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 BagOStuff APC cache */
  51         protected $srvCache;
  52         /** @var LoggerInterface */
  53         protected $connLogger;
  54         /** @var LoggerInterface */
  55         protected $queryLogger;
  56         /** @var callable Error logging callback */
  57         protected $errorLogger;
  58         /** @var callable Deprecation logging callback */
  59         protected $deprecationLogger;
  60         /** @var callable|null */
  61         protected $profiler;
  62         /** @var TransactionProfiler */
  63         protected $trxProfiler;
  64
  65         /** @var DatabaseDomain */
  66         protected $currentDomain;
  67
  68         /** @var object|resource|null Database connection */
  69         protected $conn;
  70
  71         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
  72         private $lazyMasterHandle;
  73
  74         /** @var string Server that this instance is currently connected to */
  75         protected $server;
  76         /** @var string User that this instance is currently connected under the name of */
  77         protected $user;
  78         /** @var string Password used to establish the current connection */
  79         protected $password;
  80         /** @var bool Whether this PHP instance is for a CLI script */
  81         protected $cliMode;
  82         /** @var string Agent name for query profiling */
  83         protected $agent;
  84         /** @var array Parameters used by initConnection() to establish a connection */
  85         protected $connectionParams;
  86         /** @var string[]|int[]|float[] SQL variables values to use for all new connections */
  87         protected $connectionVariables;
  88         /** @var int Row batch size to use for emulated INSERT SELECT queries */
  89         protected $nonNativeInsertSelectBatchSize;
  90
  91         /** @var int Current bit field of class DBO_* constants */
  92         protected $flags;
  93         /** @var array Current LoadBalancer tracking information */
  94         protected $lbInfo = [];
  95         /** @var string Current SQL query delimiter */
  96         protected $delimiter = ';';
  97         /** @var array[] Current map of (table => (dbname, schema, prefix) map) */
  98         protected $tableAliases = [];
  99         /** @var string[] Current map of (index alias => index) */
 100         protected $indexAliases = [];
 101         /** @var array|null Current variables use for schema element placeholders */
 102         protected $schemaVars;
 103
 104         /** @var string|bool|null Stashed value of html_errors INI setting */
 105         private $htmlErrors;
 106         /** @var int[] Prior flags member variable values */
 107         private $priorFlags = [];
 108
 109         /** @var array Map of (name => 1) for locks obtained via lock() */
 110         protected $sessionNamedLocks = [];
 111         /** @var array Map of (table name => 1) for TEMPORARY tables */
 112         protected $sessionTempTables = [];
 113
 114         /** @var string ID of the active transaction or the empty string otherwise */
 115         private $trxShortId = '';
 116         /** @var int Transaction status */
 117         private $trxStatus = self::STATUS_TRX_NONE;
 118         /** @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR */
 119         private $trxStatusCause;
 120         /** @var array|null Error details of the last statement-only rollback */
 121         private $trxStatusIgnoredCause;
 122         /** @var float|null UNIX timestamp at the time of BEGIN for the last transaction */
 123         private $trxTimestamp = null;
 124         /** @var float Replication lag estimate at the time of BEGIN for the last transaction */
 125         private $trxReplicaLag = null;
 126         /** @var string Name of the function that start the last transaction */
 127         private $trxFname = null;
 128         /** @var bool Whether possible write queries were done in the last transaction started */
 129         private $trxDoneWrites = false;
 130         /** @var bool Whether the current transaction was started implicitly due to DBO_TRX */
 131         private $trxAutomatic = false;
 132         /** @var int Counter for atomic savepoint identifiers (reset with each transaction) */
 133         private $trxAtomicCounter = 0;
 134         /** @var array List of (name, unique ID, savepoint ID) for each active atomic section level */
 135         private $trxAtomicLevels = [];
 136         /** @var bool Whether the current transaction was started implicitly by startAtomic() */
 137         private $trxAutomaticAtomic = false;
 138         /** @var string[] Write query callers of the current transaction */
 139         private $trxWriteCallers = [];
 140         /** @var float Seconds spent in write queries for the current transaction */
 141         private $trxWriteDuration = 0.0;
 142         /** @var int Number of write queries for the current transaction */
 143         private $trxWriteQueryCount = 0;
 144         /** @var int Number of rows affected by write queries for the current transaction */
 145         private $trxWriteAffectedRows = 0;
 146         /** @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries */
 147         private $trxWriteAdjDuration = 0.0;
 148         /** @var int Number of write queries counted in trxWriteAdjDuration */
 149         private $trxWriteAdjQueryCount = 0;
 150         /** @var array[] List of (callable, method name, atomic section id) */
 151         private $trxIdleCallbacks = [];
 152         /** @var array[] List of (callable, method name, atomic section id) */
 153         private $trxPreCommitCallbacks = [];
 154         /** @var array[] List of (callable, method name, atomic section id) */
 155         private $trxEndCallbacks = [];
 156         /** @var array[] List of (callable, method name, atomic section id) */
 157         private $trxSectionCancelCallbacks = [];
 158         /** @var callable[] Map of (name => callable) */
 159         private $trxRecurringCallbacks = [];
 160         /** @var bool Whether to suppress triggering of transaction end callbacks */
 161         private $trxEndCallbacksSuppressed = false;
 162
 163         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 164         protected $affectedRowCount;
 165
 166         /** @var float UNIX timestamp */
 167         private $lastPing = 0.0;
 168         /** @var string The last SQL query attempted */
 169         private $lastQuery = '';
 170         /** @var float|bool UNIX timestamp of last write query */
 171         private $lastWriteTime = false;
 172         /** @var string|bool */
 173         private $lastPhpError = false;
 174         /** @var float Query rount trip time estimate */
 175         private $lastRoundTripEstimate = 0.0;
 176
 177         /** @var string Lock granularity is on the level of the entire database */
 178         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
 179         /** @var string The SCHEMA keyword refers to a grouping of tables in a database */
 180         const ATTR_SCHEMAS_AS_TABLE_GROUPS = 'supports-schemas';
 181
 182         /** @var int New Database instance will not be connected yet when returned */
 183         const NEW_UNCONNECTED = 0;
 184         /** @var int New Database instance will already be connected when returned */
 185         const NEW_CONNECTED = 1;
 186
 187         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 188         const STATUS_TRX_ERROR = 1;
 189         /** @var int Transaction is active and in a normal state */
 190         const STATUS_TRX_OK = 2;
 191         /** @var int No transaction is active */
 192         const STATUS_TRX_NONE = 3;
 193
 194         /** @var string Idiom used when a cancelable atomic section started the transaction */
 195         private static $NOT_APPLICABLE = 'n/a';
 196         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 197         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 198
 199         /** @var int Writes to this temporary table do not affect lastDoneWrites() */
 200         private static $TEMP_NORMAL = 1;
 201         /** @var int Writes to this temporary table effect lastDoneWrites() */
 202         private static $TEMP_PSEUDO_PERMANENT = 2;
 203
 204         /** @var int Number of times to re-try an operation in case of deadlock */
 205         private static $DEADLOCK_TRIES = 4;
 206         /** @var int Minimum time to wait before retry, in microseconds */
 207         private static $DEADLOCK_DELAY_MIN = 500000;
 208         /** @var int Maximum time to wait before retry */
 209         private static $DEADLOCK_DELAY_MAX = 1500000;
 210
 211         /** @var int How long before it is worth doing a dummy query to test the connection */
 212         private static $PING_TTL = 1.0;
 213         /** @var string Dummy SQL query */
 214         private static $PING_QUERY = 'SELECT 1 AS ping';
 215
 216         /** @var float Guess of how many seconds it takes to replicate a small insert */
 217         private static $TINY_WRITE_SEC = 0.010;
 218         /** @var float Consider a write slow if it took more than this many seconds */
 219         private static $SLOW_WRITE_SEC = 0.500;
 220         /** @var float Assume an insert of this many rows or less should be fast to replicate */
 221         private static $SMALL_WRITE_ROWS = 100;
 222
 223         /** @var string[] List of DBO_* flags that can be changed after connection */
 224         protected static $MUTABLE_FLAGS = [
 225                 'DBO_DEBUG',
 226                 'DBO_NOBUFFER',
 227                 'DBO_TRX',
 228                 'DBO_DDLMODE',
 229         ];
 230         /** @var int Bit field of all DBO_* flags that can be changed after connection */
 231         protected static $DBO_MUTABLE = (
 232                 self::DBO_DEBUG | self::DBO_NOBUFFER | self::DBO_TRX | self::DBO_DDLMODE
 233         );
 234
 235         /**
 236          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 237          * @param array $params Parameters passed from Database::factory()
 238          */
 239         public function __construct( array $params ) {
 240                 $this->connectionParams = [];
 241                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 242                         $this->connectionParams[$name] = $params[$name];
 243                 }
 244                 $this->connectionVariables = $params['variables'] ?? [];
 245                 $this->cliMode = $params['cliMode'];
 246                 $this->agent = $params['agent'];
 247                 $this->flags = $params['flags'];
 248                 if ( $this->flags & self::DBO_DEFAULT ) {
 249                         if ( $this->cliMode ) {
 250                                 $this->flags &= ~self::DBO_TRX;
 251                         } else {
 252                                 $this->flags |= self::DBO_TRX;
 253                         }
 254                 }
 255                 $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'] ?? 10000;
 256
 257                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 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                 // Set initial dummy domain until open() sets the final DB/prefix
 266                 $this->currentDomain = new DatabaseDomain(
 267                         $params['dbname'] != '' ? $params['dbname'] : null,
 268                         $params['schema'] != '' ? $params['schema'] : null,
 269                         $params['tablePrefix']
 270                 );
 271         }
 272
 273         /**
 274          * Initialize the connection to the database over the wire (or to local files)
 275          *
 276          * @throws LogicException
 277          * @throws InvalidArgumentException
 278          * @throws DBConnectionError
 279          * @since 1.31
 280          */
 281         final public function initConnection() {
 282                 if ( $this->isOpen() ) {
 283                         throw new LogicException( __METHOD__ . ': already connected' );
 284                 }
 285                 // Establish the connection
 286                 $this->doInitConnection();
 287         }
 288
 289         /**
 290          * Actually connect to the database over the wire (or to local files)
 291          *
 292          * @throws DBConnectionError
 293          * @since 1.31
 294          */
 295         protected function doInitConnection() {
 296                 $this->open(
 297                         $this->connectionParams['host'],
 298                         $this->connectionParams['user'],
 299                         $this->connectionParams['password'],
 300                         $this->connectionParams['dbname'],
 301                         $this->connectionParams['schema'],
 302                         $this->connectionParams['tablePrefix']
 303                 );
 304         }
 305
 306         /**
 307          * Open a new connection to the database (closing any existing one)
 308          *
 309          * @param string|null $server Database server host
 310          * @param string|null $user Database user name
 311          * @param string|null $password Database user password
 312          * @param string|null $dbName Database name
 313          * @param string|null $schema Database schema name
 314          * @param string $tablePrefix Table prefix
 315          * @throws DBConnectionError
 316          */
 317         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 318
 319         /**
 320          * Construct a Database subclass instance given a database type and parameters
 321          *
 322          * This also connects to the database immediately upon object construction
 323          *
 324          * @param string $type A possible DB type (sqlite, mysql, postgres,...)
 325          * @param array $params Parameter map with keys:
 326          *   - host : The hostname of the DB server
 327          *   - user : The name of the database user the client operates under
 328          *   - password : The password for the database user
 329          *   - dbname : The name of the database to use where queries do not specify one.
 330          *      The database must exist or an error might be thrown. Setting this to the empty string
 331          *      will avoid any such errors and make the handle have no implicit database scope. This is
 332          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 333          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 334          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 335          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 336          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 337          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 338          *      recognized in queries. This can be used in place of schemas for handle site farms.
 339          *   - flags : Optional bit field of DBO_* constants that define connection, protocol,
 340          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 341          *      flag in place UNLESS this this database simply acts as a key/value store.
 342          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 343          *      'mysqli' driver; the old one 'mysql' has been removed.
 344          *   - variables: Optional map of session variables to set after connecting. This can be
 345          *      used to adjust lock timeouts or encoding modes and the like.
 346          *   - connLogger: Optional PSR-3 logger interface instance.
 347          *   - queryLogger: Optional PSR-3 logger interface instance.
 348          *   - profiler : Optional callback that takes a section name argument and returns
 349          *      a ScopedCallback instance that ends the profile section in its destructor.
 350          *      These will be called in query(), using a simplified version of the SQL that
 351          *      also includes the agent as a SQL comment.
 352          *   - trxProfiler: Optional TransactionProfiler instance.
 353          *   - errorLogger: Optional callback that takes an Exception and logs it.
 354          *   - deprecationLogger: Optional callback that takes a string and logs it.
 355          *   - cliMode: Whether to consider the execution context that of a CLI script.
 356          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 357          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 358          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 359          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 360          * @return Database|null If the database driver or extension cannot be found
 361          * @throws InvalidArgumentException If the database driver or extension cannot be found
 362          * @since 1.18
 363          */
 364         final public static function factory( $type, $params = [], $connect = self::NEW_CONNECTED ) {
 365                 $class = self::getClass( $type, $params['driver'] ?? null );
 366
 367                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 368                         $params += [
 369                                 'host' => null,
 370                                 'user' => null,
 371                                 'password' => null,
 372                                 'dbname' => null,
 373                                 'schema' => null,
 374                                 'tablePrefix' => '',
 375                                 'flags' => 0,
 376                                 'variables' => [],
 377                                 'cliMode' => ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' ),
 378                                 'agent' => basename( $_SERVER['SCRIPT_NAME'] ) . '@' . gethostname()
 379                         ];
 380
 381                         $normalizedParams = [
 382                                 // Configuration
 383                                 'host' => strlen( $params['host'] ) ? $params['host'] : null,
 384                                 'user' => strlen( $params['user'] ) ? $params['user'] : null,
 385                                 'password' => is_string( $params['password'] ) ? $params['password'] : null,
 386                                 'dbname' => strlen( $params['dbname'] ) ? $params['dbname'] : null,
 387                                 'schema' => strlen( $params['schema'] ) ? $params['schema'] : null,
 388                                 'tablePrefix' => (string)$params['tablePrefix'],
 389                                 'flags' => (int)$params['flags'],
 390                                 'variables' => $params['variables'],
 391                                 'cliMode' => (bool)$params['cliMode'],
 392                                 'agent' => (string)$params['agent'],
 393                                 // Objects and callbacks
 394                                 'srvCache' => $params['srvCache'] ?? new HashBagOStuff(),
 395                                 'profiler' => $params['profiler'] ?? null,
 396                                 'trxProfiler' => $params['trxProfiler'] ?? new TransactionProfiler(),
 397                                 'connLogger' => $params['connLogger'] ?? new NullLogger(),
 398                                 'queryLogger' => $params['queryLogger'] ?? new NullLogger(),
 399                                 'errorLogger' => $params['errorLogger'] ?? function ( Exception $e ) {
 400                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 401                                 },
 402                                 'deprecationLogger' => $params['deprecationLogger'] ?? function ( $msg ) {
 403                                         trigger_error( $msg, E_USER_DEPRECATED );
 404                                 }
 405                         ] + $params;
 406
 407                         /** @var Database $conn */
 408                         $conn = new $class( $normalizedParams );
 409                         if ( $connect === self::NEW_CONNECTED ) {
 410                                 $conn->initConnection();
 411                         }
 412                 } else {
 413                         $conn = null;
 414                 }
 415
 416                 return $conn;
 417         }
 418
 419         /**
 420          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 421          * @param string|null $driver Optional name of a specific DB client driver
 422          * @return array Map of (Database::ATTR_* constant => value) for all such constants
 423          * @throws InvalidArgumentException
 424          * @since 1.31
 425          */
 426         final public static function attributesFromType( $dbType, $driver = null ) {
 427                 static $defaults = [
 428                         self::ATTR_DB_LEVEL_LOCKING => false,
 429                         self::ATTR_SCHEMAS_AS_TABLE_GROUPS => false
 430                 ];
 431
 432                 $class = self::getClass( $dbType, $driver );
 433
 434                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 435         }
 436
 437         /**
 438          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 439          * @param string|null $driver Optional name of a specific DB client driver
 440          * @return string Database subclass name to use
 441          * @throws InvalidArgumentException
 442          */
 443         private static function getClass( $dbType, $driver = null ) {
 444                 // For database types with built-in support, the below maps type to IDatabase
 445                 // implementations. For types with multipe driver implementations (PHP extensions),
 446                 // an array can be used, keyed by extension name. In case of an array, the
 447                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 448                 // we auto-detect the first available driver. For types without built-in support,
 449                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 450                 static $builtinTypes = [
 451                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 452                         'sqlite' => DatabaseSqlite::class,
 453                         'postgres' => DatabasePostgres::class,
 454                 ];
 455
 456                 $dbType = strtolower( $dbType );
 457                 $class = false;
 458
 459                 if ( isset( $builtinTypes[$dbType] ) ) {
 460                         $possibleDrivers = $builtinTypes[$dbType];
 461                         if ( is_string( $possibleDrivers ) ) {
 462                                 $class = $possibleDrivers;
 463                         } elseif ( (string)$driver !== '' ) {
 464                                 if ( !isset( $possibleDrivers[$driver] ) ) {
 465                                         throw new InvalidArgumentException( __METHOD__ .
 466                                                 " type '$dbType' does not support driver '{$driver}'" );
 467                                 }
 468
 469                                 $class = $possibleDrivers[$driver];
 470                         } else {
 471                                 foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 472                                         if ( extension_loaded( $posDriver ) ) {
 473                                                 $class = $possibleClass;
 474                                                 break;
 475                                         }
 476                                 }
 477                         }
 478                 } else {
 479                         $class = 'Database' . ucfirst( $dbType );
 480                 }
 481
 482                 if ( $class === false ) {
 483                         throw new InvalidArgumentException( __METHOD__ .
 484                                 " no viable database extension found for type '$dbType'" );
 485                 }
 486
 487                 return $class;
 488         }
 489
 490         /**
 491          * @return array Map of (Database::ATTR_* constant => value)
 492          * @since 1.31
 493          */
 494         protected static function getAttributes() {
 495                 return [];
 496         }
 497
 498         /**
 499          * Set the PSR-3 logger interface to use for query logging. (The logger
 500          * interfaces for connection logging and error logging can be set with the
 501          * constructor.)
 502          *
 503          * @param LoggerInterface $logger
 504          */
 505         public function setLogger( LoggerInterface $logger ) {
 506                 $this->queryLogger = $logger;
 507         }
 508
 509         public function getServerInfo() {
 510                 return $this->getServerVersion();
 511         }
 512
 513         /**
 514          * Backwards-compatibility no-op method for disabling query buffering
 515          *
 516          * @param null|bool $buffer Whether to buffer queries (ignored)
 517          * @return bool Whether buffering was already enabled (always true)
 518          * @deprecated Since 1.34 Use query batching; this no longer does anything
 519          */
 520         public function bufferResults( $buffer = null ) {
 521                 return true;
 522         }
 523
 524         final public function trxLevel() {
 525                 return ( $this->trxShortId != '' ) ? 1 : 0;
 526         }
 527
 528         public function trxTimestamp() {
 529                 return $this->trxLevel() ? $this->trxTimestamp : null;
 530         }
 531
 532         /**
 533          * @return int One of the STATUS_TRX_* class constants
 534          * @since 1.31
 535          */
 536         public function trxStatus() {
 537                 return $this->trxStatus;
 538         }
 539
 540         public function tablePrefix( $prefix = null ) {
 541                 $old = $this->currentDomain->getTablePrefix();
 542                 if ( $prefix !== null ) {
 543                         $this->currentDomain = new DatabaseDomain(
 544                                 $this->currentDomain->getDatabase(),
 545                                 $this->currentDomain->getSchema(),
 546                                 $prefix
 547                         );
 548                 }
 549
 550                 return $old;
 551         }
 552
 553         public function dbSchema( $schema = null ) {
 554                 if ( strlen( $schema ) && $this->getDBname() === null ) {
 555                         throw new DBUnexpectedError( $this, "Cannot set schema to '$schema'; no database set" );
 556                 }
 557
 558                 $old = $this->currentDomain->getSchema();
 559                 if ( $schema !== null ) {
 560                         $this->currentDomain = new DatabaseDomain(
 561                                 $this->currentDomain->getDatabase(),
 562                                 // DatabaseDomain uses null for unspecified schemas
 563                                 strlen( $schema ) ? $schema : null,
 564                                 $this->currentDomain->getTablePrefix()
 565                         );
 566                 }
 567
 568                 return (string)$old;
 569         }
 570
 571         /**
 572          * @return string Schema to use to qualify relations in queries
 573          */
 574         protected function relationSchemaQualifier() {
 575                 return $this->dbSchema();
 576         }
 577
 578         public function getLBInfo( $name = null ) {
 579                 if ( is_null( $name ) ) {
 580                         return $this->lbInfo;
 581                 }
 582
 583                 if ( array_key_exists( $name, $this->lbInfo ) ) {
 584                         return $this->lbInfo[$name];
 585                 }
 586
 587                 return null;
 588         }
 589
 590         public function setLBInfo( $nameOrArray, $value = null ) {
 591                 if ( is_array( $nameOrArray ) ) {
 592                         $this->lbInfo = $nameOrArray;
 593                 } elseif ( is_string( $nameOrArray ) ) {
 594                         if ( $value !== null ) {
 595                                 $this->lbInfo[$nameOrArray] = $value;
 596                         } else {
 597                                 unset( $this->lbInfo[$nameOrArray] );
 598                         }
 599                 } else {
 600                         throw new InvalidArgumentException( "Got non-string key" );
 601                 }
 602         }
 603
 604         public function setLazyMasterHandle( IDatabase $conn ) {
 605                 $this->lazyMasterHandle = $conn;
 606         }
 607
 608         /**
 609          * @return IDatabase|null
 610          * @see setLazyMasterHandle()
 611          * @since 1.27
 612          */
 613         protected function getLazyMasterHandle() {
 614                 return $this->lazyMasterHandle;
 615         }
 616
 617         public function implicitOrderby() {
 618                 return true;
 619         }
 620
 621         public function lastQuery() {
 622                 return $this->lastQuery;
 623         }
 624
 625         public function lastDoneWrites() {
 626                 return $this->lastWriteTime ?: false;
 627         }
 628
 629         public function writesPending() {
 630                 return $this->trxLevel() && $this->trxDoneWrites;
 631         }
 632
 633         public function writesOrCallbacksPending() {
 634                 return $this->trxLevel() && (
 635                         $this->trxDoneWrites ||
 636                         $this->trxIdleCallbacks ||
 637                         $this->trxPreCommitCallbacks ||
 638                         $this->trxEndCallbacks ||
 639                         $this->trxSectionCancelCallbacks
 640                 );
 641         }
 642
 643         public function preCommitCallbacksPending() {
 644                 return $this->trxLevel() && $this->trxPreCommitCallbacks;
 645         }
 646
 647         /**
 648          * @return string|null
 649          */
 650         final protected function getTransactionRoundId() {
 651                 // If transaction round participation is enabled, see if one is active
 652                 if ( $this->getFlag( self::DBO_TRX ) ) {
 653                         $id = $this->getLBInfo( 'trxRoundId' );
 654
 655                         return is_string( $id ) ? $id : null;
 656                 }
 657
 658                 return null;
 659         }
 660
 661         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 662                 if ( !$this->trxLevel() ) {
 663                         return false;
 664                 } elseif ( !$this->trxDoneWrites ) {
 665                         return 0.0;
 666                 }
 667
 668                 switch ( $type ) {
 669                         case self::ESTIMATE_DB_APPLY:
 670                                 return $this->pingAndCalculateLastTrxApplyTime();
 671                         default: // everything
 672                                 return $this->trxWriteDuration;
 673                 }
 674         }
 675
 676         /**
 677          * @return float Time to apply writes to replicas based on trxWrite* fields
 678          */
 679         private function pingAndCalculateLastTrxApplyTime() {
 680                 $this->ping( $rtt );
 681
 682                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 683                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 684                 // For omitted queries, make them count as something at least
 685                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 686                 $applyTime += self::$TINY_WRITE_SEC * $omitted;
 687
 688                 return $applyTime;
 689         }
 690
 691         public function pendingWriteCallers() {
 692                 return $this->trxLevel() ? $this->trxWriteCallers : [];
 693         }
 694
 695         public function pendingWriteRowsAffected() {
 696                 return $this->trxWriteAffectedRows;
 697         }
 698
 699         /**
 700          * List the methods that have write queries or callbacks for the current transaction
 701          *
 702          * This method should not be used outside of Database/LoadBalancer
 703          *
 704          * @return string[]
 705          * @since 1.32
 706          */
 707         public function pendingWriteAndCallbackCallers() {
 708                 $fnames = $this->pendingWriteCallers();
 709                 foreach ( [
 710                         $this->trxIdleCallbacks,
 711                         $this->trxPreCommitCallbacks,
 712                         $this->trxEndCallbacks,
 713                         $this->trxSectionCancelCallbacks
 714                 ] as $callbacks ) {
 715                         foreach ( $callbacks as $callback ) {
 716                                 $fnames[] = $callback[1];
 717                         }
 718                 }
 719
 720                 return $fnames;
 721         }
 722
 723         /**
 724          * @return string
 725          */
 726         private function flatAtomicSectionList() {
 727                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 728                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 729                 } );
 730         }
 731
 732         public function isOpen() {
 733                 return (bool)$this->conn;
 734         }
 735
 736         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 737                 if ( $flag & ~static::$DBO_MUTABLE ) {
 738                         throw new DBUnexpectedError(
 739                                 $this,
 740                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 741                         );
 742                 }
 743
 744                 if ( $remember === self::REMEMBER_PRIOR ) {
 745                         array_push( $this->priorFlags, $this->flags );
 746                 }
 747
 748                 $this->flags |= $flag;
 749         }
 750
 751         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 752                 if ( $flag & ~static::$DBO_MUTABLE ) {
 753                         throw new DBUnexpectedError(
 754                                 $this,
 755                                 "Got $flag (allowed: " . implode( ', ', static::$MUTABLE_FLAGS ) . ')'
 756                         );
 757                 }
 758
 759                 if ( $remember === self::REMEMBER_PRIOR ) {
 760                         array_push( $this->priorFlags, $this->flags );
 761                 }
 762
 763                 $this->flags &= ~$flag;
 764         }
 765
 766         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 767                 if ( !$this->priorFlags ) {
 768                         return;
 769                 }
 770
 771                 if ( $state === self::RESTORE_INITIAL ) {
 772                         $this->flags = reset( $this->priorFlags );
 773                         $this->priorFlags = [];
 774                 } else {
 775                         $this->flags = array_pop( $this->priorFlags );
 776                 }
 777         }
 778
 779         public function getFlag( $flag ) {
 780                 return ( ( $this->flags & $flag ) === $flag );
 781         }
 782
 783         public function getDomainID() {
 784                 return $this->currentDomain->getId();
 785         }
 786
 787         /**
 788          * Get information about an index into an object
 789          * @param string $table Table name
 790          * @param string $index Index name
 791          * @param string $fname Calling function name
 792          * @return mixed Database-specific index description class or false if the index does not exist
 793          */
 794         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 795
 796         /**
 797          * Wrapper for addslashes()
 798          *
 799          * @param string $s String to be slashed.
 800          * @return string Slashed string.
 801          */
 802         abstract function strencode( $s );
 803
 804         /**
 805          * Set a custom error handler for logging errors during database connection
 806          */
 807         protected function installErrorHandler() {
 808                 $this->lastPhpError = false;
 809                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 810                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 811         }
 812
 813         /**
 814          * Restore the previous error handler and return the last PHP error for this DB
 815          *
 816          * @return bool|string
 817          */
 818         protected function restoreErrorHandler() {
 819                 restore_error_handler();
 820                 if ( $this->htmlErrors !== false ) {
 821                         ini_set( 'html_errors', $this->htmlErrors );
 822                 }
 823
 824                 return $this->getLastPHPError();
 825         }
 826
 827         /**
 828          * @return string|bool Last PHP error for this DB (typically connection errors)
 829          */
 830         protected function getLastPHPError() {
 831                 if ( $this->lastPhpError ) {
 832                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->lastPhpError );
 833                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 834
 835                         return $error;
 836                 }
 837
 838                 return false;
 839         }
 840
 841         /**
 842          * Error handler for logging errors during database connection
 843          * This method should not be used outside of Database classes
 844          *
 845          * @param int $errno
 846          * @param string $errstr
 847          */
 848         public function connectionErrorLogger( $errno, $errstr ) {
 849                 $this->lastPhpError = $errstr;
 850         }
 851
 852         /**
 853          * Create a log context to pass to PSR-3 logger functions.
 854          *
 855          * @param array $extras Additional data to add to context
 856          * @return array
 857          */
 858         protected function getLogContext( array $extras = [] ) {
 859                 return array_merge(
 860                         [
 861                                 'db_server' => $this->server,
 862                                 'db_name' => $this->getDBname(),
 863                                 'db_user' => $this->user,
 864                         ],
 865                         $extras
 866                 );
 867         }
 868
 869         final public function close() {
 870                 $exception = null; // error to throw after disconnecting
 871
 872                 $wasOpen = (bool)$this->conn;
 873                 // This should mostly do nothing if the connection is already closed
 874                 if ( $this->conn ) {
 875                         // Roll back any dangling transaction first
 876                         if ( $this->trxLevel() ) {
 877                                 if ( $this->trxAtomicLevels ) {
 878                                         // Cannot let incomplete atomic sections be committed
 879                                         $levels = $this->flatAtomicSectionList();
 880                                         $exception = new DBUnexpectedError(
 881                                                 $this,
 882                                                 __METHOD__ . ": atomic sections $levels are still open"
 883                                         );
 884                                 } elseif ( $this->trxAutomatic ) {
 885                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 886                                         // (empty ones we can silently roll back)
 887                                         if ( $this->writesOrCallbacksPending() ) {
 888                                                 $exception = new DBUnexpectedError(
 889                                                         $this,
 890                                                         __METHOD__ .
 891                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)"
 892                                                 );
 893                                         }
 894                                 } else {
 895                                         // Manual transactions should have been committed or rolled
 896                                         // back, even if empty.
 897                                         $exception = new DBUnexpectedError(
 898                                                 $this,
 899                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})"
 900                                         );
 901                                 }
 902
 903                                 if ( $this->trxEndCallbacksSuppressed ) {
 904                                         $exception = $exception ?: new DBUnexpectedError(
 905                                                 $this,
 906                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit'
 907                                         );
 908                                 }
 909
 910                                 // Rollback the changes and run any callbacks as needed
 911                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 912                         }
 913
 914                         // Close the actual connection in the binding handle
 915                         $closed = $this->closeConnection();
 916                 } else {
 917                         $closed = true; // already closed; nothing to do
 918                 }
 919
 920                 $this->conn = null;
 921
 922                 // Throw any unexpected errors after having disconnected
 923                 if ( $exception instanceof Exception ) {
 924                         throw $exception;
 925                 }
 926
 927                 // Note that various subclasses call close() at the start of open(), which itself is
 928                 // called by replaceLostConnection(). In that case, just because onTransactionResolution()
 929                 // callbacks are pending does not mean that an exception should be thrown. Rather, they
 930                 // will be executed after the reconnection step.
 931                 if ( $wasOpen ) {
 932                         // Sanity check that no callbacks are dangling
 933                         $fnames = $this->pendingWriteAndCallbackCallers();
 934                         if ( $fnames ) {
 935                                 throw new RuntimeException(
 936                                         "Transaction callbacks are still pending: " . implode( ', ', $fnames )
 937                                 );
 938                         }
 939                 }
 940
 941                 return $closed;
 942         }
 943
 944         /**
 945          * Make sure there is an open connection handle (alive or not) as a sanity check
 946          *
 947          * This guards against fatal errors to the binding handle not being defined
 948          * in cases where open() was never called or close() was already called
 949          *
 950          * @throws DBUnexpectedError
 951          */
 952         final protected function assertHasConnectionHandle() {
 953                 if ( !$this->isOpen() ) {
 954                         throw new DBUnexpectedError( $this, "DB connection was already closed" );
 955                 }
 956         }
 957
 958         /**
 959          * Make sure that this server is not marked as a replica nor read-only as a sanity check
 960          *
 961          * @throws DBReadOnlyRoleError
 962          * @throws DBReadOnlyError
 963          */
 964         protected function assertIsWritableMaster() {
 965                 if ( $this->getLBInfo( 'replica' ) ) {
 966                         throw new DBReadOnlyRoleError(
 967                                 $this,
 968                                 'Write operations are not allowed on replica database connections'
 969                         );
 970                 }
 971                 $reason = $this->getReadOnlyReason();
 972                 if ( $reason !== false ) {
 973                         throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 974                 }
 975         }
 976
 977         /**
 978          * Closes underlying database connection
 979          * @since 1.20
 980          * @return bool Whether connection was closed successfully
 981          */
 982         abstract protected function closeConnection();
 983
 984         /**
 985          * Run a query and return a DBMS-dependent wrapper or boolean
 986          *
 987          * This is meant to handle the basic command of actually sending a query to the
 988          * server via the driver. No implicit transaction, reconnection, nor retry logic
 989          * should happen here. The higher level query() method is designed to handle those
 990          * sorts of concerns. This method should not trigger such higher level methods.
 991          *
 992          * The lastError() and lastErrno() methods should meaningfully reflect what error,
 993          * if any, occured during the last call to this method. Methods like executeQuery(),
 994          * query(), select(), insert(), update(), delete(), and upsert() implement their calls
 995          * to doQuery() such that an immediately subsequent call to lastError()/lastErrno()
 996          * meaningfully reflects any error that occured during that public query method call.
 997          *
 998          * For SELECT queries, this returns either:
 999          *   - a) A driver-specific value/resource, only on success. This can be iterated
1000          *        over by calling fetchObject()/fetchRow() until there are no more rows.
1001          *        Alternatively, the result can be passed to resultObject() to obtain an
1002          *        IResultWrapper instance which can then be iterated over via "foreach".
1003          *   - b) False, on any query failure
1004          *
1005          * For non-SELECT queries, this returns either:
1006          *   - a) A driver-specific value/resource, only on success
1007          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1008          *   - c) False, on any query failure
1009          *
1010          * @param string $sql SQL query
1011          * @return mixed|bool An object, resource, or true on success; false on failure
1012          */
1013         abstract protected function doQuery( $sql );
1014
1015         /**
1016          * Determine whether a query writes to the DB. When in doubt, this returns true.
1017          *
1018          * Main use cases:
1019          *
1020          * - Subsequent web requests should not need to wait for replication from
1021          *   the master position seen by this web request, unless this request made
1022          *   changes to the master. This is handled by ChronologyProtector by checking
1023          *   doneWrites() at the end of the request. doneWrites() returns true if any
1024          *   query set lastWriteTime; which query() does based on isWriteQuery().
1025          *
1026          * - Reject write queries to replica DBs, in query().
1027          *
1028          * @param string $sql
1029          * @return bool
1030          */
1031         protected function isWriteQuery( $sql ) {
1032                 // BEGIN and COMMIT queries are considered read queries here.
1033                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1034                 // treat these as write queries, in that their results have "affected rows"
1035                 // as meta data as from writes, instead of "num rows" as from reads.
1036                 // But, we treat them as read queries because when reading data (from
1037                 // either replica or master) we use transactions to enable repeatable-read
1038                 // snapshots, which ensures we get consistent results from the same snapshot
1039                 // for all queries within a request. Use cases:
1040                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1041                 // - We use this method to reject writes to replicas, but we need to allow
1042                 //   use of transactions on replicas for read snapshots. This is fine given
1043                 //   that transactions by themselves don't make changes, only actual writes
1044                 //   within the transaction matter, which we still detect.
1045                 return !preg_match(
1046                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|USE|\(SELECT)\b/i',
1047                         $sql
1048                 );
1049         }
1050
1051         /**
1052          * @param string $sql
1053          * @return string|null
1054          */
1055         protected function getQueryVerb( $sql ) {
1056                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1057         }
1058
1059         /**
1060          * Determine whether a SQL statement is sensitive to isolation level.
1061          *
1062          * A SQL statement is considered transactable if its result could vary
1063          * depending on the transaction isolation level. Operational commands
1064          * such as 'SET' and 'SHOW' are not considered to be transactable.
1065          *
1066          * Main purpose: Used by query() to decide whether to begin a transaction
1067          * before the current query (in DBO_TRX mode, on by default).
1068          *
1069          * @param string $sql
1070          * @return bool
1071          */
1072         protected function isTransactableQuery( $sql ) {
1073                 return !in_array(
1074                         $this->getQueryVerb( $sql ),
1075                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER', 'USE', 'SHOW' ],
1076                         true
1077                 );
1078         }
1079
1080         /**
1081          * @param string $sql A SQL query
1082          * @param bool $pseudoPermanent Treat any table from CREATE TEMPORARY as pseudo-permanent
1083          * @return array A n-tuple of:
1084          *   - int|null: A self::TEMP_* constant for temp table operations or null otherwise
1085          *   - string|null: The name of the new temporary table $sql creates, or null
1086          *   - string|null: The name of the temporary table that $sql drops, or null
1087          */
1088         protected function getTempWrites( $sql, $pseudoPermanent ) {
1089                 static $qt = '[`"\']?(\w+)[`"\']?'; // quoted table
1090
1091                 if ( preg_match(
1092                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?' . $qt . '/i',
1093                         $sql,
1094                         $matches
1095                 ) ) {
1096                         $type = $pseudoPermanent ? self::$TEMP_PSEUDO_PERMANENT : self::$TEMP_NORMAL;
1097
1098                         return [ $type, $matches[1], null ];
1099                 } elseif ( preg_match(
1100                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1101                         $sql,
1102                         $matches
1103                 ) ) {
1104                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, $matches[1] ];
1105                 } elseif ( preg_match(
1106                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?' . $qt . '/i',
1107                         $sql,
1108                         $matches
1109                 ) ) {
1110                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1111                 } elseif ( preg_match(
1112                         '/^(?:(?:INSERT|REPLACE)\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+' . $qt . '/i',
1113                         $sql,
1114                         $matches
1115                 ) ) {
1116                         return [ $this->sessionTempTables[$matches[1]] ?? null, null, null ];
1117                 }
1118
1119                 return [ null, null, null ];
1120         }
1121
1122         /**
1123          * @param IResultWrapper|bool $ret
1124          * @param int|null $tmpType TEMP_NORMAL or TEMP_PSEUDO_PERMANENT
1125          * @param string|null $tmpNew Name of created temp table
1126          * @param string|null $tmpDel Name of dropped temp table
1127          */
1128         protected function registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel ) {
1129                 if ( $ret !== false ) {
1130                         if ( $tmpNew !== null ) {
1131                                 $this->sessionTempTables[$tmpNew] = $tmpType;
1132                         }
1133                         if ( $tmpDel !== null ) {
1134                                 unset( $this->sessionTempTables[$tmpDel] );
1135                         }
1136                 }
1137         }
1138
1139         public function query( $sql, $fname = __METHOD__, $flags = 0 ) {
1140                 $flags = (int)$flags; // b/c; this field used to be a bool
1141                 // Sanity check that the SQL query is appropriate in the current context and is
1142                 // allowed for an outside caller (e.g. does not break transaction/session tracking).
1143                 $this->assertQueryIsCurrentlyAllowed( $sql, $fname );
1144
1145                 // Send the query to the server and fetch any corresponding errors
1146                 list( $ret, $err, $errno, $unignorable ) = $this->executeQuery( $sql, $fname, $flags );
1147                 if ( $ret === false ) {
1148                         $ignoreErrors = $this->fieldHasBit( $flags, self::QUERY_SILENCE_ERRORS );
1149                         // Throw an error unless both the ignore flag was set and a rollback is not needed
1150                         $this->reportQueryError( $err, $errno, $sql, $fname, $ignoreErrors && !$unignorable );
1151                 }
1152
1153                 return $this->resultObject( $ret );
1154         }
1155
1156         /**
1157          * Execute a query, retrying it if there is a recoverable connection loss
1158          *
1159          * This is similar to query() except:
1160          *   - It does not prevent all non-ROLLBACK queries if there is a corrupted transaction
1161          *   - It does not disallow raw queries that are supposed to use dedicated IDatabase methods
1162          *   - It does not throw exceptions for common error cases
1163          *
1164          * This is meant for internal use with Database subclasses.
1165          *
1166          * @param string $sql Original SQL query
1167          * @param string $fname Name of the calling function
1168          * @param int $flags Bit field of class QUERY_* constants
1169          * @return array An n-tuple of:
1170          *   - mixed|bool: An object, resource, or true on success; false on failure
1171          *   - string: The result of calling lastError()
1172          *   - int: The result of calling lastErrno()
1173          *   - bool: Whether a rollback is needed to allow future non-rollback queries
1174          * @throws DBUnexpectedError
1175          */
1176         final protected function executeQuery( $sql, $fname, $flags ) {
1177                 $this->assertHasConnectionHandle();
1178
1179                 $priorTransaction = $this->trxLevel();
1180
1181                 if ( $this->isWriteQuery( $sql ) ) {
1182                         // In theory, non-persistent writes are allowed in read-only mode, but due to things
1183                         // like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1184                         $this->assertIsWritableMaster();
1185                         // Do not treat temporary table writes as "meaningful writes" since they are only
1186                         // visible to one session and are not permanent. Profile them as reads. Integration
1187                         // tests can override this behavior via $flags.
1188                         $pseudoPermanent = $this->fieldHasBit( $flags, self::QUERY_PSEUDO_PERMANENT );
1189                         list( $tmpType, $tmpNew, $tmpDel ) = $this->getTempWrites( $sql, $pseudoPermanent );
1190                         $isPermWrite = ( $tmpType !== self::$TEMP_NORMAL );
1191                         // DBConnRef uses QUERY_REPLICA_ROLE to enforce the replica role for raw SQL queries
1192                         if ( $isPermWrite && $this->fieldHasBit( $flags, self::QUERY_REPLICA_ROLE ) ) {
1193                                 throw new DBReadOnlyRoleError( $this, "Cannot write; target role is DB_REPLICA" );
1194                         }
1195                 } else {
1196                         // No permanent writes in this query
1197                         $isPermWrite = false;
1198                         // No temporary tables written to either
1199                         list( $tmpType, $tmpNew, $tmpDel ) = [ null, null, null ];
1200                 }
1201
1202                 // Add trace comment to the begin of the sql string, right after the operator.
1203                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598).
1204                 $encAgent = str_replace( '/', '-', $this->agent );
1205                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $encAgent */ ", $sql, 1 );
1206
1207                 // Send the query to the server and fetch any corresponding errors.
1208                 // This also doubles as a "ping" to see if the connection was dropped.
1209                 list( $ret, $err, $errno, $recoverableSR, $recoverableCL, $reconnected ) =
1210                         $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1211
1212                 // Check if the query failed due to a recoverable connection loss
1213                 $allowRetry = !$this->fieldHasBit( $flags, self::QUERY_NO_RETRY );
1214                 if ( $ret === false && $recoverableCL && $reconnected && $allowRetry ) {
1215                         // Silently resend the query to the server since it is safe and possible
1216                         list( $ret, $err, $errno, $recoverableSR, $recoverableCL ) =
1217                                 $this->executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags );
1218                 }
1219
1220                 // Register creation and dropping of temporary tables
1221                 $this->registerTempWrites( $ret, $tmpType, $tmpNew, $tmpDel );
1222
1223                 $corruptedTrx = false;
1224
1225                 if ( $ret === false ) {
1226                         if ( $priorTransaction ) {
1227                                 if ( $recoverableSR ) {
1228                                         # We're ignoring an error that caused just the current query to be aborted.
1229                                         # But log the cause so we can log a deprecation notice if a caller actually
1230                                         # does ignore it.
1231                                         $this->trxStatusIgnoredCause = [ $err, $errno, $fname ];
1232                                 } elseif ( !$recoverableCL ) {
1233                                         # Either the query was aborted or all queries after BEGIN where aborted.
1234                                         # In the first case, the only options going forward are (a) ROLLBACK, or
1235                                         # (b) ROLLBACK TO SAVEPOINT (if one was set). If the later case, the only
1236                                         # option is ROLLBACK, since the snapshots would have been released.
1237                                         $corruptedTrx = true; // cannot recover
1238                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1239                                         $this->trxStatusCause =
1240                                                 $this->getQueryExceptionAndLog( $err, $errno, $sql, $fname );
1241                                         $this->trxStatusIgnoredCause = null;
1242                                 }
1243                         }
1244                 }
1245
1246                 return [ $ret, $err, $errno, $corruptedTrx ];
1247         }
1248
1249         /**
1250          * Wrapper for doQuery() that handles DBO_TRX, profiling, logging, affected row count
1251          * tracking, and reconnects (without retry) on query failure due to connection loss
1252          *
1253          * @param string $sql Original SQL query
1254          * @param string $commentedSql SQL query with debugging/trace comment
1255          * @param bool $isPermWrite Whether the query is a (non-temporary table) write
1256          * @param string $fname Name of the calling function
1257          * @param int $flags Bit field of class QUERY_* constants
1258          * @return array An n-tuple of:
1259          *   - mixed|bool: An object, resource, or true on success; false on failure
1260          *   - string: The result of calling lastError()
1261          *   - int: The result of calling lastErrno()
1262          *       - bool: Whether a statement rollback error occured
1263          *   - bool: Whether a disconnect *both* happened *and* was recoverable
1264          *   - bool: Whether a reconnection attempt was *both* made *and* succeeded
1265          * @throws DBUnexpectedError
1266          */
1267         private function executeQueryAttempt( $sql, $commentedSql, $isPermWrite, $fname, $flags ) {
1268                 $priorWritesPending = $this->writesOrCallbacksPending();
1269
1270                 if ( ( $flags & self::QUERY_IGNORE_DBO_TRX ) == 0 ) {
1271                         $this->beginIfImplied( $sql, $fname );
1272                 }
1273
1274                 // Keep track of whether the transaction has write queries pending
1275                 if ( $isPermWrite ) {
1276                         $this->lastWriteTime = microtime( true );
1277                         if ( $this->trxLevel() && !$this->trxDoneWrites ) {
1278                                 $this->trxDoneWrites = true;
1279                                 $this->trxProfiler->transactionWritingIn(
1280                                         $this->server, $this->getDomainID(), $this->trxShortId );
1281                         }
1282                 }
1283
1284                 $prefix = $this->getLBInfo( 'master' ) ? 'query-m: ' : 'query: ';
1285                 $generalizedSql = new GeneralizedSql( $sql, $this->trxShortId, $prefix );
1286
1287                 $startTime = microtime( true );
1288                 $ps = $this->profiler
1289                         ? ( $this->profiler )( $generalizedSql->stringify() )
1290                         : null;
1291                 $this->affectedRowCount = null;
1292                 $this->lastQuery = $sql;
1293                 $ret = $this->doQuery( $commentedSql );
1294                 $lastError = $this->lastError();
1295                 $lastErrno = $this->lastErrno();
1296
1297                 $this->affectedRowCount = $this->affectedRows();
1298                 unset( $ps ); // profile out (if set)
1299                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1300
1301                 $recoverableSR = false; // recoverable statement rollback?
1302                 $recoverableCL = false; // recoverable connection loss?
1303                 $reconnected = false; // reconnection both attempted and succeeded?
1304
1305                 if ( $ret !== false ) {
1306                         $this->lastPing = $startTime;
1307                         if ( $isPermWrite && $this->trxLevel() ) {
1308                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1309                                 $this->trxWriteCallers[] = $fname;
1310                         }
1311                 } elseif ( $this->wasConnectionError( $lastErrno ) ) {
1312                         # Check if no meaningful session state was lost
1313                         $recoverableCL = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1314                         # Update session state tracking and try to restore the connection
1315                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1316                 } else {
1317                         # Check if only the last query was rolled back
1318                         $recoverableSR = $this->wasKnownStatementRollbackError();
1319                 }
1320
1321                 if ( $sql === self::$PING_QUERY ) {
1322                         $this->lastRoundTripEstimate = $queryRuntime;
1323                 }
1324
1325                 $this->trxProfiler->recordQueryCompletion(
1326                         $generalizedSql,
1327                         $startTime,
1328                         $isPermWrite,
1329                         $isPermWrite ? $this->affectedRows() : $this->numRows( $ret )
1330                 );
1331
1332                 // Avoid the overhead of logging calls unless debug mode is enabled
1333                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1334                         $this->queryLogger->debug(
1335                                 "{method} [{runtime}s] {db_host}: $sql",
1336                                 [
1337                                         'method' => $fname,
1338                                         'db_host' => $this->getServer(),
1339                                         'domain' => $this->getDomainID(),
1340                                         'runtime' => round( $queryRuntime, 3 )
1341                                 ]
1342                         );
1343                 }
1344
1345                 return [ $ret, $lastError, $lastErrno, $recoverableSR, $recoverableCL, $reconnected ];
1346         }
1347
1348         /**
1349          * Start an implicit transaction if DBO_TRX is enabled and no transaction is active
1350          *
1351          * @param string $sql
1352          * @param string $fname
1353          */
1354         private function beginIfImplied( $sql, $fname ) {
1355                 if (
1356                         !$this->trxLevel() &&
1357                         $this->getFlag( self::DBO_TRX ) &&
1358                         $this->isTransactableQuery( $sql )
1359                 ) {
1360                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1361                         $this->trxAutomatic = true;
1362                 }
1363         }
1364
1365         /**
1366          * Update the estimated run-time of a query, not counting large row lock times
1367          *
1368          * LoadBalancer can be set to rollback transactions that will create huge replication
1369          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1370          * queries, like inserting a row can take a long time due to row locking. This method
1371          * uses some simple heuristics to discount those cases.
1372          *
1373          * @param string $sql A SQL write query
1374          * @param float $runtime Total runtime, including RTT
1375          * @param int $affected Affected row count
1376          */
1377         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1378                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1379                 $indicativeOfReplicaRuntime = true;
1380                 if ( $runtime > self::$SLOW_WRITE_SEC ) {
1381                         $verb = $this->getQueryVerb( $sql );
1382                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1383                         if ( $verb === 'INSERT' ) {
1384                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS;
1385                         } elseif ( $verb === 'REPLACE' ) {
1386                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::$SMALL_WRITE_ROWS / 2;
1387                         }
1388                 }
1389
1390                 $this->trxWriteDuration += $runtime;
1391                 $this->trxWriteQueryCount += 1;
1392                 $this->trxWriteAffectedRows += $affected;
1393                 if ( $indicativeOfReplicaRuntime ) {
1394                         $this->trxWriteAdjDuration += $runtime;
1395                         $this->trxWriteAdjQueryCount += 1;
1396                 }
1397         }
1398
1399         /**
1400          * Error out if the DB is not in a valid state for a query via query()
1401          *
1402          * @param string $sql
1403          * @param string $fname
1404          * @throws DBTransactionStateError
1405          */
1406         private function assertQueryIsCurrentlyAllowed( $sql, $fname ) {
1407                 $verb = $this->getQueryVerb( $sql );
1408                 if ( $verb === 'USE' ) {
1409                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead" );
1410                 }
1411
1412                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1413                         return;
1414                 }
1415
1416                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1417                         throw new DBTransactionStateError(
1418                                 $this,
1419                                 "Cannot execute query from $fname while transaction status is ERROR",
1420                                 [],
1421                                 $this->trxStatusCause
1422                         );
1423                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1424                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1425                         call_user_func( $this->deprecationLogger,
1426                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1427                                 "[$iLastErrno] $iLastError"
1428                         );
1429                         $this->trxStatusIgnoredCause = null;
1430                 }
1431         }
1432
1433         public function assertNoOpenTransactions() {
1434                 if ( $this->explicitTrxActive() ) {
1435                         throw new DBTransactionError(
1436                                 $this,
1437                                 "Explicit transaction still active. A caller may have caught an error. "
1438                                 . "Open transactions: " . $this->flatAtomicSectionList()
1439                         );
1440                 }
1441         }
1442
1443         /**
1444          * Determine whether it is safe to retry queries after a database connection is lost
1445          *
1446          * @param string $sql SQL query
1447          * @param bool $priorWritesPending Whether there is a transaction open with
1448          *     possible write queries or transaction pre-commit/idle callbacks
1449          *     waiting on it to finish.
1450          * @return bool True if it is safe to retry the query, false otherwise
1451          */
1452         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1453                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1454                 # Dropped connections also mean that named locks are automatically released.
1455                 # Only allow error suppression in autocommit mode or when the lost transaction
1456                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1457                 if ( $this->sessionNamedLocks ) {
1458                         return false; // possible critical section violation
1459                 } elseif ( $this->sessionTempTables ) {
1460                         return false; // tables might be queried latter
1461                 } elseif ( $sql === 'COMMIT' ) {
1462                         return !$priorWritesPending; // nothing written anyway? (T127428)
1463                 } elseif ( $sql === 'ROLLBACK' ) {
1464                         return true; // transaction lost...which is also what was requested :)
1465                 } elseif ( $this->explicitTrxActive() ) {
1466                         return false; // don't drop atomocity and explicit snapshots
1467                 } elseif ( $priorWritesPending ) {
1468                         return false; // prior writes lost from implicit transaction
1469                 }
1470
1471                 return true;
1472         }
1473
1474         /**
1475          * Clean things up after session (and thus transaction) loss before reconnect
1476          */
1477         private function handleSessionLossPreconnect() {
1478                 // Clean up tracking of session-level things...
1479                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1480                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1481                 $this->sessionTempTables = [];
1482                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1483                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1484                 $this->sessionNamedLocks = [];
1485                 // Session loss implies transaction loss
1486                 $oldTrxShortId = $this->consumeTrxShortId();
1487                 $this->trxAtomicCounter = 0;
1488                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1489                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1490                 // @note: leave trxRecurringCallbacks in place
1491                 if ( $this->trxDoneWrites ) {
1492                         $this->trxProfiler->transactionWritingOut(
1493                                 $this->server,
1494                                 $this->getDomainID(),
1495                                 $oldTrxShortId,
1496                                 $this->pendingWriteQueryDuration( self::ESTIMATE_TOTAL ),
1497                                 $this->trxWriteAffectedRows
1498                         );
1499                 }
1500         }
1501
1502         /**
1503          * Clean things up after session (and thus transaction) loss after reconnect
1504          */
1505         private function handleSessionLossPostconnect() {
1506                 try {
1507                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1508                         // If callback suppression is set then the array will remain unhandled.
1509                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1510                 } catch ( Exception $ex ) {
1511                         // Already logged; move on...
1512                 }
1513                 try {
1514                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1515                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1516                 } catch ( Exception $ex ) {
1517                         // Already logged; move on...
1518                 }
1519         }
1520
1521         /**
1522          * Reset the transaction ID and return the old one
1523          *
1524          * @return string The old transaction ID or the empty string if there wasn't one
1525          */
1526         private function consumeTrxShortId() {
1527                 $old = $this->trxShortId;
1528                 $this->trxShortId = '';
1529
1530                 return $old;
1531         }
1532
1533         /**
1534          * Checks whether the cause of the error is detected to be a timeout.
1535          *
1536          * It returns false by default, and not all engines support detecting this yet.
1537          * If this returns false, it will be treated as a generic query error.
1538          *
1539          * @param string $error Error text
1540          * @param int $errno Error number
1541          * @return bool
1542          */
1543         protected function wasQueryTimeout( $error, $errno ) {
1544                 return false;
1545         }
1546
1547         /**
1548          * Report a query error. Log the error, and if neither the object ignore
1549          * flag nor the $ignoreErrors flag is set, throw a DBQueryError.
1550          *
1551          * @param string $error
1552          * @param int $errno
1553          * @param string $sql
1554          * @param string $fname
1555          * @param bool $ignore
1556          * @throws DBQueryError
1557          */
1558         public function reportQueryError( $error, $errno, $sql, $fname, $ignore = false ) {
1559                 if ( $ignore ) {
1560                         $this->queryLogger->debug( "SQL ERROR (ignored): $error" );
1561                 } else {
1562                         throw $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1563                 }
1564         }
1565
1566         /**
1567          * @param string $error
1568          * @param string|int $errno
1569          * @param string $sql
1570          * @param string $fname
1571          * @return DBError
1572          */
1573         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1574                 $this->queryLogger->error(
1575                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1576                         $this->getLogContext( [
1577                                 'method' => __METHOD__,
1578                                 'errno' => $errno,
1579                                 'error' => $error,
1580                                 'sql1line' => mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 ),
1581                                 'fname' => $fname,
1582                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1583                         ] )
1584                 );
1585
1586                 if ( $this->wasQueryTimeout( $error, $errno ) ) {
1587                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1588                 } elseif ( $this->wasConnectionError( $errno ) ) {
1589                         $e = new DBQueryDisconnectedError( $this, $error, $errno, $sql, $fname );
1590                 } else {
1591                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1592                 }
1593
1594                 return $e;
1595         }
1596
1597         /**
1598          * @param string $error
1599          * @return DBConnectionError
1600          */
1601         final protected function newExceptionAfterConnectError( $error ) {
1602                 // Connection was not fully initialized and is not safe for use
1603                 $this->conn = null;
1604
1605                 $this->connLogger->error(
1606                         "Error connecting to {db_server} as user {db_user}: {error}",
1607                         $this->getLogContext( [
1608                                 'error' => $error,
1609                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1610                         ] )
1611                 );
1612
1613                 return new DBConnectionError( $this, $error );
1614         }
1615
1616         public function freeResult( $res ) {
1617         }
1618
1619         public function selectField(
1620                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1621         ) {
1622                 if ( $var === '*' ) { // sanity
1623                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1624                 }
1625
1626                 if ( !is_array( $options ) ) {
1627                         $options = [ $options ];
1628                 }
1629
1630                 $options['LIMIT'] = 1;
1631
1632                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1633                 if ( $res === false ) {
1634                         throw new DBUnexpectedError( $this, "Got false from select()" );
1635                 }
1636
1637                 $row = $this->fetchRow( $res );
1638                 if ( $row === false ) {
1639                         return false;
1640                 }
1641
1642                 return reset( $row );
1643         }
1644
1645         public function selectFieldValues(
1646                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1647         ) {
1648                 if ( $var === '*' ) { // sanity
1649                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1650                 } elseif ( !is_string( $var ) ) { // sanity
1651                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1652                 }
1653
1654                 if ( !is_array( $options ) ) {
1655                         $options = [ $options ];
1656                 }
1657
1658                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1659                 if ( $res === false ) {
1660                         throw new DBUnexpectedError( $this, "Got false from select()" );
1661                 }
1662
1663                 $values = [];
1664                 foreach ( $res as $row ) {
1665                         $values[] = $row->value;
1666                 }
1667
1668                 return $values;
1669         }
1670
1671         /**
1672          * Returns an optional USE INDEX clause to go after the table, and a
1673          * string to go at the end of the query.
1674          *
1675          * @param array $options Associative array of options to be turned into
1676          *   an SQL query, valid keys are listed in the function.
1677          * @return array
1678          * @see Database::select()
1679          */
1680         protected function makeSelectOptions( $options ) {
1681                 $preLimitTail = $postLimitTail = '';
1682                 $startOpts = '';
1683
1684                 $noKeyOptions = [];
1685
1686                 foreach ( $options as $key => $option ) {
1687                         if ( is_numeric( $key ) ) {
1688                                 $noKeyOptions[$option] = true;
1689                         }
1690                 }
1691
1692                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1693
1694                 $preLimitTail .= $this->makeOrderBy( $options );
1695
1696                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1697                         $postLimitTail .= ' FOR UPDATE';
1698                 }
1699
1700                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1701                         $postLimitTail .= ' LOCK IN SHARE MODE';
1702                 }
1703
1704                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1705                         $startOpts .= 'DISTINCT';
1706                 }
1707
1708                 # Various MySQL extensions
1709                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1710                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1711                 }
1712
1713                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1714                         $startOpts .= ' SQL_BIG_RESULT';
1715                 }
1716
1717                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1718                         $startOpts .= ' SQL_BUFFER_RESULT';
1719                 }
1720
1721                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1722                         $startOpts .= ' SQL_SMALL_RESULT';
1723                 }
1724
1725                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1726                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1727                 }
1728
1729                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1730                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1731                 } else {
1732                         $useIndex = '';
1733                 }
1734                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1735                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1736                 } else {
1737                         $ignoreIndex = '';
1738                 }
1739
1740                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1741         }
1742
1743         /**
1744          * Returns an optional GROUP BY with an optional HAVING
1745          *
1746          * @param array $options Associative array of options
1747          * @return string
1748          * @see Database::select()
1749          * @since 1.21
1750          */
1751         protected function makeGroupByWithHaving( $options ) {
1752                 $sql = '';
1753                 if ( isset( $options['GROUP BY'] ) ) {
1754                         $gb = is_array( $options['GROUP BY'] )
1755                                 ? implode( ',', $options['GROUP BY'] )
1756                                 : $options['GROUP BY'];
1757                         $sql .= ' GROUP BY ' . $gb;
1758                 }
1759                 if ( isset( $options['HAVING'] ) ) {
1760                         $having = is_array( $options['HAVING'] )
1761                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1762                                 : $options['HAVING'];
1763                         $sql .= ' HAVING ' . $having;
1764                 }
1765
1766                 return $sql;
1767         }
1768
1769         /**
1770          * Returns an optional ORDER BY
1771          *
1772          * @param array $options Associative array of options
1773          * @return string
1774          * @see Database::select()
1775          * @since 1.21
1776          */
1777         protected function makeOrderBy( $options ) {
1778                 if ( isset( $options['ORDER BY'] ) ) {
1779                         $ob = is_array( $options['ORDER BY'] )
1780                                 ? implode( ',', $options['ORDER BY'] )
1781                                 : $options['ORDER BY'];
1782
1783                         return ' ORDER BY ' . $ob;
1784                 }
1785
1786                 return '';
1787         }
1788
1789         public function select(
1790                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1791         ) {
1792                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1793
1794                 return $this->query( $sql, $fname );
1795         }
1796
1797         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1798                 $options = [], $join_conds = []
1799         ) {
1800                 if ( is_array( $vars ) ) {
1801                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1802                 } else {
1803                         $fields = $vars;
1804                 }
1805
1806                 $options = (array)$options;
1807                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1808                         ? $options['USE INDEX']
1809                         : [];
1810                 $ignoreIndexes = (
1811                         isset( $options['IGNORE INDEX'] ) &&
1812                         is_array( $options['IGNORE INDEX'] )
1813                 )
1814                         ? $options['IGNORE INDEX']
1815                         : [];
1816
1817                 if (
1818                         $this->selectOptionsIncludeLocking( $options ) &&
1819                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1820                 ) {
1821                         // Some DB types (e.g. postgres) disallow FOR UPDATE with aggregate
1822                         // functions. Discourage use of such queries to encourage compatibility.
1823                         call_user_func(
1824                                 $this->deprecationLogger,
1825                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)"
1826                         );
1827                 }
1828
1829                 if ( is_array( $table ) ) {
1830                         $from = ' FROM ' .
1831                                 $this->tableNamesWithIndexClauseOrJOIN(
1832                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1833                 } elseif ( $table != '' ) {
1834                         $from = ' FROM ' .
1835                                 $this->tableNamesWithIndexClauseOrJOIN(
1836                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1837                 } else {
1838                         $from = '';
1839                 }
1840
1841                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1842                         $this->makeSelectOptions( $options );
1843
1844                 if ( is_array( $conds ) ) {
1845                         $conds = $this->makeList( $conds, self::LIST_AND );
1846                 }
1847
1848                 if ( $conds === null || $conds === false ) {
1849                         $this->queryLogger->warning(
1850                                 __METHOD__
1851                                 . ' called from '
1852                                 . $fname
1853                                 . ' with incorrect parameters: $conds must be a string or an array'
1854                         );
1855                         $conds = '';
1856                 }
1857
1858                 if ( $conds === '' || $conds === '*' ) {
1859                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1860                 } elseif ( is_string( $conds ) ) {
1861                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1862                                 "WHERE $conds $preLimitTail";
1863                 } else {
1864                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1865                 }
1866
1867                 if ( isset( $options['LIMIT'] ) ) {
1868                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1869                                 $options['OFFSET'] ?? false );
1870                 }
1871                 $sql = "$sql $postLimitTail";
1872
1873                 if ( isset( $options['EXPLAIN'] ) ) {
1874                         $sql = 'EXPLAIN ' . $sql;
1875                 }
1876
1877                 return $sql;
1878         }
1879
1880         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1881                 $options = [], $join_conds = []
1882         ) {
1883                 $options = (array)$options;
1884                 $options['LIMIT'] = 1;
1885
1886                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1887                 if ( $res === false ) {
1888                         throw new DBUnexpectedError( $this, "Got false from select()" );
1889                 }
1890
1891                 if ( !$this->numRows( $res ) ) {
1892                         return false;
1893                 }
1894
1895                 return $this->fetchObject( $res );
1896         }
1897
1898         public function estimateRowCount(
1899                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1900         ) {
1901                 $conds = $this->normalizeConditions( $conds, $fname );
1902                 $column = $this->extractSingleFieldFromList( $var );
1903                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1904                         $conds[] = "$column IS NOT NULL";
1905                 }
1906
1907                 $res = $this->select(
1908                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1909                 );
1910                 $row = $res ? $this->fetchRow( $res ) : [];
1911
1912                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1913         }
1914
1915         public function selectRowCount(
1916                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1917         ) {
1918                 $conds = $this->normalizeConditions( $conds, $fname );
1919                 $column = $this->extractSingleFieldFromList( $var );
1920                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1921                         $conds[] = "$column IS NOT NULL";
1922                 }
1923
1924                 $res = $this->select(
1925                         [
1926                                 'tmp_count' => $this->buildSelectSubquery(
1927                                         $tables,
1928                                         '1',
1929                                         $conds,
1930                                         $fname,
1931                                         $options,
1932                                         $join_conds
1933                                 )
1934                         ],
1935                         [ 'rowcount' => 'COUNT(*)' ],
1936                         [],
1937                         $fname
1938                 );
1939                 $row = $res ? $this->fetchRow( $res ) : [];
1940
1941                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1942         }
1943
1944         /**
1945          * @param string|array $options
1946          * @return bool
1947          */
1948         private function selectOptionsIncludeLocking( $options ) {
1949                 $options = (array)$options;
1950                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1951                         if ( in_array( $lock, $options, true ) ) {
1952                                 return true;
1953                         }
1954                 }
1955
1956                 return false;
1957         }
1958
1959         /**
1960          * @param array|string $fields
1961          * @param array|string $options
1962          * @return bool
1963          */
1964         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1965                 foreach ( (array)$options as $key => $value ) {
1966                         if ( is_string( $key ) ) {
1967                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1968                                         return true;
1969                                 }
1970                         } elseif ( is_string( $value ) ) {
1971                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1972                                         return true;
1973                                 }
1974                         }
1975                 }
1976
1977                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1978                 foreach ( (array)$fields as $field ) {
1979                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1980                                 return true;
1981                         }
1982                 }
1983
1984                 return false;
1985         }
1986
1987         /**
1988          * @param array|string $conds
1989          * @param string $fname
1990          * @return array
1991          */
1992         final protected function normalizeConditions( $conds, $fname ) {
1993                 if ( $conds === null || $conds === false ) {
1994                         $this->queryLogger->warning(
1995                                 __METHOD__
1996                                 . ' called from '
1997                                 . $fname
1998                                 . ' with incorrect parameters: $conds must be a string or an array'
1999                         );
2000                         $conds = '';
2001                 }
2002
2003                 if ( !is_array( $conds ) ) {
2004                         $conds = ( $conds === '' ) ? [] : [ $conds ];
2005                 }
2006
2007                 return $conds;
2008         }
2009
2010         /**
2011          * @param array|string $var Field parameter in the style of select()
2012          * @return string|null Column name or null; ignores aliases
2013          * @throws DBUnexpectedError Errors out if multiple columns are given
2014          */
2015         final protected function extractSingleFieldFromList( $var ) {
2016                 if ( is_array( $var ) ) {
2017                         if ( !$var ) {
2018                                 $column = null;
2019                         } elseif ( count( $var ) == 1 ) {
2020                                 $column = $var[0] ?? reset( $var );
2021                         } else {
2022                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns' );
2023                         }
2024                 } else {
2025                         $column = $var;
2026                 }
2027
2028                 return $column;
2029         }
2030
2031         public function lockForUpdate(
2032                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
2033         ) {
2034                 if ( !$this->trxLevel() && !$this->getFlag( self::DBO_TRX ) ) {
2035                         throw new DBUnexpectedError(
2036                                 $this,
2037                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
2038                         );
2039                 }
2040
2041                 $options = (array)$options;
2042                 $options[] = 'FOR UPDATE';
2043
2044                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
2045         }
2046
2047         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2048                 $info = $this->fieldInfo( $table, $field );
2049
2050                 return (bool)$info;
2051         }
2052
2053         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2054                 if ( !$this->tableExists( $table ) ) {
2055                         return null;
2056                 }
2057
2058                 $info = $this->indexInfo( $table, $index, $fname );
2059                 if ( is_null( $info ) ) {
2060                         return null;
2061                 } else {
2062                         return $info !== false;
2063                 }
2064         }
2065
2066         abstract public function tableExists( $table, $fname = __METHOD__ );
2067
2068         public function indexUnique( $table, $index ) {
2069                 $indexInfo = $this->indexInfo( $table, $index );
2070
2071                 if ( !$indexInfo ) {
2072                         return null;
2073                 }
2074
2075                 return !$indexInfo[0]->Non_unique;
2076         }
2077
2078         /**
2079          * Helper for Database::insert().
2080          *
2081          * @param array $options
2082          * @return string
2083          */
2084         protected function makeInsertOptions( $options ) {
2085                 return implode( ' ', $options );
2086         }
2087
2088         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2089                 # No rows to insert, easy just return now
2090                 if ( !count( $a ) ) {
2091                         return true;
2092                 }
2093
2094                 $table = $this->tableName( $table );
2095
2096                 if ( !is_array( $options ) ) {
2097                         $options = [ $options ];
2098                 }
2099
2100                 $options = $this->makeInsertOptions( $options );
2101
2102                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2103                         $multi = true;
2104                         $keys = array_keys( $a[0] );
2105                 } else {
2106                         $multi = false;
2107                         $keys = array_keys( $a );
2108                 }
2109
2110                 $sql = 'INSERT ' . $options .
2111                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2112
2113                 if ( $multi ) {
2114                         $first = true;
2115                         foreach ( $a as $row ) {
2116                                 if ( $first ) {
2117                                         $first = false;
2118                                 } else {
2119                                         $sql .= ',';
2120                                 }
2121                                 $sql .= '(' . $this->makeList( $row ) . ')';
2122                         }
2123                 } else {
2124                         $sql .= '(' . $this->makeList( $a ) . ')';
2125                 }
2126
2127                 $this->query( $sql, $fname );
2128
2129                 return true;
2130         }
2131
2132         /**
2133          * Make UPDATE options array for Database::makeUpdateOptions
2134          *
2135          * @param array $options
2136          * @return array
2137          */
2138         protected function makeUpdateOptionsArray( $options ) {
2139                 if ( !is_array( $options ) ) {
2140                         $options = [ $options ];
2141                 }
2142
2143                 $opts = [];
2144
2145                 if ( in_array( 'IGNORE', $options ) ) {
2146                         $opts[] = 'IGNORE';
2147                 }
2148
2149                 return $opts;
2150         }
2151
2152         /**
2153          * Make UPDATE options for the Database::update function
2154          *
2155          * @param array $options The options passed to Database::update
2156          * @return string
2157          */
2158         protected function makeUpdateOptions( $options ) {
2159                 $opts = $this->makeUpdateOptionsArray( $options );
2160
2161                 return implode( ' ', $opts );
2162         }
2163
2164         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2165                 $table = $this->tableName( $table );
2166                 $opts = $this->makeUpdateOptions( $options );
2167                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2168
2169                 if ( $conds !== [] && $conds !== '*' ) {
2170                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2171                 }
2172
2173                 $this->query( $sql, $fname );
2174
2175                 return true;
2176         }
2177
2178         public function makeList( $a, $mode = self::LIST_COMMA ) {
2179                 if ( !is_array( $a ) ) {
2180                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2181                 }
2182
2183                 $first = true;
2184                 $list = '';
2185
2186                 foreach ( $a as $field => $value ) {
2187                         if ( !$first ) {
2188                                 if ( $mode == self::LIST_AND ) {
2189                                         $list .= ' AND ';
2190                                 } elseif ( $mode == self::LIST_OR ) {
2191                                         $list .= ' OR ';
2192                                 } else {
2193                                         $list .= ',';
2194                                 }
2195                         } else {
2196                                 $first = false;
2197                         }
2198
2199                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2200                                 $list .= "($value)";
2201                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2202                                 $list .= "$value";
2203                         } elseif (
2204                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2205                         ) {
2206                                 // Remove null from array to be handled separately if found
2207                                 $includeNull = false;
2208                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2209                                         $includeNull = true;
2210                                         unset( $value[$nullKey] );
2211                                 }
2212                                 if ( count( $value ) == 0 && !$includeNull ) {
2213                                         throw new InvalidArgumentException(
2214                                                 __METHOD__ . ": empty input for field $field" );
2215                                 } elseif ( count( $value ) == 0 ) {
2216                                         // only check if $field is null
2217                                         $list .= "$field IS NULL";
2218                                 } else {
2219                                         // IN clause contains at least one valid element
2220                                         if ( $includeNull ) {
2221                                                 // Group subconditions to ensure correct precedence
2222                                                 $list .= '(';
2223                                         }
2224                                         if ( count( $value ) == 1 ) {
2225                                                 // Special-case single values, as IN isn't terribly efficient
2226                                                 // Don't necessarily assume the single key is 0; we don't
2227                                                 // enforce linear numeric ordering on other arrays here.
2228                                                 $value = array_values( $value )[0];
2229                                                 $list .= $field . " = " . $this->addQuotes( $value );
2230                                         } else {
2231                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2232                                         }
2233                                         // if null present in array, append IS NULL
2234                                         if ( $includeNull ) {
2235                                                 $list .= " OR $field IS NULL)";
2236                                         }
2237                                 }
2238                         } elseif ( $value === null ) {
2239                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2240                                         $list .= "$field IS ";
2241                                 } elseif ( $mode == self::LIST_SET ) {
2242                                         $list .= "$field = ";
2243                                 }
2244                                 $list .= 'NULL';
2245                         } else {
2246                                 if (
2247                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2248                                 ) {
2249                                         $list .= "$field = ";
2250                                 }
2251                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2252                         }
2253                 }
2254
2255                 return $list;
2256         }
2257
2258         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2259                 $conds = [];
2260
2261                 foreach ( $data as $base => $sub ) {
2262                         if ( count( $sub ) ) {
2263                                 $conds[] = $this->makeList(
2264                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2265                                         self::LIST_AND );
2266                         }
2267                 }
2268
2269                 if ( $conds ) {
2270                         return $this->makeList( $conds, self::LIST_OR );
2271                 } else {
2272                         // Nothing to search for...
2273                         return false;
2274                 }
2275         }
2276
2277         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2278                 return $valuename;
2279         }
2280
2281         public function bitNot( $field ) {
2282                 return "(~$field)";
2283         }
2284
2285         public function bitAnd( $fieldLeft, $fieldRight ) {
2286                 return "($fieldLeft & $fieldRight)";
2287         }
2288
2289         public function bitOr( $fieldLeft, $fieldRight ) {
2290                 return "($fieldLeft | $fieldRight)";
2291         }
2292
2293         public function buildConcat( $stringList ) {
2294                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2295         }
2296
2297         public function buildGroupConcatField(
2298                 $delim, $table, $field, $conds = '', $join_conds = []
2299         ) {
2300                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2301
2302                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2303         }
2304
2305         public function buildSubstring( $input, $startPosition, $length = null ) {
2306                 $this->assertBuildSubstringParams( $startPosition, $length );
2307                 $functionBody = "$input FROM $startPosition";
2308                 if ( $length !== null ) {
2309                         $functionBody .= " FOR $length";
2310                 }
2311                 return 'SUBSTRING(' . $functionBody . ')';
2312         }
2313
2314         /**
2315          * Check type and bounds for parameters to self::buildSubstring()
2316          *
2317          * All supported databases have substring functions that behave the same for
2318          * positive $startPosition and non-negative $length, but behaviors differ when
2319          * given 0 or negative $startPosition or negative $length. The simplest
2320          * solution to that is to just forbid those values.
2321          *
2322          * @param int $startPosition
2323          * @param int|null $length
2324          * @since 1.31
2325          */
2326         protected function assertBuildSubstringParams( $startPosition, $length ) {
2327                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2328                         throw new InvalidArgumentException(
2329                                 '$startPosition must be a positive integer'
2330                         );
2331                 }
2332                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2333                         throw new InvalidArgumentException(
2334                                 '$length must be null or an integer greater than or equal to 0'
2335                         );
2336                 }
2337         }
2338
2339         public function buildStringCast( $field ) {
2340                 // In theory this should work for any standards-compliant
2341                 // SQL implementation, although it may not be the best way to do it.
2342                 return "CAST( $field AS CHARACTER )";
2343         }
2344
2345         public function buildIntegerCast( $field ) {
2346                 return 'CAST( ' . $field . ' AS INTEGER )';
2347         }
2348
2349         public function buildSelectSubquery(
2350                 $table, $vars, $conds = '', $fname = __METHOD__,
2351                 $options = [], $join_conds = []
2352         ) {
2353                 return new Subquery(
2354                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2355                 );
2356         }
2357
2358         public function databasesAreIndependent() {
2359                 return false;
2360         }
2361
2362         final public function selectDB( $db ) {
2363                 $this->selectDomain( new DatabaseDomain(
2364                         $db,
2365                         $this->currentDomain->getSchema(),
2366                         $this->currentDomain->getTablePrefix()
2367                 ) );
2368
2369                 return true;
2370         }
2371
2372         final public function selectDomain( $domain ) {
2373                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2374         }
2375
2376         /**
2377          * @param DatabaseDomain $domain
2378          * @throws DBConnectionError
2379          * @throws DBError
2380          * @since 1.32
2381          */
2382         protected function doSelectDomain( DatabaseDomain $domain ) {
2383                 $this->currentDomain = $domain;
2384         }
2385
2386         public function getDBname() {
2387                 return $this->currentDomain->getDatabase();
2388         }
2389
2390         public function getServer() {
2391                 return $this->server;
2392         }
2393
2394         public function tableName( $name, $format = 'quoted' ) {
2395                 if ( $name instanceof Subquery ) {
2396                         throw new DBUnexpectedError(
2397                                 $this,
2398                                 __METHOD__ . ': got Subquery instance when expecting a string'
2399                         );
2400                 }
2401
2402                 # Skip the entire process when we have a string quoted on both ends.
2403                 # Note that we check the end so that we will still quote any use of
2404                 # use of `database`.table. But won't break things if someone wants
2405                 # to query a database table with a dot in the name.
2406                 if ( $this->isQuotedIdentifier( $name ) ) {
2407                         return $name;
2408                 }
2409
2410                 # Lets test for any bits of text that should never show up in a table
2411                 # name. Basically anything like JOIN or ON which are actually part of
2412                 # SQL queries, but may end up inside of the table value to combine
2413                 # sql. Such as how the API is doing.
2414                 # Note that we use a whitespace test rather than a \b test to avoid
2415                 # any remote case where a word like on may be inside of a table name
2416                 # surrounded by symbols which may be considered word breaks.
2417                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2418                         $this->queryLogger->warning(
2419                                 __METHOD__ . ": use of subqueries is not supported this way",
2420                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2421                         );
2422
2423                         return $name;
2424                 }
2425
2426                 # Split database and table into proper variables.
2427                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2428
2429                 # Quote $table and apply the prefix if not quoted.
2430                 # $tableName might be empty if this is called from Database::replaceVars()
2431                 $tableName = "{$prefix}{$table}";
2432                 if ( $format === 'quoted'
2433                         && !$this->isQuotedIdentifier( $tableName )
2434                         && $tableName !== ''
2435                 ) {
2436                         $tableName = $this->addIdentifierQuotes( $tableName );
2437                 }
2438
2439                 # Quote $schema and $database and merge them with the table name if needed
2440                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2441                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2442
2443                 return $tableName;
2444         }
2445
2446         /**
2447          * Get the table components needed for a query given the currently selected database
2448          *
2449          * @param string $name Table name in the form of db.schema.table, db.table, or table
2450          * @return array (DB name or "" for default, schema name, table prefix, table name)
2451          */
2452         protected function qualifiedTableComponents( $name ) {
2453                 # We reverse the explode so that database.table and table both output the correct table.
2454                 $dbDetails = explode( '.', $name, 3 );
2455                 if ( count( $dbDetails ) == 3 ) {
2456                         list( $database, $schema, $table ) = $dbDetails;
2457                         # We don't want any prefix added in this case
2458                         $prefix = '';
2459                 } elseif ( count( $dbDetails ) == 2 ) {
2460                         list( $database, $table ) = $dbDetails;
2461                         # We don't want any prefix added in this case
2462                         $prefix = '';
2463                         # In dbs that support it, $database may actually be the schema
2464                         # but that doesn't affect any of the functionality here
2465                         $schema = '';
2466                 } else {
2467                         list( $table ) = $dbDetails;
2468                         if ( isset( $this->tableAliases[$table] ) ) {
2469                                 $database = $this->tableAliases[$table]['dbname'];
2470                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2471                                         ? $this->tableAliases[$table]['schema']
2472                                         : $this->relationSchemaQualifier();
2473                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2474                                         ? $this->tableAliases[$table]['prefix']
2475                                         : $this->tablePrefix();
2476                         } else {
2477                                 $database = '';
2478                                 $schema = $this->relationSchemaQualifier(); # Default schema
2479                                 $prefix = $this->tablePrefix(); # Default prefix
2480                         }
2481                 }
2482
2483                 return [ $database, $schema, $prefix, $table ];
2484         }
2485
2486         /**
2487          * @param string|null $namespace Database or schema
2488          * @param string $relation Name of table, view, sequence, etc...
2489          * @param string $format One of (raw, quoted)
2490          * @return string Relation name with quoted and merged $namespace as needed
2491          */
2492         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2493                 if ( strlen( $namespace ) ) {
2494                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2495                                 $namespace = $this->addIdentifierQuotes( $namespace );
2496                         }
2497                         $relation = $namespace . '.' . $relation;
2498                 }
2499
2500                 return $relation;
2501         }
2502
2503         public function tableNames() {
2504                 $inArray = func_get_args();
2505                 $retVal = [];
2506
2507                 foreach ( $inArray as $name ) {
2508                         $retVal[$name] = $this->tableName( $name );
2509                 }
2510
2511                 return $retVal;
2512         }
2513
2514         public function tableNamesN() {
2515                 $inArray = func_get_args();
2516                 $retVal = [];
2517
2518                 foreach ( $inArray as $name ) {
2519                         $retVal[] = $this->tableName( $name );
2520                 }
2521
2522                 return $retVal;
2523         }
2524
2525         /**
2526          * Get an aliased table name
2527          *
2528          * This returns strings like "tableName AS newTableName" for aliased tables
2529          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2530          *
2531          * @see Database::tableName()
2532          * @param string|Subquery $table Table name or object with a 'sql' field
2533          * @param string|bool $alias Table alias (optional)
2534          * @return string SQL name for aliased table. Will not alias a table to its own name
2535          */
2536         protected function tableNameWithAlias( $table, $alias = false ) {
2537                 if ( is_string( $table ) ) {
2538                         $quotedTable = $this->tableName( $table );
2539                 } elseif ( $table instanceof Subquery ) {
2540                         $quotedTable = (string)$table;
2541                 } else {
2542                         throw new InvalidArgumentException( "Table must be a string or Subquery" );
2543                 }
2544
2545                 if ( $alias === false || $alias === $table ) {
2546                         if ( $table instanceof Subquery ) {
2547                                 throw new InvalidArgumentException( "Subquery table missing alias" );
2548                         }
2549
2550                         return $quotedTable;
2551                 } else {
2552                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2553                 }
2554         }
2555
2556         /**
2557          * Gets an array of aliased table names
2558          *
2559          * @param array $tables [ [alias] => table ]
2560          * @return string[] See tableNameWithAlias()
2561          */
2562         protected function tableNamesWithAlias( $tables ) {
2563                 $retval = [];
2564                 foreach ( $tables as $alias => $table ) {
2565                         if ( is_numeric( $alias ) ) {
2566                                 $alias = $table;
2567                         }
2568                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2569                 }
2570
2571                 return $retval;
2572         }
2573
2574         /**
2575          * Get an aliased field name
2576          * e.g. fieldName AS newFieldName
2577          *
2578          * @param string $name Field name
2579          * @param string|bool $alias Alias (optional)
2580          * @return string SQL name for aliased field. Will not alias a field to its own name
2581          */
2582         protected function fieldNameWithAlias( $name, $alias = false ) {
2583                 if ( !$alias || (string)$alias === (string)$name ) {
2584                         return $name;
2585                 } else {
2586                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2587                 }
2588         }
2589
2590         /**
2591          * Gets an array of aliased field names
2592          *
2593          * @param array $fields [ [alias] => field ]
2594          * @return string[] See fieldNameWithAlias()
2595          */
2596         protected function fieldNamesWithAlias( $fields ) {
2597                 $retval = [];
2598                 foreach ( $fields as $alias => $field ) {
2599                         if ( is_numeric( $alias ) ) {
2600                                 $alias = $field;
2601                         }
2602                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2603                 }
2604
2605                 return $retval;
2606         }
2607
2608         /**
2609          * Get the aliased table name clause for a FROM clause
2610          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2611          *
2612          * @param array $tables ( [alias] => table )
2613          * @param array $use_index Same as for select()
2614          * @param array $ignore_index Same as for select()
2615          * @param array $join_conds Same as for select()
2616          * @return string
2617          */
2618         protected function tableNamesWithIndexClauseOrJOIN(
2619                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2620         ) {
2621                 $ret = [];
2622                 $retJOIN = [];
2623                 $use_index = (array)$use_index;
2624                 $ignore_index = (array)$ignore_index;
2625                 $join_conds = (array)$join_conds;
2626
2627                 foreach ( $tables as $alias => $table ) {
2628                         if ( !is_string( $alias ) ) {
2629                                 // No alias? Set it equal to the table name
2630                                 $alias = $table;
2631                         }
2632
2633                         if ( is_array( $table ) ) {
2634                                 // A parenthesized group
2635                                 if ( count( $table ) > 1 ) {
2636                                         $joinedTable = '(' .
2637                                                 $this->tableNamesWithIndexClauseOrJOIN(
2638                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2639                                 } else {
2640                                         // Degenerate case
2641                                         $innerTable = reset( $table );
2642                                         $innerAlias = key( $table );
2643                                         $joinedTable = $this->tableNameWithAlias(
2644                                                 $innerTable,
2645                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2646                                         );
2647                                 }
2648                         } else {
2649                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2650                         }
2651
2652                         // Is there a JOIN clause for this table?
2653                         if ( isset( $join_conds[$alias] ) ) {
2654                                 list( $joinType, $conds ) = $join_conds[$alias];
2655                                 $tableClause = $joinType;
2656                                 $tableClause .= ' ' . $joinedTable;
2657                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2658                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2659                                         if ( $use != '' ) {
2660                                                 $tableClause .= ' ' . $use;
2661                                         }
2662                                 }
2663                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2664                                         $ignore = $this->ignoreIndexClause(
2665                                                 implode( ',', (array)$ignore_index[$alias] ) );
2666                                         if ( $ignore != '' ) {
2667                                                 $tableClause .= ' ' . $ignore;
2668                                         }
2669                                 }
2670                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2671                                 if ( $on != '' ) {
2672                                         $tableClause .= ' ON (' . $on . ')';
2673                                 }
2674
2675                                 $retJOIN[] = $tableClause;
2676                         } elseif ( isset( $use_index[$alias] ) ) {
2677                                 // Is there an INDEX clause for this table?
2678                                 $tableClause = $joinedTable;
2679                                 $tableClause .= ' ' . $this->useIndexClause(
2680                                                 implode( ',', (array)$use_index[$alias] )
2681                                         );
2682
2683                                 $ret[] = $tableClause;
2684                         } elseif ( isset( $ignore_index[$alias] ) ) {
2685                                 // Is there an INDEX clause for this table?
2686                                 $tableClause = $joinedTable;
2687                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2688                                                 implode( ',', (array)$ignore_index[$alias] )
2689                                         );
2690
2691                                 $ret[] = $tableClause;
2692                         } else {
2693                                 $tableClause = $joinedTable;
2694
2695                                 $ret[] = $tableClause;
2696                         }
2697                 }
2698
2699                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2700                 $implicitJoins = implode( ',', $ret );
2701                 $explicitJoins = implode( ' ', $retJOIN );
2702
2703                 // Compile our final table clause
2704                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2705         }
2706
2707         /**
2708          * Allows for index remapping in queries where this is not consistent across DBMS
2709          *
2710          * @param string $index
2711          * @return string
2712          */
2713         protected function indexName( $index ) {
2714                 return $this->indexAliases[$index] ?? $index;
2715         }
2716
2717         public function addQuotes( $s ) {
2718                 if ( $s instanceof Blob ) {
2719                         $s = $s->fetch();
2720                 }
2721                 if ( $s === null ) {
2722                         return 'NULL';
2723                 } elseif ( is_bool( $s ) ) {
2724                         return (int)$s;
2725                 } else {
2726                         # This will also quote numeric values. This should be harmless,
2727                         # and protects against weird problems that occur when they really
2728                         # _are_ strings such as article titles and string->number->string
2729                         # conversion is not 1:1.
2730                         return "'" . $this->strencode( $s ) . "'";
2731                 }
2732         }
2733
2734         public function addIdentifierQuotes( $s ) {
2735                 return '"' . str_replace( '"', '""', $s ) . '"';
2736         }
2737
2738         /**
2739          * Returns if the given identifier looks quoted or not according to
2740          * the database convention for quoting identifiers .
2741          *
2742          * @note Do not use this to determine if untrusted input is safe.
2743          *   A malicious user can trick this function.
2744          * @param string $name
2745          * @return bool
2746          */
2747         public function isQuotedIdentifier( $name ) {
2748                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2749         }
2750
2751         /**
2752          * @param string $s
2753          * @param string $escapeChar
2754          * @return string
2755          */
2756         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2757                 return str_replace( [ $escapeChar, '%', '_' ],
2758                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2759                         $s );
2760         }
2761
2762         public function buildLike( $param, ...$params ) {
2763                 if ( is_array( $param ) ) {
2764                         $params = $param;
2765                 } else {
2766                         $params = func_get_args();
2767                 }
2768
2769                 $s = '';
2770
2771                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2772                 // may escape backslashes, creating problems of double escaping. The `
2773                 // character has good cross-DBMS compatibility, avoiding special operators
2774                 // in MS SQL like ^ and %
2775                 $escapeChar = '`';
2776
2777                 foreach ( $params as $value ) {
2778                         if ( $value instanceof LikeMatch ) {
2779                                 $s .= $value->toString();
2780                         } else {
2781                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2782                         }
2783                 }
2784
2785                 return ' LIKE ' .
2786                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2787         }
2788
2789         public function anyChar() {
2790                 return new LikeMatch( '_' );
2791         }
2792
2793         public function anyString() {
2794                 return new LikeMatch( '%' );
2795         }
2796
2797         public function nextSequenceValue( $seqName ) {
2798                 return null;
2799         }
2800
2801         /**
2802          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2803          * is only needed because a) MySQL must be as efficient as possible due to
2804          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2805          * which index to pick. Anyway, other databases might have different
2806          * indexes on a given table. So don't bother overriding this unless you're
2807          * MySQL.
2808          * @param string $index
2809          * @return string
2810          */
2811         public function useIndexClause( $index ) {
2812                 return '';
2813         }
2814
2815         /**
2816          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2817          * is only needed because a) MySQL must be as efficient as possible due to
2818          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2819          * which index to pick. Anyway, other databases might have different
2820          * indexes on a given table. So don't bother overriding this unless you're
2821          * MySQL.
2822          * @param string $index
2823          * @return string
2824          */
2825         public function ignoreIndexClause( $index ) {
2826                 return '';
2827         }
2828
2829         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2830                 if ( count( $rows ) == 0 ) {
2831                         return;
2832                 }
2833
2834                 $uniqueIndexes = (array)$uniqueIndexes;
2835                 // Single row case
2836                 if ( !is_array( reset( $rows ) ) ) {
2837                         $rows = [ $rows ];
2838                 }
2839
2840                 try {
2841                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2842                         $affectedRowCount = 0;
2843                         foreach ( $rows as $row ) {
2844                                 // Delete rows which collide with this one
2845                                 $indexWhereClauses = [];
2846                                 foreach ( $uniqueIndexes as $index ) {
2847                                         $indexColumns = (array)$index;
2848                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2849                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2850                                                 throw new DBUnexpectedError(
2851                                                         $this,
2852                                                         'New record does not provide all values for unique key (' .
2853                                                         implode( ', ', $indexColumns ) . ')'
2854                                                 );
2855                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2856                                                 throw new DBUnexpectedError(
2857                                                         $this,
2858                                                         'New record has a null value for unique key (' .
2859                                                         implode( ', ', $indexColumns ) . ')'
2860                                                 );
2861                                         }
2862                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2863                                 }
2864
2865                                 if ( $indexWhereClauses ) {
2866                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2867                                         $affectedRowCount += $this->affectedRows();
2868                                 }
2869
2870                                 // Now insert the row
2871                                 $this->insert( $table, $row, $fname );
2872                                 $affectedRowCount += $this->affectedRows();
2873                         }
2874                         $this->endAtomic( $fname );
2875                         $this->affectedRowCount = $affectedRowCount;
2876                 } catch ( Exception $e ) {
2877                         $this->cancelAtomic( $fname );
2878                         throw $e;
2879                 }
2880         }
2881
2882         /**
2883          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2884          * statement.
2885          *
2886          * @param string $table Table name
2887          * @param array|string $rows Row(s) to insert
2888          * @param string $fname Caller function name
2889          */
2890         protected function nativeReplace( $table, $rows, $fname ) {
2891                 $table = $this->tableName( $table );
2892
2893                 # Single row case
2894                 if ( !is_array( reset( $rows ) ) ) {
2895                         $rows = [ $rows ];
2896                 }
2897
2898                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2899                 $first = true;
2900
2901                 foreach ( $rows as $row ) {
2902                         if ( $first ) {
2903                                 $first = false;
2904                         } else {
2905                                 $sql .= ',';
2906                         }
2907
2908                         $sql .= '(' . $this->makeList( $row ) . ')';
2909                 }
2910
2911                 $this->query( $sql, $fname );
2912         }
2913
2914         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2915                 $fname = __METHOD__
2916         ) {
2917                 if ( $rows === [] ) {
2918                         return true; // nothing to do
2919                 }
2920
2921                 $uniqueIndexes = (array)$uniqueIndexes;
2922                 if ( !is_array( reset( $rows ) ) ) {
2923                         $rows = [ $rows ];
2924                 }
2925
2926                 if ( count( $uniqueIndexes ) ) {
2927                         $clauses = []; // list WHERE clauses that each identify a single row
2928                         foreach ( $rows as $row ) {
2929                                 foreach ( $uniqueIndexes as $index ) {
2930                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2931                                         $rowKey = []; // unique key to this row
2932                                         foreach ( $index as $column ) {
2933                                                 $rowKey[$column] = $row[$column];
2934                                         }
2935                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2936                                 }
2937                         }
2938                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2939                 } else {
2940                         $where = false;
2941                 }
2942
2943                 $affectedRowCount = 0;
2944                 try {
2945                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2946                         # Update any existing conflicting row(s)
2947                         if ( $where !== false ) {
2948                                 $this->update( $table, $set, $where, $fname );
2949                                 $affectedRowCount += $this->affectedRows();
2950                         }
2951                         # Now insert any non-conflicting row(s)
2952                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2953                         $affectedRowCount += $this->affectedRows();
2954                         $this->endAtomic( $fname );
2955                         $this->affectedRowCount = $affectedRowCount;
2956                 } catch ( Exception $e ) {
2957                         $this->cancelAtomic( $fname );
2958                         throw $e;
2959                 }
2960
2961                 return true;
2962         }
2963
2964         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2965                 $fname = __METHOD__
2966         ) {
2967                 if ( !$conds ) {
2968                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2969                 }
2970
2971                 $delTable = $this->tableName( $delTable );
2972                 $joinTable = $this->tableName( $joinTable );
2973                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2974                 if ( $conds != '*' ) {
2975                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2976                 }
2977                 $sql .= ')';
2978
2979                 $this->query( $sql, $fname );
2980         }
2981
2982         public function textFieldSize( $table, $field ) {
2983                 $table = $this->tableName( $table );
2984                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\"";
2985                 $res = $this->query( $sql, __METHOD__ );
2986                 $row = $this->fetchObject( $res );
2987
2988                 $m = [];
2989
2990                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2991                         $size = $m[1];
2992                 } else {
2993                         $size = -1;
2994                 }
2995
2996                 return $size;
2997         }
2998
2999         public function delete( $table, $conds, $fname = __METHOD__ ) {
3000                 if ( !$conds ) {
3001                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
3002                 }
3003
3004                 $table = $this->tableName( $table );
3005                 $sql = "DELETE FROM $table";
3006
3007                 if ( $conds != '*' ) {
3008                         if ( is_array( $conds ) ) {
3009                                 $conds = $this->makeList( $conds, self::LIST_AND );
3010                         }
3011                         $sql .= ' WHERE ' . $conds;
3012                 }
3013
3014                 $this->query( $sql, $fname );
3015
3016                 return true;
3017         }
3018
3019         final public function insertSelect(
3020                 $destTable, $srcTable, $varMap, $conds,
3021                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3022         ) {
3023                 static $hints = [ 'NO_AUTO_COLUMNS' ];
3024
3025                 $insertOptions = (array)$insertOptions;
3026                 $selectOptions = (array)$selectOptions;
3027
3028                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
3029                         // For massive migrations with downtime, we don't want to select everything
3030                         // into memory and OOM, so do all this native on the server side if possible.
3031                         $this->nativeInsertSelect(
3032                                 $destTable,
3033                                 $srcTable,
3034                                 $varMap,
3035                                 $conds,
3036                                 $fname,
3037                                 array_diff( $insertOptions, $hints ),
3038                                 $selectOptions,
3039                                 $selectJoinConds
3040                         );
3041                 } else {
3042                         $this->nonNativeInsertSelect(
3043                                 $destTable,
3044                                 $srcTable,
3045                                 $varMap,
3046                                 $conds,
3047                                 $fname,
3048                                 array_diff( $insertOptions, $hints ),
3049                                 $selectOptions,
3050                                 $selectJoinConds
3051                         );
3052                 }
3053
3054                 return true;
3055         }
3056
3057         /**
3058          * @param array $insertOptions INSERT options
3059          * @param array $selectOptions SELECT options
3060          * @return bool Whether an INSERT SELECT with these options will be replication safe
3061          * @since 1.31
3062          */
3063         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3064                 return true;
3065         }
3066
3067         /**
3068          * Implementation of insertSelect() based on select() and insert()
3069          *
3070          * @see IDatabase::insertSelect()
3071          * @since 1.30
3072          * @param string $destTable
3073          * @param string|array $srcTable
3074          * @param array $varMap
3075          * @param array $conds
3076          * @param string $fname
3077          * @param array $insertOptions
3078          * @param array $selectOptions
3079          * @param array $selectJoinConds
3080          */
3081         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3082                 $fname = __METHOD__,
3083                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3084         ) {
3085                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3086                 // on only the master (without needing row-based-replication). It also makes it easy to
3087                 // know how big the INSERT is going to be.
3088                 $fields = [];
3089                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3090                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3091                 }
3092                 $selectOptions[] = 'FOR UPDATE';
3093                 $res = $this->select(
3094                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3095                 );
3096                 if ( !$res ) {
3097                         return;
3098                 }
3099
3100                 try {
3101                         $affectedRowCount = 0;
3102                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3103                         $rows = [];
3104                         $ok = true;
3105                         foreach ( $res as $row ) {
3106                                 $rows[] = (array)$row;
3107
3108                                 // Avoid inserts that are too huge
3109                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3110                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3111                                         if ( !$ok ) {
3112                                                 break;
3113                                         }
3114                                         $affectedRowCount += $this->affectedRows();
3115                                         $rows = [];
3116                                 }
3117                         }
3118                         if ( $rows && $ok ) {
3119                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3120                                 if ( $ok ) {
3121                                         $affectedRowCount += $this->affectedRows();
3122                                 }
3123                         }
3124                         if ( $ok ) {
3125                                 $this->endAtomic( $fname );
3126                                 $this->affectedRowCount = $affectedRowCount;
3127                         } else {
3128                                 $this->cancelAtomic( $fname );
3129                         }
3130                 } catch ( Exception $e ) {
3131                         $this->cancelAtomic( $fname );
3132                         throw $e;
3133                 }
3134         }
3135
3136         /**
3137          * Native server-side implementation of insertSelect() for situations where
3138          * we don't want to select everything into memory
3139          *
3140          * @see IDatabase::insertSelect()
3141          * @param string $destTable
3142          * @param string|array $srcTable
3143          * @param array $varMap
3144          * @param array $conds
3145          * @param string $fname
3146          * @param array $insertOptions
3147          * @param array $selectOptions
3148          * @param array $selectJoinConds
3149          */
3150         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3151                 $fname = __METHOD__,
3152                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3153         ) {
3154                 $destTable = $this->tableName( $destTable );
3155
3156                 if ( !is_array( $insertOptions ) ) {
3157                         $insertOptions = [ $insertOptions ];
3158                 }
3159
3160                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3161
3162                 $selectSql = $this->selectSQLText(
3163                         $srcTable,
3164                         array_values( $varMap ),
3165                         $conds,
3166                         $fname,
3167                         $selectOptions,
3168                         $selectJoinConds
3169                 );
3170
3171                 $sql = "INSERT $insertOptions" .
3172                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3173                         $selectSql;
3174
3175                 $this->query( $sql, $fname );
3176         }
3177
3178         public function limitResult( $sql, $limit, $offset = false ) {
3179                 if ( !is_numeric( $limit ) ) {
3180                         throw new DBUnexpectedError(
3181                                 $this,
3182                                 "Invalid non-numeric limit passed to " . __METHOD__
3183                         );
3184                 }
3185                 // This version works in MySQL and SQLite. It will very likely need to be
3186                 // overridden for most other RDBMS subclasses.
3187                 return "$sql LIMIT "
3188                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3189                         . "{$limit} ";
3190         }
3191
3192         public function unionSupportsOrderAndLimit() {
3193                 return true; // True for almost every DB supported
3194         }
3195
3196         public function unionQueries( $sqls, $all ) {
3197                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3198
3199                 return '(' . implode( $glue, $sqls ) . ')';
3200         }
3201
3202         public function unionConditionPermutations(
3203                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3204                 $options = [], $join_conds = []
3205         ) {
3206                 // First, build the Cartesian product of $permute_conds
3207                 $conds = [ [] ];
3208                 foreach ( $permute_conds as $field => $values ) {
3209                         if ( !$values ) {
3210                                 // Skip empty $values
3211                                 continue;
3212                         }
3213                         $values = array_unique( $values ); // For sanity
3214                         $newConds = [];
3215                         foreach ( $conds as $cond ) {
3216                                 foreach ( $values as $value ) {
3217                                         $cond[$field] = $value;
3218                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3219                                 }
3220                         }
3221                         $conds = $newConds;
3222                 }
3223
3224                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3225
3226                 // If there's just one condition and no subordering, hand off to
3227                 // selectSQLText directly.
3228                 if ( count( $conds ) === 1 &&
3229                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3230                 ) {
3231                         return $this->selectSQLText(
3232                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3233                         );
3234                 }
3235
3236                 // Otherwise, we need to pull out the order and limit to apply after
3237                 // the union. Then build the SQL queries for each set of conditions in
3238                 // $conds. Then union them together (using UNION ALL, because the
3239                 // product *should* already be distinct).
3240                 $orderBy = $this->makeOrderBy( $options );
3241                 $limit = $options['LIMIT'] ?? null;
3242                 $offset = $options['OFFSET'] ?? false;
3243                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3244                 if ( !$this->unionSupportsOrderAndLimit() ) {
3245                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3246                 } else {
3247                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3248                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3249                         }
3250                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3251                                 // We need to increase the limit by the offset rather than
3252                                 // using the offset directly, otherwise it'll skip incorrectly
3253                                 // in the subqueries.
3254                                 $options['LIMIT'] = $limit + $offset;
3255                                 unset( $options['OFFSET'] );
3256                         }
3257                 }
3258
3259                 $sqls = [];
3260                 foreach ( $conds as $cond ) {
3261                         $sqls[] = $this->selectSQLText(
3262                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3263                         );
3264                 }
3265                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3266                 if ( $limit !== null ) {
3267                         $sql = $this->limitResult( $sql, $limit, $offset );
3268                 }
3269
3270                 return $sql;
3271         }
3272
3273         public function conditional( $cond, $trueVal, $falseVal ) {
3274                 if ( is_array( $cond ) ) {
3275                         $cond = $this->makeList( $cond, self::LIST_AND );
3276                 }
3277
3278                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3279         }
3280
3281         public function strreplace( $orig, $old, $new ) {
3282                 return "REPLACE({$orig}, {$old}, {$new})";
3283         }
3284
3285         public function getServerUptime() {
3286                 return 0;
3287         }
3288
3289         public function wasDeadlock() {
3290                 return false;
3291         }
3292
3293         public function wasLockTimeout() {
3294                 return false;
3295         }
3296
3297         public function wasConnectionLoss() {
3298                 return $this->wasConnectionError( $this->lastErrno() );
3299         }
3300
3301         public function wasReadOnlyError() {
3302                 return false;
3303         }
3304
3305         public function wasErrorReissuable() {
3306                 return (
3307                         $this->wasDeadlock() ||
3308                         $this->wasLockTimeout() ||
3309                         $this->wasConnectionLoss()
3310                 );
3311         }
3312
3313         /**
3314          * Do not use this method outside of Database/DBError classes
3315          *
3316          * @param int|string $errno
3317          * @return bool Whether the given query error was a connection drop
3318          */
3319         public function wasConnectionError( $errno ) {
3320                 return false;
3321         }
3322
3323         /**
3324          * @return bool Whether it is known that the last query error only caused statement rollback
3325          * @note This is for backwards compatibility for callers catching DBError exceptions in
3326          *   order to ignore problems like duplicate key errors or foriegn key violations
3327          * @since 1.31
3328          */
3329         protected function wasKnownStatementRollbackError() {
3330                 return false; // don't know; it could have caused a transaction rollback
3331         }
3332
3333         public function deadlockLoop() {
3334                 $args = func_get_args();
3335                 $function = array_shift( $args );
3336                 $tries = self::$DEADLOCK_TRIES;
3337
3338                 $this->begin( __METHOD__ );
3339
3340                 $retVal = null;
3341                 /** @var Exception $e */
3342                 $e = null;
3343                 do {
3344                         try {
3345                                 $retVal = $function( ...$args );
3346                                 break;
3347                         } catch ( DBQueryError $e ) {
3348                                 if ( $this->wasDeadlock() ) {
3349                                         // Retry after a randomized delay
3350                                         usleep( mt_rand( self::$DEADLOCK_DELAY_MIN, self::$DEADLOCK_DELAY_MAX ) );
3351                                 } else {
3352                                         // Throw the error back up
3353                                         throw $e;
3354                                 }
3355                         }
3356                 } while ( --$tries > 0 );
3357
3358                 if ( $tries <= 0 ) {
3359                         // Too many deadlocks; give up
3360                         $this->rollback( __METHOD__ );
3361                         throw $e;
3362                 } else {
3363                         $this->commit( __METHOD__ );
3364
3365                         return $retVal;
3366                 }
3367         }
3368
3369         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3370                 # Real waits are implemented in the subclass.
3371                 return 0;
3372         }
3373
3374         public function getReplicaPos() {
3375                 # Stub
3376                 return false;
3377         }
3378
3379         public function getMasterPos() {
3380                 # Stub
3381                 return false;
3382         }
3383
3384         public function serverIsReadOnly() {
3385                 return false;
3386         }
3387
3388         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3389                 if ( !$this->trxLevel() ) {
3390                         throw new DBUnexpectedError( $this, "No transaction is active" );
3391                 }
3392                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3393         }
3394
3395         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3396                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3397                         // Start an implicit transaction similar to how query() does
3398                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3399                         $this->trxAutomatic = true;
3400                 }
3401
3402                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3403                 if ( !$this->trxLevel() ) {
3404                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3405                 }
3406         }
3407
3408         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3409                 $this->onTransactionCommitOrIdle( $callback, $fname );
3410         }
3411
3412         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3413                 if ( !$this->trxLevel() && $this->getTransactionRoundId() ) {
3414                         // Start an implicit transaction similar to how query() does
3415                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3416                         $this->trxAutomatic = true;
3417                 }
3418
3419                 if ( $this->trxLevel() ) {
3420                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3421                 } else {
3422                         // No transaction is active nor will start implicitly, so make one for this callback
3423                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3424                         try {
3425                                 $callback( $this );
3426                                 $this->endAtomic( __METHOD__ );
3427                         } catch ( Exception $e ) {
3428                                 $this->cancelAtomic( __METHOD__ );
3429                                 throw $e;
3430                         }
3431                 }
3432         }
3433
3434         final public function onAtomicSectionCancel( callable $callback, $fname = __METHOD__ ) {
3435                 if ( !$this->trxLevel() || !$this->trxAtomicLevels ) {
3436                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)" );
3437                 }
3438                 $this->trxSectionCancelCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3439         }
3440
3441         /**
3442          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3443          */
3444         private function currentAtomicSectionId() {
3445                 if ( $this->trxLevel() && $this->trxAtomicLevels ) {
3446                         $levelInfo = end( $this->trxAtomicLevels );
3447
3448                         return $levelInfo[1];
3449                 }
3450
3451                 return null;
3452         }
3453
3454         /**
3455          * Hoist callback ownership for callbacks in a section to a parent section.
3456          * All callbacks should have an owner that is present in trxAtomicLevels.
3457          * @param AtomicSectionIdentifier $old
3458          * @param AtomicSectionIdentifier $new
3459          */
3460         private function reassignCallbacksForSection(
3461                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3462         ) {
3463                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3464                         if ( $info[2] === $old ) {
3465                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3466                         }
3467                 }
3468                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3469                         if ( $info[2] === $old ) {
3470                                 $this->trxIdleCallbacks[$key][2] = $new;
3471                         }
3472                 }
3473                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3474                         if ( $info[2] === $old ) {
3475                                 $this->trxEndCallbacks[$key][2] = $new;
3476                         }
3477                 }
3478                 foreach ( $this->trxSectionCancelCallbacks as $key => $info ) {
3479                         if ( $info[2] === $old ) {
3480                                 $this->trxSectionCancelCallbacks[$key][2] = $new;
3481                         }
3482                 }
3483         }
3484
3485         /**
3486          * Update callbacks that were owned by cancelled atomic sections.
3487          *
3488          * Callbacks for "on commit" should never be run if they're owned by a
3489          * section that won't be committed.
3490          *
3491          * Callbacks for "on resolution" need to reflect that the section was
3492          * rolled back, even if the transaction as a whole commits successfully.
3493          *
3494          * Callbacks for "on section cancel" should already have been consumed,
3495          * but errors during the cancellation itself can prevent that while still
3496          * destroying the section. Hoist any such callbacks to the new top section,
3497          * which we assume will itself have to be cancelled or rolled back to
3498          * resolve the error.
3499          *
3500          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3501          * @param AtomicSectionIdentifier|null $newSectionId New top section ID.
3502          * @throws UnexpectedValueException
3503          */
3504         private function modifyCallbacksForCancel(
3505                 array $sectionIds, AtomicSectionIdentifier $newSectionId = null
3506         ) {
3507                 // Cancel the "on commit" callbacks owned by this savepoint
3508                 $this->trxIdleCallbacks = array_filter(
3509                         $this->trxIdleCallbacks,
3510                         function ( $entry ) use ( $sectionIds ) {
3511                                 return !in_array( $entry[2], $sectionIds, true );
3512                         }
3513                 );
3514                 $this->trxPreCommitCallbacks = array_filter(
3515                         $this->trxPreCommitCallbacks,
3516                         function ( $entry ) use ( $sectionIds ) {
3517                                 return !in_array( $entry[2], $sectionIds, true );
3518                         }
3519                 );
3520                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3521                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3522                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3523                                 $callback = $entry[0];
3524                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3525                                         // @phan-suppress-next-line PhanInfiniteRecursion, PhanUndeclaredInvokeInCallable
3526                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3527                                 };
3528                                 // This "on resolution" callback no longer belongs to a section.
3529                                 $this->trxEndCallbacks[$key][2] = null;
3530                         }
3531                 }
3532                 // Hoist callback ownership for section cancel callbacks to the new top section
3533                 foreach ( $this->trxSectionCancelCallbacks as $key => $entry ) {
3534                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3535                                 $this->trxSectionCancelCallbacks[$key][2] = $newSectionId;
3536                         }
3537                 }
3538         }
3539
3540         final public function setTransactionListener( $name, callable $callback = null ) {
3541                 if ( $callback ) {
3542                         $this->trxRecurringCallbacks[$name] = $callback;
3543                 } else {
3544                         unset( $this->trxRecurringCallbacks[$name] );
3545                 }
3546         }
3547
3548         /**
3549          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3550          *
3551          * This method should not be used outside of Database/LoadBalancer
3552          *
3553          * @param bool $suppress
3554          * @since 1.28
3555          */
3556         final public function setTrxEndCallbackSuppression( $suppress ) {
3557                 $this->trxEndCallbacksSuppressed = $suppress;
3558         }
3559
3560         /**
3561          * Actually consume and run any "on transaction idle/resolution" callbacks.
3562          *
3563          * This method should not be used outside of Database/LoadBalancer
3564          *
3565          * @param int $trigger IDatabase::TRIGGER_* constant
3566          * @return int Number of callbacks attempted
3567          * @since 1.20
3568          * @throws Exception
3569          */
3570         public function runOnTransactionIdleCallbacks( $trigger ) {
3571                 if ( $this->trxLevel() ) { // sanity
3572                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open' );
3573                 }
3574
3575                 if ( $this->trxEndCallbacksSuppressed ) {
3576                         return 0;
3577                 }
3578
3579                 $count = 0;
3580                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3581                 /** @var Exception $e */
3582                 $e = null; // first exception
3583                 do { // callbacks may add callbacks :)
3584                         $callbacks = array_merge(
3585                                 $this->trxIdleCallbacks,
3586                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3587                         );
3588                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3589                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3590
3591                         // Only run trxSectionCancelCallbacks on rollback, not commit.
3592                         // But always consume them.
3593                         if ( $trigger === self::TRIGGER_ROLLBACK ) {
3594                                 $callbacks = array_merge( $callbacks, $this->trxSectionCancelCallbacks );
3595                         }
3596                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3597
3598                         foreach ( $callbacks as $callback ) {
3599                                 ++$count;
3600                                 list( $phpCallback ) = $callback;
3601                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3602                                 try {
3603                                         // @phan-suppress-next-line PhanParamTooManyCallable
3604                                         call_user_func( $phpCallback, $trigger, $this );
3605                                 } catch ( Exception $ex ) {
3606                                         call_user_func( $this->errorLogger, $ex );
3607                                         $e = $e ?: $ex;
3608                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3609                                         // their transactions are ended so other callbacks don't fail
3610                                         if ( $this->trxLevel() ) {
3611                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3612                                         }
3613                                 } finally {
3614                                         if ( $autoTrx ) {
3615                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3616                                         } else {
3617                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3618                                         }
3619                                 }
3620                         }
3621                 } while ( count( $this->trxIdleCallbacks ) );
3622
3623                 if ( $e instanceof Exception ) {
3624                         throw $e; // re-throw any first exception
3625                 }
3626
3627                 return $count;
3628         }
3629
3630         /**
3631          * Actually consume and run any "on transaction pre-commit" callbacks.
3632          *
3633          * This method should not be used outside of Database/LoadBalancer
3634          *
3635          * @since 1.22
3636          * @return int Number of callbacks attempted
3637          * @throws Exception
3638          */
3639         public function runOnTransactionPreCommitCallbacks() {
3640                 $count = 0;
3641
3642                 $e = null; // first exception
3643                 do { // callbacks may add callbacks :)
3644                         $callbacks = $this->trxPreCommitCallbacks;
3645                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3646                         foreach ( $callbacks as $callback ) {
3647                                 try {
3648                                         ++$count;
3649                                         list( $phpCallback ) = $callback;
3650                                         // @phan-suppress-next-line PhanUndeclaredInvokeInCallable
3651                                         $phpCallback( $this );
3652                                 } catch ( Exception $ex ) {
3653                                         ( $this->errorLogger )( $ex );
3654                                         $e = $e ?: $ex;
3655                                 }
3656                         }
3657                 } while ( count( $this->trxPreCommitCallbacks ) );
3658
3659                 if ( $e instanceof Exception ) {
3660                         throw $e; // re-throw any first exception
3661                 }
3662
3663                 return $count;
3664         }
3665
3666         /**
3667          * Actually run any "atomic section cancel" callbacks.
3668          *
3669          * @param int $trigger IDatabase::TRIGGER_* constant
3670          * @param AtomicSectionIdentifier[]|null $sectionIds Section IDs to cancel,
3671          *  null on transaction rollback
3672          */
3673         private function runOnAtomicSectionCancelCallbacks(
3674                 $trigger, array $sectionIds = null
3675         ) {
3676                 /** @var Exception|Throwable $e */
3677                 $e = null; // first exception
3678
3679                 $notCancelled = [];
3680                 do {
3681                         $callbacks = $this->trxSectionCancelCallbacks;
3682                         $this->trxSectionCancelCallbacks = []; // consumed (recursion guard)
3683                         foreach ( $callbacks as $entry ) {
3684                                 if ( $sectionIds === null || in_array( $entry[2], $sectionIds, true ) ) {
3685                                         try {
3686                                                 // @phan-suppress-next-line PhanUndeclaredInvokeInCallable
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                 $flags = self::QUERY_IGNORE_DBO_TRX | self::QUERY_SILENCE_ERRORS;
4283                 $ok = ( $this->query( self::$PING_QUERY, __METHOD__, $flags ) !== false );
4284                 if ( $ok ) {
4285                         $rtt = $this->lastRoundTripEstimate;
4286                 }
4287
4288                 return $ok;
4289         }
4290
4291         /**
4292          * Close any existing (dead) database connection and open a new connection
4293          *
4294          * @param string $fname
4295          * @return bool True if new connection is opened successfully, false if error
4296          */
4297         protected function replaceLostConnection( $fname ) {
4298                 $this->closeConnection();
4299                 $this->conn = null;
4300
4301                 $this->handleSessionLossPreconnect();
4302
4303                 try {
4304                         $this->open(
4305                                 $this->server,
4306                                 $this->user,
4307                                 $this->password,
4308                                 $this->currentDomain->getDatabase(),
4309                                 $this->currentDomain->getSchema(),
4310                                 $this->tablePrefix()
4311                         );
4312                         $this->lastPing = microtime( true );
4313                         $ok = true;
4314
4315                         $this->connLogger->warning(
4316                                 $fname . ': lost connection to {dbserver}; reconnected',
4317                                 [
4318                                         'dbserver' => $this->getServer(),
4319                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4320                                 ]
4321                         );
4322                 } catch ( DBConnectionError $e ) {
4323                         $ok = false;
4324
4325                         $this->connLogger->error(
4326                                 $fname . ': lost connection to {dbserver} permanently',
4327                                 [ 'dbserver' => $this->getServer() ]
4328                         );
4329                 }
4330
4331                 $this->handleSessionLossPostconnect();
4332
4333                 return $ok;
4334         }
4335
4336         public function getSessionLagStatus() {
4337                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4338         }
4339
4340         /**
4341          * Get the replica DB lag when the current transaction started
4342          *
4343          * This is useful when transactions might use snapshot isolation
4344          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4345          * is this lag plus transaction duration. If they don't, it is still
4346          * safe to be pessimistic. This returns null if there is no transaction.
4347          *
4348          * This returns null if the lag status for this transaction was not yet recorded.
4349          *
4350          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4351          * @since 1.27
4352          */
4353         final protected function getRecordedTransactionLagStatus() {
4354                 return ( $this->trxLevel() && $this->trxReplicaLag !== null )
4355                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4356                         : null;
4357         }
4358
4359         /**
4360          * Get a replica DB lag estimate for this server
4361          *
4362          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4363          * @since 1.27
4364          */
4365         protected function getApproximateLagStatus() {
4366                 return [
4367                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4368                         'since' => microtime( true )
4369                 ];
4370         }
4371
4372         /**
4373          * Merge the result of getSessionLagStatus() for several DBs
4374          * using the most pessimistic values to estimate the lag of
4375          * any data derived from them in combination
4376          *
4377          * This is information is useful for caching modules
4378          *
4379          * @see WANObjectCache::set()
4380          * @see WANObjectCache::getWithSetCallback()
4381          *
4382          * @param IDatabase $db1
4383          * @param IDatabase|null $db2 [optional]
4384          * @return array Map of values:
4385          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4386          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4387          *   - pending: whether any of the DBs have uncommitted changes
4388          * @throws DBError
4389          * @since 1.27
4390          */
4391         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4392                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4393                 foreach ( func_get_args() as $db ) {
4394                         /** @var IDatabase $db */
4395                         $status = $db->getSessionLagStatus();
4396                         if ( $status['lag'] === false ) {
4397                                 $res['lag'] = false;
4398                         } elseif ( $res['lag'] !== false ) {
4399                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4400                         }
4401                         $res['since'] = min( $res['since'], $status['since'] );
4402                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4403                 }
4404
4405                 return $res;
4406         }
4407
4408         public function getLag() {
4409                 if ( $this->getLBInfo( 'master' ) ) {
4410                         return 0; // this is the master
4411                 } elseif ( $this->getLBInfo( 'is static' ) ) {
4412                         return 0; // static dataset
4413                 }
4414
4415                 return $this->doGetLag();
4416         }
4417
4418         protected function doGetLag() {
4419                 return 0;
4420         }
4421
4422         public function maxListLen() {
4423                 return 0;
4424         }
4425
4426         public function encodeBlob( $b ) {
4427                 return $b;
4428         }
4429
4430         public function decodeBlob( $b ) {
4431                 if ( $b instanceof Blob ) {
4432                         $b = $b->fetch();
4433                 }
4434                 return $b;
4435         }
4436
4437         public function setSessionOptions( array $options ) {
4438         }
4439
4440         public function sourceFile(
4441                 $filename,
4442                 callable $lineCallback = null,
4443                 callable $resultCallback = null,
4444                 $fname = false,
4445                 callable $inputCallback = null
4446         ) {
4447                 AtEase::suppressWarnings();
4448                 $fp = fopen( $filename, 'r' );
4449                 AtEase::restoreWarnings();
4450
4451                 if ( $fp === false ) {
4452                         throw new RuntimeException( "Could not open \"{$filename}\"" );
4453                 }
4454
4455                 if ( !$fname ) {
4456                         $fname = __METHOD__ . "( $filename )";
4457                 }
4458
4459                 try {
4460                         $error = $this->sourceStream(
4461                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4462                 } catch ( Exception $e ) {
4463                         fclose( $fp );
4464                         throw $e;
4465                 }
4466
4467                 fclose( $fp );
4468
4469                 return $error;
4470         }
4471
4472         public function setSchemaVars( $vars ) {
4473                 $this->schemaVars = is_array( $vars ) ? $vars : null;
4474         }
4475
4476         public function sourceStream(
4477                 $fp,
4478                 callable $lineCallback = null,
4479                 callable $resultCallback = null,
4480                 $fname = __METHOD__,
4481                 callable $inputCallback = null
4482         ) {
4483                 $delimiterReset = new ScopedCallback(
4484                         function ( $delimiter ) {
4485                                 $this->delimiter = $delimiter;
4486                         },
4487                         [ $this->delimiter ]
4488                 );
4489                 $cmd = '';
4490
4491                 while ( !feof( $fp ) ) {
4492                         if ( $lineCallback ) {
4493                                 call_user_func( $lineCallback );
4494                         }
4495
4496                         $line = trim( fgets( $fp ) );
4497
4498                         if ( $line == '' ) {
4499                                 continue;
4500                         }
4501
4502                         if ( $line[0] == '-' && $line[1] == '-' ) {
4503                                 continue;
4504                         }
4505
4506                         if ( $cmd != '' ) {
4507                                 $cmd .= ' ';
4508                         }
4509
4510                         $done = $this->streamStatementEnd( $cmd, $line );
4511
4512                         $cmd .= "$line\n";
4513
4514                         if ( $done || feof( $fp ) ) {
4515                                 $cmd = $this->replaceVars( $cmd );
4516
4517                                 if ( $inputCallback ) {
4518                                         $callbackResult = $inputCallback( $cmd );
4519
4520                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4521                                                 $cmd = $callbackResult;
4522                                         }
4523                                 }
4524
4525                                 if ( $cmd ) {
4526                                         $res = $this->query( $cmd, $fname );
4527
4528                                         if ( $resultCallback ) {
4529                                                 $resultCallback( $res, $this );
4530                                         }
4531
4532                                         if ( $res === false ) {
4533                                                 $err = $this->lastError();
4534
4535                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4536                                         }
4537                                 }
4538                                 $cmd = '';
4539                         }
4540                 }
4541
4542                 ScopedCallback::consume( $delimiterReset );
4543                 return true;
4544         }
4545
4546         /**
4547          * Called by sourceStream() to check if we've reached a statement end
4548          *
4549          * @param string &$sql SQL assembled so far
4550          * @param string &$newLine New line about to be added to $sql
4551          * @return bool Whether $newLine contains end of the statement
4552          */
4553         public function streamStatementEnd( &$sql, &$newLine ) {
4554                 if ( $this->delimiter ) {
4555                         $prev = $newLine;
4556                         $newLine = preg_replace(
4557                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4558                         if ( $newLine != $prev ) {
4559                                 return true;
4560                         }
4561                 }
4562
4563                 return false;
4564         }
4565
4566         /**
4567          * Database independent variable replacement. Replaces a set of variables
4568          * in an SQL statement with their contents as given by $this->getSchemaVars().
4569          *
4570          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4571          *
4572          * - '{$var}' should be used for text and is passed through the database's
4573          *   addQuotes method.
4574          * - `{$var}` should be used for identifiers (e.g. table and database names).
4575          *   It is passed through the database's addIdentifierQuotes method which
4576          *   can be overridden if the database uses something other than backticks.
4577          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4578          *   database's tableName method.
4579          * - / *i* / passes the name that follows through the database's indexName method.
4580          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4581          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4582          *
4583          * @param string $ins SQL statement to replace variables in
4584          * @return string The new SQL statement with variables replaced
4585          */
4586         protected function replaceVars( $ins ) {
4587                 $vars = $this->getSchemaVars();
4588                 return preg_replace_callback(
4589                         '!
4590                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4591                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4592                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4593                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4594                         !x',
4595                         function ( $m ) use ( $vars ) {
4596                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4597                                 // check for both nonexistent keys *and* the empty string.
4598                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4599                                         if ( $m[1] === 'i' ) {
4600                                                 return $this->indexName( $m[2] );
4601                                         } else {
4602                                                 return $this->tableName( $m[2] );
4603                                         }
4604                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4605                                         return $this->addQuotes( $vars[$m[3]] );
4606                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4607                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4608                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4609                                         return $vars[$m[5]];
4610                                 } else {
4611                                         return $m[0];
4612                                 }
4613                         },
4614                         $ins
4615                 );
4616         }
4617
4618         /**
4619          * Get schema variables. If none have been set via setSchemaVars(), then
4620          * use some defaults from the current object.
4621          *
4622          * @return array
4623          */
4624         protected function getSchemaVars() {
4625                 return $this->schemaVars ?? $this->getDefaultSchemaVars();
4626         }
4627
4628         /**
4629          * Get schema variables to use if none have been set via setSchemaVars().
4630          *
4631          * Override this in derived classes to provide variables for tables.sql
4632          * and SQL patch files.
4633          *
4634          * @return array
4635          */
4636         protected function getDefaultSchemaVars() {
4637                 return [];
4638         }
4639
4640         public function lockIsFree( $lockName, $method ) {
4641                 // RDBMs methods for checking named locks may or may not count this thread itself.
4642                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4643                 // the behavior choosen by the interface for this method.
4644                 return !isset( $this->sessionNamedLocks[$lockName] );
4645         }
4646
4647         public function lock( $lockName, $method, $timeout = 5 ) {
4648                 $this->sessionNamedLocks[$lockName] = 1;
4649
4650                 return true;
4651         }
4652
4653         public function unlock( $lockName, $method ) {
4654                 unset( $this->sessionNamedLocks[$lockName] );
4655
4656                 return true;
4657         }
4658
4659         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4660                 if ( $this->writesOrCallbacksPending() ) {
4661                         // This only flushes transactions to clear snapshots, not to write data
4662                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4663                         throw new DBUnexpectedError(
4664                                 $this,
4665                                 "$fname: Cannot flush pre-lock snapshot; " .
4666                                 "writes from transaction {$this->trxFname} are still pending ($fnames)"
4667                         );
4668                 }
4669
4670                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4671                         return null;
4672                 }
4673
4674                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4675                         if ( $this->trxLevel() ) {
4676                                 // There is a good chance an exception was thrown, causing any early return
4677                                 // from the caller. Let any error handler get a chance to issue rollback().
4678                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4679                                 $this->onTransactionResolution(
4680                                         function () use ( $lockKey, $fname ) {
4681                                                 $this->unlock( $lockKey, $fname );
4682                                         },
4683                                         $fname
4684                                 );
4685                         } else {
4686                                 $this->unlock( $lockKey, $fname );
4687                         }
4688                 } );
4689
4690                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4691
4692                 return $unlocker;
4693         }
4694
4695         public function namedLocksEnqueue() {
4696                 return false;
4697         }
4698
4699         public function tableLocksHaveTransactionScope() {
4700                 return true;
4701         }
4702
4703         final public function lockTables( array $read, array $write, $method ) {
4704                 if ( $this->writesOrCallbacksPending() ) {
4705                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending" );
4706                 }
4707
4708                 if ( $this->tableLocksHaveTransactionScope() ) {
4709                         $this->startAtomic( $method );
4710                 }
4711
4712                 return $this->doLockTables( $read, $write, $method );
4713         }
4714
4715         /**
4716          * Helper function for lockTables() that handles the actual table locking
4717          *
4718          * @param array $read Array of tables to lock for read access
4719          * @param array $write Array of tables to lock for write access
4720          * @param string $method Name of caller
4721          * @return true
4722          */
4723         protected function doLockTables( array $read, array $write, $method ) {
4724                 return true;
4725         }
4726
4727         final public function unlockTables( $method ) {
4728                 if ( $this->tableLocksHaveTransactionScope() ) {
4729                         $this->endAtomic( $method );
4730
4731                         return true; // locks released on COMMIT/ROLLBACK
4732                 }
4733
4734                 return $this->doUnlockTables( $method );
4735         }
4736
4737         /**
4738          * Helper function for unlockTables() that handles the actual table unlocking
4739          *
4740          * @param string $method Name of caller
4741          * @return true
4742          */
4743         protected function doUnlockTables( $method ) {
4744                 return true;
4745         }
4746
4747         /**
4748          * Delete a table
4749          * @param string $tableName
4750          * @param string $fName
4751          * @return bool|IResultWrapper
4752          * @since 1.18
4753          */
4754         public function dropTable( $tableName, $fName = __METHOD__ ) {
4755                 if ( !$this->tableExists( $tableName, $fName ) ) {
4756                         return false;
4757                 }
4758                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4759
4760                 return $this->query( $sql, $fName );
4761         }
4762
4763         public function getInfinity() {
4764                 return 'infinity';
4765         }
4766
4767         public function encodeExpiry( $expiry ) {
4768                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4769                         ? $this->getInfinity()
4770                         : $this->timestamp( $expiry );
4771         }
4772
4773         public function decodeExpiry( $expiry, $format = TS_MW ) {
4774                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4775                         return 'infinity';
4776                 }
4777
4778                 return ConvertibleTimestamp::convert( $format, $expiry );
4779         }
4780
4781         public function setBigSelects( $value = true ) {
4782                 // no-op
4783         }
4784
4785         public function isReadOnly() {
4786                 return ( $this->getReadOnlyReason() !== false );
4787         }
4788
4789         /**
4790          * @return string|bool Reason this DB is read-only or false if it is not
4791          */
4792         protected function getReadOnlyReason() {
4793                 $reason = $this->getLBInfo( 'readOnlyReason' );
4794                 if ( is_string( $reason ) ) {
4795                         return $reason;
4796                 } elseif ( $this->getLBInfo( 'replica' ) ) {
4797                         return "Server is configured in the role of a read-only replica database.";
4798                 }
4799
4800                 return false;
4801         }
4802
4803         public function setTableAliases( array $aliases ) {
4804                 $this->tableAliases = $aliases;
4805         }
4806
4807         public function setIndexAliases( array $aliases ) {
4808                 $this->indexAliases = $aliases;
4809         }
4810
4811         /**
4812          * @param int $field
4813          * @param int $flags
4814          * @return bool
4815          * @since 1.34
4816          */
4817         final protected function fieldHasBit( $field, $flags ) {
4818                 return ( ( $field & $flags ) === $flags );
4819         }
4820
4821         /**
4822          * Get the underlying binding connection handle
4823          *
4824          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4825          * This catches broken callers than catch and ignore disconnection exceptions.
4826          * Unlike checking isOpen(), this is safe to call inside of open().
4827          *
4828          * @return mixed
4829          * @throws DBUnexpectedError
4830          * @since 1.26
4831          */
4832         protected function getBindingHandle() {
4833                 if ( !$this->conn ) {
4834                         throw new DBUnexpectedError(
4835                                 $this,
4836                                 'DB connection was already closed or the connection dropped'
4837                         );
4838                 }
4839
4840                 return $this->conn;
4841         }
4842
4843         public function __toString() {
4844                 // spl_object_id is PHP >= 7.2
4845                 $id = function_exists( 'spl_object_id' )
4846                         ? spl_object_id( $this )
4847                         : spl_object_hash( $this );
4848
4849                 $description = $this->getType() . ' object #' . $id;
4850                 if ( is_resource( $this->conn ) ) {
4851                         $description .= ' (' . (string)$this->conn . ')'; // "resource id #<ID>"
4852                 } elseif ( is_object( $this->conn ) ) {
4853                         // spl_object_id is PHP >= 7.2
4854                         $handleId = function_exists( 'spl_object_id' )
4855                                 ? spl_object_id( $this->conn )
4856                                 : spl_object_hash( $this->conn );
4857                         $description .= " (handle id #$handleId)";
4858                 }
4859
4860                 return $description;
4861         }
4862
4863         /**
4864          * Make sure that copies do not share the same client binding handle
4865          * @throws DBConnectionError
4866          */
4867         public function __clone() {
4868                 $this->connLogger->warning(
4869                         "Cloning " . static::class . " is not recommended; forking connection",
4870                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
4871                 );
4872
4873                 if ( $this->isOpen() ) {
4874                         // Open a new connection resource without messing with the old one
4875                         $this->conn = null;
4876                         $this->trxEndCallbacks = []; // don't copy
4877                         $this->trxSectionCancelCallbacks = []; // don't copy
4878                         $this->handleSessionLossPreconnect(); // no trx or locks anymore
4879                         $this->open(
4880                                 $this->server,
4881                                 $this->user,
4882                                 $this->password,
4883                                 $this->currentDomain->getDatabase(),
4884                                 $this->currentDomain->getSchema(),
4885                                 $this->tablePrefix()
4886                         );
4887                         $this->lastPing = microtime( true );
4888                 }
4889         }
4890
4891         /**
4892          * Called by serialize. Throw an exception when DB connection is serialized.
4893          * This causes problems on some database engines because the connection is
4894          * not restored on unserialize.
4895          */
4896         public function __sleep() {
4897                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4898                         'the connection is not restored on wakeup' );
4899         }
4900
4901         /**
4902          * Run a few simple sanity checks and close dangling connections
4903          */
4904         public function __destruct() {
4905                 if ( $this->trxLevel() && $this->trxDoneWrites ) {
4906                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})" );
4907                 }
4908
4909                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4910                 if ( $danglingWriters ) {
4911                         $fnames = implode( ', ', $danglingWriters );
4912                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)" );
4913                 }
4914
4915                 if ( $this->conn ) {
4916                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4917                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4918                         AtEase::suppressWarnings();
4919                         $this->closeConnection();
4920                         AtEase::restoreWarnings();
4921                         $this->conn = null;
4922                 }
4923         }
4924 }
4925
4926 /**
4927  * @deprecated since 1.28
4928  */
4929 class_alias( Database::class, 'DatabaseBase' );
4930
4931 /**
4932  * @deprecated since 1.29
4933  */
4934 class_alias( Database::class, 'Database' );