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 InvalidArgumentException;
  37 use Exception;
  38 use RuntimeException;
  39
  40 /**
  41  * Relational database abstraction object
  42  *
  43  * @ingroup Database
  44  * @since 1.28
  45  */
  46 abstract class Database implements IDatabase, IMaintainableDatabase, LoggerAwareInterface {
  47         /** Number of times to re-try an operation in case of deadlock */
  48         const DEADLOCK_TRIES = 4;
  49         /** Minimum time to wait before retry, in microseconds */
  50         const DEADLOCK_DELAY_MIN = 500000;
  51         /** Maximum time to wait before retry */
  52         const DEADLOCK_DELAY_MAX = 1500000;
  53
  54         /** How long before it is worth doing a dummy query to test the connection */
  55         const PING_TTL = 1.0;
  56         const PING_QUERY = 'SELECT 1 AS ping';
  57
  58         const TINY_WRITE_SEC = 0.010;
  59         const SLOW_WRITE_SEC = 0.500;
  60         const SMALL_WRITE_ROWS = 100;
  61
  62         /** @var string SQL query */
  63         protected $lastQuery = '';
  64         /** @var float|bool UNIX timestamp of last write query */
  65         protected $lastWriteTime = false;
  66         /** @var string|bool */
  67         protected $phpError = false;
  68         /** @var string */
  69         protected $server;
  70         /** @var string */
  71         protected $user;
  72         /** @var string */
  73         protected $password;
  74         /** @var string */
  75         protected $dbName;
  76         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  77         protected $tableAliases = [];
  78         /** @var bool Whether this PHP instance is for a CLI script */
  79         protected $cliMode;
  80         /** @var string Agent name for query profiling */
  81         protected $agent;
  82
  83         /** @var BagOStuff APC cache */
  84         protected $srvCache;
  85         /** @var LoggerInterface */
  86         protected $connLogger;
  87         /** @var LoggerInterface */
  88         protected $queryLogger;
  89         /** @var callback Error logging callback */
  90         protected $errorLogger;
  91
  92         /** @var resource|null Database connection */
  93         protected $conn = null;
  94         /** @var bool */
  95         protected $opened = false;
  96
  97         /** @var array[] List of (callable, method name) */
  98         protected $trxIdleCallbacks = [];
  99         /** @var array[] List of (callable, method name) */
 100         protected $trxPreCommitCallbacks = [];
 101         /** @var array[] List of (callable, method name) */
 102         protected $trxEndCallbacks = [];
 103         /** @var callable[] Map of (name => callable) */
 104         protected $trxRecurringCallbacks = [];
 105         /** @var bool Whether to suppress triggering of transaction end callbacks */
 106         protected $trxEndCallbacksSuppressed = false;
 107
 108         /** @var string */
 109         protected $tablePrefix = '';
 110         /** @var string */
 111         protected $schema = '';
 112         /** @var int */
 113         protected $flags;
 114         /** @var array */
 115         protected $lbInfo = [];
 116         /** @var array|bool */
 117         protected $schemaVars = false;
 118         /** @var array */
 119         protected $sessionVars = [];
 120         /** @var array|null */
 121         protected $preparedArgs;
 122         /** @var string|bool|null Stashed value of html_errors INI setting */
 123         protected $htmlErrors;
 124         /** @var string */
 125         protected $delimiter = ';';
 126         /** @var DatabaseDomain */
 127         protected $currentDomain;
 128         /** @var integer|null Rows affected by the last query to query() or its CRUD wrappers */
 129         protected $affectedRowCount;
 130
 131         /**
 132          * Either 1 if a transaction is active or 0 otherwise.
 133          * The other Trx fields may not be meaningfull if this is 0.
 134          *
 135          * @var int
 136          */
 137         protected $trxLevel = 0;
 138         /**
 139          * Either a short hexidecimal string if a transaction is active or ""
 140          *
 141          * @var string
 142          * @see Database::trxLevel
 143          */
 144         protected $trxShortId = '';
 145         /**
 146          * The UNIX time that the transaction started. Callers can assume that if
 147          * snapshot isolation is used, then the data is *at least* up to date to that
 148          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 149          *
 150          * @var float|null
 151          * @see Database::trxLevel
 152          */
 153         private $trxTimestamp = null;
 154         /** @var float Lag estimate at the time of BEGIN */
 155         private $trxReplicaLag = null;
 156         /**
 157          * Remembers the function name given for starting the most recent transaction via begin().
 158          * Used to provide additional context for error reporting.
 159          *
 160          * @var string
 161          * @see Database::trxLevel
 162          */
 163         private $trxFname = null;
 164         /**
 165          * Record if possible write queries were done in the last transaction started
 166          *
 167          * @var bool
 168          * @see Database::trxLevel
 169          */
 170         private $trxDoneWrites = false;
 171         /**
 172          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 173          *
 174          * @var bool
 175          * @see Database::trxLevel
 176          */
 177         private $trxAutomatic = false;
 178         /**
 179          * Array of levels of atomicity within transactions
 180          *
 181          * @var array
 182          */
 183         private $trxAtomicLevels = [];
 184         /**
 185          * Record if the current transaction was started implicitly by Database::startAtomic
 186          *
 187          * @var bool
 188          */
 189         private $trxAutomaticAtomic = false;
 190         /**
 191          * Track the write query callers of the current transaction
 192          *
 193          * @var string[]
 194          */
 195         private $trxWriteCallers = [];
 196         /**
 197          * @var float Seconds spent in write queries for the current transaction
 198          */
 199         private $trxWriteDuration = 0.0;
 200         /**
 201          * @var int Number of write queries for the current transaction
 202          */
 203         private $trxWriteQueryCount = 0;
 204         /**
 205          * @var int Number of rows affected by write queries for the current transaction
 206          */
 207         private $trxWriteAffectedRows = 0;
 208         /**
 209          * @var float Like trxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 210          */
 211         private $trxWriteAdjDuration = 0.0;
 212         /**
 213          * @var int Number of write queries counted in trxWriteAdjDuration
 214          */
 215         private $trxWriteAdjQueryCount = 0;
 216         /**
 217          * @var float RTT time estimate
 218          */
 219         private $rttEstimate = 0.0;
 220
 221         /** @var array Map of (name => 1) for locks obtained via lock() */
 222         private $namedLocksHeld = [];
 223         /** @var array Map of (table name => 1) for TEMPORARY tables */
 224         protected $sessionTempTables = [];
 225
 226         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 227         private $lazyMasterHandle;
 228
 229         /** @var float UNIX timestamp */
 230         protected $lastPing = 0.0;
 231
 232         /** @var int[] Prior flags member variable values */
 233         private $priorFlags = [];
 234
 235         /** @var object|string Class name or object With profileIn/profileOut methods */
 236         protected $profiler;
 237         /** @var TransactionProfiler */
 238         protected $trxProfiler;
 239
 240         /** @var int */
 241         protected $nonNativeInsertSelectBatchSize = 10000;
 242
 243         /**
 244          * Constructor and database handle and attempt to connect to the DB server
 245          *
 246          * IDatabase classes should not be constructed directly in external
 247          * code. Database::factory() should be used instead.
 248          *
 249          * @param array $params Parameters passed from Database::factory()
 250          */
 251         function __construct( array $params ) {
 252                 $server = $params['host'];
 253                 $user = $params['user'];
 254                 $password = $params['password'];
 255                 $dbName = $params['dbname'];
 256
 257                 $this->schema = $params['schema'];
 258                 $this->tablePrefix = $params['tablePrefix'];
 259
 260                 $this->cliMode = $params['cliMode'];
 261                 // Agent name is added to SQL queries in a comment, so make sure it can't break out
 262                 $this->agent = str_replace( '/', '-', $params['agent'] );
 263
 264                 $this->flags = $params['flags'];
 265                 if ( $this->flags & self::DBO_DEFAULT ) {
 266                         if ( $this->cliMode ) {
 267                                 $this->flags &= ~self::DBO_TRX;
 268                         } else {
 269                                 $this->flags |= self::DBO_TRX;
 270                         }
 271                 }
 272
 273                 $this->sessionVars = $params['variables'];
 274
 275                 $this->srvCache = isset( $params['srvCache'] )
 276                         ? $params['srvCache']
 277                         : new HashBagOStuff();
 278
 279                 $this->profiler = $params['profiler'];
 280                 $this->trxProfiler = $params['trxProfiler'];
 281                 $this->connLogger = $params['connLogger'];
 282                 $this->queryLogger = $params['queryLogger'];
 283                 $this->errorLogger = $params['errorLogger'];
 284
 285                 if ( isset( $params['nonNativeInsertSelectBatchSize'] ) ) {
 286                         $this->nonNativeInsertSelectBatchSize = $params['nonNativeInsertSelectBatchSize'];
 287                 }
 288
 289                 // Set initial dummy domain until open() sets the final DB/prefix
 290                 $this->currentDomain = DatabaseDomain::newUnspecified();
 291
 292                 if ( $user ) {
 293                         $this->open( $server, $user, $password, $dbName );
 294                 } elseif ( $this->requiresDatabaseUser() ) {
 295                         throw new InvalidArgumentException( "No database user provided." );
 296                 }
 297
 298                 // Set the domain object after open() sets the relevant fields
 299                 if ( $this->dbName != '' ) {
 300                         // Domains with server scope but a table prefix are not used by IDatabase classes
 301                         $this->currentDomain = new DatabaseDomain( $this->dbName, null, $this->tablePrefix );
 302                 }
 303         }
 304
 305         /**
 306          * Construct a Database subclass instance given a database type and parameters
 307          *
 308          * This also connects to the database immediately upon object construction
 309          *
 310          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 311          * @param array $p Parameter map with keys:
 312          *   - host : The hostname of the DB server
 313          *   - user : The name of the database user the client operates under
 314          *   - password : The password for the database user
 315          *   - dbname : The name of the database to use where queries do not specify one.
 316          *      The database must exist or an error might be thrown. Setting this to the empty string
 317          *      will avoid any such errors and make the handle have no implicit database scope. This is
 318          *      useful for queries like SHOW STATUS, CREATE DATABASE, or DROP DATABASE. Note that a
 319          *      "database" in Postgres is rougly equivalent to an entire MySQL server. This the domain
 320          *      in which user names and such are defined, e.g. users are database-specific in Postgres.
 321          *   - schema : The database schema to use (if supported). A "schema" in Postgres is roughly
 322          *      equivalent to a "database" in MySQL. Note that MySQL and SQLite do not use schemas.
 323          *   - tablePrefix : Optional table prefix that is implicitly added on to all table names
 324          *      recognized in queries. This can be used in place of schemas for handle site farms.
 325          *   - flags : Optional bitfield of DBO_* constants that define connection, protocol,
 326          *      buffering, and transaction behavior. It is STRONGLY adviced to leave the DBO_DEFAULT
 327          *      flag in place UNLESS this this database simply acts as a key/value store.
 328          *   - driver: Optional name of a specific DB client driver. For MySQL, there is only the
 329          *      'mysqli' driver; the old one 'mysql' has been removed.
 330          *   - variables: Optional map of session variables to set after connecting. This can be
 331          *      used to adjust lock timeouts or encoding modes and the like.
 332          *   - connLogger: Optional PSR-3 logger interface instance.
 333          *   - queryLogger: Optional PSR-3 logger interface instance.
 334          *   - profiler: Optional class name or object with profileIn()/profileOut() methods.
 335          *      These will be called in query(), using a simplified version of the SQL that also
 336          *      includes the agent as a SQL comment.
 337          *   - trxProfiler: Optional TransactionProfiler instance.
 338          *   - errorLogger: Optional callback that takes an Exception and logs it.
 339          *   - cliMode: Whether to consider the execution context that of a CLI script.
 340          *   - agent: Optional name used to identify the end-user in query profiling/logging.
 341          *   - srvCache: Optional BagOStuff instance to an APC-style cache.
 342          *   - nonNativeInsertSelectBatchSize: Optional batch size for non-native INSERT SELECT emulation.
 343          * @return Database|null If the database driver or extension cannot be found
 344          * @throws InvalidArgumentException If the database driver or extension cannot be found
 345          * @since 1.18
 346          */
 347         final public static function factory( $dbType, $p = [] ) {
 348                 $class = self::getClass( $dbType, isset( $p['driver'] ) ? $p['driver'] : null );
 349
 350                 if ( class_exists( $class ) && is_subclass_of( $class, IDatabase::class ) ) {
 351                         // Resolve some defaults for b/c
 352                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 353                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 354                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 355                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 356                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 357                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 358                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 359                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : '';
 360                         $p['cliMode'] = isset( $p['cliMode'] )
 361                                 ? $p['cliMode']
 362                                 : ( PHP_SAPI === 'cli' || PHP_SAPI === 'phpdbg' );
 363                         $p['agent'] = isset( $p['agent'] ) ? $p['agent'] : '';
 364                         if ( !isset( $p['connLogger'] ) ) {
 365                                 $p['connLogger'] = new NullLogger();
 366                         }
 367                         if ( !isset( $p['queryLogger'] ) ) {
 368                                 $p['queryLogger'] = new NullLogger();
 369                         }
 370                         $p['profiler'] = isset( $p['profiler'] ) ? $p['profiler'] : null;
 371                         if ( !isset( $p['trxProfiler'] ) ) {
 372                                 $p['trxProfiler'] = new TransactionProfiler();
 373                         }
 374                         if ( !isset( $p['errorLogger'] ) ) {
 375                                 $p['errorLogger'] = function ( Exception $e ) {
 376                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_USER_WARNING );
 377                                 };
 378                         }
 379
 380                         $conn = new $class( $p );
 381                 } else {
 382                         $conn = null;
 383                 }
 384
 385                 return $conn;
 386         }
 387
 388         /**
 389          * @param string $dbType A possible DB type (sqlite, mysql, postgres,...)
 390          * @param string|null $driver Optional name of a specific DB client driver
 391          * @return string Database subclass name to use
 392          * @throws InvalidArgumentException
 393          */
 394         private static function getClass( $dbType, $driver = null ) {
 395                 // For database types with built-in support, the below maps type to IDatabase
 396                 // implementations. For types with multipe driver implementations (PHP extensions),
 397                 // an array can be used, keyed by extension name. In case of an array, the
 398                 // optional 'driver' parameter can be used to force a specific driver. Otherwise,
 399                 // we auto-detect the first available driver. For types without built-in support,
 400                 // an class named "Database<Type>" us used, eg. DatabaseFoo for type 'foo'.
 401                 static $builtinTypes = [
 402                         'mssql' => DatabaseMssql::class,
 403                         'mysql' => [ 'mysqli' => DatabaseMysqli::class ],
 404                         'sqlite' => DatabaseSqlite::class,
 405                         'postgres' => DatabasePostgres::class,
 406                 ];
 407
 408                 $dbType = strtolower( $dbType );
 409                 $class = false;
 410
 411                 if ( isset( $builtinTypes[$dbType] ) ) {
 412                         $possibleDrivers = $builtinTypes[$dbType];
 413                         if ( is_string( $possibleDrivers ) ) {
 414                                 $class = $possibleDrivers;
 415                         } else {
 416                                 if ( (string)$driver !== '' ) {
 417                                         if ( !isset( $possibleDrivers[$driver] ) ) {
 418                                                 throw new InvalidArgumentException( __METHOD__ .
 419                                                         " type '$dbType' does not support driver '{$driver}'" );
 420                                         } else {
 421                                                 $class = $possibleDrivers[$driver];
 422                                         }
 423                                 } else {
 424                                         foreach ( $possibleDrivers as $posDriver => $possibleClass ) {
 425                                                 if ( extension_loaded( $posDriver ) ) {
 426                                                         $class = $possibleClass;
 427                                                         break;
 428                                                 }
 429                                         }
 430                                 }
 431                         }
 432                 } else {
 433                         $class = 'Database' . ucfirst( $dbType );
 434                 }
 435
 436                 if ( $class === false ) {
 437                         throw new InvalidArgumentException( __METHOD__ .
 438                                 " no viable database extension found for type '$dbType'" );
 439                 }
 440
 441                 return $class;
 442         }
 443
 444         /**
 445          * Set the PSR-3 logger interface to use for query logging. (The logger
 446          * interfaces for connection logging and error logging can be set with the
 447          * constructor.)
 448          *
 449          * @param LoggerInterface $logger
 450          */
 451         public function setLogger( LoggerInterface $logger ) {
 452                 $this->queryLogger = $logger;
 453         }
 454
 455         public function getServerInfo() {
 456                 return $this->getServerVersion();
 457         }
 458
 459         public function bufferResults( $buffer = null ) {
 460                 $res = !$this->getFlag( self::DBO_NOBUFFER );
 461                 if ( $buffer !== null ) {
 462                         $buffer
 463                                 ? $this->clearFlag( self::DBO_NOBUFFER )
 464                                 : $this->setFlag( self::DBO_NOBUFFER );
 465                 }
 466
 467                 return $res;
 468         }
 469
 470         /**
 471          * Turns on (false) or off (true) the automatic generation and sending
 472          * of a "we're sorry, but there has been a database error" page on
 473          * database errors. Default is on (false). When turned off, the
 474          * code should use lastErrno() and lastError() to handle the
 475          * situation as appropriate.
 476          *
 477          * Do not use this function outside of the Database classes.
 478          *
 479          * @param null|bool $ignoreErrors
 480          * @return bool The previous value of the flag.
 481          */
 482         protected function ignoreErrors( $ignoreErrors = null ) {
 483                 $res = $this->getFlag( self::DBO_IGNORE );
 484                 if ( $ignoreErrors !== null ) {
 485                         // setFlag()/clearFlag() do not allow DBO_IGNORE changes for sanity
 486                         if ( $ignoreErrors ) {
 487                                 $this->flags |= self::DBO_IGNORE;
 488                         } else {
 489                                 $this->flags &= ~self::DBO_IGNORE;
 490                         }
 491                 }
 492
 493                 return $res;
 494         }
 495
 496         public function trxLevel() {
 497                 return $this->trxLevel;
 498         }
 499
 500         public function trxTimestamp() {
 501                 return $this->trxLevel ? $this->trxTimestamp : null;
 502         }
 503
 504         public function tablePrefix( $prefix = null ) {
 505                 $old = $this->tablePrefix;
 506                 if ( $prefix !== null ) {
 507                         $this->tablePrefix = $prefix;
 508                         $this->currentDomain = ( $this->dbName != '' )
 509                                 ? new DatabaseDomain( $this->dbName, null, $this->tablePrefix )
 510                                 : DatabaseDomain::newUnspecified();
 511                 }
 512
 513                 return $old;
 514         }
 515
 516         public function dbSchema( $schema = null ) {
 517                 $old = $this->schema;
 518                 if ( $schema !== null ) {
 519                         $this->schema = $schema;
 520                 }
 521
 522                 return $old;
 523         }
 524
 525         public function getLBInfo( $name = null ) {
 526                 if ( is_null( $name ) ) {
 527                         return $this->lbInfo;
 528                 } else {
 529                         if ( array_key_exists( $name, $this->lbInfo ) ) {
 530                                 return $this->lbInfo[$name];
 531                         } else {
 532                                 return null;
 533                         }
 534                 }
 535         }
 536
 537         public function setLBInfo( $name, $value = null ) {
 538                 if ( is_null( $value ) ) {
 539                         $this->lbInfo = $name;
 540                 } else {
 541                         $this->lbInfo[$name] = $value;
 542                 }
 543         }
 544
 545         public function setLazyMasterHandle( IDatabase $conn ) {
 546                 $this->lazyMasterHandle = $conn;
 547         }
 548
 549         /**
 550          * @return IDatabase|null
 551          * @see setLazyMasterHandle()
 552          * @since 1.27
 553          */
 554         protected function getLazyMasterHandle() {
 555                 return $this->lazyMasterHandle;
 556         }
 557
 558         public function implicitGroupby() {
 559                 return true;
 560         }
 561
 562         public function implicitOrderby() {
 563                 return true;
 564         }
 565
 566         public function lastQuery() {
 567                 return $this->lastQuery;
 568         }
 569
 570         public function doneWrites() {
 571                 return (bool)$this->lastWriteTime;
 572         }
 573
 574         public function lastDoneWrites() {
 575                 return $this->lastWriteTime ?: false;
 576         }
 577
 578         public function writesPending() {
 579                 return $this->trxLevel && $this->trxDoneWrites;
 580         }
 581
 582         public function writesOrCallbacksPending() {
 583                 return $this->trxLevel && (
 584                         $this->trxDoneWrites || $this->trxIdleCallbacks || $this->trxPreCommitCallbacks
 585                 );
 586         }
 587
 588         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 589                 if ( !$this->trxLevel ) {
 590                         return false;
 591                 } elseif ( !$this->trxDoneWrites ) {
 592                         return 0.0;
 593                 }
 594
 595                 switch ( $type ) {
 596                         case self::ESTIMATE_DB_APPLY:
 597                                 $this->ping( $rtt );
 598                                 $rttAdjTotal = $this->trxWriteAdjQueryCount * $rtt;
 599                                 $applyTime = max( $this->trxWriteAdjDuration - $rttAdjTotal, 0 );
 600                                 // For omitted queries, make them count as something at least
 601                                 $omitted = $this->trxWriteQueryCount - $this->trxWriteAdjQueryCount;
 602                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 603
 604                                 return $applyTime;
 605                         default: // everything
 606                                 return $this->trxWriteDuration;
 607                 }
 608         }
 609
 610         public function pendingWriteCallers() {
 611                 return $this->trxLevel ? $this->trxWriteCallers : [];
 612         }
 613
 614         public function pendingWriteRowsAffected() {
 615                 return $this->trxWriteAffectedRows;
 616         }
 617
 618         /**
 619          * Get the list of method names that have pending write queries or callbacks
 620          * for this transaction
 621          *
 622          * @return array
 623          */
 624         protected function pendingWriteAndCallbackCallers() {
 625                 if ( !$this->trxLevel ) {
 626                         return [];
 627                 }
 628
 629                 $fnames = $this->trxWriteCallers;
 630                 foreach ( [
 631                         $this->trxIdleCallbacks,
 632                         $this->trxPreCommitCallbacks,
 633                         $this->trxEndCallbacks
 634                 ] as $callbacks ) {
 635                         foreach ( $callbacks as $callback ) {
 636                                 $fnames[] = $callback[1];
 637                         }
 638                 }
 639
 640                 return $fnames;
 641         }
 642
 643         public function isOpen() {
 644                 return $this->opened;
 645         }
 646
 647         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 648                 if ( ( $flag & self::DBO_IGNORE ) ) {
 649                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 650                 }
 651
 652                 if ( $remember === self::REMEMBER_PRIOR ) {
 653                         array_push( $this->priorFlags, $this->flags );
 654                 }
 655                 $this->flags |= $flag;
 656         }
 657
 658         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 659                 if ( ( $flag & self::DBO_IGNORE ) ) {
 660                         throw new \UnexpectedValueException( "Modifying DBO_IGNORE is not allowed." );
 661                 }
 662
 663                 if ( $remember === self::REMEMBER_PRIOR ) {
 664                         array_push( $this->priorFlags, $this->flags );
 665                 }
 666                 $this->flags &= ~$flag;
 667         }
 668
 669         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 670                 if ( !$this->priorFlags ) {
 671                         return;
 672                 }
 673
 674                 if ( $state === self::RESTORE_INITIAL ) {
 675                         $this->flags = reset( $this->priorFlags );
 676                         $this->priorFlags = [];
 677                 } else {
 678                         $this->flags = array_pop( $this->priorFlags );
 679                 }
 680         }
 681
 682         public function getFlag( $flag ) {
 683                 return !!( $this->flags & $flag );
 684         }
 685
 686         /**
 687          * @param string $name Class field name
 688          * @return mixed
 689          * @deprecated Since 1.28
 690          */
 691         public function getProperty( $name ) {
 692                 return $this->$name;
 693         }
 694
 695         public function getDomainID() {
 696                 return $this->currentDomain->getId();
 697         }
 698
 699         final public function getWikiID() {
 700                 return $this->getDomainID();
 701         }
 702
 703         /**
 704          * Get information about an index into an object
 705          * @param string $table Table name
 706          * @param string $index Index name
 707          * @param string $fname Calling function name
 708          * @return mixed Database-specific index description class or false if the index does not exist
 709          */
 710         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 711
 712         /**
 713          * Wrapper for addslashes()
 714          *
 715          * @param string $s String to be slashed.
 716          * @return string Slashed string.
 717          */
 718         abstract function strencode( $s );
 719
 720         /**
 721          * Set a custom error handler for logging errors during database connection
 722          */
 723         protected function installErrorHandler() {
 724                 $this->phpError = false;
 725                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 726                 set_error_handler( [ $this, 'connectionErrorLogger' ] );
 727         }
 728
 729         /**
 730          * Restore the previous error handler and return the last PHP error for this DB
 731          *
 732          * @return bool|string
 733          */
 734         protected function restoreErrorHandler() {
 735                 restore_error_handler();
 736                 if ( $this->htmlErrors !== false ) {
 737                         ini_set( 'html_errors', $this->htmlErrors );
 738                 }
 739
 740                 return $this->getLastPHPError();
 741         }
 742
 743         /**
 744          * @return string|bool Last PHP error for this DB (typically connection errors)
 745          */
 746         protected function getLastPHPError() {
 747                 if ( $this->phpError ) {
 748                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->phpError );
 749                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 750
 751                         return $error;
 752                 }
 753
 754                 return false;
 755         }
 756
 757         /**
 758          * Error handler for logging errors during database connection
 759          * This method should not be used outside of Database classes
 760          *
 761          * @param int $errno
 762          * @param string $errstr
 763          */
 764         public function connectionErrorLogger( $errno, $errstr ) {
 765                 $this->phpError = $errstr;
 766         }
 767
 768         /**
 769          * Create a log context to pass to PSR-3 logger functions.
 770          *
 771          * @param array $extras Additional data to add to context
 772          * @return array
 773          */
 774         protected function getLogContext( array $extras = [] ) {
 775                 return array_merge(
 776                         [
 777                                 'db_server' => $this->server,
 778                                 'db_name' => $this->dbName,
 779                                 'db_user' => $this->user,
 780                         ],
 781                         $extras
 782                 );
 783         }
 784
 785         public function close() {
 786                 if ( $this->conn ) {
 787                         if ( $this->trxLevel() ) {
 788                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 789                         }
 790
 791                         $closed = $this->closeConnection();
 792                         $this->conn = false;
 793                 } elseif (
 794                         $this->trxIdleCallbacks ||
 795                         $this->trxPreCommitCallbacks ||
 796                         $this->trxEndCallbacks
 797                 ) { // sanity
 798                         throw new RuntimeException( "Transaction callbacks still pending." );
 799                 } else {
 800                         $closed = true;
 801                 }
 802                 $this->opened = false;
 803
 804                 return $closed;
 805         }
 806
 807         /**
 808          * Make sure isOpen() returns true as a sanity check
 809          *
 810          * @throws DBUnexpectedError
 811          */
 812         protected function assertOpen() {
 813                 if ( !$this->isOpen() ) {
 814                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 815                 }
 816         }
 817
 818         /**
 819          * Closes underlying database connection
 820          * @since 1.20
 821          * @return bool Whether connection was closed successfully
 822          */
 823         abstract protected function closeConnection();
 824
 825         public function reportConnectionError( $error = 'Unknown error' ) {
 826                 $myError = $this->lastError();
 827                 if ( $myError ) {
 828                         $error = $myError;
 829                 }
 830
 831                 # New method
 832                 throw new DBConnectionError( $this, $error );
 833         }
 834
 835         /**
 836          * The DBMS-dependent part of query()
 837          *
 838          * @param string $sql SQL query.
 839          * @return ResultWrapper|bool Result object to feed to fetchObject,
 840          *   fetchRow, ...; or false on failure
 841          */
 842         abstract protected function doQuery( $sql );
 843
 844         /**
 845          * Determine whether a query writes to the DB.
 846          * Should return true if unsure.
 847          *
 848          * @param string $sql
 849          * @return bool
 850          */
 851         protected function isWriteQuery( $sql ) {
 852                 return !preg_match(
 853                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 854         }
 855
 856         /**
 857          * @param string $sql
 858          * @return string|null
 859          */
 860         protected function getQueryVerb( $sql ) {
 861                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 862         }
 863
 864         /**
 865          * Determine whether a SQL statement is sensitive to isolation level.
 866          * A SQL statement is considered transactable if its result could vary
 867          * depending on the transaction isolation level. Operational commands
 868          * such as 'SET' and 'SHOW' are not considered to be transactable.
 869          *
 870          * @param string $sql
 871          * @return bool
 872          */
 873         protected function isTransactableQuery( $sql ) {
 874                 return !in_array(
 875                         $this->getQueryVerb( $sql ),
 876                         [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET', 'CREATE', 'ALTER' ],
 877                         true
 878                 );
 879         }
 880
 881         /**
 882          * @param string $sql A SQL query
 883          * @return bool Whether $sql is SQL for TEMPORARY table operation
 884          */
 885         protected function registerTempTableOperation( $sql ) {
 886                 if ( preg_match(
 887                         '/^CREATE\s+TEMPORARY\s+TABLE\s+(?:IF\s+NOT\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 888                         $sql,
 889                         $matches
 890                 ) ) {
 891                         $this->sessionTempTables[$matches[1]] = 1;
 892
 893                         return true;
 894                 } elseif ( preg_match(
 895                         '/^DROP\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 896                         $sql,
 897                         $matches
 898                 ) ) {
 899                         $isTemp = isset( $this->sessionTempTables[$matches[1]] );
 900                         unset( $this->sessionTempTables[$matches[1]] );
 901
 902                         return $isTemp;
 903                 } elseif ( preg_match(
 904                         '/^TRUNCATE\s+(?:TEMPORARY\s+)?TABLE\s+(?:IF\s+EXISTS\s+)?[`"\']?(\w+)[`"\']?/i',
 905                         $sql,
 906                         $matches
 907                 ) ) {
 908                         return isset( $this->sessionTempTables[$matches[1]] );
 909                 } elseif ( preg_match(
 910                         '/^(?:INSERT\s+(?:\w+\s+)?INTO|UPDATE|DELETE\s+FROM)\s+[`"\']?(\w+)[`"\']?/i',
 911                         $sql,
 912                         $matches
 913                 ) ) {
 914                         return isset( $this->sessionTempTables[$matches[1]] );
 915                 }
 916
 917                 return false;
 918         }
 919
 920         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 921                 $priorWritesPending = $this->writesOrCallbacksPending();
 922                 $this->lastQuery = $sql;
 923
 924                 $isWrite = $this->isWriteQuery( $sql );
 925                 if ( $isWrite ) {
 926                         $isNonTempWrite = !$this->registerTempTableOperation( $sql );
 927                 } else {
 928                         $isNonTempWrite = false;
 929                 }
 930
 931                 if ( $isWrite ) {
 932                         if ( $this->getLBInfo( 'replica' ) === true ) {
 933                                 throw new DBError(
 934                                         $this,
 935                                         'Write operations are not allowed on replica database connections.'
 936                                 );
 937                         }
 938                         # In theory, non-persistent writes are allowed in read-only mode, but due to things
 939                         # like https://bugs.mysql.com/bug.php?id=33669 that might not work anyway...
 940                         $reason = $this->getReadOnlyReason();
 941                         if ( $reason !== false ) {
 942                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 943                         }
 944                         # Set a flag indicating that writes have been done
 945                         $this->lastWriteTime = microtime( true );
 946                 }
 947
 948                 # Add trace comment to the begin of the sql string, right after the operator.
 949                 # Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (T44598)
 950                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 951
 952                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 953                 if ( !$this->trxLevel && $this->getFlag( self::DBO_TRX )
 954                         && $this->isTransactableQuery( $sql )
 955                 ) {
 956                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 957                         $this->trxAutomatic = true;
 958                 }
 959
 960                 # Keep track of whether the transaction has write queries pending
 961                 if ( $this->trxLevel && !$this->trxDoneWrites && $isWrite ) {
 962                         $this->trxDoneWrites = true;
 963                         $this->trxProfiler->transactionWritingIn(
 964                                 $this->server, $this->dbName, $this->trxShortId );
 965                 }
 966
 967                 if ( $this->getFlag( self::DBO_DEBUG ) ) {
 968                         $this->queryLogger->debug( "{$this->dbName} {$commentedSql}" );
 969                 }
 970
 971                 # Avoid fatals if close() was called
 972                 $this->assertOpen();
 973
 974                 # Send the query to the server
 975                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 976
 977                 # Try reconnecting if the connection was lost
 978                 if ( false === $ret && $this->wasErrorReissuable() ) {
 979                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 980                         # Stash the last error values before anything might clear them
 981                         $lastError = $this->lastError();
 982                         $lastErrno = $this->lastErrno();
 983                         # Update state tracking to reflect transaction loss due to disconnection
 984                         $this->handleSessionLoss();
 985                         if ( $this->reconnect() ) {
 986                                 $msg = __METHOD__ . ': lost connection to {dbserver}; reconnected';
 987                                 $params = [ 'dbserver' => $this->getServer() ];
 988                                 $this->connLogger->warning( $msg, $params );
 989                                 $this->queryLogger->warning( $msg, $params +
 990                                         [ 'trace' => ( new RuntimeException() )->getTraceAsString() ] );
 991
 992                                 if ( !$recoverable ) {
 993                                         # Callers may catch the exception and continue to use the DB
 994                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 995                                 } else {
 996                                         # Should be safe to silently retry the query
 997                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isNonTempWrite, $fname );
 998                                 }
 999                         } else {
1000                                 $msg = __METHOD__ . ': lost connection to {dbserver} permanently';
1001                                 $this->connLogger->error( $msg, [ 'dbserver' => $this->getServer() ] );
1002                         }
1003                 }
1004
1005                 if ( false === $ret ) {
1006                         # Deadlocks cause the entire transaction to abort, not just the statement.
1007                         # https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1008                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
1009                         if ( $this->wasDeadlock() ) {
1010                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
1011                                         $tempIgnore = false; // not recoverable
1012                                 }
1013                                 # Update state tracking to reflect transaction loss
1014                                 $this->handleSessionLoss();
1015                         }
1016
1017                         $this->reportQueryError(
1018                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1019                 }
1020
1021                 $res = $this->resultObject( $ret );
1022
1023                 return $res;
1024         }
1025
1026         /**
1027          * Wrapper for query() that also handles profiling, logging, and affected row count updates
1028          *
1029          * @param string $sql Original SQL query
1030          * @param string $commentedSql SQL query with debugging/trace comment
1031          * @param bool $isWrite Whether the query is a (non-temporary) write operation
1032          * @param string $fname Name of the calling function
1033          * @return bool|ResultWrapper True for a successful write query, ResultWrapper
1034          *     object for a successful read query, or false on failure
1035          */
1036         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
1037                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1038                 # generalizeSQL() will probably cut down the query to reasonable
1039                 # logging size most of the time. The substr is really just a sanity check.
1040                 if ( $isMaster ) {
1041                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1042                 } else {
1043                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
1044                 }
1045
1046                 # Include query transaction state
1047                 $queryProf .= $this->trxShortId ? " [TRX#{$this->trxShortId}]" : "";
1048
1049                 $startTime = microtime( true );
1050                 if ( $this->profiler ) {
1051                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
1052                 }
1053                 $this->affectedRowCount = null;
1054                 $ret = $this->doQuery( $commentedSql );
1055                 $this->affectedRowCount = $this->affectedRows();
1056                 if ( $this->profiler ) {
1057                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
1058                 }
1059                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
1060
1061                 unset( $queryProfSection ); // profile out (if set)
1062
1063                 if ( $ret !== false ) {
1064                         $this->lastPing = $startTime;
1065                         if ( $isWrite && $this->trxLevel ) {
1066                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime, $this->affectedRows() );
1067                                 $this->trxWriteCallers[] = $fname;
1068                         }
1069                 }
1070
1071                 if ( $sql === self::PING_QUERY ) {
1072                         $this->rttEstimate = $queryRuntime;
1073                 }
1074
1075                 $this->trxProfiler->recordQueryCompletion(
1076                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1077                 );
1078                 $this->queryLogger->debug( $sql, [
1079                         'method' => $fname,
1080                         'master' => $isMaster,
1081                         'runtime' => $queryRuntime,
1082                 ] );
1083
1084                 return $ret;
1085         }
1086
1087         /**
1088          * Update the estimated run-time of a query, not counting large row lock times
1089          *
1090          * LoadBalancer can be set to rollback transactions that will create huge replication
1091          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1092          * queries, like inserting a row can take a long time due to row locking. This method
1093          * uses some simple heuristics to discount those cases.
1094          *
1095          * @param string $sql A SQL write query
1096          * @param float $runtime Total runtime, including RTT
1097          * @param int $affected Affected row count
1098          */
1099         private function updateTrxWriteQueryTime( $sql, $runtime, $affected ) {
1100                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1101                 $indicativeOfReplicaRuntime = true;
1102                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1103                         $verb = $this->getQueryVerb( $sql );
1104                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1105                         if ( $verb === 'INSERT' ) {
1106                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1107                         } elseif ( $verb === 'REPLACE' ) {
1108                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1109                         }
1110                 }
1111
1112                 $this->trxWriteDuration += $runtime;
1113                 $this->trxWriteQueryCount += 1;
1114                 $this->trxWriteAffectedRows += $affected;
1115                 if ( $indicativeOfReplicaRuntime ) {
1116                         $this->trxWriteAdjDuration += $runtime;
1117                         $this->trxWriteAdjQueryCount += 1;
1118                 }
1119         }
1120
1121         /**
1122          * Determine whether or not it is safe to retry queries after a database
1123          * connection is lost
1124          *
1125          * @param string $sql SQL query
1126          * @param bool $priorWritesPending Whether there is a transaction open with
1127          *     possible write queries or transaction pre-commit/idle callbacks
1128          *     waiting on it to finish.
1129          * @return bool True if it is safe to retry the query, false otherwise
1130          */
1131         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1132                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1133                 # Dropped connections also mean that named locks are automatically released.
1134                 # Only allow error suppression in autocommit mode or when the lost transaction
1135                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1136                 if ( $this->namedLocksHeld ) {
1137                         return false; // possible critical section violation
1138                 } elseif ( $sql === 'COMMIT' ) {
1139                         return !$priorWritesPending; // nothing written anyway? (T127428)
1140                 } elseif ( $sql === 'ROLLBACK' ) {
1141                         return true; // transaction lost...which is also what was requested :)
1142                 } elseif ( $this->explicitTrxActive() ) {
1143                         return false; // don't drop atomocity
1144                 } elseif ( $priorWritesPending ) {
1145                         return false; // prior writes lost from implicit transaction
1146                 }
1147
1148                 return true;
1149         }
1150
1151         /**
1152          * Clean things up after transaction loss due to disconnection
1153          *
1154          * @return null|Exception
1155          */
1156         private function handleSessionLoss() {
1157                 $this->trxLevel = 0;
1158                 $this->trxIdleCallbacks = []; // T67263
1159                 $this->trxPreCommitCallbacks = []; // T67263
1160                 $this->sessionTempTables = [];
1161                 $this->namedLocksHeld = [];
1162                 try {
1163                         // Handle callbacks in trxEndCallbacks
1164                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1165                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1166                         return null;
1167                 } catch ( Exception $e ) {
1168                         // Already logged; move on...
1169                         return $e;
1170                 }
1171         }
1172
1173         /**
1174          * Checks whether the cause of the error is detected to be a timeout.
1175          *
1176          * It returns false by default, and not all engines support detecting this yet.
1177          * If this returns false, it will be treated as a generic query error.
1178          *
1179          * @param string $error Error text
1180          * @param int $errno Error number
1181          * @return bool
1182          */
1183         protected function wasQueryTimeout( $error, $errno ) {
1184                 return false;
1185         }
1186
1187         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1188                 if ( $this->ignoreErrors() || $tempIgnore ) {
1189                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
1190                 } else {
1191                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1192                         $this->queryLogger->error(
1193                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1194                                 $this->getLogContext( [
1195                                         'method' => __METHOD__,
1196                                         'errno' => $errno,
1197                                         'error' => $error,
1198                                         'sql1line' => $sql1line,
1199                                         'fname' => $fname,
1200                                 ] )
1201                         );
1202                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
1203                         $wasQueryTimeout = $this->wasQueryTimeout( $error, $errno );
1204                         if ( $wasQueryTimeout ) {
1205                                 throw new DBQueryTimeoutError( $this, $error, $errno, $sql, $fname );
1206                         } else {
1207                                 throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1208                         }
1209                 }
1210         }
1211
1212         public function freeResult( $res ) {
1213         }
1214
1215         public function selectField(
1216                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1217         ) {
1218                 if ( $var === '*' ) { // sanity
1219                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1220                 }
1221
1222                 if ( !is_array( $options ) ) {
1223                         $options = [ $options ];
1224                 }
1225
1226                 $options['LIMIT'] = 1;
1227
1228                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1229                 if ( $res === false || !$this->numRows( $res ) ) {
1230                         return false;
1231                 }
1232
1233                 $row = $this->fetchRow( $res );
1234
1235                 if ( $row !== false ) {
1236                         return reset( $row );
1237                 } else {
1238                         return false;
1239                 }
1240         }
1241
1242         public function selectFieldValues(
1243                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1244         ) {
1245                 if ( $var === '*' ) { // sanity
1246                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1247                 } elseif ( !is_string( $var ) ) { // sanity
1248                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1249                 }
1250
1251                 if ( !is_array( $options ) ) {
1252                         $options = [ $options ];
1253                 }
1254
1255                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1256                 if ( $res === false ) {
1257                         return false;
1258                 }
1259
1260                 $values = [];
1261                 foreach ( $res as $row ) {
1262                         $values[] = $row->$var;
1263                 }
1264
1265                 return $values;
1266         }
1267
1268         /**
1269          * Returns an optional USE INDEX clause to go after the table, and a
1270          * string to go at the end of the query.
1271          *
1272          * @param array $options Associative array of options to be turned into
1273          *   an SQL query, valid keys are listed in the function.
1274          * @return array
1275          * @see Database::select()
1276          */
1277         protected function makeSelectOptions( $options ) {
1278                 $preLimitTail = $postLimitTail = '';
1279                 $startOpts = '';
1280
1281                 $noKeyOptions = [];
1282
1283                 foreach ( $options as $key => $option ) {
1284                         if ( is_numeric( $key ) ) {
1285                                 $noKeyOptions[$option] = true;
1286                         }
1287                 }
1288
1289                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1290
1291                 $preLimitTail .= $this->makeOrderBy( $options );
1292
1293                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1294                         $postLimitTail .= ' FOR UPDATE';
1295                 }
1296
1297                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1298                         $postLimitTail .= ' LOCK IN SHARE MODE';
1299                 }
1300
1301                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1302                         $startOpts .= 'DISTINCT';
1303                 }
1304
1305                 # Various MySQL extensions
1306                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1307                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1308                 }
1309
1310                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1311                         $startOpts .= ' HIGH_PRIORITY';
1312                 }
1313
1314                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1315                         $startOpts .= ' SQL_BIG_RESULT';
1316                 }
1317
1318                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1319                         $startOpts .= ' SQL_BUFFER_RESULT';
1320                 }
1321
1322                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1323                         $startOpts .= ' SQL_SMALL_RESULT';
1324                 }
1325
1326                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1327                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1328                 }
1329
1330                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1331                         $startOpts .= ' SQL_CACHE';
1332                 }
1333
1334                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1335                         $startOpts .= ' SQL_NO_CACHE';
1336                 }
1337
1338                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1339                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1340                 } else {
1341                         $useIndex = '';
1342                 }
1343                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1344                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1345                 } else {
1346                         $ignoreIndex = '';
1347                 }
1348
1349                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1350         }
1351
1352         /**
1353          * Returns an optional GROUP BY with an optional HAVING
1354          *
1355          * @param array $options Associative array of options
1356          * @return string
1357          * @see Database::select()
1358          * @since 1.21
1359          */
1360         protected function makeGroupByWithHaving( $options ) {
1361                 $sql = '';
1362                 if ( isset( $options['GROUP BY'] ) ) {
1363                         $gb = is_array( $options['GROUP BY'] )
1364                                 ? implode( ',', $options['GROUP BY'] )
1365                                 : $options['GROUP BY'];
1366                         $sql .= ' GROUP BY ' . $gb;
1367                 }
1368                 if ( isset( $options['HAVING'] ) ) {
1369                         $having = is_array( $options['HAVING'] )
1370                                 ? $this->makeList( $options['HAVING'], self::LIST_AND )
1371                                 : $options['HAVING'];
1372                         $sql .= ' HAVING ' . $having;
1373                 }
1374
1375                 return $sql;
1376         }
1377
1378         /**
1379          * Returns an optional ORDER BY
1380          *
1381          * @param array $options Associative array of options
1382          * @return string
1383          * @see Database::select()
1384          * @since 1.21
1385          */
1386         protected function makeOrderBy( $options ) {
1387                 if ( isset( $options['ORDER BY'] ) ) {
1388                         $ob = is_array( $options['ORDER BY'] )
1389                                 ? implode( ',', $options['ORDER BY'] )
1390                                 : $options['ORDER BY'];
1391
1392                         return ' ORDER BY ' . $ob;
1393                 }
1394
1395                 return '';
1396         }
1397
1398         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1399                 $options = [], $join_conds = [] ) {
1400                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1401
1402                 return $this->query( $sql, $fname );
1403         }
1404
1405         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1406                 $options = [], $join_conds = []
1407         ) {
1408                 if ( is_array( $vars ) ) {
1409                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1410                 }
1411
1412                 $options = (array)$options;
1413                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1414                         ? $options['USE INDEX']
1415                         : [];
1416                 $ignoreIndexes = (
1417                         isset( $options['IGNORE INDEX'] ) &&
1418                         is_array( $options['IGNORE INDEX'] )
1419                 )
1420                         ? $options['IGNORE INDEX']
1421                         : [];
1422
1423                 if ( is_array( $table ) ) {
1424                         $from = ' FROM ' .
1425                                 $this->tableNamesWithIndexClauseOrJOIN(
1426                                         $table, $useIndexes, $ignoreIndexes, $join_conds );
1427                 } elseif ( $table != '' ) {
1428                         $from = ' FROM ' .
1429                                 $this->tableNamesWithIndexClauseOrJOIN(
1430                                         [ $table ], $useIndexes, $ignoreIndexes, [] );
1431                 } else {
1432                         $from = '';
1433                 }
1434
1435                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1436                         $this->makeSelectOptions( $options );
1437
1438                 if ( !empty( $conds ) ) {
1439                         if ( is_array( $conds ) ) {
1440                                 $conds = $this->makeList( $conds, self::LIST_AND );
1441                         }
1442                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex " .
1443                                 "WHERE $conds $preLimitTail";
1444                 } else {
1445                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1446                 }
1447
1448                 if ( isset( $options['LIMIT'] ) ) {
1449                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1450                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1451                 }
1452                 $sql = "$sql $postLimitTail";
1453
1454                 if ( isset( $options['EXPLAIN'] ) ) {
1455                         $sql = 'EXPLAIN ' . $sql;
1456                 }
1457
1458                 return $sql;
1459         }
1460
1461         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1462                 $options = [], $join_conds = []
1463         ) {
1464                 $options = (array)$options;
1465                 $options['LIMIT'] = 1;
1466                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1467
1468                 if ( $res === false ) {
1469                         return false;
1470                 }
1471
1472                 if ( !$this->numRows( $res ) ) {
1473                         return false;
1474                 }
1475
1476                 $obj = $this->fetchObject( $res );
1477
1478                 return $obj;
1479         }
1480
1481         public function estimateRowCount(
1482                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1483         ) {
1484                 $rows = 0;
1485                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1486
1487                 if ( $res ) {
1488                         $row = $this->fetchRow( $res );
1489                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1490                 }
1491
1492                 return $rows;
1493         }
1494
1495         public function selectRowCount(
1496                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1497         ) {
1498                 $rows = 0;
1499                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1500                 // The identifier quotes is primarily for MSSQL.
1501                 $rowCountCol = $this->addIdentifierQuotes( "rowcount" );
1502                 $tableName = $this->addIdentifierQuotes( "tmp_count" );
1503                 $res = $this->query( "SELECT COUNT(*) AS $rowCountCol FROM ($sql) $tableName", $fname );
1504
1505                 if ( $res ) {
1506                         $row = $this->fetchRow( $res );
1507                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1508                 }
1509
1510                 return $rows;
1511         }
1512
1513         /**
1514          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1515          * It's only slightly flawed. Don't use for anything important.
1516          *
1517          * @param string $sql A SQL Query
1518          *
1519          * @return string
1520          */
1521         protected static function generalizeSQL( $sql ) {
1522                 # This does the same as the regexp below would do, but in such a way
1523                 # as to avoid crashing php on some large strings.
1524                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1525
1526                 $sql = str_replace( "\\\\", '', $sql );
1527                 $sql = str_replace( "\\'", '', $sql );
1528                 $sql = str_replace( "\\\"", '', $sql );
1529                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1530                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1531
1532                 # All newlines, tabs, etc replaced by single space
1533                 $sql = preg_replace( '/\s+/', ' ', $sql );
1534
1535                 # All numbers => N,
1536                 # except the ones surrounded by characters, e.g. l10n
1537                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1538                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1539
1540                 return $sql;
1541         }
1542
1543         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1544                 $info = $this->fieldInfo( $table, $field );
1545
1546                 return (bool)$info;
1547         }
1548
1549         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1550                 if ( !$this->tableExists( $table ) ) {
1551                         return null;
1552                 }
1553
1554                 $info = $this->indexInfo( $table, $index, $fname );
1555                 if ( is_null( $info ) ) {
1556                         return null;
1557                 } else {
1558                         return $info !== false;
1559                 }
1560         }
1561
1562         public function tableExists( $table, $fname = __METHOD__ ) {
1563                 $tableRaw = $this->tableName( $table, 'raw' );
1564                 if ( isset( $this->sessionTempTables[$tableRaw] ) ) {
1565                         return true; // already known to exist
1566                 }
1567
1568                 $table = $this->tableName( $table );
1569                 $ignoreErrors = true;
1570                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname, $ignoreErrors );
1571
1572                 return (bool)$res;
1573         }
1574
1575         public function indexUnique( $table, $index ) {
1576                 $indexInfo = $this->indexInfo( $table, $index );
1577
1578                 if ( !$indexInfo ) {
1579                         return null;
1580                 }
1581
1582                 return !$indexInfo[0]->Non_unique;
1583         }
1584
1585         /**
1586          * Helper for Database::insert().
1587          *
1588          * @param array $options
1589          * @return string
1590          */
1591         protected function makeInsertOptions( $options ) {
1592                 return implode( ' ', $options );
1593         }
1594
1595         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1596                 # No rows to insert, easy just return now
1597                 if ( !count( $a ) ) {
1598                         return true;
1599                 }
1600
1601                 $table = $this->tableName( $table );
1602
1603                 if ( !is_array( $options ) ) {
1604                         $options = [ $options ];
1605                 }
1606
1607                 $fh = null;
1608                 if ( isset( $options['fileHandle'] ) ) {
1609                         $fh = $options['fileHandle'];
1610                 }
1611                 $options = $this->makeInsertOptions( $options );
1612
1613                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1614                         $multi = true;
1615                         $keys = array_keys( $a[0] );
1616                 } else {
1617                         $multi = false;
1618                         $keys = array_keys( $a );
1619                 }
1620
1621                 $sql = 'INSERT ' . $options .
1622                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1623
1624                 if ( $multi ) {
1625                         $first = true;
1626                         foreach ( $a as $row ) {
1627                                 if ( $first ) {
1628                                         $first = false;
1629                                 } else {
1630                                         $sql .= ',';
1631                                 }
1632                                 $sql .= '(' . $this->makeList( $row ) . ')';
1633                         }
1634                 } else {
1635                         $sql .= '(' . $this->makeList( $a ) . ')';
1636                 }
1637
1638                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1639                         return false;
1640                 } elseif ( $fh !== null ) {
1641                         return true;
1642                 }
1643
1644                 return (bool)$this->query( $sql, $fname );
1645         }
1646
1647         /**
1648          * Make UPDATE options array for Database::makeUpdateOptions
1649          *
1650          * @param array $options
1651          * @return array
1652          */
1653         protected function makeUpdateOptionsArray( $options ) {
1654                 if ( !is_array( $options ) ) {
1655                         $options = [ $options ];
1656                 }
1657
1658                 $opts = [];
1659
1660                 if ( in_array( 'IGNORE', $options ) ) {
1661                         $opts[] = 'IGNORE';
1662                 }
1663
1664                 return $opts;
1665         }
1666
1667         /**
1668          * Make UPDATE options for the Database::update function
1669          *
1670          * @param array $options The options passed to Database::update
1671          * @return string
1672          */
1673         protected function makeUpdateOptions( $options ) {
1674                 $opts = $this->makeUpdateOptionsArray( $options );
1675
1676                 return implode( ' ', $opts );
1677         }
1678
1679         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1680                 $table = $this->tableName( $table );
1681                 $opts = $this->makeUpdateOptions( $options );
1682                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, self::LIST_SET );
1683
1684                 if ( $conds !== [] && $conds !== '*' ) {
1685                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1686                 }
1687
1688                 return (bool)$this->query( $sql, $fname );
1689         }
1690
1691         public function makeList( $a, $mode = self::LIST_COMMA ) {
1692                 if ( !is_array( $a ) ) {
1693                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1694                 }
1695
1696                 $first = true;
1697                 $list = '';
1698
1699                 foreach ( $a as $field => $value ) {
1700                         if ( !$first ) {
1701                                 if ( $mode == self::LIST_AND ) {
1702                                         $list .= ' AND ';
1703                                 } elseif ( $mode == self::LIST_OR ) {
1704                                         $list .= ' OR ';
1705                                 } else {
1706                                         $list .= ',';
1707                                 }
1708                         } else {
1709                                 $first = false;
1710                         }
1711
1712                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1713                                 $list .= "($value)";
1714                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1715                                 $list .= "$value";
1716                         } elseif (
1717                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1718                         ) {
1719                                 // Remove null from array to be handled separately if found
1720                                 $includeNull = false;
1721                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1722                                         $includeNull = true;
1723                                         unset( $value[$nullKey] );
1724                                 }
1725                                 if ( count( $value ) == 0 && !$includeNull ) {
1726                                         throw new InvalidArgumentException(
1727                                                 __METHOD__ . ": empty input for field $field" );
1728                                 } elseif ( count( $value ) == 0 ) {
1729                                         // only check if $field is null
1730                                         $list .= "$field IS NULL";
1731                                 } else {
1732                                         // IN clause contains at least one valid element
1733                                         if ( $includeNull ) {
1734                                                 // Group subconditions to ensure correct precedence
1735                                                 $list .= '(';
1736                                         }
1737                                         if ( count( $value ) == 1 ) {
1738                                                 // Special-case single values, as IN isn't terribly efficient
1739                                                 // Don't necessarily assume the single key is 0; we don't
1740                                                 // enforce linear numeric ordering on other arrays here.
1741                                                 $value = array_values( $value )[0];
1742                                                 $list .= $field . " = " . $this->addQuotes( $value );
1743                                         } else {
1744                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1745                                         }
1746                                         // if null present in array, append IS NULL
1747                                         if ( $includeNull ) {
1748                                                 $list .= " OR $field IS NULL)";
1749                                         }
1750                                 }
1751                         } elseif ( $value === null ) {
1752                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1753                                         $list .= "$field IS ";
1754                                 } elseif ( $mode == self::LIST_SET ) {
1755                                         $list .= "$field = ";
1756                                 }
1757                                 $list .= 'NULL';
1758                         } else {
1759                                 if (
1760                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1761                                 ) {
1762                                         $list .= "$field = ";
1763                                 }
1764                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1765                         }
1766                 }
1767
1768                 return $list;
1769         }
1770
1771         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1772                 $conds = [];
1773
1774                 foreach ( $data as $base => $sub ) {
1775                         if ( count( $sub ) ) {
1776                                 $conds[] = $this->makeList(
1777                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1778                                         self::LIST_AND );
1779                         }
1780                 }
1781
1782                 if ( $conds ) {
1783                         return $this->makeList( $conds, self::LIST_OR );
1784                 } else {
1785                         // Nothing to search for...
1786                         return false;
1787                 }
1788         }
1789
1790         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1791                 return $valuename;
1792         }
1793
1794         public function bitNot( $field ) {
1795                 return "(~$field)";
1796         }
1797
1798         public function bitAnd( $fieldLeft, $fieldRight ) {
1799                 return "($fieldLeft & $fieldRight)";
1800         }
1801
1802         public function bitOr( $fieldLeft, $fieldRight ) {
1803                 return "($fieldLeft | $fieldRight)";
1804         }
1805
1806         public function buildConcat( $stringList ) {
1807                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1808         }
1809
1810         public function buildGroupConcatField(
1811                 $delim, $table, $field, $conds = '', $join_conds = []
1812         ) {
1813                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1814
1815                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1816         }
1817
1818         public function buildStringCast( $field ) {
1819                 return $field;
1820         }
1821
1822         public function databasesAreIndependent() {
1823                 return false;
1824         }
1825
1826         public function selectDB( $db ) {
1827                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1828                 # if your database engine supports a concept similar to MySQL's
1829                 # databases you may as well.
1830                 $this->dbName = $db;
1831
1832                 return true;
1833         }
1834
1835         public function getDBname() {
1836                 return $this->dbName;
1837         }
1838
1839         public function getServer() {
1840                 return $this->server;
1841         }
1842
1843         public function tableName( $name, $format = 'quoted' ) {
1844                 # Skip the entire process when we have a string quoted on both ends.
1845                 # Note that we check the end so that we will still quote any use of
1846                 # use of `database`.table. But won't break things if someone wants
1847                 # to query a database table with a dot in the name.
1848                 if ( $this->isQuotedIdentifier( $name ) ) {
1849                         return $name;
1850                 }
1851
1852                 # Lets test for any bits of text that should never show up in a table
1853                 # name. Basically anything like JOIN or ON which are actually part of
1854                 # SQL queries, but may end up inside of the table value to combine
1855                 # sql. Such as how the API is doing.
1856                 # Note that we use a whitespace test rather than a \b test to avoid
1857                 # any remote case where a word like on may be inside of a table name
1858                 # surrounded by symbols which may be considered word breaks.
1859                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1860                         return $name;
1861                 }
1862
1863                 # Split database and table into proper variables.
1864                 list( $database, $schema, $prefix, $table ) = $this->qualifiedTableComponents( $name );
1865
1866                 # Quote $table and apply the prefix if not quoted.
1867                 # $tableName might be empty if this is called from Database::replaceVars()
1868                 $tableName = "{$prefix}{$table}";
1869                 if ( $format === 'quoted'
1870                         && !$this->isQuotedIdentifier( $tableName )
1871                         && $tableName !== ''
1872                 ) {
1873                         $tableName = $this->addIdentifierQuotes( $tableName );
1874                 }
1875
1876                 # Quote $schema and $database and merge them with the table name if needed
1877                 $tableName = $this->prependDatabaseOrSchema( $schema, $tableName, $format );
1878                 $tableName = $this->prependDatabaseOrSchema( $database, $tableName, $format );
1879
1880                 return $tableName;
1881         }
1882
1883         /**
1884          * Get the table components needed for a query given the currently selected database
1885          *
1886          * @param string $name Table name in the form of db.schema.table, db.table, or table
1887          * @return array (DB name or "" for default, schema name, table prefix, table name)
1888          */
1889         protected function qualifiedTableComponents( $name ) {
1890                 # We reverse the explode so that database.table and table both output the correct table.
1891                 $dbDetails = explode( '.', $name, 3 );
1892                 if ( count( $dbDetails ) == 3 ) {
1893                         list( $database, $schema, $table ) = $dbDetails;
1894                         # We don't want any prefix added in this case
1895                         $prefix = '';
1896                 } elseif ( count( $dbDetails ) == 2 ) {
1897                         list( $database, $table ) = $dbDetails;
1898                         # We don't want any prefix added in this case
1899                         $prefix = '';
1900                         # In dbs that support it, $database may actually be the schema
1901                         # but that doesn't affect any of the functionality here
1902                         $schema = '';
1903                 } else {
1904                         list( $table ) = $dbDetails;
1905                         if ( isset( $this->tableAliases[$table] ) ) {
1906                                 $database = $this->tableAliases[$table]['dbname'];
1907                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1908                                         ? $this->tableAliases[$table]['schema']
1909                                         : $this->schema;
1910                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1911                                         ? $this->tableAliases[$table]['prefix']
1912                                         : $this->tablePrefix;
1913                         } else {
1914                                 $database = '';
1915                                 $schema = $this->schema; # Default schema
1916                                 $prefix = $this->tablePrefix; # Default prefix
1917                         }
1918                 }
1919
1920                 return [ $database, $schema, $prefix, $table ];
1921         }
1922
1923         /**
1924          * @param string|null $namespace Database or schema
1925          * @param string $relation Name of table, view, sequence, etc...
1926          * @param string $format One of (raw, quoted)
1927          * @return string Relation name with quoted and merged $namespace as needed
1928          */
1929         private function prependDatabaseOrSchema( $namespace, $relation, $format ) {
1930                 if ( strlen( $namespace ) ) {
1931                         if ( $format === 'quoted' && !$this->isQuotedIdentifier( $namespace ) ) {
1932                                 $namespace = $this->addIdentifierQuotes( $namespace );
1933                         }
1934                         $relation = $namespace . '.' . $relation;
1935                 }
1936
1937                 return $relation;
1938         }
1939
1940         public function tableNames() {
1941                 $inArray = func_get_args();
1942                 $retVal = [];
1943
1944                 foreach ( $inArray as $name ) {
1945                         $retVal[$name] = $this->tableName( $name );
1946                 }
1947
1948                 return $retVal;
1949         }
1950
1951         public function tableNamesN() {
1952                 $inArray = func_get_args();
1953                 $retVal = [];
1954
1955                 foreach ( $inArray as $name ) {
1956                         $retVal[] = $this->tableName( $name );
1957                 }
1958
1959                 return $retVal;
1960         }
1961
1962         /**
1963          * Get an aliased table name
1964          * e.g. tableName AS newTableName
1965          *
1966          * @param string $name Table name, see tableName()
1967          * @param string|bool $alias Alias (optional)
1968          * @return string SQL name for aliased table. Will not alias a table to its own name
1969          */
1970         protected function tableNameWithAlias( $name, $alias = false ) {
1971                 if ( !$alias || $alias == $name ) {
1972                         return $this->tableName( $name );
1973                 } else {
1974                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1975                 }
1976         }
1977
1978         /**
1979          * Gets an array of aliased table names
1980          *
1981          * @param array $tables [ [alias] => table ]
1982          * @return string[] See tableNameWithAlias()
1983          */
1984         protected function tableNamesWithAlias( $tables ) {
1985                 $retval = [];
1986                 foreach ( $tables as $alias => $table ) {
1987                         if ( is_numeric( $alias ) ) {
1988                                 $alias = $table;
1989                         }
1990                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1991                 }
1992
1993                 return $retval;
1994         }
1995
1996         /**
1997          * Get an aliased field name
1998          * e.g. fieldName AS newFieldName
1999          *
2000          * @param string $name Field name
2001          * @param string|bool $alias Alias (optional)
2002          * @return string SQL name for aliased field. Will not alias a field to its own name
2003          */
2004         protected function fieldNameWithAlias( $name, $alias = false ) {
2005                 if ( !$alias || (string)$alias === (string)$name ) {
2006                         return $name;
2007                 } else {
2008                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2009                 }
2010         }
2011
2012         /**
2013          * Gets an array of aliased field names
2014          *
2015          * @param array $fields [ [alias] => field ]
2016          * @return string[] See fieldNameWithAlias()
2017          */
2018         protected function fieldNamesWithAlias( $fields ) {
2019                 $retval = [];
2020                 foreach ( $fields as $alias => $field ) {
2021                         if ( is_numeric( $alias ) ) {
2022                                 $alias = $field;
2023                         }
2024                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2025                 }
2026
2027                 return $retval;
2028         }
2029
2030         /**
2031          * Get the aliased table name clause for a FROM clause
2032          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2033          *
2034          * @param array $tables ( [alias] => table )
2035          * @param array $use_index Same as for select()
2036          * @param array $ignore_index Same as for select()
2037          * @param array $join_conds Same as for select()
2038          * @return string
2039          */
2040         protected function tableNamesWithIndexClauseOrJOIN(
2041                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2042         ) {
2043                 $ret = [];
2044                 $retJOIN = [];
2045                 $use_index = (array)$use_index;
2046                 $ignore_index = (array)$ignore_index;
2047                 $join_conds = (array)$join_conds;
2048
2049                 foreach ( $tables as $alias => $table ) {
2050                         if ( !is_string( $alias ) ) {
2051                                 // No alias? Set it equal to the table name
2052                                 $alias = $table;
2053                         }
2054
2055                         if ( is_array( $table ) ) {
2056                                 // A parenthesized group
2057                                 if ( count( $table ) > 1 ) {
2058                                         $joinedTable = '('
2059                                                 . $this->tableNamesWithIndexClauseOrJOIN( $table, $use_index, $ignore_index, $join_conds )
2060                                                 . ')';
2061                                 } else {
2062                                         // Degenerate case
2063                                         $innerTable = reset( $table );
2064                                         $innerAlias = key( $table );
2065                                         $joinedTable = $this->tableNameWithAlias(
2066                                                 $innerTable,
2067                                                 is_string( $innerAlias ) ? $innerAlias : $innerTable
2068                                         );
2069                                 }
2070                         } else {
2071                                 $joinedTable = $this->tableNameWithAlias( $table, $alias );
2072                         }
2073
2074                         // Is there a JOIN clause for this table?
2075                         if ( isset( $join_conds[$alias] ) ) {
2076                                 list( $joinType, $conds ) = $join_conds[$alias];
2077                                 $tableClause = $joinType;
2078                                 $tableClause .= ' ' . $joinedTable;
2079                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2080                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2081                                         if ( $use != '' ) {
2082                                                 $tableClause .= ' ' . $use;
2083                                         }
2084                                 }
2085                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2086                                         $ignore = $this->ignoreIndexClause(
2087                                                 implode( ',', (array)$ignore_index[$alias] ) );
2088                                         if ( $ignore != '' ) {
2089                                                 $tableClause .= ' ' . $ignore;
2090                                         }
2091                                 }
2092                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
2093                                 if ( $on != '' ) {
2094                                         $tableClause .= ' ON (' . $on . ')';
2095                                 }
2096
2097                                 $retJOIN[] = $tableClause;
2098                         } elseif ( isset( $use_index[$alias] ) ) {
2099                                 // Is there an INDEX clause for this table?
2100                                 $tableClause = $joinedTable;
2101                                 $tableClause .= ' ' . $this->useIndexClause(
2102                                                 implode( ',', (array)$use_index[$alias] )
2103                                         );
2104
2105                                 $ret[] = $tableClause;
2106                         } elseif ( isset( $ignore_index[$alias] ) ) {
2107                                 // Is there an INDEX clause for this table?
2108                                 $tableClause = $joinedTable;
2109                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2110                                                 implode( ',', (array)$ignore_index[$alias] )
2111                                         );
2112
2113                                 $ret[] = $tableClause;
2114                         } else {
2115                                 $tableClause = $joinedTable;
2116
2117                                 $ret[] = $tableClause;
2118                         }
2119                 }
2120
2121                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2122                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2123                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2124
2125                 // Compile our final table clause
2126                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2127         }
2128
2129         /**
2130          * Allows for index remapping in queries where this is not consistent across DBMS
2131          *
2132          * @param string $index
2133          * @return string
2134          */
2135         protected function indexName( $index ) {
2136                 return $index;
2137         }
2138
2139         public function addQuotes( $s ) {
2140                 if ( $s instanceof Blob ) {
2141                         $s = $s->fetch();
2142                 }
2143                 if ( $s === null ) {
2144                         return 'NULL';
2145                 } elseif ( is_bool( $s ) ) {
2146                         return (int)$s;
2147                 } else {
2148                         # This will also quote numeric values. This should be harmless,
2149                         # and protects against weird problems that occur when they really
2150                         # _are_ strings such as article titles and string->number->string
2151                         # conversion is not 1:1.
2152                         return "'" . $this->strencode( $s ) . "'";
2153                 }
2154         }
2155
2156         /**
2157          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2158          * MySQL uses `backticks` while basically everything else uses double quotes.
2159          * Since MySQL is the odd one out here the double quotes are our generic
2160          * and we implement backticks in DatabaseMysqlBase.
2161          *
2162          * @param string $s
2163          * @return string
2164          */
2165         public function addIdentifierQuotes( $s ) {
2166                 return '"' . str_replace( '"', '""', $s ) . '"';
2167         }
2168
2169         /**
2170          * Returns if the given identifier looks quoted or not according to
2171          * the database convention for quoting identifiers .
2172          *
2173          * @note Do not use this to determine if untrusted input is safe.
2174          *   A malicious user can trick this function.
2175          * @param string $name
2176          * @return bool
2177          */
2178         public function isQuotedIdentifier( $name ) {
2179                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2180         }
2181
2182         /**
2183          * @param string $s
2184          * @param string $escapeChar
2185          * @return string
2186          */
2187         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
2188                 return str_replace( [ $escapeChar, '%', '_' ],
2189                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_" ],
2190                         $s );
2191         }
2192
2193         public function buildLike() {
2194                 $params = func_get_args();
2195
2196                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2197                         $params = $params[0];
2198                 }
2199
2200                 $s = '';
2201
2202                 // We use ` instead of \ as the default LIKE escape character, since addQuotes()
2203                 // may escape backslashes, creating problems of double escaping. The `
2204                 // character has good cross-DBMS compatibility, avoiding special operators
2205                 // in MS SQL like ^ and %
2206                 $escapeChar = '`';
2207
2208                 foreach ( $params as $value ) {
2209                         if ( $value instanceof LikeMatch ) {
2210                                 $s .= $value->toString();
2211                         } else {
2212                                 $s .= $this->escapeLikeInternal( $value, $escapeChar );
2213                         }
2214                 }
2215
2216                 return ' LIKE ' . $this->addQuotes( $s ) . ' ESCAPE ' . $this->addQuotes( $escapeChar ) . ' ';
2217         }
2218
2219         public function anyChar() {
2220                 return new LikeMatch( '_' );
2221         }
2222
2223         public function anyString() {
2224                 return new LikeMatch( '%' );
2225         }
2226
2227         public function nextSequenceValue( $seqName ) {
2228                 return null;
2229         }
2230
2231         /**
2232          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2233          * is only needed because a) MySQL must be as efficient as possible due to
2234          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2235          * which index to pick. Anyway, other databases might have different
2236          * indexes on a given table. So don't bother overriding this unless you're
2237          * MySQL.
2238          * @param string $index
2239          * @return string
2240          */
2241         public function useIndexClause( $index ) {
2242                 return '';
2243         }
2244
2245         /**
2246          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2247          * is only needed because a) MySQL must be as efficient as possible due to
2248          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2249          * which index to pick. Anyway, other databases might have different
2250          * indexes on a given table. So don't bother overriding this unless you're
2251          * MySQL.
2252          * @param string $index
2253          * @return string
2254          */
2255         public function ignoreIndexClause( $index ) {
2256                 return '';
2257         }
2258
2259         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2260                 if ( count( $rows ) == 0 ) {
2261                         return;
2262                 }
2263
2264                 // Single row case
2265                 if ( !is_array( reset( $rows ) ) ) {
2266                         $rows = [ $rows ];
2267                 }
2268
2269                 try {
2270                         $this->startAtomic( $fname );
2271                         $affectedRowCount = 0;
2272                         foreach ( $rows as $row ) {
2273                                 // Delete rows which collide with this one
2274                                 $indexWhereClauses = [];
2275                                 foreach ( $uniqueIndexes as $index ) {
2276                                         $indexColumns = (array)$index;
2277                                         $indexRowValues = array_intersect_key( $row, array_flip( $indexColumns ) );
2278                                         if ( count( $indexRowValues ) != count( $indexColumns ) ) {
2279                                                 throw new DBUnexpectedError(
2280                                                         $this,
2281                                                         'New record does not provide all values for unique key (' .
2282                                                         implode( ', ', $indexColumns ) . ')'
2283                                                 );
2284                                         } elseif ( in_array( null, $indexRowValues, true ) ) {
2285                                                 throw new DBUnexpectedError(
2286                                                         $this,
2287                                                         'New record has a null value for unique key (' .
2288                                                         implode( ', ', $indexColumns ) . ')'
2289                                                 );
2290                                         }
2291                                         $indexWhereClauses[] = $this->makeList( $indexRowValues, LIST_AND );
2292                                 }
2293
2294                                 if ( $indexWhereClauses ) {
2295                                         $this->delete( $table, $this->makeList( $indexWhereClauses, LIST_OR ), $fname );
2296                                         $affectedRowCount += $this->affectedRows();
2297                                 }
2298
2299                                 // Now insert the row
2300                                 $this->insert( $table, $row, $fname );
2301                                 $affectedRowCount += $this->affectedRows();
2302                         }
2303                         $this->endAtomic( $fname );
2304                         $this->affectedRowCount = $affectedRowCount;
2305                 } catch ( Exception $e ) {
2306                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2307                         throw $e;
2308                 }
2309         }
2310
2311         /**
2312          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2313          * statement.
2314          *
2315          * @param string $table Table name
2316          * @param array|string $rows Row(s) to insert
2317          * @param string $fname Caller function name
2318          *
2319          * @return ResultWrapper
2320          */
2321         protected function nativeReplace( $table, $rows, $fname ) {
2322                 $table = $this->tableName( $table );
2323
2324                 # Single row case
2325                 if ( !is_array( reset( $rows ) ) ) {
2326                         $rows = [ $rows ];
2327                 }
2328
2329                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2330                 $first = true;
2331
2332                 foreach ( $rows as $row ) {
2333                         if ( $first ) {
2334                                 $first = false;
2335                         } else {
2336                                 $sql .= ',';
2337                         }
2338
2339                         $sql .= '(' . $this->makeList( $row ) . ')';
2340                 }
2341
2342                 return $this->query( $sql, $fname );
2343         }
2344
2345         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2346                 $fname = __METHOD__
2347         ) {
2348                 if ( !count( $rows ) ) {
2349                         return true; // nothing to do
2350                 }
2351
2352                 if ( !is_array( reset( $rows ) ) ) {
2353                         $rows = [ $rows ];
2354                 }
2355
2356                 if ( count( $uniqueIndexes ) ) {
2357                         $clauses = []; // list WHERE clauses that each identify a single row
2358                         foreach ( $rows as $row ) {
2359                                 foreach ( $uniqueIndexes as $index ) {
2360                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2361                                         $rowKey = []; // unique key to this row
2362                                         foreach ( $index as $column ) {
2363                                                 $rowKey[$column] = $row[$column];
2364                                         }
2365                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2366                                 }
2367                         }
2368                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2369                 } else {
2370                         $where = false;
2371                 }
2372
2373                 $affectedRowCount = 0;
2374                 try {
2375                         $this->startAtomic( $fname );
2376                         # Update any existing conflicting row(s)
2377                         if ( $where !== false ) {
2378                                 $ok = $this->update( $table, $set, $where, $fname );
2379                                 $affectedRowCount += $this->affectedRows();
2380                         } else {
2381                                 $ok = true;
2382                         }
2383                         # Now insert any non-conflicting row(s)
2384                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2385                         $affectedRowCount += $this->affectedRows();
2386                         $this->endAtomic( $fname );
2387                         $this->affectedRowCount = $affectedRowCount;
2388                 } catch ( Exception $e ) {
2389                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2390                         throw $e;
2391                 }
2392
2393                 return $ok;
2394         }
2395
2396         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2397                 $fname = __METHOD__
2398         ) {
2399                 if ( !$conds ) {
2400                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2401                 }
2402
2403                 $delTable = $this->tableName( $delTable );
2404                 $joinTable = $this->tableName( $joinTable );
2405                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2406                 if ( $conds != '*' ) {
2407                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2408                 }
2409                 $sql .= ')';
2410
2411                 $this->query( $sql, $fname );
2412         }
2413
2414         public function textFieldSize( $table, $field ) {
2415                 $table = $this->tableName( $table );
2416                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2417                 $res = $this->query( $sql, __METHOD__ );
2418                 $row = $this->fetchObject( $res );
2419
2420                 $m = [];
2421
2422                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2423                         $size = $m[1];
2424                 } else {
2425                         $size = -1;
2426                 }
2427
2428                 return $size;
2429         }
2430
2431         public function delete( $table, $conds, $fname = __METHOD__ ) {
2432                 if ( !$conds ) {
2433                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2434                 }
2435
2436                 $table = $this->tableName( $table );
2437                 $sql = "DELETE FROM $table";
2438
2439                 if ( $conds != '*' ) {
2440                         if ( is_array( $conds ) ) {
2441                                 $conds = $this->makeList( $conds, self::LIST_AND );
2442                         }
2443                         $sql .= ' WHERE ' . $conds;
2444                 }
2445
2446                 return $this->query( $sql, $fname );
2447         }
2448
2449         public function insertSelect(
2450                 $destTable, $srcTable, $varMap, $conds,
2451                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2452         ) {
2453                 if ( $this->cliMode ) {
2454                         // For massive migrations with downtime, we don't want to select everything
2455                         // into memory and OOM, so do all this native on the server side if possible.
2456                         return $this->nativeInsertSelect(
2457                                 $destTable,
2458                                 $srcTable,
2459                                 $varMap,
2460                                 $conds,
2461                                 $fname,
2462                                 $insertOptions,
2463                                 $selectOptions,
2464                                 $selectJoinConds
2465                         );
2466                 }
2467
2468                 return $this->nonNativeInsertSelect(
2469                         $destTable,
2470                         $srcTable,
2471                         $varMap,
2472                         $conds,
2473                         $fname,
2474                         $insertOptions,
2475                         $selectOptions,
2476                         $selectJoinConds
2477                 );
2478         }
2479
2480         /**
2481          * Implementation of insertSelect() based on select() and insert()
2482          *
2483          * @see IDatabase::insertSelect()
2484          * @since 1.30
2485          * @param string $destTable
2486          * @param string|array $srcTable
2487          * @param array $varMap
2488          * @param array $conds
2489          * @param string $fname
2490          * @param array $insertOptions
2491          * @param array $selectOptions
2492          * @param array $selectJoinConds
2493          * @return bool
2494          */
2495         protected function nonNativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2496                 $fname = __METHOD__,
2497                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2498         ) {
2499                 $insertOptions = array_diff( (array)$insertOptions, [ 'NO_AUTO_COLUMNS' ] );
2500
2501                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2502                 // on only the master (without needing row-based-replication). It also makes it easy to
2503                 // know how big the INSERT is going to be.
2504                 $fields = [];
2505                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2506                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2507                 }
2508                 $selectOptions[] = 'FOR UPDATE';
2509                 $res = $this->select(
2510                         $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions, $selectJoinConds
2511                 );
2512                 if ( !$res ) {
2513                         return false;
2514                 }
2515
2516                 try {
2517                         $affectedRowCount = 0;
2518                         $this->startAtomic( $fname );
2519                         $rows = [];
2520                         $ok = true;
2521                         foreach ( $res as $row ) {
2522                                 $rows[] = (array)$row;
2523
2524                                 // Avoid inserts that are too huge
2525                                 if ( count( $rows ) >= $this->nonNativeInsertSelectBatchSize ) {
2526                                         $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2527                                         if ( !$ok ) {
2528                                                 break;
2529                                         }
2530                                         $affectedRowCount += $this->affectedRows();
2531                                         $rows = [];
2532                                 }
2533                         }
2534                         if ( $rows && $ok ) {
2535                                 $ok = $this->insert( $destTable, $rows, $fname, $insertOptions );
2536                                 if ( $ok ) {
2537                                         $affectedRowCount += $this->affectedRows();
2538                                 }
2539                         }
2540                         if ( $ok ) {
2541                                 $this->endAtomic( $fname );
2542                                 $this->affectedRowCount = $affectedRowCount;
2543                         } else {
2544                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2545                         }
2546                         return $ok;
2547                 } catch ( Exception $e ) {
2548                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2549                         throw $e;
2550                 }
2551         }
2552
2553         /**
2554          * Native server-side implementation of insertSelect() for situations where
2555          * we don't want to select everything into memory
2556          *
2557          * @see IDatabase::insertSelect()
2558          * @param string $destTable
2559          * @param string|array $srcTable
2560          * @param array $varMap
2561          * @param array $conds
2562          * @param string $fname
2563          * @param array $insertOptions
2564          * @param array $selectOptions
2565          * @param array $selectJoinConds
2566          * @return bool
2567          */
2568         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2569                 $fname = __METHOD__,
2570                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
2571         ) {
2572                 $destTable = $this->tableName( $destTable );
2573
2574                 if ( !is_array( $insertOptions ) ) {
2575                         $insertOptions = [ $insertOptions ];
2576                 }
2577                 $insertOptions = array_diff( (array)$insertOptions, [ 'NO_AUTO_COLUMNS' ] );
2578
2579                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2580
2581                 $selectSql = $this->selectSQLText(
2582                         $srcTable,
2583                         array_values( $varMap ),
2584                         $conds,
2585                         $fname,
2586                         $selectOptions,
2587                         $selectJoinConds
2588                 );
2589
2590                 $sql = "INSERT $insertOptions" .
2591                         " INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
2592                         $selectSql;
2593
2594                 return $this->query( $sql, $fname );
2595         }
2596
2597         /**
2598          * Construct a LIMIT query with optional offset. This is used for query
2599          * pages. The SQL should be adjusted so that only the first $limit rows
2600          * are returned. If $offset is provided as well, then the first $offset
2601          * rows should be discarded, and the next $limit rows should be returned.
2602          * If the result of the query is not ordered, then the rows to be returned
2603          * are theoretically arbitrary.
2604          *
2605          * $sql is expected to be a SELECT, if that makes a difference.
2606          *
2607          * The version provided by default works in MySQL and SQLite. It will very
2608          * likely need to be overridden for most other DBMSes.
2609          *
2610          * @param string $sql SQL query we will append the limit too
2611          * @param int $limit The SQL limit
2612          * @param int|bool $offset The SQL offset (default false)
2613          * @throws DBUnexpectedError
2614          * @return string
2615          */
2616         public function limitResult( $sql, $limit, $offset = false ) {
2617                 if ( !is_numeric( $limit ) ) {
2618                         throw new DBUnexpectedError( $this,
2619                                 "Invalid non-numeric limit passed to limitResult()\n" );
2620                 }
2621
2622                 return "$sql LIMIT "
2623                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2624                 . "{$limit} ";
2625         }
2626
2627         public function unionSupportsOrderAndLimit() {
2628                 return true; // True for almost every DB supported
2629         }
2630
2631         public function unionQueries( $sqls, $all ) {
2632                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2633
2634                 return '(' . implode( $glue, $sqls ) . ')';
2635         }
2636
2637         public function unionConditionPermutations(
2638                 $table, $vars, array $permute_conds, $extra_conds = '', $fname = __METHOD__,
2639                 $options = [], $join_conds = []
2640         ) {
2641                 // First, build the Cartesian product of $permute_conds
2642                 $conds = [ [] ];
2643                 foreach ( $permute_conds as $field => $values ) {
2644                         if ( !$values ) {
2645                                 // Skip empty $values
2646                                 continue;
2647                         }
2648                         $values = array_unique( $values ); // For sanity
2649                         $newConds = [];
2650                         foreach ( $conds as $cond ) {
2651                                 foreach ( $values as $value ) {
2652                                         $cond[$field] = $value;
2653                                         $newConds[] = $cond; // Arrays are by-value, not by-reference, so this works
2654                                 }
2655                         }
2656                         $conds = $newConds;
2657                 }
2658
2659                 $extra_conds = $extra_conds === '' ? [] : (array)$extra_conds;
2660
2661                 // If there's just one condition and no subordering, hand off to
2662                 // selectSQLText directly.
2663                 if ( count( $conds ) === 1 &&
2664                         ( !isset( $options['INNER ORDER BY'] ) || !$this->unionSupportsOrderAndLimit() )
2665                 ) {
2666                         return $this->selectSQLText(
2667                                 $table, $vars, $conds[0] + $extra_conds, $fname, $options, $join_conds
2668                         );
2669                 }
2670
2671                 // Otherwise, we need to pull out the order and limit to apply after
2672                 // the union. Then build the SQL queries for each set of conditions in
2673                 // $conds. Then union them together (using UNION ALL, because the
2674                 // product *should* already be distinct).
2675                 $orderBy = $this->makeOrderBy( $options );
2676                 $limit = isset( $options['LIMIT'] ) ? $options['LIMIT'] : null;
2677                 $offset = isset( $options['OFFSET'] ) ? $options['OFFSET'] : false;
2678                 $all = empty( $options['NOTALL'] ) && !in_array( 'NOTALL', $options );
2679                 if ( !$this->unionSupportsOrderAndLimit() ) {
2680                         unset( $options['ORDER BY'], $options['LIMIT'], $options['OFFSET'] );
2681                 } else {
2682                         if ( array_key_exists( 'INNER ORDER BY', $options ) ) {
2683                                 $options['ORDER BY'] = $options['INNER ORDER BY'];
2684                         }
2685                         if ( $limit !== null && is_numeric( $offset ) && $offset != 0 ) {
2686                                 // We need to increase the limit by the offset rather than
2687                                 // using the offset directly, otherwise it'll skip incorrectly
2688                                 // in the subqueries.
2689                                 $options['LIMIT'] = $limit + $offset;
2690                                 unset( $options['OFFSET'] );
2691                         }
2692                 }
2693
2694                 $sqls = [];
2695                 foreach ( $conds as $cond ) {
2696                         $sqls[] = $this->selectSQLText(
2697                                 $table, $vars, $cond + $extra_conds, $fname, $options, $join_conds
2698                         );
2699                 }
2700                 $sql = $this->unionQueries( $sqls, $all ) . $orderBy;
2701                 if ( $limit !== null ) {
2702                         $sql = $this->limitResult( $sql, $limit, $offset );
2703                 }
2704
2705                 return $sql;
2706         }
2707
2708         public function conditional( $cond, $trueVal, $falseVal ) {
2709                 if ( is_array( $cond ) ) {
2710                         $cond = $this->makeList( $cond, self::LIST_AND );
2711                 }
2712
2713                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2714         }
2715
2716         public function strreplace( $orig, $old, $new ) {
2717                 return "REPLACE({$orig}, {$old}, {$new})";
2718         }
2719
2720         public function getServerUptime() {
2721                 return 0;
2722         }
2723
2724         public function wasDeadlock() {
2725                 return false;
2726         }
2727
2728         public function wasLockTimeout() {
2729                 return false;
2730         }
2731
2732         public function wasErrorReissuable() {
2733                 return false;
2734         }
2735
2736         public function wasReadOnlyError() {
2737                 return false;
2738         }
2739
2740         /**
2741          * Do not use this method outside of Database/DBError classes
2742          *
2743          * @param int|string $errno
2744          * @return bool Whether the given query error was a connection drop
2745          */
2746         public function wasConnectionError( $errno ) {
2747                 return false;
2748         }
2749
2750         public function deadlockLoop() {
2751                 $args = func_get_args();
2752                 $function = array_shift( $args );
2753                 $tries = self::DEADLOCK_TRIES;
2754
2755                 $this->begin( __METHOD__ );
2756
2757                 $retVal = null;
2758                 /** @var Exception $e */
2759                 $e = null;
2760                 do {
2761                         try {
2762                                 $retVal = call_user_func_array( $function, $args );
2763                                 break;
2764                         } catch ( DBQueryError $e ) {
2765                                 if ( $this->wasDeadlock() ) {
2766                                         // Retry after a randomized delay
2767                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2768                                 } else {
2769                                         // Throw the error back up
2770                                         throw $e;
2771                                 }
2772                         }
2773                 } while ( --$tries > 0 );
2774
2775                 if ( $tries <= 0 ) {
2776                         // Too many deadlocks; give up
2777                         $this->rollback( __METHOD__ );
2778                         throw $e;
2779                 } else {
2780                         $this->commit( __METHOD__ );
2781
2782                         return $retVal;
2783                 }
2784         }
2785
2786         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2787                 # Real waits are implemented in the subclass.
2788                 return 0;
2789         }
2790
2791         public function getReplicaPos() {
2792                 # Stub
2793                 return false;
2794         }
2795
2796         public function getMasterPos() {
2797                 # Stub
2798                 return false;
2799         }
2800
2801         public function serverIsReadOnly() {
2802                 return false;
2803         }
2804
2805         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2806                 if ( !$this->trxLevel ) {
2807                         throw new DBUnexpectedError( $this, "No transaction is active." );
2808                 }
2809                 $this->trxEndCallbacks[] = [ $callback, $fname ];
2810         }
2811
2812         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2813                 $this->trxIdleCallbacks[] = [ $callback, $fname ];
2814                 if ( !$this->trxLevel ) {
2815                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2816                 }
2817         }
2818
2819         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2820                 if ( $this->trxLevel || $this->getFlag( self::DBO_TRX ) ) {
2821                         // As long as DBO_TRX is set, writes will accumulate until the load balancer issues
2822                         // an implicit commit of all peer databases. This is true even if a transaction has
2823                         // not yet been triggered by writes; make sure $callback runs *after* any such writes.
2824                         $this->trxPreCommitCallbacks[] = [ $callback, $fname ];
2825                 } else {
2826                         // No transaction is active nor will start implicitly, so make one for this callback
2827                         $this->startAtomic( __METHOD__ );
2828                         try {
2829                                 call_user_func( $callback );
2830                                 $this->endAtomic( __METHOD__ );
2831                         } catch ( Exception $e ) {
2832                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2833                                 throw $e;
2834                         }
2835                 }
2836         }
2837
2838         final public function setTransactionListener( $name, callable $callback = null ) {
2839                 if ( $callback ) {
2840                         $this->trxRecurringCallbacks[$name] = $callback;
2841                 } else {
2842                         unset( $this->trxRecurringCallbacks[$name] );
2843                 }
2844         }
2845
2846         /**
2847          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2848          *
2849          * This method should not be used outside of Database/LoadBalancer
2850          *
2851          * @param bool $suppress
2852          * @since 1.28
2853          */
2854         final public function setTrxEndCallbackSuppression( $suppress ) {
2855                 $this->trxEndCallbacksSuppressed = $suppress;
2856         }
2857
2858         /**
2859          * Actually run and consume any "on transaction idle/resolution" callbacks.
2860          *
2861          * This method should not be used outside of Database/LoadBalancer
2862          *
2863          * @param int $trigger IDatabase::TRIGGER_* constant
2864          * @since 1.20
2865          * @throws Exception
2866          */
2867         public function runOnTransactionIdleCallbacks( $trigger ) {
2868                 if ( $this->trxEndCallbacksSuppressed ) {
2869                         return;
2870                 }
2871
2872                 $autoTrx = $this->getFlag( self::DBO_TRX ); // automatic begin() enabled?
2873                 /** @var Exception $e */
2874                 $e = null; // first exception
2875                 do { // callbacks may add callbacks :)
2876                         $callbacks = array_merge(
2877                                 $this->trxIdleCallbacks,
2878                                 $this->trxEndCallbacks // include "transaction resolution" callbacks
2879                         );
2880                         $this->trxIdleCallbacks = []; // consumed (and recursion guard)
2881                         $this->trxEndCallbacks = []; // consumed (recursion guard)
2882                         foreach ( $callbacks as $callback ) {
2883                                 try {
2884                                         list( $phpCallback ) = $callback;
2885                                         $this->clearFlag( self::DBO_TRX ); // make each query its own transaction
2886                                         call_user_func_array( $phpCallback, [ $trigger ] );
2887                                         if ( $autoTrx ) {
2888                                                 $this->setFlag( self::DBO_TRX ); // restore automatic begin()
2889                                         } else {
2890                                                 $this->clearFlag( self::DBO_TRX ); // restore auto-commit
2891                                         }
2892                                 } catch ( Exception $ex ) {
2893                                         call_user_func( $this->errorLogger, $ex );
2894                                         $e = $e ?: $ex;
2895                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2896                                         // their transactions are ended so other callbacks don't fail
2897                                         if ( $this->trxLevel() ) {
2898                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2899                                         }
2900                                 }
2901                         }
2902                 } while ( count( $this->trxIdleCallbacks ) );
2903
2904                 if ( $e instanceof Exception ) {
2905                         throw $e; // re-throw any first exception
2906                 }
2907         }
2908
2909         /**
2910          * Actually run and consume any "on transaction pre-commit" callbacks.
2911          *
2912          * This method should not be used outside of Database/LoadBalancer
2913          *
2914          * @since 1.22
2915          * @throws Exception
2916          */
2917         public function runOnTransactionPreCommitCallbacks() {
2918                 $e = null; // first exception
2919                 do { // callbacks may add callbacks :)
2920                         $callbacks = $this->trxPreCommitCallbacks;
2921                         $this->trxPreCommitCallbacks = []; // consumed (and recursion guard)
2922                         foreach ( $callbacks as $callback ) {
2923                                 try {
2924                                         list( $phpCallback ) = $callback;
2925                                         call_user_func( $phpCallback );
2926                                 } catch ( Exception $ex ) {
2927                                         call_user_func( $this->errorLogger, $ex );
2928                                         $e = $e ?: $ex;
2929                                 }
2930                         }
2931                 } while ( count( $this->trxPreCommitCallbacks ) );
2932
2933                 if ( $e instanceof Exception ) {
2934                         throw $e; // re-throw any first exception
2935                 }
2936         }
2937
2938         /**
2939          * Actually run any "transaction listener" callbacks.
2940          *
2941          * This method should not be used outside of Database/LoadBalancer
2942          *
2943          * @param int $trigger IDatabase::TRIGGER_* constant
2944          * @throws Exception
2945          * @since 1.20
2946          */
2947         public function runTransactionListenerCallbacks( $trigger ) {
2948                 if ( $this->trxEndCallbacksSuppressed ) {
2949                         return;
2950                 }
2951
2952                 /** @var Exception $e */
2953                 $e = null; // first exception
2954
2955                 foreach ( $this->trxRecurringCallbacks as $phpCallback ) {
2956                         try {
2957                                 $phpCallback( $trigger, $this );
2958                         } catch ( Exception $ex ) {
2959                                 call_user_func( $this->errorLogger, $ex );
2960                                 $e = $e ?: $ex;
2961                         }
2962                 }
2963
2964                 if ( $e instanceof Exception ) {
2965                         throw $e; // re-throw any first exception
2966                 }
2967         }
2968
2969         final public function startAtomic( $fname = __METHOD__ ) {
2970                 if ( !$this->trxLevel ) {
2971                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2972                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2973                         // in all changes being in one transaction to keep requests transactional.
2974                         if ( !$this->getFlag( self::DBO_TRX ) ) {
2975                                 $this->trxAutomaticAtomic = true;
2976                         }
2977                 }
2978
2979                 $this->trxAtomicLevels[] = $fname;
2980         }
2981
2982         final public function endAtomic( $fname = __METHOD__ ) {
2983                 if ( !$this->trxLevel ) {
2984                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2985                 }
2986                 if ( !$this->trxAtomicLevels ||
2987                         array_pop( $this->trxAtomicLevels ) !== $fname
2988                 ) {
2989                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2990                 }
2991
2992                 if ( !$this->trxAtomicLevels && $this->trxAutomaticAtomic ) {
2993                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2994                 }
2995         }
2996
2997         final public function doAtomicSection( $fname, callable $callback ) {
2998                 $this->startAtomic( $fname );
2999                 try {
3000                         $res = call_user_func_array( $callback, [ $this, $fname ] );
3001                 } catch ( Exception $e ) {
3002                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
3003                         throw $e;
3004                 }
3005                 $this->endAtomic( $fname );
3006
3007                 return $res;
3008         }
3009
3010         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
3011                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
3012                 if ( $this->trxLevel ) {
3013                         if ( $this->trxAtomicLevels ) {
3014                                 $levels = implode( ', ', $this->trxAtomicLevels );
3015                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
3016                                 throw new DBUnexpectedError( $this, $msg );
3017                         } elseif ( !$this->trxAutomatic ) {
3018                                 $msg = "$fname: Explicit transaction already active (from {$this->trxFname}).";
3019                                 throw new DBUnexpectedError( $this, $msg );
3020                         } else {
3021                                 // @TODO: make this an exception at some point
3022                                 $msg = "$fname: Implicit transaction already active (from {$this->trxFname}).";
3023                                 $this->queryLogger->error( $msg );
3024                                 return; // join the main transaction set
3025                         }
3026                 } elseif ( $this->getFlag( self::DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
3027                         // @TODO: make this an exception at some point
3028                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
3029                         $this->queryLogger->error( $msg );
3030                         return; // let any writes be in the main transaction
3031                 }
3032
3033                 // Avoid fatals if close() was called
3034                 $this->assertOpen();
3035
3036                 $this->doBegin( $fname );
3037                 $this->trxTimestamp = microtime( true );
3038                 $this->trxFname = $fname;
3039                 $this->trxDoneWrites = false;
3040                 $this->trxAutomaticAtomic = false;
3041                 $this->trxAtomicLevels = [];
3042                 $this->trxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
3043                 $this->trxWriteDuration = 0.0;
3044                 $this->trxWriteQueryCount = 0;
3045                 $this->trxWriteAffectedRows = 0;
3046                 $this->trxWriteAdjDuration = 0.0;
3047                 $this->trxWriteAdjQueryCount = 0;
3048                 $this->trxWriteCallers = [];
3049                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
3050                 // Get an estimate of the replica DB lag before then, treating estimate staleness
3051                 // as lag itself just to be safe
3052                 $status = $this->getApproximateLagStatus();
3053                 $this->trxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
3054                 // T147697: make explicitTrxActive() return true until begin() finishes. This way, no
3055                 // caller will think its OK to muck around with the transaction just because startAtomic()
3056                 // has not yet completed (e.g. setting trxAtomicLevels).
3057                 $this->trxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
3058         }
3059
3060         /**
3061          * Issues the BEGIN command to the database server.
3062          *
3063          * @see Database::begin()
3064          * @param string $fname
3065          */
3066         protected function doBegin( $fname ) {
3067                 $this->query( 'BEGIN', $fname );
3068                 $this->trxLevel = 1;
3069         }
3070
3071         final public function commit( $fname = __METHOD__, $flush = '' ) {
3072                 if ( $this->trxLevel && $this->trxAtomicLevels ) {
3073                         // There are still atomic sections open. This cannot be ignored
3074                         $levels = implode( ', ', $this->trxAtomicLevels );
3075                         throw new DBUnexpectedError(
3076                                 $this,
3077                                 "$fname: Got COMMIT while atomic sections $levels are still open."
3078                         );
3079                 }
3080
3081                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3082                         if ( !$this->trxLevel ) {
3083                                 return; // nothing to do
3084                         } elseif ( !$this->trxAutomatic ) {
3085                                 throw new DBUnexpectedError(
3086                                         $this,
3087                                         "$fname: Flushing an explicit transaction, getting out of sync."
3088                                 );
3089                         }
3090                 } else {
3091                         if ( !$this->trxLevel ) {
3092                                 $this->queryLogger->error(
3093                                         "$fname: No transaction to commit, something got out of sync." );
3094                                 return; // nothing to do
3095                         } elseif ( $this->trxAutomatic ) {
3096                                 // @TODO: make this an exception at some point
3097                                 $msg = "$fname: Explicit commit of implicit transaction.";
3098                                 $this->queryLogger->error( $msg );
3099                                 return; // wait for the main transaction set commit round
3100                         }
3101                 }
3102
3103                 // Avoid fatals if close() was called
3104                 $this->assertOpen();
3105
3106                 $this->runOnTransactionPreCommitCallbacks();
3107                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3108                 $this->doCommit( $fname );
3109                 if ( $this->trxDoneWrites ) {
3110                         $this->lastWriteTime = microtime( true );
3111                         $this->trxProfiler->transactionWritingOut(
3112                                 $this->server,
3113                                 $this->dbName,
3114                                 $this->trxShortId,
3115                                 $writeTime,
3116                                 $this->trxWriteAffectedRows
3117                         );
3118                 }
3119
3120                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3121                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3122         }
3123
3124         /**
3125          * Issues the COMMIT command to the database server.
3126          *
3127          * @see Database::commit()
3128          * @param string $fname
3129          */
3130         protected function doCommit( $fname ) {
3131                 if ( $this->trxLevel ) {
3132                         $this->query( 'COMMIT', $fname );
3133                         $this->trxLevel = 0;
3134                 }
3135         }
3136
3137         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3138                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3139                         if ( !$this->trxLevel ) {
3140                                 return; // nothing to do
3141                         }
3142                 } else {
3143                         if ( !$this->trxLevel ) {
3144                                 $this->queryLogger->error(
3145                                         "$fname: No transaction to rollback, something got out of sync." );
3146                                 return; // nothing to do
3147                         } elseif ( $this->getFlag( self::DBO_TRX ) ) {
3148                                 throw new DBUnexpectedError(
3149                                         $this,
3150                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3151                                 );
3152                         }
3153                 }
3154
3155                 // Avoid fatals if close() was called
3156                 $this->assertOpen();
3157
3158                 $this->doRollback( $fname );
3159                 $this->trxAtomicLevels = [];
3160                 if ( $this->trxDoneWrites ) {
3161                         $this->trxProfiler->transactionWritingOut(
3162                                 $this->server,
3163                                 $this->dbName,
3164                                 $this->trxShortId
3165                         );
3166                 }
3167
3168                 $this->trxIdleCallbacks = []; // clear
3169                 $this->trxPreCommitCallbacks = []; // clear
3170                 try {
3171                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3172                 } catch ( Exception $e ) {
3173                         // already logged; finish and let LoadBalancer move on during mass-rollback
3174                 }
3175                 try {
3176                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3177                 } catch ( Exception $e ) {
3178                         // already logged; let LoadBalancer move on during mass-rollback
3179                 }
3180
3181                 $this->affectedRowCount = 0; // for the sake of consistency
3182         }
3183
3184         /**
3185          * Issues the ROLLBACK command to the database server.
3186          *
3187          * @see Database::rollback()
3188          * @param string $fname
3189          */
3190         protected function doRollback( $fname ) {
3191                 if ( $this->trxLevel ) {
3192                         # Disconnects cause rollback anyway, so ignore those errors
3193                         $ignoreErrors = true;
3194                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3195                         $this->trxLevel = 0;
3196                 }
3197         }
3198
3199         public function flushSnapshot( $fname = __METHOD__ ) {
3200                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3201                         // This only flushes transactions to clear snapshots, not to write data
3202                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3203                         throw new DBUnexpectedError(
3204                                 $this,
3205                                 "$fname: Cannot flush snapshot because writes are pending ($fnames)."
3206                         );
3207                 }
3208
3209                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3210         }
3211
3212         public function explicitTrxActive() {
3213                 return $this->trxLevel && ( $this->trxAtomicLevels || !$this->trxAutomatic );
3214         }
3215
3216         public function duplicateTableStructure(
3217                 $oldName, $newName, $temporary = false, $fname = __METHOD__
3218         ) {
3219                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3220         }
3221
3222         public function listTables( $prefix = null, $fname = __METHOD__ ) {
3223                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3224         }
3225
3226         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3227                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
3228         }
3229
3230         public function timestamp( $ts = 0 ) {
3231                 $t = new ConvertibleTimestamp( $ts );
3232                 // Let errors bubble up to avoid putting garbage in the DB
3233                 return $t->getTimestamp( TS_MW );
3234         }
3235
3236         public function timestampOrNull( $ts = null ) {
3237                 if ( is_null( $ts ) ) {
3238                         return null;
3239                 } else {
3240                         return $this->timestamp( $ts );
3241                 }
3242         }
3243
3244         public function affectedRows() {
3245                 return ( $this->affectedRowCount === null )
3246                         ? $this->fetchAffectedRowCount() // default to driver value
3247                         : $this->affectedRowCount;
3248         }
3249
3250         /**
3251          * @return int Number of retrieved rows according to the driver
3252          */
3253         abstract protected function fetchAffectedRowCount();
3254
3255         /**
3256          * Take the result from a query, and wrap it in a ResultWrapper if
3257          * necessary. Boolean values are passed through as is, to indicate success
3258          * of write queries or failure.
3259          *
3260          * Once upon a time, Database::query() returned a bare MySQL result
3261          * resource, and it was necessary to call this function to convert it to
3262          * a wrapper. Nowadays, raw database objects are never exposed to external
3263          * callers, so this is unnecessary in external code.
3264          *
3265          * @param bool|ResultWrapper|resource|object $result
3266          * @return bool|ResultWrapper
3267          */
3268         protected function resultObject( $result ) {
3269                 if ( !$result ) {
3270                         return false;
3271                 } elseif ( $result instanceof ResultWrapper ) {
3272                         return $result;
3273                 } elseif ( $result === true ) {
3274                         // Successful write query
3275                         return $result;
3276                 } else {
3277                         return new ResultWrapper( $this, $result );
3278                 }
3279         }
3280
3281         public function ping( &$rtt = null ) {
3282                 // Avoid hitting the server if it was hit recently
3283                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3284                         if ( !func_num_args() || $this->rttEstimate > 0 ) {
3285                                 $rtt = $this->rttEstimate;
3286                                 return true; // don't care about $rtt
3287                         }
3288                 }
3289
3290                 // This will reconnect if possible or return false if not
3291                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
3292                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3293                 $this->restoreFlags( self::RESTORE_PRIOR );
3294
3295                 if ( $ok ) {
3296                         $rtt = $this->rttEstimate;
3297                 }
3298
3299                 return $ok;
3300         }
3301
3302         /**
3303          * Close existing database connection and open a new connection
3304          *
3305          * @return bool True if new connection is opened successfully, false if error
3306          */
3307         protected function reconnect() {
3308                 $this->closeConnection();
3309                 $this->opened = false;
3310                 $this->conn = false;
3311                 try {
3312                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3313                         $this->lastPing = microtime( true );
3314                         $ok = true;
3315                 } catch ( DBConnectionError $e ) {
3316                         $ok = false;
3317                 }
3318
3319                 return $ok;
3320         }
3321
3322         public function getSessionLagStatus() {
3323                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3324         }
3325
3326         /**
3327          * Get the replica DB lag when the current transaction started
3328          *
3329          * This is useful when transactions might use snapshot isolation
3330          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3331          * is this lag plus transaction duration. If they don't, it is still
3332          * safe to be pessimistic. This returns null if there is no transaction.
3333          *
3334          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3335          * @since 1.27
3336          */
3337         protected function getTransactionLagStatus() {
3338                 return $this->trxLevel
3339                         ? [ 'lag' => $this->trxReplicaLag, 'since' => $this->trxTimestamp() ]
3340                         : null;
3341         }
3342
3343         /**
3344          * Get a replica DB lag estimate for this server
3345          *
3346          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3347          * @since 1.27
3348          */
3349         protected function getApproximateLagStatus() {
3350                 return [
3351                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3352                         'since' => microtime( true )
3353                 ];
3354         }
3355
3356         /**
3357          * Merge the result of getSessionLagStatus() for several DBs
3358          * using the most pessimistic values to estimate the lag of
3359          * any data derived from them in combination
3360          *
3361          * This is information is useful for caching modules
3362          *
3363          * @see WANObjectCache::set()
3364          * @see WANObjectCache::getWithSetCallback()
3365          *
3366          * @param IDatabase $db1
3367          * @param IDatabase $db2 [optional]
3368          * @return array Map of values:
3369          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3370          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3371          *   - pending: whether any of the DBs have uncommitted changes
3372          * @throws DBError
3373          * @since 1.27
3374          */
3375         public static function getCacheSetOptions( IDatabase $db1, IDatabase $db2 = null ) {
3376                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3377                 foreach ( func_get_args() as $db ) {
3378                         /** @var IDatabase $db */
3379                         $status = $db->getSessionLagStatus();
3380                         if ( $status['lag'] === false ) {
3381                                 $res['lag'] = false;
3382                         } elseif ( $res['lag'] !== false ) {
3383                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3384                         }
3385                         $res['since'] = min( $res['since'], $status['since'] );
3386                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3387                 }
3388
3389                 return $res;
3390         }
3391
3392         public function getLag() {
3393                 return 0;
3394         }
3395
3396         public function maxListLen() {
3397                 return 0;
3398         }
3399
3400         public function encodeBlob( $b ) {
3401                 return $b;
3402         }
3403
3404         public function decodeBlob( $b ) {
3405                 if ( $b instanceof Blob ) {
3406                         $b = $b->fetch();
3407                 }
3408                 return $b;
3409         }
3410
3411         public function setSessionOptions( array $options ) {
3412         }
3413
3414         public function sourceFile(
3415                 $filename,
3416                 callable $lineCallback = null,
3417                 callable $resultCallback = null,
3418                 $fname = false,
3419                 callable $inputCallback = null
3420         ) {
3421                 Wikimedia\suppressWarnings();
3422                 $fp = fopen( $filename, 'r' );
3423                 Wikimedia\restoreWarnings();
3424
3425                 if ( false === $fp ) {
3426                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3427                 }
3428
3429                 if ( !$fname ) {
3430                         $fname = __METHOD__ . "( $filename )";
3431                 }
3432
3433                 try {
3434                         $error = $this->sourceStream(
3435                                 $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3436                 } catch ( Exception $e ) {
3437                         fclose( $fp );
3438                         throw $e;
3439                 }
3440
3441                 fclose( $fp );
3442
3443                 return $error;
3444         }
3445
3446         public function setSchemaVars( $vars ) {
3447                 $this->schemaVars = $vars;
3448         }
3449
3450         public function sourceStream(
3451                 $fp,
3452                 callable $lineCallback = null,
3453                 callable $resultCallback = null,
3454                 $fname = __METHOD__,
3455                 callable $inputCallback = null
3456         ) {
3457                 $delimiterReset = new ScopedCallback(
3458                         function ( $delimiter ) {
3459                                 $this->delimiter = $delimiter;
3460                         },
3461                         [ $this->delimiter ]
3462                 );
3463                 $cmd = '';
3464
3465                 while ( !feof( $fp ) ) {
3466                         if ( $lineCallback ) {
3467                                 call_user_func( $lineCallback );
3468                         }
3469
3470                         $line = trim( fgets( $fp ) );
3471
3472                         if ( $line == '' ) {
3473                                 continue;
3474                         }
3475
3476                         if ( '-' == $line[0] && '-' == $line[1] ) {
3477                                 continue;
3478                         }
3479
3480                         if ( $cmd != '' ) {
3481                                 $cmd .= ' ';
3482                         }
3483
3484                         $done = $this->streamStatementEnd( $cmd, $line );
3485
3486                         $cmd .= "$line\n";
3487
3488                         if ( $done || feof( $fp ) ) {
3489                                 $cmd = $this->replaceVars( $cmd );
3490
3491                                 if ( $inputCallback ) {
3492                                         $callbackResult = call_user_func( $inputCallback, $cmd );
3493
3494                                         if ( is_string( $callbackResult ) || !$callbackResult ) {
3495                                                 $cmd = $callbackResult;
3496                                         }
3497                                 }
3498
3499                                 if ( $cmd ) {
3500                                         $res = $this->query( $cmd, $fname );
3501
3502                                         if ( $resultCallback ) {
3503                                                 call_user_func( $resultCallback, $res, $this );
3504                                         }
3505
3506                                         if ( false === $res ) {
3507                                                 $err = $this->lastError();
3508
3509                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3510                                         }
3511                                 }
3512                                 $cmd = '';
3513                         }
3514                 }
3515
3516                 ScopedCallback::consume( $delimiterReset );
3517                 return true;
3518         }
3519
3520         /**
3521          * Called by sourceStream() to check if we've reached a statement end
3522          *
3523          * @param string &$sql SQL assembled so far
3524          * @param string &$newLine New line about to be added to $sql
3525          * @return bool Whether $newLine contains end of the statement
3526          */
3527         public function streamStatementEnd( &$sql, &$newLine ) {
3528                 if ( $this->delimiter ) {
3529                         $prev = $newLine;
3530                         $newLine = preg_replace(
3531                                 '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3532                         if ( $newLine != $prev ) {
3533                                 return true;
3534                         }
3535                 }
3536
3537                 return false;
3538         }
3539
3540         /**
3541          * Database independent variable replacement. Replaces a set of variables
3542          * in an SQL statement with their contents as given by $this->getSchemaVars().
3543          *
3544          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3545          *
3546          * - '{$var}' should be used for text and is passed through the database's
3547          *   addQuotes method.
3548          * - `{$var}` should be used for identifiers (e.g. table and database names).
3549          *   It is passed through the database's addIdentifierQuotes method which
3550          *   can be overridden if the database uses something other than backticks.
3551          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3552          *   database's tableName method.
3553          * - / *i* / passes the name that follows through the database's indexName method.
3554          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3555          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3556          *
3557          * @param string $ins SQL statement to replace variables in
3558          * @return string The new SQL statement with variables replaced
3559          */
3560         protected function replaceVars( $ins ) {
3561                 $vars = $this->getSchemaVars();
3562                 return preg_replace_callback(
3563                         '!
3564                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3565                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3566                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3567                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3568                         !x',
3569                         function ( $m ) use ( $vars ) {
3570                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3571                                 // check for both nonexistent keys *and* the empty string.
3572                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3573                                         if ( $m[1] === 'i' ) {
3574                                                 return $this->indexName( $m[2] );
3575                                         } else {
3576                                                 return $this->tableName( $m[2] );
3577                                         }
3578                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3579                                         return $this->addQuotes( $vars[$m[3]] );
3580                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3581                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3582                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3583                                         return $vars[$m[5]];
3584                                 } else {
3585                                         return $m[0];
3586                                 }
3587                         },
3588                         $ins
3589                 );
3590         }
3591
3592         /**
3593          * Get schema variables. If none have been set via setSchemaVars(), then
3594          * use some defaults from the current object.
3595          *
3596          * @return array
3597          */
3598         protected function getSchemaVars() {
3599                 if ( $this->schemaVars ) {
3600                         return $this->schemaVars;
3601                 } else {
3602                         return $this->getDefaultSchemaVars();
3603                 }
3604         }
3605
3606         /**
3607          * Get schema variables to use if none have been set via setSchemaVars().
3608          *
3609          * Override this in derived classes to provide variables for tables.sql
3610          * and SQL patch files.
3611          *
3612          * @return array
3613          */
3614         protected function getDefaultSchemaVars() {
3615                 return [];
3616         }
3617
3618         public function lockIsFree( $lockName, $method ) {
3619                 // RDBMs methods for checking named locks may or may not count this thread itself.
3620                 // In MySQL, IS_FREE_LOCK() returns 0 if the thread already has the lock. This is
3621                 // the behavior choosen by the interface for this method.
3622                 return !isset( $this->namedLocksHeld[$lockName] );
3623         }
3624
3625         public function lock( $lockName, $method, $timeout = 5 ) {
3626                 $this->namedLocksHeld[$lockName] = 1;
3627
3628                 return true;
3629         }
3630
3631         public function unlock( $lockName, $method ) {
3632                 unset( $this->namedLocksHeld[$lockName] );
3633
3634                 return true;
3635         }
3636
3637         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3638                 if ( $this->writesOrCallbacksPending() ) {
3639                         // This only flushes transactions to clear snapshots, not to write data
3640                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3641                         throw new DBUnexpectedError(
3642                                 $this,
3643                                 "$fname: Cannot flush pre-lock snapshot because writes are pending ($fnames)."
3644                         );
3645                 }
3646
3647                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3648                         return null;
3649                 }
3650
3651                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3652                         if ( $this->trxLevel() ) {
3653                                 // There is a good chance an exception was thrown, causing any early return
3654                                 // from the caller. Let any error handler get a chance to issue rollback().
3655                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3656                                 $this->onTransactionResolution(
3657                                         function () use ( $lockKey, $fname ) {
3658                                                 $this->unlock( $lockKey, $fname );
3659                                         },
3660                                         $fname
3661                                 );
3662                         } else {
3663                                 $this->unlock( $lockKey, $fname );
3664                         }
3665                 } );
3666
3667                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3668
3669                 return $unlocker;
3670         }
3671
3672         public function namedLocksEnqueue() {
3673                 return false;
3674         }
3675
3676         public function tableLocksHaveTransactionScope() {
3677                 return true;
3678         }
3679
3680         final public function lockTables( array $read, array $write, $method ) {
3681                 if ( $this->writesOrCallbacksPending() ) {
3682                         throw new DBUnexpectedError( $this, "Transaction writes or callbacks still pending." );
3683                 }
3684
3685                 if ( $this->tableLocksHaveTransactionScope() ) {
3686                         $this->startAtomic( $method );
3687                 }
3688
3689                 return $this->doLockTables( $read, $write, $method );
3690         }
3691
3692         /**
3693          * Helper function for lockTables() that handles the actual table locking
3694          *
3695          * @param array $read Array of tables to lock for read access
3696          * @param array $write Array of tables to lock for write access
3697          * @param string $method Name of caller
3698          * @return true
3699          */
3700         protected function doLockTables( array $read, array $write, $method ) {
3701                 return true;
3702         }
3703
3704         final public function unlockTables( $method ) {
3705                 if ( $this->tableLocksHaveTransactionScope() ) {
3706                         $this->endAtomic( $method );
3707
3708                         return true; // locks released on COMMIT/ROLLBACK
3709                 }
3710
3711                 return $this->doUnlockTables( $method );
3712         }
3713
3714         /**
3715          * Helper function for unlockTables() that handles the actual table unlocking
3716          *
3717          * @param string $method Name of caller
3718          * @return true
3719          */
3720         protected function doUnlockTables( $method ) {
3721                 return true;
3722         }
3723
3724         /**
3725          * Delete a table
3726          * @param string $tableName
3727          * @param string $fName
3728          * @return bool|ResultWrapper
3729          * @since 1.18
3730          */
3731         public function dropTable( $tableName, $fName = __METHOD__ ) {
3732                 if ( !$this->tableExists( $tableName, $fName ) ) {
3733                         return false;
3734                 }
3735                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3736
3737                 return $this->query( $sql, $fName );
3738         }
3739
3740         public function getInfinity() {
3741                 return 'infinity';
3742         }
3743
3744         public function encodeExpiry( $expiry ) {
3745                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3746                         ? $this->getInfinity()
3747                         : $this->timestamp( $expiry );
3748         }
3749
3750         public function decodeExpiry( $expiry, $format = TS_MW ) {
3751                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3752                         return 'infinity';
3753                 }
3754
3755                 return ConvertibleTimestamp::convert( $format, $expiry );
3756         }
3757
3758         public function setBigSelects( $value = true ) {
3759                 // no-op
3760         }
3761
3762         public function isReadOnly() {
3763                 return ( $this->getReadOnlyReason() !== false );
3764         }
3765
3766         /**
3767          * @return string|bool Reason this DB is read-only or false if it is not
3768          */
3769         protected function getReadOnlyReason() {
3770                 $reason = $this->getLBInfo( 'readOnlyReason' );
3771
3772                 return is_string( $reason ) ? $reason : false;
3773         }
3774
3775         public function setTableAliases( array $aliases ) {
3776                 $this->tableAliases = $aliases;
3777         }
3778
3779         /**
3780          * @return bool Whether a DB user is required to access the DB
3781          * @since 1.28
3782          */
3783         protected function requiresDatabaseUser() {
3784                 return true;
3785         }
3786
3787         /**
3788          * Get the underlying binding connection handle
3789          *
3790          * Makes sure the connection resource is set (disconnects and ping() failure can unset it).
3791          * This catches broken callers than catch and ignore disconnection exceptions.
3792          * Unlike checking isOpen(), this is safe to call inside of open().
3793          *
3794          * @return resource|object
3795          * @throws DBUnexpectedError
3796          * @since 1.26
3797          */
3798         protected function getBindingHandle() {
3799                 if ( !$this->conn ) {
3800                         throw new DBUnexpectedError(
3801                                 $this,
3802                                 'DB connection was already closed or the connection dropped.'
3803                         );
3804                 }
3805
3806                 return $this->conn;
3807         }
3808
3809         /**
3810          * @since 1.19
3811          * @return string
3812          */
3813         public function __toString() {
3814                 return (string)$this->conn;
3815         }
3816
3817         /**
3818          * Make sure that copies do not share the same client binding handle
3819          * @throws DBConnectionError
3820          */
3821         public function __clone() {
3822                 $this->connLogger->warning(
3823                         "Cloning " . static::class . " is not recomended; forking connection:\n" .
3824                         ( new RuntimeException() )->getTraceAsString()
3825                 );
3826
3827                 if ( $this->isOpen() ) {
3828                         // Open a new connection resource without messing with the old one
3829                         $this->opened = false;
3830                         $this->conn = false;
3831                         $this->trxEndCallbacks = []; // don't copy
3832                         $this->handleSessionLoss(); // no trx or locks anymore
3833                         $this->open( $this->server, $this->user, $this->password, $this->dbName );
3834                         $this->lastPing = microtime( true );
3835                 }
3836         }
3837
3838         /**
3839          * Called by serialize. Throw an exception when DB connection is serialized.
3840          * This causes problems on some database engines because the connection is
3841          * not restored on unserialize.
3842          */
3843         public function __sleep() {
3844                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3845                         'the connection is not restored on wakeup.' );
3846         }
3847
3848         /**
3849          * Run a few simple sanity checks and close dangling connections
3850          */
3851         public function __destruct() {
3852                 if ( $this->trxLevel && $this->trxDoneWrites ) {
3853                         trigger_error( "Uncommitted DB writes (transaction from {$this->trxFname})." );
3854                 }
3855
3856                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3857                 if ( $danglingWriters ) {
3858                         $fnames = implode( ', ', $danglingWriters );
3859                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3860                 }
3861
3862                 if ( $this->conn ) {
3863                         // Avoid connection leaks for sanity. Normally, resources close at script completion.
3864                         // The connection might already be closed in zend/hhvm by now, so suppress warnings.
3865                         Wikimedia\suppressWarnings();
3866                         $this->closeConnection();
3867                         Wikimedia\restoreWarnings();
3868                         $this->conn = false;
3869                         $this->opened = false;
3870                 }
3871         }
3872 }
3873
3874 class_alias( Database::class, 'DatabaseBase' ); // b/c for old name
3875 class_alias( Database::class, 'Database' ); // b/c global alias