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'], self::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, self::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, self::LIST_SET );
1471
1472                 if ( $conds !== [] && $conds !== '*' ) {
1473                         $sql .= " WHERE " . $this->makeList( $conds, self::LIST_AND );
1474                 }
1475
1476                 return $this->query( $sql, $fname );
1477         }
1478
1479         public function makeList( $a, $mode = self::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 == self::LIST_AND ) {
1490                                         $list .= ' AND ';
1491                                 } elseif ( $mode == self::LIST_OR ) {
1492                                         $list .= ' OR ';
1493                                 } else {
1494                                         $list .= ',';
1495                                 }
1496                         } else {
1497                                 $first = false;
1498                         }
1499
1500                         if ( ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_numeric( $field ) ) {
1501                                 $list .= "($value)";
1502                         } elseif ( $mode == self::LIST_SET && is_numeric( $field ) ) {
1503                                 $list .= "$value";
1504                         } elseif (
1505                                 ( $mode == self::LIST_AND || $mode == self::LIST_OR ) && is_array( $value )
1506                         ) {
1507                                 // Remove null from array to be handled separately if found
1508                                 $includeNull = false;
1509                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1510                                         $includeNull = true;
1511                                         unset( $value[$nullKey] );
1512                                 }
1513                                 if ( count( $value ) == 0 && !$includeNull ) {
1514                                         throw new InvalidArgumentException(
1515                                                 __METHOD__ . ": empty input for field $field" );
1516                                 } elseif ( count( $value ) == 0 ) {
1517                                         // only check if $field is null
1518                                         $list .= "$field IS NULL";
1519                                 } else {
1520                                         // IN clause contains at least one valid element
1521                                         if ( $includeNull ) {
1522                                                 // Group subconditions to ensure correct precedence
1523                                                 $list .= '(';
1524                                         }
1525                                         if ( count( $value ) == 1 ) {
1526                                                 // Special-case single values, as IN isn't terribly efficient
1527                                                 // Don't necessarily assume the single key is 0; we don't
1528                                                 // enforce linear numeric ordering on other arrays here.
1529                                                 $value = array_values( $value )[0];
1530                                                 $list .= $field . " = " . $this->addQuotes( $value );
1531                                         } else {
1532                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1533                                         }
1534                                         // if null present in array, append IS NULL
1535                                         if ( $includeNull ) {
1536                                                 $list .= " OR $field IS NULL)";
1537                                         }
1538                                 }
1539                         } elseif ( $value === null ) {
1540                                 if ( $mode == self::LIST_AND || $mode == self::LIST_OR ) {
1541                                         $list .= "$field IS ";
1542                                 } elseif ( $mode == self::LIST_SET ) {
1543                                         $list .= "$field = ";
1544                                 }
1545                                 $list .= 'NULL';
1546                         } else {
1547                                 if (
1548                                         $mode == self::LIST_AND || $mode == self::LIST_OR || $mode == self::LIST_SET
1549                                 ) {
1550                                         $list .= "$field = ";
1551                                 }
1552                                 $list .= $mode == self::LIST_NAMES ? $value : $this->addQuotes( $value );
1553                         }
1554                 }
1555
1556                 return $list;
1557         }
1558
1559         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1560                 $conds = [];
1561
1562                 foreach ( $data as $base => $sub ) {
1563                         if ( count( $sub ) ) {
1564                                 $conds[] = $this->makeList(
1565                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1566                                         self::LIST_AND );
1567                         }
1568                 }
1569
1570                 if ( $conds ) {
1571                         return $this->makeList( $conds, self::LIST_OR );
1572                 } else {
1573                         // Nothing to search for...
1574                         return false;
1575                 }
1576         }
1577
1578         /**
1579          * Return aggregated value alias
1580          *
1581          * @param array $valuedata
1582          * @param string $valuename
1583          *
1584          * @return string
1585          */
1586         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1587                 return $valuename;
1588         }
1589
1590         public function bitNot( $field ) {
1591                 return "(~$field)";
1592         }
1593
1594         public function bitAnd( $fieldLeft, $fieldRight ) {
1595                 return "($fieldLeft & $fieldRight)";
1596         }
1597
1598         public function bitOr( $fieldLeft, $fieldRight ) {
1599                 return "($fieldLeft | $fieldRight)";
1600         }
1601
1602         public function buildConcat( $stringList ) {
1603                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1604         }
1605
1606         public function buildGroupConcatField(
1607                 $delim, $table, $field, $conds = '', $join_conds = []
1608         ) {
1609                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1610
1611                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1612         }
1613
1614         /**
1615          * @param string $field Field or column to cast
1616          * @return string
1617          * @since 1.28
1618          */
1619         public function buildStringCast( $field ) {
1620                 return $field;
1621         }
1622
1623         public function selectDB( $db ) {
1624                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1625                 # if your database engine supports a concept similar to MySQL's
1626                 # databases you may as well.
1627                 $this->mDBname = $db;
1628
1629                 return true;
1630         }
1631
1632         public function getDBname() {
1633                 return $this->mDBname;
1634         }
1635
1636         public function getServer() {
1637                 return $this->mServer;
1638         }
1639
1640         /**
1641          * Format a table name ready for use in constructing an SQL query
1642          *
1643          * This does two important things: it quotes the table names to clean them up,
1644          * and it adds a table prefix if only given a table name with no quotes.
1645          *
1646          * All functions of this object which require a table name call this function
1647          * themselves. Pass the canonical name to such functions. This is only needed
1648          * when calling query() directly.
1649          *
1650          * @note This function does not sanitize user input. It is not safe to use
1651          *   this function to escape user input.
1652          * @param string $name Database table name
1653          * @param string $format One of:
1654          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1655          *            so that it can be used in a query.
1656          *   raw - Do not add identifier quotes to the table name
1657          * @return string Full database name
1658          */
1659         public function tableName( $name, $format = 'quoted' ) {
1660                 # Skip the entire process when we have a string quoted on both ends.
1661                 # Note that we check the end so that we will still quote any use of
1662                 # use of `database`.table. But won't break things if someone wants
1663                 # to query a database table with a dot in the name.
1664                 if ( $this->isQuotedIdentifier( $name ) ) {
1665                         return $name;
1666                 }
1667
1668                 # Lets test for any bits of text that should never show up in a table
1669                 # name. Basically anything like JOIN or ON which are actually part of
1670                 # SQL queries, but may end up inside of the table value to combine
1671                 # sql. Such as how the API is doing.
1672                 # Note that we use a whitespace test rather than a \b test to avoid
1673                 # any remote case where a word like on may be inside of a table name
1674                 # surrounded by symbols which may be considered word breaks.
1675                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1676                         return $name;
1677                 }
1678
1679                 # Split database and table into proper variables.
1680                 # We reverse the explode so that database.table and table both output
1681                 # the correct table.
1682                 $dbDetails = explode( '.', $name, 3 );
1683                 if ( count( $dbDetails ) == 3 ) {
1684                         list( $database, $schema, $table ) = $dbDetails;
1685                         # We don't want any prefix added in this case
1686                         $prefix = '';
1687                 } elseif ( count( $dbDetails ) == 2 ) {
1688                         list( $database, $table ) = $dbDetails;
1689                         # We don't want any prefix added in this case
1690                         # In dbs that support it, $database may actually be the schema
1691                         # but that doesn't affect any of the functionality here
1692                         $prefix = '';
1693                         $schema = '';
1694                 } else {
1695                         list( $table ) = $dbDetails;
1696                         if ( isset( $this->tableAliases[$table] ) ) {
1697                                 $database = $this->tableAliases[$table]['dbname'];
1698                                 $schema = is_string( $this->tableAliases[$table]['schema'] )
1699                                         ? $this->tableAliases[$table]['schema']
1700                                         : $this->mSchema;
1701                                 $prefix = is_string( $this->tableAliases[$table]['prefix'] )
1702                                         ? $this->tableAliases[$table]['prefix']
1703                                         : $this->mTablePrefix;
1704                         } else {
1705                                 $database = '';
1706                                 $schema = $this->mSchema; # Default schema
1707                                 $prefix = $this->mTablePrefix; # Default prefix
1708                         }
1709                 }
1710
1711                 # Quote $table and apply the prefix if not quoted.
1712                 # $tableName might be empty if this is called from Database::replaceVars()
1713                 $tableName = "{$prefix}{$table}";
1714                 if ( $format == 'quoted'
1715                         && !$this->isQuotedIdentifier( $tableName ) && $tableName !== ''
1716                 ) {
1717                         $tableName = $this->addIdentifierQuotes( $tableName );
1718                 }
1719
1720                 # Quote $schema and merge it with the table name if needed
1721                 if ( strlen( $schema ) ) {
1722                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1723                                 $schema = $this->addIdentifierQuotes( $schema );
1724                         }
1725                         $tableName = $schema . '.' . $tableName;
1726                 }
1727
1728                 # Quote $database and merge it with the table name if needed
1729                 if ( $database !== '' ) {
1730                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1731                                 $database = $this->addIdentifierQuotes( $database );
1732                         }
1733                         $tableName = $database . '.' . $tableName;
1734                 }
1735
1736                 return $tableName;
1737         }
1738
1739         /**
1740          * Fetch a number of table names into an array
1741          * This is handy when you need to construct SQL for joins
1742          *
1743          * Example:
1744          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1745          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1746          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1747          *
1748          * @return array
1749          */
1750         public function tableNames() {
1751                 $inArray = func_get_args();
1752                 $retVal = [];
1753
1754                 foreach ( $inArray as $name ) {
1755                         $retVal[$name] = $this->tableName( $name );
1756                 }
1757
1758                 return $retVal;
1759         }
1760
1761         /**
1762          * Fetch a number of table names into an zero-indexed numerical array
1763          * This is handy when you need to construct SQL for joins
1764          *
1765          * Example:
1766          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1767          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1768          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1769          *
1770          * @return array
1771          */
1772         public function tableNamesN() {
1773                 $inArray = func_get_args();
1774                 $retVal = [];
1775
1776                 foreach ( $inArray as $name ) {
1777                         $retVal[] = $this->tableName( $name );
1778                 }
1779
1780                 return $retVal;
1781         }
1782
1783         /**
1784          * Get an aliased table name
1785          * e.g. tableName AS newTableName
1786          *
1787          * @param string $name Table name, see tableName()
1788          * @param string|bool $alias Alias (optional)
1789          * @return string SQL name for aliased table. Will not alias a table to its own name
1790          */
1791         public function tableNameWithAlias( $name, $alias = false ) {
1792                 if ( !$alias || $alias == $name ) {
1793                         return $this->tableName( $name );
1794                 } else {
1795                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1796                 }
1797         }
1798
1799         /**
1800          * Gets an array of aliased table names
1801          *
1802          * @param array $tables [ [alias] => table ]
1803          * @return string[] See tableNameWithAlias()
1804          */
1805         public function tableNamesWithAlias( $tables ) {
1806                 $retval = [];
1807                 foreach ( $tables as $alias => $table ) {
1808                         if ( is_numeric( $alias ) ) {
1809                                 $alias = $table;
1810                         }
1811                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1812                 }
1813
1814                 return $retval;
1815         }
1816
1817         /**
1818          * Get an aliased field name
1819          * e.g. fieldName AS newFieldName
1820          *
1821          * @param string $name Field name
1822          * @param string|bool $alias Alias (optional)
1823          * @return string SQL name for aliased field. Will not alias a field to its own name
1824          */
1825         public function fieldNameWithAlias( $name, $alias = false ) {
1826                 if ( !$alias || (string)$alias === (string)$name ) {
1827                         return $name;
1828                 } else {
1829                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1830                 }
1831         }
1832
1833         /**
1834          * Gets an array of aliased field names
1835          *
1836          * @param array $fields [ [alias] => field ]
1837          * @return string[] See fieldNameWithAlias()
1838          */
1839         public function fieldNamesWithAlias( $fields ) {
1840                 $retval = [];
1841                 foreach ( $fields as $alias => $field ) {
1842                         if ( is_numeric( $alias ) ) {
1843                                 $alias = $field;
1844                         }
1845                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1846                 }
1847
1848                 return $retval;
1849         }
1850
1851         /**
1852          * Get the aliased table name clause for a FROM clause
1853          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
1854          *
1855          * @param array $tables ( [alias] => table )
1856          * @param array $use_index Same as for select()
1857          * @param array $ignore_index Same as for select()
1858          * @param array $join_conds Same as for select()
1859          * @return string
1860          */
1861         protected function tableNamesWithIndexClauseOrJOIN(
1862                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
1863         ) {
1864                 $ret = [];
1865                 $retJOIN = [];
1866                 $use_index = (array)$use_index;
1867                 $ignore_index = (array)$ignore_index;
1868                 $join_conds = (array)$join_conds;
1869
1870                 foreach ( $tables as $alias => $table ) {
1871                         if ( !is_string( $alias ) ) {
1872                                 // No alias? Set it equal to the table name
1873                                 $alias = $table;
1874                         }
1875                         // Is there a JOIN clause for this table?
1876                         if ( isset( $join_conds[$alias] ) ) {
1877                                 list( $joinType, $conds ) = $join_conds[$alias];
1878                                 $tableClause = $joinType;
1879                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1880                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1881                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1882                                         if ( $use != '' ) {
1883                                                 $tableClause .= ' ' . $use;
1884                                         }
1885                                 }
1886                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
1887                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
1888                                         if ( $ignore != '' ) {
1889                                                 $tableClause .= ' ' . $ignore;
1890                                         }
1891                                 }
1892                                 $on = $this->makeList( (array)$conds, self::LIST_AND );
1893                                 if ( $on != '' ) {
1894                                         $tableClause .= ' ON (' . $on . ')';
1895                                 }
1896
1897                                 $retJOIN[] = $tableClause;
1898                         } elseif ( isset( $use_index[$alias] ) ) {
1899                                 // Is there an INDEX clause for this table?
1900                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1901                                 $tableClause .= ' ' . $this->useIndexClause(
1902                                                 implode( ',', (array)$use_index[$alias] )
1903                                         );
1904
1905                                 $ret[] = $tableClause;
1906                         } elseif ( isset( $ignore_index[$alias] ) ) {
1907                                 // Is there an INDEX clause for this table?
1908                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1909                                 $tableClause .= ' ' . $this->ignoreIndexClause(
1910                                                 implode( ',', (array)$ignore_index[$alias] )
1911                                         );
1912
1913                                 $ret[] = $tableClause;
1914                         } else {
1915                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1916
1917                                 $ret[] = $tableClause;
1918                         }
1919                 }
1920
1921                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1922                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1923                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1924
1925                 // Compile our final table clause
1926                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1927         }
1928
1929         /**
1930          * Get the name of an index in a given table.
1931          *
1932          * @param string $index
1933          * @return string
1934          */
1935         protected function indexName( $index ) {
1936                 // Backwards-compatibility hack
1937                 $renamed = [
1938                         'ar_usertext_timestamp' => 'usertext_timestamp',
1939                         'un_user_id' => 'user_id',
1940                         'un_user_ip' => 'user_ip',
1941                 ];
1942
1943                 if ( isset( $renamed[$index] ) ) {
1944                         return $renamed[$index];
1945                 } else {
1946                         return $index;
1947                 }
1948         }
1949
1950         public function addQuotes( $s ) {
1951                 if ( $s instanceof Blob ) {
1952                         $s = $s->fetch();
1953                 }
1954                 if ( $s === null ) {
1955                         return 'NULL';
1956                 } else {
1957                         # This will also quote numeric values. This should be harmless,
1958                         # and protects against weird problems that occur when they really
1959                         # _are_ strings such as article titles and string->number->string
1960                         # conversion is not 1:1.
1961                         return "'" . $this->strencode( $s ) . "'";
1962                 }
1963         }
1964
1965         /**
1966          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1967          * MySQL uses `backticks` while basically everything else uses double quotes.
1968          * Since MySQL is the odd one out here the double quotes are our generic
1969          * and we implement backticks in DatabaseMysql.
1970          *
1971          * @param string $s
1972          * @return string
1973          */
1974         public function addIdentifierQuotes( $s ) {
1975                 return '"' . str_replace( '"', '""', $s ) . '"';
1976         }
1977
1978         /**
1979          * Returns if the given identifier looks quoted or not according to
1980          * the database convention for quoting identifiers .
1981          *
1982          * @note Do not use this to determine if untrusted input is safe.
1983          *   A malicious user can trick this function.
1984          * @param string $name
1985          * @return bool
1986          */
1987         public function isQuotedIdentifier( $name ) {
1988                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1989         }
1990
1991         /**
1992          * @param string $s
1993          * @return string
1994          */
1995         protected function escapeLikeInternal( $s ) {
1996                 return addcslashes( $s, '\%_' );
1997         }
1998
1999         public function buildLike() {
2000                 $params = func_get_args();
2001
2002                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2003                         $params = $params[0];
2004                 }
2005
2006                 $s = '';
2007
2008                 foreach ( $params as $value ) {
2009                         if ( $value instanceof LikeMatch ) {
2010                                 $s .= $value->toString();
2011                         } else {
2012                                 $s .= $this->escapeLikeInternal( $value );
2013                         }
2014                 }
2015
2016                 return " LIKE {$this->addQuotes( $s )} ";
2017         }
2018
2019         public function anyChar() {
2020                 return new LikeMatch( '_' );
2021         }
2022
2023         public function anyString() {
2024                 return new LikeMatch( '%' );
2025         }
2026
2027         public function nextSequenceValue( $seqName ) {
2028                 return null;
2029         }
2030
2031         /**
2032          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2033          * is only needed because a) MySQL must be as efficient as possible due to
2034          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2035          * which index to pick. Anyway, other databases might have different
2036          * indexes on a given table. So don't bother overriding this unless you're
2037          * MySQL.
2038          * @param string $index
2039          * @return string
2040          */
2041         public function useIndexClause( $index ) {
2042                 return '';
2043         }
2044
2045         /**
2046          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2047          * is only needed because a) MySQL must be as efficient as possible due to
2048          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2049          * which index to pick. Anyway, other databases might have different
2050          * indexes on a given table. So don't bother overriding this unless you're
2051          * MySQL.
2052          * @param string $index
2053          * @return string
2054          */
2055         public function ignoreIndexClause( $index ) {
2056                 return '';
2057         }
2058
2059         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2060                 $quotedTable = $this->tableName( $table );
2061
2062                 if ( count( $rows ) == 0 ) {
2063                         return;
2064                 }
2065
2066                 # Single row case
2067                 if ( !is_array( reset( $rows ) ) ) {
2068                         $rows = [ $rows ];
2069                 }
2070
2071                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2072                 foreach ( $rows as $row ) {
2073                         # Delete rows which collide
2074                         if ( $uniqueIndexes ) {
2075                                 $sql = "DELETE FROM $quotedTable WHERE ";
2076                                 $first = true;
2077                                 foreach ( $uniqueIndexes as $index ) {
2078                                         if ( $first ) {
2079                                                 $first = false;
2080                                                 $sql .= '( ';
2081                                         } else {
2082                                                 $sql .= ' ) OR ( ';
2083                                         }
2084                                         if ( is_array( $index ) ) {
2085                                                 $first2 = true;
2086                                                 foreach ( $index as $col ) {
2087                                                         if ( $first2 ) {
2088                                                                 $first2 = false;
2089                                                         } else {
2090                                                                 $sql .= ' AND ';
2091                                                         }
2092                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2093                                                 }
2094                                         } else {
2095                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2096                                         }
2097                                 }
2098                                 $sql .= ' )';
2099                                 $this->query( $sql, $fname );
2100                         }
2101
2102                         # Now insert the row
2103                         $this->insert( $table, $row, $fname );
2104                 }
2105         }
2106
2107         /**
2108          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2109          * statement.
2110          *
2111          * @param string $table Table name
2112          * @param array|string $rows Row(s) to insert
2113          * @param string $fname Caller function name
2114          *
2115          * @return ResultWrapper
2116          */
2117         protected function nativeReplace( $table, $rows, $fname ) {
2118                 $table = $this->tableName( $table );
2119
2120                 # Single row case
2121                 if ( !is_array( reset( $rows ) ) ) {
2122                         $rows = [ $rows ];
2123                 }
2124
2125                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2126                 $first = true;
2127
2128                 foreach ( $rows as $row ) {
2129                         if ( $first ) {
2130                                 $first = false;
2131                         } else {
2132                                 $sql .= ',';
2133                         }
2134
2135                         $sql .= '(' . $this->makeList( $row ) . ')';
2136                 }
2137
2138                 return $this->query( $sql, $fname );
2139         }
2140
2141         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2142                 $fname = __METHOD__
2143         ) {
2144                 if ( !count( $rows ) ) {
2145                         return true; // nothing to do
2146                 }
2147
2148                 if ( !is_array( reset( $rows ) ) ) {
2149                         $rows = [ $rows ];
2150                 }
2151
2152                 if ( count( $uniqueIndexes ) ) {
2153                         $clauses = []; // list WHERE clauses that each identify a single row
2154                         foreach ( $rows as $row ) {
2155                                 foreach ( $uniqueIndexes as $index ) {
2156                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2157                                         $rowKey = []; // unique key to this row
2158                                         foreach ( $index as $column ) {
2159                                                 $rowKey[$column] = $row[$column];
2160                                         }
2161                                         $clauses[] = $this->makeList( $rowKey, self::LIST_AND );
2162                                 }
2163                         }
2164                         $where = [ $this->makeList( $clauses, self::LIST_OR ) ];
2165                 } else {
2166                         $where = false;
2167                 }
2168
2169                 $useTrx = !$this->mTrxLevel;
2170                 if ( $useTrx ) {
2171                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2172                 }
2173                 try {
2174                         # Update any existing conflicting row(s)
2175                         if ( $where !== false ) {
2176                                 $ok = $this->update( $table, $set, $where, $fname );
2177                         } else {
2178                                 $ok = true;
2179                         }
2180                         # Now insert any non-conflicting row(s)
2181                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2182                 } catch ( Exception $e ) {
2183                         if ( $useTrx ) {
2184                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2185                         }
2186                         throw $e;
2187                 }
2188                 if ( $useTrx ) {
2189                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2190                 }
2191
2192                 return $ok;
2193         }
2194
2195         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2196                 $fname = __METHOD__
2197         ) {
2198                 if ( !$conds ) {
2199                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
2200                 }
2201
2202                 $delTable = $this->tableName( $delTable );
2203                 $joinTable = $this->tableName( $joinTable );
2204                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2205                 if ( $conds != '*' ) {
2206                         $sql .= 'WHERE ' . $this->makeList( $conds, self::LIST_AND );
2207                 }
2208                 $sql .= ')';
2209
2210                 $this->query( $sql, $fname );
2211         }
2212
2213         /**
2214          * Returns the size of a text field, or -1 for "unlimited"
2215          *
2216          * @param string $table
2217          * @param string $field
2218          * @return int
2219          */
2220         public function textFieldSize( $table, $field ) {
2221                 $table = $this->tableName( $table );
2222                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2223                 $res = $this->query( $sql, __METHOD__ );
2224                 $row = $this->fetchObject( $res );
2225
2226                 $m = [];
2227
2228                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2229                         $size = $m[1];
2230                 } else {
2231                         $size = -1;
2232                 }
2233
2234                 return $size;
2235         }
2236
2237         public function delete( $table, $conds, $fname = __METHOD__ ) {
2238                 if ( !$conds ) {
2239                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with no conditions' );
2240                 }
2241
2242                 $table = $this->tableName( $table );
2243                 $sql = "DELETE FROM $table";
2244
2245                 if ( $conds != '*' ) {
2246                         if ( is_array( $conds ) ) {
2247                                 $conds = $this->makeList( $conds, self::LIST_AND );
2248                         }
2249                         $sql .= ' WHERE ' . $conds;
2250                 }
2251
2252                 return $this->query( $sql, $fname );
2253         }
2254
2255         public function insertSelect(
2256                 $destTable, $srcTable, $varMap, $conds,
2257                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2258         ) {
2259                 if ( $this->cliMode ) {
2260                         // For massive migrations with downtime, we don't want to select everything
2261                         // into memory and OOM, so do all this native on the server side if possible.
2262                         return $this->nativeInsertSelect(
2263                                 $destTable,
2264                                 $srcTable,
2265                                 $varMap,
2266                                 $conds,
2267                                 $fname,
2268                                 $insertOptions,
2269                                 $selectOptions
2270                         );
2271                 }
2272
2273                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2274                 // on only the master (without needing row-based-replication). It also makes it easy to
2275                 // know how big the INSERT is going to be.
2276                 $fields = [];
2277                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2278                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2279                 }
2280                 $selectOptions[] = 'FOR UPDATE';
2281                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2282                 if ( !$res ) {
2283                         return false;
2284                 }
2285
2286                 $rows = [];
2287                 foreach ( $res as $row ) {
2288                         $rows[] = (array)$row;
2289                 }
2290
2291                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2292         }
2293
2294         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2295                 $fname = __METHOD__,
2296                 $insertOptions = [], $selectOptions = []
2297         ) {
2298                 $destTable = $this->tableName( $destTable );
2299
2300                 if ( !is_array( $insertOptions ) ) {
2301                         $insertOptions = [ $insertOptions ];
2302                 }
2303
2304                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2305
2306                 if ( !is_array( $selectOptions ) ) {
2307                         $selectOptions = [ $selectOptions ];
2308                 }
2309
2310                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2311                         $selectOptions );
2312
2313                 if ( is_array( $srcTable ) ) {
2314                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2315                 } else {
2316                         $srcTable = $this->tableName( $srcTable );
2317                 }
2318
2319                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2320                         " SELECT $startOpts " . implode( ',', $varMap ) .
2321                         " FROM $srcTable $useIndex $ignoreIndex ";
2322
2323                 if ( $conds != '*' ) {
2324                         if ( is_array( $conds ) ) {
2325                                 $conds = $this->makeList( $conds, self::LIST_AND );
2326                         }
2327                         $sql .= " WHERE $conds";
2328                 }
2329
2330                 $sql .= " $tailOpts";
2331
2332                 return $this->query( $sql, $fname );
2333         }
2334
2335         /**
2336          * Construct a LIMIT query with optional offset. This is used for query
2337          * pages. The SQL should be adjusted so that only the first $limit rows
2338          * are returned. If $offset is provided as well, then the first $offset
2339          * rows should be discarded, and the next $limit rows should be returned.
2340          * If the result of the query is not ordered, then the rows to be returned
2341          * are theoretically arbitrary.
2342          *
2343          * $sql is expected to be a SELECT, if that makes a difference.
2344          *
2345          * The version provided by default works in MySQL and SQLite. It will very
2346          * likely need to be overridden for most other DBMSes.
2347          *
2348          * @param string $sql SQL query we will append the limit too
2349          * @param int $limit The SQL limit
2350          * @param int|bool $offset The SQL offset (default false)
2351          * @throws DBUnexpectedError
2352          * @return string
2353          */
2354         public function limitResult( $sql, $limit, $offset = false ) {
2355                 if ( !is_numeric( $limit ) ) {
2356                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2357                 }
2358
2359                 return "$sql LIMIT "
2360                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2361                 . "{$limit} ";
2362         }
2363
2364         public function unionSupportsOrderAndLimit() {
2365                 return true; // True for almost every DB supported
2366         }
2367
2368         public function unionQueries( $sqls, $all ) {
2369                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2370
2371                 return '(' . implode( $glue, $sqls ) . ')';
2372         }
2373
2374         public function conditional( $cond, $trueVal, $falseVal ) {
2375                 if ( is_array( $cond ) ) {
2376                         $cond = $this->makeList( $cond, self::LIST_AND );
2377                 }
2378
2379                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2380         }
2381
2382         public function strreplace( $orig, $old, $new ) {
2383                 return "REPLACE({$orig}, {$old}, {$new})";
2384         }
2385
2386         public function getServerUptime() {
2387                 return 0;
2388         }
2389
2390         public function wasDeadlock() {
2391                 return false;
2392         }
2393
2394         public function wasLockTimeout() {
2395                 return false;
2396         }
2397
2398         public function wasErrorReissuable() {
2399                 return false;
2400         }
2401
2402         public function wasReadOnlyError() {
2403                 return false;
2404         }
2405
2406         /**
2407          * Determines if the given query error was a connection drop
2408          * STUB
2409          *
2410          * @param integer|string $errno
2411          * @return bool
2412          */
2413         public function wasConnectionError( $errno ) {
2414                 return false;
2415         }
2416
2417         /**
2418          * Perform a deadlock-prone transaction.
2419          *
2420          * This function invokes a callback function to perform a set of write
2421          * queries. If a deadlock occurs during the processing, the transaction
2422          * will be rolled back and the callback function will be called again.
2423          *
2424          * Avoid using this method outside of Job or Maintenance classes.
2425          *
2426          * Usage:
2427          *   $dbw->deadlockLoop( callback, ... );
2428          *
2429          * Extra arguments are passed through to the specified callback function.
2430          * This method requires that no transactions are already active to avoid
2431          * causing premature commits or exceptions.
2432          *
2433          * Returns whatever the callback function returned on its successful,
2434          * iteration, or false on error, for example if the retry limit was
2435          * reached.
2436          *
2437          * @return mixed
2438          * @throws DBUnexpectedError
2439          * @throws Exception
2440          */
2441         public function deadlockLoop() {
2442                 $args = func_get_args();
2443                 $function = array_shift( $args );
2444                 $tries = self::DEADLOCK_TRIES;
2445
2446                 $this->begin( __METHOD__ );
2447
2448                 $retVal = null;
2449                 /** @var Exception $e */
2450                 $e = null;
2451                 do {
2452                         try {
2453                                 $retVal = call_user_func_array( $function, $args );
2454                                 break;
2455                         } catch ( DBQueryError $e ) {
2456                                 if ( $this->wasDeadlock() ) {
2457                                         // Retry after a randomized delay
2458                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2459                                 } else {
2460                                         // Throw the error back up
2461                                         throw $e;
2462                                 }
2463                         }
2464                 } while ( --$tries > 0 );
2465
2466                 if ( $tries <= 0 ) {
2467                         // Too many deadlocks; give up
2468                         $this->rollback( __METHOD__ );
2469                         throw $e;
2470                 } else {
2471                         $this->commit( __METHOD__ );
2472
2473                         return $retVal;
2474                 }
2475         }
2476
2477         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2478                 # Real waits are implemented in the subclass.
2479                 return 0;
2480         }
2481
2482         public function getSlavePos() {
2483                 # Stub
2484                 return false;
2485         }
2486
2487         public function getMasterPos() {
2488                 # Stub
2489                 return false;
2490         }
2491
2492         public function serverIsReadOnly() {
2493                 return false;
2494         }
2495
2496         final public function onTransactionResolution( callable $callback, $fname = __METHOD__ ) {
2497                 if ( !$this->mTrxLevel ) {
2498                         throw new DBUnexpectedError( $this, "No transaction is active." );
2499                 }
2500                 $this->mTrxEndCallbacks[] = [ $callback, $fname ];
2501         }
2502
2503         final public function onTransactionIdle( callable $callback, $fname = __METHOD__ ) {
2504                 $this->mTrxIdleCallbacks[] = [ $callback, $fname ];
2505                 if ( !$this->mTrxLevel ) {
2506                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2507                 }
2508         }
2509
2510         final public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ ) {
2511                 if ( $this->mTrxLevel ) {
2512                         $this->mTrxPreCommitCallbacks[] = [ $callback, $fname ];
2513                 } else {
2514                         // If no transaction is active, then make one for this callback
2515                         $this->startAtomic( __METHOD__ );
2516                         try {
2517                                 call_user_func( $callback );
2518                                 $this->endAtomic( __METHOD__ );
2519                         } catch ( Exception $e ) {
2520                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2521                                 throw $e;
2522                         }
2523                 }
2524         }
2525
2526         final public function setTransactionListener( $name, callable $callback = null ) {
2527                 if ( $callback ) {
2528                         $this->mTrxRecurringCallbacks[$name] = $callback;
2529                 } else {
2530                         unset( $this->mTrxRecurringCallbacks[$name] );
2531                 }
2532         }
2533
2534         /**
2535          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2536          *
2537          * This method should not be used outside of Database/LoadBalancer
2538          *
2539          * @param bool $suppress
2540          * @since 1.28
2541          */
2542         final public function setTrxEndCallbackSuppression( $suppress ) {
2543                 $this->mTrxEndCallbacksSuppressed = $suppress;
2544         }
2545
2546         /**
2547          * Actually run and consume any "on transaction idle/resolution" callbacks.
2548          *
2549          * This method should not be used outside of Database/LoadBalancer
2550          *
2551          * @param integer $trigger IDatabase::TRIGGER_* constant
2552          * @since 1.20
2553          * @throws Exception
2554          */
2555         public function runOnTransactionIdleCallbacks( $trigger ) {
2556                 if ( $this->mTrxEndCallbacksSuppressed ) {
2557                         return;
2558                 }
2559
2560                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2561                 /** @var Exception $e */
2562                 $e = null; // first exception
2563                 do { // callbacks may add callbacks :)
2564                         $callbacks = array_merge(
2565                                 $this->mTrxIdleCallbacks,
2566                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2567                         );
2568                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2569                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2570                         foreach ( $callbacks as $callback ) {
2571                                 try {
2572                                         list( $phpCallback ) = $callback;
2573                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2574                                         call_user_func_array( $phpCallback, [ $trigger ] );
2575                                         if ( $autoTrx ) {
2576                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2577                                         } else {
2578                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2579                                         }
2580                                 } catch ( Exception $ex ) {
2581                                         call_user_func( $this->errorLogger, $ex );
2582                                         $e = $e ?: $ex;
2583                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2584                                         // their transactions are ended so other callbacks don't fail
2585                                         if ( $this->trxLevel() ) {
2586                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2587                                         }
2588                                 }
2589                         }
2590                 } while ( count( $this->mTrxIdleCallbacks ) );
2591
2592                 if ( $e instanceof Exception ) {
2593                         throw $e; // re-throw any first exception
2594                 }
2595         }
2596
2597         /**
2598          * Actually run and consume any "on transaction pre-commit" callbacks.
2599          *
2600          * This method should not be used outside of Database/LoadBalancer
2601          *
2602          * @since 1.22
2603          * @throws Exception
2604          */
2605         public function runOnTransactionPreCommitCallbacks() {
2606                 $e = null; // first exception
2607                 do { // callbacks may add callbacks :)
2608                         $callbacks = $this->mTrxPreCommitCallbacks;
2609                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2610                         foreach ( $callbacks as $callback ) {
2611                                 try {
2612                                         list( $phpCallback ) = $callback;
2613                                         call_user_func( $phpCallback );
2614                                 } catch ( Exception $ex ) {
2615                                         call_user_func( $this->errorLogger, $ex );
2616                                         $e = $e ?: $ex;
2617                                 }
2618                         }
2619                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2620
2621                 if ( $e instanceof Exception ) {
2622                         throw $e; // re-throw any first exception
2623                 }
2624         }
2625
2626         /**
2627          * Actually run any "transaction listener" callbacks.
2628          *
2629          * This method should not be used outside of Database/LoadBalancer
2630          *
2631          * @param integer $trigger IDatabase::TRIGGER_* constant
2632          * @throws Exception
2633          * @since 1.20
2634          */
2635         public function runTransactionListenerCallbacks( $trigger ) {
2636                 if ( $this->mTrxEndCallbacksSuppressed ) {
2637                         return;
2638                 }
2639
2640                 /** @var Exception $e */
2641                 $e = null; // first exception
2642
2643                 foreach ( $this->mTrxRecurringCallbacks as $phpCallback ) {
2644                         try {
2645                                 $phpCallback( $trigger, $this );
2646                         } catch ( Exception $ex ) {
2647                                 call_user_func( $this->errorLogger, $ex );
2648                                 $e = $e ?: $ex;
2649                         }
2650                 }
2651
2652                 if ( $e instanceof Exception ) {
2653                         throw $e; // re-throw any first exception
2654                 }
2655         }
2656
2657         final public function startAtomic( $fname = __METHOD__ ) {
2658                 if ( !$this->mTrxLevel ) {
2659                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2660                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2661                         // in all changes being in one transaction to keep requests transactional.
2662                         if ( !$this->getFlag( DBO_TRX ) ) {
2663                                 $this->mTrxAutomaticAtomic = true;
2664                         }
2665                 }
2666
2667                 $this->mTrxAtomicLevels[] = $fname;
2668         }
2669
2670         final public function endAtomic( $fname = __METHOD__ ) {
2671                 if ( !$this->mTrxLevel ) {
2672                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2673                 }
2674                 if ( !$this->mTrxAtomicLevels ||
2675                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2676                 ) {
2677                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2678                 }
2679
2680                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2681                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2682                 }
2683         }
2684
2685         final public function doAtomicSection( $fname, callable $callback ) {
2686                 $this->startAtomic( $fname );
2687                 try {
2688                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2689                 } catch ( Exception $e ) {
2690                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2691                         throw $e;
2692                 }
2693                 $this->endAtomic( $fname );
2694
2695                 return $res;
2696         }
2697
2698         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2699                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2700                 if ( $this->mTrxLevel ) {
2701                         if ( $this->mTrxAtomicLevels ) {
2702                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2703                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2704                                 throw new DBUnexpectedError( $this, $msg );
2705                         } elseif ( !$this->mTrxAutomatic ) {
2706                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2707                                 throw new DBUnexpectedError( $this, $msg );
2708                         } else {
2709                                 // @TODO: make this an exception at some point
2710                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2711                                 $this->queryLogger->error( $msg );
2712                                 return; // join the main transaction set
2713                         }
2714                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2715                         // @TODO: make this an exception at some point
2716                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2717                         $this->queryLogger->error( $msg );
2718                         return; // let any writes be in the main transaction
2719                 }
2720
2721                 // Avoid fatals if close() was called
2722                 $this->assertOpen();
2723
2724                 $this->doBegin( $fname );
2725                 $this->mTrxTimestamp = microtime( true );
2726                 $this->mTrxFname = $fname;
2727                 $this->mTrxDoneWrites = false;
2728                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2729                 $this->mTrxAutomaticAtomic = false;
2730                 $this->mTrxAtomicLevels = [];
2731                 $this->mTrxShortId = sprintf( '%06x', mt_rand( 0, 0xffffff ) );
2732                 $this->mTrxWriteDuration = 0.0;
2733                 $this->mTrxWriteQueryCount = 0;
2734                 $this->mTrxWriteAdjDuration = 0.0;
2735                 $this->mTrxWriteAdjQueryCount = 0;
2736                 $this->mTrxWriteCallers = [];
2737                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2738                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2739                 // as lag itself just to be safe
2740                 $status = $this->getApproximateLagStatus();
2741                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2742         }
2743
2744         /**
2745          * Issues the BEGIN command to the database server.
2746          *
2747          * @see DatabaseBase::begin()
2748          * @param string $fname
2749          */
2750         protected function doBegin( $fname ) {
2751                 $this->query( 'BEGIN', $fname );
2752                 $this->mTrxLevel = 1;
2753         }
2754
2755         final public function commit( $fname = __METHOD__, $flush = '' ) {
2756                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2757                         // There are still atomic sections open. This cannot be ignored
2758                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2759                         throw new DBUnexpectedError(
2760                                 $this,
2761                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2762                         );
2763                 }
2764
2765                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2766                         if ( !$this->mTrxLevel ) {
2767                                 return; // nothing to do
2768                         } elseif ( !$this->mTrxAutomatic ) {
2769                                 throw new DBUnexpectedError(
2770                                         $this,
2771                                         "$fname: Flushing an explicit transaction, getting out of sync."
2772                                 );
2773                         }
2774                 } else {
2775                         if ( !$this->mTrxLevel ) {
2776                                 $this->queryLogger->error( "$fname: No transaction to commit, something got out of sync." );
2777                                 return; // nothing to do
2778                         } elseif ( $this->mTrxAutomatic ) {
2779                                 // @TODO: make this an exception at some point
2780                                 $msg = "$fname: Explicit commit of implicit transaction.";
2781                                 $this->queryLogger->error( $msg );
2782                                 return; // wait for the main transaction set commit round
2783                         }
2784                 }
2785
2786                 // Avoid fatals if close() was called
2787                 $this->assertOpen();
2788
2789                 $this->runOnTransactionPreCommitCallbacks();
2790                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
2791                 $this->doCommit( $fname );
2792                 if ( $this->mTrxDoneWrites ) {
2793                         $this->mDoneWrites = microtime( true );
2794                         $this->trxProfiler->transactionWritingOut(
2795                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2796                 }
2797
2798                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2799                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
2800         }
2801
2802         /**
2803          * Issues the COMMIT command to the database server.
2804          *
2805          * @see DatabaseBase::commit()
2806          * @param string $fname
2807          */
2808         protected function doCommit( $fname ) {
2809                 if ( $this->mTrxLevel ) {
2810                         $this->query( 'COMMIT', $fname );
2811                         $this->mTrxLevel = 0;
2812                 }
2813         }
2814
2815         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2816                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2817                         if ( !$this->mTrxLevel ) {
2818                                 return; // nothing to do
2819                         }
2820                 } else {
2821                         if ( !$this->mTrxLevel ) {
2822                                 $this->queryLogger->error(
2823                                         "$fname: No transaction to rollback, something got out of sync." );
2824                                 return; // nothing to do
2825                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2826                                 throw new DBUnexpectedError(
2827                                         $this,
2828                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2829                                 );
2830                         }
2831                 }
2832
2833                 // Avoid fatals if close() was called
2834                 $this->assertOpen();
2835
2836                 $this->doRollback( $fname );
2837                 $this->mTrxAtomicLevels = [];
2838                 if ( $this->mTrxDoneWrites ) {
2839                         $this->trxProfiler->transactionWritingOut(
2840                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2841                 }
2842
2843                 $this->mTrxIdleCallbacks = []; // clear
2844                 $this->mTrxPreCommitCallbacks = []; // clear
2845                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2846                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
2847         }
2848
2849         /**
2850          * Issues the ROLLBACK command to the database server.
2851          *
2852          * @see DatabaseBase::rollback()
2853          * @param string $fname
2854          */
2855         protected function doRollback( $fname ) {
2856                 if ( $this->mTrxLevel ) {
2857                         # Disconnects cause rollback anyway, so ignore those errors
2858                         $ignoreErrors = true;
2859                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2860                         $this->mTrxLevel = 0;
2861                 }
2862         }
2863
2864         public function flushSnapshot( $fname = __METHOD__ ) {
2865                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
2866                         // This only flushes transactions to clear snapshots, not to write data
2867                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
2868                         throw new DBUnexpectedError(
2869                                 $this,
2870                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
2871                         );
2872                 }
2873
2874                 $this->commit( $fname, self::FLUSHING_INTERNAL );
2875         }
2876
2877         public function explicitTrxActive() {
2878                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2879         }
2880
2881         /**
2882          * Creates a new table with structure copied from existing table
2883          * Note that unlike most database abstraction functions, this function does not
2884          * automatically append database prefix, because it works at a lower
2885          * abstraction level.
2886          * The table names passed to this function shall not be quoted (this
2887          * function calls addIdentifierQuotes when needed).
2888          *
2889          * @param string $oldName Name of table whose structure should be copied
2890          * @param string $newName Name of table to be created
2891          * @param bool $temporary Whether the new table should be temporary
2892          * @param string $fname Calling function name
2893          * @throws RuntimeException
2894          * @return bool True if operation was successful
2895          */
2896         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2897                 $fname = __METHOD__
2898         ) {
2899                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2900         }
2901
2902         function listTables( $prefix = null, $fname = __METHOD__ ) {
2903                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2904         }
2905
2906         /**
2907          * Reset the views process cache set by listViews()
2908          * @since 1.22
2909          */
2910         final public function clearViewsCache() {
2911                 $this->allViews = null;
2912         }
2913
2914         /**
2915          * Lists all the VIEWs in the database
2916          *
2917          * For caching purposes the list of all views should be stored in
2918          * $this->allViews. The process cache can be cleared with clearViewsCache()
2919          *
2920          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2921          * @param string $fname Name of calling function
2922          * @throws RuntimeException
2923          * @return array
2924          * @since 1.22
2925          */
2926         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2927                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2928         }
2929
2930         /**
2931          * Differentiates between a TABLE and a VIEW
2932          *
2933          * @param string $name Name of the database-structure to test.
2934          * @throws RuntimeException
2935          * @return bool
2936          * @since 1.22
2937          */
2938         public function isView( $name ) {
2939                 throw new RuntimeException( __METHOD__ . ' is not implemented in descendant class' );
2940         }
2941
2942         public function timestamp( $ts = 0 ) {
2943                 $t = new ConvertableTimestamp( $ts );
2944                 // Let errors bubble up to avoid putting garbage in the DB
2945                 return $t->getTimestamp( TS_MW );
2946         }
2947
2948         public function timestampOrNull( $ts = null ) {
2949                 if ( is_null( $ts ) ) {
2950                         return null;
2951                 } else {
2952                         return $this->timestamp( $ts );
2953                 }
2954         }
2955
2956         /**
2957          * Take the result from a query, and wrap it in a ResultWrapper if
2958          * necessary. Boolean values are passed through as is, to indicate success
2959          * of write queries or failure.
2960          *
2961          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2962          * resource, and it was necessary to call this function to convert it to
2963          * a wrapper. Nowadays, raw database objects are never exposed to external
2964          * callers, so this is unnecessary in external code.
2965          *
2966          * @param bool|ResultWrapper|resource|object $result
2967          * @return bool|ResultWrapper
2968          */
2969         protected function resultObject( $result ) {
2970                 if ( !$result ) {
2971                         return false;
2972                 } elseif ( $result instanceof ResultWrapper ) {
2973                         return $result;
2974                 } elseif ( $result === true ) {
2975                         // Successful write query
2976                         return $result;
2977                 } else {
2978                         return new ResultWrapper( $this, $result );
2979                 }
2980         }
2981
2982         public function ping( &$rtt = null ) {
2983                 // Avoid hitting the server if it was hit recently
2984                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2985                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
2986                                 $rtt = $this->mRTTEstimate;
2987                                 return true; // don't care about $rtt
2988                         }
2989                 }
2990
2991                 // This will reconnect if possible or return false if not
2992                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
2993                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
2994                 $this->restoreFlags( self::RESTORE_PRIOR );
2995
2996                 if ( $ok ) {
2997                         $rtt = $this->mRTTEstimate;
2998                 }
2999
3000                 return $ok;
3001         }
3002
3003         /**
3004          * @return bool
3005          */
3006         protected function reconnect() {
3007                 $this->closeConnection();
3008                 $this->mOpened = false;
3009                 $this->mConn = false;
3010                 try {
3011                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3012                         $this->lastPing = microtime( true );
3013                         $ok = true;
3014                 } catch ( DBConnectionError $e ) {
3015                         $ok = false;
3016                 }
3017
3018                 return $ok;
3019         }
3020
3021         public function getSessionLagStatus() {
3022                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3023         }
3024
3025         /**
3026          * Get the replica DB lag when the current transaction started
3027          *
3028          * This is useful when transactions might use snapshot isolation
3029          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3030          * is this lag plus transaction duration. If they don't, it is still
3031          * safe to be pessimistic. This returns null if there is no transaction.
3032          *
3033          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3034          * @since 1.27
3035          */
3036         public function getTransactionLagStatus() {
3037                 return $this->mTrxLevel
3038                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3039                         : null;
3040         }
3041
3042         /**
3043          * Get a replica DB lag estimate for this server
3044          *
3045          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3046          * @since 1.27
3047          */
3048         public function getApproximateLagStatus() {
3049                 return [
3050                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3051                         'since' => microtime( true )
3052                 ];
3053         }
3054
3055         /**
3056          * Merge the result of getSessionLagStatus() for several DBs
3057          * using the most pessimistic values to estimate the lag of
3058          * any data derived from them in combination
3059          *
3060          * This is information is useful for caching modules
3061          *
3062          * @see WANObjectCache::set()
3063          * @see WANObjectCache::getWithSetCallback()
3064          *
3065          * @param IDatabase $db1
3066          * @param IDatabase ...
3067          * @return array Map of values:
3068          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3069          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3070          *   - pending: whether any of the DBs have uncommitted changes
3071          * @since 1.27
3072          */
3073         public static function getCacheSetOptions( IDatabase $db1 ) {
3074                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3075                 foreach ( func_get_args() as $db ) {
3076                         /** @var IDatabase $db */
3077                         $status = $db->getSessionLagStatus();
3078                         if ( $status['lag'] === false ) {
3079                                 $res['lag'] = false;
3080                         } elseif ( $res['lag'] !== false ) {
3081                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3082                         }
3083                         $res['since'] = min( $res['since'], $status['since'] );
3084                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3085                 }
3086
3087                 return $res;
3088         }
3089
3090         public function getLag() {
3091                 return 0;
3092         }
3093
3094         function maxListLen() {
3095                 return 0;
3096         }
3097
3098         public function encodeBlob( $b ) {
3099                 return $b;
3100         }
3101
3102         public function decodeBlob( $b ) {
3103                 if ( $b instanceof Blob ) {
3104                         $b = $b->fetch();
3105                 }
3106                 return $b;
3107         }
3108
3109         public function setSessionOptions( array $options ) {
3110         }
3111
3112         /**
3113          * Read and execute SQL commands from a file.
3114          *
3115          * Returns true on success, error string or exception on failure (depending
3116          * on object's error ignore settings).
3117          *
3118          * @param string $filename File name to open
3119          * @param bool|callable $lineCallback Optional function called before reading each line
3120          * @param bool|callable $resultCallback Optional function called for each MySQL result
3121          * @param bool|string $fname Calling function name or false if name should be
3122          *   generated dynamically using $filename
3123          * @param bool|callable $inputCallback Optional function called for each
3124          *   complete line sent
3125          * @return bool|string
3126          * @throws Exception
3127          */
3128         public function sourceFile(
3129                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3130         ) {
3131                 MediaWiki\suppressWarnings();
3132                 $fp = fopen( $filename, 'r' );
3133                 MediaWiki\restoreWarnings();
3134
3135                 if ( false === $fp ) {
3136                         throw new RuntimeException( "Could not open \"{$filename}\".\n" );
3137                 }
3138
3139                 if ( !$fname ) {
3140                         $fname = __METHOD__ . "( $filename )";
3141                 }
3142
3143                 try {
3144                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3145                 } catch ( Exception $e ) {
3146                         fclose( $fp );
3147                         throw $e;
3148                 }
3149
3150                 fclose( $fp );
3151
3152                 return $error;
3153         }
3154
3155         public function setSchemaVars( $vars ) {
3156                 $this->mSchemaVars = $vars;
3157         }
3158
3159         /**
3160          * Read and execute commands from an open file handle.
3161          *
3162          * Returns true on success, error string or exception on failure (depending
3163          * on object's error ignore settings).
3164          *
3165          * @param resource $fp File handle
3166          * @param bool|callable $lineCallback Optional function called before reading each query
3167          * @param bool|callable $resultCallback Optional function called for each MySQL result
3168          * @param string $fname Calling function name
3169          * @param bool|callable $inputCallback Optional function called for each complete query sent
3170          * @return bool|string
3171          */
3172         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3173                 $fname = __METHOD__, $inputCallback = false
3174         ) {
3175                 $cmd = '';
3176
3177                 while ( !feof( $fp ) ) {
3178                         if ( $lineCallback ) {
3179                                 call_user_func( $lineCallback );
3180                         }
3181
3182                         $line = trim( fgets( $fp ) );
3183
3184                         if ( $line == '' ) {
3185                                 continue;
3186                         }
3187
3188                         if ( '-' == $line[0] && '-' == $line[1] ) {
3189                                 continue;
3190                         }
3191
3192                         if ( $cmd != '' ) {
3193                                 $cmd .= ' ';
3194                         }
3195
3196                         $done = $this->streamStatementEnd( $cmd, $line );
3197
3198                         $cmd .= "$line\n";
3199
3200                         if ( $done || feof( $fp ) ) {
3201                                 $cmd = $this->replaceVars( $cmd );
3202
3203                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3204                                         $res = $this->query( $cmd, $fname );
3205
3206                                         if ( $resultCallback ) {
3207                                                 call_user_func( $resultCallback, $res, $this );
3208                                         }
3209
3210                                         if ( false === $res ) {
3211                                                 $err = $this->lastError();
3212
3213                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3214                                         }
3215                                 }
3216                                 $cmd = '';
3217                         }
3218                 }
3219
3220                 return true;
3221         }
3222
3223         /**
3224          * Called by sourceStream() to check if we've reached a statement end
3225          *
3226          * @param string $sql SQL assembled so far
3227          * @param string $newLine New line about to be added to $sql
3228          * @return bool Whether $newLine contains end of the statement
3229          */
3230         public function streamStatementEnd( &$sql, &$newLine ) {
3231                 if ( $this->delimiter ) {
3232                         $prev = $newLine;
3233                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3234                         if ( $newLine != $prev ) {
3235                                 return true;
3236                         }
3237                 }
3238
3239                 return false;
3240         }
3241
3242         /**
3243          * Database independent variable replacement. Replaces a set of variables
3244          * in an SQL statement with their contents as given by $this->getSchemaVars().
3245          *
3246          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3247          *
3248          * - '{$var}' should be used for text and is passed through the database's
3249          *   addQuotes method.
3250          * - `{$var}` should be used for identifiers (e.g. table and database names).
3251          *   It is passed through the database's addIdentifierQuotes method which
3252          *   can be overridden if the database uses something other than backticks.
3253          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3254          *   database's tableName method.
3255          * - / *i* / passes the name that follows through the database's indexName method.
3256          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3257          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3258          *
3259          * @param string $ins SQL statement to replace variables in
3260          * @return string The new SQL statement with variables replaced
3261          */
3262         protected function replaceVars( $ins ) {
3263                 $vars = $this->getSchemaVars();
3264                 return preg_replace_callback(
3265                         '!
3266                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3267                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3268                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3269                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3270                         !x',
3271                         function ( $m ) use ( $vars ) {
3272                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3273                                 // check for both nonexistent keys *and* the empty string.
3274                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3275                                         if ( $m[1] === 'i' ) {
3276                                                 return $this->indexName( $m[2] );
3277                                         } else {
3278                                                 return $this->tableName( $m[2] );
3279                                         }
3280                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3281                                         return $this->addQuotes( $vars[$m[3]] );
3282                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3283                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3284                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3285                                         return $vars[$m[5]];
3286                                 } else {
3287                                         return $m[0];
3288                                 }
3289                         },
3290                         $ins
3291                 );
3292         }
3293
3294         /**
3295          * Get schema variables. If none have been set via setSchemaVars(), then
3296          * use some defaults from the current object.
3297          *
3298          * @return array
3299          */
3300         protected function getSchemaVars() {
3301                 if ( $this->mSchemaVars ) {
3302                         return $this->mSchemaVars;
3303                 } else {
3304                         return $this->getDefaultSchemaVars();
3305                 }
3306         }
3307
3308         /**
3309          * Get schema variables to use if none have been set via setSchemaVars().
3310          *
3311          * Override this in derived classes to provide variables for tables.sql
3312          * and SQL patch files.
3313          *
3314          * @return array
3315          */
3316         protected function getDefaultSchemaVars() {
3317                 return [];
3318         }
3319
3320         public function lockIsFree( $lockName, $method ) {
3321                 return true;
3322         }
3323
3324         public function lock( $lockName, $method, $timeout = 5 ) {
3325                 $this->mNamedLocksHeld[$lockName] = 1;
3326
3327                 return true;
3328         }
3329
3330         public function unlock( $lockName, $method ) {
3331                 unset( $this->mNamedLocksHeld[$lockName] );
3332
3333                 return true;
3334         }
3335
3336         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3337                 if ( $this->writesOrCallbacksPending() ) {
3338                         // This only flushes transactions to clear snapshots, not to write data
3339                         $fnames = implode( ', ', $this->pendingWriteAndCallbackCallers() );
3340                         throw new DBUnexpectedError(
3341                                 $this,
3342                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending ($fnames)."
3343                         );
3344                 }
3345
3346                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3347                         return null;
3348                 }
3349
3350                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3351                         if ( $this->trxLevel() ) {
3352                                 // There is a good chance an exception was thrown, causing any early return
3353                                 // from the caller. Let any error handler get a chance to issue rollback().
3354                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3355                                 $this->onTransactionResolution(
3356                                         function () use ( $lockKey, $fname ) {
3357                                                 $this->unlock( $lockKey, $fname );
3358                                         },
3359                                         $fname
3360                                 );
3361                         } else {
3362                                 $this->unlock( $lockKey, $fname );
3363                         }
3364                 } );
3365
3366                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3367
3368                 return $unlocker;
3369         }
3370
3371         public function namedLocksEnqueue() {
3372                 return false;
3373         }
3374
3375         /**
3376          * Lock specific tables
3377          *
3378          * @param array $read Array of tables to lock for read access
3379          * @param array $write Array of tables to lock for write access
3380          * @param string $method Name of caller
3381          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3382          * @return bool
3383          */
3384         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3385                 return true;
3386         }
3387
3388         /**
3389          * Unlock specific tables
3390          *
3391          * @param string $method The caller
3392          * @return bool
3393          */
3394         public function unlockTables( $method ) {
3395                 return true;
3396         }
3397
3398         /**
3399          * Delete a table
3400          * @param string $tableName
3401          * @param string $fName
3402          * @return bool|ResultWrapper
3403          * @since 1.18
3404          */
3405         public function dropTable( $tableName, $fName = __METHOD__ ) {
3406                 if ( !$this->tableExists( $tableName, $fName ) ) {
3407                         return false;
3408                 }
3409                 $sql = "DROP TABLE " . $this->tableName( $tableName ) . " CASCADE";
3410
3411                 return $this->query( $sql, $fName );
3412         }
3413
3414         public function getInfinity() {
3415                 return 'infinity';
3416         }
3417
3418         public function encodeExpiry( $expiry ) {
3419                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3420                         ? $this->getInfinity()
3421                         : $this->timestamp( $expiry );
3422         }
3423
3424         public function decodeExpiry( $expiry, $format = TS_MW ) {
3425                 if ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() ) {
3426                         return 'infinity';
3427                 }
3428
3429                 try {
3430                         $t = new ConvertableTimestamp( $expiry );
3431
3432                         return $t->getTimestamp( $format );
3433                 } catch ( TimestampException $e ) {
3434                         return false;
3435                 }
3436         }
3437
3438         public function setBigSelects( $value = true ) {
3439                 // no-op
3440         }
3441
3442         public function isReadOnly() {
3443                 return ( $this->getReadOnlyReason() !== false );
3444         }
3445
3446         /**
3447          * @return string|bool Reason this DB is read-only or false if it is not
3448          */
3449         protected function getReadOnlyReason() {
3450                 $reason = $this->getLBInfo( 'readOnlyReason' );
3451
3452                 return is_string( $reason ) ? $reason : false;
3453         }
3454
3455         public function setTableAliases( array $aliases ) {
3456                 $this->tableAliases = $aliases;
3457         }
3458
3459         /**
3460          * @since 1.19
3461          * @return string
3462          */
3463         public function __toString() {
3464                 return (string)$this->mConn;
3465         }
3466
3467         /**
3468          * Called by serialize. Throw an exception when DB connection is serialized.
3469          * This causes problems on some database engines because the connection is
3470          * not restored on unserialize.
3471          */
3472         public function __sleep() {
3473                 throw new RuntimeException( 'Database serialization may cause problems, since ' .
3474                         'the connection is not restored on wakeup.' );
3475         }
3476
3477         /**
3478          * Run a few simple sanity checks
3479          */
3480         public function __destruct() {
3481                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3482                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3483                 }
3484
3485                 $danglingWriters = $this->pendingWriteAndCallbackCallers();
3486                 if ( $danglingWriters ) {
3487                         $fnames = implode( ', ', $danglingWriters );
3488                         trigger_error( "DB transaction writes or callbacks still pending ($fnames)." );
3489                 }
3490         }
3491 }