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
 254                 $this->connectionVariables = $params['variables'];
 255
 256                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 257
 258                 $this->profiler = is_callable( $params['profiler'] ) ? $params['profiler'] : null;
 259                 $this->trxProfiler = $params['trxProfiler'];
 260                 $this->connLogger = $params['connLogger'];
 261                 $this->queryLogger = $params['queryLogger'];
 262                 $this->errorLogger = $params['errorLogger'];
 263                 $this->deprecationLogger = $params['deprecationLogger'];
 264
 265                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 266                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 267                 }
 268
 269                 // Set initial dummy domain until open() sets the final DB/prefix
 270                 $this->currentDomain = new DatabaseDomain(
 271                         $params['dbname'] != '' ? $params['dbname'] : null,
 272                         $params['schema'] != '' ? $params['schema'] : null,
 273                         $params['tablePrefix']
 274                 );
 275         }
 276
 277         /**
 278          * Initialize the connection to the database over the wire (or to local files)
 279          *
 280          * @throws LogicException
 281          * @throws InvalidArgumentException
 282          * @throws DBConnectionError
 283          * @since 1.31
 284          */
 285         final public function initConnection() {
 286                 if ( $this->isOpen() ) {
 287                         throw new LogicException( __METHOD__ . ': already connected' );
 288                 }
 289                 // Establish the connection
 290                 $this->doInitConnection();
 291         }
 292
 293         /**
 294          * Actually connect to the database over the wire (or to local files)
 295          *
 296          * @throws DBConnectionError
 297          * @since 1.31
 298          */
 299         protected function doInitConnection() {
 300                 $this->open(
 301                         $this->connectionParams['host'],
 302                         $this->connectionParams['user'],
 303                         $this->connectionParams['password'],
 304                         $this->connectionParams['dbname'],
 305                         $this->connectionParams['schema'],
 306                         $this->connectionParams['tablePrefix']
 307                 );
 308         }
 309
 310         /**
 311          * Open a new connection to the database (closing any existing one)
 312          *
 313          * @param string|null $server Database server host
 314          * @param string|null $user Database user name
 315          * @param string|null $password Database user password
 316          * @param string|null $dbName Database name
 317          * @param string|null $schema Database schema name
 318          * @param string $tablePrefix Table prefix
 319          * @throws DBConnectionError
 320          */
 321         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 322
 323         /**
 324          * Construct a Database subclass instance given a database type and parameters
 325          *
 326          * This also connects to the database immediately upon object construction
 327          *
 328          * @param string $type A possible DB type (sqlite, mysql, postgres,...)
 329          * @param array $params Parameter map with keys:
 330          *   - host : The hostname of the DB server
 331          *   - user : The name of the database user the client operates under
 332          *   - password : The password for the database user
 333          *   - dbname : The name of the database to use where queries do not specify one.
 334          *      The database must exist or an error might be thrown. Setting this to the empty string
 335          *      will avoid any such errors and make the handle have no implicit database scope. This is
 336          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 337          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 338          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 339          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 340          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 341          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 342          *      recognized in queries. This can be used in place of schemas for handle site farms.
 343          *   - flags : Optional bit field of DBO_* constants that define connection, protocol,
 344          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 345          *      flag in place UNLESS this this database simply acts as a key/value store.
 346          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 347          *      'mysqli' driver; the old one 'mysql' has been removed.
 348          *   - variables: Optional map of session variables to set after connecting. This can be
 349          *      used to adjust lock timeouts or encoding modes and the like.
 350          *   - connLogger: Optional PSR-3 logger interface instance.
 351          *   - queryLogger: Optional PSR-3 logger interface instance.
 352          *   - profiler : Optional callback that takes a section name argument and returns
 353          *      a ScopedCallback instance that ends the profile section in its destructor.
 354          *      These will be called in query(), using a simplified version of the SQL that
 355          *      also includes the agent as a SQL comment.
 356          *   - trxProfiler: Optional TransactionProfiler instance.
 357          *   - errorLogger: Optional callback that takes an Exception and logs it.
 358          *   - deprecationLogger: Optional callback that takes a string and logs it.
 359          *   - cliMode: Whether to consider the execution context that of a CLI script.
 360          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 361          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 362          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 363          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 364          * @return Database|null If the database driver or extension cannot be found
 365          * @throws InvalidArgumentException If the database driver or extension cannot be found
 366          * @since 1.18
 367          */
 368         final public static function factory( $type, $params = [], $connect = self::NEW_CONNECTED ) {
 369                 $class = self::getClass( $type, $params['driver'] ?? null );
 370
 371                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 372                         $params += [
 373                                 'host' => null,
 374                                 'user' => null,
 375                                 'password' => null,
 376                                 'dbname' => null,
 377                                 'schema' => null,
 378                                 'tablePrefix' => '',
 379                                 'flags' => 0,
 380                                 'variables' => [],
 381                                 'cliMode' => ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' ),
 382                                 'agent' => basename( $_SERVER['SCRIPT_NAME'] ) . '@' . gethostname()
 383                         ];
 384
 385                         $normalizedParams = [
 386                                 // Configuration
 387                                 'host' => strlen( $params['host'] ) ? $params['host'] : null,
 388                                 'user' => strlen( $params['user'] ) ? $params['user'] : null,
 389                                 'password' => is_string( $params['password'] ) ? $params['password'] : null,
 390                                 'dbname' => strlen( $params['dbname'] ) ? $params['dbname'] : null,
 391                                 'schema' => strlen( $params['schema'] ) ? $params['schema'] : null,
 392                                 'tablePrefix' => (string)$params['tablePrefix'],
 393                                 'flags' => (int)$params['flags'],
 394                                 'variables' => $params['variables'],
 395                                 'cliMode' => (bool)$params['cliMode'],
 396                                 'agent' => (string)$params['agent'],
 397                                 // Objects and callbacks
 398                                 'profiler' => $params['profiler'] ?? null,
 399                                 'trxProfiler' => $params['trxProfiler'] ?? new TransactionProfiler(),
 400                                 'connLogger' => $params['connLogger'] ?? new NullLogger(),
 401                                 'queryLogger' => $params['queryLogger'] ?? new NullLogger(),
 402                                 'errorLogger' => $params['errorLogger'] ?? function ( Exception $e ) {
 403                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 404                                 },
 405                                 'deprecationLogger' => $params['deprecationLogger'] ?? function ( $msg ) {
 406                                         trigger_error( $msg, E_USER_DEPRECATED );
 407                                 }
 408                         ] + $params;
 409
 410                         /** @var Database $conn */
 411                         $conn = new $class( $normalizedParams );
 412                         if ( $connect === self::NEW_CONNECTED ) {
 413                                 $conn->initConnection();
 414                         }
 415                 } else {
 416                         $conn = null;
 417                 }
 418
 419                 return $conn;
 420         }
 421
 422         /**
 423          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 424          * @param string|null $driver Optional name of a specific DB client driver
 425          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 426          * @throws InvalidArgumentException
 427          * @since 1.31
 428          */
 429         final public static function attributesFromType( $dbType, $driver = null ) {
 430                 static $defaults = [
 431                         self::ATTR_DB_LEVEL_LOCKING => false,
 432                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 433                 ];
 434
 435                 $class = self::getClass( $dbType, $driver );
 436
 437                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 438         }
 439
 440         /**
 441          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 442          * @param string|null $driver Optional name of a specific DB client driver
 443          * @return string Database subclass name to use
 444          * @throws InvalidArgumentException
 445          */
 446         private static function getClass( $dbType, $driver = null ) {
 447                 // For database types with built-in support, the below maps type to IDatabase
 448                 // implementations. For types with multipe driver implementations (PHP extensions),
 449                 // an array can be used, keyed by extension name. In case of an array, the
 450                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 451                 // we auto-detect the first available driver. For types without built-in support,
 452                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 453                 static $builtinTypes = [
 454                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 455                         'sqlite' => DatabaseSqlite::class,
 456                         'postgres' => DatabasePostgres::class,
 457                 ];
 458
 459                 $dbType = strtolower( $dbType );
 460                 $class = false;
 461
 462                 if ( isset( $builtinTypes[$dbType] ) ) {
 463                         $possibleDrivers = $builtinTypes[$dbType];
 464                         if ( is_string( $possibleDrivers ) ) {
 465                                 $class = $possibleDrivers;
 466                         } elseif ( (string)$driver !== '' ) {
 467                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 468                                         throw new InvalidArgumentException( __METHOD__ .
 469                                                 " type '$dbType' does not support driver '{$driver}'" );
 470                                 }
 471
 472                                 $class = $possibleDrivers[$driver];
 473                         } else {
 474                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 475                                         if ( extension_loaded( $posDriver ) ) {
 476                                                 $class = $possibleClass;
 477                                                 break;
 478                                         }
 479                                 }
 480                         }
 481                 } else {
 482                         $class = 'Database' . ucfirst( $dbType );
 483                 }
 484
 485                 if ( $class === false ) {
 486                         throw new InvalidArgumentException( __METHOD__ .
 487                                 " no viable database extension found for type '$dbType'" );
 488                 }
 489
 490                 return $class;
 491         }
 492
 493         /**
 494          * @return array Map of (Database::ATTR_* constant => value
 495          * @since 1.31
 496          */
 497         protected static function getAttributes() {
 498                 return [];
 499         }
 500
 501         /**
 502          * Set the PSR-3 logger interface to use for query logging. (The logger
 503          * interfaces for connection logging and error logging can be set with the
 504          * constructor.)
 505          *
 506          * @param LoggerInterface $logger
 507          */
 508         public function setLogger( LoggerInterface $logger ) {
 509                 $this->queryLogger = $logger;
 510         }
 511
 512         public function getServerInfo() {
 513                 return $this->getServerVersion();
 514         }
 515
 516         /**
 517          * Backwards-compatibility no-op method for disabling query buffering
 518          *
 519          * @param null|bool $buffer Whether to buffer queries (ignored)
 520          * @return bool Whether buffering was already enabled (always true)
 521          * @deprecated Since 1.34 Use query batching; this no longer does anything
 522          */
 523         public function bufferResults( $buffer = null ) {
 524                 return true;
 525         }
 526
 527         final public function trxLevel() {
 528                 return ( $this->trxShortId != '' ) ? 1 : 0;
 529         }
 530
 531         public function trxTimestamp() {
 532                 return $this->trxLevel() ? $this->trxTimestamp : null;
 533         }
 534
 535         /**
 536          * @return int One of the STATUS_TRX_* class constants
 537          * @since 1.31
 538          */
 539         public function trxStatus() {
 540                 return $this->trxStatus;
 541         }
 542
 543         public function tablePrefix( $prefix = null ) {
 544                 $old = $this->currentDomain->getTablePrefix();
 545                 if ( $prefix !== null ) {
 546                         $this->currentDomain = new DatabaseDomain(
 547                                 $this->currentDomain->getDatabase(),
 548                                 $this->currentDomain->getSchema(),
 549                                 $prefix
 550                         );
 551                 }
 552
 553                 return $old;
 554         }
 555
 556         public function dbSchema( $schema = null ) {
 557                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 558                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set" );
 559                 }
 560
 561                 $old = $this->currentDomain->getSchema();
 562                 if ( $schema !== null ) {
 563                         $this->currentDomain = new DatabaseDomain(
 564                                 $this->currentDomain->getDatabase(),
 565                                 // DatabaseDomain uses null for unspecified schemas
 566                                 strlen( $schema ) ? $schema : null,
 567                                 $this->currentDomain->getTablePrefix()
 568                         );
 569                 }
 570
 571                 return (string)$old;
 572         }
 573
 574         /**
 575          * @return string Schema to use to qualify relations in queries
 576          */
 577         protected function relationSchemaQualifier() {
 578                 return $this->dbSchema();
 579         }
 580
 581         public function getLBInfo( $name = null ) {
 582                 if ( is_null( $name ) ) {
 583                         return $this->lbInfo;
 584                 }
 585
 586                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 587                         return $this->lbInfo[$name];
 588                 }
 589
 590                 return null;
 591         }
 592
 593         public function setLBInfo( $nameOrArray, $value = null ) {
 594                 if ( is_array( $nameOrArray ) ) {
 595                         $this->lbInfo = $nameOrArray;
 596                 } elseif ( is_string( $nameOrArray ) ) {
 597                         if ( $value !== null ) {
 598                                 $this->lbInfo[$nameOrArray] = $value;
 599                         } else {
 600                                 unset( $this->lbInfo[$nameOrArray] );
 601                         }
 602                 } else {
 603                         throw new InvalidArgumentException( "Got non-string key" );
 604                 }
 605         }
 606
 607         public function setLazyMasterHandle( IDatabase $conn ) {
 608                 $this->lazyMasterHandle = $conn;
 609         }
 610
 611         /**
 612          * @return IDatabase|null
 613          * @see setLazyMasterHandle()
 614          * @since 1.27
 615          */
 616         protected function getLazyMasterHandle() {
 617                 return $this->lazyMasterHandle;
 618         }
 619
 620         public function implicitOrderby() {
 621                 return true;
 622         }
 623
 624         public function lastQuery() {
 625                 return $this->lastQuery;
 626         }
 627
 628         public function lastDoneWrites() {
 629                 return $this->lastWriteTime ?: false;
 630         }
 631
 632         public function writesPending() {
 633                 return $this->trxLevel() && $this->trxDoneWrites;
 634         }
 635
 636         public function writesOrCallbacksPending() {
 637                 return $this->trxLevel() && (
 638                         $this->trxDoneWrites ||
 639                         $this->trxIdleCallbacks ||
 640                         $this->trxPreCommitCallbacks ||
 641                         $this->trxEndCallbacks ||
 642                         $this->trxSectionCancelCallbacks
 643                 );
 644         }
 645
 646         public function preCommitCallbacksPending() {
 647                 return $this->trxLevel() && $this->trxPreCommitCallbacks;
 648         }
 649
 650         /**
 651          * @return string|null
 652          */
 653         final protected function getTransactionRoundId() {
 654                 // If transaction round participation is enabled, see if one is active
 655                 if ( $this->getFlag( self::DBO_TRX ) ) {
 656                         $id = $this->getLBInfo( 'trxRoundId' );
 657
 658                         return is_string( $id ) ? $id : null;
 659                 }
 660
 661                 return null;
 662         }
 663
 664         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 665                 if ( !$this->trxLevel() ) {
 666                         return false;
 667                 } elseif ( !$this->trxDoneWrites ) {
 668                         return 0.0;
 669                 }
 670
 671                 switch ( $type ) {
 672                         case self::ESTIMATE_DB_APPLY:
 673                                 return $this->pingAndCalculateLastTrxApplyTime();
 674                         default: // everything
 675                                 return $this->trxWriteDuration;
 676                 }
 677         }
 678
 679         /**
 680          * @return float Time to apply writes to replicas based on trxWrite* fields
 681          */
 682         private function pingAndCalculateLastTrxApplyTime() {
 683                 $this->ping( $rtt );
 684
 685                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 686                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 687                 // For omitted queries, make them count as something at least
 688                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 689                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 690
 691                 return $applyTime;
 692         }
 693
 694         public function pendingWriteCallers() {
 695                 return $this->trxLevel() ? $this->trxWriteCallers : [];
 696         }
 697
 698         public function pendingWriteRowsAffected() {
 699                 return $this->trxWriteAffectedRows;
 700         }
 701
 702         /**
 703          * List the methods that have write queries or callbacks for the current transaction
 704          *
 705          * This method should not be used outside of Database/LoadBalancer
 706          *
 707          * @return string[]
 708          * @since 1.32
 709          */
 710         public function pendingWriteAndCallbackCallers() {
 711                 $fnames = $this->pendingWriteCallers();
 712                 foreach ( [
 713                         $this->trxIdleCallbacks,
 714                         $this->trxPreCommitCallbacks,
 715                         $this->trxEndCallbacks,
 716                         $this->trxSectionCancelCallbacks
 717                 ] as $callbacks ) {
 718                         foreach ( $callbacks as $callback ) {
 719                                 $fnames[] = $callback[1];
 720                         }
 721                 }
 722
 723                 return $fnames;
 724         }
 725
 726         /**
 727          * @return string
 728          */
 729         private function flatAtomicSectionList() {
 730                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 731                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 732                 } );
 733         }
 734
 735         public function isOpen() {
 736                 return (bool)$this->conn;
 737         }
 738
 739         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 740                 if ( $flag & ~static::$DBO_MUTABLE ) {
 741                         throw new DBUnexpectedError(
 742                                 $this,
 743                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 744                         );
 745                 }
 746
 747                 if ( $remember === self::REMEMBER_PRIOR ) {
 748                         array_push( $this->priorFlags, $this->flags );
 749                 }
 750
 751                 $this->flags |= $flag;
 752         }
 753
 754         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 755                 if ( $flag & ~static::$DBO_MUTABLE ) {
 756                         throw new DBUnexpectedError(
 757                                 $this,
 758                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 759                         );
 760                 }
 761
 762                 if ( $remember === self::REMEMBER_PRIOR ) {
 763                         array_push( $this->priorFlags, $this->flags );
 764                 }
 765
 766                 $this->flags &= ~$flag;
 767         }
 768
 769         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 770                 if ( !$this->priorFlags ) {
 771                         return;
 772                 }
 773
 774                 if ( $state === self::RESTORE_INITIAL ) {
 775                         $this->flags = reset( $this->priorFlags );
 776                         $this->priorFlags = [];
 777                 } else {
 778                         $this->flags = array_pop( $this->priorFlags );
 779                 }
 780         }
 781
 782         public function getFlag( $flag ) {
 783                 return ( ( $this->flags & $flag ) === $flag );
 784         }
 785
 786         public function getDomainID() {
 787                 return $this->currentDomain->getId();
 788         }
 789
 790         /**
 791          * Get information about an index into an object
 792          * @param string $table Table name
 793          * @param string $index Index name
 794          * @param string $fname Calling function name
 795          * @return mixed Database-specific index description class or false if the index does not exist
 796          */
 797         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 798
 799         /**
 800          * Wrapper for addslashes()
 801          *
 802          * @param string $s String to be slashed.
 803          * @return string Slashed string.
 804          */
 805         abstract function strencode( $s );
 806
 807         /**
 808          * Set a custom error handler for logging errors during database connection
 809          */
 810         protected function installErrorHandler() {
 811                 $this->lastPhpError = false;
 812                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 813                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 814         }
 815
 816         /**
 817          * Restore the previous error handler and return the last PHP error for this DB
 818          *
 819          * @return bool|string
 820          */
 821         protected function restoreErrorHandler() {
 822                 restore_error_handler();
 823                 if ( $this->htmlErrors !== false ) {
 824                         ini_set( 'html_errors', $this->htmlErrors );
 825                 }
 826
 827                 return $this->getLastPHPError();
 828         }
 829
 830         /**
 831          * @return string|bool Last PHP error for this DB (typically connection errors)
 832          */
 833         protected function getLastPHPError() {
 834                 if ( $this->lastPhpError ) {
 835                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 836                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 837
 838                         return $error;
 839                 }
 840
 841                 return false;
 842         }
 843
 844         /**
 845          * Error handler for logging errors during database connection
 846          * This method should not be used outside of Database classes
 847          *
 848          * @param int $errno
 849          * @param string $errstr
 850          */
 851         public function connectionErrorLogger( $errno, $errstr ) {
 852                 $this->lastPhpError = $errstr;
 853         }
 854
 855         /**
 856          * Create a log context to pass to PSR-3 logger functions.
 857          *
 858          * @param array $extras Additional data to add to context
 859          * @return array
 860          */
 861         protected function getLogContext( array $extras = [] ) {
 862                 return array_merge(
 863                         [
 864                                 'db_server' => $this->server,
 865                                 'db_name' => $this->getDBname(),
 866                                 'db_user' => $this->user,
 867                         ],
 868                         $extras
 869                 );
 870         }
 871
 872         final public function close() {
 873                 $exception = null; // error to throw after disconnecting
 874
 875                 $wasOpen = (bool)$this->conn;
 876                 // This should mostly do nothing if the connection is already closed
 877                 if ( $this->conn ) {
 878                         // Roll back any dangling transaction first
 879                         if ( $this->trxLevel() ) {
 880                                 if ( $this->trxAtomicLevels ) {
 881                                         // Cannot let incomplete atomic sections be committed
 882                                         $levels = $this->flatAtomicSectionList();
 883                                         $exception = new DBUnexpectedError(
 884                                                 $this,
 885                                                 __METHOD__ . ": atomic sections $levels are still open"
 886                                         );
 887                                 } elseif ( $this->trxAutomatic ) {
 888                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 889                                         // (empty ones we can silently roll back)
 890                                         if ( $this->writesOrCallbacksPending() ) {
 891                                                 $exception = new DBUnexpectedError(
 892                                                         $this,
 893                                                         __METHOD__ .
 894                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)"
 895                                                 );
 896                                         }
 897                                 } else {
 898                                         // Manual transactions should have been committed or rolled
 899                                         // back, even if empty.
 900                                         $exception = new DBUnexpectedError(
 901                                                 $this,
 902                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})"
 903                                         );
 904                                 }
 905
 906                                 if ( $this->trxEndCallbacksSuppressed ) {
 907                                         $exception = $exception ?: new DBUnexpectedError(
 908                                                 $this,
 909                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit'
 910                                         );
 911                                 }
 912
 913                                 // Rollback the changes and run any callbacks as needed
 914                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 915                         }
 916
 917                         // Close the actual connection in the binding handle
 918                         $closed = $this->closeConnection();
 919                 } else {
 920                         $closed = true; // already closed; nothing to do
 921                 }
 922
 923                 $this->conn = null;
 924
 925                 // Throw any unexpected errors after having disconnected
 926                 if ( $exception instanceof Exception ) {
 927                         throw $exception;
 928                 }
 929
 930                 // Note that various subclasses call close() at the start of open(), which itself is
 931                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 932                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 933                 // will be executed after the reconnection step.
 934                 if ( $wasOpen ) {
 935                         // Sanity check that no callbacks are dangling
 936                         $fnames = $this->pendingWriteAndCallbackCallers();
 937                         if ( $fnames ) {
 938                                 throw new RuntimeException(
 939                                         "Transaction callbacks are still pending: " . implode( ', ', $fnames )
 940                                 );
 941                         }
 942                 }
 943
 944                 return $closed;
 945         }
 946
 947         /**
 948          * Make sure there is an open connection handle (alive or not) as a sanity check
 949          *
 950          * This guards against fatal errors to the binding handle not being defined
 951          * in cases where open() was never called or close() was already called
 952          *
 953          * @throws DBUnexpectedError
 954          */
 955         final protected function assertHasConnectionHandle() {
 956                 if ( !$this->isOpen() ) {
 957                         throw new DBUnexpectedError( $this, "DB connection was already closed" );
 958                 }
 959         }
 960
 961         /**
 962          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 963          *
 964          * @throws DBReadOnlyRoleError
 965          * @throws DBReadOnlyError
 966          */
 967         protected function assertIsWritableMaster() {
 968                 if ( $this->getLBInfo( 'replica' ) === true ) {
 969                         throw new DBReadOnlyRoleError(
 970                                 $this,
 971                                 'Write operations are not allowed on replica database connections'
 972                         );
 973                 }
 974                 $reason = $this->getReadOnlyReason();
 975                 if ( $reason !== false ) {
 976                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 977                 }
 978         }
 979
 980         /**
 981          * Closes underlying database connection
 982          * @since 1.20
 983          * @return bool Whether connection was closed successfully
 984          */
 985         abstract protected function closeConnection();
 986
 987         /**
 988          * Run a query and return a DBMS-dependent wrapper or boolean
 989          *
 990          * This is meant to handle the basic command of actually sending a query to the
 991          * server via the driver. No implicit transaction, reconnection, nor retry logic
 992          * should happen here. The higher level query() method is designed to handle those
 993          * sorts of concerns. This method should not trigger such higher level methods.
 994          *
 995          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 996          * if any, occured during the last call to this method. Methods like executeQuery(),
 997          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
 998          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
 999          * meaningfully reflects any error that occured during that public query method call.
1000          *
1001          * For SELECT queries, this returns either:
1002          *   - a) A driver-specific value/resource, only on success. This can be iterated
1003          *        over by calling fetchObject()/fetchRow() until there are no more rows.
1004          *        Alternatively, the result can be passed to resultObject() to obtain an
1005          *        IResultWrapper instance which can then be iterated over via "foreach".
1006          *   - b) False, on any query failure
1007          *
1008          * For non-SELECT queries, this returns either:
1009          *   - a) A driver-specific value/resource, only on success
1010          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1011          *   - c) False, on any query failure
1012          *
1013          * @param string $sql SQL query
1014          * @return mixed|bool An object, resource, or true on success; false on failure
1015          */
1016         abstract protected function doQuery( $sql );
1017
1018         /**
1019          * Determine whether a query writes to the DB. When in doubt, this returns true.
1020          *
1021          * Main use cases:
1022          *
1023          * - Subsequent web requests should not need to wait for replication from
1024          *   the master position seen by this web request, unless this request made
1025          *   changes to the master. This is handled by ChronologyProtector by checking
1026          *   doneWrites() at the end of the request. doneWrites() returns true if any
1027          *   query set lastWriteTime; which query() does based on isWriteQuery().
1028          *
1029          * - Reject write queries to replica DBs, in query().
1030          *
1031          * @param string $sql
1032          * @return bool
1033          */
1034         protected function isWriteQuery( $sql ) {
1035                 // BEGIN and COMMIT queries are considered read queries here.
1036                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1037                 // treat these as write queries, in that their results have "affected rows"
1038                 // as meta data as from writes, instead of "num rows" as from reads.
1039                 // But, we treat them as read queries because when reading data (from
1040                 // either replica or master) we use transactions to enable repeatable-read
1041                 // snapshots, which ensures we get consistent results from the same snapshot
1042                 // for all queries within a request. Use cases:
1043                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1044                 // - We use this method to reject writes to replicas, but we need to allow
1045                 //   use of transactions on replicas for read snapshots. This is fine given
1046                 //   that transactions by themselves don't make changes, only actual writes
1047                 //   within the transaction matter, which we still detect.
1048                 return !preg_match(
1049                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1050                         $sql
1051                 );
1052         }
1053
1054         /**
1055          * @param string $sql
1056          * @return string|null
1057          */
1058         protected function getQueryVerb( $sql ) {
1059                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1060         }
1061
1062         /**
1063          * Determine whether a SQL statement is sensitive to isolation level.
1064          *
1065          * A SQL statement is considered transactable if its result could vary
1066          * depending on the transaction isolation level. Operational commands
1067          * such as 'SET' and 'SHOW' are not considered to be transactable.
1068          *
1069          * Main purpose: Used by query() to decide whether to begin a transaction
1070          * before the current query (in DBO_TRX mode, on by default).
1071          *
1072          * @param string $sql
1073          * @return bool
1074          */
1075         protected function isTransactableQuery( $sql ) {
1076                 return !in_array(
1077                         $this->getQueryVerb( $sql ),
1078                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
1079                         true
1080                 );
1081         }
1082
1083         /**
1084          * @param string $sql A SQL query
1085          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1086          * @return array A n-tuple of:
1087          *   - int|null: A self::TEMP_* constant for temp table operations or null otherwise
1088          *   - string|null: The name of the new temporary table $sql creates, or null
1089          *   - string|null: The name of the temporary table that $sql drops, or null
1090          */
1091         protected function getTempWrites( $sql, $pseudoPermanent ) {
1092                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1093
1094                 if ( preg_match(
1095                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1096                         $sql,
1097                         $matches
1098                 ) ) {
1099                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1100
1101                         return [ $type, $matches[1], null ];
1102                 } elseif ( preg_match(
1103                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1104                         $sql,
1105                         $matches
1106                 ) ) {
1107                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, $matches[1] ];
1108                 } elseif ( preg_match(
1109                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1110                         $sql,
1111                         $matches
1112                 ) ) {
1113                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1114                 } elseif ( preg_match(
1115                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1116                         $sql,
1117                         $matches
1118                 ) ) {
1119                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1120                 }
1121
1122                 return [ null, null, null ];
1123         }
1124
1125         /**
1126          * @param IResultWrapper|bool $ret
1127          * @param int|null $tmpType TEMP_NORMAL or TEMP_PSEUDO_PERMANENT
1128          * @param string|null $tmpNew Name of created temp table
1129          * @param string|null $tmpDel Name of dropped temp table
1130          */
1131         protected function registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel ) {
1132                 if ( $ret !== false ) {
1133                         if ( $tmpNew !== null ) {
1134                                 $this->sessionTempTables[$tmpNew] = $tmpType;
1135                         }
1136                         if ( $tmpDel !== null ) {
1137                                 unset( $this->sessionTempTables[$tmpDel] );
1138                         }
1139                 }
1140         }
1141
1142         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1143                 $flags = (int)$flags; // b/c; this field used to be a bool
1144                 // Sanity check that the SQL query is appropriate in the current context and is
1145                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1146                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1147
1148                 // Send the query to the server and fetch any corresponding errors
1149                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1150                 if ( $ret === false ) {
1151                         $ignoreErrors = $this->hasFlags( $flags, self::QUERY_SILENCE_ERRORS );
1152                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1153                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1154                 }
1155
1156                 return $this->resultObject( $ret );
1157         }
1158
1159         /**
1160          * Execute a query, retrying it if there is a recoverable connection loss
1161          *
1162          * This is similar to query() except:
1163          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1164          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1165          *   - It does not throw exceptions for common error cases
1166          *
1167          * This is meant for internal use with Database subclasses.
1168          *
1169          * @param string $sql Original SQL query
1170          * @param string $fname Name of the calling function
1171          * @param int $flags Bit field of class QUERY_* constants
1172          * @return array An n-tuple of:
1173          *   - mixed|bool: An object, resource, or true on success; false on failure
1174          *   - string: The result of calling lastError()
1175          *   - int: The result of calling lastErrno()
1176          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1177          * @throws DBUnexpectedError
1178          */
1179         final protected function executeQuery( $sql, $fname, $flags ) {
1180                 $this->assertHasConnectionHandle();
1181
1182                 $priorTransaction = $this->trxLevel();
1183
1184                 if ( $this->isWriteQuery( $sql ) ) {
1185                         // In theory, non-persistent writes are allowed in read-only mode, but due to things
1186                         // like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1187                         $this->assertIsWritableMaster();
1188                         // Do not treat temporary table writes as "meaningful writes" since they are only
1189                         // visible to one session and are not permanent. Profile them as reads. Integration
1190                         // tests can override this behavior via $flags.
1191                         $pseudoPermanent = $this->hasFlags( $flags, self::QUERY_PSEUDO_PERMANENT );
1192                         list( $tmpType, $tmpNew, $tmpDel ) = $this->getTempWrites( $sql, $pseudoPermanent );
1193                         $isPermWrite = ( $tmpType !== self::$TEMP_NORMAL );
1194                         // DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1195                         if ( $isPermWrite && $this->hasFlags( $flags, self::QUERY_REPLICA_ROLE ) ) {
1196                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1197                         }
1198                 } else {
1199                         // No permanent writes in this query
1200                         $isPermWrite = false;
1201                         // No temporary tables written to either
1202                         list( $tmpType, $tmpNew, $tmpDel ) = [ null, null, null ];
1203                 }
1204
1205                 // Add trace comment to the begin of the sql string, right after the operator.
1206                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1207                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1208
1209                 // Send the query to the server and fetch any corresponding errors.
1210                 // This also doubles as a "ping" to see if the connection was dropped.
1211                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1212                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1213
1214                 // Check if the query failed due to a recoverable connection loss
1215                 $allowRetry = !$this->hasFlags( $flags, self::QUERY_NO_RETRY );
1216                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1217                         // Silently resend the query to the server since it is safe and possible
1218                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1219                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1220                 }
1221
1222                 // Register creation and dropping of temporary tables
1223                 $this->registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel );
1224
1225                 $corruptedTrx = false;
1226
1227                 if ( $ret === false ) {
1228                         if ( $priorTransaction ) {
1229                                 if ( $recoverableSR ) {
1230                                         # We're ignoring an error that caused just the current query to be aborted.
1231                                         # But log the cause so we can log a deprecation notice if a caller actually
1232                                         # does ignore it.
1233                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1234                                 } elseif ( !$recoverableCL ) {
1235                                         # Either the query was aborted or all queries after BEGIN where aborted.
1236                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1237                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1238                                         # option is ROLLBACK, since the snapshots would have been released.
1239                                         $corruptedTrx = true; // cannot recover
1240                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1241                                         $this->trxStatusCause =
1242                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1243                                         $this->trxStatusIgnoredCause = null;
1244                                 }
1245                         }
1246                 }
1247
1248                 return [ $ret, $err, $errno, $corruptedTrx ];
1249         }
1250
1251         /**
1252          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1253          * tracking, and reconnects (without retry) on query failure due to connection loss
1254          *
1255          * @param string $sql Original SQL query
1256          * @param string $commentedSql SQL query with debugging/trace comment
1257          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1258          * @param string $fname Name of the calling function
1259          * @param int $flags Bit field of class QUERY_* constants
1260          * @return array An n-tuple of:
1261          *   - mixed|bool: An object, resource, or true on success; false on failure
1262          *   - string: The result of calling lastError()
1263          *   - int: The result of calling lastErrno()
1264          *       - bool: Whether a statement rollback error occured
1265          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1266          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1267          * @throws DBUnexpectedError
1268          */
1269         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1270                 $priorWritesPending = $this->writesOrCallbacksPending();
1271
1272                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1273                         $this->beginIfImplied( $sql, $fname );
1274                 }
1275
1276                 // Keep track of whether the transaction has write queries pending
1277                 if ( $isPermWrite ) {
1278                         $this->lastWriteTime = microtime( true );
1279                         if ( $this->trxLevel() && !$this->trxDoneWrites ) {
1280                                 $this->trxDoneWrites = true;
1281                                 $this->trxProfiler->transactionWritingIn(
1282                                         $this->server, $this->getDomainID(), $this->trxShortId );
1283                         }
1284                 }
1285
1286                 $prefix = !is_null( $this->getLBInfo( 'master' ) ) ? 'query-m: ' : 'query: ';
1287                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1288
1289                 $startTime = microtime( true );
1290                 $ps = $this->profiler
1291                         ? ( $this->profiler )( $generalizedSql->stringify() )
1292                         : null;
1293                 $this->affectedRowCount = null;
1294                 $this->lastQuery = $sql;
1295                 $ret = $this->doQuery( $commentedSql );
1296                 $lastError = $this->lastError();
1297                 $lastErrno = $this->lastErrno();
1298
1299                 $this->affectedRowCount = $this->affectedRows();
1300                 unset( $ps ); // profile out (if set)
1301                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1302
1303                 $recoverableSR = false; // recoverable statement rollback?
1304                 $recoverableCL = false; // recoverable connection loss?
1305                 $reconnected = false; // reconnection both attempted and succeeded?
1306
1307                 if ( $ret !== false ) {
1308                         $this->lastPing = $startTime;
1309                         if ( $isPermWrite && $this->trxLevel() ) {
1310                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1311                                 $this->trxWriteCallers[] = $fname;
1312                         }
1313                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1314                         # Check if no meaningful session state was lost
1315                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1316                         # Update session state tracking and try to restore the connection
1317                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1318                 } else {
1319                         # Check if only the last query was rolled back
1320                         $recoverableSR = $this->wasKnownStatementRollbackError();
1321                 }
1322
1323                 if ( $sql === self::$PING_QUERY ) {
1324                         $this->lastRoundTripEstimate = $queryRuntime;
1325                 }
1326
1327                 $this->trxProfiler->recordQueryCompletion(
1328                         $generalizedSql,
1329                         $startTime,
1330                         $isPermWrite,
1331                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1332                 );
1333
1334                 // Avoid the overhead of logging calls unless debug mode is enabled
1335                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1336                         $this->queryLogger->debug(
1337                                 "{method} [{runtime}s] {db_host}: $sql",
1338                                 [
1339                                         'method' => $fname,
1340                                         'db_host' => $this->getServer(),
1341                                         'domain' => $this->getDomainID(),
1342                                         'runtime' => round( $queryRuntime, 3 )
1343                                 ]
1344                         );
1345                 }
1346
1347                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1348         }
1349
1350         /**
1351          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1352          *
1353          * @param string $sql
1354          * @param string $fname
1355          */
1356         private function beginIfImplied( $sql, $fname ) {
1357                 if (
1358                         !$this->trxLevel() &&
1359                         $this->getFlag( self::DBO_TRX ) &&
1360                         $this->isTransactableQuery( $sql )
1361                 ) {
1362                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1363                         $this->trxAutomatic = true;
1364                 }
1365         }
1366
1367         /**
1368          * Update the estimated run-time of a query, not counting large row lock times
1369          *
1370          * LoadBalancer can be set to rollback transactions that will create huge replication
1371          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1372          * queries, like inserting a row can take a long time due to row locking. This method
1373          * uses some simple heuristics to discount those cases.
1374          *
1375          * @param string $sql A SQL write query
1376          * @param float $runtime Total runtime, including RTT
1377          * @param int $affected Affected row count
1378          */
1379         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1380                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1381                 $indicativeOfReplicaRuntime = true;
1382                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1383                         $verb = $this->getQueryVerb( $sql );
1384                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1385                         if ( $verb === 'INSERT' ) {
1386                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1387                         } elseif ( $verb === 'REPLACE' ) {
1388                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1389                         }
1390                 }
1391
1392                 $this->trxWriteDuration += $runtime;
1393                 $this->trxWriteQueryCount += 1;
1394                 $this->trxWriteAffectedRows += $affected;
1395                 if ( $indicativeOfReplicaRuntime ) {
1396                         $this->trxWriteAdjDuration += $runtime;
1397                         $this->trxWriteAdjQueryCount += 1;
1398                 }
1399         }
1400
1401         /**
1402          * Error out if the DB is not in a valid state for a query via query()
1403          *
1404          * @param string $sql
1405          * @param string $fname
1406          * @throws DBTransactionStateError
1407          */
1408         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1409                 $verb = $this->getQueryVerb( $sql );
1410                 if ( $verb === 'USE' ) {
1411                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead" );
1412                 }
1413
1414                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1415                         return;
1416                 }
1417
1418                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1419                         throw new DBTransactionStateError(
1420                                 $this,
1421                                 "Cannot execute query from $fname while transaction status is ERROR",
1422                                 [],
1423                                 $this->trxStatusCause
1424                         );
1425                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1426                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1427                         call_user_func( $this->deprecationLogger,
1428                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1429                                 "[$iLastErrno] $iLastError"
1430                         );
1431                         $this->trxStatusIgnoredCause = null;
1432                 }
1433         }
1434
1435         public function assertNoOpenTransactions() {
1436                 if ( $this->explicitTrxActive() ) {
1437                         throw new DBTransactionError(
1438                                 $this,
1439                                 "Explicit transaction still active. A caller may have caught an error. "
1440                                 . "Open transactions: " . $this->flatAtomicSectionList()
1441                         );
1442                 }
1443         }
1444
1445         /**
1446          * Determine whether it is safe to retry queries after a database connection is lost
1447          *
1448          * @param string $sql SQL query
1449          * @param bool $priorWritesPending Whether there is a transaction open with
1450          *     possible write queries or transaction pre-commit/idle callbacks
1451          *     waiting on it to finish.
1452          * @return bool True if it is safe to retry the query, false otherwise
1453          */
1454         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1455                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1456                 # Dropped connections also mean that named locks are automatically released.
1457                 # Only allow error suppression in autocommit mode or when the lost transaction
1458                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1459                 if ( $this->sessionNamedLocks ) {
1460                         return false; // possible critical section violation
1461                 } elseif ( $this->sessionTempTables ) {
1462                         return false; // tables might be queried latter
1463                 } elseif ( $sql === 'COMMIT' ) {
1464                         return !$priorWritesPending; // nothing written anyway? (T127428)
1465                 } elseif ( $sql === 'ROLLBACK' ) {
1466                         return true; // transaction lost...which is also what was requested :)
1467                 } elseif ( $this->explicitTrxActive() ) {
1468                         return false; // don't drop atomocity and explicit snapshots
1469                 } elseif ( $priorWritesPending ) {
1470                         return false; // prior writes lost from implicit transaction
1471                 }
1472
1473                 return true;
1474         }
1475
1476         /**
1477          * Clean things up after session (and thus transaction) loss before reconnect
1478          */
1479         private function handleSessionLossPreconnect() {
1480                 // Clean up tracking of session-level things...
1481                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1482                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1483                 $this->sessionTempTables = [];
1484                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1485                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1486                 $this->sessionNamedLocks = [];
1487                 // Session loss implies transaction loss
1488                 $oldTrxShortId = $this->consumeTrxShortId();
1489                 $this->trxAtomicCounter = 0;
1490                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1491                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1492                 // @note: leave trxRecurringCallbacks in place
1493                 if ( $this->trxDoneWrites ) {
1494                         $this->trxProfiler->transactionWritingOut(
1495                                 $this->server,
1496                                 $this->getDomainID(),
1497                                 $oldTrxShortId,
1498                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1499                                 $this->trxWriteAffectedRows
1500                         );
1501                 }
1502         }
1503
1504         /**
1505          * Clean things up after session (and thus transaction) loss after reconnect
1506          */
1507         private function handleSessionLossPostconnect() {
1508                 try {
1509                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1510                         // If callback suppression is set then the array will remain unhandled.
1511                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1512                 } catch ( Exception $ex ) {
1513                         // Already logged; move on...
1514                 }
1515                 try {
1516                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1517                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1518                 } catch ( Exception $ex ) {
1519                         // Already logged; move on...
1520                 }
1521         }
1522
1523         /**
1524          * Reset the transaction ID and return the old one
1525          *
1526          * @return string The old transaction ID or the empty string if there wasn't one
1527          */
1528         private function consumeTrxShortId() {
1529                 $old = $this->trxShortId;
1530                 $this->trxShortId = '';
1531
1532                 return $old;
1533         }
1534
1535         /**
1536          * Checks whether the cause of the error is detected to be a timeout.
1537          *
1538          * It returns false by default, and not all engines support detecting this yet.
1539          * If this returns false, it will be treated as a generic query error.
1540          *
1541          * @param string $error Error text
1542          * @param int $errno Error number
1543          * @return bool
1544          */
1545         protected function wasQueryTimeout( $error, $errno ) {
1546                 return false;
1547         }
1548
1549         /**
1550          * Report a query error. Log the error, and if neither the object ignore
1551          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1552          *
1553          * @param string $error
1554          * @param int $errno
1555          * @param string $sql
1556          * @param string $fname
1557          * @param bool $ignore
1558          * @throws DBQueryError
1559          */
1560         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1561                 if ( $ignore ) {
1562                         $this->queryLogger->debug( "SQL ERROR (ignored): $error" );
1563                 } else {
1564                         throw $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1565                 }
1566         }
1567
1568         /**
1569          * @param string $error
1570          * @param string|int $errno
1571          * @param string $sql
1572          * @param string $fname
1573          * @return DBError
1574          */
1575         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1576                 $this->queryLogger->error(
1577                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1578                         $this->getLogContext( [
1579                                 'method' => __METHOD__,
1580                                 'errno' => $errno,
1581                                 'error' => $error,
1582                                 'sql1line' => mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 ),
1583                                 'fname' => $fname,
1584                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1585                         ] )
1586                 );
1587
1588                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1589                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1590                 } elseif ( $this->wasConnectionError( $errno ) ) {
1591                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1592                 } else {
1593                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1594                 }
1595
1596                 return $e;
1597         }
1598
1599         /**
1600          * @param string $error
1601          * @return DBConnectionError
1602          */
1603         final protected function newExceptionAfterConnectError( $error ) {
1604                 // Connection was not fully initialized and is not safe for use
1605                 $this->conn = null;
1606
1607                 $this->connLogger->error(
1608                         "Error connecting to {db_server} as user {db_user}: {error}",
1609                         $this->getLogContext( [
1610                                 'error' => $error,
1611                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1612                         ] )
1613                 );
1614
1615                 return new DBConnectionError( $this, $error );
1616         }
1617
1618         public function freeResult( $res ) {
1619         }
1620
1621         public function selectField(
1622                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1623         ) {
1624                 if ( $var === '*' ) { // sanity
1625                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1626                 }
1627
1628                 if ( !is_array( $options ) ) {
1629                         $options = [ $options ];
1630                 }
1631
1632                 $options['LIMIT'] = 1;
1633
1634                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1635                 if ( $res === false ) {
1636                         throw new DBUnexpectedError( $this, "Got false from select()" );
1637                 }
1638
1639                 $row = $this->fetchRow( $res );
1640                 if ( $row === false ) {
1641                         return false;
1642                 }
1643
1644                 return reset( $row );
1645         }
1646
1647         public function selectFieldValues(
1648                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1649         ) {
1650                 if ( $var === '*' ) { // sanity
1651                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1652                 } elseif ( !is_string( $var ) ) { // sanity
1653                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1654                 }
1655
1656                 if ( !is_array( $options ) ) {
1657                         $options = [ $options ];
1658                 }
1659
1660                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1661                 if ( $res === false ) {
1662                         throw new DBUnexpectedError( $this, "Got false from select()" );
1663                 }
1664
1665                 $values = [];
1666                 foreach ( $res as $row ) {
1667                         $values[] = $row->value;
1668                 }
1669
1670                 return $values;
1671         }
1672
1673         /**
1674          * Returns an optional USE INDEX clause to go after the table, and a
1675          * string to go at the end of the query.
1676          *
1677          * @param array $options Associative array of options to be turned into
1678          *   an SQL query, valid keys are listed in the function.
1679          * @return array
1680          * @see Database::select()
1681          */
1682         protected function makeSelectOptions( $options ) {
1683                 $preLimitTail = $postLimitTail = '';
1684                 $startOpts = '';
1685
1686                 $noKeyOptions = [];
1687
1688                 foreach ( $options as $key => $option ) {
1689                         if ( is_numeric( $key ) ) {
1690                                 $noKeyOptions[$option] = true;
1691                         }
1692                 }
1693
1694                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1695
1696                 $preLimitTail .= $this->makeOrderBy( $options );
1697
1698                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1699                         $postLimitTail .= ' FOR UPDATE';
1700                 }
1701
1702                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1703                         $postLimitTail .= ' LOCK IN SHARE MODE';
1704                 }
1705
1706                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1707                         $startOpts .= 'DISTINCT';
1708                 }
1709
1710                 # Various MySQL extensions
1711                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1712                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1713                 }
1714
1715                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1716                         $startOpts .= ' SQL_BIG_RESULT';
1717                 }
1718
1719                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1720                         $startOpts .= ' SQL_BUFFER_RESULT';
1721                 }
1722
1723                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1724                         $startOpts .= ' SQL_SMALL_RESULT';
1725                 }
1726
1727                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1728                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1729                 }
1730
1731                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1732                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1733                 } else {
1734                         $useIndex = '';
1735                 }
1736                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1737                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1738                 } else {
1739                         $ignoreIndex = '';
1740                 }
1741
1742                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1743         }
1744
1745         /**
1746          * Returns an optional GROUP BY with an optional HAVING
1747          *
1748          * @param array $options Associative array of options
1749          * @return string
1750          * @see Database::select()
1751          * @since 1.21
1752          */
1753         protected function makeGroupByWithHaving( $options ) {
1754                 $sql = '';
1755                 if ( isset( $options['GROUP BY'] ) ) {
1756                         $gb = is_array( $options['GROUP BY'] )
1757                                 ? implode( ',', $options['GROUP BY'] )
1758                                 : $options['GROUP BY'];
1759                         $sql .= ' GROUP BY ' . $gb;
1760                 }
1761                 if ( isset( $options['HAVING'] ) ) {
1762                         $having = is_array( $options['HAVING'] )
1763                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1764                                 : $options['HAVING'];
1765                         $sql .= ' HAVING ' . $having;
1766                 }
1767
1768                 return $sql;
1769         }
1770
1771         /**
1772          * Returns an optional ORDER BY
1773          *
1774          * @param array $options Associative array of options
1775          * @return string
1776          * @see Database::select()
1777          * @since 1.21
1778          */
1779         protected function makeOrderBy( $options ) {
1780                 if ( isset( $options['ORDER BY'] ) ) {
1781                         $ob = is_array( $options['ORDER BY'] )
1782                                 ? implode( ',', $options['ORDER BY'] )
1783                                 : $options['ORDER BY'];
1784
1785                         return ' ORDER BY ' . $ob;
1786                 }
1787
1788                 return '';
1789         }
1790
1791         public function select(
1792                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1793         ) {
1794                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1795
1796                 return $this->query( $sql, $fname );
1797         }
1798
1799         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1800                 $options = [], $join_conds = []
1801         ) {
1802                 if ( is_array( $vars ) ) {
1803                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1804                 } else {
1805                         $fields = $vars;
1806                 }
1807
1808                 $options = (array)$options;
1809                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1810                         ? $options['USE INDEX']
1811                         : [];
1812                 $ignoreIndexes = (
1813                         isset( $options['IGNORE INDEX'] ) &&
1814                         is_array( $options['IGNORE INDEX'] )
1815                 )
1816                         ? $options['IGNORE INDEX']
1817                         : [];
1818
1819                 if (
1820                         $this->selectOptionsIncludeLocking( $options ) &&
1821                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1822                 ) {
1823                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1824                         // functions. Discourage use of such queries to encourage compatibility.
1825                         call_user_func(
1826                                 $this->deprecationLogger,
1827                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)"
1828                         );
1829                 }
1830
1831                 if ( is_array( $table ) ) {
1832                         $from = ' FROM ' .
1833                                 $this->tableNamesWithIndexClauseOrJOIN(
1834                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1835                 } elseif ( $table != '' ) {
1836                         $from = ' FROM ' .
1837                                 $this->tableNamesWithIndexClauseOrJOIN(
1838                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1839                 } else {
1840                         $from = '';
1841                 }
1842
1843                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1844                         $this->makeSelectOptions( $options );
1845
1846                 if ( is_array( $conds ) ) {
1847                         $conds = $this->makeList( $conds, self::LIST_AND );
1848                 }
1849
1850                 if ( $conds === null || $conds === false ) {
1851                         $this->queryLogger->warning(
1852                                 __METHOD__
1853                                 . ' called from '
1854                                 . $fname
1855                                 . ' with incorrect parameters: $conds must be a string or an array'
1856                         );
1857                         $conds = '';
1858                 }
1859
1860                 if ( $conds === '' || $conds === '*' ) {
1861                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1862                 } elseif ( is_string( $conds ) ) {
1863                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1864                                 "WHERE $conds $preLimitTail";
1865                 } else {
1866                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1867                 }
1868
1869                 if ( isset( $options['LIMIT'] ) ) {
1870                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1871                                 $options['OFFSET'] ?? false );
1872                 }
1873                 $sql = "$sql $postLimitTail";
1874
1875                 if ( isset( $options['EXPLAIN'] ) ) {
1876                         $sql = 'EXPLAIN ' . $sql;
1877                 }
1878
1879                 return $sql;
1880         }
1881
1882         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1883                 $options = [], $join_conds = []
1884         ) {
1885                 $options = (array)$options;
1886                 $options['LIMIT'] = 1;
1887
1888                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1889                 if ( $res === false ) {
1890                         throw new DBUnexpectedError( $this, "Got false from select()" );
1891                 }
1892
1893                 if ( !$this->numRows( $res ) ) {
1894                         return false;
1895                 }
1896
1897                 return $this->fetchObject( $res );
1898         }
1899
1900         public function estimateRowCount(
1901                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1902         ) {
1903                 $conds = $this->normalizeConditions( $conds, $fname );
1904                 $column = $this->extractSingleFieldFromList( $var );
1905                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1906                         $conds[] = "$column IS NOT NULL";
1907                 }
1908
1909                 $res = $this->select(
1910                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1911                 );
1912                 $row = $res ? $this->fetchRow( $res ) : [];
1913
1914                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1915         }
1916
1917         public function selectRowCount(
1918                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1919         ) {
1920                 $conds = $this->normalizeConditions( $conds, $fname );
1921                 $column = $this->extractSingleFieldFromList( $var );
1922                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1923                         $conds[] = "$column IS NOT NULL";
1924                 }
1925
1926                 $res = $this->select(
1927                         [
1928                                 'tmp_count' => $this->buildSelectSubquery(
1929                                         $tables,
1930                                         '1',
1931                                         $conds,
1932                                         $fname,
1933                                         $options,
1934                                         $join_conds
1935                                 )
1936                         ],
1937                         [ 'rowcount' => 'COUNT(*)' ],
1938                         [],
1939                         $fname
1940                 );
1941                 $row = $res ? $this->fetchRow( $res ) : [];
1942
1943                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1944         }
1945
1946         /**
1947          * @param string|array $options
1948          * @return bool
1949          */
1950         private function selectOptionsIncludeLocking( $options ) {
1951                 $options = (array)$options;
1952                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1953                         if ( in_array( $lock, $options, true ) ) {
1954                                 return true;
1955                         }
1956                 }
1957
1958                 return false;
1959         }
1960
1961         /**
1962          * @param array|string $fields
1963          * @param array|string $options
1964          * @return bool
1965          */
1966         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1967                 foreach ( (array)$options as $key => $value ) {
1968                         if ( is_string( $key ) ) {
1969                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1970                                         return true;
1971                                 }
1972                         } elseif ( is_string( $value ) ) {
1973                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1974                                         return true;
1975                                 }
1976                         }
1977                 }
1978
1979                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1980                 foreach ( (array)$fields as $field ) {
1981                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1982                                 return true;
1983                         }
1984                 }
1985
1986                 return false;
1987         }
1988
1989         /**
1990          * @param array|string $conds
1991          * @param string $fname
1992          * @return array
1993          */
1994         final protected function normalizeConditions( $conds, $fname ) {
1995                 if ( $conds === null || $conds === false ) {
1996                         $this->queryLogger->warning(
1997                                 __METHOD__
1998                                 . ' called from '
1999                                 . $fname
2000                                 . ' with incorrect parameters: $conds must be a string or an array'
2001                         );
2002                         $conds = '';
2003                 }
2004
2005                 if ( !is_array( $conds ) ) {
2006                         $conds = ( $conds === '' ) ? [] : [ $conds ];
2007                 }
2008
2009                 return $conds;
2010         }
2011
2012         /**
2013          * @param array|string $var Field parameter in the style of select()
2014          * @return string|null Column name or null; ignores aliases
2015          * @throws DBUnexpectedError Errors out if multiple columns are given
2016          */
2017         final protected function extractSingleFieldFromList( $var ) {
2018                 if ( is_array( $var ) ) {
2019                         if ( !$var ) {
2020                                 $column = null;
2021                         } elseif ( count( $var ) == 1 ) {
2022                                 $column = $var[0] ?? reset( $var );
2023                         } else {
2024                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns' );
2025                         }
2026                 } else {
2027                         $column = $var;
2028                 }
2029
2030                 return $column;
2031         }
2032
2033         public function lockForUpdate(
2034                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
2035         ) {
2036                 if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
2037                         throw new DBUnexpectedError(
2038                                 $this,
2039                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
2040                         );
2041                 }
2042
2043                 $options = (array)$options;
2044                 $options[] = 'FOR UPDATE';
2045
2046                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2047         }
2048
2049         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2050                 $info = $this->fieldInfo( $table, $field );
2051
2052                 return (bool)$info;
2053         }
2054
2055         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2056                 if ( !$this->tableExists( $table ) ) {
2057                         return null;
2058                 }
2059
2060                 $info = $this->indexInfo( $table, $index, $fname );
2061                 if ( is_null( $info ) ) {
2062                         return null;
2063                 } else {
2064                         return $info !== false;
2065                 }
2066         }
2067
2068         abstract public function tableExists( $table, $fname = __METHOD__ );
2069
2070         public function indexUnique( $table, $index ) {
2071                 $indexInfo = $this->indexInfo( $table, $index );
2072
2073                 if ( !$indexInfo ) {
2074                         return null;
2075                 }
2076
2077                 return !$indexInfo[0]->Non_unique;
2078         }
2079
2080         /**
2081          * Helper for Database::insert().
2082          *
2083          * @param array $options
2084          * @return string
2085          */
2086         protected function makeInsertOptions( $options ) {
2087                 return implode( ' ', $options );
2088         }
2089
2090         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2091                 # No rows to insert, easy just return now
2092                 if ( !count( $a ) ) {
2093                         return true;
2094                 }
2095
2096                 $table = $this->tableName( $table );
2097
2098                 if ( !is_array( $options ) ) {
2099                         $options = [ $options ];
2100                 }
2101
2102                 $options = $this->makeInsertOptions( $options );
2103
2104                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2105                         $multi = true;
2106                         $keys = array_keys( $a[0] );
2107                 } else {
2108                         $multi = false;
2109                         $keys = array_keys( $a );
2110                 }
2111
2112                 $sql = 'INSERT ' . $options .
2113                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2114
2115                 if ( $multi ) {
2116                         $first = true;
2117                         foreach ( $a as $row ) {
2118                                 if ( $first ) {
2119                                         $first = false;
2120                                 } else {
2121                                         $sql .= ',';
2122                                 }
2123                                 $sql .= '(' . $this->makeList( $row ) . ')';
2124                         }
2125                 } else {
2126                         $sql .= '(' . $this->makeList( $a ) . ')';
2127                 }
2128
2129                 $this->query( $sql, $fname );
2130
2131                 return true;
2132         }
2133
2134         /**
2135          * Make UPDATE options array for Database::makeUpdateOptions
2136          *
2137          * @param array $options
2138          * @return array
2139          */
2140         protected function makeUpdateOptionsArray( $options ) {
2141                 if ( !is_array( $options ) ) {
2142                         $options = [ $options ];
2143                 }
2144
2145                 $opts = [];
2146
2147                 if ( in_array( 'IGNORE', $options ) ) {
2148                         $opts[] = 'IGNORE';
2149                 }
2150
2151                 return $opts;
2152         }
2153
2154         /**
2155          * Make UPDATE options for the Database::update function
2156          *
2157          * @param array $options The options passed to Database::update
2158          * @return string
2159          */
2160         protected function makeUpdateOptions( $options ) {
2161                 $opts = $this->makeUpdateOptionsArray( $options );
2162
2163                 return implode( ' ', $opts );
2164         }
2165
2166         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2167                 $table = $this->tableName( $table );
2168                 $opts = $this->makeUpdateOptions( $options );
2169                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2170
2171                 if ( $conds !== [] && $conds !== '*' ) {
2172                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2173                 }
2174
2175                 $this->query( $sql, $fname );
2176
2177                 return true;
2178         }
2179
2180         public function makeList( $a, $mode = self::LIST_COMMA ) {
2181                 if ( !is_array( $a ) ) {
2182                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2183                 }
2184
2185                 $first = true;
2186                 $list = '';
2187
2188                 foreach ( $a as $field => $value ) {
2189                         if ( !$first ) {
2190                                 if ( $mode == self::LIST_AND ) {
2191                                         $list .= ' AND ';
2192                                 } elseif ( $mode == self::LIST_OR ) {
2193                                         $list .= ' OR ';
2194                                 } else {
2195                                         $list .= ',';
2196                                 }
2197                         } else {
2198                                 $first = false;
2199                         }
2200
2201                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2202                                 $list .= "($value)";
2203                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2204                                 $list .= "$value";
2205                         } elseif (
2206                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2207                         ) {
2208                                 // Remove null from array to be handled separately if found
2209                                 $includeNull = false;
2210                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2211                                         $includeNull = true;
2212                                         unset( $value[$nullKey] );
2213                                 }
2214                                 if ( count( $value ) == 0 && !$includeNull ) {
2215                                         throw new InvalidArgumentException(
2216                                                 __METHOD__ . ": empty input for field $field" );
2217                                 } elseif ( count( $value ) == 0 ) {
2218                                         // only check if $field is null
2219                                         $list .= "$field IS NULL";
2220                                 } else {
2221                                         // IN clause contains at least one valid element
2222                                         if ( $includeNull ) {
2223                                                 // Group subconditions to ensure correct precedence
2224                                                 $list .= '(';
2225                                         }
2226                                         if ( count( $value ) == 1 ) {
2227                                                 // Special-case single values, as IN isn't terribly efficient
2228                                                 // Don't necessarily assume the single key is 0; we don't
2229                                                 // enforce linear numeric ordering on other arrays here.
2230                                                 $value = array_values( $value )[0];
2231                                                 $list .= $field . " = " . $this->addQuotes( $value );
2232                                         } else {
2233                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2234                                         }
2235                                         // if null present in array, append IS NULL
2236                                         if ( $includeNull ) {
2237                                                 $list .= " OR $field IS NULL)";
2238                                         }
2239                                 }
2240                         } elseif ( $value === null ) {
2241                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2242                                         $list .= "$field IS ";
2243                                 } elseif ( $mode == self::LIST_SET ) {
2244                                         $list .= "$field = ";
2245                                 }
2246                                 $list .= 'NULL';
2247                         } else {
2248                                 if (
2249                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2250                                 ) {
2251                                         $list .= "$field = ";
2252                                 }
2253                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2254                         }
2255                 }
2256
2257                 return $list;
2258         }
2259
2260         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2261                 $conds = [];
2262
2263                 foreach ( $data as $base => $sub ) {
2264                         if ( count( $sub ) ) {
2265                                 $conds[] = $this->makeList(
2266                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2267                                         self::LIST_AND );
2268                         }
2269                 }
2270
2271                 if ( $conds ) {
2272                         return $this->makeList( $conds, self::LIST_OR );
2273                 } else {
2274                         // Nothing to search for...
2275                         return false;
2276                 }
2277         }
2278
2279         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2280                 return $valuename;
2281         }
2282
2283         public function bitNot( $field ) {
2284                 return "(~$field)";
2285         }
2286
2287         public function bitAnd( $fieldLeft, $fieldRight ) {
2288                 return "($fieldLeft & $fieldRight)";
2289         }
2290
2291         public function bitOr( $fieldLeft, $fieldRight ) {
2292                 return "($fieldLeft | $fieldRight)";
2293         }
2294
2295         public function buildConcat( $stringList ) {
2296                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2297         }
2298
2299         public function buildGroupConcatField(
2300                 $delim, $table, $field, $conds = '', $join_conds = []
2301         ) {
2302                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2303
2304                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2305         }
2306
2307         public function buildSubstring( $input, $startPosition, $length = null ) {
2308                 $this->assertBuildSubstringParams( $startPosition, $length );
2309                 $functionBody = "$input FROM $startPosition";
2310                 if ( $length !== null ) {
2311                         $functionBody .= " FOR $length";
2312                 }
2313                 return 'SUBSTRING(' . $functionBody . ')';
2314         }
2315
2316         /**
2317          * Check type and bounds for parameters to self::buildSubstring()
2318          *
2319          * All supported databases have substring functions that behave the same for
2320          * positive $startPosition and non-negative $length, but behaviors differ when
2321          * given 0 or negative $startPosition or negative $length. The simplest
2322          * solution to that is to just forbid those values.
2323          *
2324          * @param int $startPosition
2325          * @param int|null $length
2326          * @since 1.31
2327          */
2328         protected function assertBuildSubstringParams( $startPosition, $length ) {
2329                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2330                         throw new InvalidArgumentException(
2331                                 '$startPosition must be a positive integer'
2332                         );
2333                 }
2334                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2335                         throw new InvalidArgumentException(
2336                                 '$length must be null or an integer greater than or equal to 0'
2337                         );
2338                 }
2339         }
2340
2341         public function buildStringCast( $field ) {
2342                 // In theory this should work for any standards-compliant
2343                 // SQL implementation, although it may not be the best way to do it.
2344                 return "CAST( $field AS CHARACTER )";
2345         }
2346
2347         public function buildIntegerCast( $field ) {
2348                 return 'CAST( ' . $field . ' AS INTEGER )';
2349         }
2350
2351         public function buildSelectSubquery(
2352                 $table, $vars, $conds = '', $fname = __METHOD__,
2353                 $options = [], $join_conds = []
2354         ) {
2355                 return new Subquery(
2356                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2357                 );
2358         }
2359
2360         public function databasesAreIndependent() {
2361                 return false;
2362         }
2363
2364         final public function selectDB( $db ) {
2365                 $this->selectDomain( new DatabaseDomain(
2366                         $db,
2367                         $this->currentDomain->getSchema(),
2368                         $this->currentDomain->getTablePrefix()
2369                 ) );
2370
2371                 return true;
2372         }
2373
2374         final public function selectDomain( $domain ) {
2375                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2376         }
2377
2378         /**
2379          * @param DatabaseDomain $domain
2380          * @throws DBConnectionError
2381          * @throws DBError
2382          * @since 1.32
2383          */
2384         protected function doSelectDomain( DatabaseDomain $domain ) {
2385                 $this->currentDomain = $domain;
2386         }
2387
2388         public function getDBname() {
2389                 return $this->currentDomain->getDatabase();
2390         }
2391
2392         public function getServer() {
2393                 return $this->server;
2394         }
2395
2396         public function tableName( $name, $format = 'quoted' ) {
2397                 if ( $name instanceof Subquery ) {
2398                         throw new DBUnexpectedError(
2399                                 $this,
2400                                 __METHOD__ . ': got Subquery instance when expecting a string'
2401                         );
2402                 }
2403
2404                 # Skip the entire process when we have a string quoted on both ends.
2405                 # Note that we check the end so that we will still quote any use of
2406                 # use of `database`.table. But won't break things if someone wants
2407                 # to query a database table with a dot in the name.
2408                 if ( $this->isQuotedIdentifier( $name ) ) {
2409                         return $name;
2410                 }
2411
2412                 # Lets test for any bits of text that should never show up in a table
2413                 # name. Basically anything like JOIN or ON which are actually part of
2414                 # SQL queries, but may end up inside of the table value to combine
2415                 # sql. Such as how the API is doing.
2416                 # Note that we use a whitespace test rather than a \b test to avoid
2417                 # any remote case where a word like on may be inside of a table name
2418                 # surrounded by symbols which may be considered word breaks.
2419                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2420                         $this->queryLogger->warning(
2421                                 __METHOD__ . ": use of subqueries is not supported this way",
2422                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2423                         );
2424
2425                         return $name;
2426                 }
2427
2428                 # Split database and table into proper variables.
2429                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2430
2431                 # Quote $table and apply the prefix if not quoted.
2432                 # $tableName might be empty if this is called from Database::replaceVars()
2433                 $tableName = "{$prefix}{$table}";
2434                 if ( $format === 'quoted'
2435                         && !$this->isQuotedIdentifier( $tableName )
2436                         && $tableName !== ''
2437                 ) {
2438                         $tableName = $this->addIdentifierQuotes( $tableName );
2439                 }
2440
2441                 # Quote $schema and $database and merge them with the table name if needed
2442                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2443                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2444
2445                 return $tableName;
2446         }
2447
2448         /**
2449          * Get the table components needed for a query given the currently selected database
2450          *
2451          * @param string $name Table name in the form of db.schema.table, db.table, or table
2452          * @return array (DB name or "" for default, schema name, table prefix, table name)
2453          */
2454         protected function qualifiedTableComponents( $name ) {
2455                 # We reverse the explode so that database.table and table both output the correct table.
2456                 $dbDetails = explode( '.', $name, 3 );
2457                 if ( count( $dbDetails ) == 3 ) {
2458                         list( $database, $schema, $table ) = $dbDetails;
2459                         # We don't want any prefix added in this case
2460                         $prefix = '';
2461                 } elseif ( count( $dbDetails ) == 2 ) {
2462                         list( $database, $table ) = $dbDetails;
2463                         # We don't want any prefix added in this case
2464                         $prefix = '';
2465                         # In dbs that support it, $database may actually be the schema
2466                         # but that doesn't affect any of the functionality here
2467                         $schema = '';
2468                 } else {
2469                         list( $table ) = $dbDetails;
2470                         if ( isset( $this->tableAliases[$table] ) ) {
2471                                 $database = $this->tableAliases[$table]['dbname'];
2472                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2473                                         ? $this->tableAliases[$table]['schema']
2474                                         : $this->relationSchemaQualifier();
2475                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2476                                         ? $this->tableAliases[$table]['prefix']
2477                                         : $this->tablePrefix();
2478                         } else {
2479                                 $database = '';
2480                                 $schema = $this->relationSchemaQualifier(); # Default schema
2481                                 $prefix = $this->tablePrefix(); # Default prefix
2482                         }
2483                 }
2484
2485                 return [ $database, $schema, $prefix, $table ];
2486         }
2487
2488         /**
2489          * @param string|null $namespace Database or schema
2490          * @param string $relation Name of table, view, sequence, etc...
2491          * @param string $format One of (raw, quoted)
2492          * @return string Relation name with quoted and merged $namespace as needed
2493          */
2494         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2495                 if ( strlen( $namespace ) ) {
2496                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2497                                 $namespace = $this->addIdentifierQuotes( $namespace );
2498                         }
2499                         $relation = $namespace . '.' . $relation;
2500                 }
2501
2502                 return $relation;
2503         }
2504
2505         public function tableNames() {
2506                 $inArray = func_get_args();
2507                 $retVal = [];
2508
2509                 foreach ( $inArray as $name ) {
2510                         $retVal[$name] = $this->tableName( $name );
2511                 }
2512
2513                 return $retVal;
2514         }
2515
2516         public function tableNamesN() {
2517                 $inArray = func_get_args();
2518                 $retVal = [];
2519
2520                 foreach ( $inArray as $name ) {
2521                         $retVal[] = $this->tableName( $name );
2522                 }
2523
2524                 return $retVal;
2525         }
2526
2527         /**
2528          * Get an aliased table name
2529          *
2530          * This returns strings like "tableName AS newTableName" for aliased tables
2531          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2532          *
2533          * @see Database::tableName()
2534          * @param string|Subquery $table Table name or object with a 'sql' field
2535          * @param string|bool $alias Table alias (optional)
2536          * @return string SQL name for aliased table. Will not alias a table to its own name
2537          */
2538         protected function tableNameWithAlias( $table, $alias = false ) {
2539                 if ( is_string( $table ) ) {
2540                         $quotedTable = $this->tableName( $table );
2541                 } elseif ( $table instanceof Subquery ) {
2542                         $quotedTable = (string)$table;
2543                 } else {
2544                         throw new InvalidArgumentException( "Table must be a string or Subquery" );
2545                 }
2546
2547                 if ( $alias === false || $alias === $table ) {
2548                         if ( $table instanceof Subquery ) {
2549                                 throw new InvalidArgumentException( "Subquery table missing alias" );
2550                         }
2551
2552                         return $quotedTable;
2553                 } else {
2554                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2555                 }
2556         }
2557
2558         /**
2559          * Gets an array of aliased table names
2560          *
2561          * @param array $tables [ [alias] => table ]
2562          * @return string[] See tableNameWithAlias()
2563          */
2564         protected function tableNamesWithAlias( $tables ) {
2565                 $retval = [];
2566                 foreach ( $tables as $alias => $table ) {
2567                         if ( is_numeric( $alias ) ) {
2568                                 $alias = $table;
2569                         }
2570                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2571                 }
2572
2573                 return $retval;
2574         }
2575
2576         /**
2577          * Get an aliased field name
2578          * e.g. fieldName AS newFieldName
2579          *
2580          * @param string $name Field name
2581          * @param string|bool $alias Alias (optional)
2582          * @return string SQL name for aliased field. Will not alias a field to its own name
2583          */
2584         protected function fieldNameWithAlias( $name, $alias = false ) {
2585                 if ( !$alias || (string)$alias === (string)$name ) {
2586                         return $name;
2587                 } else {
2588                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2589                 }
2590         }
2591
2592         /**
2593          * Gets an array of aliased field names
2594          *
2595          * @param array $fields [ [alias] => field ]
2596          * @return string[] See fieldNameWithAlias()
2597          */
2598         protected function fieldNamesWithAlias( $fields ) {
2599                 $retval = [];
2600                 foreach ( $fields as $alias => $field ) {
2601                         if ( is_numeric( $alias ) ) {
2602                                 $alias = $field;
2603                         }
2604                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2605                 }
2606
2607                 return $retval;
2608         }
2609
2610         /**
2611          * Get the aliased table name clause for a FROM clause
2612          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2613          *
2614          * @param array $tables ( [alias] => table )
2615          * @param array $use_index Same as for select()
2616          * @param array $ignore_index Same as for select()
2617          * @param array $join_conds Same as for select()
2618          * @return string
2619          */
2620         protected function tableNamesWithIndexClauseOrJOIN(
2621                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2622         ) {
2623                 $ret = [];
2624                 $retJOIN = [];
2625                 $use_index = (array)$use_index;
2626                 $ignore_index = (array)$ignore_index;
2627                 $join_conds = (array)$join_conds;
2628
2629                 foreach ( $tables as $alias => $table ) {
2630                         if ( !is_string( $alias ) ) {
2631                                 // No alias? Set it equal to the table name
2632                                 $alias = $table;
2633                         }
2634
2635                         if ( is_array( $table ) ) {
2636                                 // A parenthesized group
2637                                 if ( count( $table ) > 1 ) {
2638                                         $joinedTable = '(' .
2639                                                 $this->tableNamesWithIndexClauseOrJOIN(
2640                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2641                                 } else {
2642                                         // Degenerate case
2643                                         $innerTable = reset( $table );
2644                                         $innerAlias = key( $table );
2645                                         $joinedTable = $this->tableNameWithAlias(
2646                                                 $innerTable,
2647                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2648                                         );
2649                                 }
2650                         } else {
2651                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2652                         }
2653
2654                         // Is there a JOIN clause for this table?
2655                         if ( isset( $join_conds[$alias] ) ) {
2656                                 list( $joinType, $conds ) = $join_conds[$alias];
2657                                 $tableClause = $joinType;
2658                                 $tableClause .= ' ' . $joinedTable;
2659                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2660                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2661                                         if ( $use != '' ) {
2662                                                 $tableClause .= ' ' . $use;
2663                                         }
2664                                 }
2665                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2666                                         $ignore = $this->ignoreIndexClause(
2667                                                 implode( ',', (array)$ignore_index[$alias] ) );
2668                                         if ( $ignore != '' ) {
2669                                                 $tableClause .= ' ' . $ignore;
2670                                         }
2671                                 }
2672                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2673                                 if ( $on != '' ) {
2674                                         $tableClause .= ' ON (' . $on . ')';
2675                                 }
2676
2677                                 $retJOIN[] = $tableClause;
2678                         } elseif ( isset( $use_index[$alias] ) ) {
2679                                 // Is there an INDEX clause for this table?
2680                                 $tableClause = $joinedTable;
2681                                 $tableClause .= ' ' . $this->useIndexClause(
2682                                                 implode( ',', (array)$use_index[$alias] )
2683                                         );
2684
2685                                 $ret[] = $tableClause;
2686                         } elseif ( isset( $ignore_index[$alias] ) ) {
2687                                 // Is there an INDEX clause for this table?
2688                                 $tableClause = $joinedTable;
2689                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2690                                                 implode( ',', (array)$ignore_index[$alias] )
2691                                         );
2692
2693                                 $ret[] = $tableClause;
2694                         } else {
2695                                 $tableClause = $joinedTable;
2696
2697                                 $ret[] = $tableClause;
2698                         }
2699                 }
2700
2701                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2702                 $implicitJoins = implode( ',', $ret );
2703                 $explicitJoins = implode( ' ', $retJOIN );
2704
2705                 // Compile our final table clause
2706                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2707         }
2708
2709         /**
2710          * Allows for index remapping in queries where this is not consistent across DBMS
2711          *
2712          * @param string $index
2713          * @return string
2714          */
2715         protected function indexName( $index ) {
2716                 return $this->indexAliases[$index] ?? $index;
2717         }
2718
2719         public function addQuotes( $s ) {
2720                 if ( $s instanceof Blob ) {
2721                         $s = $s->fetch();
2722                 }
2723                 if ( $s === null ) {
2724                         return 'NULL';
2725                 } elseif ( is_bool( $s ) ) {
2726                         return (int)$s;
2727                 } else {
2728                         # This will also quote numeric values. This should be harmless,
2729                         # and protects against weird problems that occur when they really
2730                         # _are_ strings such as article titles and string->number->string
2731                         # conversion is not 1:1.
2732                         return "'" . $this->strencode( $s ) . "'";
2733                 }
2734         }
2735
2736         public function addIdentifierQuotes( $s ) {
2737                 return '"' . str_replace( '"', '""', $s ) . '"';
2738         }
2739
2740         /**
2741          * Returns if the given identifier looks quoted or not according to
2742          * the database convention for quoting identifiers .
2743          *
2744          * @note Do not use this to determine if untrusted input is safe.
2745          *   A malicious user can trick this function.
2746          * @param string $name
2747          * @return bool
2748          */
2749         public function isQuotedIdentifier( $name ) {
2750                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2751         }
2752
2753         /**
2754          * @param string $s
2755          * @param string $escapeChar
2756          * @return string
2757          */
2758         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2759                 return str_replace( [ $escapeChar, '%', '_' ],
2760                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2761                         $s );
2762         }
2763
2764         public function buildLike( $param, ...$params ) {
2765                 if ( is_array( $param ) ) {
2766                         $params = $param;
2767                 } else {
2768                         $params = func_get_args();
2769                 }
2770
2771                 $s = '';
2772
2773                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2774                 // may escape backslashes, creating problems of double escaping. The `
2775                 // character has good cross-DBMS compatibility, avoiding special operators
2776                 // in MS SQL like ^ and %
2777                 $escapeChar = '`';
2778
2779                 foreach ( $params as $value ) {
2780                         if ( $value instanceof LikeMatch ) {
2781                                 $s .= $value->toString();
2782                         } else {
2783                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2784                         }
2785                 }
2786
2787                 return ' LIKE ' .
2788                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2789         }
2790
2791         public function anyChar() {
2792                 return new LikeMatch( '_' );
2793         }
2794
2795         public function anyString() {
2796                 return new LikeMatch( '%' );
2797         }
2798
2799         public function nextSequenceValue( $seqName ) {
2800                 return null;
2801         }
2802
2803         /**
2804          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2805          * is only needed because a) MySQL must be as efficient as possible due to
2806          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2807          * which index to pick. Anyway, other databases might have different
2808          * indexes on a given table. So don't bother overriding this unless you're
2809          * MySQL.
2810          * @param string $index
2811          * @return string
2812          */
2813         public function useIndexClause( $index ) {
2814                 return '';
2815         }
2816
2817         /**
2818          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2819          * is only needed because a) MySQL must be as efficient as possible due to
2820          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2821          * which index to pick. Anyway, other databases might have different
2822          * indexes on a given table. So don't bother overriding this unless you're
2823          * MySQL.
2824          * @param string $index
2825          * @return string
2826          */
2827         public function ignoreIndexClause( $index ) {
2828                 return '';
2829         }
2830
2831         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2832                 if ( count( $rows ) == 0 ) {
2833                         return;
2834                 }
2835
2836                 $uniqueIndexes = (array)$uniqueIndexes;
2837                 // Single row case
2838                 if ( !is_array( reset( $rows ) ) ) {
2839                         $rows = [ $rows ];
2840                 }
2841
2842                 try {
2843                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2844                         $affectedRowCount = 0;
2845                         foreach ( $rows as $row ) {
2846                                 // Delete rows which collide with this one
2847                                 $indexWhereClauses = [];
2848                                 foreach ( $uniqueIndexes as $index ) {
2849                                         $indexColumns = (array)$index;
2850                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2851                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2852                                                 throw new DBUnexpectedError(
2853                                                         $this,
2854                                                         'New record does not provide all values for unique key (' .
2855                                                         implode( ', ', $indexColumns ) . ')'
2856                                                 );
2857                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2858                                                 throw new DBUnexpectedError(
2859                                                         $this,
2860                                                         'New record has a null value for unique key (' .
2861                                                         implode( ', ', $indexColumns ) . ')'
2862                                                 );
2863                                         }
2864                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2865                                 }
2866
2867                                 if ( $indexWhereClauses ) {
2868                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2869                                         $affectedRowCount += $this->affectedRows();
2870                                 }
2871
2872                                 // Now insert the row
2873                                 $this->insert( $table, $row, $fname );
2874                                 $affectedRowCount += $this->affectedRows();
2875                         }
2876                         $this->endAtomic( $fname );
2877                         $this->affectedRowCount = $affectedRowCount;
2878                 } catch ( Exception $e ) {
2879                         $this->cancelAtomic( $fname );
2880                         throw $e;
2881                 }
2882         }
2883
2884         /**
2885          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2886          * statement.
2887          *
2888          * @param string $table Table name
2889          * @param array|string $rows Row(s) to insert
2890          * @param string $fname Caller function name
2891          */
2892         protected function nativeReplace( $table, $rows, $fname ) {
2893                 $table = $this->tableName( $table );
2894
2895                 # Single row case
2896                 if ( !is_array( reset( $rows ) ) ) {
2897                         $rows = [ $rows ];
2898                 }
2899
2900                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2901                 $first = true;
2902
2903                 foreach ( $rows as $row ) {
2904                         if ( $first ) {
2905                                 $first = false;
2906                         } else {
2907                                 $sql .= ',';
2908                         }
2909
2910                         $sql .= '(' . $this->makeList( $row ) . ')';
2911                 }
2912
2913                 $this->query( $sql, $fname );
2914         }
2915
2916         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2917                 $fname = __METHOD__
2918         ) {
2919                 if ( $rows === [] ) {
2920                         return true; // nothing to do
2921                 }
2922
2923                 $uniqueIndexes = (array)$uniqueIndexes;
2924                 if ( !is_array( reset( $rows ) ) ) {
2925                         $rows = [ $rows ];
2926                 }
2927
2928                 if ( count( $uniqueIndexes ) ) {
2929                         $clauses = []; // list WHERE clauses that each identify a single row
2930                         foreach ( $rows as $row ) {
2931                                 foreach ( $uniqueIndexes as $index ) {
2932                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2933                                         $rowKey = []; // unique key to this row
2934                                         foreach ( $index as $column ) {
2935                                                 $rowKey[$column] = $row[$column];
2936                                         }
2937                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2938                                 }
2939                         }
2940                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2941                 } else {
2942                         $where = false;
2943                 }
2944
2945                 $affectedRowCount = 0;
2946                 try {
2947                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2948                         # Update any existing conflicting row(s)
2949                         if ( $where !== false ) {
2950                                 $this->update( $table, $set, $where, $fname );
2951                                 $affectedRowCount += $this->affectedRows();
2952                         }
2953                         # Now insert any non-conflicting row(s)
2954                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2955                         $affectedRowCount += $this->affectedRows();
2956                         $this->endAtomic( $fname );
2957                         $this->affectedRowCount = $affectedRowCount;
2958                 } catch ( Exception $e ) {
2959                         $this->cancelAtomic( $fname );
2960                         throw $e;
2961                 }
2962
2963                 return true;
2964         }
2965
2966         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2967                 $fname = __METHOD__
2968         ) {
2969                 if ( !$conds ) {
2970                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2971                 }
2972
2973                 $delTable = $this->tableName( $delTable );
2974                 $joinTable = $this->tableName( $joinTable );
2975                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2976                 if ( $conds != '*' ) {
2977                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2978                 }
2979                 $sql .= ')';
2980
2981                 $this->query( $sql, $fname );
2982         }
2983
2984         public function textFieldSize( $table, $field ) {
2985                 $table = $this->tableName( $table );
2986                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2987                 $res = $this->query( $sql, __METHOD__ );
2988                 $row = $this->fetchObject( $res );
2989
2990                 $m = [];
2991
2992                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2993                         $size = $m[1];
2994                 } else {
2995                         $size = -1;
2996                 }
2997
2998                 return $size;
2999         }
3000
3001         public function delete( $table, $conds, $fname = __METHOD__ ) {
3002                 if ( !$conds ) {
3003                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
3004                 }
3005
3006                 $table = $this->tableName( $table );
3007                 $sql = "DELETE FROM $table";
3008
3009                 if ( $conds != '*' ) {
3010                         if ( is_array( $conds ) ) {
3011                                 $conds = $this->makeList( $conds, self::LIST_AND );
3012                         }
3013                         $sql .= ' WHERE ' . $conds;
3014                 }
3015
3016                 $this->query( $sql, $fname );
3017
3018                 return true;
3019         }
3020
3021         final public function insertSelect(
3022                 $destTable, $srcTable, $varMap, $conds,
3023                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3024         ) {
3025                 static $hints = [ 'NO_AUTO_COLUMNS' ];
3026
3027                 $insertOptions = (array)$insertOptions;
3028                 $selectOptions = (array)$selectOptions;
3029
3030                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
3031                         // For massive migrations with downtime, we don't want to select everything
3032                         // into memory and OOM, so do all this native on the server side if possible.
3033                         $this->nativeInsertSelect(
3034                                 $destTable,
3035                                 $srcTable,
3036                                 $varMap,
3037                                 $conds,
3038                                 $fname,
3039                                 array_diff( $insertOptions, $hints ),
3040                                 $selectOptions,
3041                                 $selectJoinConds
3042                         );
3043                 } else {
3044                         $this->nonNativeInsertSelect(
3045                                 $destTable,
3046                                 $srcTable,
3047                                 $varMap,
3048                                 $conds,
3049                                 $fname,
3050                                 array_diff( $insertOptions, $hints ),
3051                                 $selectOptions,
3052                                 $selectJoinConds
3053                         );
3054                 }
3055
3056                 return true;
3057         }
3058
3059         /**
3060          * @param array $insertOptions INSERT options
3061          * @param array $selectOptions SELECT options
3062          * @return bool Whether an INSERT SELECT with these options will be replication safe
3063          * @since 1.31
3064          */
3065         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3066                 return true;
3067         }
3068
3069         /**
3070          * Implementation of insertSelect() based on select() and insert()
3071          *
3072          * @see IDatabase::insertSelect()
3073          * @since 1.30
3074          * @param string $destTable
3075          * @param string|array $srcTable
3076          * @param array $varMap
3077          * @param array $conds
3078          * @param string $fname
3079          * @param array $insertOptions
3080          * @param array $selectOptions
3081          * @param array $selectJoinConds
3082          */
3083         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3084                 $fname = __METHOD__,
3085                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3086         ) {
3087                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3088                 // on only the master (without needing row-based-replication). It also makes it easy to
3089                 // know how big the INSERT is going to be.
3090                 $fields = [];
3091                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3092                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3093                 }
3094                 $selectOptions[] = 'FOR UPDATE';
3095                 $res = $this->select(
3096                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3097                 );
3098                 if ( !$res ) {
3099                         return;
3100                 }
3101
3102                 try {
3103                         $affectedRowCount = 0;
3104                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3105                         $rows = [];
3106                         $ok = true;
3107                         foreach ( $res as $row ) {
3108                                 $rows[] = (array)$row;
3109
3110                                 // Avoid inserts that are too huge
3111                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3112                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3113                                         if ( !$ok ) {
3114                                                 break;
3115                                         }
3116                                         $affectedRowCount += $this->affectedRows();
3117                                         $rows = [];
3118                                 }
3119                         }
3120                         if ( $rows && $ok ) {
3121                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3122                                 if ( $ok ) {
3123                                         $affectedRowCount += $this->affectedRows();
3124                                 }
3125                         }
3126                         if ( $ok ) {
3127                                 $this->endAtomic( $fname );
3128                                 $this->affectedRowCount = $affectedRowCount;
3129                         } else {
3130                                 $this->cancelAtomic( $fname );
3131                         }
3132                 } catch ( Exception $e ) {
3133                         $this->cancelAtomic( $fname );
3134                         throw $e;
3135                 }
3136         }
3137
3138         /**
3139          * Native server-side implementation of insertSelect() for situations where
3140          * we don't want to select everything into memory
3141          *
3142          * @see IDatabase::insertSelect()
3143          * @param string $destTable
3144          * @param string|array $srcTable
3145          * @param array $varMap
3146          * @param array $conds
3147          * @param string $fname
3148          * @param array $insertOptions
3149          * @param array $selectOptions
3150          * @param array $selectJoinConds
3151          */
3152         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3153                 $fname = __METHOD__,
3154                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3155         ) {
3156                 $destTable = $this->tableName( $destTable );
3157
3158                 if ( !is_array( $insertOptions ) ) {
3159                         $insertOptions = [ $insertOptions ];
3160                 }
3161
3162                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3163
3164                 $selectSql = $this->selectSQLText(
3165                         $srcTable,
3166                         array_values( $varMap ),
3167                         $conds,
3168                         $fname,
3169                         $selectOptions,
3170                         $selectJoinConds
3171                 );
3172
3173                 $sql = "INSERT $insertOptions" .
3174                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3175                         $selectSql;
3176
3177                 $this->query( $sql, $fname );
3178         }
3179
3180         public function limitResult( $sql, $limit, $offset = false ) {
3181                 if ( !is_numeric( $limit ) ) {
3182                         throw new DBUnexpectedError(
3183                                 $this,
3184                                 "Invalid non-numeric limit passed to " . __METHOD__
3185                         );
3186                 }
3187                 // This version works in MySQL and SQLite. It will very likely need to be
3188                 // overridden for most other RDBMS subclasses.
3189                 return "$sql LIMIT "
3190                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3191                         . "{$limit} ";
3192         }
3193
3194         public function unionSupportsOrderAndLimit() {
3195                 return true; // True for almost every DB supported
3196         }
3197
3198         public function unionQueries( $sqls, $all ) {
3199                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3200
3201                 return '(' . implode( $glue, $sqls ) . ')';
3202         }
3203
3204         public function unionConditionPermutations(
3205                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3206                 $options = [], $join_conds = []
3207         ) {
3208                 // First, build the Cartesian product of $permute_conds
3209                 $conds = [ [] ];
3210                 foreach ( $permute_conds as $field => $values ) {
3211                         if ( !$values ) {
3212                                 // Skip empty $values
3213                                 continue;
3214                         }
3215                         $values = array_unique( $values ); // For sanity
3216                         $newConds = [];
3217                         foreach ( $conds as $cond ) {
3218                                 foreach ( $values as $value ) {
3219                                         $cond[$field] = $value;
3220                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3221                                 }
3222                         }
3223                         $conds = $newConds;
3224                 }
3225
3226                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3227
3228                 // If there's just one condition and no subordering, hand off to
3229                 // selectSQLText directly.
3230                 if ( count( $conds ) === 1 &&
3231                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3232                 ) {
3233                         return $this->selectSQLText(
3234                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3235                         );
3236                 }
3237
3238                 // Otherwise, we need to pull out the order and limit to apply after
3239                 // the union. Then build the SQL queries for each set of conditions in
3240                 // $conds. Then union them together (using UNION ALL, because the
3241                 // product *should* already be distinct).
3242                 $orderBy = $this->makeOrderBy( $options );
3243                 $limit = $options['LIMIT'] ?? null;
3244                 $offset = $options['OFFSET'] ?? false;
3245                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3246                 if ( !$this->unionSupportsOrderAndLimit() ) {
3247                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3248                 } else {
3249                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3250                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3251                         }
3252                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3253                                 // We need to increase the limit by the offset rather than
3254                                 // using the offset directly, otherwise it'll skip incorrectly
3255                                 // in the subqueries.
3256                                 $options['LIMIT'] = $limit + $offset;
3257                                 unset( $options['OFFSET'] );
3258                         }
3259                 }
3260
3261                 $sqls = [];
3262                 foreach ( $conds as $cond ) {
3263                         $sqls[] = $this->selectSQLText(
3264                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3265                         );
3266                 }
3267                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3268                 if ( $limit !== null ) {
3269                         $sql = $this->limitResult( $sql, $limit, $offset );
3270                 }
3271
3272                 return $sql;
3273         }
3274
3275         public function conditional( $cond, $trueVal, $falseVal ) {
3276                 if ( is_array( $cond ) ) {
3277                         $cond = $this->makeList( $cond, self::LIST_AND );
3278                 }
3279
3280                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3281         }
3282
3283         public function strreplace( $orig, $old, $new ) {
3284                 return "REPLACE({$orig}, {$old}, {$new})";
3285         }
3286
3287         public function getServerUptime() {
3288                 return 0;
3289         }
3290
3291         public function wasDeadlock() {
3292                 return false;
3293         }
3294
3295         public function wasLockTimeout() {
3296                 return false;
3297         }
3298
3299         public function wasConnectionLoss() {
3300                 return $this->wasConnectionError( $this->lastErrno() );
3301         }
3302
3303         public function wasReadOnlyError() {
3304                 return false;
3305         }
3306
3307         public function wasErrorReissuable() {
3308                 return (
3309                         $this->wasDeadlock() ||
3310                         $this->wasLockTimeout() ||
3311                         $this->wasConnectionLoss()
3312                 );
3313         }
3314
3315         /**
3316          * Do not use this method outside of Database/DBError classes
3317          *
3318          * @param int|string $errno
3319          * @return bool Whether the given query error was a connection drop
3320          */
3321         public function wasConnectionError( $errno ) {
3322                 return false;
3323         }
3324
3325         /**
3326          * @return bool Whether it is known that the last query error only caused statement rollback
3327          * @note This is for backwards compatibility for callers catching DBError exceptions in
3328          *   order to ignore problems like duplicate key errors or foriegn key violations
3329          * @since 1.31
3330          */
3331         protected function wasKnownStatementRollbackError() {
3332                 return false; // don't know; it could have caused a transaction rollback
3333         }
3334
3335         public function deadlockLoop() {
3336                 $args = func_get_args();
3337                 $function = array_shift( $args );
3338                 $tries = self::$DEADLOCK_TRIES;
3339
3340                 $this->begin( __METHOD__ );
3341
3342                 $retVal = null;
3343                 /** @var Exception $e */
3344                 $e = null;
3345                 do {
3346                         try {
3347                                 $retVal = $function( ...$args );
3348                                 break;
3349                         } catch ( DBQueryError $e ) {
3350                                 if ( $this->wasDeadlock() ) {
3351                                         // Retry after a randomized delay
3352                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3353                                 } else {
3354                                         // Throw the error back up
3355                                         throw $e;
3356                                 }
3357                         }
3358                 } while ( --$tries > 0 );
3359
3360                 if ( $tries <= 0 ) {
3361                         // Too many deadlocks; give up
3362                         $this->rollback( __METHOD__ );
3363                         throw $e;
3364                 } else {
3365                         $this->commit( __METHOD__ );
3366
3367                         return $retVal;
3368                 }
3369         }
3370
3371         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3372                 # Real waits are implemented in the subclass.
3373                 return 0;
3374         }
3375
3376         public function getReplicaPos() {
3377                 # Stub
3378                 return false;
3379         }
3380
3381         public function getMasterPos() {
3382                 # Stub
3383                 return false;
3384         }
3385
3386         public function serverIsReadOnly() {
3387                 return false;
3388         }
3389
3390         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3391                 if ( !$this->trxLevel() ) {
3392                         throw new DBUnexpectedError( $this, "No transaction is active" );
3393                 }
3394                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3395         }
3396
3397         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3398                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3399                         // Start an implicit transaction similar to how query() does
3400                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3401                         $this->trxAutomatic = true;
3402                 }
3403
3404                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3405                 if ( !$this->trxLevel() ) {
3406                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3407                 }
3408         }
3409
3410         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3411                 $this->onTransactionCommitOrIdle( $callback, $fname );
3412         }
3413
3414         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3415                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3416                         // Start an implicit transaction similar to how query() does
3417                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3418                         $this->trxAutomatic = true;
3419                 }
3420
3421                 if ( $this->trxLevel() ) {
3422                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3423                 } else {
3424                         // No transaction is active nor will start implicitly, so make one for this callback
3425                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3426                         try {
3427                                 $callback( $this );
3428                                 $this->endAtomic( __METHOD__ );
3429                         } catch ( Exception $e ) {
3430                                 $this->cancelAtomic( __METHOD__ );
3431                                 throw $e;
3432                         }
3433                 }
3434         }
3435
3436         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3437                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3438                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3439                 }
3440                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3441         }
3442
3443         /**
3444          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3445          */
3446         private function currentAtomicSectionId() {
3447                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3448                         $levelInfo = end( $this->trxAtomicLevels );
3449
3450                         return $levelInfo[1];
3451                 }
3452
3453                 return null;
3454         }
3455
3456         /**
3457          * Hoist callback ownership for callbacks in a section to a parent section.
3458          * All callbacks should have an owner that is present in trxAtomicLevels.
3459          * @param AtomicSectionIdentifier $old
3460          * @param AtomicSectionIdentifier $new
3461          */
3462         private function reassignCallbacksForSection(
3463                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3464         ) {
3465                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3466                         if ( $info[2] === $old ) {
3467                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3468                         }
3469                 }
3470                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3471                         if ( $info[2] === $old ) {
3472                                 $this->trxIdleCallbacks[$key][2] = $new;
3473                         }
3474                 }
3475                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3476                         if ( $info[2] === $old ) {
3477                                 $this->trxEndCallbacks[$key][2] = $new;
3478                         }
3479                 }
3480                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3481                         if ( $info[2] === $old ) {
3482                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3483                         }
3484                 }
3485         }
3486
3487         /**
3488          * Update callbacks that were owned by cancelled atomic sections.
3489          *
3490          * Callbacks for "on commit" should never be run if they're owned by a
3491          * section that won't be committed.
3492          *
3493          * Callbacks for "on resolution" need to reflect that the section was
3494          * rolled back, even if the transaction as a whole commits successfully.
3495          *
3496          * Callbacks for "on section cancel" should already have been consumed,
3497          * but errors during the cancellation itself can prevent that while still
3498          * destroying the section. Hoist any such callbacks to the new top section,
3499          * which we assume will itself have to be cancelled or rolled back to
3500          * resolve the error.
3501          *
3502          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3503          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3504          * @throws UnexpectedValueException
3505          */
3506         private function modifyCallbacksForCancel(
3507                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3508         ) {
3509                 // Cancel the "on commit" callbacks owned by this savepoint
3510                 $this->trxIdleCallbacks = array_filter(
3511                         $this->trxIdleCallbacks,
3512                         function ( $entry ) use ( $sectionIds ) {
3513                                 return !in_array( $entry[2], $sectionIds, true );
3514                         }
3515                 );
3516                 $this->trxPreCommitCallbacks = array_filter(
3517                         $this->trxPreCommitCallbacks,
3518                         function ( $entry ) use ( $sectionIds ) {
3519                                 return !in_array( $entry[2], $sectionIds, true );
3520                         }
3521                 );
3522                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3523                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3524                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3525                                 $callback = $entry[0];
3526                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3527                                         // @phan-suppress-next-line PhanInfiniteRecursion No recursion at all here, phan is confused
3528                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3529                                 };
3530                                 // This "on resolution" callback no longer belongs to a section.
3531                                 $this->trxEndCallbacks[$key][2] = null;
3532                         }
3533                 }
3534                 // Hoist callback ownership for section cancel callbacks to the new top section
3535                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3536                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3537                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3538                         }
3539                 }
3540         }
3541
3542         final public function setTransactionListener( $name, callable $callback = null ) {
3543                 if ( $callback ) {
3544                         $this->trxRecurringCallbacks[$name] = $callback;
3545                 } else {
3546                         unset( $this->trxRecurringCallbacks[$name] );
3547                 }
3548         }
3549
3550         /**
3551          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3552          *
3553          * This method should not be used outside of Database/LoadBalancer
3554          *
3555          * @param bool $suppress
3556          * @since 1.28
3557          */
3558         final public function setTrxEndCallbackSuppression( $suppress ) {
3559                 $this->trxEndCallbacksSuppressed = $suppress;
3560         }
3561
3562         /**
3563          * Actually consume and run any "on transaction idle/resolution" callbacks.
3564          *
3565          * This method should not be used outside of Database/LoadBalancer
3566          *
3567          * @param int $trigger IDatabase::TRIGGER_* constant
3568          * @return int Number of callbacks attempted
3569          * @since 1.20
3570          * @throws Exception
3571          */
3572         public function runOnTransactionIdleCallbacks( $trigger ) {
3573                 if ( $this->trxLevel() ) { // sanity
3574                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open' );
3575                 }
3576
3577                 if ( $this->trxEndCallbacksSuppressed ) {
3578                         return 0;
3579                 }
3580
3581                 $count = 0;
3582                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3583                 /** @var Exception $e */
3584                 $e = null; // first exception
3585                 do { // callbacks may add callbacks :)
3586                         $callbacks = array_merge(
3587                                 $this->trxIdleCallbacks,
3588                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3589                         );
3590                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3591                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3592
3593                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3594                         // But always consume them.
3595                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3596                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3597                         }
3598                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3599
3600                         foreach ( $callbacks as $callback ) {
3601                                 ++$count;
3602                                 list( $phpCallback ) = $callback;
3603                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3604                                 try {
3605                                         // @phan-suppress-next-line PhanParamTooManyCallable
3606                                         call_user_func( $phpCallback, $trigger, $this );
3607                                 } catch ( Exception $ex ) {
3608                                         call_user_func( $this->errorLogger, $ex );
3609                                         $e = $e ?: $ex;
3610                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3611                                         // their transactions are ended so other callbacks don't fail
3612                                         if ( $this->trxLevel() ) {
3613                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3614                                         }
3615                                 } finally {
3616                                         if ( $autoTrx ) {
3617                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3618                                         } else {
3619                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3620                                         }
3621                                 }
3622                         }
3623                 } while ( count( $this->trxIdleCallbacks ) );
3624
3625                 if ( $e instanceof Exception ) {
3626                         throw $e; // re-throw any first exception
3627                 }
3628
3629                 return $count;
3630         }
3631
3632         /**
3633          * Actually consume and run any "on transaction pre-commit" callbacks.
3634          *
3635          * This method should not be used outside of Database/LoadBalancer
3636          *
3637          * @since 1.22
3638          * @return int Number of callbacks attempted
3639          * @throws Exception
3640          */
3641         public function runOnTransactionPreCommitCallbacks() {
3642                 $count = 0;
3643
3644                 $e = null; // first exception
3645                 do { // callbacks may add callbacks :)
3646                         $callbacks = $this->trxPreCommitCallbacks;
3647                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3648                         foreach ( $callbacks as $callback ) {
3649                                 try {
3650                                         ++$count;
3651                                         list( $phpCallback ) = $callback;
3652                                         $phpCallback( $this );
3653                                 } catch ( Exception $ex ) {
3654                                         ( $this->errorLogger )( $ex );
3655                                         $e = $e ?: $ex;
3656                                 }
3657                         }
3658                 } while ( count( $this->trxPreCommitCallbacks ) );
3659
3660                 if ( $e instanceof Exception ) {
3661                         throw $e; // re-throw any first exception
3662                 }
3663
3664                 return $count;
3665         }
3666
3667         /**
3668          * Actually run any "atomic section cancel" callbacks.
3669          *
3670          * @param int $trigger IDatabase::TRIGGER_* constant
3671          * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
3672          *  null on transaction rollback
3673          */
3674         private function runOnAtomicSectionCancelCallbacks(
3675                 $trigger, array $sectionIds = null
3676         ) {
3677                 /** @var Exception|Throwable $e */
3678                 $e = null; // first exception
3679
3680                 $notCancelled = [];
3681                 do {
3682                         $callbacks = $this->trxSectionCancelCallbacks;
3683                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3684                         foreach ( $callbacks as $entry ) {
3685                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3686                                         try {
3687                                                 $entry[0]( $trigger, $this );
3688                                         } catch ( Exception $ex ) {
3689                                                 ( $this->errorLogger )( $ex );
3690                                                 $e = $e ?: $ex;
3691                                         } catch ( Throwable $ex ) {
3692                                                 // @todo: Log?
3693                                                 $e = $e ?: $ex;
3694                                         }
3695                                 } else {
3696                                         $notCancelled[] = $entry;
3697                                 }
3698                         }
3699                 } while ( count( $this->trxSectionCancelCallbacks ) );
3700                 $this->trxSectionCancelCallbacks = $notCancelled;
3701
3702                 if ( $e !== null ) {
3703                         throw $e; // re-throw any first Exception/Throwable
3704                 }
3705         }
3706
3707         /**
3708          * Actually run any "transaction listener" callbacks.
3709          *
3710          * This method should not be used outside of Database/LoadBalancer
3711          *
3712          * @param int $trigger IDatabase::TRIGGER_* constant
3713          * @throws Exception
3714          * @since 1.20
3715          */
3716         public function runTransactionListenerCallbacks( $trigger ) {
3717                 if ( $this->trxEndCallbacksSuppressed ) {
3718                         return;
3719                 }
3720
3721                 /** @var Exception $e */
3722                 $e = null; // first exception
3723
3724                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3725                         try {
3726                                 $phpCallback( $trigger, $this );
3727                         } catch ( Exception $ex ) {
3728                                 ( $this->errorLogger )( $ex );
3729                                 $e = $e ?: $ex;
3730                         }
3731                 }
3732
3733                 if ( $e instanceof Exception ) {
3734                         throw $e; // re-throw any first exception
3735                 }
3736         }
3737
3738         /**
3739          * Create a savepoint
3740          *
3741          * This is used internally to implement atomic sections. It should not be
3742          * used otherwise.
3743          *
3744          * @since 1.31
3745          * @param string $identifier Identifier for the savepoint
3746          * @param string $fname Calling function name
3747          */
3748         protected function doSavepoint( $identifier, $fname ) {
3749                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3750         }
3751
3752         /**
3753          * Release a savepoint
3754          *
3755          * This is used internally to implement atomic sections. It should not be
3756          * used otherwise.
3757          *
3758          * @since 1.31
3759          * @param string $identifier Identifier for the savepoint
3760          * @param string $fname Calling function name
3761          */
3762         protected function doReleaseSavepoint( $identifier, $fname ) {
3763                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3764         }
3765
3766         /**
3767          * Rollback to a savepoint
3768          *
3769          * This is used internally to implement atomic sections. It should not be
3770          * used otherwise.
3771          *
3772          * @since 1.31
3773          * @param string $identifier Identifier for the savepoint
3774          * @param string $fname Calling function name
3775          */
3776         protected function doRollbackToSavepoint( $identifier, $fname ) {
3777                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3778         }
3779
3780         /**
3781          * @param string $fname
3782          * @return string
3783          */
3784         private function nextSavepointId( $fname ) {
3785                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3786                 if ( strlen( $savepointId ) > 30 ) {
3787                         // 30 == Oracle's identifier length limit (pre 12c)
3788                         // With a 22 character prefix, that puts the highest number at 99999999.
3789                         throw new DBUnexpectedError(
3790                                 $this,
3791                                 'There have been an excessively large number of atomic sections in a transaction'
3792                                 . " started by $this->trxFname (at $fname)"
3793                         );
3794                 }
3795
3796                 return $savepointId;
3797         }
3798
3799         final public function startAtomic(
3800                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3801         ) {
3802                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3803
3804                 if ( !$this->trxLevel() ) {
3805                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3806                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3807                         // in all changes being in one transaction to keep requests transactional.
3808                         if ( $this->getFlag( self::DBO_TRX ) ) {
3809                                 // Since writes could happen in between the topmost atomic sections as part
3810                                 // of the transaction, those sections will need savepoints.
3811                                 $savepointId = $this->nextSavepointId( $fname );
3812                                 $this->doSavepoint( $savepointId, $fname );
3813                         } else {
3814                                 $this->trxAutomaticAtomic = true;
3815                         }
3816                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3817                         $savepointId = $this->nextSavepointId( $fname );
3818                         $this->doSavepoint( $savepointId, $fname );
3819                 }
3820
3821                 $sectionId = new AtomicSectionIdentifier;
3822                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3823                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3824                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3825
3826                 return $sectionId;
3827         }
3828
3829         final public function endAtomic( $fname = __METHOD__ ) {
3830                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3831                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3832                 }
3833
3834                 // Check if the current section matches $fname
3835                 $pos = count( $this->trxAtomicLevels ) - 1;
3836                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3837                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3838
3839                 if ( $savedFname !== $fname ) {
3840                         throw new DBUnexpectedError(
3841                                 $this,
3842                                 "Invalid atomic section ended (got $fname but expected $savedFname)"
3843                         );
3844                 }
3845
3846                 // Remove the last section (no need to re-index the array)
3847                 array_pop( $this->trxAtomicLevels );
3848
3849                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3850                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3851                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3852                         $this->doReleaseSavepoint( $savepointId, $fname );
3853                 }
3854
3855                 // Hoist callback ownership for callbacks in the section that just ended;
3856                 // all callbacks should have an owner that is present in trxAtomicLevels.
3857                 $currentSectionId = $this->currentAtomicSectionId();
3858                 if ( $currentSectionId ) {
3859                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3860                 }
3861         }
3862
3863         final public function cancelAtomic(
3864                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3865         ) {
3866                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3867                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3868                 }
3869
3870                 $excisedIds = [];
3871                 $newTopSection = $this->currentAtomicSectionId();
3872                 try {
3873                         $excisedFnames = [];
3874                         if ( $sectionId !== null ) {
3875                                 // Find the (last) section with the given $sectionId
3876                                 $pos = -1;
3877                                 foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3878                                         if ( $asId === $sectionId ) {
3879                                                 $pos = $i;
3880                                         }
3881                                 }
3882                                 if ( $pos < 0 ) {
3883                                         throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3884                                 }
3885                                 // Remove all descendant sections and re-index the array
3886                                 $len = count( $this->trxAtomicLevels );
3887                                 for ( $i = $pos + 1; $i < $len; ++$i ) {
3888                                         $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3889                                         $excisedIds[] = $this->trxAtomicLevels[$i][1];
3890                                 }
3891                                 $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3892                                 $newTopSection = $this->currentAtomicSectionId();
3893                         }
3894
3895                         // Check if the current section matches $fname
3896                         $pos = count( $this->trxAtomicLevels ) - 1;
3897                         list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3898
3899                         if ( $excisedFnames ) {
3900                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3901                                         "and descendants " . implode( ', ', $excisedFnames ) );
3902                         } else {
3903                                 $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3904                         }
3905
3906                         if ( $savedFname !== $fname ) {
3907                                 throw new DBUnexpectedError(
3908                                         $this,
3909                                         "Invalid atomic section ended (got $fname but expected $savedFname)"
3910                                 );
3911                         }
3912
3913                         // Remove the last section (no need to re-index the array)
3914                         array_pop( $this->trxAtomicLevels );
3915                         $excisedIds[] = $savedSectionId;
3916                         $newTopSection = $this->currentAtomicSectionId();
3917
3918                         if ( $savepointId !== null ) {
3919                                 // Rollback the transaction to the state just before this atomic section
3920                                 if ( $savepointId === self::$NOT_APPLICABLE ) {
3921                                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3922                                         // Note: rollback() will run trxSectionCancelCallbacks
3923                                 } else {
3924                                         $this->doRollbackToSavepoint( $savepointId, $fname );
3925                                         $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3926                                         $this->trxStatusIgnoredCause = null;
3927
3928                                         // Run trxSectionCancelCallbacks now.
3929                                         $this->runOnAtomicSectionCancelCallbacks( self::TRIGGER_CANCEL, $excisedIds );
3930                                 }
3931                         } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3932                                 // Put the transaction into an error state if it's not already in one
3933                                 $this->trxStatus = self::STATUS_TRX_ERROR;
3934                                 $this->trxStatusCause = new DBUnexpectedError(
3935                                         $this,
3936                                         "Uncancelable atomic section canceled (got $fname)"
3937                                 );
3938                         }
3939                 } finally {
3940                         // Fix up callbacks owned by the sections that were just cancelled.
3941                         // All callbacks should have an owner that is present in trxAtomicLevels.
3942                         $this->modifyCallbacksForCancel( $excisedIds, $newTopSection );
3943                 }
3944
3945                 $this->affectedRowCount = 0; // for the sake of consistency
3946         }
3947
3948         final public function doAtomicSection(
3949                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3950         ) {
3951                 $sectionId = $this->startAtomic( $fname, $cancelable );
3952                 try {
3953                         $res = $callback( $this, $fname );
3954                 } catch ( Exception $e ) {
3955                         $this->cancelAtomic( $fname, $sectionId );
3956
3957                         throw $e;
3958                 }
3959                 $this->endAtomic( $fname );
3960
3961                 return $res;
3962         }
3963
3964         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3965                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3966                 if ( !in_array( $mode, $modes, true ) ) {
3967                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'" );
3968                 }
3969
3970                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3971                 if ( $this->trxLevel() ) {
3972                         if ( $this->trxAtomicLevels ) {
3973                                 $levels = $this->flatAtomicSectionList();
3974                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open";
3975                                 throw new DBUnexpectedError( $this, $msg );
3976                         } elseif ( !$this->trxAutomatic ) {
3977                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname})";
3978                                 throw new DBUnexpectedError( $this, $msg );
3979                         } else {
3980                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname})";
3981                                 throw new DBUnexpectedError( $this, $msg );
3982                         }
3983                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3984                         $msg = "$fname: Implicit transaction expected (DBO_TRX set)";
3985                         throw new DBUnexpectedError( $this, $msg );
3986                 }
3987
3988                 $this->assertHasConnectionHandle();
3989
3990                 $this->doBegin( $fname );
3991                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3992                 $this->trxStatus = self::STATUS_TRX_OK;
3993                 $this->trxStatusIgnoredCause = null;
3994                 $this->trxAtomicCounter = 0;
3995                 $this->trxTimestamp = microtime( true );
3996                 $this->trxFname = $fname;
3997                 $this->trxDoneWrites = false;
3998                 $this->trxAutomaticAtomic = false;
3999                 $this->trxAtomicLevels = [];
4000                 $this->trxWriteDuration = 0.0;
4001                 $this->trxWriteQueryCount = 0;
4002                 $this->trxWriteAffectedRows = 0;
4003                 $this->trxWriteAdjDuration = 0.0;
4004                 $this->trxWriteAdjQueryCount = 0;
4005                 $this->trxWriteCallers = [];
4006                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
4007                 // Get an estimate of the replication lag before any such queries.
4008                 $this->trxReplicaLag = null; // clear cached value first
4009                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
4010                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
4011                 // caller will think its OK to muck around with the transaction just because startAtomic()
4012                 // has not yet completed (e.g. setting trxAtomicLevels).
4013                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
4014         }
4015
4016         /**
4017          * Issues the BEGIN command to the database server.
4018          *
4019          * @see Database::begin()
4020          * @param string $fname
4021          * @throws DBError
4022          */
4023         protected function doBegin( $fname ) {
4024                 $this->query( 'BEGIN', $fname );
4025         }
4026
4027         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4028                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
4029                 if ( !in_array( $flush, $modes, true ) ) {
4030                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'" );
4031                 }
4032
4033                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
4034                         // There are still atomic sections open; this cannot be ignored
4035                         $levels = $this->flatAtomicSectionList();
4036                         throw new DBUnexpectedError(
4037                                 $this,
4038                                 "$fname: Got COMMIT while atomic sections $levels are still open"
4039                         );
4040                 }
4041
4042                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
4043                         if ( !$this->trxLevel() ) {
4044                                 return; // nothing to do
4045                         } elseif ( !$this->trxAutomatic ) {
4046                                 throw new DBUnexpectedError(
4047                                         $this,
4048                                         "$fname: Flushing an explicit transaction, getting out of sync"
4049                                 );
4050                         }
4051                 } elseif ( !$this->trxLevel() ) {
4052                         $this->queryLogger->error(
4053                                 "$fname: No transaction to commit, something got out of sync" );
4054                         return; // nothing to do
4055                 } elseif ( $this->trxAutomatic ) {
4056                         throw new DBUnexpectedError(
4057                                 $this,
4058                                 "$fname: Expected mass commit of all peer transactions (DBO_TRX set)"
4059                         );
4060                 }
4061
4062                 $this->assertHasConnectionHandle();
4063
4064                 $this->runOnTransactionPreCommitCallbacks();
4065
4066                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
4067                 $this->doCommit( $fname );
4068                 $oldTrxShortId = $this->consumeTrxShortId();
4069                 $this->trxStatus = self::STATUS_TRX_NONE;
4070
4071                 if ( $this->trxDoneWrites ) {
4072                         $this->lastWriteTime = microtime( true );
4073                         $this->trxProfiler->transactionWritingOut(
4074                                 $this->server,
4075                                 $this->getDomainID(),
4076                                 $oldTrxShortId,
4077                                 $writeTime,
4078                                 $this->trxWriteAffectedRows
4079                         );
4080                 }
4081
4082                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4083                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
4084                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
4085                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
4086                 }
4087         }
4088
4089         /**
4090          * Issues the COMMIT command to the database server.
4091          *
4092          * @see Database::commit()
4093          * @param string $fname
4094          * @throws DBError
4095          */
4096         protected function doCommit( $fname ) {
4097                 if ( $this->trxLevel() ) {
4098                         $this->query( 'COMMIT', $fname );
4099                 }
4100         }
4101
4102         final public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4103                 $trxActive = $this->trxLevel();
4104
4105                 if ( $flush !== self::FLUSHING_INTERNAL
4106                         && $flush !== self::FLUSHING_ALL_PEERS
4107                         && $this->getFlag( self::DBO_TRX )
4108                 ) {
4109                         throw new DBUnexpectedError(
4110                                 $this,
4111                                 "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)"
4112                         );
4113                 }
4114
4115                 if ( $trxActive ) {
4116                         $this->assertHasConnectionHandle();
4117
4118                         $this->doRollback( $fname );
4119                         $oldTrxShortId = $this->consumeTrxShortId();
4120                         $this->trxStatus = self::STATUS_TRX_NONE;
4121                         $this->trxAtomicLevels = [];
4122                         // Estimate the RTT via a query now that trxStatus is OK
4123                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
4124
4125                         if ( $this->trxDoneWrites ) {
4126                                 $this->trxProfiler->transactionWritingOut(
4127                                         $this->server,
4128                                         $this->getDomainID(),
4129                                         $oldTrxShortId,
4130                                         $writeTime,
4131                                         $this->trxWriteAffectedRows
4132                                 );
4133                         }
4134                 }
4135
4136                 // Clear any commit-dependant callbacks. They might even be present
4137                 // only due to transaction rounds, with no SQL transaction being active
4138                 $this->trxIdleCallbacks = [];
4139                 $this->trxPreCommitCallbacks = [];
4140
4141                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4142                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4143                         try {
4144                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4145                         } catch ( Exception $e ) {
4146                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4147                         }
4148                         try {
4149                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4150                         } catch ( Exception $e ) {
4151                                 // already logged; let LoadBalancer move on during mass-rollback
4152                         }
4153
4154                         $this->affectedRowCount = 0; // for the sake of consistency
4155                 }
4156         }
4157
4158         /**
4159          * Issues the ROLLBACK command to the database server.
4160          *
4161          * @see Database::rollback()
4162          * @param string $fname
4163          * @throws DBError
4164          */
4165         protected function doRollback( $fname ) {
4166                 if ( $this->trxLevel() ) {
4167                         # Disconnects cause rollback anyway, so ignore those errors
4168                         $ignoreErrors = true;
4169                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4170                 }
4171         }
4172
4173         public function flushSnapshot( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
4174                 if ( $this->explicitTrxActive() ) {
4175                         // Committing this transaction would break callers that assume it is still open
4176                         throw new DBUnexpectedError(
4177                                 $this,
4178                                 "$fname: Cannot flush snapshot; " .
4179                                 "explicit transaction '{$this->trxFname}' is still open"
4180                         );
4181                 } elseif ( $this->writesOrCallbacksPending() ) {
4182                         // This only flushes transactions to clear snapshots, not to write data
4183                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4184                         throw new DBUnexpectedError(
4185                                 $this,
4186                                 "$fname: Cannot flush snapshot; " .
4187                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4188                         );
4189                 } elseif (
4190                         $this->trxLevel() &&
4191                         $this->getTransactionRoundId() &&
4192                         $flush !== self::FLUSHING_INTERNAL &&
4193                         $flush !== self::FLUSHING_ALL_PEERS
4194                 ) {
4195                         $this->queryLogger->warning(
4196                                 "$fname: Expected mass snapshot flush of all peer transactions " .
4197                                 "in the explicit transactions round '{$this->getTransactionRoundId()}'",
4198                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4199                         );
4200                 }
4201
4202                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4203         }
4204
4205         public function explicitTrxActive() {
4206                 return $this->trxLevel() && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4207         }
4208
4209         public function duplicateTableStructure(
4210                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4211         ) {
4212                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4213         }
4214
4215         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4216                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4217         }
4218
4219         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4220                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4221         }
4222
4223         public function timestamp( $ts = 0 ) {
4224                 $t = new ConvertibleTimestamp( $ts );
4225                 // Let errors bubble up to avoid putting garbage in the DB
4226                 return $t->getTimestamp( TS_MW );
4227         }
4228
4229         public function timestampOrNull( $ts = null ) {
4230                 if ( is_null( $ts ) ) {
4231                         return null;
4232                 } else {
4233                         return $this->timestamp( $ts );
4234                 }
4235         }
4236
4237         public function affectedRows() {
4238                 return ( $this->affectedRowCount === null )
4239                         ? $this->fetchAffectedRowCount() // default to driver value
4240                         : $this->affectedRowCount;
4241         }
4242
4243         /**
4244          * @return int Number of retrieved rows according to the driver
4245          */
4246         abstract protected function fetchAffectedRowCount();
4247
4248         /**
4249          * Take a query result and wrap it in an iterable result wrapper if necessary.
4250          * Booleans are passed through as-is to indicate success/failure of write queries.
4251          *
4252          * Once upon a time, Database::query() returned a bare MySQL result
4253          * resource, and it was necessary to call this function to convert it to
4254          * a wrapper. Nowadays, raw database objects are never exposed to external
4255          * callers, so this is unnecessary in external code.
4256          *
4257          * @param bool|IResultWrapper|resource $result
4258          * @return bool|IResultWrapper
4259          */
4260         protected function resultObject( $result ) {
4261                 if ( !$result ) {
4262                         return false; // failed query
4263                 } elseif ( $result instanceof IResultWrapper ) {
4264                         return $result;
4265                 } elseif ( $result === true ) {
4266                         return $result; // succesful write query
4267                 } else {
4268                         return new ResultWrapper( $this, $result );
4269                 }
4270         }
4271
4272         public function ping( &$rtt = null ) {
4273                 // Avoid hitting the server if it was hit recently
4274                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::$PING_TTL ) {
4275                         if ( !func_num_args() || $this->lastRoundTripEstimate > 0 ) {
4276                                 $rtt = $this->lastRoundTripEstimate;
4277                                 return true; // don't care about $rtt
4278                         }
4279                 }
4280
4281                 // This will reconnect if possible or return false if not
4282                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4283                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, true ) !== false );
4284                 $this->restoreFlags( self::RESTORE_PRIOR );
4285
4286                 if ( $ok ) {
4287                         $rtt = $this->lastRoundTripEstimate;
4288                 }
4289
4290                 return $ok;
4291         }
4292
4293         /**
4294          * Close any existing (dead) database connection and open a new connection
4295          *
4296          * @param string $fname
4297          * @return bool True if new connection is opened successfully, false if error
4298          */
4299         protected function replaceLostConnection( $fname ) {
4300                 $this->closeConnection();
4301                 $this->conn = null;
4302
4303                 $this->handleSessionLossPreconnect();
4304
4305                 try {
4306                         $this->open(
4307                                 $this->server,
4308                                 $this->user,
4309                                 $this->password,
4310                                 $this->currentDomain->getDatabase(),
4311                                 $this->currentDomain->getSchema(),
4312                                 $this->tablePrefix()
4313                         );
4314                         $this->lastPing = microtime( true );
4315                         $ok = true;
4316
4317                         $this->connLogger->warning(
4318                                 $fname . ': lost connection to {dbserver}; reconnected',
4319                                 [
4320                                         'dbserver' => $this->getServer(),
4321                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4322                                 ]
4323                         );
4324                 } catch ( DBConnectionError $e ) {
4325                         $ok = false;
4326
4327                         $this->connLogger->error(
4328                                 $fname . ': lost connection to {dbserver} permanently',
4329                                 [ 'dbserver' => $this->getServer() ]
4330                         );
4331                 }
4332
4333                 $this->handleSessionLossPostconnect();
4334
4335                 return $ok;
4336         }
4337
4338         public function getSessionLagStatus() {
4339                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4340         }
4341
4342         /**
4343          * Get the replica DB lag when the current transaction started
4344          *
4345          * This is useful when transactions might use snapshot isolation
4346          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4347          * is this lag plus transaction duration. If they don't, it is still
4348          * safe to be pessimistic. This returns null if there is no transaction.
4349          *
4350          * This returns null if the lag status for this transaction was not yet recorded.
4351          *
4352          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4353          * @since 1.27
4354          */
4355         final protected function getRecordedTransactionLagStatus() {
4356                 return ( $this->trxLevel() && $this->trxReplicaLag !== null )
4357                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4358                         : null;
4359         }
4360
4361         /**
4362          * Get a replica DB lag estimate for this server
4363          *
4364          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4365          * @since 1.27
4366          */
4367         protected function getApproximateLagStatus() {
4368                 return [
4369                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4370                         'since' => microtime( true )
4371                 ];
4372         }
4373
4374         /**
4375          * Merge the result of getSessionLagStatus() for several DBs
4376          * using the most pessimistic values to estimate the lag of
4377          * any data derived from them in combination
4378          *
4379          * This is information is useful for caching modules
4380          *
4381          * @see WANObjectCache::set()
4382          * @see WANObjectCache::getWithSetCallback()
4383          *
4384          * @param IDatabase $db1
4385          * @param IDatabase|null $db2 [optional]
4386          * @return array Map of values:
4387          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4388          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4389          *   - pending: whether any of the DBs have uncommitted changes
4390          * @throws DBError
4391          * @since 1.27
4392          */
4393         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4394                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4395                 foreach ( func_get_args() as $db ) {
4396                         /** @var IDatabase $db */
4397                         $status = $db->getSessionLagStatus();
4398                         if ( $status['lag'] === false ) {
4399                                 $res['lag'] = false;
4400                         } elseif ( $res['lag'] !== false ) {
4401                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4402                         }
4403                         $res['since'] = min( $res['since'], $status['since'] );
4404                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4405                 }
4406
4407                 return $res;
4408         }
4409
4410         public function getLag() {
4411                 if ( $this->getLBInfo( 'master' ) ) {
4412                         return 0; // this is the master
4413                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4414                         return 0; // static dataset
4415                 }
4416
4417                 return $this->doGetLag();
4418         }
4419
4420         protected function doGetLag() {
4421                 return 0;
4422         }
4423
4424         public function maxListLen() {
4425                 return 0;
4426         }
4427
4428         public function encodeBlob( $b ) {
4429                 return $b;
4430         }
4431
4432         public function decodeBlob( $b ) {
4433                 if ( $b instanceof Blob ) {
4434                         $b = $b->fetch();
4435                 }
4436                 return $b;
4437         }
4438
4439         public function setSessionOptions( array $options ) {
4440         }
4441
4442         public function sourceFile(
4443                 $filename,
4444                 callable $lineCallback = null,
4445                 callable $resultCallback = null,
4446                 $fname = false,
4447                 callable $inputCallback = null
4448         ) {
4449                 AtEase::suppressWarnings();
4450                 $fp = fopen( $filename, 'r' );
4451                 AtEase::restoreWarnings();
4452
4453                 if ( $fp === false ) {
4454                         throw new RuntimeException( "Could not open \"{$filename}\"" );
4455                 }
4456
4457                 if ( !$fname ) {
4458                         $fname = __METHOD__ . "( $filename )";
4459                 }
4460
4461                 try {
4462                         $error = $this->sourceStream(
4463                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4464                 } catch ( Exception $e ) {
4465                         fclose( $fp );
4466                         throw $e;
4467                 }
4468
4469                 fclose( $fp );
4470
4471                 return $error;
4472         }
4473
4474         public function setSchemaVars( $vars ) {
4475                 $this->schemaVars = $vars;
4476         }
4477
4478         public function sourceStream(
4479                 $fp,
4480                 callable $lineCallback = null,
4481                 callable $resultCallback = null,
4482                 $fname = __METHOD__,
4483                 callable $inputCallback = null
4484         ) {
4485                 $delimiterReset = new ScopedCallback(
4486                         function ( $delimiter ) {
4487                                 $this->delimiter = $delimiter;
4488                         },
4489                         [ $this->delimiter ]
4490                 );
4491                 $cmd = '';
4492
4493                 while ( !feof( $fp ) ) {
4494                         if ( $lineCallback ) {
4495                                 call_user_func( $lineCallback );
4496                         }
4497
4498                         $line = trim( fgets( $fp ) );
4499
4500                         if ( $line == '' ) {
4501                                 continue;
4502                         }
4503
4504                         if ( $line[0] == '-' && $line[1] == '-' ) {
4505                                 continue;
4506                         }
4507
4508                         if ( $cmd != '' ) {
4509                                 $cmd .= ' ';
4510                         }
4511
4512                         $done = $this->streamStatementEnd( $cmd, $line );
4513
4514                         $cmd .= "$line\n";
4515
4516                         if ( $done || feof( $fp ) ) {
4517                                 $cmd = $this->replaceVars( $cmd );
4518
4519                                 if ( $inputCallback ) {
4520                                         $callbackResult = $inputCallback( $cmd );
4521
4522                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4523                                                 $cmd = $callbackResult;
4524                                         }
4525                                 }
4526
4527                                 if ( $cmd ) {
4528                                         $res = $this->query( $cmd, $fname );
4529
4530                                         if ( $resultCallback ) {
4531                                                 $resultCallback( $res, $this );
4532                                         }
4533
4534                                         if ( $res === false ) {
4535                                                 $err = $this->lastError();
4536
4537                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4538                                         }
4539                                 }
4540                                 $cmd = '';
4541                         }
4542                 }
4543
4544                 ScopedCallback::consume( $delimiterReset );
4545                 return true;
4546         }
4547
4548         /**
4549          * Called by sourceStream() to check if we've reached a statement end
4550          *
4551          * @param string &$sql SQL assembled so far
4552          * @param string &$newLine New line about to be added to $sql
4553          * @return bool Whether $newLine contains end of the statement
4554          */
4555         public function streamStatementEnd( &$sql, &$newLine ) {
4556                 if ( $this->delimiter ) {
4557                         $prev = $newLine;
4558                         $newLine = preg_replace(
4559                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4560                         if ( $newLine != $prev ) {
4561                                 return true;
4562                         }
4563                 }
4564
4565                 return false;
4566         }
4567
4568         /**
4569          * Database independent variable replacement. Replaces a set of variables
4570          * in an SQL statement with their contents as given by $this->getSchemaVars().
4571          *
4572          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4573          *
4574          * - '{$var}' should be used for text and is passed through the database's
4575          *   addQuotes method.
4576          * - `{$var}` should be used for identifiers (e.g. table and database names).
4577          *   It is passed through the database's addIdentifierQuotes method which
4578          *   can be overridden if the database uses something other than backticks.
4579          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4580          *   database's tableName method.
4581          * - / *i* / passes the name that follows through the database's indexName method.
4582          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4583          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4584          *
4585          * @param string $ins SQL statement to replace variables in
4586          * @return string The new SQL statement with variables replaced
4587          */
4588         protected function replaceVars( $ins ) {
4589                 $vars = $this->getSchemaVars();
4590                 return preg_replace_callback(
4591                         '!
4592                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4593                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4594                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4595                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4596                         !x',
4597                         function ( $m ) use ( $vars ) {
4598                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4599                                 // check for both nonexistent keys *and* the empty string.
4600                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4601                                         if ( $m[1] === 'i' ) {
4602                                                 return $this->indexName( $m[2] );
4603                                         } else {
4604                                                 return $this->tableName( $m[2] );
4605                                         }
4606                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4607                                         return $this->addQuotes( $vars[$m[3]] );
4608                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4609                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4610                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4611                                         return $vars[$m[5]];
4612                                 } else {
4613                                         return $m[0];
4614                                 }
4615                         },
4616                         $ins
4617                 );
4618         }
4619
4620         /**
4621          * Get schema variables. If none have been set via setSchemaVars(), then
4622          * use some defaults from the current object.
4623          *
4624          * @return array
4625          */
4626         protected function getSchemaVars() {
4627                 if ( $this->schemaVars ) {
4628                         return $this->schemaVars;
4629                 } else {
4630                         return $this->getDefaultSchemaVars();
4631                 }
4632         }
4633
4634         /**
4635          * Get schema variables to use if none have been set via setSchemaVars().
4636          *
4637          * Override this in derived classes to provide variables for tables.sql
4638          * and SQL patch files.
4639          *
4640          * @return array
4641          */
4642         protected function getDefaultSchemaVars() {
4643                 return [];
4644         }
4645
4646         public function lockIsFree( $lockName, $method ) {
4647                 // RDBMs methods for checking named locks may or may not count this thread itself.
4648                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4649                 // the behavior choosen by the interface for this method.
4650                 return !isset( $this->sessionNamedLocks[$lockName] );
4651         }
4652
4653         public function lock( $lockName, $method, $timeout = 5 ) {
4654                 $this->sessionNamedLocks[$lockName] = 1;
4655
4656                 return true;
4657         }
4658
4659         public function unlock( $lockName, $method ) {
4660                 unset( $this->sessionNamedLocks[$lockName] );
4661
4662                 return true;
4663         }
4664
4665         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4666                 if ( $this->writesOrCallbacksPending() ) {
4667                         // This only flushes transactions to clear snapshots, not to write data
4668                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4669                         throw new DBUnexpectedError(
4670                                 $this,
4671                                 "$fname: Cannot flush pre-lock snapshot; " .
4672                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4673                         );
4674                 }
4675
4676                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4677                         return null;
4678                 }
4679
4680                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4681                         if ( $this->trxLevel() ) {
4682                                 // There is a good chance an exception was thrown, causing any early return
4683                                 // from the caller. Let any error handler get a chance to issue rollback().
4684                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4685                                 $this->onTransactionResolution(
4686                                         function () use ( $lockKey, $fname ) {
4687                                                 $this->unlock( $lockKey, $fname );
4688                                         },
4689                                         $fname
4690                                 );
4691                         } else {
4692                                 $this->unlock( $lockKey, $fname );
4693                         }
4694                 } );
4695
4696                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4697
4698                 return $unlocker;
4699         }
4700
4701         public function namedLocksEnqueue() {
4702                 return false;
4703         }
4704
4705         public function tableLocksHaveTransactionScope() {
4706                 return true;
4707         }
4708
4709         final public function lockTables( array $read, array $write, $method ) {
4710                 if ( $this->writesOrCallbacksPending() ) {
4711                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending" );
4712                 }
4713
4714                 if ( $this->tableLocksHaveTransactionScope() ) {
4715                         $this->startAtomic( $method );
4716                 }
4717
4718                 return $this->doLockTables( $read, $write, $method );
4719         }
4720
4721         /**
4722          * Helper function for lockTables() that handles the actual table locking
4723          *
4724          * @param array $read Array of tables to lock for read access
4725          * @param array $write Array of tables to lock for write access
4726          * @param string $method Name of caller
4727          * @return true
4728          */
4729         protected function doLockTables( array $read, array $write, $method ) {
4730                 return true;
4731         }
4732
4733         final public function unlockTables( $method ) {
4734                 if ( $this->tableLocksHaveTransactionScope() ) {
4735                         $this->endAtomic( $method );
4736
4737                         return true; // locks released on COMMIT/ROLLBACK
4738                 }
4739
4740                 return $this->doUnlockTables( $method );
4741         }
4742
4743         /**
4744          * Helper function for unlockTables() that handles the actual table unlocking
4745          *
4746          * @param string $method Name of caller
4747          * @return true
4748          */
4749         protected function doUnlockTables( $method ) {
4750                 return true;
4751         }
4752
4753         /**
4754          * Delete a table
4755          * @param string $tableName
4756          * @param string $fName
4757          * @return bool|IResultWrapper
4758          * @since 1.18
4759          */
4760         public function dropTable( $tableName, $fName = __METHOD__ ) {
4761                 if ( !$this->tableExists( $tableName, $fName ) ) {
4762                         return false;
4763                 }
4764                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4765
4766                 return $this->query( $sql, $fName );
4767         }
4768
4769         public function getInfinity() {
4770                 return 'infinity';
4771         }
4772
4773         public function encodeExpiry( $expiry ) {
4774                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4775                         ? $this->getInfinity()
4776                         : $this->timestamp( $expiry );
4777         }
4778
4779         public function decodeExpiry( $expiry, $format = TS_MW ) {
4780                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4781                         return 'infinity';
4782                 }
4783
4784                 return ConvertibleTimestamp::convert( $format, $expiry );
4785         }
4786
4787         public function setBigSelects( $value = true ) {
4788                 // no-op
4789         }
4790
4791         public function isReadOnly() {
4792                 return ( $this->getReadOnlyReason() !== false );
4793         }
4794
4795         /**
4796          * @return string|bool Reason this DB is read-only or false if it is not
4797          */
4798         protected function getReadOnlyReason() {
4799                 $reason = $this->getLBInfo( 'readOnlyReason' );
4800                 if ( is_string( $reason ) ) {
4801                         return $reason;
4802                 } elseif ( $this->getLBInfo( 'replica' ) ) {
4803                         return "Server is configured in the role of a read-only replica database.";
4804                 }
4805
4806                 return false;
4807         }
4808
4809         public function setTableAliases( array $aliases ) {
4810                 $this->tableAliases = $aliases;
4811         }
4812
4813         public function setIndexAliases( array $aliases ) {
4814                 $this->indexAliases = $aliases;
4815         }
4816
4817         /**
4818          * @param int $field
4819          * @param int $flags
4820          * @return bool
4821          */
4822         protected function hasFlags( $field, $flags ) {
4823                 return ( ( $field & $flags ) === $flags );
4824         }
4825
4826         /**
4827          * Get the underlying binding connection handle
4828          *
4829          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4830          * This catches broken callers than catch and ignore disconnection exceptions.
4831          * Unlike checking isOpen(), this is safe to call inside of open().
4832          *
4833          * @return mixed
4834          * @throws DBUnexpectedError
4835          * @since 1.26
4836          */
4837         protected function getBindingHandle() {
4838                 if ( !$this->conn ) {
4839                         throw new DBUnexpectedError(
4840                                 $this,
4841                                 'DB connection was already closed or the connection dropped'
4842                         );
4843                 }
4844
4845                 return $this->conn;
4846         }
4847
4848         public function __toString() {
4849                 // spl_object_id is PHP >= 7.2
4850                 $id = function_exists( 'spl_object_id' )
4851                         ? spl_object_id( $this )
4852                         : spl_object_hash( $this );
4853
4854                 $description = $this->getType() . ' object #' . $id;
4855                 if ( is_resource( $this->conn ) ) {
4856                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4857                 } elseif ( is_object( $this->conn ) ) {
4858                         // spl_object_id is PHP >= 7.2
4859                         $handleId = function_exists( 'spl_object_id' )
4860                                 ? spl_object_id( $this->conn )
4861                                 : spl_object_hash( $this->conn );
4862                         $description .= " (handle id #$handleId)";
4863                 }
4864
4865                 return $description;
4866         }
4867
4868         /**
4869          * Make sure that copies do not share the same client binding handle
4870          * @throws DBConnectionError
4871          */
4872         public function __clone() {
4873                 $this->connLogger->warning(
4874                         "Cloning " . static::class . " is not recommended; forking connection",
4875                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4876                 );
4877
4878                 if ( $this->isOpen() ) {
4879                         // Open a new connection resource without messing with the old one
4880                         $this->conn = null;
4881                         $this->trxEndCallbacks = []; // don't copy
4882                         $this->trxSectionCancelCallbacks = []; // don't copy
4883                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4884                         $this->open(
4885                                 $this->server,
4886                                 $this->user,
4887                                 $this->password,
4888                                 $this->currentDomain->getDatabase(),
4889                                 $this->currentDomain->getSchema(),
4890                                 $this->tablePrefix()
4891                         );
4892                         $this->lastPing = microtime( true );
4893                 }
4894         }
4895
4896         /**
4897          * Called by serialize. Throw an exception when DB connection is serialized.
4898          * This causes problems on some database engines because the connection is
4899          * not restored on unserialize.
4900          */
4901         public function __sleep() {
4902                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4903                         'the connection is not restored on wakeup' );
4904         }
4905
4906         /**
4907          * Run a few simple sanity checks and close dangling connections
4908          */
4909         public function __destruct() {
4910                 if ( $this->trxLevel() && $this->trxDoneWrites ) {
4911                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})" );
4912                 }
4913
4914                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4915                 if ( $danglingWriters ) {
4916                         $fnames = implode( ', ', $danglingWriters );
4917                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)" );
4918                 }
4919
4920                 if ( $this->conn ) {
4921                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4922                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4923                         AtEase::suppressWarnings();
4924                         $this->closeConnection();
4925                         AtEase::restoreWarnings();
4926                         $this->conn = null;
4927                 }
4928         }
4929 }
4930
4931 /**
4932  * @deprecated since 1.28
4933  */
4934 class_alias( Database::class, 'DatabaseBase' );
4935
4936 /**
4937  * @deprecated since 1.29
4938  */
4939 class_alias( Database::class, 'Database' );