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;
  34 use BagOStuff;
  35 use HashBagOStuff;
  36 use LogicException;
  37 use InvalidArgumentException;
  38 use UnexpectedValueException;
  39 use Exception;
  40 use RuntimeException;
  41
  42 /**
  43  * Relational database abstraction object
  44  *
  45  * @ingroup Database
  46  * @since 1.28
  47  */
  48 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  49         /** Number of times to re-try an operation in case of deadlock */
  50         const DEADLOCK_TRIES = 4;
  51         /** Minimum time to wait before retry, in microseconds */
  52         const DEADLOCK_DELAY_MIN = 500000;
  53         /** Maximum time to wait before retry */
  54         const DEADLOCK_DELAY_MAX = 1500000;
  55
  56         /** How long before it is worth doing a dummy query to test the connection */
  57         const PING_TTL = 1.0;
  58         const PING_QUERY = 'SELECT 1 AS ping';
  59
  60         const TINY_WRITE_SEC = 0.010;
  61         const SLOW_WRITE_SEC = 0.500;
  62         const SMALL_WRITE_ROWS = 100;
  63
  64         /** @var string Whether lock granularity is on the level of the entire database */
  65         const ATTR_DB_LEVEL_LOCKING = 'db-level-locking';
  66
  67         /** @var int New Database instance will not be connected yet when returned */
  68         const NEW_UNCONNECTED = 0;
  69         /** @var int New Database instance will already be connected when returned */
  70         const NEW_CONNECTED = 1;
  71
  72         /** @var string SQL query */
  73         protected $lastQuery = '';
  74         /** @var float|bool UNIX timestamp of last write query */
  75         protected $lastWriteTime = false;
  76         /** @var string|bool */
  77         protected $phpError = false;
  78         /** @var string Server that this instance is currently connected to */
  79         protected $server;
  80         /** @var string User that this instance is currently connected under the name of */
  81         protected $user;
  82         /** @var string Password used to establish the current connection */
  83         protected $password;
  84         /** @var array[] Map of (table => (dbname, schema, prefix) map) */
  85         protected $tableAliases = [];
  86         /** @var string[] Map of (index alias => index) */
  87         protected $indexAliases = [];
  88         /** @var bool Whether this PHP instance is for a CLI script */
  89         protected $cliMode;
  90         /** @var string Agent name for query profiling */
  91         protected $agent;
  92         /** @var array Parameters used by initConnection() to establish a connection */
  93         protected $connectionParams = [];
  94         /** @var BagOStuff APC cache */
  95         protected $srvCache;
  96         /** @var LoggerInterface */
  97         protected $connLogger;
  98         /** @var LoggerInterface */
  99         protected $queryLogger;
 100         /** @var callable Error logging callback */
 101         protected $errorLogger;
 102         /** @var callable Deprecation logging callback */
 103         protected $deprecationLogger;
 104
 105         /** @var resource|null Database connection */
 106         protected $conn = null;
 107         /** @var bool */
 108         protected $opened = false;
 109
 110         /** @var array[] List of (callable, method name, atomic section id) */
 111         protected $trxIdleCallbacks = [];
 112         /** @var array[] List of (callable, method name, atomic section id) */
 113         protected $trxPreCommitCallbacks = [];
 114         /** @var array[] List of (callable, method name, atomic section id) */
 115         protected $trxEndCallbacks = [];
 116         /** @var callable[] Map of (name => callable) */
 117         protected $trxRecurringCallbacks = [];
 118         /** @var bool Whether to suppress triggering of transaction end callbacks */
 119         protected $trxEndCallbacksSuppressed = false;
 120
 121         /** @var int */
 122         protected $flags;
 123         /** @var array */
 124         protected $lbInfo = [];
 125         /** @var array|bool */
 126         protected $schemaVars = false;
 127         /** @var array */
 128         protected $sessionVars = [];
 129         /** @var array|null */
 130         protected $preparedArgs;
 131         /** @var string|bool|null Stashed value of html_errors INI setting */
 132         protected $htmlErrors;
 133         /** @var string */
 134         protected $delimiter = ';';
 135         /** @var DatabaseDomain */
 136         protected $currentDomain;
 137         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 138         protected $affectedRowCount;
 139
 140         /**
 141          * @var int Transaction status
 142          */
 143         protected $trxStatus = self::STATUS_TRX_NONE;
 144         /**
 145          * @var Exception|null The last error that caused the status to become STATUS_TRX_ERROR
 146          */
 147         protected $trxStatusCause;
 148         /**
 149          * @var array|null If wasKnownStatementRollbackError() prevented trxStatus from being set,
 150          *  the relevant details are stored here.
 151          */
 152         protected $trxStatusIgnoredCause;
 153         /**
 154          * Either 1 if a transaction is active or 0 otherwise.
 155          * The other Trx fields may not be meaningfull if this is 0.
 156          *
 157          * @var int
 158          */
 159         protected $trxLevel = 0;
 160         /**
 161          * Either a short hexidecimal string if a transaction is active or ""
 162          *
 163          * @var string
 164          * @see Database::trxLevel
 165          */
 166         protected $trxShortId = '';
 167         /**
 168          * The UNIX time that the transaction started. Callers can assume that if
 169          * snapshot isolation is used, then the data is *at least* up to date to that
 170          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 171          *
 172          * @var float|null
 173          * @see Database::trxLevel
 174          */
 175         private $trxTimestamp = null;
 176         /** @var float Lag estimate at the time of BEGIN */
 177         private $trxReplicaLag = null;
 178         /**
 179          * Remembers the function name given for starting the most recent transaction via begin().
 180          * Used to provide additional context for error reporting.
 181          *
 182          * @var string
 183          * @see Database::trxLevel
 184          */
 185         private $trxFname = null;
 186         /**
 187          * Record if possible write queries were done in the last transaction started
 188          *
 189          * @var bool
 190          * @see Database::trxLevel
 191          */
 192         private $trxDoneWrites = false;
 193         /**
 194          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 195          *
 196          * @var bool
 197          * @see Database::trxLevel
 198          */
 199         private $trxAutomatic = false;
 200         /**
 201          * Counter for atomic savepoint identifiers. Reset when a new transaction begins.
 202          *
 203          * @var int
 204          */
 205         private $trxAtomicCounter = 0;
 206         /**
 207          * Array of levels of atomicity within transactions
 208          *
 209          * @var array List of (name, unique ID, savepoint ID)
 210          */
 211         private $trxAtomicLevels = [];
 212         /**
 213          * Record if the current transaction was started implicitly by Database::startAtomic
 214          *
 215          * @var bool
 216          */
 217         private $trxAutomaticAtomic = false;
 218         /**
 219          * Track the write query callers of the current transaction
 220          *
 221          * @var string[]
 222          */
 223         private $trxWriteCallers = [];
 224         /**
 225          * @var float Seconds spent in write queries for the current transaction
 226          */
 227         private $trxWriteDuration = 0.0;
 228         /**
 229          * @var int Number of write queries for the current transaction
 230          */
 231         private $trxWriteQueryCount = 0;
 232         /**
 233          * @var int Number of rows affected by write queries for the current transaction
 234          */
 235         private $trxWriteAffectedRows = 0;
 236         /**
 237          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 238          */
 239         private $trxWriteAdjDuration = 0.0;
 240         /**
 241          * @var int Number of write queries counted in trxWriteAdjDuration
 242          */
 243         private $trxWriteAdjQueryCount = 0;
 244         /**
 245          * @var float RTT time estimate
 246          */
 247         private $rttEstimate = 0.0;
 248
 249         /** @var array Map of (name => 1) for locks obtained via lock() */
 250         private $namedLocksHeld = [];
 251         /** @var array Map of (table name => 1) for TEMPORARY tables */
 252         protected $sessionTempTables = [];
 253
 254         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 255         private $lazyMasterHandle;
 256
 257         /** @var float UNIX timestamp */
 258         protected $lastPing = 0.0;
 259
 260         /** @var int[] Prior flags member variable values */
 261         private $priorFlags = [];
 262
 263         /** @var mixed Class name or object With profileIn/profileOut methods */
 264         protected $profiler;
 265         /** @var TransactionProfiler */
 266         protected $trxProfiler;
 267
 268         /** @var int */
 269         protected $nonNativeInsertSelectBatchSize = 10000;
 270
 271         /** @var string Idiom used when a cancelable atomic section started the transaction */
 272         private static $NOT_APPLICABLE = 'n/a';
 273         /** @var string Prefix to the atomic section counter used to make savepoint IDs */
 274         private static $SAVEPOINT_PREFIX = 'wikimedia_rdbms_atomic';
 275
 276         /** @var int Transaction is in a error state requiring a full or savepoint rollback */
 277         const STATUS_TRX_ERROR = 1;
 278         /** @var int Transaction is active and in a normal state */
 279         const STATUS_TRX_OK = 2;
 280         /** @var int No transaction is active */
 281         const STATUS_TRX_NONE = 3;
 282
 283         /**
 284          * @note exceptions for missing libraries/drivers should be thrown in initConnection()
 285          * @param array $params Parameters passed from Database::factory()
 286          */
 287         protected function __construct( array $params ) {
 288                 foreach ( [ 'host', 'user', 'password', 'dbname', 'schema', 'tablePrefix' ] as $name ) {
 289                         $this->connectionParams[$name] = $params[$name];
 290                 }
 291
 292                 $this->cliMode = $params['cliMode'];
 293                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 294                 $this->agent = str_replace( '/', '-', $params['agent'] );
 295
 296                 $this->flags = $params['flags'];
 297                 if ( $this->flags & self::DBO_DEFAULT ) {
 298                         if ( $this->cliMode ) {
 299                                 $this->flags &= ~self::DBO_TRX;
 300                         } else {
 301                                 $this->flags |= self::DBO_TRX;
 302                         }
 303                 }
 304                 // Disregard deprecated DBO_IGNORE flag (T189999)
 305                 $this->flags &= ~self::DBO_IGNORE;
 306
 307                 $this->sessionVars = $params['variables'];
 308
 309                 $this->srvCache = $params['srvCache'] ?? new HashBagOStuff();
 310
 311                 $this->profiler = $params['profiler'];
 312                 $this->trxProfiler = $params['trxProfiler'];
 313                 $this->connLogger = $params['connLogger'];
 314                 $this->queryLogger = $params['queryLogger'];
 315                 $this->errorLogger = $params['errorLogger'];
 316                 $this->deprecationLogger = $params['deprecationLogger'];
 317
 318                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 319                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 320                 }
 321
 322                 // Set initial dummy domain until open() sets the final DB/prefix
 323                 $this->currentDomain = new DatabaseDomain(
 324                         $params['dbname'] != '' ? $params['dbname'] : null,
 325                         $params['schema'] != '' ? $params['schema'] : null,
 326                         $params['tablePrefix']
 327                 );
 328         }
 329
 330         /**
 331          * Initialize the connection to the database over the wire (or to local files)
 332          *
 333          * @throws LogicException
 334          * @throws InvalidArgumentException
 335          * @throws DBConnectionError
 336          * @since 1.31
 337          */
 338         final public function initConnection() {
 339                 if ( $this->isOpen() ) {
 340                         throw new LogicException( __METHOD__ . ': already connected.' );
 341                 }
 342                 // Establish the connection
 343                 $this->doInitConnection();
 344         }
 345
 346         /**
 347          * Actually connect to the database over the wire (or to local files)
 348          *
 349          * @throws InvalidArgumentException
 350          * @throws DBConnectionError
 351          * @since 1.31
 352          */
 353         protected function doInitConnection() {
 354                 if ( strlen( $this->connectionParams['user'] ) ) {
 355                         $this->open(
 356                                 $this->connectionParams['host'],
 357                                 $this->connectionParams['user'],
 358                                 $this->connectionParams['password'],
 359                                 $this->connectionParams['dbname'],
 360                                 $this->connectionParams['schema'],
 361                                 $this->connectionParams['tablePrefix']
 362                         );
 363                 } else {
 364                         throw new InvalidArgumentException( "No database user provided." );
 365                 }
 366         }
 367
 368         /**
 369          * Open a new connection to the database (closing any existing one)
 370          *
 371          * @param string $server Database server host
 372          * @param string $user Database user name
 373          * @param string $password Database user password
 374          * @param string $dbName Database name
 375          * @param string|null $schema Database schema name
 376          * @param string $tablePrefix Table prefix
 377          * @return bool
 378          * @throws DBConnectionError
 379          */
 380         abstract protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix );
 381
 382         /**
 383          * Construct a Database subclass instance given a database type and parameters
 384          *
 385          * This also connects to the database immediately upon object construction
 386          *
 387          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 388          * @param array $p Parameter map with keys:
 389          *   - host : The hostname of the DB server
 390          *   - user : The name of the database user the client operates under
 391          *   - password : The password for the database user
 392          *   - dbname : The name of the database to use where queries do not specify one.
 393          *      The database must exist or an error might be thrown. Setting this to the empty string
 394          *      will avoid any such errors and make the handle have no implicit database scope. This is
 395          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 396          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 397          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 398          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 399          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 400          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 401          *      recognized in queries. This can be used in place of schemas for handle site farms.
 402          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 403          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 404          *      flag in place UNLESS this this database simply acts as a key/value store.
 405          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 406          *      'mysqli' driver; the old one 'mysql' has been removed.
 407          *   - variables: Optional map of session variables to set after connecting. This can be
 408          *      used to adjust lock timeouts or encoding modes and the like.
 409          *   - connLogger: Optional PSR-3 logger interface instance.
 410          *   - queryLogger: Optional PSR-3 logger interface instance.
 411          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 412          *      These will be called in query(), using a simplified version of the SQL that also
 413          *      includes the agent as a SQL comment.
 414          *   - trxProfiler: Optional TransactionProfiler instance.
 415          *   - errorLogger: Optional callback that takes an Exception and logs it.
 416          *   - deprecationLogger: Optional callback that takes a string and logs it.
 417          *   - cliMode: Whether to consider the execution context that of a CLI script.
 418          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 419          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 420          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 421          * @param int $connect One of the class constants (NEW_CONNECTED, NEW_UNCONNECTED) [optional]
 422          * @return Database|null If the database driver or extension cannot be found
 423          * @throws InvalidArgumentException If the database driver or extension cannot be found
 424          * @since 1.18
 425          */
 426         final public static function factory( $dbType, $p = [], $connect = self::NEW_CONNECTED ) {
 427                 $class = self::getClass( $dbType, $p['driver'] ?? null );
 428
 429                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 430                         // Resolve some defaults for b/c
 431                         $p['host'] = $p['host'] ?? false;
 432                         $p['user'] = $p['user'] ?? false;
 433                         $p['password'] = $p['password'] ?? false;
 434                         $p['dbname'] = $p['dbname'] ?? false;
 435                         $p['flags'] = $p['flags'] ?? 0;
 436                         $p['variables'] = $p['variables'] ?? [];
 437                         $p['tablePrefix'] = $p['tablePrefix'] ?? '';
 438                         $p['schema'] = $p['schema'] ?? null;
 439                         $p['cliMode'] = $p['cliMode'] ?? ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 440                         $p['agent'] = $p['agent'] ?? '';
 441                         if ( !isset( $p['connLogger'] ) ) {
 442                                 $p['connLogger'] = new NullLogger();
 443                         }
 444                         if ( !isset( $p['queryLogger'] ) ) {
 445                                 $p['queryLogger'] = new NullLogger();
 446                         }
 447                         $p['profiler'] = $p['profiler'] ?? null;
 448                         if ( !isset( $p['trxProfiler'] ) ) {
 449                                 $p['trxProfiler'] = new TransactionProfiler();
 450                         }
 451                         if ( !isset( $p['errorLogger'] ) ) {
 452                                 $p['errorLogger'] = function ( Exception $e ) {
 453                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 454                                 };
 455                         }
 456                         if ( !isset( $p['deprecationLogger'] ) ) {
 457                                 $p['deprecationLogger'] = function ( $msg ) {
 458                                         trigger_error( $msg, E_USER_DEPRECATED );
 459                                 };
 460                         }
 461
 462                         /** @var Database $conn */
 463                         $conn = new $class( $p );
 464                         if ( $connect == self::NEW_CONNECTED ) {
 465                                 $conn->initConnection();
 466                         }
 467                 } else {
 468                         $conn = null;
 469                 }
 470
 471                 return $conn;
 472         }
 473
 474         /**
 475          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 476          * @param string|null $driver Optional name of a specific DB client driver
 477          * @return array Map of (Database::ATTRIBUTE_* constant => value) for all such constants
 478          * @throws InvalidArgumentException
 479          * @since 1.31
 480          */
 481         final public static function attributesFromType( $dbType, $driver = null ) {
 482                 static $defaults = [ self::ATTR_DB_LEVEL_LOCKING => false ];
 483
 484                 $class = self::getClass( $dbType, $driver );
 485
 486                 return call_user_func( [ $class, 'getAttributes' ] ) + $defaults;
 487         }
 488
 489         /**
 490          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 491          * @param string|null $driver Optional name of a specific DB client driver
 492          * @return string Database subclass name to use
 493          * @throws InvalidArgumentException
 494          */
 495         private static function getClass( $dbType, $driver = null ) {
 496                 // For database types with built-in support, the below maps type to IDatabase
 497                 // implementations. For types with multipe driver implementations (PHP extensions),
 498                 // an array can be used, keyed by extension name. In case of an array, the
 499                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 500                 // we auto-detect the first available driver. For types without built-in support,
 501                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 502                 static $builtinTypes = [
 503                         'mssql' => DatabaseMssql::class,
 504                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 505                         'sqlite' => DatabaseSqlite::class,
 506                         'postgres' => DatabasePostgres::class,
 507                 ];
 508
 509                 $dbType = strtolower( $dbType );
 510                 $class = false;
 511
 512                 if ( isset( $builtinTypes[$dbType] ) ) {
 513                         $possibleDrivers = $builtinTypes[$dbType];
 514                         if ( is_string( $possibleDrivers ) ) {
 515                                 $class = $possibleDrivers;
 516                         } else {
 517                                 if ( (string)$driver !== '' ) {
 518                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 519                                                 throw new InvalidArgumentException( __METHOD__ .
 520                                                         " type '$dbType' does not support driver '{$driver}'" );
 521                                         } else {
 522                                                 $class = $possibleDrivers[$driver];
 523                                         }
 524                                 } else {
 525                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 526                                                 if ( extension_loaded( $posDriver ) ) {
 527                                                         $class = $possibleClass;
 528                                                         break;
 529                                                 }
 530                                         }
 531                                 }
 532                         }
 533                 } else {
 534                         $class = 'Database' . ucfirst( $dbType );
 535                 }
 536
 537                 if ( $class === false ) {
 538                         throw new InvalidArgumentException( __METHOD__ .
 539                                 " no viable database extension found for type '$dbType'" );
 540                 }
 541
 542                 return $class;
 543         }
 544
 545         /**
 546          * @return array Map of (Database::ATTRIBUTE_* constant => value
 547          * @since 1.31
 548          */
 549         protected static function getAttributes() {
 550                 return [];
 551         }
 552
 553         /**
 554          * Set the PSR-3 logger interface to use for query logging. (The logger
 555          * interfaces for connection logging and error logging can be set with the
 556          * constructor.)
 557          *
 558          * @param LoggerInterface $logger
 559          */
 560         public function setLogger( LoggerInterface $logger ) {
 561                 $this->queryLogger = $logger;
 562         }
 563
 564         public function getServerInfo() {
 565                 return $this->getServerVersion();
 566         }
 567
 568         public function bufferResults( $buffer = null ) {
 569                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 570                 if ( $buffer !== null ) {
 571                         $buffer
 572                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 573                                 : $this->setFlag( self::DBO_NOBUFFER );
 574                 }
 575
 576                 return $res;
 577         }
 578
 579         public function trxLevel() {
 580                 return $this->trxLevel;
 581         }
 582
 583         public function trxTimestamp() {
 584                 return $this->trxLevel ? $this->trxTimestamp : null;
 585         }
 586
 587         /**
 588          * @return int One of the STATUS_TRX_* class constants
 589          * @since 1.31
 590          */
 591         public function trxStatus() {
 592                 return $this->trxStatus;
 593         }
 594
 595         public function tablePrefix( $prefix = null ) {
 596                 $old = $this->currentDomain->getTablePrefix();
 597                 if ( $prefix !== null ) {
 598                         $this->currentDomain = new DatabaseDomain(
 599                                 $this->currentDomain->getDatabase(),
 600                                 $this->currentDomain->getSchema(),
 601                                 $prefix
 602                         );
 603                 }
 604
 605                 return $old;
 606         }
 607
 608         public function dbSchema( $schema = null ) {
 609                 $old = $this->currentDomain->getSchema();
 610                 if ( $schema !== null ) {
 611                         $this->currentDomain = new DatabaseDomain(
 612                                 $this->currentDomain->getDatabase(),
 613                                 // DatabaseDomain uses null for unspecified schemas
 614                                 strlen( $schema ) ? $schema : null,
 615                                 $this->currentDomain->getTablePrefix()
 616                         );
 617                 }
 618
 619                 return (string)$old;
 620         }
 621
 622         /**
 623          * @return string Schema to use to qualify relations in queries
 624          */
 625         protected function relationSchemaQualifier() {
 626                 return $this->dbSchema();
 627         }
 628
 629         public function getLBInfo( $name = null ) {
 630                 if ( is_null( $name ) ) {
 631                         return $this->lbInfo;
 632                 } else {
 633                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 634                                 return $this->lbInfo[$name];
 635                         } else {
 636                                 return null;
 637                         }
 638                 }
 639         }
 640
 641         public function setLBInfo( $name, $value = null ) {
 642                 if ( is_null( $value ) ) {
 643                         $this->lbInfo = $name;
 644                 } else {
 645                         $this->lbInfo[$name] = $value;
 646                 }
 647         }
 648
 649         public function setLazyMasterHandle( IDatabase $conn ) {
 650                 $this->lazyMasterHandle = $conn;
 651         }
 652
 653         /**
 654          * @return IDatabase|null
 655          * @see setLazyMasterHandle()
 656          * @since 1.27
 657          */
 658         protected function getLazyMasterHandle() {
 659                 return $this->lazyMasterHandle;
 660         }
 661
 662         public function implicitGroupby() {
 663                 return true;
 664         }
 665
 666         public function implicitOrderby() {
 667                 return true;
 668         }
 669
 670         public function lastQuery() {
 671                 return $this->lastQuery;
 672         }
 673
 674         public function doneWrites() {
 675                 return (bool)$this->lastWriteTime;
 676         }
 677
 678         public function lastDoneWrites() {
 679                 return $this->lastWriteTime ?: false;
 680         }
 681
 682         public function writesPending() {
 683                 return $this->trxLevel && $this->trxDoneWrites;
 684         }
 685
 686         public function writesOrCallbacksPending() {
 687                 return $this->trxLevel && (
 688                         $this->trxDoneWrites ||
 689                         $this->trxIdleCallbacks ||
 690                         $this->trxPreCommitCallbacks ||
 691                         $this->trxEndCallbacks
 692                 );
 693         }
 694
 695         public function preCommitCallbacksPending() {
 696                 return $this->trxLevel && $this->trxPreCommitCallbacks;
 697         }
 698
 699         /**
 700          * @return string|null
 701          */
 702         final protected function getTransactionRoundId() {
 703                 // If transaction round participation is enabled, see if one is active
 704                 if ( $this->getFlag( self::DBO_TRX ) ) {
 705                         $id = $this->getLBInfo( 'trxRoundId' );
 706
 707                         return is_string( $id ) ? $id : null;
 708                 }
 709
 710                 return null;
 711         }
 712
 713         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 714                 if ( !$this->trxLevel ) {
 715                         return false;
 716                 } elseif ( !$this->trxDoneWrites ) {
 717                         return 0.0;
 718                 }
 719
 720                 switch ( $type ) {
 721                         case self::ESTIMATE_DB_APPLY:
 722                                 return $this->pingAndCalculateLastTrxApplyTime();
 723                         default: // everything
 724                                 return $this->trxWriteDuration;
 725                 }
 726         }
 727
 728         /**
 729          * @return float Time to apply writes to replicas based on trxWrite* fields
 730          */
 731         private function pingAndCalculateLastTrxApplyTime() {
 732                 $this->ping( $rtt );
 733
 734                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 735                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 736                 // For omitted queries, make them count as something at least
 737                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 738                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 739
 740                 return $applyTime;
 741         }
 742
 743         public function pendingWriteCallers() {
 744                 return $this->trxLevel ? $this->trxWriteCallers : [];
 745         }
 746
 747         public function pendingWriteRowsAffected() {
 748                 return $this->trxWriteAffectedRows;
 749         }
 750
 751         /**
 752          * List the methods that have write queries or callbacks for the current transaction
 753          *
 754          * This method should not be used outside of Database/LoadBalancer
 755          *
 756          * @return string[]
 757          * @since 1.32
 758          */
 759         public function pendingWriteAndCallbackCallers() {
 760                 $fnames = $this->pendingWriteCallers();
 761                 foreach ( [
 762                         $this->trxIdleCallbacks,
 763                         $this->trxPreCommitCallbacks,
 764                         $this->trxEndCallbacks
 765                 ] as $callbacks ) {
 766                         foreach ( $callbacks as $callback ) {
 767                                 $fnames[] = $callback[1];
 768                         }
 769                 }
 770
 771                 return $fnames;
 772         }
 773
 774         /**
 775          * @return string
 776          */
 777         private function flatAtomicSectionList() {
 778                 return array_reduce( $this->trxAtomicLevels, function ( $accum, $v ) {
 779                         return $accum === null ? $v[0] : "$accum, " . $v[0];
 780                 } );
 781         }
 782
 783         public function isOpen() {
 784                 return $this->opened;
 785         }
 786
 787         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 788                 if ( ( $flag & self::DBO_IGNORE ) ) {
 789                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 790                 }
 791
 792                 if ( $remember === self::REMEMBER_PRIOR ) {
 793                         array_push( $this->priorFlags, $this->flags );
 794                 }
 795                 $this->flags |= $flag;
 796         }
 797
 798         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 799                 if ( ( $flag & self::DBO_IGNORE ) ) {
 800                         throw new UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 801                 }
 802
 803                 if ( $remember === self::REMEMBER_PRIOR ) {
 804                         array_push( $this->priorFlags, $this->flags );
 805                 }
 806                 $this->flags &= ~$flag;
 807         }
 808
 809         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 810                 if ( !$this->priorFlags ) {
 811                         return;
 812                 }
 813
 814                 if ( $state === self::RESTORE_INITIAL ) {
 815                         $this->flags = reset( $this->priorFlags );
 816                         $this->priorFlags = [];
 817                 } else {
 818                         $this->flags = array_pop( $this->priorFlags );
 819                 }
 820         }
 821
 822         public function getFlag( $flag ) {
 823                 return (bool)( $this->flags & $flag );
 824         }
 825
 826         /**
 827          * @param string $name Class field name
 828          * @return mixed
 829          * @deprecated Since 1.28
 830          */
 831         public function getProperty( $name ) {
 832                 return $this->$name;
 833         }
 834
 835         public function getDomainID() {
 836                 return $this->currentDomain->getId();
 837         }
 838
 839         final public function getWikiID() {
 840                 return $this->getDomainID();
 841         }
 842
 843         /**
 844          * Get information about an index into an object
 845          * @param string $table Table name
 846          * @param string $index Index name
 847          * @param string $fname Calling function name
 848          * @return mixed Database-specific index description class or false if the index does not exist
 849          */
 850         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 851
 852         /**
 853          * Wrapper for addslashes()
 854          *
 855          * @param string $s String to be slashed.
 856          * @return string Slashed string.
 857          */
 858         abstract function strencode( $s );
 859
 860         /**
 861          * Set a custom error handler for logging errors during database connection
 862          */
 863         protected function installErrorHandler() {
 864                 $this->phpError = false;
 865                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 866                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 867         }
 868
 869         /**
 870          * Restore the previous error handler and return the last PHP error for this DB
 871          *
 872          * @return bool|string
 873          */
 874         protected function restoreErrorHandler() {
 875                 restore_error_handler();
 876                 if ( $this->htmlErrors !== false ) {
 877                         ini_set( 'html_errors', $this->htmlErrors );
 878                 }
 879
 880                 return $this->getLastPHPError();
 881         }
 882
 883         /**
 884          * @return string|bool Last PHP error for this DB (typically connection errors)
 885          */
 886         protected function getLastPHPError() {
 887                 if ( $this->phpError ) {
 888                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 889                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 890
 891                         return $error;
 892                 }
 893
 894                 return false;
 895         }
 896
 897         /**
 898          * Error handler for logging errors during database connection
 899          * This method should not be used outside of Database classes
 900          *
 901          * @param int $errno
 902          * @param string $errstr
 903          */
 904         public function connectionErrorLogger( $errno, $errstr ) {
 905                 $this->phpError = $errstr;
 906         }
 907
 908         /**
 909          * Create a log context to pass to PSR-3 logger functions.
 910          *
 911          * @param array $extras Additional data to add to context
 912          * @return array
 913          */
 914         protected function getLogContext( array $extras = [] ) {
 915                 return array_merge(
 916                         [
 917                                 'db_server' => $this->server,
 918                                 'db_name' => $this->getDBname(),
 919                                 'db_user' => $this->user,
 920                         ],
 921                         $extras
 922                 );
 923         }
 924
 925         final public function close() {
 926                 $exception = null; // error to throw after disconnecting
 927
 928                 if ( $this->conn ) {
 929                         // Roll back any dangling transaction first
 930                         if ( $this->trxLevel ) {
 931                                 if ( $this->trxAtomicLevels ) {
 932                                         // Cannot let incomplete atomic sections be committed
 933                                         $levels = $this->flatAtomicSectionList();
 934                                         $exception = new DBUnexpectedError(
 935                                                 $this,
 936                                                 __METHOD__ . ": atomic sections $levels are still open."
 937                                         );
 938                                 } elseif ( $this->trxAutomatic ) {
 939                                         // Only the connection manager can commit non-empty DBO_TRX transactions
 940                                         // (empty ones we can silently roll back)
 941                                         if ( $this->writesOrCallbacksPending() ) {
 942                                                 $exception = new DBUnexpectedError(
 943                                                         $this,
 944                                                         __METHOD__ .
 945                                                         ": mass commit/rollback of peer transaction required (DBO_TRX set)."
 946                                                 );
 947                                         }
 948                                 } else {
 949                                         // Manual transactions should have been committed or rolled
 950                                         // back, even if empty.
 951                                         $exception = new DBUnexpectedError(
 952                                                 $this,
 953                                                 __METHOD__ . ": transaction is still open (from {$this->trxFname})."
 954                                         );
 955                                 }
 956
 957                                 if ( $this->trxEndCallbacksSuppressed ) {
 958                                         $exception = $exception ?: new DBUnexpectedError(
 959                                                 $this,
 960                                                 __METHOD__ . ': callbacks are suppressed; cannot properly commit.'
 961                                         );
 962                                 }
 963
 964                                 // Rollback the changes and run any callbacks as needed
 965                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 966                         }
 967
 968                         // Close the actual connection in the binding handle
 969                         $closed = $this->closeConnection();
 970                         $this->conn = false;
 971                 } else {
 972                         $closed = true; // already closed; nothing to do
 973                 }
 974
 975                 $this->opened = false;
 976
 977                 // Throw any unexpected errors after having disconnected
 978                 if ( $exception instanceof Exception ) {
 979                         throw $exception;
 980                 }
 981
 982                 // Sanity check that no callbacks are dangling
 983                 $fnames = $this->pendingWriteAndCallbackCallers();
 984                 if ( $fnames ) {
 985                         throw new RuntimeException(
 986                                 "Transaction callbacks are still pending:\n" . implode( ', ', $fnames )
 987                         );
 988                 }
 989
 990                 return $closed;
 991         }
 992
 993         /**
 994          * Make sure isOpen() returns true as a sanity check
 995          *
 996          * @throws DBUnexpectedError
 997          */
 998         protected function assertOpen() {
 999                 if ( !$this->isOpen() ) {
1000                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
1001                 }
1002         }
1003
1004         /**
1005          * Closes underlying database connection
1006          * @since 1.20
1007          * @return bool Whether connection was closed successfully
1008          */
1009         abstract protected function closeConnection();
1010
1011         /**
1012          * @deprecated since 1.32
1013          * @param string $error Fallback message, if none is given by DB
1014          * @throws DBConnectionError
1015          */
1016         public function reportConnectionError( $error = 'Unknown error' ) {
1017                 call_user_func( $this->deprecationLogger, 'Use of ' . __METHOD__ . ' is deprecated.' );
1018                 throw new DBConnectionError( $this, $this->lastError() ?: $error );
1019         }
1020
1021         /**
1022          * Run a query and return a DBMS-dependent wrapper or boolean
1023          *
1024          * For SELECT queries, this returns either:
1025          *   - a) A driver-specific value/resource, only on success. This can be iterated
1026          *        over by calling fetchObject()/fetchRow() until there are no more rows.
1027          *        Alternatively, the result can be passed to resultObject() to obtain a
1028          *        ResultWrapper instance which can then be iterated over via "foreach".
1029          *   - b) False, on any query failure
1030          *
1031          * For non-SELECT queries, this returns either:
1032          *   - a) A driver-specific value/resource, only on success
1033          *   - b) True, only on success (e.g. no meaningful result other than "OK")
1034          *   - c) False, on any query failure
1035          *
1036          * @param string $sql SQL query
1037          * @return mixed|bool An object, resource, or true on success; false on failure
1038          */
1039         abstract protected function doQuery( $sql );
1040
1041         /**
1042          * Determine whether a query writes to the DB. When in doubt, this returns true.
1043          *
1044          * Main use cases:
1045          *
1046          * - Subsequent web requests should not need to wait for replication from
1047          *   the master position seen by this web request, unless this request made
1048          *   changes to the master. This is handled by ChronologyProtector by checking
1049          *   doneWrites() at the end of the request. doneWrites() returns true if any
1050          *   query set lastWriteTime; which query() does based on isWriteQuery().
1051          *
1052          * - Reject write queries to replica DBs, in query().
1053          *
1054          * @param string $sql
1055          * @return bool
1056          */
1057         protected function isWriteQuery( $sql ) {
1058                 // BEGIN and COMMIT queries are considered read queries here.
1059                 // Database backends and drivers (MySQL, MariaDB, php-mysqli) generally
1060                 // treat these as write queries, in that their results have "affected rows"
1061                 // as meta data as from writes, instead of "num rows" as from reads.
1062                 // But, we treat them as read queries because when reading data (from
1063                 // either replica or master) we use transactions to enable repeatable-read
1064                 // snapshots, which ensures we get consistent results from the same snapshot
1065                 // for all queries within a request. Use cases:
1066                 // - Treating these as writes would trigger ChronologyProtector (see method doc).
1067                 // - We use this method to reject writes to replicas, but we need to allow
1068                 //   use of transactions on replicas for read snapshots. This fine given
1069                 //   that transactions by themselves don't make changes, only actual writes
1070                 //   within the transaction matter, which we still detect.
1071                 return !preg_match(
1072                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SAVEPOINT|RELEASE|SET|SHOW|EXPLAIN|\(SELECT)\b/i',
1073                         $sql
1074                 );
1075         }
1076
1077         /**
1078          * @param string $sql
1079          * @return string|null
1080          */
1081         protected function getQueryVerb( $sql ) {
1082                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
1083         }
1084
1085         /**
1086          * Determine whether a SQL statement is sensitive to isolation level.
1087          *
1088          * A SQL statement is considered transactable if its result could vary
1089          * depending on the transaction isolation level. Operational commands
1090          * such as 'SET' and 'SHOW' are not considered to be transactable.
1091          *
1092          * Main purpose: Used by query() to decide whether to begin a transaction
1093          * before the current query (in DBO_TRX mode, on by default).
1094          *
1095          * @param string $sql
1096          * @return bool
1097          */
1098         protected function isTransactableQuery( $sql ) {
1099                 return !in_array(
1100                         $this->getQueryVerb( $sql ),
1101                         [ 'BEGIN', 'ROLLBACK', 'COMMIT', 'SET', 'SHOW', 'CREATE', 'ALTER' ],
1102                         true
1103                 );
1104         }
1105
1106         /**
1107          * @param string $sql A SQL query
1108          * @return bool Whether $sql is SQL for TEMPORARY table operation
1109          */
1110         protected function registerTempTableOperation( $sql ) {
1111                 if ( preg_match(
1112                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1113                         $sql,
1114                         $matches
1115                 ) ) {
1116                         $this->sessionTempTables[$matches[1]] = 1;
1117
1118                         return true;
1119                 } elseif ( preg_match(
1120                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1121                         $sql,
1122                         $matches
1123                 ) ) {
1124                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
1125                         unset( $this->sessionTempTables[$matches[1]] );
1126
1127                         return $isTemp;
1128                 } elseif ( preg_match(
1129                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
1130                         $sql,
1131                         $matches
1132                 ) ) {
1133                         return isset( $this->sessionTempTables[$matches[1]] );
1134                 } elseif ( preg_match(
1135                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
1136                         $sql,
1137                         $matches
1138                 ) ) {
1139                         return isset( $this->sessionTempTables[$matches[1]] );
1140                 }
1141
1142                 return false;
1143         }
1144
1145         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1146                 $this->assertTransactionStatus( $sql, $fname );
1147
1148                 # Avoid fatals if close() was called
1149                 $this->assertOpen();
1150
1151                 $priorWritesPending = $this->writesOrCallbacksPending();
1152                 $this->lastQuery = $sql;
1153
1154                 $isWrite = $this->isWriteQuery( $sql );
1155                 if ( $isWrite ) {
1156                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
1157                 } else {
1158                         $isNonTempWrite = false;
1159                 }
1160
1161                 if ( $isWrite ) {
1162                         if ( $this->getLBInfo( 'replica' ) === true ) {
1163                                 throw new DBError(
1164                                         $this,
1165                                         'Write operations are not allowed on replica database connections.'
1166                                 );
1167                         }
1168                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
1169                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
1170                         $reason = $this->getReadOnlyReason();
1171                         if ( $reason !== false ) {
1172                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
1173                         }
1174                         # Set a flag indicating that writes have been done
1175                         $this->lastWriteTime = microtime( true );
1176                 }
1177
1178                 # Add trace comment to the begin of the sql string, right after the operator.
1179                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
1180                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
1181
1182                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
1183                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
1184                         && $this->isTransactableQuery( $sql )
1185                 ) {
1186                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
1187                         $this->trxAutomatic = true;
1188                 }
1189
1190                 # Keep track of whether the transaction has write queries pending
1191                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
1192                         $this->trxDoneWrites = true;
1193                         $this->trxProfiler->transactionWritingIn(
1194                                 $this->server, $this->getDomainID(), $this->trxShortId );
1195                 }
1196
1197                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
1198                         $this->queryLogger->debug( "{$this->getDomainID()} {$commentedSql}" );
1199                 }
1200
1201                 # Send the query to the server and fetch any corresponding errors
1202                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1203                 $lastError = $this->lastError();
1204                 $lastErrno = $this->lastErrno();
1205
1206                 # Try reconnecting if the connection was lost
1207                 if ( $ret === false && $this->wasConnectionLoss() ) {
1208                         # Check if any meaningful session state was lost
1209                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
1210                         # Update session state tracking and try to restore the connection
1211                         $reconnected = $this->replaceLostConnection( __METHOD__ );
1212                         # Silently resend the query to the server if it is safe and possible
1213                         if ( $reconnected && $recoverable ) {
1214                                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
1215                                 $lastError = $this->lastError();
1216                                 $lastErrno = $this->lastErrno();
1217
1218                                 if ( $ret === false && $this->wasConnectionLoss() ) {
1219                                         # Query probably causes disconnects; reconnect and do not re-run it
1220                                         $this->replaceLostConnection( __METHOD__ );
1221                                 }
1222                         }
1223                 }
1224
1225                 if ( $ret === false ) {
1226                         if ( $this->trxLevel ) {
1227                                 if ( $this->wasKnownStatementRollbackError() ) {
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 = [ $lastError, $lastErrno, $fname ];
1232                                 } else {
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                                         $this->trxStatus = self::STATUS_TRX_ERROR;
1238                                         $this->trxStatusCause =
1239                                                 $this->getQueryExceptionAndLog( $lastError, $lastErrno, $sql, $fname );
1240                                         $tempIgnore = false; // cannot recover
1241                                         $this->trxStatusIgnoredCause = null;
1242                                 }
1243                         }
1244
1245                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1246                 }
1247
1248                 return $this->resultObject( $ret );
1249         }
1250
1251         /**
1252          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1253          *
1254          * @param string $sql Original SQL query
1255          * @param string $commentedSql SQL query with debugging/trace comment
1256          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1257          * @param string $fname Name of the calling function
1258          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1259          *     object for a successful read query, or false on failure
1260          */
1261         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1262                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1263                 # generalizeSQL() will probably cut down the query to reasonable
1264                 # logging size most of the time. The substr is really just a sanity check.
1265                 if ( $isMaster ) {
1266                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1267                 } else {
1268                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1269                 }
1270
1271                 # Include query transaction state
1272                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1273
1274                 $startTime = microtime( true );
1275                 if ( $this->profiler ) {
1276                         $this->profiler->profileIn( $queryProf );
1277                 }
1278                 $this->affectedRowCount = null;
1279                 $ret = $this->doQuery( $commentedSql );
1280                 $this->affectedRowCount = $this->affectedRows();
1281                 if ( $this->profiler ) {
1282                         $this->profiler->profileOut( $queryProf );
1283                 }
1284                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1285
1286                 unset( $queryProfSection ); // profile out (if set)
1287
1288                 if ( $ret !== false ) {
1289                         $this->lastPing = $startTime;
1290                         if ( $isWrite && $this->trxLevel ) {
1291                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1292                                 $this->trxWriteCallers[] = $fname;
1293                         }
1294                 }
1295
1296                 if ( $sql === self::PING_QUERY ) {
1297                         $this->rttEstimate = $queryRuntime;
1298                 }
1299
1300                 $this->trxProfiler->recordQueryCompletion(
1301                         $queryProf,
1302                         $startTime,
1303                         $isWrite,
1304                         $isWrite ? $this->affectedRows() : $this->numRows( $ret )
1305                 );
1306                 $this->queryLogger->debug( $sql, [
1307                         'method' => $fname,
1308                         'master' => $isMaster,
1309                         'runtime' => $queryRuntime,
1310                 ] );
1311
1312                 return $ret;
1313         }
1314
1315         /**
1316          * Update the estimated run-time of a query, not counting large row lock times
1317          *
1318          * LoadBalancer can be set to rollback transactions that will create huge replication
1319          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1320          * queries, like inserting a row can take a long time due to row locking. This method
1321          * uses some simple heuristics to discount those cases.
1322          *
1323          * @param string $sql A SQL write query
1324          * @param float $runtime Total runtime, including RTT
1325          * @param int $affected Affected row count
1326          */
1327         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1328                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1329                 $indicativeOfReplicaRuntime = true;
1330                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1331                         $verb = $this->getQueryVerb( $sql );
1332                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1333                         if ( $verb === 'INSERT' ) {
1334                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1335                         } elseif ( $verb === 'REPLACE' ) {
1336                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1337                         }
1338                 }
1339
1340                 $this->trxWriteDuration += $runtime;
1341                 $this->trxWriteQueryCount += 1;
1342                 $this->trxWriteAffectedRows += $affected;
1343                 if ( $indicativeOfReplicaRuntime ) {
1344                         $this->trxWriteAdjDuration += $runtime;
1345                         $this->trxWriteAdjQueryCount += 1;
1346                 }
1347         }
1348
1349         /**
1350          * Error out if the DB is not in a valid state for a query via query()
1351          *
1352          * @param string $sql
1353          * @param string $fname
1354          * @throws DBTransactionStateError
1355          */
1356         private function assertTransactionStatus( $sql, $fname ) {
1357                 $verb = $this->getQueryVerb( $sql );
1358                 if ( $verb === 'USE' ) {
1359                         throw new DBUnexpectedError( $this, "Got USE query; use selectDomain() instead." );
1360                 }
1361
1362                 if ( $verb === 'ROLLBACK' ) { // transaction/savepoint
1363                         return;
1364                 }
1365
1366                 if ( $this->trxStatus < self::STATUS_TRX_OK ) {
1367                         throw new DBTransactionStateError(
1368                                 $this,
1369                                 "Cannot execute query from $fname while transaction status is ERROR.",
1370                                 [],
1371                                 $this->trxStatusCause
1372                         );
1373                 } elseif ( $this->trxStatus === self::STATUS_TRX_OK && $this->trxStatusIgnoredCause ) {
1374                         list( $iLastError, $iLastErrno, $iFname ) = $this->trxStatusIgnoredCause;
1375                         call_user_func( $this->deprecationLogger,
1376                                 "Caller from $fname ignored an error originally raised from $iFname: " .
1377                                 "[$iLastErrno] $iLastError"
1378                         );
1379                         $this->trxStatusIgnoredCause = null;
1380                 }
1381         }
1382
1383         public function assertNoOpenTransactions() {
1384                 if ( $this->explicitTrxActive() ) {
1385                         throw new DBTransactionError(
1386                                 $this,
1387                                 "Explicit transaction still active. A caller may have caught an error. "
1388                                 . "Open transactions: " . $this->flatAtomicSectionList()
1389                         );
1390                 }
1391         }
1392
1393         /**
1394          * Determine whether or not it is safe to retry queries after a database
1395          * connection is lost
1396          *
1397          * @param string $sql SQL query
1398          * @param bool $priorWritesPending Whether there is a transaction open with
1399          *     possible write queries or transaction pre-commit/idle callbacks
1400          *     waiting on it to finish.
1401          * @return bool True if it is safe to retry the query, false otherwise
1402          */
1403         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1404                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1405                 # Dropped connections also mean that named locks are automatically released.
1406                 # Only allow error suppression in autocommit mode or when the lost transaction
1407                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1408                 if ( $this->namedLocksHeld ) {
1409                         return false; // possible critical section violation
1410                 } elseif ( $this->sessionTempTables ) {
1411                         return false; // tables might be queried latter
1412                 } elseif ( $sql === 'COMMIT' ) {
1413                         return !$priorWritesPending; // nothing written anyway? (T127428)
1414                 } elseif ( $sql === 'ROLLBACK' ) {
1415                         return true; // transaction lost...which is also what was requested :)
1416                 } elseif ( $this->explicitTrxActive() ) {
1417                         return false; // don't drop atomocity and explicit snapshots
1418                 } elseif ( $priorWritesPending ) {
1419                         return false; // prior writes lost from implicit transaction
1420                 }
1421
1422                 return true;
1423         }
1424
1425         /**
1426          * Clean things up after session (and thus transaction) loss
1427          */
1428         private function handleSessionLoss() {
1429                 // Clean up tracking of session-level things...
1430                 // https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
1431                 // https://www.postgresql.org/docs/9.2/static/sql-createtable.html (ignoring ON COMMIT)
1432                 $this->sessionTempTables = [];
1433                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1434                 // https://www.postgresql.org/docs/9.4/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1435                 $this->namedLocksHeld = [];
1436                 // Session loss implies transaction loss
1437                 $this->handleTransactionLoss();
1438         }
1439
1440         /**
1441          * Clean things up after transaction loss
1442          */
1443         private function handleTransactionLoss() {
1444                 $this->trxLevel = 0;
1445                 $this->trxAtomicCounter = 0;
1446                 $this->trxIdleCallbacks = []; // T67263; transaction already lost
1447                 $this->trxPreCommitCallbacks = []; // T67263; transaction already lost
1448                 try {
1449                         // Handle callbacks in trxEndCallbacks, e.g. onTransactionResolution().
1450                         // If callback suppression is set then the array will remain unhandled.
1451                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1452                 } catch ( Exception $ex ) {
1453                         // Already logged; move on...
1454                 }
1455                 try {
1456                         // Handle callbacks in trxRecurringCallbacks, e.g. setTransactionListener()
1457                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1458                 } catch ( Exception $ex ) {
1459                         // Already logged; move on...
1460                 }
1461         }
1462
1463         /**
1464          * Checks whether the cause of the error is detected to be a timeout.
1465          *
1466          * It returns false by default, and not all engines support detecting this yet.
1467          * If this returns false, it will be treated as a generic query error.
1468          *
1469          * @param string $error Error text
1470          * @param int $errno Error number
1471          * @return bool
1472          */
1473         protected function wasQueryTimeout( $error, $errno ) {
1474                 return false;
1475         }
1476
1477         /**
1478          * Report a query error. Log the error, and if neither the object ignore
1479          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1480          *
1481          * @param string $error
1482          * @param int $errno
1483          * @param string $sql
1484          * @param string $fname
1485          * @param bool $tempIgnore
1486          * @throws DBQueryError
1487          */
1488         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1489                 if ( $tempIgnore ) {
1490                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1491                 } else {
1492                         $exception = $this->getQueryExceptionAndLog( $error, $errno, $sql, $fname );
1493
1494                         throw $exception;
1495                 }
1496         }
1497
1498         /**
1499          * @param string $error
1500          * @param string|int $errno
1501          * @param string $sql
1502          * @param string $fname
1503          * @return DBError
1504          */
1505         private function getQueryExceptionAndLog( $error, $errno, $sql, $fname ) {
1506                 $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1507                 $this->queryLogger->error(
1508                         "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1509                         $this->getLogContext( [
1510                                 'method' => __METHOD__,
1511                                 'errno' => $errno,
1512                                 'error' => $error,
1513                                 'sql1line' => $sql1line,
1514                                 'fname' => $fname,
1515                                 'trace' => ( new RuntimeException() )->getTraceAsString()
1516                         ] )
1517                 );
1518                 $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1519                 $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1520                 if ( $wasQueryTimeout ) {
1521                         $e = new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1522                 } else {
1523                         $e = new DBQueryError( $this, $error, $errno, $sql, $fname );
1524                 }
1525
1526                 return $e;
1527         }
1528
1529         public function freeResult( $res ) {
1530         }
1531
1532         public function selectField(
1533                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1534         ) {
1535                 if ( $var === '*' ) { // sanity
1536                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1537                 }
1538
1539                 if ( !is_array( $options ) ) {
1540                         $options = [ $options ];
1541                 }
1542
1543                 $options['LIMIT'] = 1;
1544
1545                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1546                 if ( $res === false || !$this->numRows( $res ) ) {
1547                         return false;
1548                 }
1549
1550                 $row = $this->fetchRow( $res );
1551
1552                 if ( $row !== false ) {
1553                         return reset( $row );
1554                 } else {
1555                         return false;
1556                 }
1557         }
1558
1559         public function selectFieldValues(
1560                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1561         ) {
1562                 if ( $var === '*' ) { // sanity
1563                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1564                 } elseif ( !is_string( $var ) ) { // sanity
1565                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1566                 }
1567
1568                 if ( !is_array( $options ) ) {
1569                         $options = [ $options ];
1570                 }
1571
1572                 $res = $this->select( $table, [ 'value' => $var ], $cond, $fname, $options, $join_conds );
1573                 if ( $res === false ) {
1574                         return false;
1575                 }
1576
1577                 $values = [];
1578                 foreach ( $res as $row ) {
1579                         $values[] = $row->value;
1580                 }
1581
1582                 return $values;
1583         }
1584
1585         /**
1586          * Returns an optional USE INDEX clause to go after the table, and a
1587          * string to go at the end of the query.
1588          *
1589          * @param array $options Associative array of options to be turned into
1590          *   an SQL query, valid keys are listed in the function.
1591          * @return array
1592          * @see Database::select()
1593          */
1594         protected function makeSelectOptions( $options ) {
1595                 $preLimitTail = $postLimitTail = '';
1596                 $startOpts = '';
1597
1598                 $noKeyOptions = [];
1599
1600                 foreach ( $options as $key => $option ) {
1601                         if ( is_numeric( $key ) ) {
1602                                 $noKeyOptions[$option] = true;
1603                         }
1604                 }
1605
1606                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1607
1608                 $preLimitTail .= $this->makeOrderBy( $options );
1609
1610                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1611                         $postLimitTail .= ' FOR UPDATE';
1612                 }
1613
1614                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1615                         $postLimitTail .= ' LOCK IN SHARE MODE';
1616                 }
1617
1618                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1619                         $startOpts .= 'DISTINCT';
1620                 }
1621
1622                 # Various MySQL extensions
1623                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1624                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1625                 }
1626
1627                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1628                         $startOpts .= ' HIGH_PRIORITY';
1629                 }
1630
1631                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1632                         $startOpts .= ' SQL_BIG_RESULT';
1633                 }
1634
1635                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1636                         $startOpts .= ' SQL_BUFFER_RESULT';
1637                 }
1638
1639                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1640                         $startOpts .= ' SQL_SMALL_RESULT';
1641                 }
1642
1643                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1644                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1645                 }
1646
1647                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1648                         $startOpts .= ' SQL_CACHE';
1649                 }
1650
1651                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1652                         $startOpts .= ' SQL_NO_CACHE';
1653                 }
1654
1655                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1656                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1657                 } else {
1658                         $useIndex = '';
1659                 }
1660                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1661                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1662                 } else {
1663                         $ignoreIndex = '';
1664                 }
1665
1666                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1667         }
1668
1669         /**
1670          * Returns an optional GROUP BY with an optional HAVING
1671          *
1672          * @param array $options Associative array of options
1673          * @return string
1674          * @see Database::select()
1675          * @since 1.21
1676          */
1677         protected function makeGroupByWithHaving( $options ) {
1678                 $sql = '';
1679                 if ( isset( $options['GROUP BY'] ) ) {
1680                         $gb = is_array( $options['GROUP BY'] )
1681                                 ? implode( ',', $options['GROUP BY'] )
1682                                 : $options['GROUP BY'];
1683                         $sql .= ' GROUP BY ' . $gb;
1684                 }
1685                 if ( isset( $options['HAVING'] ) ) {
1686                         $having = is_array( $options['HAVING'] )
1687                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1688                                 : $options['HAVING'];
1689                         $sql .= ' HAVING ' . $having;
1690                 }
1691
1692                 return $sql;
1693         }
1694
1695         /**
1696          * Returns an optional ORDER BY
1697          *
1698          * @param array $options Associative array of options
1699          * @return string
1700          * @see Database::select()
1701          * @since 1.21
1702          */
1703         protected function makeOrderBy( $options ) {
1704                 if ( isset( $options['ORDER BY'] ) ) {
1705                         $ob = is_array( $options['ORDER BY'] )
1706                                 ? implode( ',', $options['ORDER BY'] )
1707                                 : $options['ORDER BY'];
1708
1709                         return ' ORDER BY ' . $ob;
1710                 }
1711
1712                 return '';
1713         }
1714
1715         public function select(
1716                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1717         ) {
1718                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1719
1720                 return $this->query( $sql, $fname );
1721         }
1722
1723         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1724                 $options = [], $join_conds = []
1725         ) {
1726                 if ( is_array( $vars ) ) {
1727                         $fields = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1728                 } else {
1729                         $fields = $vars;
1730                 }
1731
1732                 $options = (array)$options;
1733                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1734                         ? $options['USE INDEX']
1735                         : [];
1736                 $ignoreIndexes = (
1737                         isset( $options['IGNORE INDEX'] ) &&
1738                         is_array( $options['IGNORE INDEX'] )
1739                 )
1740                         ? $options['IGNORE INDEX']
1741                         : [];
1742
1743                 if (
1744                         $this->selectOptionsIncludeLocking( $options ) &&
1745                         $this->selectFieldsOrOptionsAggregate( $vars, $options )
1746                 ) {
1747                         // Some DB types (postgres/oracle) disallow FOR UPDATE with aggregate
1748                         // functions. Discourage use of such queries to encourage compatibility.
1749                         call_user_func(
1750                                 $this->deprecationLogger,
1751                                 __METHOD__ . ": aggregation used with a locking SELECT ($fname)."
1752                         );
1753                 }
1754
1755                 if ( is_array( $table ) ) {
1756                         $from = ' FROM ' .
1757                                 $this->tableNamesWithIndexClauseOrJOIN(
1758                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1759                 } elseif ( $table != '' ) {
1760                         $from = ' FROM ' .
1761                                 $this->tableNamesWithIndexClauseOrJOIN(
1762                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1763                 } else {
1764                         $from = '';
1765                 }
1766
1767                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1768                         $this->makeSelectOptions( $options );
1769
1770                 if ( is_array( $conds ) ) {
1771                         $conds = $this->makeList( $conds, self::LIST_AND );
1772                 }
1773
1774                 if ( $conds === null || $conds === false ) {
1775                         $this->queryLogger->warning(
1776                                 __METHOD__
1777                                 . ' called from '
1778                                 . $fname
1779                                 . ' with incorrect parameters: $conds must be a string or an array'
1780                         );
1781                         $conds = '';
1782                 }
1783
1784                 if ( $conds === '' || $conds === '*' ) {
1785                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex $preLimitTail";
1786                 } elseif ( is_string( $conds ) ) {
1787                         $sql = "SELECT $startOpts $fields $from $useIndex $ignoreIndex " .
1788                                 "WHERE $conds $preLimitTail";
1789                 } else {
1790                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1791                 }
1792
1793                 if ( isset( $options['LIMIT'] ) ) {
1794                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1795                                 $options['OFFSET'] ?? false );
1796                 }
1797                 $sql = "$sql $postLimitTail";
1798
1799                 if ( isset( $options['EXPLAIN'] ) ) {
1800                         $sql = 'EXPLAIN ' . $sql;
1801                 }
1802
1803                 return $sql;
1804         }
1805
1806         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1807                 $options = [], $join_conds = []
1808         ) {
1809                 $options = (array)$options;
1810                 $options['LIMIT'] = 1;
1811                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1812
1813                 if ( $res === false ) {
1814                         return false;
1815                 }
1816
1817                 if ( !$this->numRows( $res ) ) {
1818                         return false;
1819                 }
1820
1821                 $obj = $this->fetchObject( $res );
1822
1823                 return $obj;
1824         }
1825
1826         public function estimateRowCount(
1827                 $table, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1828         ) {
1829                 $conds = $this->normalizeConditions( $conds, $fname );
1830                 $column = $this->extractSingleFieldFromList( $var );
1831                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1832                         $conds[] = "$column IS NOT NULL";
1833                 }
1834
1835                 $res = $this->select(
1836                         $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options, $join_conds
1837                 );
1838                 $row = $res ? $this->fetchRow( $res ) : [];
1839
1840                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1841         }
1842
1843         public function selectRowCount(
1844                 $tables, $var = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1845         ) {
1846                 $conds = $this->normalizeConditions( $conds, $fname );
1847                 $column = $this->extractSingleFieldFromList( $var );
1848                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
1849                         $conds[] = "$column IS NOT NULL";
1850                 }
1851
1852                 $res = $this->select(
1853                         [
1854                                 'tmp_count' => $this->buildSelectSubquery(
1855                                         $tables,
1856                                         '1',
1857                                         $conds,
1858                                         $fname,
1859                                         $options,
1860                                         $join_conds
1861                                 )
1862                         ],
1863                         [ 'rowcount' => 'COUNT(*)' ],
1864                         [],
1865                         $fname
1866                 );
1867                 $row = $res ? $this->fetchRow( $res ) : [];
1868
1869                 return isset( $row['rowcount'] ) ? (int)$row['rowcount'] : 0;
1870         }
1871
1872         /**
1873          * @param string|array $options
1874          * @return bool
1875          */
1876         private function selectOptionsIncludeLocking( $options ) {
1877                 $options = (array)$options;
1878                 foreach ( [ 'FOR UPDATE', 'LOCK IN SHARE MODE' ] as $lock ) {
1879                         if ( in_array( $lock, $options, true ) ) {
1880                                 return true;
1881                         }
1882                 }
1883
1884                 return false;
1885         }
1886
1887         /**
1888          * @param array|string $fields
1889          * @param array|string $options
1890          * @return bool
1891          */
1892         private function selectFieldsOrOptionsAggregate( $fields, $options ) {
1893                 foreach ( (array)$options as $key => $value ) {
1894                         if ( is_string( $key ) ) {
1895                                 if ( preg_match( '/^(?:GROUP BY|HAVING)$/i', $key ) ) {
1896                                         return true;
1897                                 }
1898                         } elseif ( is_string( $value ) ) {
1899                                 if ( preg_match( '/^(?:DISTINCT|DISTINCTROW)$/i', $value ) ) {
1900                                         return true;
1901                                 }
1902                         }
1903                 }
1904
1905                 $regex = '/^(?:COUNT|MIN|MAX|SUM|GROUP_CONCAT|LISTAGG|ARRAY_AGG)\s*\\(/i';
1906                 foreach ( (array)$fields as $field ) {
1907                         if ( is_string( $field ) && preg_match( $regex, $field ) ) {
1908                                 return true;
1909                         }
1910                 }
1911
1912                 return false;
1913         }
1914
1915         /**
1916          * @param array|string $conds
1917          * @param string $fname
1918          * @return array
1919          */
1920         final protected function normalizeConditions( $conds, $fname ) {
1921                 if ( $conds === null || $conds === false ) {
1922                         $this->queryLogger->warning(
1923                                 __METHOD__
1924                                 . ' called from '
1925                                 . $fname
1926                                 . ' with incorrect parameters: $conds must be a string or an array'
1927                         );
1928                         $conds = '';
1929                 }
1930
1931                 if ( !is_array( $conds ) ) {
1932                         $conds = ( $conds === '' ) ? [] : [ $conds ];
1933                 }
1934
1935                 return $conds;
1936         }
1937
1938         /**
1939          * @param array|string $var Field parameter in the style of select()
1940          * @return string|null Column name or null; ignores aliases
1941          * @throws DBUnexpectedError Errors out if multiple columns are given
1942          */
1943         final protected function extractSingleFieldFromList( $var ) {
1944                 if ( is_array( $var ) ) {
1945                         if ( !$var ) {
1946                                 $column = null;
1947                         } elseif ( count( $var ) == 1 ) {
1948                                 $column = $var[0] ?? reset( $var );
1949                         } else {
1950                                 throw new DBUnexpectedError( $this, __METHOD__ . ': got multiple columns.' );
1951                         }
1952                 } else {
1953                         $column = $var;
1954                 }
1955
1956                 return $column;
1957         }
1958
1959         public function lockForUpdate(
1960                 $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1961         ) {
1962                 if ( !$this->trxLevel && !$this->getFlag( self::DBO_TRX ) ) {
1963                         throw new DBUnexpectedError(
1964                                 $this,
1965                                 __METHOD__ . ': no transaction is active nor is DBO_TRX set'
1966                         );
1967                 }
1968
1969                 $options = (array)$options;
1970                 $options[] = 'FOR UPDATE';
1971
1972                 return $this->selectRowCount( $table, '*', $conds, $fname, $options, $join_conds );
1973         }
1974
1975         /**
1976          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1977          * It's only slightly flawed. Don't use for anything important.
1978          *
1979          * @param string $sql A SQL Query
1980          *
1981          * @return string
1982          */
1983         protected static function generalizeSQL( $sql ) {
1984                 # This does the same as the regexp below would do, but in such a way
1985                 # as to avoid crashing php on some large strings.
1986                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1987
1988                 $sql = str_replace( "\\\\", '', $sql );
1989                 $sql = str_replace( "\\'", '', $sql );
1990                 $sql = str_replace( "\\\"", '', $sql );
1991                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1992                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1993
1994                 # All newlines, tabs, etc replaced by single space
1995                 $sql = preg_replace( '/\s+/', ' ', $sql );
1996
1997                 # All numbers => N,
1998                 # except the ones surrounded by characters, e.g. l10n
1999                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
2000                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
2001
2002                 return $sql;
2003         }
2004
2005         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
2006                 $info = $this->fieldInfo( $table, $field );
2007
2008                 return (bool)$info;
2009         }
2010
2011         public function indexExists( $table, $index, $fname = __METHOD__ ) {
2012                 if ( !$this->tableExists( $table ) ) {
2013                         return null;
2014                 }
2015
2016                 $info = $this->indexInfo( $table, $index, $fname );
2017                 if ( is_null( $info ) ) {
2018                         return null;
2019                 } else {
2020                         return $info !== false;
2021                 }
2022         }
2023
2024         abstract public function tableExists( $table, $fname = __METHOD__ );
2025
2026         public function indexUnique( $table, $index ) {
2027                 $indexInfo = $this->indexInfo( $table, $index );
2028
2029                 if ( !$indexInfo ) {
2030                         return null;
2031                 }
2032
2033                 return !$indexInfo[0]->Non_unique;
2034         }
2035
2036         /**
2037          * Helper for Database::insert().
2038          *
2039          * @param array $options
2040          * @return string
2041          */
2042         protected function makeInsertOptions( $options ) {
2043                 return implode( ' ', $options );
2044         }
2045
2046         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
2047                 # No rows to insert, easy just return now
2048                 if ( !count( $a ) ) {
2049                         return true;
2050                 }
2051
2052                 $table = $this->tableName( $table );
2053
2054                 if ( !is_array( $options ) ) {
2055                         $options = [ $options ];
2056                 }
2057
2058                 $options = $this->makeInsertOptions( $options );
2059
2060                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2061                         $multi = true;
2062                         $keys = array_keys( $a[0] );
2063                 } else {
2064                         $multi = false;
2065                         $keys = array_keys( $a );
2066                 }
2067
2068                 $sql = 'INSERT ' . $options .
2069                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2070
2071                 if ( $multi ) {
2072                         $first = true;
2073                         foreach ( $a as $row ) {
2074                                 if ( $first ) {
2075                                         $first = false;
2076                                 } else {
2077                                         $sql .= ',';
2078                                 }
2079                                 $sql .= '(' . $this->makeList( $row ) . ')';
2080                         }
2081                 } else {
2082                         $sql .= '(' . $this->makeList( $a ) . ')';
2083                 }
2084
2085                 $this->query( $sql, $fname );
2086
2087                 return true;
2088         }
2089
2090         /**
2091          * Make UPDATE options array for Database::makeUpdateOptions
2092          *
2093          * @param array $options
2094          * @return array
2095          */
2096         protected function makeUpdateOptionsArray( $options ) {
2097                 if ( !is_array( $options ) ) {
2098                         $options = [ $options ];
2099                 }
2100
2101                 $opts = [];
2102
2103                 if ( in_array( 'IGNORE', $options ) ) {
2104                         $opts[] = 'IGNORE';
2105                 }
2106
2107                 return $opts;
2108         }
2109
2110         /**
2111          * Make UPDATE options for the Database::update function
2112          *
2113          * @param array $options The options passed to Database::update
2114          * @return string
2115          */
2116         protected function makeUpdateOptions( $options ) {
2117                 $opts = $this->makeUpdateOptionsArray( $options );
2118
2119                 return implode( ' ', $opts );
2120         }
2121
2122         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
2123                 $table = $this->tableName( $table );
2124                 $opts = $this->makeUpdateOptions( $options );
2125                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
2126
2127                 if ( $conds !== [] && $conds !== '*' ) {
2128                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
2129                 }
2130
2131                 $this->query( $sql, $fname );
2132
2133                 return true;
2134         }
2135
2136         public function makeList( $a, $mode = self::LIST_COMMA ) {
2137                 if ( !is_array( $a ) ) {
2138                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
2139                 }
2140
2141                 $first = true;
2142                 $list = '';
2143
2144                 foreach ( $a as $field => $value ) {
2145                         if ( !$first ) {
2146                                 if ( $mode == self::LIST_AND ) {
2147                                         $list .= ' AND ';
2148                                 } elseif ( $mode == self::LIST_OR ) {
2149                                         $list .= ' OR ';
2150                                 } else {
2151                                         $list .= ',';
2152                                 }
2153                         } else {
2154                                 $first = false;
2155                         }
2156
2157                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
2158                                 $list .= "($value)";
2159                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
2160                                 $list .= "$value";
2161                         } elseif (
2162                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
2163                         ) {
2164                                 // Remove null from array to be handled separately if found
2165                                 $includeNull = false;
2166                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2167                                         $includeNull = true;
2168                                         unset( $value[$nullKey] );
2169                                 }
2170                                 if ( count( $value ) == 0 && !$includeNull ) {
2171                                         throw new InvalidArgumentException(
2172                                                 __METHOD__ . ": empty input for field $field" );
2173                                 } elseif ( count( $value ) == 0 ) {
2174                                         // only check if $field is null
2175                                         $list .= "$field IS NULL";
2176                                 } else {
2177                                         // IN clause contains at least one valid element
2178                                         if ( $includeNull ) {
2179                                                 // Group subconditions to ensure correct precedence
2180                                                 $list .= '(';
2181                                         }
2182                                         if ( count( $value ) == 1 ) {
2183                                                 // Special-case single values, as IN isn't terribly efficient
2184                                                 // Don't necessarily assume the single key is 0; we don't
2185                                                 // enforce linear numeric ordering on other arrays here.
2186                                                 $value = array_values( $value )[0];
2187                                                 $list .= $field . " = " . $this->addQuotes( $value );
2188                                         } else {
2189                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2190                                         }
2191                                         // if null present in array, append IS NULL
2192                                         if ( $includeNull ) {
2193                                                 $list .= " OR $field IS NULL)";
2194                                         }
2195                                 }
2196                         } elseif ( $value === null ) {
2197                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
2198                                         $list .= "$field IS ";
2199                                 } elseif ( $mode == self::LIST_SET ) {
2200                                         $list .= "$field = ";
2201                                 }
2202                                 $list .= 'NULL';
2203                         } else {
2204                                 if (
2205                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
2206                                 ) {
2207                                         $list .= "$field = ";
2208                                 }
2209                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
2210                         }
2211                 }
2212
2213                 return $list;
2214         }
2215
2216         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2217                 $conds = [];
2218
2219                 foreach ( $data as $base => $sub ) {
2220                         if ( count( $sub ) ) {
2221                                 $conds[] = $this->makeList(
2222                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
2223                                         self::LIST_AND );
2224                         }
2225                 }
2226
2227                 if ( $conds ) {
2228                         return $this->makeList( $conds, self::LIST_OR );
2229                 } else {
2230                         // Nothing to search for...
2231                         return false;
2232                 }
2233         }
2234
2235         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2236                 return $valuename;
2237         }
2238
2239         public function bitNot( $field ) {
2240                 return "(~$field)";
2241         }
2242
2243         public function bitAnd( $fieldLeft, $fieldRight ) {
2244                 return "($fieldLeft & $fieldRight)";
2245         }
2246
2247         public function bitOr( $fieldLeft, $fieldRight ) {
2248                 return "($fieldLeft | $fieldRight)";
2249         }
2250
2251         public function buildConcat( $stringList ) {
2252                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2253         }
2254
2255         public function buildGroupConcatField(
2256                 $delim, $table, $field, $conds = '', $join_conds = []
2257         ) {
2258                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2259
2260                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
2261         }
2262
2263         public function buildSubstring( $input, $startPosition, $length = null ) {
2264                 $this->assertBuildSubstringParams( $startPosition, $length );
2265                 $functionBody = "$input FROM $startPosition";
2266                 if ( $length !== null ) {
2267                         $functionBody .= " FOR $length";
2268                 }
2269                 return 'SUBSTRING(' . $functionBody . ')';
2270         }
2271
2272         /**
2273          * Check type and bounds for parameters to self::buildSubstring()
2274          *
2275          * All supported databases have substring functions that behave the same for
2276          * positive $startPosition and non-negative $length, but behaviors differ when
2277          * given 0 or negative $startPosition or negative $length. The simplest
2278          * solution to that is to just forbid those values.
2279          *
2280          * @param int $startPosition
2281          * @param int|null $length
2282          * @since 1.31
2283          */
2284         protected function assertBuildSubstringParams( $startPosition, $length ) {
2285                 if ( !is_int( $startPosition ) || $startPosition <= 0 ) {
2286                         throw new InvalidArgumentException(
2287                                 '$startPosition must be a positive integer'
2288                         );
2289                 }
2290                 if ( !( is_int( $length ) && $length >= 0 || $length === null ) ) {
2291                         throw new InvalidArgumentException(
2292                                 '$length must be null or an integer greater than or equal to 0'
2293                         );
2294                 }
2295         }
2296
2297         public function buildStringCast( $field ) {
2298                 // In theory this should work for any standards-compliant
2299                 // SQL implementation, although it may not be the best way to do it.
2300                 return "CAST( $field AS CHARACTER )";
2301         }
2302
2303         public function buildIntegerCast( $field ) {
2304                 return 'CAST( ' . $field . ' AS INTEGER )';
2305         }
2306
2307         public function buildSelectSubquery(
2308                 $table, $vars, $conds = '', $fname = __METHOD__,
2309                 $options = [], $join_conds = []
2310         ) {
2311                 return new Subquery(
2312                         $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds )
2313                 );
2314         }
2315
2316         public function databasesAreIndependent() {
2317                 return false;
2318         }
2319
2320         final public function selectDB( $db ) {
2321                 $this->selectDomain( new DatabaseDomain(
2322                         $db,
2323                         $this->currentDomain->getSchema(),
2324                         $this->currentDomain->getTablePrefix()
2325                 ) );
2326
2327                 return true;
2328         }
2329
2330         final public function selectDomain( $domain ) {
2331                 $this->doSelectDomain( DatabaseDomain::newFromId( $domain ) );
2332         }
2333
2334         protected function doSelectDomain( DatabaseDomain $domain ) {
2335                 $this->currentDomain = $domain;
2336         }
2337
2338         public function getDBname() {
2339                 return $this->currentDomain->getDatabase();
2340         }
2341
2342         public function getServer() {
2343                 return $this->server;
2344         }
2345
2346         public function tableName( $name, $format = 'quoted' ) {
2347                 if ( $name instanceof Subquery ) {
2348                         throw new DBUnexpectedError(
2349                                 $this,
2350                                 __METHOD__ . ': got Subquery instance when expecting a string.'
2351                         );
2352                 }
2353
2354                 # Skip the entire process when we have a string quoted on both ends.
2355                 # Note that we check the end so that we will still quote any use of
2356                 # use of `database`.table. But won't break things if someone wants
2357                 # to query a database table with a dot in the name.
2358                 if ( $this->isQuotedIdentifier( $name ) ) {
2359                         return $name;
2360                 }
2361
2362                 # Lets test for any bits of text that should never show up in a table
2363                 # name. Basically anything like JOIN or ON which are actually part of
2364                 # SQL queries, but may end up inside of the table value to combine
2365                 # sql. Such as how the API is doing.
2366                 # Note that we use a whitespace test rather than a \b test to avoid
2367                 # any remote case where a word like on may be inside of a table name
2368                 # surrounded by symbols which may be considered word breaks.
2369                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2370                         $this->queryLogger->warning(
2371                                 __METHOD__ . ": use of subqueries is not supported this way.",
2372                                 [ 'trace' => ( new RuntimeException() )->getTraceAsString() ]
2373                         );
2374
2375                         return $name;
2376                 }
2377
2378                 # Split database and table into proper variables.
2379                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
2380
2381                 # Quote $table and apply the prefix if not quoted.
2382                 # $tableName might be empty if this is called from Database::replaceVars()
2383                 $tableName = "{$prefix}{$table}";
2384                 if ( $format === 'quoted'
2385                         && !$this->isQuotedIdentifier( $tableName )
2386                         && $tableName !== ''
2387                 ) {
2388                         $tableName = $this->addIdentifierQuotes( $tableName );
2389                 }
2390
2391                 # Quote $schema and $database and merge them with the table name if needed
2392                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
2393                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
2394
2395                 return $tableName;
2396         }
2397
2398         /**
2399          * Get the table components needed for a query given the currently selected database
2400          *
2401          * @param string $name Table name in the form of db.schema.table, db.table, or table
2402          * @return array (DB name or "" for default, schema name, table prefix, table name)
2403          */
2404         protected function qualifiedTableComponents( $name ) {
2405                 # We reverse the explode so that database.table and table both output the correct table.
2406                 $dbDetails = explode( '.', $name, 3 );
2407                 if ( count( $dbDetails ) == 3 ) {
2408                         list( $database, $schema, $table ) = $dbDetails;
2409                         # We don't want any prefix added in this case
2410                         $prefix = '';
2411                 } elseif ( count( $dbDetails ) == 2 ) {
2412                         list( $database, $table ) = $dbDetails;
2413                         # We don't want any prefix added in this case
2414                         $prefix = '';
2415                         # In dbs that support it, $database may actually be the schema
2416                         # but that doesn't affect any of the functionality here
2417                         $schema = '';
2418                 } else {
2419                         list( $table ) = $dbDetails;
2420                         if ( isset( $this->tableAliases[$table] ) ) {
2421                                 $database = $this->tableAliases[$table]['dbname'];
2422                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
2423                                         ? $this->tableAliases[$table]['schema']
2424                                         : $this->relationSchemaQualifier();
2425                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
2426                                         ? $this->tableAliases[$table]['prefix']
2427                                         : $this->tablePrefix();
2428                         } else {
2429                                 $database = '';
2430                                 $schema = $this->relationSchemaQualifier(); # Default schema
2431                                 $prefix = $this->tablePrefix(); # Default prefix
2432                         }
2433                 }
2434
2435                 return [ $database, $schema, $prefix, $table ];
2436         }
2437
2438         /**
2439          * @param string|null $namespace Database or schema
2440          * @param string $relation Name of table, view, sequence, etc...
2441          * @param string $format One of (raw, quoted)
2442          * @return string Relation name with quoted and merged $namespace as needed
2443          */
2444         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
2445                 if ( strlen( $namespace ) ) {
2446                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
2447                                 $namespace = $this->addIdentifierQuotes( $namespace );
2448                         }
2449                         $relation = $namespace . '.' . $relation;
2450                 }
2451
2452                 return $relation;
2453         }
2454
2455         public function tableNames() {
2456                 $inArray = func_get_args();
2457                 $retVal = [];
2458
2459                 foreach ( $inArray as $name ) {
2460                         $retVal[$name] = $this->tableName( $name );
2461                 }
2462
2463                 return $retVal;
2464         }
2465
2466         public function tableNamesN() {
2467                 $inArray = func_get_args();
2468                 $retVal = [];
2469
2470                 foreach ( $inArray as $name ) {
2471                         $retVal[] = $this->tableName( $name );
2472                 }
2473
2474                 return $retVal;
2475         }
2476
2477         /**
2478          * Get an aliased table name
2479          *
2480          * This returns strings like "tableName AS newTableName" for aliased tables
2481          * and "(SELECT * from tableA) newTablename" for subqueries (e.g. derived tables)
2482          *
2483          * @see Database::tableName()
2484          * @param string|Subquery $table Table name or object with a 'sql' field
2485          * @param string|bool $alias Table alias (optional)
2486          * @return string SQL name for aliased table. Will not alias a table to its own name
2487          */
2488         protected function tableNameWithAlias( $table, $alias = false ) {
2489                 if ( is_string( $table ) ) {
2490                         $quotedTable = $this->tableName( $table );
2491                 } elseif ( $table instanceof Subquery ) {
2492                         $quotedTable = (string)$table;
2493                 } else {
2494                         throw new InvalidArgumentException( "Table must be a string or Subquery." );
2495                 }
2496
2497                 if ( !strlen( $alias ) || $alias === $table ) {
2498                         if ( $table instanceof Subquery ) {
2499                                 throw new InvalidArgumentException( "Subquery table missing alias." );
2500                         }
2501
2502                         return $quotedTable;
2503                 } else {
2504                         return $quotedTable . ' ' . $this->addIdentifierQuotes( $alias );
2505                 }
2506         }
2507
2508         /**
2509          * Gets an array of aliased table names
2510          *
2511          * @param array $tables [ [alias] => table ]
2512          * @return string[] See tableNameWithAlias()
2513          */
2514         protected function tableNamesWithAlias( $tables ) {
2515                 $retval = [];
2516                 foreach ( $tables as $alias => $table ) {
2517                         if ( is_numeric( $alias ) ) {
2518                                 $alias = $table;
2519                         }
2520                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2521                 }
2522
2523                 return $retval;
2524         }
2525
2526         /**
2527          * Get an aliased field name
2528          * e.g. fieldName AS newFieldName
2529          *
2530          * @param string $name Field name
2531          * @param string|bool $alias Alias (optional)
2532          * @return string SQL name for aliased field. Will not alias a field to its own name
2533          */
2534         protected function fieldNameWithAlias( $name, $alias = false ) {
2535                 if ( !$alias || (string)$alias === (string)$name ) {
2536                         return $name;
2537                 } else {
2538                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2539                 }
2540         }
2541
2542         /**
2543          * Gets an array of aliased field names
2544          *
2545          * @param array $fields [ [alias] => field ]
2546          * @return string[] See fieldNameWithAlias()
2547          */
2548         protected function fieldNamesWithAlias( $fields ) {
2549                 $retval = [];
2550                 foreach ( $fields as $alias => $field ) {
2551                         if ( is_numeric( $alias ) ) {
2552                                 $alias = $field;
2553                         }
2554                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2555                 }
2556
2557                 return $retval;
2558         }
2559
2560         /**
2561          * Get the aliased table name clause for a FROM clause
2562          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2563          *
2564          * @param array $tables ( [alias] => table )
2565          * @param array $use_index Same as for select()
2566          * @param array $ignore_index Same as for select()
2567          * @param array $join_conds Same as for select()
2568          * @return string
2569          */
2570         protected function tableNamesWithIndexClauseOrJOIN(
2571                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2572         ) {
2573                 $ret = [];
2574                 $retJOIN = [];
2575                 $use_index = (array)$use_index;
2576                 $ignore_index = (array)$ignore_index;
2577                 $join_conds = (array)$join_conds;
2578
2579                 foreach ( $tables as $alias => $table ) {
2580                         if ( !is_string( $alias ) ) {
2581                                 // No alias? Set it equal to the table name
2582                                 $alias = $table;
2583                         }
2584
2585                         if ( is_array( $table ) ) {
2586                                 // A parenthesized group
2587                                 if ( count( $table ) > 1 ) {
2588                                         $joinedTable = '(' .
2589                                                 $this->tableNamesWithIndexClauseOrJOIN(
2590                                                         $table, $use_index, $ignore_index, $join_conds ) . ')';
2591                                 } else {
2592                                         // Degenerate case
2593                                         $innerTable = reset( $table );
2594                                         $innerAlias = key( $table );
2595                                         $joinedTable = $this->tableNameWithAlias(
2596                                                 $innerTable,
2597                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2598                                         );
2599                                 }
2600                         } else {
2601                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2602                         }
2603
2604                         // Is there a JOIN clause for this table?
2605                         if ( isset( $join_conds[$alias] ) ) {
2606                                 list( $joinType, $conds ) = $join_conds[$alias];
2607                                 $tableClause = $joinType;
2608                                 $tableClause .= ' ' . $joinedTable;
2609                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2610                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2611                                         if ( $use != '' ) {
2612                                                 $tableClause .= ' ' . $use;
2613                                         }
2614                                 }
2615                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2616                                         $ignore = $this->ignoreIndexClause(
2617                                                 implode( ',', (array)$ignore_index[$alias] ) );
2618                                         if ( $ignore != '' ) {
2619                                                 $tableClause .= ' ' . $ignore;
2620                                         }
2621                                 }
2622                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2623                                 if ( $on != '' ) {
2624                                         $tableClause .= ' ON (' . $on . ')';
2625                                 }
2626
2627                                 $retJOIN[] = $tableClause;
2628                         } elseif ( isset( $use_index[$alias] ) ) {
2629                                 // Is there an INDEX clause for this table?
2630                                 $tableClause = $joinedTable;
2631                                 $tableClause .= ' ' . $this->useIndexClause(
2632                                                 implode( ',', (array)$use_index[$alias] )
2633                                         );
2634
2635                                 $ret[] = $tableClause;
2636                         } elseif ( isset( $ignore_index[$alias] ) ) {
2637                                 // Is there an INDEX clause for this table?
2638                                 $tableClause = $joinedTable;
2639                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2640                                                 implode( ',', (array)$ignore_index[$alias] )
2641                                         );
2642
2643                                 $ret[] = $tableClause;
2644                         } else {
2645                                 $tableClause = $joinedTable;
2646
2647                                 $ret[] = $tableClause;
2648                         }
2649                 }
2650
2651                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2652                 $implicitJoins = $ret ? implode( ',', $ret ) : "";
2653                 $explicitJoins = $retJOIN ? implode( ' ', $retJOIN ) : "";
2654
2655                 // Compile our final table clause
2656                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2657         }
2658
2659         /**
2660          * Allows for index remapping in queries where this is not consistent across DBMS
2661          *
2662          * @param string $index
2663          * @return string
2664          */
2665         protected function indexName( $index ) {
2666                 return $this->indexAliases[$index] ?? $index;
2667         }
2668
2669         public function addQuotes( $s ) {
2670                 if ( $s instanceof Blob ) {
2671                         $s = $s->fetch();
2672                 }
2673                 if ( $s === null ) {
2674                         return 'NULL';
2675                 } elseif ( is_bool( $s ) ) {
2676                         return (int)$s;
2677                 } else {
2678                         # This will also quote numeric values. This should be harmless,
2679                         # and protects against weird problems that occur when they really
2680                         # _are_ strings such as article titles and string->number->string
2681                         # conversion is not 1:1.
2682                         return "'" . $this->strencode( $s ) . "'";
2683                 }
2684         }
2685
2686         public function addIdentifierQuotes( $s ) {
2687                 return '"' . str_replace( '"', '""', $s ) . '"';
2688         }
2689
2690         /**
2691          * Returns if the given identifier looks quoted or not according to
2692          * the database convention for quoting identifiers .
2693          *
2694          * @note Do not use this to determine if untrusted input is safe.
2695          *   A malicious user can trick this function.
2696          * @param string $name
2697          * @return bool
2698          */
2699         public function isQuotedIdentifier( $name ) {
2700                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2701         }
2702
2703         /**
2704          * @param string $s
2705          * @param string $escapeChar
2706          * @return string
2707          */
2708         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2709                 return str_replace( [ $escapeChar, '%', '_' ],
2710                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2711                         $s );
2712         }
2713
2714         public function buildLike() {
2715                 $params = func_get_args();
2716
2717                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2718                         $params = $params[0];
2719                 }
2720
2721                 $s = '';
2722
2723                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2724                 // may escape backslashes, creating problems of double escaping. The `
2725                 // character has good cross-DBMS compatibility, avoiding special operators
2726                 // in MS SQL like ^ and %
2727                 $escapeChar = '`';
2728
2729                 foreach ( $params as $value ) {
2730                         if ( $value instanceof LikeMatch ) {
2731                                 $s .= $value->toString();
2732                         } else {
2733                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2734                         }
2735                 }
2736
2737                 return ' LIKE ' .
2738                         $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2739         }
2740
2741         public function anyChar() {
2742                 return new LikeMatch( '_' );
2743         }
2744
2745         public function anyString() {
2746                 return new LikeMatch( '%' );
2747         }
2748
2749         public function nextSequenceValue( $seqName ) {
2750                 return null;
2751         }
2752
2753         /**
2754          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2755          * is only needed because a) MySQL must be as efficient as possible due to
2756          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2757          * which index to pick. Anyway, other databases might have different
2758          * indexes on a given table. So don't bother overriding this unless you're
2759          * MySQL.
2760          * @param string $index
2761          * @return string
2762          */
2763         public function useIndexClause( $index ) {
2764                 return '';
2765         }
2766
2767         /**
2768          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2769          * is only needed because a) MySQL must be as efficient as possible due to
2770          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2771          * which index to pick. Anyway, other databases might have different
2772          * indexes on a given table. So don't bother overriding this unless you're
2773          * MySQL.
2774          * @param string $index
2775          * @return string
2776          */
2777         public function ignoreIndexClause( $index ) {
2778                 return '';
2779         }
2780
2781         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2782                 if ( count( $rows ) == 0 ) {
2783                         return;
2784                 }
2785
2786                 $uniqueIndexes = (array)$uniqueIndexes;
2787                 // Single row case
2788                 if ( !is_array( reset( $rows ) ) ) {
2789                         $rows = [ $rows ];
2790                 }
2791
2792                 try {
2793                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2794                         $affectedRowCount = 0;
2795                         foreach ( $rows as $row ) {
2796                                 // Delete rows which collide with this one
2797                                 $indexWhereClauses = [];
2798                                 foreach ( $uniqueIndexes as $index ) {
2799                                         $indexColumns = (array)$index;
2800                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2801                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2802                                                 throw new DBUnexpectedError(
2803                                                         $this,
2804                                                         'New record does not provide all values for unique key (' .
2805                                                         implode( ', ', $indexColumns ) . ')'
2806                                                 );
2807                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2808                                                 throw new DBUnexpectedError(
2809                                                         $this,
2810                                                         'New record has a null value for unique key (' .
2811                                                         implode( ', ', $indexColumns ) . ')'
2812                                                 );
2813                                         }
2814                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2815                                 }
2816
2817                                 if ( $indexWhereClauses ) {
2818                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2819                                         $affectedRowCount += $this->affectedRows();
2820                                 }
2821
2822                                 // Now insert the row
2823                                 $this->insert( $table, $row, $fname );
2824                                 $affectedRowCount += $this->affectedRows();
2825                         }
2826                         $this->endAtomic( $fname );
2827                         $this->affectedRowCount = $affectedRowCount;
2828                 } catch ( Exception $e ) {
2829                         $this->cancelAtomic( $fname );
2830                         throw $e;
2831                 }
2832         }
2833
2834         /**
2835          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2836          * statement.
2837          *
2838          * @param string $table Table name
2839          * @param array|string $rows Row(s) to insert
2840          * @param string $fname Caller function name
2841          */
2842         protected function nativeReplace( $table, $rows, $fname ) {
2843                 $table = $this->tableName( $table );
2844
2845                 # Single row case
2846                 if ( !is_array( reset( $rows ) ) ) {
2847                         $rows = [ $rows ];
2848                 }
2849
2850                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2851                 $first = true;
2852
2853                 foreach ( $rows as $row ) {
2854                         if ( $first ) {
2855                                 $first = false;
2856                         } else {
2857                                 $sql .= ',';
2858                         }
2859
2860                         $sql .= '(' . $this->makeList( $row ) . ')';
2861                 }
2862
2863                 $this->query( $sql, $fname );
2864         }
2865
2866         public function upsert( $table, array $rows, $uniqueIndexes, array $set,
2867                 $fname = __METHOD__
2868         ) {
2869                 if ( $rows === [] ) {
2870                         return true; // nothing to do
2871                 }
2872
2873                 $uniqueIndexes = (array)$uniqueIndexes;
2874                 if ( !is_array( reset( $rows ) ) ) {
2875                         $rows = [ $rows ];
2876                 }
2877
2878                 if ( count( $uniqueIndexes ) ) {
2879                         $clauses = []; // list WHERE clauses that each identify a single row
2880                         foreach ( $rows as $row ) {
2881                                 foreach ( $uniqueIndexes as $index ) {
2882                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2883                                         $rowKey = []; // unique key to this row
2884                                         foreach ( $index as $column ) {
2885                                                 $rowKey[$column] = $row[$column];
2886                                         }
2887                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2888                                 }
2889                         }
2890                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2891                 } else {
2892                         $where = false;
2893                 }
2894
2895                 $affectedRowCount = 0;
2896                 try {
2897                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
2898                         # Update any existing conflicting row(s)
2899                         if ( $where !== false ) {
2900                                 $this->update( $table, $set, $where, $fname );
2901                                 $affectedRowCount += $this->affectedRows();
2902                         }
2903                         # Now insert any non-conflicting row(s)
2904                         $this->insert( $table, $rows, $fname, [ 'IGNORE' ] );
2905                         $affectedRowCount += $this->affectedRows();
2906                         $this->endAtomic( $fname );
2907                         $this->affectedRowCount = $affectedRowCount;
2908                 } catch ( Exception $e ) {
2909                         $this->cancelAtomic( $fname );
2910                         throw $e;
2911                 }
2912
2913                 return true;
2914         }
2915
2916         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2917                 $fname = __METHOD__
2918         ) {
2919                 if ( !$conds ) {
2920                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2921                 }
2922
2923                 $delTable = $this->tableName( $delTable );
2924                 $joinTable = $this->tableName( $joinTable );
2925                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2926                 if ( $conds != '*' ) {
2927                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2928                 }
2929                 $sql .= ')';
2930
2931                 $this->query( $sql, $fname );
2932         }
2933
2934         public function textFieldSize( $table, $field ) {
2935                 $table = $this->tableName( $table );
2936                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2937                 $res = $this->query( $sql, __METHOD__ );
2938                 $row = $this->fetchObject( $res );
2939
2940                 $m = [];
2941
2942                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2943                         $size = $m[1];
2944                 } else {
2945                         $size = -1;
2946                 }
2947
2948                 return $size;
2949         }
2950
2951         public function delete( $table, $conds, $fname = __METHOD__ ) {
2952                 if ( !$conds ) {
2953                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2954                 }
2955
2956                 $table = $this->tableName( $table );
2957                 $sql = "DELETE FROM $table";
2958
2959                 if ( $conds != '*' ) {
2960                         if ( is_array( $conds ) ) {
2961                                 $conds = $this->makeList( $conds, self::LIST_AND );
2962                         }
2963                         $sql .= ' WHERE ' . $conds;
2964                 }
2965
2966                 $this->query( $sql, $fname );
2967
2968                 return true;
2969         }
2970
2971         final public function insertSelect(
2972                 $destTable, $srcTable, $varMap, $conds,
2973                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2974         ) {
2975                 static $hints = [ 'NO_AUTO_COLUMNS' ];
2976
2977                 $insertOptions = (array)$insertOptions;
2978                 $selectOptions = (array)$selectOptions;
2979
2980                 if ( $this->cliMode && $this->isInsertSelectSafe( $insertOptions, $selectOptions ) ) {
2981                         // For massive migrations with downtime, we don't want to select everything
2982                         // into memory and OOM, so do all this native on the server side if possible.
2983                         $this->nativeInsertSelect(
2984                                 $destTable,
2985                                 $srcTable,
2986                                 $varMap,
2987                                 $conds,
2988                                 $fname,
2989                                 array_diff( $insertOptions, $hints ),
2990                                 $selectOptions,
2991                                 $selectJoinConds
2992                         );
2993                 } else {
2994                         $this->nonNativeInsertSelect(
2995                                 $destTable,
2996                                 $srcTable,
2997                                 $varMap,
2998                                 $conds,
2999                                 $fname,
3000                                 array_diff( $insertOptions, $hints ),
3001                                 $selectOptions,
3002                                 $selectJoinConds
3003                         );
3004                 }
3005
3006                 return true;
3007         }
3008
3009         /**
3010          * @param array $insertOptions INSERT options
3011          * @param array $selectOptions SELECT options
3012          * @return bool Whether an INSERT SELECT with these options will be replication safe
3013          * @since 1.31
3014          */
3015         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
3016                 return true;
3017         }
3018
3019         /**
3020          * Implementation of insertSelect() based on select() and insert()
3021          *
3022          * @see IDatabase::insertSelect()
3023          * @since 1.30
3024          * @param string $destTable
3025          * @param string|array $srcTable
3026          * @param array $varMap
3027          * @param array $conds
3028          * @param string $fname
3029          * @param array $insertOptions
3030          * @param array $selectOptions
3031          * @param array $selectJoinConds
3032          */
3033         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3034                 $fname = __METHOD__,
3035                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3036         ) {
3037                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
3038                 // on only the master (without needing row-based-replication). It also makes it easy to
3039                 // know how big the INSERT is going to be.
3040                 $fields = [];
3041                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
3042                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
3043                 }
3044                 $selectOptions[] = 'FOR UPDATE';
3045                 $res = $this->select(
3046                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
3047                 );
3048                 if ( !$res ) {
3049                         return;
3050                 }
3051
3052                 try {
3053                         $affectedRowCount = 0;
3054                         $this->startAtomic( $fname, self::ATOMIC_CANCELABLE );
3055                         $rows = [];
3056                         $ok = true;
3057                         foreach ( $res as $row ) {
3058                                 $rows[] = (array)$row;
3059
3060                                 // Avoid inserts that are too huge
3061                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
3062                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3063                                         if ( !$ok ) {
3064                                                 break;
3065                                         }
3066                                         $affectedRowCount += $this->affectedRows();
3067                                         $rows = [];
3068                                 }
3069                         }
3070                         if ( $rows && $ok ) {
3071                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
3072                                 if ( $ok ) {
3073                                         $affectedRowCount += $this->affectedRows();
3074                                 }
3075                         }
3076                         if ( $ok ) {
3077                                 $this->endAtomic( $fname );
3078                                 $this->affectedRowCount = $affectedRowCount;
3079                         } else {
3080                                 $this->cancelAtomic( $fname );
3081                         }
3082                 } catch ( Exception $e ) {
3083                         $this->cancelAtomic( $fname );
3084                         throw $e;
3085                 }
3086         }
3087
3088         /**
3089          * Native server-side implementation of insertSelect() for situations where
3090          * we don't want to select everything into memory
3091          *
3092          * @see IDatabase::insertSelect()
3093          * @param string $destTable
3094          * @param string|array $srcTable
3095          * @param array $varMap
3096          * @param array $conds
3097          * @param string $fname
3098          * @param array $insertOptions
3099          * @param array $selectOptions
3100          * @param array $selectJoinConds
3101          */
3102         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
3103                 $fname = __METHOD__,
3104                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
3105         ) {
3106                 $destTable = $this->tableName( $destTable );
3107
3108                 if ( !is_array( $insertOptions ) ) {
3109                         $insertOptions = [ $insertOptions ];
3110                 }
3111
3112                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3113
3114                 $selectSql = $this->selectSQLText(
3115                         $srcTable,
3116                         array_values( $varMap ),
3117                         $conds,
3118                         $fname,
3119                         $selectOptions,
3120                         $selectJoinConds
3121                 );
3122
3123                 $sql = "INSERT $insertOptions" .
3124                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
3125                         $selectSql;
3126
3127                 $this->query( $sql, $fname );
3128         }
3129
3130         /**
3131          * Construct a LIMIT query with optional offset. This is used for query
3132          * pages. The SQL should be adjusted so that only the first $limit rows
3133          * are returned. If $offset is provided as well, then the first $offset
3134          * rows should be discarded, and the next $limit rows should be returned.
3135          * If the result of the query is not ordered, then the rows to be returned
3136          * are theoretically arbitrary.
3137          *
3138          * $sql is expected to be a SELECT, if that makes a difference.
3139          *
3140          * The version provided by default works in MySQL and SQLite. It will very
3141          * likely need to be overridden for most other DBMSes.
3142          *
3143          * @param string $sql SQL query we will append the limit too
3144          * @param int $limit The SQL limit
3145          * @param int|bool $offset The SQL offset (default false)
3146          * @throws DBUnexpectedError
3147          * @return string
3148          */
3149         public function limitResult( $sql, $limit, $offset = false ) {
3150                 if ( !is_numeric( $limit ) ) {
3151                         throw new DBUnexpectedError( $this,
3152                                 "Invalid non-numeric limit passed to limitResult()\n" );
3153                 }
3154
3155                 return "$sql LIMIT "
3156                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3157                 . "{$limit} ";
3158         }
3159
3160         public function unionSupportsOrderAndLimit() {
3161                 return true; // True for almost every DB supported
3162         }
3163
3164         public function unionQueries( $sqls, $all ) {
3165                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3166
3167                 return '(' . implode( $glue, $sqls ) . ')';
3168         }
3169
3170         public function unionConditionPermutations(
3171                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
3172                 $options = [], $join_conds = []
3173         ) {
3174                 // First, build the Cartesian product of $permute_conds
3175                 $conds = [ [] ];
3176                 foreach ( $permute_conds as $field => $values ) {
3177                         if ( !$values ) {
3178                                 // Skip empty $values
3179                                 continue;
3180                         }
3181                         $values = array_unique( $values ); // For sanity
3182                         $newConds = [];
3183                         foreach ( $conds as $cond ) {
3184                                 foreach ( $values as $value ) {
3185                                         $cond[$field] = $value;
3186                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
3187                                 }
3188                         }
3189                         $conds = $newConds;
3190                 }
3191
3192                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
3193
3194                 // If there's just one condition and no subordering, hand off to
3195                 // selectSQLText directly.
3196                 if ( count( $conds ) === 1 &&
3197                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
3198                 ) {
3199                         return $this->selectSQLText(
3200                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
3201                         );
3202                 }
3203
3204                 // Otherwise, we need to pull out the order and limit to apply after
3205                 // the union. Then build the SQL queries for each set of conditions in
3206                 // $conds. Then union them together (using UNION ALL, because the
3207                 // product *should* already be distinct).
3208                 $orderBy = $this->makeOrderBy( $options );
3209                 $limit = $options['LIMIT'] ?? null;
3210                 $offset = $options['OFFSET'] ?? false;
3211                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
3212                 if ( !$this->unionSupportsOrderAndLimit() ) {
3213                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
3214                 } else {
3215                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
3216                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
3217                         }
3218                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
3219                                 // We need to increase the limit by the offset rather than
3220                                 // using the offset directly, otherwise it'll skip incorrectly
3221                                 // in the subqueries.
3222                                 $options['LIMIT'] = $limit + $offset;
3223                                 unset( $options['OFFSET'] );
3224                         }
3225                 }
3226
3227                 $sqls = [];
3228                 foreach ( $conds as $cond ) {
3229                         $sqls[] = $this->selectSQLText(
3230                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
3231                         );
3232                 }
3233                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
3234                 if ( $limit !== null ) {
3235                         $sql = $this->limitResult( $sql, $limit, $offset );
3236                 }
3237
3238                 return $sql;
3239         }
3240
3241         public function conditional( $cond, $trueVal, $falseVal ) {
3242                 if ( is_array( $cond ) ) {
3243                         $cond = $this->makeList( $cond, self::LIST_AND );
3244                 }
3245
3246                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3247         }
3248
3249         public function strreplace( $orig, $old, $new ) {
3250                 return "REPLACE({$orig}, {$old}, {$new})";
3251         }
3252
3253         public function getServerUptime() {
3254                 return 0;
3255         }
3256
3257         public function wasDeadlock() {
3258                 return false;
3259         }
3260
3261         public function wasLockTimeout() {
3262                 return false;
3263         }
3264
3265         public function wasConnectionLoss() {
3266                 return $this->wasConnectionError( $this->lastErrno() );
3267         }
3268
3269         public function wasReadOnlyError() {
3270                 return false;
3271         }
3272
3273         public function wasErrorReissuable() {
3274                 return (
3275                         $this->wasDeadlock() ||
3276                         $this->wasLockTimeout() ||
3277                         $this->wasConnectionLoss()
3278                 );
3279         }
3280
3281         /**
3282          * Do not use this method outside of Database/DBError classes
3283          *
3284          * @param int|string $errno
3285          * @return bool Whether the given query error was a connection drop
3286          */
3287         public function wasConnectionError( $errno ) {
3288                 return false;
3289         }
3290
3291         /**
3292          * @return bool Whether it is safe to assume the given error only caused statement rollback
3293          * @note This is for backwards compatibility for callers catching DBError exceptions in
3294          *   order to ignore problems like duplicate key errors or foriegn key violations
3295          * @since 1.31
3296          */
3297         protected function wasKnownStatementRollbackError() {
3298                 return false; // don't know; it could have caused a transaction rollback
3299         }
3300
3301         public function deadlockLoop() {
3302                 $args = func_get_args();
3303                 $function = array_shift( $args );
3304                 $tries = self::DEADLOCK_TRIES;
3305
3306                 $this->begin( __METHOD__ );
3307
3308                 $retVal = null;
3309                 /** @var Exception $e */
3310                 $e = null;
3311                 do {
3312                         try {
3313                                 $retVal = $function( ...$args );
3314                                 break;
3315                         } catch ( DBQueryError $e ) {
3316                                 if ( $this->wasDeadlock() ) {
3317                                         // Retry after a randomized delay
3318                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3319                                 } else {
3320                                         // Throw the error back up
3321                                         throw $e;
3322                                 }
3323                         }
3324                 } while ( --$tries > 0 );
3325
3326                 if ( $tries <= 0 ) {
3327                         // Too many deadlocks; give up
3328                         $this->rollback( __METHOD__ );
3329                         throw $e;
3330                 } else {
3331                         $this->commit( __METHOD__ );
3332
3333                         return $retVal;
3334                 }
3335         }
3336
3337         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3338                 # Real waits are implemented in the subclass.
3339                 return 0;
3340         }
3341
3342         public function getReplicaPos() {
3343                 # Stub
3344                 return false;
3345         }
3346
3347         public function getMasterPos() {
3348                 # Stub
3349                 return false;
3350         }
3351
3352         public function serverIsReadOnly() {
3353                 return false;
3354         }
3355
3356         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
3357                 if ( !$this->trxLevel ) {
3358                         throw new DBUnexpectedError( $this, "No transaction is active." );
3359                 }
3360                 $this->trxEndCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3361         }
3362
3363         final public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3364                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3365                         // Start an implicit transaction similar to how query() does
3366                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3367                         $this->trxAutomatic = true;
3368                 }
3369
3370                 $this->trxIdleCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3371                 if ( !$this->trxLevel ) {
3372                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
3373                 }
3374         }
3375
3376         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
3377                 $this->onTransactionCommitOrIdle( $callback, $fname );
3378         }
3379
3380         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
3381                 if ( !$this->trxLevel && $this->getTransactionRoundId() ) {
3382                         // Start an implicit transaction similar to how query() does
3383                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
3384                         $this->trxAutomatic = true;
3385                 }
3386
3387                 if ( $this->trxLevel ) {
3388                         $this->trxPreCommitCallbacks[] = [ $callback, $fname, $this->currentAtomicSectionId() ];
3389                 } else {
3390                         // No transaction is active nor will start implicitly, so make one for this callback
3391                         $this->startAtomic( __METHOD__, self::ATOMIC_CANCELABLE );
3392                         try {
3393                                 $callback( $this );
3394                                 $this->endAtomic( __METHOD__ );
3395                         } catch ( Exception $e ) {
3396                                 $this->cancelAtomic( __METHOD__ );
3397                                 throw $e;
3398                         }
3399                 }
3400         }
3401
3402         /**
3403          * @return AtomicSectionIdentifier|null ID of the topmost atomic section level
3404          */
3405         private function currentAtomicSectionId() {
3406                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3407                         $levelInfo = end( $this->trxAtomicLevels );
3408
3409                         return $levelInfo[1];
3410                 }
3411
3412                 return null;
3413         }
3414
3415         /**
3416          * @param AtomicSectionIdentifier $old
3417          * @param AtomicSectionIdentifier $new
3418          */
3419         private function reassignCallbacksForSection(
3420                 AtomicSectionIdentifier $old, AtomicSectionIdentifier $new
3421         ) {
3422                 foreach ( $this->trxPreCommitCallbacks as $key => $info ) {
3423                         if ( $info[2] === $old ) {
3424                                 $this->trxPreCommitCallbacks[$key][2] = $new;
3425                         }
3426                 }
3427                 foreach ( $this->trxIdleCallbacks as $key => $info ) {
3428                         if ( $info[2] === $old ) {
3429                                 $this->trxIdleCallbacks[$key][2] = $new;
3430                         }
3431                 }
3432                 foreach ( $this->trxEndCallbacks as $key => $info ) {
3433                         if ( $info[2] === $old ) {
3434                                 $this->trxEndCallbacks[$key][2] = $new;
3435                         }
3436                 }
3437         }
3438
3439         /**
3440          * @param AtomicSectionIdentifier[] $sectionIds ID of an actual savepoint
3441          * @throws UnexpectedValueException
3442          */
3443         private function modifyCallbacksForCancel( array $sectionIds ) {
3444                 // Cancel the "on commit" callbacks owned by this savepoint
3445                 $this->trxIdleCallbacks = array_filter(
3446                         $this->trxIdleCallbacks,
3447                         function ( $entry ) use ( $sectionIds ) {
3448                                 return !in_array( $entry[2], $sectionIds, true );
3449                         }
3450                 );
3451                 $this->trxPreCommitCallbacks = array_filter(
3452                         $this->trxPreCommitCallbacks,
3453                         function ( $entry ) use ( $sectionIds ) {
3454                                 return !in_array( $entry[2], $sectionIds, true );
3455                         }
3456                 );
3457                 // Make "on resolution" callbacks owned by this savepoint to perceive a rollback
3458                 foreach ( $this->trxEndCallbacks as $key => $entry ) {
3459                         if ( in_array( $entry[2], $sectionIds, true ) ) {
3460                                 $callback = $entry[0];
3461                                 $this->trxEndCallbacks[$key][0] = function () use ( $callback ) {
3462                                         return $callback( self::TRIGGER_ROLLBACK, $this );
3463                                 };
3464                         }
3465                 }
3466         }
3467
3468         final public function setTransactionListener( $name, callable $callback = null ) {
3469                 if ( $callback ) {
3470                         $this->trxRecurringCallbacks[$name] = $callback;
3471                 } else {
3472                         unset( $this->trxRecurringCallbacks[$name] );
3473                 }
3474         }
3475
3476         /**
3477          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
3478          *
3479          * This method should not be used outside of Database/LoadBalancer
3480          *
3481          * @param bool $suppress
3482          * @since 1.28
3483          */
3484         final public function setTrxEndCallbackSuppression( $suppress ) {
3485                 $this->trxEndCallbacksSuppressed = $suppress;
3486         }
3487
3488         /**
3489          * Actually consume and run any "on transaction idle/resolution" callbacks.
3490          *
3491          * This method should not be used outside of Database/LoadBalancer
3492          *
3493          * @param int $trigger IDatabase::TRIGGER_* constant
3494          * @return int Number of callbacks attempted
3495          * @since 1.20
3496          * @throws Exception
3497          */
3498         public function runOnTransactionIdleCallbacks( $trigger ) {
3499                 if ( $this->trxLevel ) { // sanity
3500                         throw new DBUnexpectedError( $this, __METHOD__ . ': a transaction is still open.' );
3501                 }
3502
3503                 if ( $this->trxEndCallbacksSuppressed ) {
3504                         return 0;
3505                 }
3506
3507                 $count = 0;
3508                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
3509                 /** @var Exception $e */
3510                 $e = null; // first exception
3511                 do { // callbacks may add callbacks :)
3512                         $callbacks = array_merge(
3513                                 $this->trxIdleCallbacks,
3514                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
3515                         );
3516                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
3517                         $this->trxEndCallbacks = []; // consumed (recursion guard)
3518                         foreach ( $callbacks as $callback ) {
3519                                 ++$count;
3520                                 list( $phpCallback ) = $callback;
3521                                 $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
3522                                 try {
3523                                         call_user_func( $phpCallback, $trigger, $this );
3524                                 } catch ( Exception $ex ) {
3525                                         call_user_func( $this->errorLogger, $ex );
3526                                         $e = $e ?: $ex;
3527                                         // Some callbacks may use startAtomic/endAtomic, so make sure
3528                                         // their transactions are ended so other callbacks don't fail
3529                                         if ( $this->trxLevel() ) {
3530                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
3531                                         }
3532                                 } finally {
3533                                         if ( $autoTrx ) {
3534                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
3535                                         } else {
3536                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
3537                                         }
3538                                 }
3539                         }
3540                 } while ( count( $this->trxIdleCallbacks ) );
3541
3542                 if ( $e instanceof Exception ) {
3543                         throw $e; // re-throw any first exception
3544                 }
3545
3546                 return $count;
3547         }
3548
3549         /**
3550          * Actually consume and run any "on transaction pre-commit" callbacks.
3551          *
3552          * This method should not be used outside of Database/LoadBalancer
3553          *
3554          * @since 1.22
3555          * @return int Number of callbacks attempted
3556          * @throws Exception
3557          */
3558         public function runOnTransactionPreCommitCallbacks() {
3559                 $count = 0;
3560
3561                 $e = null; // first exception
3562                 do { // callbacks may add callbacks :)
3563                         $callbacks = $this->trxPreCommitCallbacks;
3564                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
3565                         foreach ( $callbacks as $callback ) {
3566                                 try {
3567                                         ++$count;
3568                                         list( $phpCallback ) = $callback;
3569                                         $phpCallback( $this );
3570                                 } catch ( Exception $ex ) {
3571                                         ( $this->errorLogger )( $ex );
3572                                         $e = $e ?: $ex;
3573                                 }
3574                         }
3575                 } while ( count( $this->trxPreCommitCallbacks ) );
3576
3577                 if ( $e instanceof Exception ) {
3578                         throw $e; // re-throw any first exception
3579                 }
3580
3581                 return $count;
3582         }
3583
3584         /**
3585          * Actually run any "transaction listener" callbacks.
3586          *
3587          * This method should not be used outside of Database/LoadBalancer
3588          *
3589          * @param int $trigger IDatabase::TRIGGER_* constant
3590          * @throws Exception
3591          * @since 1.20
3592          */
3593         public function runTransactionListenerCallbacks( $trigger ) {
3594                 if ( $this->trxEndCallbacksSuppressed ) {
3595                         return;
3596                 }
3597
3598                 /** @var Exception $e */
3599                 $e = null; // first exception
3600
3601                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
3602                         try {
3603                                 $phpCallback( $trigger, $this );
3604                         } catch ( Exception $ex ) {
3605                                 ( $this->errorLogger )( $ex );
3606                                 $e = $e ?: $ex;
3607                         }
3608                 }
3609
3610                 if ( $e instanceof Exception ) {
3611                         throw $e; // re-throw any first exception
3612                 }
3613         }
3614
3615         /**
3616          * Create a savepoint
3617          *
3618          * This is used internally to implement atomic sections. It should not be
3619          * used otherwise.
3620          *
3621          * @since 1.31
3622          * @param string $identifier Identifier for the savepoint
3623          * @param string $fname Calling function name
3624          */
3625         protected function doSavepoint( $identifier, $fname ) {
3626                 $this->query( 'SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3627         }
3628
3629         /**
3630          * Release a savepoint
3631          *
3632          * This is used internally to implement atomic sections. It should not be
3633          * used otherwise.
3634          *
3635          * @since 1.31
3636          * @param string $identifier Identifier for the savepoint
3637          * @param string $fname Calling function name
3638          */
3639         protected function doReleaseSavepoint( $identifier, $fname ) {
3640                 $this->query( 'RELEASE SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3641         }
3642
3643         /**
3644          * Rollback to a savepoint
3645          *
3646          * This is used internally to implement atomic sections. It should not be
3647          * used otherwise.
3648          *
3649          * @since 1.31
3650          * @param string $identifier Identifier for the savepoint
3651          * @param string $fname Calling function name
3652          */
3653         protected function doRollbackToSavepoint( $identifier, $fname ) {
3654                 $this->query( 'ROLLBACK TO SAVEPOINT ' . $this->addIdentifierQuotes( $identifier ), $fname );
3655         }
3656
3657         /**
3658          * @param string $fname
3659          * @return string
3660          */
3661         private function nextSavepointId( $fname ) {
3662                 $savepointId = self::$SAVEPOINT_PREFIX . ++$this->trxAtomicCounter;
3663                 if ( strlen( $savepointId ) > 30 ) {
3664                         // 30 == Oracle's identifier length limit (pre 12c)
3665                         // With a 22 character prefix, that puts the highest number at 99999999.
3666                         throw new DBUnexpectedError(
3667                                 $this,
3668                                 'There have been an excessively large number of atomic sections in a transaction'
3669                                 . " started by $this->trxFname (at $fname)"
3670                         );
3671                 }
3672
3673                 return $savepointId;
3674         }
3675
3676         final public function startAtomic(
3677                 $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE
3678         ) {
3679                 $savepointId = $cancelable === self::ATOMIC_CANCELABLE ? self::$NOT_APPLICABLE : null;
3680
3681                 if ( !$this->trxLevel ) {
3682                         $this->begin( $fname, self::TRANSACTION_INTERNAL ); // sets trxAutomatic
3683                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3684                         // in all changes being in one transaction to keep requests transactional.
3685                         if ( $this->getFlag( self::DBO_TRX ) ) {
3686                                 // Since writes could happen in between the topmost atomic sections as part
3687                                 // of the transaction, those sections will need savepoints.
3688                                 $savepointId = $this->nextSavepointId( $fname );
3689                                 $this->doSavepoint( $savepointId, $fname );
3690                         } else {
3691                                 $this->trxAutomaticAtomic = true;
3692                         }
3693                 } elseif ( $cancelable === self::ATOMIC_CANCELABLE ) {
3694                         $savepointId = $this->nextSavepointId( $fname );
3695                         $this->doSavepoint( $savepointId, $fname );
3696                 }
3697
3698                 $sectionId = new AtomicSectionIdentifier;
3699                 $this->trxAtomicLevels[] = [ $fname, $sectionId, $savepointId ];
3700                 $this->queryLogger->debug( 'startAtomic: entering level ' .
3701                         ( count( $this->trxAtomicLevels ) - 1 ) . " ($fname)" );
3702
3703                 return $sectionId;
3704         }
3705
3706         final public function endAtomic( $fname = __METHOD__ ) {
3707                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3708                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3709                 }
3710
3711                 // Check if the current section matches $fname
3712                 $pos = count( $this->trxAtomicLevels ) - 1;
3713                 list( $savedFname, $sectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3714                 $this->queryLogger->debug( "endAtomic: leaving level $pos ($fname)" );
3715
3716                 if ( $savedFname !== $fname ) {
3717                         throw new DBUnexpectedError(
3718                                 $this,
3719                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3720                         );
3721                 }
3722
3723                 // Remove the last section (no need to re-index the array)
3724                 array_pop( $this->trxAtomicLevels );
3725
3726                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
3727                         $this->commit( $fname, self::FLUSHING_INTERNAL );
3728                 } elseif ( $savepointId !== null && $savepointId !== self::$NOT_APPLICABLE ) {
3729                         $this->doReleaseSavepoint( $savepointId, $fname );
3730                 }
3731
3732                 // Hoist callback ownership for callbacks in the section that just ended;
3733                 // all callbacks should have an owner that is present in trxAtomicLevels.
3734                 $currentSectionId = $this->currentAtomicSectionId();
3735                 if ( $currentSectionId ) {
3736                         $this->reassignCallbacksForSection( $sectionId, $currentSectionId );
3737                 }
3738         }
3739
3740         final public function cancelAtomic(
3741                 $fname = __METHOD__, AtomicSectionIdentifier $sectionId = null
3742         ) {
3743                 if ( !$this->trxLevel || !$this->trxAtomicLevels ) {
3744                         throw new DBUnexpectedError( $this, "No atomic section is open (got $fname)." );
3745                 }
3746
3747                 $excisedFnames = [];
3748                 if ( $sectionId !== null ) {
3749                         // Find the (last) section with the given $sectionId
3750                         $pos = -1;
3751                         foreach ( $this->trxAtomicLevels as $i => list( $asFname, $asId, $spId ) ) {
3752                                 if ( $asId === $sectionId ) {
3753                                         $pos = $i;
3754                                 }
3755                         }
3756                         if ( $pos < 0 ) {
3757                                 throw new DBUnexpectedError( $this, "Atomic section not found (for $fname)" );
3758                         }
3759                         // Remove all descendant sections and re-index the array
3760                         $excisedIds = [];
3761                         $len = count( $this->trxAtomicLevels );
3762                         for ( $i = $pos + 1; $i < $len; ++$i ) {
3763                                 $excisedFnames[] = $this->trxAtomicLevels[$i][0];
3764                                 $excisedIds[] = $this->trxAtomicLevels[$i][1];
3765                         }
3766                         $this->trxAtomicLevels = array_slice( $this->trxAtomicLevels, 0, $pos + 1 );
3767                         $this->modifyCallbacksForCancel( $excisedIds );
3768                 }
3769
3770                 // Check if the current section matches $fname
3771                 $pos = count( $this->trxAtomicLevels ) - 1;
3772                 list( $savedFname, $savedSectionId, $savepointId ) = $this->trxAtomicLevels[$pos];
3773
3774                 if ( $excisedFnames ) {
3775                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname) " .
3776                                 "and descendants " . implode( ', ', $excisedFnames ) );
3777                 } else {
3778                         $this->queryLogger->debug( "cancelAtomic: canceling level $pos ($savedFname)" );
3779                 }
3780
3781                 if ( $savedFname !== $fname ) {
3782                         throw new DBUnexpectedError(
3783                                 $this,
3784                                 "Invalid atomic section ended (got $fname but expected $savedFname)."
3785                         );
3786                 }
3787
3788                 // Remove the last section (no need to re-index the array)
3789                 array_pop( $this->trxAtomicLevels );
3790                 $this->modifyCallbacksForCancel( [ $savedSectionId ] );
3791
3792                 if ( $savepointId !== null ) {
3793                         // Rollback the transaction to the state just before this atomic section
3794                         if ( $savepointId === self::$NOT_APPLICABLE ) {
3795                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
3796                         } else {
3797                                 $this->doRollbackToSavepoint( $savepointId, $fname );
3798                                 $this->trxStatus = self::STATUS_TRX_OK; // no exception; recovered
3799                                 $this->trxStatusIgnoredCause = null;
3800                         }
3801                 } elseif ( $this->trxStatus > self::STATUS_TRX_ERROR ) {
3802                         // Put the transaction into an error state if it's not already in one
3803                         $this->trxStatus = self::STATUS_TRX_ERROR;
3804                         $this->trxStatusCause = new DBUnexpectedError(
3805                                 $this,
3806                                 "Uncancelable atomic section canceled (got $fname)."
3807                         );
3808                 }
3809
3810                 $this->affectedRowCount = 0; // for the sake of consistency
3811         }
3812
3813         final public function doAtomicSection(
3814                 $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
3815         ) {
3816                 $sectionId = $this->startAtomic( $fname, $cancelable );
3817                 try {
3818                         $res = $callback( $this, $fname );
3819                 } catch ( Exception $e ) {
3820                         $this->cancelAtomic( $fname, $sectionId );
3821
3822                         throw $e;
3823                 }
3824                 $this->endAtomic( $fname );
3825
3826                 return $res;
3827         }
3828
3829         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3830                 static $modes = [ self::TRANSACTION_EXPLICIT, self::TRANSACTION_INTERNAL ];
3831                 if ( !in_array( $mode, $modes, true ) ) {
3832                         throw new DBUnexpectedError( $this, "$fname: invalid mode parameter '$mode'." );
3833                 }
3834
3835                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3836                 if ( $this->trxLevel ) {
3837                         if ( $this->trxAtomicLevels ) {
3838                                 $levels = $this->flatAtomicSectionList();
3839                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3840                                 throw new DBUnexpectedError( $this, $msg );
3841                         } elseif ( !$this->trxAutomatic ) {
3842                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3843                                 throw new DBUnexpectedError( $this, $msg );
3844                         } else {
3845                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3846                                 throw new DBUnexpectedError( $this, $msg );
3847                         }
3848                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3849                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3850                         throw new DBUnexpectedError( $this, $msg );
3851                 }
3852
3853                 // Avoid fatals if close() was called
3854                 $this->assertOpen();
3855
3856                 $this->doBegin( $fname );
3857                 $this->trxStatus = self::STATUS_TRX_OK;
3858                 $this->trxStatusIgnoredCause = null;
3859                 $this->trxAtomicCounter = 0;
3860                 $this->trxTimestamp = microtime( true );
3861                 $this->trxFname = $fname;
3862                 $this->trxDoneWrites = false;
3863                 $this->trxAutomaticAtomic = false;
3864                 $this->trxAtomicLevels = [];
3865                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3866                 $this->trxWriteDuration = 0.0;
3867                 $this->trxWriteQueryCount = 0;
3868                 $this->trxWriteAffectedRows = 0;
3869                 $this->trxWriteAdjDuration = 0.0;
3870                 $this->trxWriteAdjQueryCount = 0;
3871                 $this->trxWriteCallers = [];
3872                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3873                 // Get an estimate of the replication lag before any such queries.
3874                 $this->trxReplicaLag = null; // clear cached value first
3875                 $this->trxReplicaLag = $this->getApproximateLagStatus()['lag'];
3876                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3877                 // caller will think its OK to muck around with the transaction just because startAtomic()
3878                 // has not yet completed (e.g. setting trxAtomicLevels).
3879                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3880         }
3881
3882         /**
3883          * Issues the BEGIN command to the database server.
3884          *
3885          * @see Database::begin()
3886          * @param string $fname
3887          */
3888         protected function doBegin( $fname ) {
3889                 $this->query( 'BEGIN', $fname );
3890                 $this->trxLevel = 1;
3891         }
3892
3893         final public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE ) {
3894                 static $modes = [ self::FLUSHING_ONE, self::FLUSHING_ALL_PEERS, self::FLUSHING_INTERNAL ];
3895                 if ( !in_array( $flush, $modes, true ) ) {
3896                         throw new DBUnexpectedError( $this, "$fname: invalid flush parameter '$flush'." );
3897                 }
3898
3899                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3900                         // There are still atomic sections open; this cannot be ignored
3901                         $levels = $this->flatAtomicSectionList();
3902                         throw new DBUnexpectedError(
3903                                 $this,
3904                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3905                         );
3906                 }
3907
3908                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3909                         if ( !$this->trxLevel ) {
3910                                 return; // nothing to do
3911                         } elseif ( !$this->trxAutomatic ) {
3912                                 throw new DBUnexpectedError(
3913                                         $this,
3914                                         "$fname: Flushing an explicit transaction, getting out of sync."
3915                                 );
3916                         }
3917                 } else {
3918                         if ( !$this->trxLevel ) {
3919                                 $this->queryLogger->error(
3920                                         "$fname: No transaction to commit, something got out of sync." );
3921                                 return; // nothing to do
3922                         } elseif ( $this->trxAutomatic ) {
3923                                 throw new DBUnexpectedError(
3924                                         $this,
3925                                         "$fname: Expected mass commit of all peer transactions (DBO_TRX set)."
3926                                 );
3927                         }
3928                 }
3929
3930                 // Avoid fatals if close() was called
3931                 $this->assertOpen();
3932
3933                 $this->runOnTransactionPreCommitCallbacks();
3934
3935                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3936                 $this->doCommit( $fname );
3937                 $this->trxStatus = self::STATUS_TRX_NONE;
3938
3939                 if ( $this->trxDoneWrites ) {
3940                         $this->lastWriteTime = microtime( true );
3941                         $this->trxProfiler->transactionWritingOut(
3942                                 $this->server,
3943                                 $this->getDomainID(),
3944                                 $this->trxShortId,
3945                                 $writeTime,
3946                                 $this->trxWriteAffectedRows
3947                         );
3948                 }
3949
3950                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
3951                 if ( $flush !== self::FLUSHING_ALL_PEERS ) {
3952                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3953                         $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3954                 }
3955         }
3956
3957         /**
3958          * Issues the COMMIT command to the database server.
3959          *
3960          * @see Database::commit()
3961          * @param string $fname
3962          */
3963         protected function doCommit( $fname ) {
3964                 if ( $this->trxLevel ) {
3965                         $this->query( 'COMMIT', $fname );
3966                         $this->trxLevel = 0;
3967                 }
3968         }
3969
3970         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3971                 $trxActive = $this->trxLevel;
3972
3973                 if ( $flush !== self::FLUSHING_INTERNAL && $flush !== self::FLUSHING_ALL_PEERS ) {
3974                         if ( $this->getFlag( self::DBO_TRX ) ) {
3975                                 throw new DBUnexpectedError(
3976                                         $this,
3977                                         "$fname: Expected mass rollback of all peer transactions (DBO_TRX set)."
3978                                 );
3979                         }
3980                 }
3981
3982                 if ( $trxActive ) {
3983                         // Avoid fatals if close() was called
3984                         $this->assertOpen();
3985
3986                         $this->doRollback( $fname );
3987                         $this->trxStatus = self::STATUS_TRX_NONE;
3988                         $this->trxAtomicLevels = [];
3989                         // Estimate the RTT via a query now that trxStatus is OK
3990                         $writeTime = $this->pingAndCalculateLastTrxApplyTime();
3991
3992                         if ( $this->trxDoneWrites ) {
3993                                 $this->trxProfiler->transactionWritingOut(
3994                                         $this->server,
3995                                         $this->getDomainID(),
3996                                         $this->trxShortId,
3997                                         $writeTime,
3998                                         $this->trxWriteAffectedRows
3999                                 );
4000                         }
4001                 }
4002
4003                 // Clear any commit-dependant callbacks. They might even be present
4004                 // only due to transaction rounds, with no SQL transaction being active
4005                 $this->trxIdleCallbacks = [];
4006                 $this->trxPreCommitCallbacks = [];
4007
4008                 // With FLUSHING_ALL_PEERS, callbacks will be explicitly run later
4009                 if ( $trxActive && $flush !== self::FLUSHING_ALL_PEERS ) {
4010                         try {
4011                                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
4012                         } catch ( Exception $e ) {
4013                                 // already logged; finish and let LoadBalancer move on during mass-rollback
4014                         }
4015                         try {
4016                                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
4017                         } catch ( Exception $e ) {
4018                                 // already logged; let LoadBalancer move on during mass-rollback
4019                         }
4020
4021                         $this->affectedRowCount = 0; // for the sake of consistency
4022                 }
4023         }
4024
4025         /**
4026          * Issues the ROLLBACK command to the database server.
4027          *
4028          * @see Database::rollback()
4029          * @param string $fname
4030          */
4031         protected function doRollback( $fname ) {
4032                 if ( $this->trxLevel ) {
4033                         # Disconnects cause rollback anyway, so ignore those errors
4034                         $ignoreErrors = true;
4035                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
4036                         $this->trxLevel = 0;
4037                 }
4038         }
4039
4040         public function flushSnapshot( $fname = __METHOD__ ) {
4041                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
4042                         // This only flushes transactions to clear snapshots, not to write data
4043                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4044                         throw new DBUnexpectedError(
4045                                 $this,
4046                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
4047                         );
4048                 }
4049
4050                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4051         }
4052
4053         public function explicitTrxActive() {
4054                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
4055         }
4056
4057         public function duplicateTableStructure(
4058                 $oldName, $newName, $temporary = false, $fname = __METHOD__
4059         ) {
4060                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4061         }
4062
4063         public function listTables( $prefix = null, $fname = __METHOD__ ) {
4064                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4065         }
4066
4067         public function listViews( $prefix = null, $fname = __METHOD__ ) {
4068                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
4069         }
4070
4071         public function timestamp( $ts = 0 ) {
4072                 $t = new ConvertibleTimestamp( $ts );
4073                 // Let errors bubble up to avoid putting garbage in the DB
4074                 return $t->getTimestamp( TS_MW );
4075         }
4076
4077         public function timestampOrNull( $ts = null ) {
4078                 if ( is_null( $ts ) ) {
4079                         return null;
4080                 } else {
4081                         return $this->timestamp( $ts );
4082                 }
4083         }
4084
4085         public function affectedRows() {
4086                 return ( $this->affectedRowCount === null )
4087                         ? $this->fetchAffectedRowCount() // default to driver value
4088                         : $this->affectedRowCount;
4089         }
4090
4091         /**
4092          * @return int Number of retrieved rows according to the driver
4093          */
4094         abstract protected function fetchAffectedRowCount();
4095
4096         /**
4097          * Take the result from a query, and wrap it in a ResultWrapper if
4098          * necessary. Boolean values are passed through as is, to indicate success
4099          * of write queries or failure.
4100          *
4101          * Once upon a time, Database::query() returned a bare MySQL result
4102          * resource, and it was necessary to call this function to convert it to
4103          * a wrapper. Nowadays, raw database objects are never exposed to external
4104          * callers, so this is unnecessary in external code.
4105          *
4106          * @param bool|ResultWrapper|resource $result
4107          * @return bool|ResultWrapper
4108          */
4109         protected function resultObject( $result ) {
4110                 if ( !$result ) {
4111                         return false;
4112                 } elseif ( $result instanceof ResultWrapper ) {
4113                         return $result;
4114                 } elseif ( $result === true ) {
4115                         // Successful write query
4116                         return $result;
4117                 } else {
4118                         return new ResultWrapper( $this, $result );
4119                 }
4120         }
4121
4122         public function ping( &$rtt = null ) {
4123                 // Avoid hitting the server if it was hit recently
4124                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
4125                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
4126                                 $rtt = $this->rttEstimate;
4127                                 return true; // don't care about $rtt
4128                         }
4129                 }
4130
4131                 // This will reconnect if possible or return false if not
4132                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
4133                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
4134                 $this->restoreFlags( self::RESTORE_PRIOR );
4135
4136                 if ( $ok ) {
4137                         $rtt = $this->rttEstimate;
4138                 }
4139
4140                 return $ok;
4141         }
4142
4143         /**
4144          * Close any existing (dead) database connection and open a new connection
4145          *
4146          * @param string $fname
4147          * @return bool True if new connection is opened successfully, false if error
4148          */
4149         protected function replaceLostConnection( $fname ) {
4150                 $this->closeConnection();
4151                 $this->opened = false;
4152                 $this->conn = false;
4153                 try {
4154                         $this->open(
4155                                 $this->server,
4156                                 $this->user,
4157                                 $this->password,
4158                                 $this->getDBname(),
4159                                 $this->dbSchema(),
4160                                 $this->tablePrefix()
4161                         );
4162                         $this->lastPing = microtime( true );
4163                         $ok = true;
4164
4165                         $this->connLogger->warning(
4166                                 $fname . ': lost connection to {dbserver}; reconnected',
4167                                 [
4168                                         'dbserver' => $this->getServer(),
4169                                         'trace' => ( new RuntimeException() )->getTraceAsString()
4170                                 ]
4171                         );
4172                 } catch ( DBConnectionError $e ) {
4173                         $ok = false;
4174
4175                         $this->connLogger->error(
4176                                 $fname . ': lost connection to {dbserver} permanently',
4177                                 [ 'dbserver' => $this->getServer() ]
4178                         );
4179                 }
4180
4181                 $this->handleSessionLoss();
4182
4183                 return $ok;
4184         }
4185
4186         public function getSessionLagStatus() {
4187                 return $this->getRecordedTransactionLagStatus() ?: $this->getApproximateLagStatus();
4188         }
4189
4190         /**
4191          * Get the replica DB lag when the current transaction started
4192          *
4193          * This is useful when transactions might use snapshot isolation
4194          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
4195          * is this lag plus transaction duration. If they don't, it is still
4196          * safe to be pessimistic. This returns null if there is no transaction.
4197          *
4198          * This returns null if the lag status for this transaction was not yet recorded.
4199          *
4200          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
4201          * @since 1.27
4202          */
4203         final protected function getRecordedTransactionLagStatus() {
4204                 return ( $this->trxLevel && $this->trxReplicaLag !== null )
4205                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
4206                         : null;
4207         }
4208
4209         /**
4210          * Get a replica DB lag estimate for this server
4211          *
4212          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
4213          * @since 1.27
4214          */
4215         protected function getApproximateLagStatus() {
4216                 return [
4217                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
4218                         'since' => microtime( true )
4219                 ];
4220         }
4221
4222         /**
4223          * Merge the result of getSessionLagStatus() for several DBs
4224          * using the most pessimistic values to estimate the lag of
4225          * any data derived from them in combination
4226          *
4227          * This is information is useful for caching modules
4228          *
4229          * @see WANObjectCache::set()
4230          * @see WANObjectCache::getWithSetCallback()
4231          *
4232          * @param IDatabase $db1
4233          * @param IDatabase|null $db2 [optional]
4234          * @return array Map of values:
4235          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
4236          *   - since: oldest UNIX timestamp of any of the DB lag estimates
4237          *   - pending: whether any of the DBs have uncommitted changes
4238          * @throws DBError
4239          * @since 1.27
4240          */
4241         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
4242                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
4243                 foreach ( func_get_args() as $db ) {
4244                         /** @var IDatabase $db */
4245                         $status = $db->getSessionLagStatus();
4246                         if ( $status['lag'] === false ) {
4247                                 $res['lag'] = false;
4248                         } elseif ( $res['lag'] !== false ) {
4249                                 $res['lag'] = max( $res['lag'], $status['lag'] );
4250                         }
4251                         $res['since'] = min( $res['since'], $status['since'] );
4252                         $res['pending'] = $res['pending'] ?: $db->writesPending();
4253                 }
4254
4255                 return $res;
4256         }
4257
4258         public function getLag() {
4259                 return 0;
4260         }
4261
4262         public function maxListLen() {
4263                 return 0;
4264         }
4265
4266         public function encodeBlob( $b ) {
4267                 return $b;
4268         }
4269
4270         public function decodeBlob( $b ) {
4271                 if ( $b instanceof Blob ) {
4272                         $b = $b->fetch();
4273                 }
4274                 return $b;
4275         }
4276
4277         public function setSessionOptions( array $options ) {
4278         }
4279
4280         public function sourceFile(
4281                 $filename,
4282                 callable $lineCallback = null,
4283                 callable $resultCallback = null,
4284                 $fname = false,
4285                 callable $inputCallback = null
4286         ) {
4287                 Wikimedia\suppressWarnings();
4288                 $fp = fopen( $filename, 'r' );
4289                 Wikimedia\restoreWarnings();
4290
4291                 if ( $fp === false ) {
4292                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
4293                 }
4294
4295                 if ( !$fname ) {
4296                         $fname = __METHOD__ . "( $filename )";
4297                 }
4298
4299                 try {
4300                         $error = $this->sourceStream(
4301                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4302                 } catch ( Exception $e ) {
4303                         fclose( $fp );
4304                         throw $e;
4305                 }
4306
4307                 fclose( $fp );
4308
4309                 return $error;
4310         }
4311
4312         public function setSchemaVars( $vars ) {
4313                 $this->schemaVars = $vars;
4314         }
4315
4316         public function sourceStream(
4317                 $fp,
4318                 callable $lineCallback = null,
4319                 callable $resultCallback = null,
4320                 $fname = __METHOD__,
4321                 callable $inputCallback = null
4322         ) {
4323                 $delimiterReset = new ScopedCallback(
4324                         function ( $delimiter ) {
4325                                 $this->delimiter = $delimiter;
4326                         },
4327                         [ $this->delimiter ]
4328                 );
4329                 $cmd = '';
4330
4331                 while ( !feof( $fp ) ) {
4332                         if ( $lineCallback ) {
4333                                 call_user_func( $lineCallback );
4334                         }
4335
4336                         $line = trim( fgets( $fp ) );
4337
4338                         if ( $line == '' ) {
4339                                 continue;
4340                         }
4341
4342                         if ( $line[0] == '-' && $line[1] == '-' ) {
4343                                 continue;
4344                         }
4345
4346                         if ( $cmd != '' ) {
4347                                 $cmd .= ' ';
4348                         }
4349
4350                         $done = $this->streamStatementEnd( $cmd, $line );
4351
4352                         $cmd .= "$line\n";
4353
4354                         if ( $done || feof( $fp ) ) {
4355                                 $cmd = $this->replaceVars( $cmd );
4356
4357                                 if ( $inputCallback ) {
4358                                         $callbackResult = $inputCallback( $cmd );
4359
4360                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
4361                                                 $cmd = $callbackResult;
4362                                         }
4363                                 }
4364
4365                                 if ( $cmd ) {
4366                                         $res = $this->query( $cmd, $fname );
4367
4368                                         if ( $resultCallback ) {
4369                                                 $resultCallback( $res, $this );
4370                                         }
4371
4372                                         if ( $res === false ) {
4373                                                 $err = $this->lastError();
4374
4375                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4376                                         }
4377                                 }
4378                                 $cmd = '';
4379                         }
4380                 }
4381
4382                 ScopedCallback::consume( $delimiterReset );
4383                 return true;
4384         }
4385
4386         /**
4387          * Called by sourceStream() to check if we've reached a statement end
4388          *
4389          * @param string &$sql SQL assembled so far
4390          * @param string &$newLine New line about to be added to $sql
4391          * @return bool Whether $newLine contains end of the statement
4392          */
4393         public function streamStatementEnd( &$sql, &$newLine ) {
4394                 if ( $this->delimiter ) {
4395                         $prev = $newLine;
4396                         $newLine = preg_replace(
4397                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4398                         if ( $newLine != $prev ) {
4399                                 return true;
4400                         }
4401                 }
4402
4403                 return false;
4404         }
4405
4406         /**
4407          * Database independent variable replacement. Replaces a set of variables
4408          * in an SQL statement with their contents as given by $this->getSchemaVars().
4409          *
4410          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4411          *
4412          * - '{$var}' should be used for text and is passed through the database's
4413          *   addQuotes method.
4414          * - `{$var}` should be used for identifiers (e.g. table and database names).
4415          *   It is passed through the database's addIdentifierQuotes method which
4416          *   can be overridden if the database uses something other than backticks.
4417          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4418          *   database's tableName method.
4419          * - / *i* / passes the name that follows through the database's indexName method.
4420          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4421          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4422          *
4423          * @param string $ins SQL statement to replace variables in
4424          * @return string The new SQL statement with variables replaced
4425          */
4426         protected function replaceVars( $ins ) {
4427                 $vars = $this->getSchemaVars();
4428                 return preg_replace_callback(
4429                         '!
4430                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4431                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4432                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4433                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4434                         !x',
4435                         function ( $m ) use ( $vars ) {
4436                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4437                                 // check for both nonexistent keys *and* the empty string.
4438                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4439                                         if ( $m[1] === 'i' ) {
4440                                                 return $this->indexName( $m[2] );
4441                                         } else {
4442                                                 return $this->tableName( $m[2] );
4443                                         }
4444                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4445                                         return $this->addQuotes( $vars[$m[3]] );
4446                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4447                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
4448                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4449                                         return $vars[$m[5]];
4450                                 } else {
4451                                         return $m[0];
4452                                 }
4453                         },
4454                         $ins
4455                 );
4456         }
4457
4458         /**
4459          * Get schema variables. If none have been set via setSchemaVars(), then
4460          * use some defaults from the current object.
4461          *
4462          * @return array
4463          */
4464         protected function getSchemaVars() {
4465                 if ( $this->schemaVars ) {
4466                         return $this->schemaVars;
4467                 } else {
4468                         return $this->getDefaultSchemaVars();
4469                 }
4470         }
4471
4472         /**
4473          * Get schema variables to use if none have been set via setSchemaVars().
4474          *
4475          * Override this in derived classes to provide variables for tables.sql
4476          * and SQL patch files.
4477          *
4478          * @return array
4479          */
4480         protected function getDefaultSchemaVars() {
4481                 return [];
4482         }
4483
4484         public function lockIsFree( $lockName, $method ) {
4485                 // RDBMs methods for checking named locks may or may not count this thread itself.
4486                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
4487                 // the behavior choosen by the interface for this method.
4488                 return !isset( $this->namedLocksHeld[$lockName] );
4489         }
4490
4491         public function lock( $lockName, $method, $timeout = 5 ) {
4492                 $this->namedLocksHeld[$lockName] = 1;
4493
4494                 return true;
4495         }
4496
4497         public function unlock( $lockName, $method ) {
4498                 unset( $this->namedLocksHeld[$lockName] );
4499
4500                 return true;
4501         }
4502
4503         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
4504                 if ( $this->writesOrCallbacksPending() ) {
4505                         // This only flushes transactions to clear snapshots, not to write data
4506                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
4507                         throw new DBUnexpectedError(
4508                                 $this,
4509                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
4510                         );
4511                 }
4512
4513                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
4514                         return null;
4515                 }
4516
4517                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
4518                         if ( $this->trxLevel() ) {
4519                                 // There is a good chance an exception was thrown, causing any early return
4520                                 // from the caller. Let any error handler get a chance to issue rollback().
4521                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
4522                                 $this->onTransactionResolution(
4523                                         function () use ( $lockKey, $fname ) {
4524                                                 $this->unlock( $lockKey, $fname );
4525                                         },
4526                                         $fname
4527                                 );
4528                         } else {
4529                                 $this->unlock( $lockKey, $fname );
4530                         }
4531                 } );
4532
4533                 $this->commit( $fname, self::FLUSHING_INTERNAL );
4534
4535                 return $unlocker;
4536         }
4537
4538         public function namedLocksEnqueue() {
4539                 return false;
4540         }
4541
4542         public function tableLocksHaveTransactionScope() {
4543                 return true;
4544         }
4545
4546         final public function lockTables( array $read, array $write, $method ) {
4547                 if ( $this->writesOrCallbacksPending() ) {
4548                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
4549                 }
4550
4551                 if ( $this->tableLocksHaveTransactionScope() ) {
4552                         $this->startAtomic( $method );
4553                 }
4554
4555                 return $this->doLockTables( $read, $write, $method );
4556         }
4557
4558         /**
4559          * Helper function for lockTables() that handles the actual table locking
4560          *
4561          * @param array $read Array of tables to lock for read access
4562          * @param array $write Array of tables to lock for write access
4563          * @param string $method Name of caller
4564          * @return true
4565          */
4566         protected function doLockTables( array $read, array $write, $method ) {
4567                 return true;
4568         }
4569
4570         final public function unlockTables( $method ) {
4571                 if ( $this->tableLocksHaveTransactionScope() ) {
4572                         $this->endAtomic( $method );
4573
4574                         return true; // locks released on COMMIT/ROLLBACK
4575                 }
4576
4577                 return $this->doUnlockTables( $method );
4578         }
4579
4580         /**
4581          * Helper function for unlockTables() that handles the actual table unlocking
4582          *
4583          * @param string $method Name of caller
4584          * @return true
4585          */
4586         protected function doUnlockTables( $method ) {
4587                 return true;
4588         }
4589
4590         /**
4591          * Delete a table
4592          * @param string $tableName
4593          * @param string $fName
4594          * @return bool|ResultWrapper
4595          * @since 1.18
4596          */
4597         public function dropTable( $tableName, $fName = __METHOD__ ) {
4598                 if ( !$this->tableExists( $tableName, $fName ) ) {
4599                         return false;
4600                 }
4601                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
4602
4603                 return $this->query( $sql, $fName );
4604         }
4605
4606         public function getInfinity() {
4607                 return 'infinity';
4608         }
4609
4610         public function encodeExpiry( $expiry ) {
4611                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4612                         ? $this->getInfinity()
4613                         : $this->timestamp( $expiry );
4614         }
4615
4616         public function decodeExpiry( $expiry, $format = TS_MW ) {
4617                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
4618                         return 'infinity';
4619                 }
4620
4621                 return ConvertibleTimestamp::convert( $format, $expiry );
4622         }
4623
4624         public function setBigSelects( $value = true ) {
4625                 // no-op
4626         }
4627
4628         public function isReadOnly() {
4629                 return ( $this->getReadOnlyReason() !== false );
4630         }
4631
4632         /**
4633          * @return string|bool Reason this DB is read-only or false if it is not
4634          */
4635         protected function getReadOnlyReason() {
4636                 $reason = $this->getLBInfo( 'readOnlyReason' );
4637
4638                 return is_string( $reason ) ? $reason : false;
4639         }
4640
4641         public function setTableAliases( array $aliases ) {
4642                 $this->tableAliases = $aliases;
4643         }
4644
4645         public function setIndexAliases( array $aliases ) {
4646                 $this->indexAliases = $aliases;
4647         }
4648
4649         /**
4650          * Get the underlying binding connection handle
4651          *
4652          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
4653          * This catches broken callers than catch and ignore disconnection exceptions.
4654          * Unlike checking isOpen(), this is safe to call inside of open().
4655          *
4656          * @return mixed
4657          * @throws DBUnexpectedError
4658          * @since 1.26
4659          */
4660         protected function getBindingHandle() {
4661                 if ( !$this->conn ) {
4662                         throw new DBUnexpectedError(
4663                                 $this,
4664                                 'DB connection was already closed or the connection dropped.'
4665                         );
4666                 }
4667
4668                 return $this->conn;
4669         }
4670
4671         /**
4672          * @since 1.19
4673          * @return string
4674          */
4675         public function __toString() {
4676                 return (string)$this->conn;
4677         }
4678
4679         /**
4680          * Make sure that copies do not share the same client binding handle
4681          * @throws DBConnectionError
4682          */
4683         public function __clone() {
4684                 $this->connLogger->warning(
4685                         "Cloning " . static::class . " is not recommended; forking connection:\n" .
4686                         ( new RuntimeException() )->getTraceAsString()
4687                 );
4688
4689                 if ( $this->isOpen() ) {
4690                         // Open a new connection resource without messing with the old one
4691                         $this->opened = false;
4692                         $this->conn = false;
4693                         $this->trxEndCallbacks = []; // don't copy
4694                         $this->handleSessionLoss(); // no trx or locks anymore
4695                         $this->open(
4696                                 $this->server,
4697                                 $this->user,
4698                                 $this->password,
4699                                 $this->getDBname(),
4700                                 $this->dbSchema(),
4701                                 $this->tablePrefix()
4702                         );
4703                         $this->lastPing = microtime( true );
4704                 }
4705         }
4706
4707         /**
4708          * Called by serialize. Throw an exception when DB connection is serialized.
4709          * This causes problems on some database engines because the connection is
4710          * not restored on unserialize.
4711          */
4712         public function __sleep() {
4713                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
4714                         'the connection is not restored on wakeup.' );
4715         }
4716
4717         /**
4718          * Run a few simple sanity checks and close dangling connections
4719          */
4720         public function __destruct() {
4721                 if ( $this->trxLevel && $this->trxDoneWrites ) {
4722                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
4723                 }
4724
4725                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
4726                 if ( $danglingWriters ) {
4727                         $fnames = implode( ', ', $danglingWriters );
4728                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
4729                 }
4730
4731                 if ( $this->conn ) {
4732                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
4733                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
4734                         Wikimedia\suppressWarnings();
4735                         $this->closeConnection();
4736                         Wikimedia\restoreWarnings();
4737                         $this->conn = false;
4738                         $this->opened = false;
4739                 }
4740         }
4741 }
4742
4743 /**
4744  * @deprecated since 1.28
4745  */
4746 class_alias( Database::class, 'DatabaseBase' );
4747
4748 /**
4749  * @deprecated since 1.29
4750  */
4751 class_alias( Database::class, 'Database' );