended (got $fname but expected $savedFname)"
3912                                 );
3913                         }
3914
3915                         // Remove the last section (no need to re-index the array)
3916                         array_pop( $this->trxAtomicLevels );
3917                         $excisedIds[] = $savedSectionId;
3918                         $newTopSection = $this->currentAtomicSectionId();
3919
3920                         if ( $savepointId !== null ) {
3921                                 // Rollback the transaction to the state just before this atomic section
3922                                 if ( $savepointId === self::$NOT_APPLICABLE ) {
3923                                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3924                                         // Note: rollback() will run trxSectionCancelCallbacks
3925                                 } else {
3926                                         $this->doRollbackToSavepoint( $savepointId, $fname );
3927                                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3928                                         $this->trxStatusIgnoredCause = null;
3929
3930                                         // Run trxSectionCancelCallbacks now.
3931                                         $this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
3932                                 }
3933                         } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3934                                 // Put the transaction into an error state if it's not already in one
3935                                 $this->trxStatus = self::STATUS_TRX_ERROR;
3936                                 $this->trxStatusCause = new DBUnexpectedError(
3937                                         $this,
3938                                         "Uncancelable atomic section canceled (got $fname)"
3939                                 );
3940                         }
3941                 } finally {
3942                         // Fix up callbacks owned by the sections that were just cancelled.
3943                         // All callbacks should have an owner that is present in trxAtomicLevels.
3944                         $this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
3945                 }
3946
3947                 $this->affectedRowCount = 0; // for the sake of consistency
3948         }
3949
3950         final public function doAtomicSection(
3951                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3952         ) {
3953                 $sectionId = $this->startAtomic( $fname, $cancelable );
3954                 try {
3955                         $res = $callback( $this, $fname );
3956                 } catch ( Exception $e ) {
3957                         $this->cancelAtomic( $fname, $sectionId );
3958
3959                         throw $e;
3960                 }
3961                 $this->endAtomic( $fname );
3962
3963                 return $res;
3964         }
3965
3966         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3967                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3968                 if ( !in_array( $mode, $modes, true ) ) {
3969                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'" );
3970                 }
3971
3972                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3973                 if ( $this->trxLevel() ) {
3974                         if ( $this->trxAtomicLevels ) {
3975                                 $levels = $this->flatAtomicSectionList();
3976                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open";
3977                                 throw new DBUnexpectedError( $this, $msg );
3978                         } elseif ( !$this->trxAutomatic ) {
3979                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname})";
3980                                 throw new DBUnexpectedError( $this, $msg );
3981                         } else {
3982                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname})";
3983                                 throw new DBUnexpectedError( $this, $msg );
3984                         }
3985                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3986                         $msg = "$fname: Implicit transaction expected (DBO_TRX set)";
3987                         throw new DBUnexpectedError( $this, $msg );
3988                 }
3989
3990                 $this->assertHasConnectionHandle();
3991
3992                 $this->doBegin( $fname );
3993                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3994                 $this->trxStatus = self::STATUS_TRX_OK;
3995                 $this->trxStatusIgnoredCause = null;
3996                 $this->trxAtomicCounter = 0;
3997                 $this->trxTimestamp = microtime( true );
3998                 $this->trxFname = $fname;
3999                 $this->trxDoneWrites = false;
4000                 $this->trxAutomaticAtomic = false;
4001                 $this->trxAtomicLevels = [];
4002                 $this->trxWriteDuration = 0.0;
4003                 $this->trxWriteQueryCount = 0;
4004                 $this->trxWriteAffectedRows = 0;
4005                 $this->trxWriteAdjDuration = 0.0;
4006                 $this->trxWriteAdjQueryCount = 0;
4007                 $this->trxWriteCallers = [];
4008                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
4009                 // Get an estimate of the replication lag before any such queries.
4010                 $this->trxReplicaLag = null; // clear cached value first
4011                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
4012                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
4013                 // caller will think its OK to muck around with the transaction just because startAtomic()
4014                 // has not yet completed (e.g. setting trxAtomicLevels).
4015                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
4016         }
4017
4018         /**
4019          * Issues the BEGIN command to the database server.
4020          *
4021          * @see Database::begin()
4022          * @param string $fname
4023          * @throws DBError
4024          */
4025         protected function doBegin( $fname ) {
4026                 $this->query( 'BEGIN', $fname );
4027         }
4028
4029         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4030                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
4031                 if ( !in_array( $flush, $modes, true ) ) {
4032                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'" );
4033                 }
4034
4035                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
4036                         // There are still atomic sections open; this cannot be ignored
4037                         $levels = $this->flatAtomicSectionList();
4038                         throw new DBUnexpectedError(
4039                                 $this,
4040                                 "$fname: Got COMMIT while atomic sections $levels are still open"
4041                         );
4042                 }
4043
4044                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
4045                         if ( !$this->trxLevel() ) {
4046                                 return; // nothing to do
4047                         } elseif ( !$this->trxAutomatic ) {
4048                                 throw new DBUnexpectedError(
4049                                         $this,
4050                                         "$fname: Flushing an explicit transaction, getting out of sync"
4051                                 );
4052                         }
4053                 } elseif ( !$this->trxLevel() ) {
4054                         $this->queryLogger->error(
4055                                 "$fname: No transaction to commit, something got out of sync" );
4056                         return; // nothing to do
4057                 } elseif ( $this->trxAutomatic ) {
4058                         throw new DBUnexpectedError(
4059                                 $this,
4060                                 "$fname: Expected mass commit of all peer transactions (DBO_TRX set)"
4061                         );
4062                 }
4063
4064                 $this->assertHasConnectionHandle();
4065
4066                 $this->runOnTransactionPreCommitCallbacks();
4067
4068                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
4069                 $this->doCommit( $fname );
4070                 $oldTrxShortId = $this->consumeTrxShortId();
4071                 $this->trxStatus = self::STATUS_TRX_NONE;
4072
4073                 if ( $this->trxDoneWrites ) {
4074                         $this->lastWriteTime = microtime( true );
4075                         $this->trxProfiler->transactionWritingOut(
4076                                 $this->server,
4077                                 $this->getDomainID(),
4078                                 $oldTrxShortId,
4079                                 $writeTime,
4080                                 $this->trxWriteAffectedRows
4081                         );
4082                 }
4083
4084                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4085                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
4086                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
4087                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
4088                 }
4089         }
4090
4091         /**
4092          * Issues the COMMIT command to the database server.
4093          *
4094          * @see Database::commit()
4095          * @param string $fname
4096          * @throws DBError
4097          */
4098         protected function doCommit( $fname ) {
4099                 if ( $this->trxLevel() ) {
4100                         $this->query( 'COMMIT', $fname );
4101                 }
4102         }
4103
4104         final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4105                 $trxActive = $this->trxLevel();
4106
4107                 if ( $flush !== self::FLUSHING_INTERNAL
4108                         && $flush !== self::FLUSHING_ALL_PEERS
4109                         && $this->getFlag( self::DBO_TRX )
4110                 ) {
4111                         throw new DBUnexpectedError(
4112                                 $this,
4113                                 "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)"
4114                         );
4115                 }
4116
4117                 if ( $trxActive ) {
4118                         $this->assertHasConnectionHandle();
4119
4120                         $this->doRollback( $fname );
4121                         $oldTrxShortId = $this->consumeTrxShortId();
4122                         $this->trxStatus = self::STATUS_TRX_NONE;
4123                         $this->trxAtomicLevels = [];
4124                         // Estimate the RTT via a query now that trxStatus is OK
4125                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4126
4127                         if ( $this->trxDoneWrites ) {
4128                                 $this->trxProfiler->transactionWritingOut(
4129                                         $this->server,
4130                                         $this->getDomainID(),
4131                                         $oldTrxShortId,
4132                                         $writeTime,
4133                                         $this->trxWriteAffectedRows
4134                                 );
4135                         }
4136                 }
4137
4138                 // Clear any commit-dependant callbacks. They might even be present
4139                 // only due to transaction rounds, with no SQL transaction being active
4140                 $this->trxIdleCallbacks = [];
4141                 $this->trxPreCommitCallbacks = [];
4142
4143                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4144                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4145                         try {
4146                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4147                         } catch ( Exception $e ) {
4148                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4149                         }
4150                         try {
4151                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4152                         } catch ( Exception $e ) {
4153                                 // already logged; let LoadBalancer move on during mass-rollback
4154                         }
4155
4156                         $this->affectedRowCount = 0; // for the sake of consistency
4157                 }
4158         }
4159
4160         /**
4161          * Issues the ROLLBACK command to the database server.
4162          *
4163          * @see Database::rollback()
4164          * @param string $fname
4165          * @throws DBError
4166          */
4167         protected function doRollback( $fname ) {
4168                 if ( $this->trxLevel() ) {
4169                         # Disconnects cause rollback anyway, so ignore those errors
4170                         $ignoreErrors = true;
4171                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4172                 }
4173         }
4174
4175         public function flushSnapshot( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4176                 if ( $this->explicitTrxActive() ) {
4177                         // Committing this transaction would break callers that assume it is still open
4178                         throw new DBUnexpectedError(
4179                                 $this,
4180                                 "$fname: Cannot flush snapshot; " .
4181                                 "explicit transaction '{$this->trxFname}' is still open"
4182                         );
4183                 } elseif ( $this->writesOrCallbacksPending() ) {
4184                         // This only flushes transactions to clear snapshots, not to write data
4185                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4186                         throw new DBUnexpectedError(
4187                                 $this,
4188                                 "$fname: Cannot flush snapshot; " .
4189                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4190                         );
4191                 } elseif (
4192                         $this->trxLevel() &&
4193                         $this->getTransactionRoundId() &&
4194                         $flush !== self::FLUSHING_INTERNAL &&
4195                         $flush !== self::FLUSHING_ALL_PEERS
4196                 ) {
4197                         $this->queryLogger->warning(
4198                                 "$fname: Expected mass snapshot flush of all peer transactions " .
4199                                 "in the explicit transactions round '{$this->getTransactionRoundId()}'",
4200                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4201                         );
4202                 }
4203
4204                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4205         }
4206
4207         public function explicitTrxActive() {
4208                 return $this->trxLevel() && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4209         }
4210
4211         public function duplicateTableStructure(
4212                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4213         ) {
4214                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4215         }
4216
4217         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4218                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4219         }
4220
4221         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4222                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4223         }
4224
4225         public function timestamp( $ts = 0 ) {
4226                 $t = new ConvertibleTimestamp( $ts );
4227                 // Let errors bubble up to avoid putting garbage in the DB
4228                 return $t->getTimestamp( TS_MW );
4229         }
4230
4231         public function timestampOrNull( $ts = null ) {
4232                 if ( is_null( $ts ) ) {
4233                         return null;
4234                 } else {
4235                         return $this->timestamp( $ts );
4236                 }
4237         }
4238
4239         public function affectedRows() {
4240                 return ( $this->affectedRowCount === null )
4241                         ? $this->fetchAffectedRowCount() // default to driver value
4242                         : $this->affectedRowCount;
4243         }
4244
4245         /**
4246          * @return int Number of retrieved rows according to the driver
4247          */
4248         abstract protected function fetchAffectedRowCount();
4249
4250         /**
4251          * Take a query result and wrap it in an iterable result wrapper if necessary.
4252          * Booleans are passed through as-is to indicate success/failure of write queries.
4253          *
4254          * Once upon a time, Database::query() returned a bare MySQL result
4255          * resource, and it was necessary to call this function to convert it to
4256          * a wrapper. Nowadays, raw database objects are never exposed to external
4257          * callers, so this is unnecessary in external code.
4258          *
4259          * @param bool|IResultWrapper|resource $result
4260          * @return bool|IResultWrapper
4261          */
4262         protected function resultObject( $result ) {
4263                 if ( !$result ) {
4264                         return false; // failed query
4265                 } elseif ( $result instanceof IResultWrapper ) {
4266                         return $result;
4267                 } elseif ( $result === true ) {
4268                         return $result; // succesful write query
4269                 } else {
4270                         return new ResultWrapper( $this, $result );
4271                 }
4272         }
4273
4274         public function ping( &$rtt = null ) {
4275                 // Avoid hitting the server if it was hit recently
4276                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::$PING_TTL ) {
4277                         if ( !func_num_args() || $this->lastRoundTripEstimate > 0 ) {
4278                                 $rtt = $this->lastRoundTripEstimate;
4279                                 return true; // don't care about $rtt
4280                         }
4281                 }
4282
4283                 // This will reconnect if possible or return false if not
4284                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4285                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, true ) !== false );
4286                 $this->restoreFlags( self::RESTORE_PRIOR );
4287
4288                 if ( $ok ) {
4289                         $rtt = $this->lastRoundTripEstimate;
4290                 }
4291
4292                 return $ok;
4293         }
4294
4295         /**
4296          * Close any existing (dead) database connection and open a new connection
4297          *
4298          * @param string $fname
4299          * @return bool True if new connection is opened successfully, false if error
4300          */
4301         protected function replaceLostConnection( $fname ) {
4302                 $this->closeConnection();
4303                 $this->conn = null;
4304
4305                 $this->handleSessionLossPreconnect();
4306
4307                 try {
4308                         $this->open(
4309                                 $this->server,
4310                                 $this->user,
4311                                 $this->password,
4312                                 $this->currentDomain->getDatabase(),
4313                                 $this->currentDomain->getSchema(),
4314                                 $this->tablePrefix()
4315                         );
4316                         $this->lastPing = microtime( true );
4317                         $ok = true;
4318
4319                         $this->connLogger->warning(
4320                                 $fname . ': lost connection to {dbserver}; reconnected',
4321                                 [
4322                                         'dbserver' => $this->getServer(),
4323                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4324                                 ]
4325                         );
4326                 } catch ( DBConnectionError $e ) {
4327                         $ok = false;
4328
4329                         $this->connLogger->error(
4330                                 $fname . ': lost connection to {dbserver} permanently',
4331                                 [ 'dbserver' => $this->getServer() ]
4332                         );
4333                 }
4334
4335                 $this->handleSessionLossPostconnect();
4336
4337                 return $ok;
4338         }
4339
4340         public function getSessionLagStatus() {
4341                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4342         }
4343
4344         /**
4345          * Get the replica DB lag when the current transaction started
4346          *
4347          * This is useful when transactions might use snapshot isolation
4348          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4349          * is this lag plus transaction duration. If they don't, it is still
4350          * safe to be pessimistic. This returns null if there is no transaction.
4351          *
4352          * This returns null if the lag status for this transaction was not yet recorded.
4353          *
4354          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4355          * @since 1.27
4356          */
4357         final protected function getRecordedTransactionLagStatus() {
4358                 return ( $this->trxLevel() && $this->trxReplicaLag !== null )
4359                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4360                         : null;
4361         }
4362
4363         /**
4364          * Get a replica DB lag estimate for this server
4365          *
4366          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4367          * @since 1.27
4368          */
4369         protected function getApproximateLagStatus() {
4370                 return [
4371                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4372                         'since' => microtime( true )
4373                 ];
4374         }
4375
4376         /**
4377          * Merge the result of getSessionLagStatus() for several DBs
4378          * using the most pessimistic values to estimate the lag of
4379          * any data derived from them in combination
4380          *
4381          * This is information is useful for caching modules
4382          *
4383          * @see WANObjectCache::set()
4384          * @see WANObjectCache::getWithSetCallback()
4385          *
4386          * @param IDatabase $db1
4387          * @param IDatabase|null $db2 [optional]
4388          * @return array Map of values:
4389          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4390          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4391          *   - pending: whether any of the DBs have uncommitted changes
4392          * @throws DBError
4393          * @since 1.27
4394          */
4395         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4396                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4397                 foreach ( func_get_args() as $db ) {
4398                         /** @var IDatabase $db */
4399                         $status = $db->getSessionLagStatus();
4400                         if ( $status['lag'] === false ) {
4401                                 $res['lag'] = false;
4402                         } elseif ( $res['lag'] !== false ) {
4403                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4404                         }
4405                         $res['since'] = min( $res['since'], $status['since'] );
4406                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4407                 }
4408
4409                 return $res;
4410         }
4411
4412         public function getLag() {
4413                 if ( $this->getLBInfo( 'master' ) ) {
4414                         return 0; // this is the master
4415                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4416                         return 0; // static dataset
4417                 }
4418
4419                 return $this->doGetLag();
4420         }
4421
4422         protected function doGetLag() {
4423                 return 0;
4424         }
4425
4426         public function maxListLen() {
4427                 return 0;
4428         }
4429
4430         public function encodeBlob( $b ) {
4431                 return $b;
4432         }
4433
4434         public function decodeBlob( $b ) {
4435                 if ( $b instanceof Blob ) {
4436                         $b = $b->fetch();
4437                 }
4438                 return $b;
4439         }
4440
4441         public function setSessionOptions( array $options ) {
4442         }
4443
4444         public function sourceFile(
4445                 $filename,
4446                 callable $lineCallback = null,
4447                 callable $resultCallback = null,
4448                 $fname = false,
4449                 callable $inputCallback = null
4450         ) {
4451                 AtEase::suppressWarnings();
4452                 $fp = fopen( $filename, 'r' );
4453                 AtEase::restoreWarnings();
4454
4455                 if ( $fp === false ) {
4456                         throw new RuntimeException( "Could not open \"{$filename}\"" );
4457                 }
4458
4459                 if ( !$fname ) {
4460                         $fname = __METHOD__ . "( $filename )";
4461                 }
4462
4463                 try {
4464                         $error = $this->sourceStream(
4465                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4466                 } catch ( Exception $e ) {
4467                         fclose( $fp );
4468                         throw $e;
4469                 }
4470
4471                 fclose( $fp );
4472
4473                 return $error;
4474         }
4475
4476         public function setSchemaVars( $vars ) {
4477                 $this->schemaVars = $vars;
4478         }
4479
4480         public function sourceStream(
4481                 $fp,
4482                 callable $lineCallback = null,
4483                 callable $resultCallback = null,
4484                 $fname = __METHOD__,
4485                 callable $inputCallback = null
4486         ) {
4487                 $delimiterReset = new ScopedCallback(
4488                         function ( $delimiter ) {
4489                                 $this->delimiter = $delimiter;
4490                         },
4491                         [ $this->delimiter ]
4492                 );
4493                 $cmd = '';
4494
4495                 while ( !feof( $fp ) ) {
4496                         if ( $lineCallback ) {
4497                                 call_user_func( $lineCallback );
4498                         }
4499
4500                         $line = trim( fgets( $fp ) );
4501
4502                         if ( $line == '' ) {
4503                                 continue;
4504                         }
4505
4506                         if ( $line[0] == '-' && $line[1] == '-' ) {
4507                                 continue;
4508                         }
4509
4510                         if ( $cmd != '' ) {
4511                                 $cmd .= ' ';
4512                         }
4513
4514                         $done = $this->streamStatementEnd( $cmd, $line );
4515
4516                         $cmd .= "$line\n";
4517
4518                         if ( $done || feof( $fp ) ) {
4519                                 $cmd = $this->replaceVars( $cmd );
4520
4521                                 if ( $inputCallback ) {
4522                                         $callbackResult = $inputCallback( $cmd );
4523
4524                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4525                                                 $cmd = $callbackResult;
4526                                         }
4527                                 }
4528
4529                                 if ( $cmd ) {
4530                                         $res = $this->query( $cmd, $fname );
4531
4532                                         if ( $resultCallback ) {
4533                                                 $resultCallback( $res, $this );
4534                                         }
4535
4536                                         if ( $res === false ) {
4537                                                 $err = $this->lastError();
4538
4539                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4540                                         }
4541                                 }
4542                                 $cmd = '';
4543                         }
4544                 }
4545
4546                 ScopedCallback::consume( $delimiterReset );
4547                 return true;
4548         }
4549
4550         /**
4551          * Called by sourceStream() to check if we've reached a statement end
4552          *
4553          * @param string &$sql SQL assembled so far
4554          * @param string &$newLine New line about to be added to $sql
4555          * @return bool Whether $newLine contains end of the statement
4556          */
4557         public function streamStatementEnd( &$sql, &$newLine ) {
4558                 if ( $this->delimiter ) {
4559                         $prev = $newLine;
4560                         $newLine = preg_replace(
4561                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4562                         if ( $newLine != $prev ) {
4563                                 return true;
4564                         }
4565                 }
4566
4567                 return false;
4568         }
4569
4570         /**
4571          * Database independent variable replacement. Replaces a set of variables
4572          * in an SQL statement with their contents as given by $this->getSchemaVars().
4573          *
4574          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4575          *
4576          * - '{$var}' should be used for text and is passed through the database's
4577          *   addQuotes method.
4578          * - `{$var}` should be used for identifiers (e.g. table and database names).
4579          *   It is passed through the database's addIdentifierQuotes method which
4580          *   can be overridden if the database uses something other than backticks.
4581          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4582          *   database's tableName method.
4583          * - / *i* / passes the name that follows through the database's indexName method.
4584          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4585          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4586          *
4587          * @param string $ins SQL statement to replace variables in
4588          * @return string The new SQL statement with variables replaced
4589          */
4590         protected function replaceVars( $ins ) {
4591                 $vars = $this->getSchemaVars();
4592                 return preg_replace_callback(
4593                         '!
4594                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4595                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4596                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4597                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4598                         !x',
4599                         function ( $m ) use ( $vars ) {
4600                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4601                                 // check for both nonexistent keys *and* the empty string.
4602                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4603                                         if ( $m[1] === 'i' ) {
4604                                                 return $this->indexName( $m[2] );
4605                                         } else {
4606                                                 return $this->tableName( $m[2] );
4607                                         }
4608                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4609                                         return $this->addQuotes( $vars[$m[3]] );
4610                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4611                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4612                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4613                                         return $vars[$m[5]];
4614                                 } else {
4615                                         return $m[0];
4616                                 }
4617                         },
4618                         $ins
4619                 );
4620         }
4621
4622         /**
4623          * Get schema variables. If none have been set via setSchemaVars(), then
4624          * use some defaults from the current object.
4625          *
4626          * @return array
4627          */
4628         protected function getSchemaVars() {
4629                 if ( $this->schemaVars ) {
4630                         return $this->schemaVars;
4631                 } else {
4632                         return $this->getDefaultSchemaVars();
4633                 }
4634         }
4635
4636         /**
4637          * Get schema variables to use if none have been set via setSchemaVars().
4638          *
4639          * Override this in derived classes to provide variables for tables.sql
4640          * and SQL patch files.
4641          *
4642          * @return array
4643          */
4644         protected function getDefaultSchemaVars() {
4645                 return [];
4646         }
4647
4648         public function lockIsFree( $lockName, $method ) {
4649                 // RDBMs methods for checking named locks may or may not count this thread itself.
4650                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4651                 // the behavior choosen by the interface for this method.
4652                 return !isset( $this->sessionNamedLocks[$lockName] );
4653         }
4654
4655         public function lock( $lockName, $method, $timeout = 5 ) {
4656                 $this->sessionNamedLocks[$lockName] = 1;
4657
4658                 return true;
4659         }
4660
4661         public function unlock( $lockName, $method ) {
4662                 unset( $this->sessionNamedLocks[$lockName] );
4663
4664                 return true;
4665         }
4666
4667         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4668                 if ( $this->writesOrCallbacksPending() ) {
4669                         // This only flushes transactions to clear snapshots, not to write data
4670                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4671                         throw new DBUnexpectedError(
4672                                 $this,
4673                                 "$fname: Cannot flush pre-lock snapshot; " .
4674                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4675                         );
4676                 }
4677
4678                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4679                         return null;
4680                 }
4681
4682                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4683                         if ( $this->trxLevel() ) {
4684                                 // There is a good chance an exception was thrown, causing any early return
4685                                 // from the caller. Let any error handler get a chance to issue rollback().
4686                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4687                                 $this->onTransactionResolution(
4688                                         function () use ( $lockKey, $fname ) {
4689                                                 $this->unlock( $lockKey, $fname );
4690                                         },
4691                                         $fname
4692                                 );
4693                         } else {
4694                                 $this->unlock( $lockKey, $fname );
4695                         }
4696                 } );
4697
4698                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4699
4700                 return $unlocker;
4701         }
4702
4703         public function namedLocksEnqueue() {
4704                 return false;
4705         }
4706
4707         public function tableLocksHaveTransactionScope() {
4708                 return true;
4709         }
4710
4711         final public function lockTables( array $read, array $write, $method ) {
4712                 if ( $this->writesOrCallbacksPending() ) {
4713                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending" );
4714                 }
4715
4716                 if ( $this->tableLocksHaveTransactionScope() ) {
4717                         $this->startAtomic( $method );
4718                 }
4719
4720                 return $this->doLockTables( $read, $write, $method );
4721         }
4722
4723         /**
4724          * Helper function for lockTables() that handles the actual table locking
4725          *
4726          * @param array $read Array of tables to lock for read access
4727          * @param array $write Array of tables to lock for write access
4728          * @param string $method Name of caller
4729          * @return true
4730          */
4731         protected function doLockTables( array $read, array $write, $method ) {
4732                 return true;
4733         }
4734
4735         final public function unlockTables( $method ) {
4736                 if ( $this->tableLocksHaveTransactionScope() ) {
4737                         $this->endAtomic( $method );
4738
4739                         return true; // locks released on COMMIT/ROLLBACK
4740                 }
4741
4742                 return $this->doUnlockTables( $method );
4743         }
4744
4745         /**
4746          * Helper function for unlockTables() that handles the actual table unlocking
4747          *
4748          * @param string $method Name of caller
4749          * @return true
4750          */
4751         protected function doUnlockTables( $method ) {
4752                 return true;
4753         }
4754
4755         /**
4756          * Delete a table
4757          * @param string $tableName
4758          * @param string $fName
4759          * @return bool|IResultWrapper
4760          * @since 1.18
4761          */
4762         public function dropTable( $tableName, $fName = __METHOD__ ) {
4763                 if ( !$this->tableExists( $tableName, $fName ) ) {
4764                         return false;
4765                 }
4766                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4767
4768                 return $this->query( $sql, $fName );
4769         }
4770
4771         public function getInfinity() {
4772                 return 'infinity';
4773         }
4774
4775         public function encodeExpiry( $expiry ) {
4776                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4777                         ? $this->getInfinity()
4778                         : $this->timestamp( $expiry );
4779         }
4780
4781         public function decodeExpiry( $expiry, $format = TS_MW ) {
4782                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4783                         return 'infinity';
4784                 }
4785
4786                 return ConvertibleTimestamp::convert( $format, $expiry );
4787         }
4788
4789         public function setBigSelects( $value = true ) {
4790                 // no-op
4791         }
4792
4793         public function isReadOnly() {
4794                 return ( $this->getReadOnlyReason() !== false );
4795         }
4796
4797         /**
4798          * @return string|bool Reason this DB is read-only or false if it is not
4799          */
4800         protected function getReadOnlyReason() {
4801                 $reason = $this->getLBInfo( 'readOnlyReason' );
4802                 if ( is_string( $reason ) ) {
4803                         return $reason;
4804                 } elseif ( $this->getLBInfo( 'replica' ) ) {
4805                         return "Server is configured in the role of a read-only replica database.";
4806                 }
4807
4808                 return false;
4809         }
4810
4811         public function setTableAliases( array $aliases ) {
4812                 $this->tableAliases = $aliases;
4813         }
4814
4815         public function setIndexAliases( array $aliases ) {
4816                 $this->indexAliases = $aliases;
4817         }
4818
4819         /**
4820          * @param int $field
4821          * @param int $flags
4822          * @return bool
4823          */
4824         protected function hasFlags( $field, $flags ) {
4825                 return ( ( $field & $flags ) === $flags );
4826         }
4827
4828         /**
4829          * Get the underlying binding connection handle
4830          *
4831          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4832          * This catches broken callers than catch and ignore disconnection exceptions.
4833          * Unlike checking isOpen(), this is safe to call inside of open().
4834          *
4835          * @return mixed
4836          * @throws DBUnexpectedError
4837          * @since 1.26
4838          */
4839         protected function getBindingHandle() {
4840                 if ( !$this->conn ) {
4841                         throw new DBUnexpectedError(
4842                                 $this,
4843                                 'DB connection was already closed or the connection dropped'
4844                         );
4845                 }
4846
4847                 return $this->conn;
4848         }
4849
4850         public function __toString() {
4851                 // spl_object_id is PHP >= 7.2
4852                 $id = function_exists( 'spl_object_id' )
4853                         ? spl_object_id( $this )
4854                         : spl_object_hash( $this );
4855
4856                 $description = $this->getType() . ' object #' . $id;
4857                 if ( is_resource( $this->conn ) ) {
4858                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4859                 } elseif ( is_object( $this->conn ) ) {
4860                         // spl_object_id is PHP >= 7.2
4861                         $handleId = function_exists( 'spl_object_id' )
4862                                 ? spl_object_id( $this->conn )
4863                                 : spl_object_hash( $this->conn );
4864                         $description .= " (handle id #$handleId)";
4865                 }
4866
4867                 return $description;
4868         }
4869
4870         /**
4871          * Make sure that copies do not share the same client binding handle
4872          * @throws DBConnectionError
4873          */
4874         public function __clone() {
4875                 $this->connLogger->warning(
4876                         "Cloning " . static::class . " is not recommended; forking connection",
4877                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4878                 );
4879
4880                 if ( $this->isOpen() ) {
4881                         // Open a new connection resource without messing with the old one
4882                         $this->conn = null;
4883                         $this->trxEndCallbacks = []; // don't copy
4884                         $this->trxSectionCancelCallbacks = []; // don't copy
4885                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4886                         $this->open(
4887                                 $this->server,
4888                                 $this->user,
4889                                 $this->password,
4890                                 $this->currentDomain->getDatabase(),
4891                                 $this->currentDomain->getSchema(),
4892                                 $this->tablePrefix()
4893                         );
4894                         $this->lastPing = microtime( true );
4895                 }
4896         }
4897
4898         /**
4899          * Called by serialize. Throw an exception when DB connection is serialized.
4900          * This causes problems on some database engines because the connection is
4901          * not restored on unserialize.
4902          */
4903         public function __sleep() {
4904                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4905                         'the connection is not restored on wakeup' );
4906         }
4907
4908         /**
4909          * Run a few simple sanity checks and close dangling connections
4910          */
4911         public function __destruct() {
4912                 if ( $this->trxLevel() && $this->trxDoneWrites ) {
4913                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})" );
4914                 }
4915
4916                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4917                 if ( $danglingWriters ) {
4918                         $fnames = implode( ', ', $danglingWriters );
4919                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)" );
4920                 }
4921
4922                 if ( $this->conn ) {
4923                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4924                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4925                         AtEase::suppressWarnings();
4926                         $this->closeConnection();
4927                         AtEase::restoreWarnings();
4928                         $this->conn = null;
4929                 }
4930         }
4931 }
4932
4933 /**
4934  * @deprecated since 1.28
4935  */
4936 class_alias( Database::class, 'DatabaseBase' );
4937
4938 /**
4939  * @deprecated since 1.29
4940  */
4941 class_alias( Database::class, 'Database' );