includes/db/Database.php

   1 <?php
   2
   3 /**
   4  * @defgroup Database Database
   5  *
   6  * This file deals with database interface functions
   7  * and query specifics/optimisations.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  * @ingroup Database
  26  */
  27
  28 /**
  29  * Database abstraction object
  30  * @ingroup Database
  31  */
  32 abstract class DatabaseBase implements IDatabase {
  33         /** Number of times to re-try an operation in case of deadlock */
  34         const DEADLOCK_TRIES = 4;
  35         /** Minimum time to wait before retry, in microseconds */
  36         const DEADLOCK_DELAY_MIN = 500000;
  37         /** Maximum time to wait before retry */
  38         const DEADLOCK_DELAY_MAX = 1500000;
  39
  40         /** How long before it is worth doing a dummy query to test the connection */
  41         const PING_TTL = 1.0;
  42
  43         /** @var string SQL query */
  44         protected $mLastQuery = '';
  45         /** @var bool */
  46         protected $mDoneWrites = false;
  47         /** @var string|bool */
  48         protected $mPHPError = false;
  49         /** @var string */
  50         protected $mServer;
  51         /** @var string */
  52         protected $mUser;
  53         /** @var string */
  54         protected $mPassword;
  55         /** @var string */
  56         protected $mDBname;
  57
  58         /** @var BagOStuff APC cache */
  59         protected $srvCache;
  60
  61         /** @var resource Database connection */
  62         protected $mConn = null;
  63         /** @var bool */
  64         protected $mOpened = false;
  65
  66         /** @var array[] List of (callable, method name) */
  67         protected $mTrxIdleCallbacks = [];
  68         /** @var array[] List of (callable, method name) */
  69         protected $mTrxPreCommitCallbacks = [];
  70         /** @var array[] List of (callable, method name) */
  71         protected $mTrxEndCallbacks = [];
  72         /** @var bool Whether to suppress triggering of post-commit callbacks */
  73         protected $suppressPostCommitCallbacks = false;
  74
  75         /** @var string */
  76         protected $mTablePrefix;
  77         /** @var string */
  78         protected $mSchema;
  79         /** @var integer */
  80         protected $mFlags;
  81         /** @var bool */
  82         protected $mForeign;
  83         /** @var array */
  84         protected $mLBInfo = [];
  85         /** @var bool|null */
  86         protected $mDefaultBigSelects = null;
  87         /** @var array|bool */
  88         protected $mSchemaVars = false;
  89         /** @var array */
  90         protected $mSessionVars = [];
  91         /** @var array|null */
  92         protected $preparedArgs;
  93         /** @var string|bool|null Stashed value of html_errors INI setting */
  94         protected $htmlErrors;
  95         /** @var string */
  96         protected $delimiter = ';';
  97
  98         /**
  99          * Either 1 if a transaction is active or 0 otherwise.
 100          * The other Trx fields may not be meaningfull if this is 0.
 101          *
 102          * @var int
 103          */
 104         protected $mTrxLevel = 0;
 105
 106         /**
 107          * Either a short hexidecimal string if a transaction is active or ""
 108          *
 109          * @var string
 110          * @see DatabaseBase::mTrxLevel
 111          */
 112         protected $mTrxShortId = '';
 113
 114         /**
 115          * The UNIX time that the transaction started. Callers can assume that if
 116          * snapshot isolation is used, then the data is *at least* up to date to that
 117          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 118          *
 119          * @var float|null
 120          * @see DatabaseBase::mTrxLevel
 121          */
 122         private $mTrxTimestamp = null;
 123
 124         /** @var float Lag estimate at the time of BEGIN */
 125         private $mTrxSlaveLag = null;
 126
 127         /**
 128          * Remembers the function name given for starting the most recent transaction via begin().
 129          * Used to provide additional context for error reporting.
 130          *
 131          * @var string
 132          * @see DatabaseBase::mTrxLevel
 133          */
 134         private $mTrxFname = null;
 135
 136         /**
 137          * Record if possible write queries were done in the last transaction started
 138          *
 139          * @var bool
 140          * @see DatabaseBase::mTrxLevel
 141          */
 142         private $mTrxDoneWrites = false;
 143
 144         /**
 145          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 146          *
 147          * @var bool
 148          * @see DatabaseBase::mTrxLevel
 149          */
 150         private $mTrxAutomatic = false;
 151
 152         /**
 153          * Array of levels of atomicity within transactions
 154          *
 155          * @var array
 156          */
 157         private $mTrxAtomicLevels = [];
 158
 159         /**
 160          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 161          *
 162          * @var bool
 163          */
 164         private $mTrxAutomaticAtomic = false;
 165
 166         /**
 167          * Track the write query callers of the current transaction
 168          *
 169          * @var string[]
 170          */
 171         private $mTrxWriteCallers = [];
 172
 173         /**
 174          * Track the seconds spent in write queries for the current transaction
 175          *
 176          * @var float
 177          */
 178         private $mTrxWriteDuration = 0.0;
 179
 180         /** @var array Map of (name => 1) for locks obtained via lock() */
 181         private $mNamedLocksHeld = [];
 182
 183         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 184         private $lazyMasterHandle;
 185
 186         /**
 187          * @since 1.21
 188          * @var resource File handle for upgrade
 189          */
 190         protected $fileHandle = null;
 191
 192         /**
 193          * @since 1.22
 194          * @var string[] Process cache of VIEWs names in the database
 195          */
 196         protected $allViews = null;
 197
 198         /** @var float UNIX timestamp */
 199         protected $lastPing = 0.0;
 200
 201         /** @var TransactionProfiler */
 202         protected $trxProfiler;
 203
 204         public function getServerInfo() {
 205                 return $this->getServerVersion();
 206         }
 207
 208         /**
 209          * @return string Command delimiter used by this database engine
 210          */
 211         public function getDelimiter() {
 212                 return $this->delimiter;
 213         }
 214
 215         /**
 216          * Boolean, controls output of large amounts of debug information.
 217          * @param bool|null $debug
 218          *   - true to enable debugging
 219          *   - false to disable debugging
 220          *   - omitted or null to do nothing
 221          *
 222          * @return bool|null Previous value of the flag
 223          */
 224         public function debug( $debug = null ) {
 225                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 226         }
 227
 228         public function bufferResults( $buffer = null ) {
 229                 if ( is_null( $buffer ) ) {
 230                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 231                 } else {
 232                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 233                 }
 234         }
 235
 236         /**
 237          * Turns on (false) or off (true) the automatic generation and sending
 238          * of a "we're sorry, but there has been a database error" page on
 239          * database errors. Default is on (false). When turned off, the
 240          * code should use lastErrno() and lastError() to handle the
 241          * situation as appropriate.
 242          *
 243          * Do not use this function outside of the Database classes.
 244          *
 245          * @param null|bool $ignoreErrors
 246          * @return bool The previous value of the flag.
 247          */
 248         protected function ignoreErrors( $ignoreErrors = null ) {
 249                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 250         }
 251
 252         public function trxLevel() {
 253                 return $this->mTrxLevel;
 254         }
 255
 256         public function trxTimestamp() {
 257                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 258         }
 259
 260         public function tablePrefix( $prefix = null ) {
 261                 return wfSetVar( $this->mTablePrefix, $prefix );
 262         }
 263
 264         public function dbSchema( $schema = null ) {
 265                 return wfSetVar( $this->mSchema, $schema );
 266         }
 267
 268         /**
 269          * Set the filehandle to copy write statements to.
 270          *
 271          * @param resource $fh File handle
 272          */
 273         public function setFileHandle( $fh ) {
 274                 $this->fileHandle = $fh;
 275         }
 276
 277         public function getLBInfo( $name = null ) {
 278                 if ( is_null( $name ) ) {
 279                         return $this->mLBInfo;
 280                 } else {
 281                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 282                                 return $this->mLBInfo[$name];
 283                         } else {
 284                                 return null;
 285                         }
 286                 }
 287         }
 288
 289         public function setLBInfo( $name, $value = null ) {
 290                 if ( is_null( $value ) ) {
 291                         $this->mLBInfo = $name;
 292                 } else {
 293                         $this->mLBInfo[$name] = $value;
 294                 }
 295         }
 296
 297         /**
 298          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 299          *
 300          * @param IDatabase $conn
 301          * @since 1.27
 302          */
 303         public function setLazyMasterHandle( IDatabase $conn ) {
 304                 $this->lazyMasterHandle = $conn;
 305         }
 306
 307         /**
 308          * @return IDatabase|null
 309          * @see setLazyMasterHandle()
 310          * @since 1.27
 311          */
 312         public function getLazyMasterHandle() {
 313                 return $this->lazyMasterHandle;
 314         }
 315
 316         /**
 317          * @return TransactionProfiler
 318          */
 319         protected function getTransactionProfiler() {
 320                 if ( !$this->trxProfiler ) {
 321                         $this->trxProfiler = new TransactionProfiler();
 322                 }
 323
 324                 return $this->trxProfiler;
 325         }
 326
 327         /**
 328          * @param TransactionProfiler $profiler
 329          * @since 1.27
 330          */
 331         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 332                 $this->trxProfiler = $profiler;
 333         }
 334
 335         /**
 336          * Returns true if this database supports (and uses) cascading deletes
 337          *
 338          * @return bool
 339          */
 340         public function cascadingDeletes() {
 341                 return false;
 342         }
 343
 344         /**
 345          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 346          *
 347          * @return bool
 348          */
 349         public function cleanupTriggers() {
 350                 return false;
 351         }
 352
 353         /**
 354          * Returns true if this database is strict about what can be put into an IP field.
 355          * Specifically, it uses a NULL value instead of an empty string.
 356          *
 357          * @return bool
 358          */
 359         public function strictIPs() {
 360                 return false;
 361         }
 362
 363         /**
 364          * Returns true if this database uses timestamps rather than integers
 365          *
 366          * @return bool
 367          */
 368         public function realTimestamps() {
 369                 return false;
 370         }
 371
 372         public function implicitGroupby() {
 373                 return true;
 374         }
 375
 376         public function implicitOrderby() {
 377                 return true;
 378         }
 379
 380         /**
 381          * Returns true if this database can do a native search on IP columns
 382          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 383          *
 384          * @return bool
 385          */
 386         public function searchableIPs() {
 387                 return false;
 388         }
 389
 390         /**
 391          * Returns true if this database can use functional indexes
 392          *
 393          * @return bool
 394          */
 395         public function functionalIndexes() {
 396                 return false;
 397         }
 398
 399         public function lastQuery() {
 400                 return $this->mLastQuery;
 401         }
 402
 403         public function doneWrites() {
 404                 return (bool)$this->mDoneWrites;
 405         }
 406
 407         public function lastDoneWrites() {
 408                 return $this->mDoneWrites ?: false;
 409         }
 410
 411         public function writesPending() {
 412                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 413         }
 414
 415         public function writesOrCallbacksPending() {
 416                 return $this->mTrxLevel && (
 417                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 418                 );
 419         }
 420
 421         public function pendingWriteQueryDuration() {
 422                 return $this->mTrxLevel ? $this->mTrxWriteDuration : false;
 423         }
 424
 425         public function pendingWriteCallers() {
 426                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 427         }
 428
 429         public function isOpen() {
 430                 return $this->mOpened;
 431         }
 432
 433         public function setFlag( $flag ) {
 434                 $this->mFlags |= $flag;
 435         }
 436
 437         public function clearFlag( $flag ) {
 438                 $this->mFlags &= ~$flag;
 439         }
 440
 441         public function getFlag( $flag ) {
 442                 return !!( $this->mFlags & $flag );
 443         }
 444
 445         public function getProperty( $name ) {
 446                 return $this->$name;
 447         }
 448
 449         public function getWikiID() {
 450                 if ( $this->mTablePrefix ) {
 451                         return "{$this->mDBname}-{$this->mTablePrefix}";
 452                 } else {
 453                         return $this->mDBname;
 454                 }
 455         }
 456
 457         /**
 458          * Return a path to the DBMS-specific SQL file if it exists,
 459          * otherwise default SQL file
 460          *
 461          * @param string $filename
 462          * @return string
 463          */
 464         private function getSqlFilePath( $filename ) {
 465                 global $IP;
 466                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 467                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 468                         return $dbmsSpecificFilePath;
 469                 } else {
 470                         return "$IP/maintenance/$filename";
 471                 }
 472         }
 473
 474         /**
 475          * Return a path to the DBMS-specific schema file,
 476          * otherwise default to tables.sql
 477          *
 478          * @return string
 479          */
 480         public function getSchemaPath() {
 481                 return $this->getSqlFilePath( 'tables.sql' );
 482         }
 483
 484         /**
 485          * Return a path to the DBMS-specific update key file,
 486          * otherwise default to update-keys.sql
 487          *
 488          * @return string
 489          */
 490         public function getUpdateKeysPath() {
 491                 return $this->getSqlFilePath( 'update-keys.sql' );
 492         }
 493
 494         /**
 495          * Get information about an index into an object
 496          * @param string $table Table name
 497          * @param string $index Index name
 498          * @param string $fname Calling function name
 499          * @return mixed Database-specific index description class or false if the index does not exist
 500          */
 501         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 502
 503         /**
 504          * Wrapper for addslashes()
 505          *
 506          * @param string $s String to be slashed.
 507          * @return string Slashed string.
 508          */
 509         abstract function strencode( $s );
 510
 511         /**
 512          * Constructor.
 513          *
 514          * FIXME: It is possible to construct a Database object with no associated
 515          * connection object, by specifying no parameters to __construct(). This
 516          * feature is deprecated and should be removed.
 517          *
 518          * DatabaseBase subclasses should not be constructed directly in external
 519          * code. DatabaseBase::factory() should be used instead.
 520          *
 521          * @param array $params Parameters passed from DatabaseBase::factory()
 522          */
 523         function __construct( array $params ) {
 524                 global $wgDBprefix, $wgDBmwschema, $wgCommandLineMode;
 525
 526                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 527
 528                 $server = $params['host'];
 529                 $user = $params['user'];
 530                 $password = $params['password'];
 531                 $dbName = $params['dbname'];
 532                 $flags = $params['flags'];
 533                 $tablePrefix = $params['tablePrefix'];
 534                 $schema = $params['schema'];
 535                 $foreign = $params['foreign'];
 536
 537                 $this->mFlags = $flags;
 538                 if ( $this->mFlags & DBO_DEFAULT ) {
 539                         if ( $wgCommandLineMode ) {
 540                                 $this->mFlags &= ~DBO_TRX;
 541                         } else {
 542                                 $this->mFlags |= DBO_TRX;
 543                         }
 544                 }
 545
 546                 $this->mSessionVars = $params['variables'];
 547
 548                 /** Get the default table prefix*/
 549                 if ( $tablePrefix === 'get from global' ) {
 550                         $this->mTablePrefix = $wgDBprefix;
 551                 } else {
 552                         $this->mTablePrefix = $tablePrefix;
 553                 }
 554
 555                 /** Get the database schema*/
 556                 if ( $schema === 'get from global' ) {
 557                         $this->mSchema = $wgDBmwschema;
 558                 } else {
 559                         $this->mSchema = $schema;
 560                 }
 561
 562                 $this->mForeign = $foreign;
 563
 564                 if ( isset( $params['trxProfiler'] ) ) {
 565                         $this->trxProfiler = $params['trxProfiler']; // override
 566                 }
 567
 568                 if ( $user ) {
 569                         $this->open( $server, $user, $password, $dbName );
 570                 }
 571         }
 572
 573         /**
 574          * Called by serialize. Throw an exception when DB connection is serialized.
 575          * This causes problems on some database engines because the connection is
 576          * not restored on unserialize.
 577          */
 578         public function __sleep() {
 579                 throw new MWException( 'Database serialization may cause problems, since ' .
 580                         'the connection is not restored on wakeup.' );
 581         }
 582
 583         /**
 584          * Given a DB type, construct the name of the appropriate child class of
 585          * DatabaseBase. This is designed to replace all of the manual stuff like:
 586          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 587          * as well as validate against the canonical list of DB types we have
 588          *
 589          * This factory function is mostly useful for when you need to connect to a
 590          * database other than the MediaWiki default (such as for external auth,
 591          * an extension, et cetera). Do not use this to connect to the MediaWiki
 592          * database. Example uses in core:
 593          * @see LoadBalancer::reallyOpenConnection()
 594          * @see ForeignDBRepo::getMasterDB()
 595          * @see WebInstallerDBConnect::execute()
 596          *
 597          * @since 1.18
 598          *
 599          * @param string $dbType A possible DB type
 600          * @param array $p An array of options to pass to the constructor.
 601          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 602          * @throws MWException If the database driver or extension cannot be found
 603          * @return DatabaseBase|null DatabaseBase subclass or null
 604          */
 605         final public static function factory( $dbType, $p = [] ) {
 606                 $canonicalDBTypes = [
 607                         'mysql' => [ 'mysqli', 'mysql' ],
 608                         'postgres' => [],
 609                         'sqlite' => [],
 610                         'oracle' => [],
 611                         'mssql' => [],
 612                 ];
 613
 614                 $driver = false;
 615                 $dbType = strtolower( $dbType );
 616                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 617                         $possibleDrivers = $canonicalDBTypes[$dbType];
 618                         if ( !empty( $p['driver'] ) ) {
 619                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 620                                         $driver = $p['driver'];
 621                                 } else {
 622                                         throw new MWException( __METHOD__ .
 623                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 624                                 }
 625                         } else {
 626                                 foreach ( $possibleDrivers as $posDriver ) {
 627                                         if ( extension_loaded( $posDriver ) ) {
 628                                                 $driver = $posDriver;
 629                                                 break;
 630                                         }
 631                                 }
 632                         }
 633                 } else {
 634                         $driver = $dbType;
 635                 }
 636                 if ( $driver === false ) {
 637                         throw new MWException( __METHOD__ .
 638                                 " no viable database extension found for type '$dbType'" );
 639                 }
 640
 641                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 642                 // and everything else doesn't use a schema (e.g. null)
 643                 // Although postgres and oracle support schemas, we don't use them (yet)
 644                 // to maintain backwards compatibility
 645                 $defaultSchemas = [
 646                         'mssql' => 'get from global',
 647                 ];
 648
 649                 $class = 'Database' . ucfirst( $driver );
 650                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 651                         // Resolve some defaults for b/c
 652                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 653                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 654                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 655                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 656                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 657                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 658                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 659                         if ( !isset( $p['schema'] ) ) {
 660                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 661                         }
 662                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 663
 664                         return new $class( $p );
 665                 } else {
 666                         return null;
 667                 }
 668         }
 669
 670         protected function installErrorHandler() {
 671                 $this->mPHPError = false;
 672                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 673                 set_error_handler( [ $this, 'connectionErrorHandler' ] );
 674         }
 675
 676         /**
 677          * @return bool|string
 678          */
 679         protected function restoreErrorHandler() {
 680                 restore_error_handler();
 681                 if ( $this->htmlErrors !== false ) {
 682                         ini_set( 'html_errors', $this->htmlErrors );
 683                 }
 684                 if ( $this->mPHPError ) {
 685                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 686                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 687
 688                         return $error;
 689                 } else {
 690                         return false;
 691                 }
 692         }
 693
 694         /**
 695          * @param int $errno
 696          * @param string $errstr
 697          */
 698         public function connectionErrorHandler( $errno, $errstr ) {
 699                 $this->mPHPError = $errstr;
 700         }
 701
 702         /**
 703          * Create a log context to pass to wfLogDBError or other logging functions.
 704          *
 705          * @param array $extras Additional data to add to context
 706          * @return array
 707          */
 708         protected function getLogContext( array $extras = [] ) {
 709                 return array_merge(
 710                         [
 711                                 'db_server' => $this->mServer,
 712                                 'db_name' => $this->mDBname,
 713                                 'db_user' => $this->mUser,
 714                         ],
 715                         $extras
 716                 );
 717         }
 718
 719         public function close() {
 720                 if ( $this->mConn ) {
 721                         if ( $this->trxLevel() ) {
 722                                 if ( !$this->mTrxAutomatic ) {
 723                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 724                                                 " performing implicit commit before closing connection!" );
 725                                 }
 726
 727                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 728                         }
 729
 730                         $closed = $this->closeConnection();
 731                         $this->mConn = false;
 732                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 733                         throw new MWException( "Transaction callbacks still pending." );
 734                 } else {
 735                         $closed = true;
 736                 }
 737                 $this->mOpened = false;
 738
 739                 return $closed;
 740         }
 741
 742         /**
 743          * Make sure isOpen() returns true as a sanity check
 744          *
 745          * @throws DBUnexpectedError
 746          */
 747         protected function assertOpen() {
 748                 if ( !$this->isOpen() ) {
 749                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 750                 }
 751         }
 752
 753         /**
 754          * Closes underlying database connection
 755          * @since 1.20
 756          * @return bool Whether connection was closed successfully
 757          */
 758         abstract protected function closeConnection();
 759
 760         function reportConnectionError( $error = 'Unknown error' ) {
 761                 $myError = $this->lastError();
 762                 if ( $myError ) {
 763                         $error = $myError;
 764                 }
 765
 766                 # New method
 767                 throw new DBConnectionError( $this, $error );
 768         }
 769
 770         /**
 771          * The DBMS-dependent part of query()
 772          *
 773          * @param string $sql SQL query.
 774          * @return ResultWrapper|bool Result object to feed to fetchObject,
 775          *   fetchRow, ...; or false on failure
 776          */
 777         abstract protected function doQuery( $sql );
 778
 779         /**
 780          * Determine whether a query writes to the DB.
 781          * Should return true if unsure.
 782          *
 783          * @param string $sql
 784          * @return bool
 785          */
 786         protected function isWriteQuery( $sql ) {
 787                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 788         }
 789
 790         /**
 791          * Determine whether a SQL statement is sensitive to isolation level.
 792          * A SQL statement is considered transactable if its result could vary
 793          * depending on the transaction isolation level. Operational commands
 794          * such as 'SET' and 'SHOW' are not considered to be transactable.
 795          *
 796          * @param string $sql
 797          * @return bool
 798          */
 799         protected function isTransactableQuery( $sql ) {
 800                 $verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
 801                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ] );
 802         }
 803
 804         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 805                 global $wgUser;
 806
 807                 $priorWritesPending = $this->writesOrCallbacksPending();
 808                 $this->mLastQuery = $sql;
 809
 810                 $isWrite = $this->isWriteQuery( $sql );
 811                 if ( $isWrite ) {
 812                         $reason = $this->getReadOnlyReason();
 813                         if ( $reason !== false ) {
 814                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 815                         }
 816                         # Set a flag indicating that writes have been done
 817                         $this->mDoneWrites = microtime( true );
 818                 }
 819
 820                 # Add a comment for easy SHOW PROCESSLIST interpretation
 821                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 822                         $userName = $wgUser->getName();
 823                         if ( mb_strlen( $userName ) > 15 ) {
 824                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 825                         }
 826                         $userName = str_replace( '/', '', $userName );
 827                 } else {
 828                         $userName = '';
 829                 }
 830
 831                 // Add trace comment to the begin of the sql string, right after the operator.
 832                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 833                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 834
 835                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 836                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 837                         && $this->isTransactableQuery( $sql )
 838                 ) {
 839                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 840                         $this->mTrxAutomatic = true;
 841                 }
 842
 843                 # Keep track of whether the transaction has write queries pending
 844                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 845                         $this->mTrxDoneWrites = true;
 846                         $this->getTransactionProfiler()->transactionWritingIn(
 847                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 848                 }
 849
 850                 if ( $this->debug() ) {
 851                         wfDebugLog( 'queries', sprintf( "%s: %s", $this->mDBname, $commentedSql ) );
 852                 }
 853
 854                 # Avoid fatals if close() was called
 855                 $this->assertOpen();
 856
 857                 # Send the query to the server
 858                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 859
 860                 # Try reconnecting if the connection was lost
 861                 if ( false === $ret && $this->wasErrorReissuable() ) {
 862                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 863                         # Stash the last error values before anything might clear them
 864                         $lastError = $this->lastError();
 865                         $lastErrno = $this->lastErrno();
 866                         # Update state tracking to reflect transaction loss due to disconnection
 867                         $this->handleTransactionLoss();
 868                         wfDebug( "Connection lost, reconnecting...\n" );
 869                         if ( $this->reconnect() ) {
 870                                 wfDebug( "Reconnected\n" );
 871                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 872                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
 873
 874                                 if ( !$recoverable ) {
 875                                         # Callers may catch the exception and continue to use the DB
 876                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 877                                 } else {
 878                                         # Should be safe to silently retry the query
 879                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 880                                 }
 881                         } else {
 882                                 wfDebug( "Failed\n" );
 883                         }
 884                 }
 885
 886                 if ( false === $ret ) {
 887                         # Deadlocks cause the entire transaction to abort, not just the statement.
 888                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 889                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 890                         if ( $this->wasDeadlock() ) {
 891                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 892                                         $tempIgnore = false; // not recoverable
 893                                 }
 894                                 # Update state tracking to reflect transaction loss
 895                                 $this->handleTransactionLoss();
 896                         }
 897
 898                         $this->reportQueryError(
 899                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 900                 }
 901
 902                 $res = $this->resultObject( $ret );
 903
 904                 return $res;
 905         }
 906
 907         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 908                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 909                 # generalizeSQL() will probably cut down the query to reasonable
 910                 # logging size most of the time. The substr is really just a sanity check.
 911                 if ( $isMaster ) {
 912                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 913                 } else {
 914                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 915                 }
 916
 917                 # Include query transaction state
 918                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 919
 920                 $profiler = Profiler::instance();
 921                 if ( !( $profiler instanceof ProfilerStub ) ) {
 922                         $queryProfSection = $profiler->scopedProfileIn( $queryProf );
 923                 }
 924
 925                 $startTime = microtime( true );
 926                 $ret = $this->doQuery( $commentedSql );
 927                 $queryRuntime = microtime( true ) - $startTime;
 928
 929                 unset( $queryProfSection ); // profile out (if set)
 930
 931                 if ( $ret !== false ) {
 932                         $this->lastPing = $startTime;
 933                         if ( $isWrite && $this->mTrxLevel ) {
 934                                 $this->mTrxWriteDuration += $queryRuntime;
 935                                 $this->mTrxWriteCallers[] = $fname;
 936                         }
 937                 }
 938
 939                 $this->getTransactionProfiler()->recordQueryCompletion(
 940                         $queryProf, $startTime, $isWrite, $this->affectedRows()
 941                 );
 942                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
 943
 944                 return $ret;
 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                         return null;
 975                 } catch ( Exception $e ) {
 976                         // Already logged; move on...
 977                         return $e;
 978                 }
 979         }
 980
 981         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 982                 if ( $this->ignoreErrors() || $tempIgnore ) {
 983                         wfDebug( "SQL ERROR (ignored): $error\n" );
 984                 } else {
 985                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
 986                         wfLogDBError(
 987                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
 988                                 $this->getLogContext( [
 989                                         'method' => __METHOD__,
 990                                         'errno' => $errno,
 991                                         'error' => $error,
 992                                         'sql1line' => $sql1line,
 993                                         'fname' => $fname,
 994                                 ] )
 995                         );
 996                         wfDebug( "SQL ERROR: " . $error . "\n" );
 997                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 998                 }
 999         }
1000
1001         /**
1002          * Intended to be compatible with the PEAR::DB wrapper functions.
1003          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1004          *
1005          * ? = scalar value, quoted as necessary
1006          * ! = raw SQL bit (a function for instance)
1007          * & = filename; reads the file and inserts as a blob
1008          *     (we don't use this though...)
1009          *
1010          * @param string $sql
1011          * @param string $func
1012          *
1013          * @return array
1014          */
1015         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1016                 /* MySQL doesn't support prepared statements (yet), so just
1017                  * pack up the query for reference. We'll manually replace
1018                  * the bits later.
1019                  */
1020                 return [ 'query' => $sql, 'func' => $func ];
1021         }
1022
1023         /**
1024          * Free a prepared query, generated by prepare().
1025          * @param string $prepared
1026          */
1027         protected function freePrepared( $prepared ) {
1028                 /* No-op by default */
1029         }
1030
1031         /**
1032          * Execute a prepared query with the various arguments
1033          * @param string $prepared The prepared sql
1034          * @param mixed $args Either an array here, or put scalars as varargs
1035          *
1036          * @return ResultWrapper
1037          */
1038         public function execute( $prepared, $args = null ) {
1039                 if ( !is_array( $args ) ) {
1040                         # Pull the var args
1041                         $args = func_get_args();
1042                         array_shift( $args );
1043                 }
1044
1045                 $sql = $this->fillPrepared( $prepared['query'], $args );
1046
1047                 return $this->query( $sql, $prepared['func'] );
1048         }
1049
1050         /**
1051          * For faking prepared SQL statements on DBs that don't support it directly.
1052          *
1053          * @param string $preparedQuery A 'preparable' SQL statement
1054          * @param array $args Array of Arguments to fill it with
1055          * @return string Executable SQL
1056          */
1057         public function fillPrepared( $preparedQuery, $args ) {
1058                 reset( $args );
1059                 $this->preparedArgs =& $args;
1060
1061                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1062                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1063         }
1064
1065         /**
1066          * preg_callback func for fillPrepared()
1067          * The arguments should be in $this->preparedArgs and must not be touched
1068          * while we're doing this.
1069          *
1070          * @param array $matches
1071          * @throws DBUnexpectedError
1072          * @return string
1073          */
1074         protected function fillPreparedArg( $matches ) {
1075                 switch ( $matches[1] ) {
1076                         case '\\?':
1077                                 return '?';
1078                         case '\\!':
1079                                 return '!';
1080                         case '\\&':
1081                                 return '&';
1082                 }
1083
1084                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1085
1086                 switch ( $matches[1] ) {
1087                         case '?':
1088                                 return $this->addQuotes( $arg );
1089                         case '!':
1090                                 return $arg;
1091                         case '&':
1092                                 # return $this->addQuotes( file_get_contents( $arg ) );
1093                                 throw new DBUnexpectedError(
1094                                         $this,
1095                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1096                                 );
1097                         default:
1098                                 throw new DBUnexpectedError(
1099                                         $this,
1100                                         'Received invalid match. This should never happen!'
1101                                 );
1102                 }
1103         }
1104
1105         public function freeResult( $res ) {
1106         }
1107
1108         public function selectField(
1109                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1110         ) {
1111                 if ( $var === '*' ) { // sanity
1112                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1113                 }
1114
1115                 if ( !is_array( $options ) ) {
1116                         $options = [ $options ];
1117                 }
1118
1119                 $options['LIMIT'] = 1;
1120
1121                 $res = $this->select( $table, $var, $cond, $fname, $options );
1122                 if ( $res === false || !$this->numRows( $res ) ) {
1123                         return false;
1124                 }
1125
1126                 $row = $this->fetchRow( $res );
1127
1128                 if ( $row !== false ) {
1129                         return reset( $row );
1130                 } else {
1131                         return false;
1132                 }
1133         }
1134
1135         public function selectFieldValues(
1136                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1137         ) {
1138                 if ( $var === '*' ) { // sanity
1139                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1140                 } elseif ( !is_string( $var ) ) { // sanity
1141                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1142                 }
1143
1144                 if ( !is_array( $options ) ) {
1145                         $options = [ $options ];
1146                 }
1147
1148                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1149                 if ( $res === false ) {
1150                         return false;
1151                 }
1152
1153                 $values = [];
1154                 foreach ( $res as $row ) {
1155                         $values[] = $row->$var;
1156                 }
1157
1158                 return $values;
1159         }
1160
1161         /**
1162          * Returns an optional USE INDEX clause to go after the table, and a
1163          * string to go at the end of the query.
1164          *
1165          * @param array $options Associative array of options to be turned into
1166          *   an SQL query, valid keys are listed in the function.
1167          * @return array
1168          * @see DatabaseBase::select()
1169          */
1170         public function makeSelectOptions( $options ) {
1171                 $preLimitTail = $postLimitTail = '';
1172                 $startOpts = '';
1173
1174                 $noKeyOptions = [];
1175
1176                 foreach ( $options as $key => $option ) {
1177                         if ( is_numeric( $key ) ) {
1178                                 $noKeyOptions[$option] = true;
1179                         }
1180                 }
1181
1182                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1183
1184                 $preLimitTail .= $this->makeOrderBy( $options );
1185
1186                 // if (isset($options['LIMIT'])) {
1187                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1188                 //              isset($options['OFFSET']) ? $options['OFFSET']
1189                 //              : false);
1190                 // }
1191
1192                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1193                         $postLimitTail .= ' FOR UPDATE';
1194                 }
1195
1196                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1197                         $postLimitTail .= ' LOCK IN SHARE MODE';
1198                 }
1199
1200                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1201                         $startOpts .= 'DISTINCT';
1202                 }
1203
1204                 # Various MySQL extensions
1205                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1206                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1207                 }
1208
1209                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1210                         $startOpts .= ' HIGH_PRIORITY';
1211                 }
1212
1213                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1214                         $startOpts .= ' SQL_BIG_RESULT';
1215                 }
1216
1217                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1218                         $startOpts .= ' SQL_BUFFER_RESULT';
1219                 }
1220
1221                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1222                         $startOpts .= ' SQL_SMALL_RESULT';
1223                 }
1224
1225                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1226                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1227                 }
1228
1229                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1230                         $startOpts .= ' SQL_CACHE';
1231                 }
1232
1233                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1234                         $startOpts .= ' SQL_NO_CACHE';
1235                 }
1236
1237                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1238                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1239                 } else {
1240                         $useIndex = '';
1241                 }
1242
1243                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail ];
1244         }
1245
1246         /**
1247          * Returns an optional GROUP BY with an optional HAVING
1248          *
1249          * @param array $options Associative array of options
1250          * @return string
1251          * @see DatabaseBase::select()
1252          * @since 1.21
1253          */
1254         public function makeGroupByWithHaving( $options ) {
1255                 $sql = '';
1256                 if ( isset( $options['GROUP BY'] ) ) {
1257                         $gb = is_array( $options['GROUP BY'] )
1258                                 ? implode( ',', $options['GROUP BY'] )
1259                                 : $options['GROUP BY'];
1260                         $sql .= ' GROUP BY ' . $gb;
1261                 }
1262                 if ( isset( $options['HAVING'] ) ) {
1263                         $having = is_array( $options['HAVING'] )
1264                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1265                                 : $options['HAVING'];
1266                         $sql .= ' HAVING ' . $having;
1267                 }
1268
1269                 return $sql;
1270         }
1271
1272         /**
1273          * Returns an optional ORDER BY
1274          *
1275          * @param array $options Associative array of options
1276          * @return string
1277          * @see DatabaseBase::select()
1278          * @since 1.21
1279          */
1280         public function makeOrderBy( $options ) {
1281                 if ( isset( $options['ORDER BY'] ) ) {
1282                         $ob = is_array( $options['ORDER BY'] )
1283                                 ? implode( ',', $options['ORDER BY'] )
1284                                 : $options['ORDER BY'];
1285
1286                         return ' ORDER BY ' . $ob;
1287                 }
1288
1289                 return '';
1290         }
1291
1292         // See IDatabase::select for the docs for this function
1293         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1294                 $options = [], $join_conds = [] ) {
1295                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1296
1297                 return $this->query( $sql, $fname );
1298         }
1299
1300         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1301                 $options = [], $join_conds = []
1302         ) {
1303                 if ( is_array( $vars ) ) {
1304                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1305                 }
1306
1307                 $options = (array)$options;
1308                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1309                         ? $options['USE INDEX']
1310                         : [];
1311
1312                 if ( is_array( $table ) ) {
1313                         $from = ' FROM ' .
1314                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1315                 } elseif ( $table != '' ) {
1316                         if ( $table[0] == ' ' ) {
1317                                 $from = ' FROM ' . $table;
1318                         } else {
1319                                 $from = ' FROM ' .
1320                                         $this->tableNamesWithUseIndexOrJOIN( [ $table ], $useIndexes, [] );
1321                         }
1322                 } else {
1323                         $from = '';
1324                 }
1325
1326                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1327                         $this->makeSelectOptions( $options );
1328
1329                 if ( !empty( $conds ) ) {
1330                         if ( is_array( $conds ) ) {
1331                                 $conds = $this->makeList( $conds, LIST_AND );
1332                         }
1333                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1334                 } else {
1335                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1336                 }
1337
1338                 if ( isset( $options['LIMIT'] ) ) {
1339                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1340                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1341                 }
1342                 $sql = "$sql $postLimitTail";
1343
1344                 if ( isset( $options['EXPLAIN'] ) ) {
1345                         $sql = 'EXPLAIN ' . $sql;
1346                 }
1347
1348                 return $sql;
1349         }
1350
1351         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1352                 $options = [], $join_conds = []
1353         ) {
1354                 $options = (array)$options;
1355                 $options['LIMIT'] = 1;
1356                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1357
1358                 if ( $res === false ) {
1359                         return false;
1360                 }
1361
1362                 if ( !$this->numRows( $res ) ) {
1363                         return false;
1364                 }
1365
1366                 $obj = $this->fetchObject( $res );
1367
1368                 return $obj;
1369         }
1370
1371         public function estimateRowCount(
1372                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1373         ) {
1374                 $rows = 0;
1375                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1376
1377                 if ( $res ) {
1378                         $row = $this->fetchRow( $res );
1379                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1380                 }
1381
1382                 return $rows;
1383         }
1384
1385         public function selectRowCount(
1386                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1387         ) {
1388                 $rows = 0;
1389                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1390                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1391
1392                 if ( $res ) {
1393                         $row = $this->fetchRow( $res );
1394                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1395                 }
1396
1397                 return $rows;
1398         }
1399
1400         /**
1401          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1402          * It's only slightly flawed. Don't use for anything important.
1403          *
1404          * @param string $sql A SQL Query
1405          *
1406          * @return string
1407          */
1408         protected static function generalizeSQL( $sql ) {
1409                 # This does the same as the regexp below would do, but in such a way
1410                 # as to avoid crashing php on some large strings.
1411                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1412
1413                 $sql = str_replace( "\\\\", '', $sql );
1414                 $sql = str_replace( "\\'", '', $sql );
1415                 $sql = str_replace( "\\\"", '', $sql );
1416                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1417                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1418
1419                 # All newlines, tabs, etc replaced by single space
1420                 $sql = preg_replace( '/\s+/', ' ', $sql );
1421
1422                 # All numbers => N,
1423                 # except the ones surrounded by characters, e.g. l10n
1424                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1425                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1426
1427                 return $sql;
1428         }
1429
1430         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1431                 $info = $this->fieldInfo( $table, $field );
1432
1433                 return (bool)$info;
1434         }
1435
1436         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1437                 if ( !$this->tableExists( $table ) ) {
1438                         return null;
1439                 }
1440
1441                 $info = $this->indexInfo( $table, $index, $fname );
1442                 if ( is_null( $info ) ) {
1443                         return null;
1444                 } else {
1445                         return $info !== false;
1446                 }
1447         }
1448
1449         public function tableExists( $table, $fname = __METHOD__ ) {
1450                 $table = $this->tableName( $table );
1451                 $old = $this->ignoreErrors( true );
1452                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1453                 $this->ignoreErrors( $old );
1454
1455                 return (bool)$res;
1456         }
1457
1458         public function indexUnique( $table, $index ) {
1459                 $indexInfo = $this->indexInfo( $table, $index );
1460
1461                 if ( !$indexInfo ) {
1462                         return null;
1463                 }
1464
1465                 return !$indexInfo[0]->Non_unique;
1466         }
1467
1468         /**
1469          * Helper for DatabaseBase::insert().
1470          *
1471          * @param array $options
1472          * @return string
1473          */
1474         protected function makeInsertOptions( $options ) {
1475                 return implode( ' ', $options );
1476         }
1477
1478         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1479                 # No rows to insert, easy just return now
1480                 if ( !count( $a ) ) {
1481                         return true;
1482                 }
1483
1484                 $table = $this->tableName( $table );
1485
1486                 if ( !is_array( $options ) ) {
1487                         $options = [ $options ];
1488                 }
1489
1490                 $fh = null;
1491                 if ( isset( $options['fileHandle'] ) ) {
1492                         $fh = $options['fileHandle'];
1493                 }
1494                 $options = $this->makeInsertOptions( $options );
1495
1496                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1497                         $multi = true;
1498                         $keys = array_keys( $a[0] );
1499                 } else {
1500                         $multi = false;
1501                         $keys = array_keys( $a );
1502                 }
1503
1504                 $sql = 'INSERT ' . $options .
1505                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1506
1507                 if ( $multi ) {
1508                         $first = true;
1509                         foreach ( $a as $row ) {
1510                                 if ( $first ) {
1511                                         $first = false;
1512                                 } else {
1513                                         $sql .= ',';
1514                                 }
1515                                 $sql .= '(' . $this->makeList( $row ) . ')';
1516                         }
1517                 } else {
1518                         $sql .= '(' . $this->makeList( $a ) . ')';
1519                 }
1520
1521                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1522                         return false;
1523                 } elseif ( $fh !== null ) {
1524                         return true;
1525                 }
1526
1527                 return (bool)$this->query( $sql, $fname );
1528         }
1529
1530         /**
1531          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1532          *
1533          * @param array $options
1534          * @return array
1535          */
1536         protected function makeUpdateOptionsArray( $options ) {
1537                 if ( !is_array( $options ) ) {
1538                         $options = [ $options ];
1539                 }
1540
1541                 $opts = [];
1542
1543                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1544                         $opts[] = $this->lowPriorityOption();
1545                 }
1546
1547                 if ( in_array( 'IGNORE', $options ) ) {
1548                         $opts[] = 'IGNORE';
1549                 }
1550
1551                 return $opts;
1552         }
1553
1554         /**
1555          * Make UPDATE options for the DatabaseBase::update function
1556          *
1557          * @param array $options The options passed to DatabaseBase::update
1558          * @return string
1559          */
1560         protected function makeUpdateOptions( $options ) {
1561                 $opts = $this->makeUpdateOptionsArray( $options );
1562
1563                 return implode( ' ', $opts );
1564         }
1565
1566         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1567                 $table = $this->tableName( $table );
1568                 $opts = $this->makeUpdateOptions( $options );
1569                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1570
1571                 if ( $conds !== [] && $conds !== '*' ) {
1572                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1573                 }
1574
1575                 return $this->query( $sql, $fname );
1576         }
1577
1578         public function makeList( $a, $mode = LIST_COMMA ) {
1579                 if ( !is_array( $a ) ) {
1580                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1581                 }
1582
1583                 $first = true;
1584                 $list = '';
1585
1586                 foreach ( $a as $field => $value ) {
1587                         if ( !$first ) {
1588                                 if ( $mode == LIST_AND ) {
1589                                         $list .= ' AND ';
1590                                 } elseif ( $mode == LIST_OR ) {
1591                                         $list .= ' OR ';
1592                                 } else {
1593                                         $list .= ',';
1594                                 }
1595                         } else {
1596                                 $first = false;
1597                         }
1598
1599                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1600                                 $list .= "($value)";
1601                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1602                                 $list .= "$value";
1603                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1604                                 // Remove null from array to be handled separately if found
1605                                 $includeNull = false;
1606                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1607                                         $includeNull = true;
1608                                         unset( $value[$nullKey] );
1609                                 }
1610                                 if ( count( $value ) == 0 && !$includeNull ) {
1611                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1612                                 } elseif ( count( $value ) == 0 ) {
1613                                         // only check if $field is null
1614                                         $list .= "$field IS NULL";
1615                                 } else {
1616                                         // IN clause contains at least one valid element
1617                                         if ( $includeNull ) {
1618                                                 // Group subconditions to ensure correct precedence
1619                                                 $list .= '(';
1620                                         }
1621                                         if ( count( $value ) == 1 ) {
1622                                                 // Special-case single values, as IN isn't terribly efficient
1623                                                 // Don't necessarily assume the single key is 0; we don't
1624                                                 // enforce linear numeric ordering on other arrays here.
1625                                                 $value = array_values( $value )[0];
1626                                                 $list .= $field . " = " . $this->addQuotes( $value );
1627                                         } else {
1628                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1629                                         }
1630                                         // if null present in array, append IS NULL
1631                                         if ( $includeNull ) {
1632                                                 $list .= " OR $field IS NULL)";
1633                                         }
1634                                 }
1635                         } elseif ( $value === null ) {
1636                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1637                                         $list .= "$field IS ";
1638                                 } elseif ( $mode == LIST_SET ) {
1639                                         $list .= "$field = ";
1640                                 }
1641                                 $list .= 'NULL';
1642                         } else {
1643                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1644                                         $list .= "$field = ";
1645                                 }
1646                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1647                         }
1648                 }
1649
1650                 return $list;
1651         }
1652
1653         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1654                 $conds = [];
1655
1656                 foreach ( $data as $base => $sub ) {
1657                         if ( count( $sub ) ) {
1658                                 $conds[] = $this->makeList(
1659                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1660                                         LIST_AND );
1661                         }
1662                 }
1663
1664                 if ( $conds ) {
1665                         return $this->makeList( $conds, LIST_OR );
1666                 } else {
1667                         // Nothing to search for...
1668                         return false;
1669                 }
1670         }
1671
1672         /**
1673          * Return aggregated value alias
1674          *
1675          * @param array $valuedata
1676          * @param string $valuename
1677          *
1678          * @return string
1679          */
1680         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1681                 return $valuename;
1682         }
1683
1684         public function bitNot( $field ) {
1685                 return "(~$field)";
1686         }
1687
1688         public function bitAnd( $fieldLeft, $fieldRight ) {
1689                 return "($fieldLeft & $fieldRight)";
1690         }
1691
1692         public function bitOr( $fieldLeft, $fieldRight ) {
1693                 return "($fieldLeft | $fieldRight)";
1694         }
1695
1696         public function buildConcat( $stringList ) {
1697                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1698         }
1699
1700         public function buildGroupConcatField(
1701                 $delim, $table, $field, $conds = '', $join_conds = []
1702         ) {
1703                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1704
1705                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1706         }
1707
1708         public function selectDB( $db ) {
1709                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1710                 # if your database engine supports a concept similar to MySQL's
1711                 # databases you may as well.
1712                 $this->mDBname = $db;
1713
1714                 return true;
1715         }
1716
1717         public function getDBname() {
1718                 return $this->mDBname;
1719         }
1720
1721         public function getServer() {
1722                 return $this->mServer;
1723         }
1724
1725         /**
1726          * Format a table name ready for use in constructing an SQL query
1727          *
1728          * This does two important things: it quotes the table names to clean them up,
1729          * and it adds a table prefix if only given a table name with no quotes.
1730          *
1731          * All functions of this object which require a table name call this function
1732          * themselves. Pass the canonical name to such functions. This is only needed
1733          * when calling query() directly.
1734          *
1735          * @note This function does not sanitize user input. It is not safe to use
1736          *   this function to escape user input.
1737          * @param string $name Database table name
1738          * @param string $format One of:
1739          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1740          *            so that it can be used in a query.
1741          *   raw - Do not add identifier quotes to the table name
1742          * @return string Full database name
1743          */
1744         public function tableName( $name, $format = 'quoted' ) {
1745                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1746                 # Skip the entire process when we have a string quoted on both ends.
1747                 # Note that we check the end so that we will still quote any use of
1748                 # use of `database`.table. But won't break things if someone wants
1749                 # to query a database table with a dot in the name.
1750                 if ( $this->isQuotedIdentifier( $name ) ) {
1751                         return $name;
1752                 }
1753
1754                 # Lets test for any bits of text that should never show up in a table
1755                 # name. Basically anything like JOIN or ON which are actually part of
1756                 # SQL queries, but may end up inside of the table value to combine
1757                 # sql. Such as how the API is doing.
1758                 # Note that we use a whitespace test rather than a \b test to avoid
1759                 # any remote case where a word like on may be inside of a table name
1760                 # surrounded by symbols which may be considered word breaks.
1761                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1762                         return $name;
1763                 }
1764
1765                 # Split database and table into proper variables.
1766                 # We reverse the explode so that database.table and table both output
1767                 # the correct table.
1768                 $dbDetails = explode( '.', $name, 3 );
1769                 if ( count( $dbDetails ) == 3 ) {
1770                         list( $database, $schema, $table ) = $dbDetails;
1771                         # We don't want any prefix added in this case
1772                         $prefix = '';
1773                 } elseif ( count( $dbDetails ) == 2 ) {
1774                         list( $database, $table ) = $dbDetails;
1775                         # We don't want any prefix added in this case
1776                         # In dbs that support it, $database may actually be the schema
1777                         # but that doesn't affect any of the functionality here
1778                         $prefix = '';
1779                         $schema = null;
1780                 } else {
1781                         list( $table ) = $dbDetails;
1782                         if ( $wgSharedDB !== null # We have a shared database
1783                                 && $this->mForeign == false # We're not working on a foreign database
1784                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1785                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1786                         ) {
1787                                 $database = $wgSharedDB;
1788                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1789                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1790                         } else {
1791                                 $database = null;
1792                                 $schema = $this->mSchema; # Default schema
1793                                 $prefix = $this->mTablePrefix; # Default prefix
1794                         }
1795                 }
1796
1797                 # Quote $table and apply the prefix if not quoted.
1798                 # $tableName might be empty if this is called from Database::replaceVars()
1799                 $tableName = "{$prefix}{$table}";
1800                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1801                         $tableName = $this->addIdentifierQuotes( $tableName );
1802                 }
1803
1804                 # Quote $schema and merge it with the table name if needed
1805                 if ( strlen( $schema ) ) {
1806                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1807                                 $schema = $this->addIdentifierQuotes( $schema );
1808                         }
1809                         $tableName = $schema . '.' . $tableName;
1810                 }
1811
1812                 # Quote $database and merge it with the table name if needed
1813                 if ( $database !== null ) {
1814                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1815                                 $database = $this->addIdentifierQuotes( $database );
1816                         }
1817                         $tableName = $database . '.' . $tableName;
1818                 }
1819
1820                 return $tableName;
1821         }
1822
1823         /**
1824          * Fetch a number of table names into an array
1825          * This is handy when you need to construct SQL for joins
1826          *
1827          * Example:
1828          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1829          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1830          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1831          *
1832          * @return array
1833          */
1834         public function tableNames() {
1835                 $inArray = func_get_args();
1836                 $retVal = [];
1837
1838                 foreach ( $inArray as $name ) {
1839                         $retVal[$name] = $this->tableName( $name );
1840                 }
1841
1842                 return $retVal;
1843         }
1844
1845         /**
1846          * Fetch a number of table names into an zero-indexed numerical array
1847          * This is handy when you need to construct SQL for joins
1848          *
1849          * Example:
1850          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1851          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1852          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1853          *
1854          * @return array
1855          */
1856         public function tableNamesN() {
1857                 $inArray = func_get_args();
1858                 $retVal = [];
1859
1860                 foreach ( $inArray as $name ) {
1861                         $retVal[] = $this->tableName( $name );
1862                 }
1863
1864                 return $retVal;
1865         }
1866
1867         /**
1868          * Get an aliased table name
1869          * e.g. tableName AS newTableName
1870          *
1871          * @param string $name Table name, see tableName()
1872          * @param string|bool $alias Alias (optional)
1873          * @return string SQL name for aliased table. Will not alias a table to its own name
1874          */
1875         public function tableNameWithAlias( $name, $alias = false ) {
1876                 if ( !$alias || $alias == $name ) {
1877                         return $this->tableName( $name );
1878                 } else {
1879                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1880                 }
1881         }
1882
1883         /**
1884          * Gets an array of aliased table names
1885          *
1886          * @param array $tables [ [alias] => table ]
1887          * @return string[] See tableNameWithAlias()
1888          */
1889         public function tableNamesWithAlias( $tables ) {
1890                 $retval = [];
1891                 foreach ( $tables as $alias => $table ) {
1892                         if ( is_numeric( $alias ) ) {
1893                                 $alias = $table;
1894                         }
1895                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1896                 }
1897
1898                 return $retval;
1899         }
1900
1901         /**
1902          * Get an aliased field name
1903          * e.g. fieldName AS newFieldName
1904          *
1905          * @param string $name Field name
1906          * @param string|bool $alias Alias (optional)
1907          * @return string SQL name for aliased field. Will not alias a field to its own name
1908          */
1909         public function fieldNameWithAlias( $name, $alias = false ) {
1910                 if ( !$alias || (string)$alias === (string)$name ) {
1911                         return $name;
1912                 } else {
1913                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
1914                 }
1915         }
1916
1917         /**
1918          * Gets an array of aliased field names
1919          *
1920          * @param array $fields [ [alias] => field ]
1921          * @return string[] See fieldNameWithAlias()
1922          */
1923         public function fieldNamesWithAlias( $fields ) {
1924                 $retval = [];
1925                 foreach ( $fields as $alias => $field ) {
1926                         if ( is_numeric( $alias ) ) {
1927                                 $alias = $field;
1928                         }
1929                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1930                 }
1931
1932                 return $retval;
1933         }
1934
1935         /**
1936          * Get the aliased table name clause for a FROM clause
1937          * which might have a JOIN and/or USE INDEX clause
1938          *
1939          * @param array $tables ( [alias] => table )
1940          * @param array $use_index Same as for select()
1941          * @param array $join_conds Same as for select()
1942          * @return string
1943          */
1944         protected function tableNamesWithUseIndexOrJOIN(
1945                 $tables, $use_index = [], $join_conds = []
1946         ) {
1947                 $ret = [];
1948                 $retJOIN = [];
1949                 $use_index = (array)$use_index;
1950                 $join_conds = (array)$join_conds;
1951
1952                 foreach ( $tables as $alias => $table ) {
1953                         if ( !is_string( $alias ) ) {
1954                                 // No alias? Set it equal to the table name
1955                                 $alias = $table;
1956                         }
1957                         // Is there a JOIN clause for this table?
1958                         if ( isset( $join_conds[$alias] ) ) {
1959                                 list( $joinType, $conds ) = $join_conds[$alias];
1960                                 $tableClause = $joinType;
1961                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1962                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1963                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1964                                         if ( $use != '' ) {
1965                                                 $tableClause .= ' ' . $use;
1966                                         }
1967                                 }
1968                                 $on = $this->makeList( (array)$conds, LIST_AND );
1969                                 if ( $on != '' ) {
1970                                         $tableClause .= ' ON (' . $on . ')';
1971                                 }
1972
1973                                 $retJOIN[] = $tableClause;
1974                         } elseif ( isset( $use_index[$alias] ) ) {
1975                                 // Is there an INDEX clause for this table?
1976                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1977                                 $tableClause .= ' ' . $this->useIndexClause(
1978                                         implode( ',', (array)$use_index[$alias] )
1979                                 );
1980
1981                                 $ret[] = $tableClause;
1982                         } else {
1983                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1984
1985                                 $ret[] = $tableClause;
1986                         }
1987                 }
1988
1989                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1990                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1991                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1992
1993                 // Compile our final table clause
1994                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
1995         }
1996
1997         /**
1998          * Get the name of an index in a given table.
1999          *
2000          * @param string $index
2001          * @return string
2002          */
2003         protected function indexName( $index ) {
2004                 // Backwards-compatibility hack
2005                 $renamed = [
2006                         'ar_usertext_timestamp' => 'usertext_timestamp',
2007                         'un_user_id' => 'user_id',
2008                         'un_user_ip' => 'user_ip',
2009                 ];
2010
2011                 if ( isset( $renamed[$index] ) ) {
2012                         return $renamed[$index];
2013                 } else {
2014                         return $index;
2015                 }
2016         }
2017
2018         public function addQuotes( $s ) {
2019                 if ( $s instanceof Blob ) {
2020                         $s = $s->fetch();
2021                 }
2022                 if ( $s === null ) {
2023                         return 'NULL';
2024                 } else {
2025                         # This will also quote numeric values. This should be harmless,
2026                         # and protects against weird problems that occur when they really
2027                         # _are_ strings such as article titles and string->number->string
2028                         # conversion is not 1:1.
2029                         return "'" . $this->strencode( $s ) . "'";
2030                 }
2031         }
2032
2033         /**
2034          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2035          * MySQL uses `backticks` while basically everything else uses double quotes.
2036          * Since MySQL is the odd one out here the double quotes are our generic
2037          * and we implement backticks in DatabaseMysql.
2038          *
2039          * @param string $s
2040          * @return string
2041          */
2042         public function addIdentifierQuotes( $s ) {
2043                 return '"' . str_replace( '"', '""', $s ) . '"';
2044         }
2045
2046         /**
2047          * Returns if the given identifier looks quoted or not according to
2048          * the database convention for quoting identifiers .
2049          *
2050          * @note Do not use this to determine if untrusted input is safe.
2051          *   A malicious user can trick this function.
2052          * @param string $name
2053          * @return bool
2054          */
2055         public function isQuotedIdentifier( $name ) {
2056                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2057         }
2058
2059         /**
2060          * @param string $s
2061          * @return string
2062          */
2063         protected function escapeLikeInternal( $s ) {
2064                 return addcslashes( $s, '\%_' );
2065         }
2066
2067         public function buildLike() {
2068                 $params = func_get_args();
2069
2070                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2071                         $params = $params[0];
2072                 }
2073
2074                 $s = '';
2075
2076                 foreach ( $params as $value ) {
2077                         if ( $value instanceof LikeMatch ) {
2078                                 $s .= $value->toString();
2079                         } else {
2080                                 $s .= $this->escapeLikeInternal( $value );
2081                         }
2082                 }
2083
2084                 return " LIKE {$this->addQuotes( $s )} ";
2085         }
2086
2087         public function anyChar() {
2088                 return new LikeMatch( '_' );
2089         }
2090
2091         public function anyString() {
2092                 return new LikeMatch( '%' );
2093         }
2094
2095         public function nextSequenceValue( $seqName ) {
2096                 return null;
2097         }
2098
2099         /**
2100          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2101          * is only needed because a) MySQL must be as efficient as possible due to
2102          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2103          * which index to pick. Anyway, other databases might have different
2104          * indexes on a given table. So don't bother overriding this unless you're
2105          * MySQL.
2106          * @param string $index
2107          * @return string
2108          */
2109         public function useIndexClause( $index ) {
2110                 return '';
2111         }
2112
2113         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2114                 $quotedTable = $this->tableName( $table );
2115
2116                 if ( count( $rows ) == 0 ) {
2117                         return;
2118                 }
2119
2120                 # Single row case
2121                 if ( !is_array( reset( $rows ) ) ) {
2122                         $rows = [ $rows ];
2123                 }
2124
2125                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2126                 foreach ( $rows as $row ) {
2127                         # Delete rows which collide
2128                         if ( $uniqueIndexes ) {
2129                                 $sql = "DELETE FROM $quotedTable WHERE ";
2130                                 $first = true;
2131                                 foreach ( $uniqueIndexes as $index ) {
2132                                         if ( $first ) {
2133                                                 $first = false;
2134                                                 $sql .= '( ';
2135                                         } else {
2136                                                 $sql .= ' ) OR ( ';
2137                                         }
2138                                         if ( is_array( $index ) ) {
2139                                                 $first2 = true;
2140                                                 foreach ( $index as $col ) {
2141                                                         if ( $first2 ) {
2142                                                                 $first2 = false;
2143                                                         } else {
2144                                                                 $sql .= ' AND ';
2145                                                         }
2146                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2147                                                 }
2148                                         } else {
2149                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2150                                         }
2151                                 }
2152                                 $sql .= ' )';
2153                                 $this->query( $sql, $fname );
2154                         }
2155
2156                         # Now insert the row
2157                         $this->insert( $table, $row, $fname );
2158                 }
2159         }
2160
2161         /**
2162          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2163          * statement.
2164          *
2165          * @param string $table Table name
2166          * @param array|string $rows Row(s) to insert
2167          * @param string $fname Caller function name
2168          *
2169          * @return ResultWrapper
2170          */
2171         protected function nativeReplace( $table, $rows, $fname ) {
2172                 $table = $this->tableName( $table );
2173
2174                 # Single row case
2175                 if ( !is_array( reset( $rows ) ) ) {
2176                         $rows = [ $rows ];
2177                 }
2178
2179                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2180                 $first = true;
2181
2182                 foreach ( $rows as $row ) {
2183                         if ( $first ) {
2184                                 $first = false;
2185                         } else {
2186                                 $sql .= ',';
2187                         }
2188
2189                         $sql .= '(' . $this->makeList( $row ) . ')';
2190                 }
2191
2192                 return $this->query( $sql, $fname );
2193         }
2194
2195         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2196                 $fname = __METHOD__
2197         ) {
2198                 if ( !count( $rows ) ) {
2199                         return true; // nothing to do
2200                 }
2201
2202                 if ( !is_array( reset( $rows ) ) ) {
2203                         $rows = [ $rows ];
2204                 }
2205
2206                 if ( count( $uniqueIndexes ) ) {
2207                         $clauses = []; // list WHERE clauses that each identify a single row
2208                         foreach ( $rows as $row ) {
2209                                 foreach ( $uniqueIndexes as $index ) {
2210                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2211                                         $rowKey = []; // unique key to this row
2212                                         foreach ( $index as $column ) {
2213                                                 $rowKey[$column] = $row[$column];
2214                                         }
2215                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2216                                 }
2217                         }
2218                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2219                 } else {
2220                         $where = false;
2221                 }
2222
2223                 $useTrx = !$this->mTrxLevel;
2224                 if ( $useTrx ) {
2225                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2226                 }
2227                 try {
2228                         # Update any existing conflicting row(s)
2229                         if ( $where !== false ) {
2230                                 $ok = $this->update( $table, $set, $where, $fname );
2231                         } else {
2232                                 $ok = true;
2233                         }
2234                         # Now insert any non-conflicting row(s)
2235                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2236                 } catch ( Exception $e ) {
2237                         if ( $useTrx ) {
2238                                 $this->rollback( $fname );
2239                         }
2240                         throw $e;
2241                 }
2242                 if ( $useTrx ) {
2243                         $this->commit( $fname, self::TRANSACTION_INTERNAL );
2244                 }
2245
2246                 return $ok;
2247         }
2248
2249         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2250                 $fname = __METHOD__
2251         ) {
2252                 if ( !$conds ) {
2253                         throw new DBUnexpectedError( $this,
2254                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2255                 }
2256
2257                 $delTable = $this->tableName( $delTable );
2258                 $joinTable = $this->tableName( $joinTable );
2259                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2260                 if ( $conds != '*' ) {
2261                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2262                 }
2263                 $sql .= ')';
2264
2265                 $this->query( $sql, $fname );
2266         }
2267
2268         /**
2269          * Returns the size of a text field, or -1 for "unlimited"
2270          *
2271          * @param string $table
2272          * @param string $field
2273          * @return int
2274          */
2275         public function textFieldSize( $table, $field ) {
2276                 $table = $this->tableName( $table );
2277                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2278                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2279                 $row = $this->fetchObject( $res );
2280
2281                 $m = [];
2282
2283                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2284                         $size = $m[1];
2285                 } else {
2286                         $size = -1;
2287                 }
2288
2289                 return $size;
2290         }
2291
2292         /**
2293          * A string to insert into queries to show that they're low-priority, like
2294          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2295          * string and nothing bad should happen.
2296          *
2297          * @return string Returns the text of the low priority option if it is
2298          *   supported, or a blank string otherwise
2299          */
2300         public function lowPriorityOption() {
2301                 return '';
2302         }
2303
2304         public function delete( $table, $conds, $fname = __METHOD__ ) {
2305                 if ( !$conds ) {
2306                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2307                 }
2308
2309                 $table = $this->tableName( $table );
2310                 $sql = "DELETE FROM $table";
2311
2312                 if ( $conds != '*' ) {
2313                         if ( is_array( $conds ) ) {
2314                                 $conds = $this->makeList( $conds, LIST_AND );
2315                         }
2316                         $sql .= ' WHERE ' . $conds;
2317                 }
2318
2319                 return $this->query( $sql, $fname );
2320         }
2321
2322         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2323                 $fname = __METHOD__,
2324                 $insertOptions = [], $selectOptions = []
2325         ) {
2326                 $destTable = $this->tableName( $destTable );
2327
2328                 if ( !is_array( $insertOptions ) ) {
2329                         $insertOptions = [ $insertOptions ];
2330                 }
2331
2332                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2333
2334                 if ( !is_array( $selectOptions ) ) {
2335                         $selectOptions = [ $selectOptions ];
2336                 }
2337
2338                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2339
2340                 if ( is_array( $srcTable ) ) {
2341                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2342                 } else {
2343                         $srcTable = $this->tableName( $srcTable );
2344                 }
2345
2346                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2347                         " SELECT $startOpts " . implode( ',', $varMap ) .
2348                         " FROM $srcTable $useIndex ";
2349
2350                 if ( $conds != '*' ) {
2351                         if ( is_array( $conds ) ) {
2352                                 $conds = $this->makeList( $conds, LIST_AND );
2353                         }
2354                         $sql .= " WHERE $conds";
2355                 }
2356
2357                 $sql .= " $tailOpts";
2358
2359                 return $this->query( $sql, $fname );
2360         }
2361
2362         /**
2363          * Construct a LIMIT query with optional offset. This is used for query
2364          * pages. The SQL should be adjusted so that only the first $limit rows
2365          * are returned. If $offset is provided as well, then the first $offset
2366          * rows should be discarded, and the next $limit rows should be returned.
2367          * If the result of the query is not ordered, then the rows to be returned
2368          * are theoretically arbitrary.
2369          *
2370          * $sql is expected to be a SELECT, if that makes a difference.
2371          *
2372          * The version provided by default works in MySQL and SQLite. It will very
2373          * likely need to be overridden for most other DBMSes.
2374          *
2375          * @param string $sql SQL query we will append the limit too
2376          * @param int $limit The SQL limit
2377          * @param int|bool $offset The SQL offset (default false)
2378          * @throws DBUnexpectedError
2379          * @return string
2380          */
2381         public function limitResult( $sql, $limit, $offset = false ) {
2382                 if ( !is_numeric( $limit ) ) {
2383                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2384                 }
2385
2386                 return "$sql LIMIT "
2387                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2388                         . "{$limit} ";
2389         }
2390
2391         public function unionSupportsOrderAndLimit() {
2392                 return true; // True for almost every DB supported
2393         }
2394
2395         public function unionQueries( $sqls, $all ) {
2396                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2397
2398                 return '(' . implode( $glue, $sqls ) . ')';
2399         }
2400
2401         public function conditional( $cond, $trueVal, $falseVal ) {
2402                 if ( is_array( $cond ) ) {
2403                         $cond = $this->makeList( $cond, LIST_AND );
2404                 }
2405
2406                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2407         }
2408
2409         public function strreplace( $orig, $old, $new ) {
2410                 return "REPLACE({$orig}, {$old}, {$new})";
2411         }
2412
2413         public function getServerUptime() {
2414                 return 0;
2415         }
2416
2417         public function wasDeadlock() {
2418                 return false;
2419         }
2420
2421         public function wasLockTimeout() {
2422                 return false;
2423         }
2424
2425         public function wasErrorReissuable() {
2426                 return false;
2427         }
2428
2429         public function wasReadOnlyError() {
2430                 return false;
2431         }
2432
2433         /**
2434          * Determines if the given query error was a connection drop
2435          * STUB
2436          *
2437          * @param integer|string $errno
2438          * @return bool
2439          */
2440         public function wasConnectionError( $errno ) {
2441                 return false;
2442         }
2443
2444         /**
2445          * Perform a deadlock-prone transaction.
2446          *
2447          * This function invokes a callback function to perform a set of write
2448          * queries. If a deadlock occurs during the processing, the transaction
2449          * will be rolled back and the callback function will be called again.
2450          *
2451          * Avoid using this method outside of Job or Maintenance classes.
2452          *
2453          * Usage:
2454          *   $dbw->deadlockLoop( callback, ... );
2455          *
2456          * Extra arguments are passed through to the specified callback function.
2457          * This method requires that no transactions are already active to avoid
2458          * causing premature commits or exceptions.
2459          *
2460          * Returns whatever the callback function returned on its successful,
2461          * iteration, or false on error, for example if the retry limit was
2462          * reached.
2463          *
2464          * @return mixed
2465          * @throws DBUnexpectedError
2466          * @throws Exception
2467          */
2468         public function deadlockLoop() {
2469                 $args = func_get_args();
2470                 $function = array_shift( $args );
2471                 $tries = self::DEADLOCK_TRIES;
2472
2473                 $this->begin( __METHOD__ );
2474
2475                 $retVal = null;
2476                 /** @var Exception $e */
2477                 $e = null;
2478                 do {
2479                         try {
2480                                 $retVal = call_user_func_array( $function, $args );
2481                                 break;
2482                         } catch ( DBQueryError $e ) {
2483                                 if ( $this->wasDeadlock() ) {
2484                                         // Retry after a randomized delay
2485                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2486                                 } else {
2487                                         // Throw the error back up
2488                                         throw $e;
2489                                 }
2490                         }
2491                 } while ( --$tries > 0 );
2492
2493                 if ( $tries <= 0 ) {
2494                         // Too many deadlocks; give up
2495                         $this->rollback( __METHOD__ );
2496                         throw $e;
2497                 } else {
2498                         $this->commit( __METHOD__ );
2499
2500                         return $retVal;
2501                 }
2502         }
2503
2504         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2505                 # Real waits are implemented in the subclass.
2506                 return 0;
2507         }
2508
2509         public function getSlavePos() {
2510                 # Stub
2511                 return false;
2512         }
2513
2514         public function getMasterPos() {
2515                 # Stub
2516                 return false;
2517         }
2518
2519         public function serverIsReadOnly() {
2520                 return false;
2521         }
2522
2523         final public function onTransactionResolution( callable $callback ) {
2524                 if ( !$this->mTrxLevel ) {
2525                         throw new DBUnexpectedError( $this, "No transaction is active." );
2526                 }
2527                 $this->mTrxEndCallbacks[] = [ $callback, wfGetCaller() ];
2528         }
2529
2530         final public function onTransactionIdle( callable $callback ) {
2531                 $this->mTrxIdleCallbacks[] = [ $callback, wfGetCaller() ];
2532                 if ( !$this->mTrxLevel ) {
2533                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2534                 }
2535         }
2536
2537         final public function onTransactionPreCommitOrIdle( callable $callback ) {
2538                 if ( $this->mTrxLevel ) {
2539                         $this->mTrxPreCommitCallbacks[] = [ $callback, wfGetCaller() ];
2540                 } else {
2541                         // If no transaction is active, then make one for this callback
2542                         $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
2543                         try {
2544                                 call_user_func( $callback );
2545                                 $this->commit( __METHOD__ );
2546                         } catch ( Exception $e ) {
2547                                 $this->rollback( __METHOD__ );
2548                                 throw $e;
2549                         }
2550                 }
2551         }
2552
2553         /**
2554          * Whether to disable running of post-commit callbacks
2555          *
2556          * This method should not be used outside of Database/LoadBalancer
2557          *
2558          * @param bool $suppress
2559          * @since 1.28
2560          */
2561         final public function setPostCommitCallbackSupression( $suppress ) {
2562                 $this->suppressPostCommitCallbacks = $suppress;
2563         }
2564
2565         /**
2566          * Actually run and consume any "on transaction idle/resolution" callbacks.
2567          *
2568          * This method should not be used outside of Database/LoadBalancer
2569          *
2570          * @param integer $trigger IDatabase::TRIGGER_* constant
2571          * @since 1.20
2572          * @throws Exception
2573          */
2574         public function runOnTransactionIdleCallbacks( $trigger ) {
2575                 if ( $this->suppressPostCommitCallbacks ) {
2576                         return;
2577                 }
2578
2579                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2580                 /** @var Exception $e */
2581                 $e = null; // first exception
2582                 do { // callbacks may add callbacks :)
2583                         $callbacks = array_merge(
2584                                 $this->mTrxIdleCallbacks,
2585                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2586                         );
2587                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2588                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2589                         foreach ( $callbacks as $callback ) {
2590                                 try {
2591                                         list( $phpCallback ) = $callback;
2592                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2593                                         call_user_func_array( $phpCallback, [ $trigger ] );
2594                                         if ( $autoTrx ) {
2595                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2596                                         } else {
2597                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2598                                         }
2599                                 } catch ( Exception $ex ) {
2600                                         MWExceptionHandler::logException( $ex );
2601                                         $e = $e ?: $ex;
2602                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2603                                         // their transactions are ended so other callbacks don't fail
2604                                         if ( $this->trxLevel() ) {
2605                                                 $this->rollback( __METHOD__ );
2606                                         }
2607                                 }
2608                         }
2609                 } while ( count( $this->mTrxIdleCallbacks ) );
2610
2611                 if ( $e instanceof Exception ) {
2612                         throw $e; // re-throw any first exception
2613                 }
2614         }
2615
2616         /**
2617          * Actually run and consume any "on transaction pre-commit" callbacks.
2618          *
2619          * This method should not be used outside of Database/LoadBalancer
2620          *
2621          * @since 1.22
2622          * @throws Exception
2623          */
2624         public function runOnTransactionPreCommitCallbacks() {
2625                 $e = null; // first exception
2626                 do { // callbacks may add callbacks :)
2627                         $callbacks = $this->mTrxPreCommitCallbacks;
2628                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2629                         foreach ( $callbacks as $callback ) {
2630                                 try {
2631                                         list( $phpCallback ) = $callback;
2632                                         call_user_func( $phpCallback );
2633                                 } catch ( Exception $ex ) {
2634                                         MWExceptionHandler::logException( $ex );
2635                                         $e = $e ?: $ex;
2636                                 }
2637                         }
2638                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2639
2640                 if ( $e instanceof Exception ) {
2641                         throw $e; // re-throw any first exception
2642                 }
2643         }
2644
2645         final public function startAtomic( $fname = __METHOD__ ) {
2646                 if ( !$this->mTrxLevel ) {
2647                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2648                         $this->mTrxAutomatic = true;
2649                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2650                         // in all changes being in one transaction to keep requests transactional.
2651                         if ( !$this->getFlag( DBO_TRX ) ) {
2652                                 $this->mTrxAutomaticAtomic = true;
2653                         }
2654                 }
2655
2656                 $this->mTrxAtomicLevels[] = $fname;
2657         }
2658
2659         final public function endAtomic( $fname = __METHOD__ ) {
2660                 if ( !$this->mTrxLevel ) {
2661                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2662                 }
2663                 if ( !$this->mTrxAtomicLevels ||
2664                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2665                 ) {
2666                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2667                 }
2668
2669                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2670                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2671                 }
2672         }
2673
2674         final public function doAtomicSection( $fname, callable $callback ) {
2675                 $this->startAtomic( $fname );
2676                 try {
2677                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2678                 } catch ( Exception $e ) {
2679                         $this->rollback( $fname );
2680                         throw $e;
2681                 }
2682                 $this->endAtomic( $fname );
2683
2684                 return $res;
2685         }
2686
2687         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2688                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2689                 if ( $this->mTrxLevel ) {
2690                         if ( $this->mTrxAtomicLevels ) {
2691                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2692                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2693                                 throw new DBUnexpectedError( $this, $msg );
2694                         } elseif ( !$this->mTrxAutomatic ) {
2695                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2696                                 throw new DBUnexpectedError( $this, $msg );
2697                         } else {
2698                                 // @TODO: make this an exception at some point
2699                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2700                                 wfLogDBError( $msg );
2701                                 return; // join the main transaction set
2702                         }
2703                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2704                         // @TODO: make this an exception at some point
2705                         wfLogDBError( "$fname: Implicit transaction expected (DBO_TRX set)." );
2706                         return; // let any writes be in the main transaction
2707                 }
2708
2709                 // Avoid fatals if close() was called
2710                 $this->assertOpen();
2711
2712                 $this->doBegin( $fname );
2713                 $this->mTrxTimestamp = microtime( true );
2714                 $this->mTrxFname = $fname;
2715                 $this->mTrxDoneWrites = false;
2716                 $this->mTrxAutomatic = false;
2717                 $this->mTrxAutomaticAtomic = false;
2718                 $this->mTrxAtomicLevels = [];
2719                 $this->mTrxShortId = wfRandomString( 12 );
2720                 $this->mTrxWriteDuration = 0.0;
2721                 $this->mTrxWriteCallers = [];
2722                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2723                 // Get an estimate of the slave lag before then, treating estimate staleness
2724                 // as lag itself just to be safe
2725                 $status = $this->getApproximateLagStatus();
2726                 $this->mTrxSlaveLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2727         }
2728
2729         /**
2730          * Issues the BEGIN command to the database server.
2731          *
2732          * @see DatabaseBase::begin()
2733          * @param string $fname
2734          */
2735         protected function doBegin( $fname ) {
2736                 $this->query( 'BEGIN', $fname );
2737                 $this->mTrxLevel = 1;
2738         }
2739
2740         final public function commit( $fname = __METHOD__, $flush = '' ) {
2741                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2742                         // There are still atomic sections open. This cannot be ignored
2743                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2744                         throw new DBUnexpectedError(
2745                                 $this,
2746                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2747                         );
2748                 }
2749
2750                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2751                         if ( !$this->mTrxLevel ) {
2752                                 return; // nothing to do
2753                         } elseif ( !$this->mTrxAutomatic ) {
2754                                 throw new DBUnexpectedError(
2755                                         $this,
2756                                         "$fname: Flushing an explicit transaction, getting out of sync."
2757                                 );
2758                         }
2759                 } else {
2760                         if ( !$this->mTrxLevel ) {
2761                                 wfWarn( "$fname: No transaction to commit, something got out of sync." );
2762                                 return; // nothing to do
2763                         } elseif ( $this->mTrxAutomatic ) {
2764                                 // @TODO: make this an exception at some point
2765                                 wfLogDBError( "$fname: Explicit commit of implicit transaction." );
2766                                 return; // wait for the main transaction set commit round
2767                         }
2768                 }
2769
2770                 // Avoid fatals if close() was called
2771                 $this->assertOpen();
2772
2773                 $this->runOnTransactionPreCommitCallbacks();
2774                 $writeTime = $this->pendingWriteQueryDuration();
2775                 $this->doCommit( $fname );
2776                 if ( $this->mTrxDoneWrites ) {
2777                         $this->mDoneWrites = microtime( true );
2778                         $this->getTransactionProfiler()->transactionWritingOut(
2779                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2780                 }
2781
2782                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
2783         }
2784
2785         /**
2786          * Issues the COMMIT command to the database server.
2787          *
2788          * @see DatabaseBase::commit()
2789          * @param string $fname
2790          */
2791         protected function doCommit( $fname ) {
2792                 if ( $this->mTrxLevel ) {
2793                         $this->query( 'COMMIT', $fname );
2794                         $this->mTrxLevel = 0;
2795                 }
2796         }
2797
2798         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2799                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2800                         if ( !$this->mTrxLevel ) {
2801                                 return; // nothing to do
2802                         }
2803                 } else {
2804                         if ( !$this->mTrxLevel ) {
2805                                 wfWarn( "$fname: No transaction to rollback, something got out of sync." );
2806                                 return; // nothing to do
2807                         } elseif ( $this->getFlag( DBO_TRX ) ) {
2808                                 throw new DBUnexpectedError(
2809                                         $this,
2810                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
2811                                 );
2812                         }
2813                 }
2814
2815                 // Avoid fatals if close() was called
2816                 $this->assertOpen();
2817
2818                 $this->doRollback( $fname );
2819                 $this->mTrxAtomicLevels = [];
2820                 if ( $this->mTrxDoneWrites ) {
2821                         $this->getTransactionProfiler()->transactionWritingOut(
2822                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2823                 }
2824
2825                 $this->mTrxIdleCallbacks = []; // clear
2826                 $this->mTrxPreCommitCallbacks = []; // clear
2827                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
2828         }
2829
2830         /**
2831          * Issues the ROLLBACK command to the database server.
2832          *
2833          * @see DatabaseBase::rollback()
2834          * @param string $fname
2835          */
2836         protected function doRollback( $fname ) {
2837                 if ( $this->mTrxLevel ) {
2838                         # Disconnects cause rollback anyway, so ignore those errors
2839                         $ignoreErrors = true;
2840                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
2841                         $this->mTrxLevel = 0;
2842                 }
2843         }
2844
2845         public function explicitTrxActive() {
2846                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
2847         }
2848
2849         /**
2850          * Creates a new table with structure copied from existing table
2851          * Note that unlike most database abstraction functions, this function does not
2852          * automatically append database prefix, because it works at a lower
2853          * abstraction level.
2854          * The table names passed to this function shall not be quoted (this
2855          * function calls addIdentifierQuotes when needed).
2856          *
2857          * @param string $oldName Name of table whose structure should be copied
2858          * @param string $newName Name of table to be created
2859          * @param bool $temporary Whether the new table should be temporary
2860          * @param string $fname Calling function name
2861          * @throws MWException
2862          * @return bool True if operation was successful
2863          */
2864         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2865                 $fname = __METHOD__
2866         ) {
2867                 throw new MWException(
2868                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2869         }
2870
2871         function listTables( $prefix = null, $fname = __METHOD__ ) {
2872                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2873         }
2874
2875         /**
2876          * Reset the views process cache set by listViews()
2877          * @since 1.22
2878          */
2879         final public function clearViewsCache() {
2880                 $this->allViews = null;
2881         }
2882
2883         /**
2884          * Lists all the VIEWs in the database
2885          *
2886          * For caching purposes the list of all views should be stored in
2887          * $this->allViews. The process cache can be cleared with clearViewsCache()
2888          *
2889          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2890          * @param string $fname Name of calling function
2891          * @throws MWException
2892          * @return array
2893          * @since 1.22
2894          */
2895         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2896                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
2897         }
2898
2899         /**
2900          * Differentiates between a TABLE and a VIEW
2901          *
2902          * @param string $name Name of the database-structure to test.
2903          * @throws MWException
2904          * @return bool
2905          * @since 1.22
2906          */
2907         public function isView( $name ) {
2908                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
2909         }
2910
2911         public function timestamp( $ts = 0 ) {
2912                 return wfTimestamp( TS_MW, $ts );
2913         }
2914
2915         public function timestampOrNull( $ts = null ) {
2916                 if ( is_null( $ts ) ) {
2917                         return null;
2918                 } else {
2919                         return $this->timestamp( $ts );
2920                 }
2921         }
2922
2923         /**
2924          * Take the result from a query, and wrap it in a ResultWrapper if
2925          * necessary. Boolean values are passed through as is, to indicate success
2926          * of write queries or failure.
2927          *
2928          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2929          * resource, and it was necessary to call this function to convert it to
2930          * a wrapper. Nowadays, raw database objects are never exposed to external
2931          * callers, so this is unnecessary in external code.
2932          *
2933          * @param bool|ResultWrapper|resource|object $result
2934          * @return bool|ResultWrapper
2935          */
2936         protected function resultObject( $result ) {
2937                 if ( !$result ) {
2938                         return false;
2939                 } elseif ( $result instanceof ResultWrapper ) {
2940                         return $result;
2941                 } elseif ( $result === true ) {
2942                         // Successful write query
2943                         return $result;
2944                 } else {
2945                         return new ResultWrapper( $this, $result );
2946                 }
2947         }
2948
2949         public function ping() {
2950                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
2951                         return true;
2952                 }
2953                 try {
2954                         // This will reconnect if possible, or error out if not
2955                         $this->query( "SELECT 1 AS ping", __METHOD__ );
2956                         return true;
2957                 } catch ( DBError $e ) {
2958                         return false;
2959                 }
2960         }
2961
2962         /**
2963          * @return bool
2964          */
2965         protected function reconnect() {
2966                 $this->closeConnection();
2967                 $this->mOpened = false;
2968                 $this->mConn = false;
2969                 try {
2970                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
2971                         $this->lastPing = microtime( true );
2972                         $ok = true;
2973                 } catch ( DBConnectionError $e ) {
2974                         $ok = false;
2975                 }
2976
2977                 return $ok;
2978         }
2979
2980         public function getSessionLagStatus() {
2981                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2982         }
2983
2984         /**
2985          * Get the slave lag when the current transaction started
2986          *
2987          * This is useful when transactions might use snapshot isolation
2988          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2989          * is this lag plus transaction duration. If they don't, it is still
2990          * safe to be pessimistic. This returns null if there is no transaction.
2991          *
2992          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2993          * @since 1.27
2994          */
2995         public function getTransactionLagStatus() {
2996                 return $this->mTrxLevel
2997                         ? [ 'lag' => $this->mTrxSlaveLag, 'since' => $this->trxTimestamp() ]
2998                         : null;
2999         }
3000
3001         /**
3002          * Get a slave lag estimate for this server
3003          *
3004          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3005          * @since 1.27
3006          */
3007         public function getApproximateLagStatus() {
3008                 return [
3009                         'lag'   => $this->getLBInfo( 'slave' ) ? $this->getLag() : 0,
3010                         'since' => microtime( true )
3011                 ];
3012         }
3013
3014         /**
3015          * Merge the result of getSessionLagStatus() for several DBs
3016          * using the most pessimistic values to estimate the lag of
3017          * any data derived from them in combination
3018          *
3019          * This is information is useful for caching modules
3020          *
3021          * @see WANObjectCache::set()
3022          * @see WANObjectCache::getWithSetCallback()
3023          *
3024          * @param IDatabase $db1
3025          * @param IDatabase ...
3026          * @return array Map of values:
3027          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3028          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3029          *   - pending: whether any of the DBs have uncommitted changes
3030          * @since 1.27
3031          */
3032         public static function getCacheSetOptions( IDatabase $db1 ) {
3033                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3034                 foreach ( func_get_args() as $db ) {
3035                         /** @var IDatabase $db */
3036                         $status = $db->getSessionLagStatus();
3037                         if ( $status['lag'] === false ) {
3038                                 $res['lag'] = false;
3039                         } elseif ( $res['lag'] !== false ) {
3040                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3041                         }
3042                         $res['since'] = min( $res['since'], $status['since'] );
3043                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3044                 }
3045
3046                 return $res;
3047         }
3048
3049         public function getLag() {
3050                 return 0;
3051         }
3052
3053         function maxListLen() {
3054                 return 0;
3055         }
3056
3057         public function encodeBlob( $b ) {
3058                 return $b;
3059         }
3060
3061         public function decodeBlob( $b ) {
3062                 if ( $b instanceof Blob ) {
3063                         $b = $b->fetch();
3064                 }
3065                 return $b;
3066         }
3067
3068         public function setSessionOptions( array $options ) {
3069         }
3070
3071         /**
3072          * Read and execute SQL commands from a file.
3073          *
3074          * Returns true on success, error string or exception on failure (depending
3075          * on object's error ignore settings).
3076          *
3077          * @param string $filename File name to open
3078          * @param bool|callable $lineCallback Optional function called before reading each line
3079          * @param bool|callable $resultCallback Optional function called for each MySQL result
3080          * @param bool|string $fname Calling function name or false if name should be
3081          *   generated dynamically using $filename
3082          * @param bool|callable $inputCallback Optional function called for each
3083          *   complete line sent
3084          * @throws Exception|MWException
3085          * @return bool|string
3086          */
3087         public function sourceFile(
3088                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3089         ) {
3090                 MediaWiki\suppressWarnings();
3091                 $fp = fopen( $filename, 'r' );
3092                 MediaWiki\restoreWarnings();
3093
3094                 if ( false === $fp ) {
3095                         throw new MWException( "Could not open \"{$filename}\".\n" );
3096                 }
3097
3098                 if ( !$fname ) {
3099                         $fname = __METHOD__ . "( $filename )";
3100                 }
3101
3102                 try {
3103                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3104                 } catch ( Exception $e ) {
3105                         fclose( $fp );
3106                         throw $e;
3107                 }
3108
3109                 fclose( $fp );
3110
3111                 return $error;
3112         }
3113
3114         /**
3115          * Get the full path of a patch file. Originally based on archive()
3116          * from updaters.inc. Keep in mind this always returns a patch, as
3117          * it fails back to MySQL if no DB-specific patch can be found
3118          *
3119          * @param string $patch The name of the patch, like patch-something.sql
3120          * @return string Full path to patch file
3121          */
3122         public function patchPath( $patch ) {
3123                 global $IP;
3124
3125                 $dbType = $this->getType();
3126                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3127                         return "$IP/maintenance/$dbType/archives/$patch";
3128                 } else {
3129                         return "$IP/maintenance/archives/$patch";
3130                 }
3131         }
3132
3133         public function setSchemaVars( $vars ) {
3134                 $this->mSchemaVars = $vars;
3135         }
3136
3137         /**
3138          * Read and execute commands from an open file handle.
3139          *
3140          * Returns true on success, error string or exception on failure (depending
3141          * on object's error ignore settings).
3142          *
3143          * @param resource $fp File handle
3144          * @param bool|callable $lineCallback Optional function called before reading each query
3145          * @param bool|callable $resultCallback Optional function called for each MySQL result
3146          * @param string $fname Calling function name
3147          * @param bool|callable $inputCallback Optional function called for each complete query sent
3148          * @return bool|string
3149          */
3150         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3151                 $fname = __METHOD__, $inputCallback = false
3152         ) {
3153                 $cmd = '';
3154
3155                 while ( !feof( $fp ) ) {
3156                         if ( $lineCallback ) {
3157                                 call_user_func( $lineCallback );
3158                         }
3159
3160                         $line = trim( fgets( $fp ) );
3161
3162                         if ( $line == '' ) {
3163                                 continue;
3164                         }
3165
3166                         if ( '-' == $line[0] && '-' == $line[1] ) {
3167                                 continue;
3168                         }
3169
3170                         if ( $cmd != '' ) {
3171                                 $cmd .= ' ';
3172                         }
3173
3174                         $done = $this->streamStatementEnd( $cmd, $line );
3175
3176                         $cmd .= "$line\n";
3177
3178                         if ( $done || feof( $fp ) ) {
3179                                 $cmd = $this->replaceVars( $cmd );
3180
3181                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3182                                         $res = $this->query( $cmd, $fname );
3183
3184                                         if ( $resultCallback ) {
3185                                                 call_user_func( $resultCallback, $res, $this );
3186                                         }
3187
3188                                         if ( false === $res ) {
3189                                                 $err = $this->lastError();
3190
3191                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3192                                         }
3193                                 }
3194                                 $cmd = '';
3195                         }
3196                 }
3197
3198                 return true;
3199         }
3200
3201         /**
3202          * Called by sourceStream() to check if we've reached a statement end
3203          *
3204          * @param string $sql SQL assembled so far
3205          * @param string $newLine New line about to be added to $sql
3206          * @return bool Whether $newLine contains end of the statement
3207          */
3208         public function streamStatementEnd( &$sql, &$newLine ) {
3209                 if ( $this->delimiter ) {
3210                         $prev = $newLine;
3211                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3212                         if ( $newLine != $prev ) {
3213                                 return true;
3214                         }
3215                 }
3216
3217                 return false;
3218         }
3219
3220         /**
3221          * Database independent variable replacement. Replaces a set of variables
3222          * in an SQL statement with their contents as given by $this->getSchemaVars().
3223          *
3224          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3225          *
3226          * - '{$var}' should be used for text and is passed through the database's
3227          *   addQuotes method.
3228          * - `{$var}` should be used for identifiers (e.g. table and database names).
3229          *   It is passed through the database's addIdentifierQuotes method which
3230          *   can be overridden if the database uses something other than backticks.
3231          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3232          *   database's tableName method.
3233          * - / *i* / passes the name that follows through the database's indexName method.
3234          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3235          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3236          *
3237          * @param string $ins SQL statement to replace variables in
3238          * @return string The new SQL statement with variables replaced
3239          */
3240         protected function replaceVars( $ins ) {
3241                 $vars = $this->getSchemaVars();
3242                 return preg_replace_callback(
3243                         '!
3244                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3245                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3246                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3247                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3248                         !x',
3249                         function ( $m ) use ( $vars ) {
3250                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3251                                 // check for both nonexistent keys *and* the empty string.
3252                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3253                                         if ( $m[1] === 'i' ) {
3254                                                 return $this->indexName( $m[2] );
3255                                         } else {
3256                                                 return $this->tableName( $m[2] );
3257                                         }
3258                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3259                                         return $this->addQuotes( $vars[$m[3]] );
3260                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3261                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3262                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3263                                         return $vars[$m[5]];
3264                                 } else {
3265                                         return $m[0];
3266                                 }
3267                         },
3268                         $ins
3269                 );
3270         }
3271
3272         /**
3273          * Get schema variables. If none have been set via setSchemaVars(), then
3274          * use some defaults from the current object.
3275          *
3276          * @return array
3277          */
3278         protected function getSchemaVars() {
3279                 if ( $this->mSchemaVars ) {
3280                         return $this->mSchemaVars;
3281                 } else {
3282                         return $this->getDefaultSchemaVars();
3283                 }
3284         }
3285
3286         /**
3287          * Get schema variables to use if none have been set via setSchemaVars().
3288          *
3289          * Override this in derived classes to provide variables for tables.sql
3290          * and SQL patch files.
3291          *
3292          * @return array
3293          */
3294         protected function getDefaultSchemaVars() {
3295                 return [];
3296         }
3297
3298         public function lockIsFree( $lockName, $method ) {
3299                 return true;
3300         }
3301
3302         public function lock( $lockName, $method, $timeout = 5 ) {
3303                 $this->mNamedLocksHeld[$lockName] = 1;
3304
3305                 return true;
3306         }
3307
3308         public function unlock( $lockName, $method ) {
3309                 unset( $this->mNamedLocksHeld[$lockName] );
3310
3311                 return true;
3312         }
3313
3314         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3315                 if ( $this->writesOrCallbacksPending() ) {
3316                         // This only flushes transactions to clear snapshots, not to write data
3317                         throw new DBUnexpectedError(
3318                                 $this,
3319                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3320                         );
3321                 }
3322
3323                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3324                         return null;
3325                 }
3326
3327                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3328                         if ( $this->trxLevel() ) {
3329                                 // There is a good chance an exception was thrown, causing any early return
3330                                 // from the caller. Let any error handler get a chance to issue rollback().
3331                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3332                                 $this->onTransactionResolution( function () use ( $lockKey, $fname ) {
3333                                         $this->unlock( $lockKey, $fname );
3334                                 } );
3335                         } else {
3336                                 $this->unlock( $lockKey, $fname );
3337                         }
3338                 } );
3339
3340                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
3341
3342                 return $unlocker;
3343         }
3344
3345         public function namedLocksEnqueue() {
3346                 return false;
3347         }
3348
3349         /**
3350          * Lock specific tables
3351          *
3352          * @param array $read Array of tables to lock for read access
3353          * @param array $write Array of tables to lock for write access
3354          * @param string $method Name of caller
3355          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3356          * @return bool
3357          */
3358         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3359                 return true;
3360         }
3361
3362         /**
3363          * Unlock specific tables
3364          *
3365          * @param string $method The caller
3366          * @return bool
3367          */
3368         public function unlockTables( $method ) {
3369                 return true;
3370         }
3371
3372         /**
3373          * Delete a table
3374          * @param string $tableName
3375          * @param string $fName
3376          * @return bool|ResultWrapper
3377          * @since 1.18
3378          */
3379         public function dropTable( $tableName, $fName = __METHOD__ ) {
3380                 if ( !$this->tableExists( $tableName, $fName ) ) {
3381                         return false;
3382                 }
3383                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3384                 if ( $this->cascadingDeletes() ) {
3385                         $sql .= " CASCADE";
3386                 }
3387
3388                 return $this->query( $sql, $fName );
3389         }
3390
3391         /**
3392          * Get search engine class. All subclasses of this need to implement this
3393          * if they wish to use searching.
3394          *
3395          * @return string
3396          */
3397         public function getSearchEngine() {
3398                 return 'SearchEngineDummy';
3399         }
3400
3401         public function getInfinity() {
3402                 return 'infinity';
3403         }
3404
3405         public function encodeExpiry( $expiry ) {
3406                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3407                         ? $this->getInfinity()
3408                         : $this->timestamp( $expiry );
3409         }
3410
3411         public function decodeExpiry( $expiry, $format = TS_MW ) {
3412                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3413                         ? 'infinity'
3414                         : wfTimestamp( $format, $expiry );
3415         }
3416
3417         public function setBigSelects( $value = true ) {
3418                 // no-op
3419         }
3420
3421         public function isReadOnly() {
3422                 return ( $this->getReadOnlyReason() !== false );
3423         }
3424
3425         /**
3426          * @return string|bool Reason this DB is read-only or false if it is not
3427          */
3428         protected function getReadOnlyReason() {
3429                 $reason = $this->getLBInfo( 'readOnlyReason' );
3430
3431                 return is_string( $reason ) ? $reason : false;
3432         }
3433
3434         /**
3435          * @since 1.19
3436          * @return string
3437          */
3438         public function __toString() {
3439                 return (string)$this->mConn;
3440         }
3441
3442         /**
3443          * Run a few simple sanity checks
3444          */
3445         public function __destruct() {
3446                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3447                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3448                 }
3449                 $danglingCallbacks = array_merge(
3450                         $this->mTrxIdleCallbacks,
3451                         $this->mTrxPreCommitCallbacks,
3452                         $this->mTrxEndCallbacks
3453                 );
3454                 if ( $danglingCallbacks ) {
3455                         $callers = [];
3456                         foreach ( $danglingCallbacks as $callbackInfo ) {
3457                                 $callers[] = $callbackInfo[1];
3458                         }
3459                         $callers = implode( ', ', $callers );
3460                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3461                 }
3462         }
3463 }
3464
3465 /**
3466  * @since 1.27
3467  */
3468 abstract class Database extends DatabaseBase {
3469         // B/C until nothing type hints for DatabaseBase
3470         // @TODO: finish renaming DatabaseBase => Database
3471 }