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 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28
  29 /**
  30  * Database abstraction object
  31  * @ingroup Database
  32  */
  33 abstract class Database implements IDatabase, LoggerAwareInterface {
  34         /** Number of times to re-try an operation in case of deadlock */
  35         const DEADLOCK_TRIES = 4;
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38         /** Maximum time to wait before retry */
  39         const DEADLOCK_DELAY_MAX = 1500000;
  40
  41         /** How long before it is worth doing a dummy query to test the connection */
  42         const PING_TTL = 1.0;
  43         const PING_QUERY = 'SELECT 1 AS ping';
  44
  45         const TINY_WRITE_SEC = .010;
  46         const SLOW_WRITE_SEC = .500;
  47         const SMALL_WRITE_ROWS = 100;
  48
  49         /** @var string SQL query */
  50         protected $mLastQuery = '';
  51         /** @var bool */
  52         protected $mDoneWrites = false;
  53         /** @var string|bool */
  54         protected $mPHPError = false;
  55         /** @var string */
  56         protected $mServer;
  57         /** @var string */
  58         protected $mUser;
  59         /** @var string */
  60         protected $mPassword;
  61         /** @var string */
  62         protected $mDBname;
  63         /** @var array[] $aliases Map of (table => (dbname, schema, prefix) map) */
  64         protected $tableAliases = [];
  65         /** @var bool Whether this PHP instance is for a CLI script */
  66         protected $cliMode;
  67         /** @var string Agent name for query profiling */
  68         protected $agent;
  69
  70         /** @var BagOStuff APC cache */
  71         protected $srvCache;
  72         /** @var LoggerInterface */
  73         protected $connLogger;
  74         /** @var LoggerInterface */
  75         protected $queryLogger;
  76         /** @var callback Error logging callback */
  77         protected $errorLogger;
  78
  79         /** @var resource Database connection */
  80         protected $mConn = null;
  81         /** @var bool */
  82         protected $mOpened = false;
  83
  84         /** @var array[] List of (callable, method name) */
  85         protected $mTrxIdleCallbacks = [];
  86         /** @var array[] List of (callable, method name) */
  87         protected $mTrxPreCommitCallbacks = [];
  88         /** @var array[] List of (callable, method name) */
  89         protected $mTrxEndCallbacks = [];
  90         /** @var callable[] Map of (name => callable) */
  91         protected $mTrxRecurringCallbacks = [];
  92         /** @var bool Whether to suppress triggering of transaction end callbacks */
  93         protected $mTrxEndCallbacksSuppressed = false;
  94
  95         /** @var string */
  96         protected $mTablePrefix = '';
  97         /** @var string */
  98         protected $mSchema = '';
  99         /** @var integer */
 100         protected $mFlags;
 101         /** @var array */
 102         protected $mLBInfo = [];
 103         /** @var bool|null */
 104         protected $mDefaultBigSelects = null;
 105         /** @var array|bool */
 106         protected $mSchemaVars = false;
 107         /** @var array */
 108         protected $mSessionVars = [];
 109         /** @var array|null */
 110         protected $preparedArgs;
 111         /** @var string|bool|null Stashed value of html_errors INI setting */
 112         protected $htmlErrors;
 113         /** @var string */
 114         protected $delimiter = ';';
 115
 116         /**
 117          * Either 1 if a transaction is active or 0 otherwise.
 118          * The other Trx fields may not be meaningfull if this is 0.
 119          *
 120          * @var int
 121          */
 122         protected $mTrxLevel = 0;
 123         /**
 124          * Either a short hexidecimal string if a transaction is active or ""
 125          *
 126          * @var string
 127          * @see DatabaseBase::mTrxLevel
 128          */
 129         protected $mTrxShortId = '';
 130         /**
 131          * The UNIX time that the transaction started. Callers can assume that if
 132          * snapshot isolation is used, then the data is *at least* up to date to that
 133          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 134          *
 135          * @var float|null
 136          * @see DatabaseBase::mTrxLevel
 137          */
 138         private $mTrxTimestamp = null;
 139         /** @var float Lag estimate at the time of BEGIN */
 140         private $mTrxReplicaLag = null;
 141         /**
 142          * Remembers the function name given for starting the most recent transaction via begin().
 143          * Used to provide additional context for error reporting.
 144          *
 145          * @var string
 146          * @see DatabaseBase::mTrxLevel
 147          */
 148         private $mTrxFname = null;
 149         /**
 150          * Record if possible write queries were done in the last transaction started
 151          *
 152          * @var bool
 153          * @see DatabaseBase::mTrxLevel
 154          */
 155         private $mTrxDoneWrites = false;
 156         /**
 157          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 158          *
 159          * @var bool
 160          * @see DatabaseBase::mTrxLevel
 161          */
 162         private $mTrxAutomatic = false;
 163         /**
 164          * Array of levels of atomicity within transactions
 165          *
 166          * @var array
 167          */
 168         private $mTrxAtomicLevels = [];
 169         /**
 170          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 171          *
 172          * @var bool
 173          */
 174         private $mTrxAutomaticAtomic = false;
 175         /**
 176          * Track the write query callers of the current transaction
 177          *
 178          * @var string[]
 179          */
 180         private $mTrxWriteCallers = [];
 181         /**
 182          * @var float Seconds spent in write queries for the current transaction
 183          */
 184         private $mTrxWriteDuration = 0.0;
 185         /**
 186          * @var integer Number of write queries for the current transaction
 187          */
 188         private $mTrxWriteQueryCount = 0;
 189         /**
 190          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 191          */
 192         private $mTrxWriteAdjDuration = 0.0;
 193         /**
 194          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 195          */
 196         private $mTrxWriteAdjQueryCount = 0;
 197         /**
 198          * @var float RTT time estimate
 199          */
 200         private $mRTTEstimate = 0.0;
 201
 202         /** @var array Map of (name => 1) for locks obtained via lock() */
 203         private $mNamedLocksHeld = [];
 204
 205         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 206         private $lazyMasterHandle;
 207
 208         /**
 209          * @since 1.21
 210          * @var resource File handle for upgrade
 211          */
 212         protected $fileHandle = null;
 213
 214         /**
 215          * @since 1.22
 216          * @var string[] Process cache of VIEWs names in the database
 217          */
 218         protected $allViews = null;
 219
 220         /** @var float UNIX timestamp */
 221         protected $lastPing = 0.0;
 222
 223         /** @var int[] Prior mFlags values */
 224         private $priorFlags = [];
 225
 226         /** @var object|string Class name or object With profileIn/profileOut methods */
 227         protected $profiler;
 228         /** @var TransactionProfiler */
 229         protected $trxProfiler;
 230
 231         /**
 232          * Constructor.
 233          *
 234          * FIXME: It is possible to construct a Database object with no associated
 235          * connection object, by specifying no parameters to __construct(). This
 236          * feature is deprecated and should be removed.
 237          *
 238          * IDatabase classes should not be constructed directly in external
 239          * code. DatabaseBase::factory() should be used instead.
 240          *
 241          * @param array $params Parameters passed from DatabaseBase::factory()
 242          */
 243         function __construct( array $params ) {
 244                 $server = $params['host'];
 245                 $user = $params['user'];
 246                 $password = $params['password'];
 247                 $dbName = $params['dbname'];
 248                 $flags = $params['flags'];
 249
 250                 $this->mSchema = $params['schema'];
 251                 $this->mTablePrefix = $params['tablePrefix'];
 252
 253                 $this->cliMode = isset( $params['cliMode'] )
 254                         ? $params['cliMode']
 255                         : ( PHP_SAPI === 'cli' );
 256                 $this->agent = isset( $params['agent'] )
 257                         ? str_replace( '/', '-', $params['agent'] ) // escape for comment
 258                         : '';
 259
 260                 $this->mFlags = $flags;
 261                 if ( $this->mFlags & DBO_DEFAULT ) {
 262                         if ( $this->cliMode ) {
 263                                 $this->mFlags &= ~DBO_TRX;
 264                         } else {
 265                                 $this->mFlags |= DBO_TRX;
 266                         }
 267                 }
 268
 269                 $this->mSessionVars = $params['variables'];
 270
 271                 $this->srvCache = isset( $params['srvCache'] )
 272                         ? $params['srvCache']
 273                         : new HashBagOStuff();
 274
 275                 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
 276                 $this->trxProfiler = isset( $params['trxProfiler'] )
 277                         ? $params['trxProfiler']
 278                         : new TransactionProfiler();
 279                 $this->connLogger = isset( $params['connLogger'] )
 280                         ? $params['connLogger']
 281                         : new \Psr\Log\NullLogger();
 282                 $this->queryLogger = isset( $params['queryLogger'] )
 283                         ? $params['queryLogger']
 284                         : new \Psr\Log\NullLogger();
 285
 286                 if ( $user ) {
 287                         $this->open( $server, $user, $password, $dbName );
 288                 }
 289         }
 290
 291         /**
 292          * Given a DB type, construct the name of the appropriate child class of
 293          * IDatabase. This is designed to replace all of the manual stuff like:
 294          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 295          * as well as validate against the canonical list of DB types we have
 296          *
 297          * This factory function is mostly useful for when you need to connect to a
 298          * database other than the MediaWiki default (such as for external auth,
 299          * an extension, et cetera). Do not use this to connect to the MediaWiki
 300          * database. Example uses in core:
 301          * @see LoadBalancer::reallyOpenConnection()
 302          * @see ForeignDBRepo::getMasterDB()
 303          * @see WebInstallerDBConnect::execute()
 304          *
 305          * @since 1.18
 306          *
 307          * @param string $dbType A possible DB type
 308          * @param array $p An array of options to pass to the constructor.
 309          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 310          * @return IDatabase|null If the database driver or extension cannot be found
 311          * @throws InvalidArgumentException If the database driver or extension cannot be found
 312          */
 313         final public static function factory( $dbType, $p = [] ) {
 314                 $canonicalDBTypes = [
 315                         'mysql' => [ 'mysqli', 'mysql' ],
 316                         'postgres' => [],
 317                         'sqlite' => [],
 318                         'oracle' => [],
 319                         'mssql' => [],
 320                 ];
 321
 322                 $driver = false;
 323                 $dbType = strtolower( $dbType );
 324                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 325                         $possibleDrivers = $canonicalDBTypes[$dbType];
 326                         if ( !empty( $p['driver'] ) ) {
 327                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 328                                         $driver = $p['driver'];
 329                                 } else {
 330                                         throw new InvalidArgumentException( __METHOD__ .
 331                                                 " type '$dbType' does not support driver '{$p['driver']}'" );
 332                                 }
 333                         } else {
 334                                 foreach ( $possibleDrivers as $posDriver ) {
 335                                         if ( extension_loaded( $posDriver ) ) {
 336                                                 $driver = $posDriver;
 337                                                 break;
 338                                         }
 339                                 }
 340                         }
 341                 } else {
 342                         $driver = $dbType;
 343                 }
 344                 if ( $driver === false ) {
 345                         throw new InvalidArgumentException( __METHOD__ .
 346                                 " no viable database extension found for type '$dbType'" );
 347                 }
 348
 349                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 350                 // and everything else doesn't use a schema (e.g. null)
 351                 // Although postgres and oracle support schemas, we don't use them (yet)
 352                 // to maintain backwards compatibility
 353                 $defaultSchemas = [
 354                         'mssql' => 'get from global',
 355                 ];
 356
 357                 $class = 'Database' . ucfirst( $driver );
 358                 if ( class_exists( $class ) && is_subclass_of( $class, 'IDatabase' ) ) {
 359                         // Resolve some defaults for b/c
 360                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 361                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 362                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 363                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 364                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 365                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 366                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : '';
 367                         if ( !isset( $p['schema'] ) ) {
 368                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : '';
 369                         }
 370                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 371
 372                         $conn = new $class( $p );
 373                         if ( isset( $p['connLogger'] ) ) {
 374                                 $conn->connLogger = $p['connLogger'];
 375                         }
 376                         if ( isset( $p['queryLogger'] ) ) {
 377                                 $conn->queryLogger = $p['queryLogger'];
 378                         }
 379                         if ( isset( $p['errorLogger'] ) ) {
 380                                 $conn->errorLogger = $p['errorLogger'];
 381                         } else {
 382                                 $conn->errorLogger = function ( Exception $e ) {
 383                                         trigger_error( get_class( $e ) . ': ' . $e->getMessage(), E_WARNING );
 384                                 };
 385                         }
 386                 } else {
 387                         $conn = null;
 388                 }
 389
 390                 return $conn;
 391         }
 392
 393         public function setLogger( LoggerInterface $logger ) {
 394                 $this->queryLogger = $logger;
 395         }
 396
 397         public function getServerInfo() {
 398                 return $this->getServerVersion();
 399         }
 400
 401         public function bufferResults( $buffer = null ) {
 402                 $res = !$this->getFlag( DBO_NOBUFFER );
 403                 if ( $buffer !== null ) {
 404                         $buffer ? $this->clearFlag( DBO_NOBUFFER ) : $this->setFlag( DBO_NOBUFFER );
 405                 }
 406
 407                 return $res;
 408         }
 409
 410         /**
 411          * Turns on (false) or off (true) the automatic generation and sending
 412          * of a "we're sorry, but there has been a database error" page on
 413          * database errors. Default is on (false). When turned off, the
 414          * code should use lastErrno() and lastError() to handle the
 415          * situation as appropriate.
 416          *
 417          * Do not use this function outside of the Database classes.
 418          *
 419          * @param null|bool $ignoreErrors
 420          * @return bool The previous value of the flag.
 421          */
 422         protected function ignoreErrors( $ignoreErrors = null ) {
 423                 $res = $this->getFlag( DBO_IGNORE );
 424                 if ( $ignoreErrors !== null ) {
 425                         $ignoreErrors ? $this->setFlag( DBO_IGNORE ) : $this->clearFlag( DBO_IGNORE );
 426                 }
 427
 428                 return $res;
 429         }
 430
 431         public function trxLevel() {
 432                 return $this->mTrxLevel;
 433         }
 434
 435         public function trxTimestamp() {
 436                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 437         }
 438
 439         public function tablePrefix( $prefix = null ) {
 440                 $old = $this->mTablePrefix;
 441                 if ( $prefix !== null ) {
 442                         $this->mTablePrefix = $prefix;
 443                 }
 444
 445                 return $old;
 446         }
 447
 448         public function dbSchema( $schema = null ) {
 449                 $old = $this->mSchema;
 450                 if ( $schema !== null ) {
 451                         $this->mSchema = $schema;
 452                 }
 453
 454                 return $old;
 455         }
 456
 457         /**
 458          * Set the filehandle to copy write statements to.
 459          *
 460          * @param resource $fh File handle
 461          */
 462         public function setFileHandle( $fh ) {
 463                 $this->fileHandle = $fh;
 464         }
 465
 466         public function getLBInfo( $name = null ) {
 467                 if ( is_null( $name ) ) {
 468                         return $this->mLBInfo;
 469                 } else {
 470                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 471                                 return $this->mLBInfo[$name];
 472                         } else {
 473                                 return null;
 474                         }
 475                 }
 476         }
 477
 478         public function setLBInfo( $name, $value = null ) {
 479                 if ( is_null( $value ) ) {
 480                         $this->mLBInfo = $name;
 481                 } else {
 482                         $this->mLBInfo[$name] = $value;
 483                 }
 484         }
 485
 486         public function setLazyMasterHandle( IDatabase $conn ) {
 487                 $this->lazyMasterHandle = $conn;
 488         }
 489
 490         /**
 491          * @return IDatabase|null
 492          * @see setLazyMasterHandle()
 493          * @since 1.27
 494          */
 495         public function getLazyMasterHandle() {
 496                 return $this->lazyMasterHandle;
 497         }
 498
 499         public function implicitGroupby() {
 500                 return true;
 501         }
 502
 503         public function implicitOrderby() {
 504                 return true;
 505         }
 506
 507         public function lastQuery() {
 508                 return $this->mLastQuery;
 509         }
 510
 511         public function doneWrites() {
 512                 return (bool)$this->mDoneWrites;
 513         }
 514
 515         public function lastDoneWrites() {
 516                 return $this->mDoneWrites ?: false;
 517         }
 518
 519         public function writesPending() {
 520                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 521         }
 522
 523         public function writesOrCallbacksPending() {
 524                 return $this->mTrxLevel && (
 525                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 526                 );
 527         }
 528
 529         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 530                 if ( !$this->mTrxLevel ) {
 531                         return false;
 532                 } elseif ( !$this->mTrxDoneWrites ) {
 533                         return 0.0;
 534                 }
 535
 536                 switch ( $type ) {
 537                         case self::ESTIMATE_DB_APPLY:
 538                                 $this->ping( $rtt );
 539                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 540                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 541                                 // For omitted queries, make them count as something at least
 542                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 543                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 544
 545                                 return $applyTime;
 546                         default: // everything
 547                                 return $this->mTrxWriteDuration;
 548                 }
 549         }
 550
 551         public function pendingWriteCallers() {
 552                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 553         }
 554
 555         protected function pendingWriteAndCallbackCallers() {
 556                 if ( !$this->mTrxLevel ) {
 557                         return [];
 558                 }
 559
 560                 $fnames = $this->mTrxWriteCallers;
 561                 foreach ( [
 562                         $this->mTrxIdleCallbacks,
 563                         $this->mTrxPreCommitCallbacks,
 564                         $this->mTrxEndCallbacks
 565                 ] as $callbacks ) {
 566                         foreach ( $callbacks as $callback ) {
 567                                 $fnames[] = $callback[1];
 568                         }
 569                 }
 570
 571                 return $fnames;
 572         }
 573
 574         public function isOpen() {
 575                 return $this->mOpened;
 576         }
 577
 578         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 579                 if ( $remember === self::REMEMBER_PRIOR ) {
 580                         array_push( $this->priorFlags, $this->mFlags );
 581                 }
 582                 $this->mFlags |= $flag;
 583         }
 584
 585         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 586                 if ( $remember === self::REMEMBER_PRIOR ) {
 587                         array_push( $this->priorFlags, $this->mFlags );
 588                 }
 589                 $this->mFlags &= ~$flag;
 590         }
 591
 592         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 593                 if ( !$this->priorFlags ) {
 594                         return;
 595                 }
 596
 597                 if ( $state === self::RESTORE_INITIAL ) {
 598                         $this->mFlags = reset( $this->priorFlags );
 599                         $this->priorFlags = [];
 600                 } else {
 601                         $this->mFlags = array_pop( $this->priorFlags );
 602                 }
 603         }
 604
 605         public function getFlag( $flag ) {
 606                 return !!( $this->mFlags & $flag );
 607         }
 608
 609         public function getProperty( $name ) {
 610                 return $this->$name;
 611         }
 612
 613         public function getDomainID() {
 614                 if ( $this->mTablePrefix != '' ) {
 615                         return "{$this->mDBname}-{$this->mTablePrefix}";
 616                 } else {
 617                         return $this->mDBname;
 618                 }
 619         }
 620
 621         final public function getWikiID() {
 622                 return $this->getDomainID();
 623         }
 624
 625         /**
 626          * Get information about an index into an object
 627          * @param string $table Table name
 628          * @param string $index Index name
 629          * @param string $fname Calling function name
 630          * @return mixed Database-specific index description class or false if the index does not exist
 631          */
 632         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 633
 634         /**
 635          * Wrapper for addslashes()
 636          *
 637          * @param string $s String to be slashed.
 638          * @return string Slashed string.
 639          */
 640         abstract function strencode( $s );
 641
 642         protected function installErrorHandler() {
 643                 $this->mPHPError = false;
 644                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 645                 set_error_handler( [ $this, 'connectionerrorLogger' ] );
 646         }
 647
 648         /**
 649          * @return bool|string
 650          */
 651         protected function restoreErrorHandler() {
 652                 restore_error_handler();
 653                 if ( $this->htmlErrors !== false ) {
 654                         ini_set( 'html_errors', $this->htmlErrors );
 655                 }
 656                 if ( $this->mPHPError ) {
 657                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 658                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 659
 660                         return $error;
 661                 } else {
 662                         return false;
 663                 }
 664         }
 665
 666         /**
 667          * @param int $errno
 668          * @param string $errstr
 669          */
 670         public function connectionerrorLogger( $errno, $errstr ) {
 671                 $this->mPHPError = $errstr;
 672         }
 673
 674         /**
 675          * Create a log context to pass to PSR logging functions.
 676          *
 677          * @param array $extras Additional data to add to context
 678          * @return array
 679          */
 680         protected function getLogContext( array $extras = [] ) {
 681                 return array_merge(
 682                         [
 683                                 'db_server' => $this->mServer,
 684                                 'db_name' => $this->mDBname,
 685                                 'db_user' => $this->mUser,
 686                         ],
 687                         $extras
 688                 );
 689         }
 690
 691         public function close() {
 692                 if ( $this->mConn ) {
 693                         if ( $this->trxLevel() ) {
 694                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 695                         }
 696
 697                         $closed = $this->closeConnection();
 698                         $this->mConn = false;
 699                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 700                         throw new RuntimeException( "Transaction callbacks still pending." );
 701                 } else {
 702                         $closed = true;
 703                 }
 704                 $this->mOpened = false;
 705
 706                 return $closed;
 707         }
 708
 709         /**
 710          * Make sure isOpen() returns true as a sanity check
 711          *
 712          * @throws DBUnexpectedError
 713          */
 714         protected function assertOpen() {
 715                 if ( !$this->isOpen() ) {
 716                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 717                 }
 718         }
 719
 720         /**
 721          * Closes underlying database connection
 722          * @since 1.20
 723          * @return bool Whether connection was closed successfully
 724          */
 725         abstract protected function closeConnection();
 726
 727         function reportConnectionError( $error = 'Unknown error' ) {
 728                 $myError = $this->lastError();
 729                 if ( $myError ) {
 730                         $error = $myError;
 731                 }
 732
 733                 # New method
 734                 throw new DBConnectionError( $this, $error );
 735         }
 736
 737         /**
 738          * The DBMS-dependent part of query()
 739          *
 740          * @param string $sql SQL query.
 741          * @return ResultWrapper|bool Result object to feed to fetchObject,
 742          *   fetchRow, ...; or false on failure
 743          */
 744         abstract protected function doQuery( $sql );
 745
 746         /**
 747          * Determine whether a query writes to the DB.
 748          * Should return true if unsure.
 749          *
 750          * @param string $sql
 751          * @return bool
 752          */
 753         protected function isWriteQuery( $sql ) {
 754                 return !preg_match(
 755                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 756         }
 757
 758         /**
 759          * @param $sql
 760          * @return string|null
 761          */
 762         protected function getQueryVerb( $sql ) {
 763                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 764         }
 765
 766         /**
 767          * Determine whether a SQL statement is sensitive to isolation level.
 768          * A SQL statement is considered transactable if its result could vary
 769          * depending on the transaction isolation level. Operational commands
 770          * such as 'SET' and 'SHOW' are not considered to be transactable.
 771          *
 772          * @param string $sql
 773          * @return bool
 774          */
 775         protected function isTransactableQuery( $sql ) {
 776                 $verb = $this->getQueryVerb( $sql );
 777                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 778         }
 779
 780         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 781                 $priorWritesPending = $this->writesOrCallbacksPending();
 782                 $this->mLastQuery = $sql;
 783
 784                 $isWrite = $this->isWriteQuery( $sql );
 785                 if ( $isWrite ) {
 786                         $reason = $this->getReadOnlyReason();
 787                         if ( $reason !== false ) {
 788                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 789                         }
 790                         # Set a flag indicating that writes have been done
 791                         $this->mDoneWrites = microtime( true );
 792                 }
 793
 794                 // Add trace comment to the begin of the sql string, right after the operator.
 795                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 796                 $commentedSql = preg_replace( '/\s|$/', " /* $fname {$this->agent} */ ", $sql, 1 );
 797
 798                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 799                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 800                         && $this->isTransactableQuery( $sql )
 801                 ) {
 802                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 803                         $this->mTrxAutomatic = true;
 804                 }
 805
 806                 # Keep track of whether the transaction has write queries pending
 807                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 808                         $this->mTrxDoneWrites = true;
 809                         $this->trxProfiler->transactionWritingIn(
 810                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 811                 }
 812
 813                 if ( $this->getFlag( DBO_DEBUG ) ) {
 814                         $this->queryLogger->debug( "{$this->mDBname} {$commentedSql}" );
 815                 }
 816
 817                 # Avoid fatals if close() was called
 818                 $this->assertOpen();
 819
 820                 # Send the query to the server
 821                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 822
 823                 # Try reconnecting if the connection was lost
 824                 if ( false === $ret && $this->wasErrorReissuable() ) {
 825                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 826                         # Stash the last error values before anything might clear them
 827                         $lastError = $this->lastError();
 828                         $lastErrno = $this->lastErrno();
 829                         # Update state tracking to reflect transaction loss due to disconnection
 830                         $this->handleTransactionLoss();
 831                         if ( $this->reconnect() ) {
 832                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 833                                 $this->connLogger->warning( $msg );
 834                                 $this->queryLogger->warning(
 835                                         "$msg:\n" . ( new RuntimeException() )->getTraceAsString() );
 836
 837                                 if ( !$recoverable ) {
 838                                         # Callers may catch the exception and continue to use the DB
 839                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 840                                 } else {
 841                                         # Should be safe to silently retry the query
 842                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 843                                 }
 844                         } else {
 845                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()} permanently";
 846                                 $this->connLogger->error( $msg );
 847                         }
 848                 }
 849
 850                 if ( false === $ret ) {
 851                         # Deadlocks cause the entire transaction to abort, not just the statement.
 852                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 853                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 854                         if ( $this->wasDeadlock() ) {
 855                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 856                                         $tempIgnore = false; // not recoverable
 857                                 }
 858                                 # Update state tracking to reflect transaction loss
 859                                 $this->handleTransactionLoss();
 860                         }
 861
 862                         $this->reportQueryError(
 863                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 864                 }
 865
 866                 $res = $this->resultObject( $ret );
 867
 868                 return $res;
 869         }
 870
 871         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 872                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 873                 # generalizeSQL() will probably cut down the query to reasonable
 874                 # logging size most of the time. The substr is really just a sanity check.
 875                 if ( $isMaster ) {
 876                         $queryProf = 'query-m: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 877                 } else {
 878                         $queryProf = 'query: ' . substr( self::generalizeSQL( $sql ), 0, 255 );
 879                 }
 880
 881                 # Include query transaction state
 882                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 883
 884                 $startTime = microtime( true );
 885                 if ( $this->profiler ) {
 886                         call_user_func( [ $this->profiler, 'profileIn' ], $queryProf );
 887                 }
 888                 $ret = $this->doQuery( $commentedSql );
 889                 if ( $this->profiler ) {
 890                         call_user_func( [ $this->profiler, 'profileOut' ], $queryProf );
 891                 }
 892                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 893
 894                 unset( $queryProfSection ); // profile out (if set)
 895
 896                 if ( $ret !== false ) {
 897                         $this->lastPing = $startTime;
 898                         if ( $isWrite && $this->mTrxLevel ) {
 899                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 900                                 $this->mTrxWriteCallers[] = $fname;
 901                         }
 902                 }
 903
 904                 if ( $sql === self::PING_QUERY ) {
 905                         $this->mRTTEstimate = $queryRuntime;
 906                 }
 907
 908                 $this->trxProfiler->recordQueryCompletion(
 909                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 910                 );
 911                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
 912
 913                 return $ret;
 914         }
 915
 916         /**
 917          * Update the estimated run-time of a query, not counting large row lock times
 918          *
 919          * LoadBalancer can be set to rollback transactions that will create huge replication
 920          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
 921          * queries, like inserting a row can take a long time due to row locking. This method
 922          * uses some simple heuristics to discount those cases.
 923          *
 924          * @param string $sql A SQL write query
 925          * @param float $runtime Total runtime, including RTT
 926          */
 927         private function updateTrxWriteQueryTime( $sql, $runtime ) {
 928                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
 929                 $indicativeOfReplicaRuntime = true;
 930                 if ( $runtime > self::SLOW_WRITE_SEC ) {
 931                         $verb = $this->getQueryVerb( $sql );
 932                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
 933                         if ( $verb === 'INSERT' ) {
 934                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
 935                         } elseif ( $verb === 'REPLACE' ) {
 936                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
 937                         }
 938                 }
 939
 940                 $this->mTrxWriteDuration += $runtime;
 941                 $this->mTrxWriteQueryCount += 1;
 942                 if ( $indicativeOfReplicaRuntime ) {
 943                         $this->mTrxWriteAdjDuration += $runtime;
 944                         $this->mTrxWriteAdjQueryCount += 1;
 945                 }
 946         }
 947
 948         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
 949                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
 950                 # Dropped connections also mean that named locks are automatically released.
 951                 # Only allow error suppression in autocommit mode or when the lost transaction
 952                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
 953                 if ( $this->mNamedLocksHeld ) {
 954                         return false; // possible critical section violation
 955                 } elseif ( $sql === 'COMMIT' ) {
 956                         return !$priorWritesPending; // nothing written anyway? (T127428)
 957                 } elseif ( $sql === 'ROLLBACK' ) {
 958                         return true; // transaction lost...which is also what was requested :)
 959                 } elseif ( $this->explicitTrxActive() ) {
 960                         return false; // don't drop atomocity
 961                 } elseif ( $priorWritesPending ) {
 962                         return false; // prior writes lost from implicit transaction
 963                 }
 964
 965                 return true;
 966         }
 967
 968         private function handleTransactionLoss() {
 969                 $this->mTrxLevel = 0;
 970                 $this->mTrxIdleCallbacks = []; // bug 65263
 971                 $this->mTrxPreCommitCallbacks = []; // bug 65263
 972                 try {
 973                         // Handle callbacks in mTrxEndCallbacks
 974                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
 975                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
 976                         return null;
 977                 } catch ( Exception $e ) {
 978                         // Already logged; move on...
 979                         return $e;
 980                 }
 981         }
 982
 983         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 984                 if ( $this->ignoreErrors() || $tempIgnore ) {
 985                         $this->queryLogger->debug( "SQL ERROR (ignored): $error\n" );
 986                 } else {
 987                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
 988                         $this->queryLogger->error(
 989                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
 990                                 $this->getLogContext( [
 991                                         'method' => __METHOD__,
 992                                         'errno' => $errno,
 993                                         'error' => $error,
 994                                         'sql1line' => $sql1line,
 995                                         'fname' => $fname,
 996                                 ] )
 997                         );
 998                         $this->queryLogger->debug( "SQL ERROR: " . $error . "\n" );
 999                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1000                 }
1001         }
1002
1003         public function freeResult( $res ) {
1004         }
1005
1006         public function selectField(
1007                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1008         ) {
1009                 if ( $var === '*' ) { // sanity
1010                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1011                 }
1012
1013                 if ( !is_array( $options ) ) {
1014                         $options = [ $options ];
1015                 }
1016
1017                 $options['LIMIT'] = 1;
1018
1019                 $res = $this->select( $table, $var, $cond, $fname, $options );
1020                 if ( $res === false || !$this->numRows( $res ) ) {
1021                         return false;
1022                 }
1023
1024                 $row = $this->fetchRow( $res );
1025
1026                 if ( $row !== false ) {
1027                         return reset( $row );
1028                 } else {
1029                         return false;
1030                 }
1031         }
1032
1033         public function selectFieldValues(
1034                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1035         ) {
1036                 if ( $var === '*' ) { // sanity
1037                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1038                 } elseif ( !is_string( $var ) ) { // sanity
1039                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1040                 }
1041
1042                 if ( !is_array( $options ) ) {
1043                         $options = [ $options ];
1044                 }
1045
1046                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1047                 if ( $res === false ) {
1048                         return false;
1049                 }
1050
1051                 $values = [];
1052                 foreach ( $res as $row ) {
1053                         $values[] = $row->$var;
1054                 }
1055
1056                 return $values;
1057         }
1058
1059         /**
1060          * Returns an optional USE INDEX clause to go after the table, and a
1061          * string to go at the end of the query.
1062          *
1063          * @param array $options Associative array of options to be turned into
1064          *   an SQL query, valid keys are listed in the function.
1065          * @return array
1066          * @see DatabaseBase::select()
1067          */
1068         public function makeSelectOptions( $options ) {
1069                 $preLimitTail = $postLimitTail = '';
1070                 $startOpts = '';
1071
1072                 $noKeyOptions = [];
1073
1074                 foreach ( $options as $key => $option ) {
1075                         if ( is_numeric( $key ) ) {
1076                                 $noKeyOptions[$option] = true;
1077                         }
1078                 }
1079
1080                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1081
1082                 $preLimitTail .= $this->makeOrderBy( $options );
1083
1084                 // if (isset($options['LIMIT'])) {
1085                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1086                 //              isset($options['OFFSET']) ? $options['OFFSET']
1087                 //              : false);
1088                 // }
1089
1090                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1091                         $postLimitTail .= ' FOR UPDATE';
1092                 }
1093
1094                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1095                         $postLimitTail .= ' LOCK IN SHARE MODE';
1096                 }
1097
1098                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1099                         $startOpts .= 'DISTINCT';
1100                 }
1101
1102                 # Various MySQL extensions
1103                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1104                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1105                 }
1106
1107                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1108                         $startOpts .= ' HIGH_PRIORITY';
1109                 }
1110
1111                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1112                         $startOpts .= ' SQL_BIG_RESULT';
1113                 }
1114
1115                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1116                         $startOpts .= ' SQL_BUFFER_RESULT';
1117                 }
1118
1119                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1120                         $startOpts .= ' SQL_SMALL_RESULT';
1121                 }
1122
1123                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1124                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1125                 }
1126
1127                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1128                         $startOpts .= ' SQL_CACHE';
1129                 }
1130
1131                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1132                         $startOpts .= ' SQL_NO_CACHE';
1133                 }
1134
1135                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1136                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1137                 } else {
1138                         $useIndex = '';
1139                 }
1140                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1141                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1142                 } else {
1143                         $ignoreIndex = '';
1144                 }
1145
1146                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1147         }
1148
1149         /**
1150          * Returns an optional GROUP BY with an optional HAVING
1151          *
1152          * @param array $options Associative array of options
1153          * @return string
1154          * @see DatabaseBase::select()
1155          * @since 1.21
1156          */
1157         public function makeGroupByWithHaving( $options ) {
1158                 $sql = '';
1159                 if ( isset( $options['GROUP BY'] ) ) {
1160                         $gb = is_array( $options['GROUP BY'] )
1161                                 ? implode( ',', $options['GROUP BY'] )
1162                                 : $options['GROUP BY'];
1163                         $sql .= ' GROUP BY ' . $gb;
1164                 }
1165                 if ( isset( $options['HAVING'] ) ) {
1166                         $having = is_array( $options['HAVING'] )
1167                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1168                                 : $options['HAVING'];
1169                         $sql .= ' HAVING ' . $having;
1170                 }
1171
1172                 return $sql;
1173         }
1174
1175         /**
1176          * Returns an optional ORDER BY
1177          *
1178          * @param array $options Associative array of options
1179          * @return string
1180          * @see DatabaseBase::select()
1181          * @since 1.21
1182          */
1183         public function makeOrderBy( $options ) {
1184                 if ( isset( $options['ORDER BY'] ) ) {
1185                         $ob = is_array( $options['ORDER BY'] )
1186                                 ? implode( ',', $options['ORDER BY'] )
1187                                 : $options['ORDER BY'];
1188
1189                         return ' ORDER BY ' . $ob;
1190                 }
1191
1192                 return '';
1193         }
1194
1195         // See IDatabase::select for the docs for this function
1196         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1197                 $options = [], $join_conds = [] ) {
1198                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1199
1200                 return $this->query( $sql, $fname );
1201         }
1202
1203         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1204                 $options = [], $join_conds = []
1205         ) {
1206                 if ( is_array( $vars ) ) {
1207                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1208                 }
1209
1210                 $options = (array)$options;
1211                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1212                         ? $options['USE INDEX']
1213                         : [];
1214                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1215                         ? $options['IGNORE INDEX']
1216                         : [];
1217
1218                 if ( is_array( $table ) ) {
1219                         $from = ' FROM ' .
1220                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1221                 } elseif ( $table != '' ) {
1222                         if ( $table[0] == ' ' ) {
1223                                 $from = ' FROM ' . $table;
1224                         } else {
1225                                 $from = ' FROM ' .
1226                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1227                         }
1228                 } else {
1229                         $from = '';
1230                 }
1231
1232                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1233                         $this->makeSelectOptions( $options );
1234
1235                 if ( !empty( $conds ) ) {
1236                         if ( is_array( $conds ) ) {
1237                                 $conds = $this->makeList( $conds, LIST_AND );
1238                         }
1239                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1240                 } else {
1241                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1242                 }
1243
1244                 if ( isset( $options['LIMIT'] ) ) {
1245                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1246                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1247                 }
1248                 $sql = "$sql $postLimitTail";
1249
1250                 if ( isset( $options['EXPLAIN'] ) ) {
1251                         $sql = 'EXPLAIN ' . $sql;
1252                 }
1253
1254                 return $sql;
1255         }
1256
1257         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1258                 $options = [], $join_conds = []
1259         ) {
1260                 $options = (array)$options;
1261                 $options['LIMIT'] = 1;
1262                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1263
1264                 if ( $res === false ) {
1265                         return false;
1266                 }
1267
1268                 if ( !$this->numRows( $res ) ) {
1269                         return false;
1270                 }
1271
1272                 $obj = $this->fetchObject( $res );
1273
1274                 return $obj;
1275         }
1276
1277         public function estimateRowCount(
1278                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1279         ) {
1280                 $rows = 0;
1281                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1282
1283                 if ( $res ) {
1284                         $row = $this->fetchRow( $res );
1285                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1286                 }
1287
1288                 return $rows;
1289         }
1290
1291         public function selectRowCount(
1292                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1293         ) {
1294                 $rows = 0;
1295                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1296                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1297
1298                 if ( $res ) {
1299                         $row = $this->fetchRow( $res );
1300                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1301                 }
1302
1303                 return $rows;
1304         }
1305
1306         /**
1307          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1308          * It's only slightly flawed. Don't use for anything important.
1309          *
1310          * @param string $sql A SQL Query
1311          *
1312          * @return string
1313          */
1314         protected static function generalizeSQL( $sql ) {
1315                 # This does the same as the regexp below would do, but in such a way
1316                 # as to avoid crashing php on some large strings.
1317                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1318
1319                 $sql = str_replace( "\\\\", '', $sql );
1320                 $sql = str_replace( "\\'", '', $sql );
1321                 $sql = str_replace( "\\\"", '', $sql );
1322                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1323                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1324
1325                 # All newlines, tabs, etc replaced by single space
1326                 $sql = preg_replace( '/\s+/', ' ', $sql );
1327
1328                 # All numbers => N,
1329                 # except the ones surrounded by characters, e.g. l10n
1330                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1331                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1332
1333                 return $sql;
1334         }
1335
1336         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1337                 $info = $this->fieldInfo( $table, $field );
1338
1339                 return (bool)$info;
1340         }
1341
1342         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1343                 if ( !$this->tableExists( $table ) ) {
1344                         return null;
1345                 }
1346
1347                 $info = $this->indexInfo( $table, $index, $fname );
1348                 if ( is_null( $info ) ) {
1349                         return null;
1350                 } else {
1351                         return $info !== false;
1352                 }
1353         }
1354
1355         public function tableExists( $table, $fname = __METHOD__ ) {
1356                 $table = $this->tableName( $table );
1357                 $old = $this->ignoreErrors( true );
1358                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1359                 $this->ignoreErrors( $old );
1360
1361                 return (bool)$res;
1362         }
1363
1364         public function indexUnique( $table, $index ) {
1365                 $indexInfo = $this->indexInfo( $table, $index );
1366
1367                 if ( !$indexInfo ) {
1368                         return null;
1369                 }
1370
1371                 return !$indexInfo[0]->Non_unique;
1372         }
1373
1374         /**
1375          * Helper for DatabaseBase::insert().
1376          *
1377          * @param array $options
1378          * @return string
1379          */
1380         protected function makeInsertOptions( $options ) {
1381                 return implode( ' ', $options );
1382         }
1383
1384         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1385                 # No rows to insert, easy just return now
1386                 if ( !count( $a ) ) {
1387                         return true;
1388                 }
1389
1390                 $table = $this->tableName( $table );
1391
1392                 if ( !is_array( $options ) ) {
1393                         $options = [ $options ];
1394                 }
1395
1396                 $fh = null;
1397                 if ( isset( $options['fileHandle'] ) ) {
1398                         $fh = $options['fileHandle'];
1399                 }
1400                 $options = $this->makeInsertOptions( $options );
1401
1402                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1403                         $multi = true;
1404                         $keys = array_keys( $a[0] );
1405                 } else {
1406                         $multi = false;
1407                         $keys = array_keys( $a );
1408                 }
1409
1410                 $sql = 'INSERT ' . $options .
1411                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1412
1413                 if ( $multi ) {
1414                         $first = true;
1415                         foreach ( $a as $row ) {
1416                                 if ( $first ) {
1417                                         $first = false;
1418                                 } else {
1419                                         $sql .= ',';
1420                                 }
1421                                 $sql .= '(' . $this->makeList( $row ) . ')';
1422                         }
1423                 } else {
1424                         $sql .= '(' . $this->makeList( $a ) . ')';
1425                 }
1426
1427                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1428                         return false;
1429                 } elseif ( $fh !== null ) {
1430                         return true;
1431                 }
1432
1433                 return (bool)$this->query( $sql, $fname );
1434         }
1435
1436         /**
1437          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1438          *
1439          * @param array $options
1440          * @return array
1441          */
1442         protected function makeUpdateOptionsArray( $options ) {
1443                 if ( !is_array( $options ) ) {
1444                         $options = [ $options ];
1445                 }
1446
1447                 $opts = [];
1448
1449                 if ( in_array( 'IGNORE', $options ) ) {
1450                         $opts[] = 'IGNORE';
1451                 }
1452
1453                 return $opts;
1454         }
1455
1456         /**
1457          * Make UPDATE options for the DatabaseBase::update function
1458          *
1459          * @param array $options The options passed to DatabaseBase::update
1460          * @return string
1461          */
1462         protected function makeUpdateOptions( $options ) {
1463                 $opts = $this->makeUpdateOptionsArray( $options );
1464
1465                 return implode( ' ', $opts );
1466         }
1467
1468         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1469                 $table = $this->tableName( $table );
1470                 $opts = $this->makeUpdateOptions( $options );
1471                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1472
1473                 if ( $conds !== [] && $conds !== '*' ) {
1474                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1475                 }
1476
1477                 return $this->query( $sql, $fname );
1478         }
1479
1480         public function makeList( $a, $mode = LIST_COMMA ) {
1481                 if ( !is_array( $a ) ) {
1482                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
1483                 }
1484
1485                 $first = true;
1486                 $list = '';
1487
1488                 foreach ( $a as $field => $value ) {
1489                         if ( !$first ) {
1490                                 if ( $mode == LIST_AND ) {
1491                                         $list .= ' AND ';
1492                                 } elseif ( $mode == LIST_OR ) {
1493                                         $list .= ' OR ';
1494                                 } else {
1495                                         $list .= ',';
1496                                 }
1497                         } else {
1498                                 $first = false;
1499                         }
1500
1501                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1502                                 $list .= "($value)";
1503                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1504                                 $list .= "$value";
1505                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1506                                 // Remove null from array to be handled separately if found
1507                                 $includeNull = false;
1508                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1509                                         $includeNull = true;
1510                                         unset( $value[$nullKey] );
1511                                 }
1512                                 if ( count( $value ) == 0 && !$includeNull ) {
1513                                         throw new InvalidArgumentException( __METHOD__ . ": empty input for field $field" );
1514                                 } elseif ( count( $value ) == 0 ) {
1515                                         // only check if $field is null
1516                                         $list .= "$field IS NULL";
1517                                 } else {
1518                                         // IN clause contains at least one valid element
1519                                         if ( $includeNull ) {
1520                                                 // Group subconditions to ensure correct precedence
1521                                                 $list .= '(';
1522                                         }
1523                                         if ( count( $value ) == 1 ) {
1524                                                 // Special-case single values, as IN isn't terribly efficient
1525                                                 // Don't necessarily assume the single key is 0; we don't
1526                                                 // enforce linear numeric ordering on other arrays here.
1527                                                 $value = array_values( $value )[0];
1528                                                 $list .= $field . " = " . $this->addQuotes( $value );
1529                                         } else {
1530                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1531                                         }
1532                                         // if null present in array, append IS NULL
1533                                         if ( $includeNull ) {
1534                                                 $list .= " OR $field IS NULL)";
1535                                         }
1536                                 }
1537                         } elseif ( $value === null ) {
1538                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1539                                         $list .= "$field IS ";
1540                                 } elseif ( $mode == LIST_SET ) {
1541                                         $list .= "$field = ";
1542                                 }
1543                                 $list .= 'NULL';
1544                         } else {
1545                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1546                                         $list .= "$field = ";
1547                                 }
1548                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1549                         }
1550                 }
1551
1552                 return $list;
1553         }
1554
1555         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1556                 $conds = [];
1557
1558                 foreach ( $data as $base => $sub ) {
1559                         if ( count( $sub ) ) {
1560                                 $conds[] = $this->makeList(
1561                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1562                                         LIST_AND );
1563                         }
1564                 }
1565
1566                 if ( $conds ) {
1567                         return $this->makeList( $conds, LIST_OR );
1568                 } else {
1569                         // Nothing to search for...
1570                         return false;
1571                 }
1572         }
1573
1574         /**
1575          * Return aggregated value alias
1576          *
1577          * @param array $valuedata
1578          * @param string $valuename
1579          *
1580          * @return string
1581          */
1582         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1583                 return $valuename;
1584         }
1585
1586         public function bitNot( $field ) {
1587                 return "(~$field)";
1588         }
1589
1590         public function bitAnd( $fieldLeft, $fieldRight ) {
1591                 return "($fieldLeft & $fieldRight)";
1592         }
1593
1594         public function bitOr( $fieldLeft, $fieldRight ) {
1595                 return "($fieldLeft | $fieldRight)";
1596         }
1597
1598         public function buildConcat( $stringList ) {
1599                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1600         }
1601
1602         public function buildGroupConcatField(
1603                 $delim, $table, $field, $conds = '', $join_conds = []
1604         ) {
1605                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1606
1607                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1608         }
1609
1610         /**
1611          * @param string $field Field or column to cast
1612          * @return string
1613          * @since 1.28
1614          */
1615         public function buildStringCast( $field ) {
1616                 return $field;
1617         }
1618
1619         public function selectDB( $db ) {
1620                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1621                 # if your database engine supports a concept similar to MySQL's
1622                 # databases you may as well.
1623                 $this->mDBname = $db;
1624
1625                 return true;
1626         }
1627
1628         public function getDBname() {
1629                 return $this->mDBname;
1630         }
1631
1632         public function getServer() {
1633                 return $this->mServer;
1634         }
1635
1636         /**
1637          * Format a table name ready for use in constructing an SQL query
1638          *
1639          * This does two important things: it quotes the table names to clean them up,
1640          * and it adds a table prefix if only given a table name with no quotes.
1641          *
1642          * All functions of this object which require a table name call this function
1643          * themselves. Pass the canonical name to such functions. This is only needed
1644          * when calling query() directly.
1645          *
1646          * @note This function does not sanitize user input. It is not safe to use
1647          *   this function to escape user input.
1648          * @param string $name Database table name
1649          * @param string $format One of:
1650          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1651          *            so that it can be used in a query.
1652          *   raw - Do not add identifier quotes to the table name
1653          * @return string Full database name
1654          */
1655         public function tableName( $name, $format = 'quoted' ) {
1656                 # Skip the entire process when we have a string quoted on both ends.
1657                 # Note that we check the end so that we will still quote any use of
1658                 # use of `database`.table. But won't break things if someone wants
1659                 # to query a database table with a dot in the name.
1660                 if ( $this->isQuotedIdentifier( $name ) ) {
1661                         return $name;
1662                 }
1663
1664                 # Lets test for any bits of text that should never show up in a table
1665                 # name. Basically anything like JOIN or ON which are actually part of
1666                 # SQL queries, but may end up inside of the table value to combine
1667                 # sql. Such as how the API is doing.
1668                 # Note that we use a whitespace test rather than a \b test to avoid
1669                 # any remote case where a word like on may be inside of a table name
1670                 # surrounded by symbols which may be considered word breaks.
1671                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1672                         return $name;
1673                 }
1674
1675                 # Split database and table into proper variables.
1676                 # We reverse the explode so that database.table and table both output
1677                 # the correct table.
1678                 $dbDetails = explode( '.', $name, 3 );
1679                 if ( count( $dbDetails ) == 3 ) {
1680                         list( $database, $schema, $table ) = $dbDetails;
1681                         # We don't want any prefix added in this case
1682                         $prefix = '';
1683                 } elseif ( count( $dbDetails ) == 2 ) {
1684                         list( $database, $table ) = $dbDetails;
1685                         # We don't want any prefix added in this case
1686                         # In dbs that support it, $database may actually be the schema
1687                         # but that doesn't affect any of the functionality here
1688                         $prefix = '';
1689                         $schema = '';
1690                 } else {
1691                         list( $table ) = $dbDetails;
1692                         if ( isset( $this->tableAliases[$table] ) ) {
1693                                 $database = $this->tableAliases[$table]['dbname'];
1694                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1695                                         ? $this->tableAliases[$table]['schema']
1696                                         : $this->mSchema;
1697                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1698                                         ? $this->tableAliases[$table]['prefix']
1699                                         : $this->mTablePrefix;
1700                         } else {
1701                                 $database = '';
1702                                 $schema = $this->mSchema; # Default schema
1703                                 $prefix = $this->mTablePrefix; # Default prefix
1704                         }
1705                 }
1706
1707                 # Quote $table and apply the prefix if not quoted.
1708                 # $tableName might be empty if this is called from Database::replaceVars()
1709                 $tableName = "{$prefix}{$table}";
1710                 if ( $format == 'quoted'
1711                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1712                 ) {
1713                         $tableName = $this->addIdentifierQuotes( $tableName );
1714                 }
1715
1716                 # Quote $schema and merge it with the table name if needed
1717                 if ( strlen( $schema ) ) {
1718                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1719                                 $schema = $this->addIdentifierQuotes( $schema );
1720                         }
1721                         $tableName = $schema . '.' . $tableName;
1722                 }
1723
1724                 # Quote $database and merge it with the table name if needed
1725                 if ( $database !== '' ) {
1726                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1727                                 $database = $this->addIdentifierQuotes( $database );
1728                         }
1729                         $tableName = $database . '.' . $tableName;
1730                 }
1731
1732                 return $tableName;
1733         }
1734
1735         /**
1736          * Fetch a number of table names into an array
1737          * This is handy when you need to construct SQL for joins
1738          *
1739          * Example:
1740          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1741          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1742          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1743          *
1744          * @return array
1745          */
1746         public function tableNames() {
1747                 $inArray = func_get_args();
1748                 $retVal = [];
1749
1750                 foreach ( $inArray as $name ) {
1751                         $retVal[$name] = $this->tableName( $name );
1752                 }
1753
1754                 return $retVal;
1755         }
1756
1757         /**
1758          * Fetch a number of table names into an zero-indexed numerical array
1759          * This is handy when you need to construct SQL for joins
1760          *
1761          * Example:
1762          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1763          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1764          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1765          *
1766          * @return array
1767          */
1768         public function tableNamesN() {
1769                 $inArray = func_get_args();
1770                 $retVal = [];
1771
1772                 foreach ( $inArray as $name ) {
1773                         $retVal[] = $this->tableName( $name );
1774                 }
1775
1776                 return $retVal;
1777         }
1778
1779         /**
1780          * Get an aliased table name
1781          * e.g. tableName AS newTableName
1782          *
1783          * @param string $name Table name, see tableName()
1784          * @param string|bool $alias Alias (optional)
1785          * @return string SQL name for aliased table. Will not alias a table to its own name
1786          */
1787         public function tableNameWithAlias( $name, $alias = false ) {
1788                 if ( !$alias || $alias == $name ) {
1789                         return $this->tableName( $name );
1790                 } else {
1791                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1792                 }
1793         }
1794
1795         /**
1796          * Gets an array of aliased table names
1797          *
1798          * @param array $tables [ [alias] => table ]
1799          * @return string[] See tableNameWithAlias()
1800          */
1801         public function tableNamesWithAlias( $tables ) {
1802                 $retval = [];
1803                 foreach ( $tables as $alias => $table ) {
1804                         if ( is_numeric( $alias ) ) {
1805                                 $alias = $table;
1806                         }
1807                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1808                 }
1809
1810                 return $retval;
1811         }
1812
1813         /**
1814          * Get an aliased field name
1815          * e.g. fieldName AS newFieldName
1816          *
1817          * @param string $name Field name
1818          * @param string|bool $alias Alias (optional)
1819          * @return string SQL name for aliased field. Will not alias a field to its own name
1820          */
1821         public function fieldNameWithAlias( $name, $alias = false ) {
1822                 if ( !$alias || (string)$alias === (string)$name ) {
1823                         return $name;
1824                 } else {
1825                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1826                 }
1827         }
1828
1829         /**
1830          * Gets an array of aliased field names
1831          *
1832          * @param array $fields [ [alias] => field ]
1833          * @return string[] See fieldNameWithAlias()
1834          */
1835         public function fieldNamesWithAlias( $fields ) {
1836                 $retval = [];
1837                 foreach ( $fields as $alias => $field ) {
1838                         if ( is_numeric( $alias ) ) {
1839                                 $alias = $field;
1840                         }
1841                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1842                 }
1843
1844                 return $retval;
1845         }
1846
1847         /**
1848          * Get the aliased table name clause for a FROM clause
1849          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1850          *
1851          * @param array $tables ( [alias] => table )
1852          * @param array $use_index Same as for select()
1853          * @param array $ignore_index Same as for select()
1854          * @param array $join_conds Same as for select()
1855          * @return string
1856          */
1857         protected function tableNamesWithIndexClauseOrJOIN(
1858                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1859         ) {
1860                 $ret = [];
1861                 $retJOIN = [];
1862                 $use_index = (array)$use_index;
1863                 $ignore_index = (array)$ignore_index;
1864                 $join_conds = (array)$join_conds;
1865
1866                 foreach ( $tables as $alias => $table ) {
1867                         if ( !is_string( $alias ) ) {
1868                                 // No alias? Set it equal to the table name
1869                                 $alias = $table;
1870                         }
1871                         // Is there a JOIN clause for this table?
1872                         if ( isset( $join_conds[$alias] ) ) {
1873                                 list( $joinType, $conds ) = $join_conds[$alias];
1874                                 $tableClause = $joinType;
1875                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1876                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1877                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1878                                         if ( $use != '' ) {
1879                                                 $tableClause .= ' ' . $use;
1880                                         }
1881                                 }
1882                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1883                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1884                                         if ( $ignore != '' ) {
1885                                                 $tableClause .= ' ' . $ignore;
1886                                         }
1887                                 }
1888                                 $on = $this->makeList( (array)$conds, LIST_AND );
1889                                 if ( $on != '' ) {
1890                                         $tableClause .= ' ON (' . $on . ')';
1891                                 }
1892
1893                                 $retJOIN[] = $tableClause;
1894                         } elseif ( isset( $use_index[$alias] ) ) {
1895                                 // Is there an INDEX clause for this table?
1896                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1897                                 $tableClause .= ' ' . $this->useIndexClause(
1898                                                 implode( ',', (array)$use_index[$alias] )
1899                                         );
1900
1901                                 $ret[] = $tableClause;
1902                         } elseif ( isset( $ignore_index[$alias] ) ) {
1903                                 // Is there an INDEX clause for this table?
1904                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1905                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1906                                                 implode( ',', (array)$ignore_index[$alias] )
1907                                         );
1908
1909                                 $ret[] = $tableClause;
1910                         } else {
1911                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1912
1913                                 $ret[] = $tableClause;
1914                         }
1915                 }
1916
1917                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1918                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1919                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1920
1921                 // Compile our final table clause
1922                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1923         }
1924
1925         /**
1926          * Get the name of an index in a given table.
1927          *
1928          * @param string $index
1929          * @return string
1930          */
1931         protected function indexName( $index ) {
1932                 // Backwards-compatibility hack
1933                 $renamed = [
1934                         'ar_usertext_timestamp' => 'usertext_timestamp',
1935                         'un_user_id' => 'user_id',
1936                         'un_user_ip' => 'user_ip',
1937                 ];
1938
1939                 if ( isset( $renamed[$index] ) ) {
1940                         return $renamed[$index];
1941                 } else {
1942                         return $index;
1943                 }
1944         }
1945
1946         public function addQuotes( $s ) {
1947                 if ( $s instanceof Blob ) {
1948                         $s = $s->fetch();
1949                 }
1950                 if ( $s === null ) {
1951                         return 'NULL';
1952                 } else {
1953                         # This will also quote numeric values. This should be harmless,
1954                         # and protects against weird problems that occur when they really
1955                         # _are_ strings such as article titles and string->number->string
1956                         # conversion is not 1:1.
1957                         return "'" . $this->strencode( $s ) . "'";
1958                 }
1959         }
1960
1961         /**
1962          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1963          * MySQL uses `backticks` while basically everything else uses double quotes.
1964          * Since MySQL is the odd one out here the double quotes are our generic
1965          * and we implement backticks in DatabaseMysql.
1966          *
1967          * @param string $s
1968          * @return string
1969          */
1970         public function addIdentifierQuotes( $s ) {
1971                 return '"' . str_replace( '"', '""', $s ) . '"';
1972         }
1973
1974         /**
1975          * Returns if the given identifier looks quoted or not according to
1976          * the database convention for quoting identifiers .
1977          *
1978          * @note Do not use this to determine if untrusted input is safe.
1979          *   A malicious user can trick this function.
1980          * @param string $name
1981          * @return bool
1982          */
1983         public function isQuotedIdentifier( $name ) {
1984                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1985         }
1986
1987         /**
1988          * @param string $s
1989          * @return string
1990          */
1991         protected function escapeLikeInternal( $s ) {
1992                 return addcslashes( $s, '\%_' );
1993         }
1994
1995         public function buildLike() {
1996                 $params = func_get_args();
1997
1998                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1999                         $params = $params[0];
2000                 }
2001
2002                 $s = '';
2003
2004                 foreach ( $params as $value ) {
2005                         if ( $value instanceof LikeMatch ) {
2006                                 $s .= $value->toString();
2007                         } else {
2008                                 $s .= $this->escapeLikeInternal( $value );
2009                         }
2010                 }
2011
2012                 return " LIKE {$this->addQuotes( $s )} ";
2013         }
2014
2015         public function anyChar() {
2016                 return new LikeMatch( '_' );
2017         }
2018
2019         public function anyString() {
2020                 return new LikeMatch( '%' );
2021         }
2022
2023         public function nextSequenceValue( $seqName ) {
2024                 return null;
2025         }
2026
2027         /**
2028          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2029          * is only needed because a) MySQL must be as efficient as possible due to
2030          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2031          * which index to pick. Anyway, other databases might have different
2032          * indexes on a given table. So don't bother overriding this unless you're
2033          * MySQL.
2034          * @param string $index
2035          * @return string
2036          */
2037         public function useIndexClause( $index ) {
2038                 return '';
2039         }
2040
2041         /**
2042          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2043          * is only needed because a) MySQL must be as efficient as possible due to
2044          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2045          * which index to pick. Anyway, other databases might have different
2046          * indexes on a given table. So don't bother overriding this unless you're
2047          * MySQL.
2048          * @param string $index
2049          * @return string
2050          */
2051         public function ignoreIndexClause( $index ) {
2052                 return '';
2053         }
2054
2055         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2056                 $quotedTable = $this->tableName( $table );
2057
2058                 if ( count( $rows ) == 0 ) {
2059                         return;
2060                 }
2061
2062                 # Single row case
2063                 if ( !is_array( reset( $rows ) ) ) {
2064                         $rows = [ $rows ];
2065                 }
2066
2067                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2068                 foreach ( $rows as $row ) {
2069                         # Delete rows which collide
2070                         if ( $uniqueIndexes ) {
2071                                 $sql = "DELETE FROM $quotedTable WHERE ";
2072                                 $first = true;
2073                                 foreach ( $uniqueIndexes as $index ) {
2074                                         if ( $first ) {
2075                                                 $first = false;
2076                                                 $sql .= '( ';
2077                                         } else {
2078                                                 $sql .= ' ) OR ( ';
2079                                         }
2080                                         if ( is_array( $index ) ) {
2081                                                 $first2 = true;
2082                                                 foreach ( $index as $col ) {
2083                                                         if ( $first2 ) {
2084                                                                 $first2 = false;
2085                                                         } else {
2086                                                                 $sql .= ' AND ';
2087                                                         }
2088                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2089                                                 }
2090                                         } else {
2091                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2092                                         }
2093                                 }
2094                                 $sql .= ' )';
2095                                 $this->query( $sql, $fname );
2096                         }
2097
2098                         # Now insert the row
2099                         $this->insert( $table, $row, $fname );
2100                 }
2101         }
2102
2103         /**
2104          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2105          * statement.
2106          *
2107          * @param string $table Table name
2108          * @param array|string $rows Row(s) to insert
2109          * @param string $fname Caller function name
2110          *
2111          * @return ResultWrapper
2112          */
2113         protected function nativeReplace( $table, $rows, $fname ) {
2114                 $table = $this->tableName( $table );
2115
2116                 # Single row case
2117                 if ( !is_array( reset( $rows ) ) ) {
2118                         $rows = [ $rows ];
2119                 }
2120
2121                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2122                 $first = true;
2123
2124                 foreach ( $rows as $row ) {
2125                         if ( $first ) {
2126                                 $first = false;
2127                         } else {
2128                                 $sql .= ',';
2129                         }
2130
2131                         $sql .= '(' . $this->makeList( $row ) . ')';
2132                 }
2133
2134                 return $this->query( $sql, $fname );
2135         }
2136
2137         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2138                 $fname = __METHOD__
2139         ) {
2140                 if ( !count( $rows ) ) {
2141                         return true; // nothing to do
2142                 }
2143
2144                 if ( !is_array( reset( $rows ) ) ) {
2145                         $rows = [ $rows ];
2146                 }
2147
2148                 if ( count( $uniqueIndexes ) ) {
2149                         $clauses = []; // list WHERE clauses that each identify a single row
2150                         foreach ( $rows as $row ) {
2151                                 foreach ( $uniqueIndexes as $index ) {
2152                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2153                                         $rowKey = []; // unique key to this row
2154                                         foreach ( $index as $column ) {
2155                                                 $rowKey[$column] = $row[$column];
2156                                         }
2157                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2158                                 }
2159                         }
2160                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2161                 } else {
2162                         $where = false;
2163                 }
2164
2165                 $useTrx = !$this->mTrxLevel;
2166                 if ( $useTrx ) {
2167                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2168                 }
2169                 try {
2170                         # Update any existing conflicting row(s)
2171                         if ( $where !== false ) {
2172                                 $ok = $this->update( $table, $set, $where, $fname );
2173                         } else {
2174                                 $ok = true;
2175                         }
2176                         # Now insert any non-conflicting row(s)
2177                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2178                 } catch ( Exception $e ) {
2179                         if ( $useTrx ) {
2180                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2181                         }
2182                         throw $e;
2183                 }
2184                 if ( $useTrx ) {
2185                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2186                 }
2187
2188                 return $ok;
2189         }
2190
2191         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2192                 $fname = __METHOD__
2193         ) {
2194                 if ( !$conds ) {
2195                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2196                 }
2197
2198                 $delTable = $this->tableName( $delTable );
2199                 $joinTable = $this->tableName( $joinTable );
2200                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2201                 if ( $conds != '*' ) {
2202                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2203                 }
2204                 $sql .= ')';
2205
2206                 $this->query( $sql, $fname );
2207         }
2208
2209         /**
2210          * Returns the size of a text field, or -1 for "unlimited"
2211          *
2212          * @param string $table
2213          * @param string $field
2214          * @return int
2215          */
2216         public function textFieldSize( $table, $field ) {
2217                 $table = $this->tableName( $table );
2218                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2219                 $res = $this->query( $sql, __METHOD__ );
2220                 $row = $this->fetchObject( $res );
2221
2222                 $m = [];
2223
2224                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2225                         $size = $m[1];
2226                 } else {
2227                         $size = -1;
2228                 }
2229
2230                 return $size;
2231         }
2232
2233         public function delete( $table, $conds, $fname = __METHOD__ ) {
2234                 if ( !$conds ) {
2235                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2236                 }
2237
2238                 $table = $this->tableName( $table );
2239                 $sql = "DELETE FROM $table";
2240
2241                 if ( $conds != '*' ) {
2242                         if ( is_array( $conds ) ) {
2243                                 $conds = $this->makeList( $conds, LIST_AND );
2244                         }
2245                         $sql .= ' WHERE ' . $conds;
2246                 }
2247
2248                 return $this->query( $sql, $fname );
2249         }
2250
2251         public function insertSelect(
2252                 $destTable, $srcTable, $varMap, $conds,
2253                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2254         ) {
2255                 if ( $this->cliMode ) {
2256                         // For massive migrations with downtime, we don't want to select everything
2257                         // into memory and OOM, so do all this native on the server side if possible.
2258                         return $this->nativeInsertSelect(
2259                                 $destTable,
2260                                 $srcTable,
2261                                 $varMap,
2262                                 $conds,
2263                                 $fname,
2264                                 $insertOptions,
2265                                 $selectOptions
2266                         );
2267                 }
2268
2269                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2270                 // on only the master (without needing row-based-replication). It also makes it easy to
2271                 // know how big the INSERT is going to be.
2272                 $fields = [];
2273                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2274                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2275                 }
2276                 $selectOptions[] = 'FOR UPDATE';
2277                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2278                 if ( !$res ) {
2279                         return false;
2280                 }
2281
2282                 $rows = [];
2283                 foreach ( $res as $row ) {
2284                         $rows[] = (array)$row;
2285                 }
2286
2287                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2288         }
2289
2290         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2291                 $fname = __METHOD__,
2292                 $insertOptions = [], $selectOptions = []
2293         ) {
2294                 $destTable = $this->tableName( $destTable );
2295
2296                 if ( !is_array( $insertOptions ) ) {
2297                         $insertOptions = [ $insertOptions ];
2298                 }
2299
2300                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2301
2302                 if ( !is_array( $selectOptions ) ) {
2303                         $selectOptions = [ $selectOptions ];
2304                 }
2305
2306                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2307                         $selectOptions );
2308
2309                 if ( is_array( $srcTable ) ) {
2310                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2311                 } else {
2312                         $srcTable = $this->tableName( $srcTable );
2313                 }
2314
2315                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2316                         " SELECT $startOpts " . implode( ',', $varMap ) .
2317                         " FROM $srcTable $useIndex $ignoreIndex ";
2318
2319                 if ( $conds != '*' ) {
2320                         if ( is_array( $conds ) ) {
2321                                 $conds = $this->makeList( $conds, LIST_AND );
2322                         }
2323                         $sql .= " WHERE $conds";
2324                 }
2325
2326                 $sql .= " $tailOpts";
2327
2328                 return $this->query( $sql, $fname );
2329         }
2330
2331         /**
2332          * Construct a LIMIT query with optional offset. This is used for query
2333          * pages. The SQL should be adjusted so that only the first $limit rows
2334          * are returned. If $offset is provided as well, then the first $offset
2335          * rows should be discarded, and the next $limit rows should be returned.
2336          * If the result of the query is not ordered, then the rows to be returned
2337          * are theoretically arbitrary.
2338          *
2339          * $sql is expected to be a SELECT, if that makes a difference.
2340          *
2341          * The version provided by default works in MySQL and SQLite. It will very
2342          * likely need to be overridden for most other DBMSes.
2343          *
2344          * @param string $sql SQL query we will append the limit too
2345          * @param int $limit The SQL limit
2346          * @param int|bool $offset The SQL offset (default false)
2347          * @throws DBUnexpectedError
2348          * @return string
2349          */
2350         public function limitResult( $sql, $limit, $offset = false ) {
2351                 if ( !is_numeric( $limit ) ) {
2352                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2353                 }
2354
2355                 return "$sql LIMIT "
2356                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2357                 . "{$limit} ";
2358         }
2359
2360         public function unionSupportsOrderAndLimit() {
2361                 return true; // True for almost every DB supported
2362         }
2363
2364         public function unionQueries( $sqls, $all ) {
2365                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2366
2367                 return '(' . implode( $glue, $sqls ) . ')';
2368         }
2369
2370         public function conditional( $cond, $trueVal, $falseVal ) {
2371                 if ( is_array( $cond ) ) {
2372                         $cond = $this->makeList( $cond, LIST_AND );
2373                 }
2374
2375                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2376         }
2377
2378         public function strreplace( $orig, $old, $new ) {
2379                 return "REPLACE({$orig}, {$old}, {$new})";
2380         }
2381
2382         public function getServerUptime() {
2383                 return 0;
2384         }
2385
2386         public function wasDeadlock() {
2387                 return false;
2388         }
2389
2390         public function wasLockTimeout() {
2391                 return false;
2392         }
2393
2394         public function wasErrorReissuable() {
2395                 return false;
2396         }
2397
2398         public function wasReadOnlyError() {
2399                 return false;
2400         }
2401
2402         /**
2403          * Determines if the given query error was a connection drop
2404          * STUB
2405          *
2406          * @param integer|string $errno
2407          * @return bool
2408          */
2409         public function wasConnectionError( $errno ) {
2410                 return false;
2411         }
2412
2413         /**
2414          * Perform a deadlock-prone transaction.
2415          *
2416          * This function invokes a callback function to perform a set of write
2417          * queries. If a deadlock occurs during the processing, the transaction
2418          * will be rolled back and the callback function will be called again.
2419          *
2420          * Avoid using this method outside of Job or Maintenance classes.
2421          *
2422          * Usage:
2423          *   $dbw->deadlockLoop( callback, ... );
2424          *
2425          * Extra arguments are passed through to the specified callback function.
2426          * This method requires that no transactions are already active to avoid
2427          * causing premature commits or exceptions.
2428          *
2429          * Returns whatever the callback function returned on its successful,
2430          * iteration, or false on error, for example if the retry limit was
2431          * reached.
2432          *
2433          * @return mixed
2434          * @throws DBUnexpectedError
2435          * @throws Exception
2436          */
2437         public function deadlockLoop() {
2438                 $args = func_get_args();
2439                 $function = array_shift( $args );
2440                 $tries = self::DEADLOCK_TRIES;
2441
2442                 $this->begin( __METHOD__ );
2443
2444                 $retVal = null;
2445                 /** @var Exception $e */
2446                 $e = null;
2447                 do {
2448                         try {
2449                                 $retVal = call_user_func_array( $function, $args );
2450                                 break;
2451                         } catch ( DBQueryError $e ) {
2452                                 if ( $this->wasDeadlock() ) {
2453                                         // Retry after a randomized delay
2454                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2455                                 } else {
2456                                         // Throw the error back up
2457                                         throw $e;
2458                                 }
2459                         }
2460                 } while ( --$tries > 0 );
2461
2462                 if ( $tries <= 0 ) {
2463                         // Too many deadlocks; give up
2464                         $this->rollback( __METHOD__ );
2465                         throw $e;
2466                 } else {
2467                         $this->commit( __METHOD__ );
2468
2469                         return $retVal;
2470                 }
2471         }
2472
2473         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2474                 # Real waits are implemented in the subclass.
2475                 return 0;
2476         }
2477
2478         public function getSlavePos() {
2479                 # Stub
2480                 return false;
2481         }
2482
2483         public function getMasterPos() {
2484                 # Stub
2485                 return false;
2486         }
2487
2488         public function serverIsReadOnly() {
2489                 return false;
2490         }
2491
2492         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2493                 if ( !$this->mTrxLevel ) {
2494                         throw new DBUnexpectedError( $this, "No transaction is active." );
2495                 }
2496                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2497         }
2498
2499         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2500                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2501                 if ( !$this->mTrxLevel ) {
2502                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2503                 }
2504         }
2505
2506         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2507                 if ( $this->mTrxLevel ) {
2508                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2509                 } else {
2510                         // If no transaction is active, then make one for this callback
2511                         $this->startAtomic( __METHOD__ );
2512                         try {
2513                                 call_user_func( $callback );
2514                                 $this->endAtomic( __METHOD__ );
2515                         } catch ( Exception $e ) {
2516                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2517                                 throw $e;
2518                         }
2519                 }
2520         }
2521
2522         final public function setTransactionListener( $name, callable $callback = null ) {
2523                 if ( $callback ) {
2524                         $this->mTrxRecurringCallbacks[$name] = $callback;
2525                 } else {
2526                         unset( $this->mTrxRecurringCallbacks[$name] );
2527                 }
2528         }
2529
2530         /**
2531          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2532          *
2533          * This method should not be used outside of Database/LoadBalancer
2534          *
2535          * @param bool $suppress
2536          * @since 1.28
2537          */
2538         final public function setTrxEndCallbackSuppression( $suppress ) {
2539                 $this->mTrxEndCallbacksSuppressed = $suppress;
2540         }
2541
2542         /**
2543          * Actually run and consume any "on transaction idle/resolution" callbacks.
2544          *
2545          * This method should not be used outside of Database/LoadBalancer
2546          *
2547          * @param integer $trigger IDatabase::TRIGGER_* constant
2548          * @since 1.20
2549          * @throws Exception
2550          */
2551         public function runOnTransactionIdleCallbacks( $trigger ) {
2552                 if ( $this->mTrxEndCallbacksSuppressed ) {
2553                         return;
2554                 }
2555
2556                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2557                 /** @var Exception $e */
2558                 $e = null; // first exception
2559                 do { // callbacks may add callbacks :)
2560                         $callbacks = array_merge(
2561                                 $this->mTrxIdleCallbacks,
2562                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2563                         );
2564                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2565                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2566                         foreach ( $callbacks as $callback ) {
2567                                 try {
2568                                         list( $phpCallback ) = $callback;
2569                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2570                                         call_user_func_array( $phpCallback, [ $trigger ] );
2571                                         if ( $autoTrx ) {
2572                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2573                                         } else {
2574                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2575                                         }
2576                                 } catch ( Exception $ex ) {
2577                                         call_user_func( $this->errorLogger, $ex );
2578                                         $e = $e ?: $ex;
2579                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2580                                         // their transactions are ended so other callbacks don't fail
2581                                         if ( $this->trxLevel() ) {
2582                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2583                                         }
2584                                 }
2585                         }
2586                 } while ( count( $this->mTrxIdleCallbacks ) );
2587
2588                 if ( $e instanceof Exception ) {
2589                         throw $e; // re-throw any first exception
2590                 }
2591         }
2592
2593         /**
2594          * Actually run and consume any "on transaction pre-commit" callbacks.
2595          *
2596          * This method should not be used outside of Database/LoadBalancer
2597          *
2598          * @since 1.22
2599          * @throws Exception
2600          */
2601         public function runOnTransactionPreCommitCallbacks() {
2602                 $e = null; // first exception
2603                 do { // callbacks may add callbacks :)
2604                         $callbacks = $this->mTrxPreCommitCallbacks;
2605                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2606                         foreach ( $callbacks as $callback ) {
2607                                 try {
2608                                         list( $phpCallback ) = $callback;
2609                                         call_user_func( $phpCallback );
2610                                 } catch ( Exception $ex ) {
2611                                         call_user_func( $this->errorLogger, $ex );
2612                                         $e = $e ?: $ex;
2613                                 }
2614                         }
2615                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2616
2617                 if ( $e instanceof Exception ) {
2618                         throw $e; // re-throw any first exception
2619                 }
2620         }
2621
2622         /**
2623          * Actually run any "transaction listener" callbacks.
2624          *
2625          * This method should not be used outside of Database/LoadBalancer
2626          *
2627          * @param integer $trigger IDatabase::TRIGGER_* constant
2628          * @throws Exception
2629          * @since 1.20
2630          */
2631         public function runTransactionListenerCallbacks( $trigger ) {
2632                 if ( $this->mTrxEndCallbacksSuppressed ) {
2633                         return;
2634                 }
2635
2636                 /** @var Exception $e */
2637                 $e = null; // first exception
2638
2639                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2640                         try {
2641                                 $phpCallback( $trigger, $this );
2642                         } catch ( Exception $ex ) {
2643                                 call_user_func( $this->errorLogger, $ex );
2644                                 $e = $e ?: $ex;
2645                         }
2646                 }
2647
2648                 if ( $e instanceof Exception ) {
2649                         throw $e; // re-throw any first exception
2650                 }
2651         }
2652
2653         final public function startAtomic( $fname = __METHOD__ ) {
2654                 if ( !$this->mTrxLevel ) {
2655                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2656                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2657                         // in all changes being in one transaction to keep requests transactional.
2658                         if ( !$this->getFlag( DBO_TRX ) ) {
2659                                 $this->mTrxAutomaticAtomic = true;
2660                         }
2661                 }
2662
2663                 $this->mTrxAtomicLevels[] = $fname;
2664         }
2665
2666         final public function endAtomic( $fname = __METHOD__ ) {
2667                 if ( !$this->mTrxLevel ) {
2668                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2669                 }
2670                 if ( !$this->mTrxAtomicLevels ||
2671                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2672                 ) {
2673                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2674                 }
2675
2676                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2677                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2678                 }
2679         }
2680
2681         final public function doAtomicSection( $fname, callable $callback ) {
2682                 $this->startAtomic( $fname );
2683                 try {
2684                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2685                 } catch ( Exception $e ) {
2686                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2687                         throw $e;
2688                 }
2689                 $this->endAtomic( $fname );
2690
2691                 return $res;
2692         }
2693
2694         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2695                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2696                 if ( $this->mTrxLevel ) {
2697                         if ( $this->mTrxAtomicLevels ) {
2698                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2699                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2700                                 throw new DBUnexpectedError( $this, $msg );
2701                         } elseif ( !$this->mTrxAutomatic ) {
2702                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2703                                 throw new DBUnexpectedError( $this, $msg );
2704                         } else {
2705                                 // @TODO: make this an exception at some point
2706                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2707                                 $this->queryLogger->error( $msg );
2708                                 return; // join the main transaction set
2709                         }
2710                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2711                         // @TODO: make this an exception at some point
2712                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2713                         $this->queryLogger->error( $msg );
2714                         return; // let any writes be in the main transaction
2715                 }
2716
2717                 // Avoid fatals if close() was called
2718                 $this->assertOpen();
2719
2720                 $this->doBegin( $fname );
2721                 $this->mTrxTimestamp = microtime( true );
2722                 $this->mTrxFname = $fname;
2723                 $this->mTrxDoneWrites = false;
2724                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2725                 $this->mTrxAutomaticAtomic = false;
2726                 $this->mTrxAtomicLevels = [];
2727                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2728                 $this->mTrxWriteDuration = 0.0;
2729                 $this->mTrxWriteQueryCount = 0;
2730                 $this->mTrxWriteAdjDuration = 0.0;
2731                 $this->mTrxWriteAdjQueryCount = 0;
2732                 $this->mTrxWriteCallers = [];
2733                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2734                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2735                 // as lag itself just to be safe
2736                 $status = $this->getApproximateLagStatus();
2737                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2738         }
2739
2740         /**
2741          * Issues the BEGIN command to the database server.
2742          *
2743          * @see DatabaseBase::begin()
2744          * @param string $fname
2745          */
2746         protected function doBegin( $fname ) {
2747                 $this->query( 'BEGIN', $fname );
2748                 $this->mTrxLevel = 1;
2749         }
2750
2751         final public function commit( $fname = __METHOD__, $flush = '' ) {
2752                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2753                         // There are still atomic sections open. This cannot be ignored
2754                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2755                         throw new DBUnexpectedError(
2756                                 $this,
2757                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2758                         );
2759                 }
2760
2761                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2762                         if ( !$this->mTrxLevel ) {
2763                                 return; // nothing to do
2764                         } elseif ( !$this->mTrxAutomatic ) {
2765                                 throw new DBUnexpectedError(
2766                                         $this,
2767                                         "$fname: Flushing an explicit transaction, getting out of sync."
2768                                 );
2769                         }
2770                 } else {
2771                         if ( !$this->mTrxLevel ) {
2772                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2773                                 return; // nothing to do
2774                         } elseif ( $this->mTrxAutomatic ) {
2775                                 // @TODO: make this an exception at some point
2776                                 $msg = "$fname: Explicit commit of implicit transaction.";
2777                                 $this->queryLogger->error( $msg );
2778                                 return; // wait for the main transaction set commit round
2779                         }
2780                 }
2781
2782                 // Avoid fatals if close() was called
2783                 $this->assertOpen();
2784
2785                 $this->runOnTransactionPreCommitCallbacks();
2786                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2787                 $this->doCommit( $fname );
2788                 if ( $this->mTrxDoneWrites ) {
2789                         $this->mDoneWrites = microtime( true );
2790                         $this->trxProfiler->transactionWritingOut(
2791                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2792                 }
2793
2794                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2795                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2796         }
2797
2798         /**
2799          * Issues the COMMIT command to the database server.
2800          *
2801          * @see DatabaseBase::commit()
2802          * @param string $fname
2803          */
2804         protected function doCommit( $fname ) {
2805                 if ( $this->mTrxLevel ) {
2806                         $this->query( 'COMMIT', $fname );
2807                         $this->mTrxLevel = 0;
2808                 }
2809         }
2810
2811         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2812                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2813                         if ( !$this->mTrxLevel ) {
2814                                 return; // nothing to do
2815                         }
2816                 } else {
2817                         if ( !$this->mTrxLevel ) {
2818                                 $this->queryLogger->error(
2819                                         "$fname: No transaction to rollback, something got out of sync." );
2820                                 return; // nothing to do
2821                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2822                                 throw new DBUnexpectedError(
2823                                         $this,
2824                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2825                                 );
2826                         }
2827                 }
2828
2829                 // Avoid fatals if close() was called
2830                 $this->assertOpen();
2831
2832                 $this->doRollback( $fname );
2833                 $this->mTrxAtomicLevels = [];
2834                 if ( $this->mTrxDoneWrites ) {
2835                         $this->trxProfiler->transactionWritingOut(
2836                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2837                 }
2838
2839                 $this->mTrxIdleCallbacks = []; // clear
2840                 $this->mTrxPreCommitCallbacks = []; // clear
2841                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2842                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2843         }
2844
2845         /**
2846          * Issues the ROLLBACK command to the database server.
2847          *
2848          * @see DatabaseBase::rollback()
2849          * @param string $fname
2850          */
2851         protected function doRollback( $fname ) {
2852                 if ( $this->mTrxLevel ) {
2853                         # Disconnects cause rollback anyway, so ignore those errors
2854                         $ignoreErrors = true;
2855                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2856                         $this->mTrxLevel = 0;
2857                 }
2858         }
2859
2860         public function flushSnapshot( $fname = __METHOD__ ) {
2861                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2862                         // This only flushes transactions to clear snapshots, not to write data
2863                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2864                         throw new DBUnexpectedError(
2865                                 $this,
2866                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2867                         );
2868                 }
2869
2870                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2871         }
2872
2873         public function explicitTrxActive() {
2874                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2875         }
2876
2877         /**
2878          * Creates a new table with structure copied from existing table
2879          * Note that unlike most database abstraction functions, this function does not
2880          * automatically append database prefix, because it works at a lower
2881          * abstraction level.
2882          * The table names passed to this function shall not be quoted (this
2883          * function calls addIdentifierQuotes when needed).
2884          *
2885          * @param string $oldName Name of table whose structure should be copied
2886          * @param string $newName Name of table to be created
2887          * @param bool $temporary Whether the new table should be temporary
2888          * @param string $fname Calling function name
2889          * @throws RuntimeException
2890          * @return bool True if operation was successful
2891          */
2892         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2893                 $fname = __METHOD__
2894         ) {
2895                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2896         }
2897
2898         function listTables( $prefix = null, $fname = __METHOD__ ) {
2899                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2900         }
2901
2902         /**
2903          * Reset the views process cache set by listViews()
2904          * @since 1.22
2905          */
2906         final public function clearViewsCache() {
2907                 $this->allViews = null;
2908         }
2909
2910         /**
2911          * Lists all the VIEWs in the database
2912          *
2913          * For caching purposes the list of all views should be stored in
2914          * $this->allViews. The process cache can be cleared with clearViewsCache()
2915          *
2916          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2917          * @param string $fname Name of calling function
2918          * @throws RuntimeException
2919          * @return array
2920          * @since 1.22
2921          */
2922         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2923                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2924         }
2925
2926         /**
2927          * Differentiates between a TABLE and a VIEW
2928          *
2929          * @param string $name Name of the database-structure to test.
2930          * @throws RuntimeException
2931          * @return bool
2932          * @since 1.22
2933          */
2934         public function isView( $name ) {
2935                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2936         }
2937
2938         public function timestamp( $ts = 0 ) {
2939                 $t = new ConvertableTimestamp( $ts );
2940                 // Let errors bubble up to avoid putting garbage in the DB
2941                 return $t->getTimestamp( TS_MW );
2942         }
2943
2944         public function timestampOrNull( $ts = null ) {
2945                 if ( is_null( $ts ) ) {
2946                         return null;
2947                 } else {
2948                         return $this->timestamp( $ts );
2949                 }
2950         }
2951
2952         /**
2953          * Take the result from a query, and wrap it in a ResultWrapper if
2954          * necessary. Boolean values are passed through as is, to indicate success
2955          * of write queries or failure.
2956          *
2957          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2958          * resource, and it was necessary to call this function to convert it to
2959          * a wrapper. Nowadays, raw database objects are never exposed to external
2960          * callers, so this is unnecessary in external code.
2961          *
2962          * @param bool|ResultWrapper|resource|object $result
2963          * @return bool|ResultWrapper
2964          */
2965         protected function resultObject( $result ) {
2966                 if ( !$result ) {
2967                         return false;
2968                 } elseif ( $result instanceof ResultWrapper ) {
2969                         return $result;
2970                 } elseif ( $result === true ) {
2971                         // Successful write query
2972                         return $result;
2973                 } else {
2974                         return new ResultWrapper( $this, $result );
2975                 }
2976         }
2977
2978         public function ping( &$rtt = null ) {
2979                 // Avoid hitting the server if it was hit recently
2980                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2981                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2982                                 $rtt = $this->mRTTEstimate;
2983                                 return true; // don't care about $rtt
2984                         }
2985                 }
2986
2987                 // This will reconnect if possible or return false if not
2988                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
2989                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2990                 $this->restoreFlags( self::RESTORE_PRIOR );
2991
2992                 if ( $ok ) {
2993                         $rtt = $this->mRTTEstimate;
2994                 }
2995
2996                 return $ok;
2997         }
2998
2999         /**
3000          * @return bool
3001          */
3002         protected function reconnect() {
3003                 $this->closeConnection();
3004                 $this->mOpened = false;
3005                 $this->mConn = false;
3006                 try {
3007                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3008                         $this->lastPing = microtime( true );
3009                         $ok = true;
3010                 } catch ( DBConnectionError $e ) {
3011                         $ok = false;
3012                 }
3013
3014                 return $ok;
3015         }
3016
3017         public function getSessionLagStatus() {
3018                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3019         }
3020
3021         /**
3022          * Get the replica DB lag when the current transaction started
3023          *
3024          * This is useful when transactions might use snapshot isolation
3025          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3026          * is this lag plus transaction duration. If they don't, it is still
3027          * safe to be pessimistic. This returns null if there is no transaction.
3028          *
3029          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3030          * @since 1.27
3031          */
3032         public function getTransactionLagStatus() {
3033                 return $this->mTrxLevel
3034                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3035                         : null;
3036         }
3037
3038         /**
3039          * Get a replica DB lag estimate for this server
3040          *
3041          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3042          * @since 1.27
3043          */
3044         public function getApproximateLagStatus() {
3045                 return [
3046                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3047                         'since' => microtime( true )
3048                 ];
3049         }
3050
3051         /**
3052          * Merge the result of getSessionLagStatus() for several DBs
3053          * using the most pessimistic values to estimate the lag of
3054          * any data derived from them in combination
3055          *
3056          * This is information is useful for caching modules
3057          *
3058          * @see WANObjectCache::set()
3059          * @see WANObjectCache::getWithSetCallback()
3060          *
3061          * @param IDatabase $db1
3062          * @param IDatabase ...
3063          * @return array Map of values:
3064          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3065          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3066          *   - pending: whether any of the DBs have uncommitted changes
3067          * @since 1.27
3068          */
3069         public static function getCacheSetOptions( IDatabase $db1 ) {
3070                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3071                 foreach ( func_get_args() as $db ) {
3072                         /** @var IDatabase $db */
3073                         $status = $db->getSessionLagStatus();
3074                         if ( $status['lag'] === false ) {
3075                                 $res['lag'] = false;
3076                         } elseif ( $res['lag'] !== false ) {
3077                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3078                         }
3079                         $res['since'] = min( $res['since'], $status['since'] );
3080                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3081                 }
3082
3083                 return $res;
3084         }
3085
3086         public function getLag() {
3087                 return 0;
3088         }
3089
3090         function maxListLen() {
3091                 return 0;
3092         }
3093
3094         public function encodeBlob( $b ) {
3095                 return $b;
3096         }
3097
3098         public function decodeBlob( $b ) {
3099                 if ( $b instanceof Blob ) {
3100                         $b = $b->fetch();
3101                 }
3102                 return $b;
3103         }
3104
3105         public function setSessionOptions( array $options ) {
3106         }
3107
3108         /**
3109          * Read and execute SQL commands from a file.
3110          *
3111          * Returns true on success, error string or exception on failure (depending
3112          * on object's error ignore settings).
3113          *
3114          * @param string $filename File name to open
3115          * @param bool|callable $lineCallback Optional function called before reading each line
3116          * @param bool|callable $resultCallback Optional function called for each MySQL result
3117          * @param bool|string $fname Calling function name or false if name should be
3118          *   generated dynamically using $filename
3119          * @param bool|callable $inputCallback Optional function called for each
3120          *   complete line sent
3121          * @return bool|string
3122          * @throws Exception
3123          */
3124         public function sourceFile(
3125                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3126         ) {
3127                 MediaWiki\suppressWarnings();
3128                 $fp = fopen( $filename, 'r' );
3129                 MediaWiki\restoreWarnings();
3130
3131                 if ( false === $fp ) {
3132                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3133                 }
3134
3135                 if ( !$fname ) {
3136                         $fname = __METHOD__ . "( $filename )";
3137                 }
3138
3139                 try {
3140                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3141                 } catch ( Exception $e ) {
3142                         fclose( $fp );
3143                         throw $e;
3144                 }
3145
3146                 fclose( $fp );
3147
3148                 return $error;
3149         }
3150
3151         public function setSchemaVars( $vars ) {
3152                 $this->mSchemaVars = $vars;
3153         }
3154
3155         /**
3156          * Read and execute commands from an open file handle.
3157          *
3158          * Returns true on success, error string or exception on failure (depending
3159          * on object's error ignore settings).
3160          *
3161          * @param resource $fp File handle
3162          * @param bool|callable $lineCallback Optional function called before reading each query
3163          * @param bool|callable $resultCallback Optional function called for each MySQL result
3164          * @param string $fname Calling function name
3165          * @param bool|callable $inputCallback Optional function called for each complete query sent
3166          * @return bool|string
3167          */
3168         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3169                 $fname = __METHOD__, $inputCallback = false
3170         ) {
3171                 $cmd = '';
3172
3173                 while ( !feof( $fp ) ) {
3174                         if ( $lineCallback ) {
3175                                 call_user_func( $lineCallback );
3176                         }
3177
3178                         $line = trim( fgets( $fp ) );
3179
3180                         if ( $line == '' ) {
3181                                 continue;
3182                         }
3183
3184                         if ( '-' == $line[0] && '-' == $line[1] ) {
3185                                 continue;
3186                         }
3187
3188                         if ( $cmd != '' ) {
3189                                 $cmd .= ' ';
3190                         }
3191
3192                         $done = $this->streamStatementEnd( $cmd, $line );
3193
3194                         $cmd .= "$line\n";
3195
3196                         if ( $done || feof( $fp ) ) {
3197                                 $cmd = $this->replaceVars( $cmd );
3198
3199                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3200                                         $res = $this->query( $cmd, $fname );
3201
3202                                         if ( $resultCallback ) {
3203                                                 call_user_func( $resultCallback, $res, $this );
3204                                         }
3205
3206                                         if ( false === $res ) {
3207                                                 $err = $this->lastError();
3208
3209                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3210                                         }
3211                                 }
3212                                 $cmd = '';
3213                         }
3214                 }
3215
3216                 return true;
3217         }
3218
3219         /**
3220          * Called by sourceStream() to check if we've reached a statement end
3221          *
3222          * @param string $sql SQL assembled so far
3223          * @param string $newLine New line about to be added to $sql
3224          * @return bool Whether $newLine contains end of the statement
3225          */
3226         public function streamStatementEnd( &$sql, &$newLine ) {
3227                 if ( $this->delimiter ) {
3228                         $prev = $newLine;
3229                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3230                         if ( $newLine != $prev ) {
3231                                 return true;
3232                         }
3233                 }
3234
3235                 return false;
3236         }
3237
3238         /**
3239          * Database independent variable replacement. Replaces a set of variables
3240          * in an SQL statement with their contents as given by $this->getSchemaVars().
3241          *
3242          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3243          *
3244          * - '{$var}' should be used for text and is passed through the database's
3245          *   addQuotes method.
3246          * - `{$var}` should be used for identifiers (e.g. table and database names).
3247          *   It is passed through the database's addIdentifierQuotes method which
3248          *   can be overridden if the database uses something other than backticks.
3249          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3250          *   database's tableName method.
3251          * - / *i* / passes the name that follows through the database's indexName method.
3252          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3253          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3254          *
3255          * @param string $ins SQL statement to replace variables in
3256          * @return string The new SQL statement with variables replaced
3257          */
3258         protected function replaceVars( $ins ) {
3259                 $vars = $this->getSchemaVars();
3260                 return preg_replace_callback(
3261                         '!
3262                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3263                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3264                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3265                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3266                         !x',
3267                         function ( $m ) use ( $vars ) {
3268                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3269                                 // check for both nonexistent keys *and* the empty string.
3270                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3271                                         if ( $m[1] === 'i' ) {
3272                                                 return $this->indexName( $m[2] );
3273                                         } else {
3274                                                 return $this->tableName( $m[2] );
3275                                         }
3276                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3277                                         return $this->addQuotes( $vars[$m[3]] );
3278                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3279                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3280                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3281                                         return $vars[$m[5]];
3282                                 } else {
3283                                         return $m[0];
3284                                 }
3285                         },
3286                         $ins
3287                 );
3288         }
3289
3290         /**
3291          * Get schema variables. If none have been set via setSchemaVars(), then
3292          * use some defaults from the current object.
3293          *
3294          * @return array
3295          */
3296         protected function getSchemaVars() {
3297                 if ( $this->mSchemaVars ) {
3298                         return $this->mSchemaVars;
3299                 } else {
3300                         return $this->getDefaultSchemaVars();
3301                 }
3302         }
3303
3304         /**
3305          * Get schema variables to use if none have been set via setSchemaVars().
3306          *
3307          * Override this in derived classes to provide variables for tables.sql
3308          * and SQL patch files.
3309          *
3310          * @return array
3311          */
3312         protected function getDefaultSchemaVars() {
3313                 return [];
3314         }
3315
3316         public function lockIsFree( $lockName, $method ) {
3317                 return true;
3318         }
3319
3320         public function lock( $lockName, $method, $timeout = 5 ) {
3321                 $this->mNamedLocksHeld[$lockName] = 1;
3322
3323                 return true;
3324         }
3325
3326         public function unlock( $lockName, $method ) {
3327                 unset( $this->mNamedLocksHeld[$lockName] );
3328
3329                 return true;
3330         }
3331
3332         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3333                 if ( $this->writesOrCallbacksPending() ) {
3334                         // This only flushes transactions to clear snapshots, not to write data
3335                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3336                         throw new DBUnexpectedError(
3337                                 $this,
3338                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3339                         );
3340                 }
3341
3342                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3343                         return null;
3344                 }
3345
3346                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3347                         if ( $this->trxLevel() ) {
3348                                 // There is a good chance an exception was thrown, causing any early return
3349                                 // from the caller. Let any error handler get a chance to issue rollback().
3350                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3351                                 $this->onTransactionResolution(
3352                                         function () use ( $lockKey, $fname ) {
3353                                                 $this->unlock( $lockKey, $fname );
3354                                         },
3355                                         $fname
3356                                 );
3357                         } else {
3358                                 $this->unlock( $lockKey, $fname );
3359                         }
3360                 } );
3361
3362                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3363
3364                 return $unlocker;
3365         }
3366
3367         public function namedLocksEnqueue() {
3368                 return false;
3369         }
3370
3371         /**
3372          * Lock specific tables
3373          *
3374          * @param array $read Array of tables to lock for read access
3375          * @param array $write Array of tables to lock for write access
3376          * @param string $method Name of caller
3377          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3378          * @return bool
3379          */
3380         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3381                 return true;
3382         }
3383
3384         /**
3385          * Unlock specific tables
3386          *
3387          * @param string $method The caller
3388          * @return bool
3389          */
3390         public function unlockTables( $method ) {
3391                 return true;
3392         }
3393
3394         /**
3395          * Delete a table
3396          * @param string $tableName
3397          * @param string $fName
3398          * @return bool|ResultWrapper
3399          * @since 1.18
3400          */
3401         public function dropTable( $tableName, $fName = __METHOD__ ) {
3402                 if ( !$this->tableExists( $tableName, $fName ) ) {
3403                         return false;
3404                 }
3405                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3406
3407                 return $this->query( $sql, $fName );
3408         }
3409
3410         public function getInfinity() {
3411                 return 'infinity';
3412         }
3413
3414         public function encodeExpiry( $expiry ) {
3415                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3416                         ? $this->getInfinity()
3417                         : $this->timestamp( $expiry );
3418         }
3419
3420         public function decodeExpiry( $expiry, $format = TS_MW ) {
3421                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3422                         return 'infinity';
3423                 }
3424
3425                 try {
3426                         $t = new ConvertableTimestamp( $expiry );
3427
3428                         return $t->getTimestamp( $format );
3429                 } catch ( TimestampException $e ) {
3430                         return false;
3431                 }
3432         }
3433
3434         public function setBigSelects( $value = true ) {
3435                 // no-op
3436         }
3437
3438         public function isReadOnly() {
3439                 return ( $this->getReadOnlyReason() !== false );
3440         }
3441
3442         /**
3443          * @return string|bool Reason this DB is read-only or false if it is not
3444          */
3445         protected function getReadOnlyReason() {
3446                 $reason = $this->getLBInfo( 'readOnlyReason' );
3447
3448                 return is_string( $reason ) ? $reason : false;
3449         }
3450
3451         public function setTableAliases( array $aliases ) {
3452                 $this->tableAliases = $aliases;
3453         }
3454
3455         /**
3456          * @since 1.19
3457          * @return string
3458          */
3459         public function __toString() {
3460                 return (string)$this->mConn;
3461         }
3462
3463         /**
3464          * Called by serialize. Throw an exception when DB connection is serialized.
3465          * This causes problems on some database engines because the connection is
3466          * not restored on unserialize.
3467          */
3468         public function __sleep() {
3469                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3470                         'the connection is not restored on wakeup.' );
3471         }
3472
3473         /**
3474          * Run a few simple sanity checks
3475          */
3476         public function __destruct() {
3477                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3478                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3479                 }
3480
3481                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3482                 if ( $danglingWriters ) {
3483                         $fnames = implode( ', ', $danglingWriters );
3484                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3485                 }
3486         }
3487 }