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