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         const PING_QUERY = 'SELECT 1 AS ping';
  43
  44         const TINY_WRITE_SEC = .010;
  45         const SLOW_WRITE_SEC = .500;
  46         const SMALL_WRITE_ROWS = 100;
  47
  48         /** @var string SQL query */
  49         protected $mLastQuery = '';
  50         /** @var bool */
  51         protected $mDoneWrites = false;
  52         /** @var string|bool */
  53         protected $mPHPError = false;
  54         /** @var string */
  55         protected $mServer;
  56         /** @var string */
  57         protected $mUser;
  58         /** @var string */
  59         protected $mPassword;
  60         /** @var string */
  61         protected $mDBname;
  62         /** @var bool */
  63         protected $cliMode;
  64
  65         /** @var BagOStuff APC cache */
  66         protected $srvCache;
  67
  68         /** @var resource Database connection */
  69         protected $mConn = null;
  70         /** @var bool */
  71         protected $mOpened = false;
  72
  73         /** @var array[] List of (callable, method name) */
  74         protected $mTrxIdleCallbacks = [];
  75         /** @var array[] List of (callable, method name) */
  76         protected $mTrxPreCommitCallbacks = [];
  77         /** @var array[] List of (callable, method name) */
  78         protected $mTrxEndCallbacks = [];
  79         /** @var array[] Map of (name => (callable, method name)) */
  80         protected $mTrxRecurringCallbacks = [];
  81         /** @var bool Whether to suppress triggering of transaction end callbacks */
  82         protected $mTrxEndCallbacksSuppressed = false;
  83
  84         /** @var string */
  85         protected $mTablePrefix;
  86         /** @var string */
  87         protected $mSchema;
  88         /** @var integer */
  89         protected $mFlags;
  90         /** @var bool */
  91         protected $mForeign;
  92         /** @var array */
  93         protected $mLBInfo = [];
  94         /** @var bool|null */
  95         protected $mDefaultBigSelects = null;
  96         /** @var array|bool */
  97         protected $mSchemaVars = false;
  98         /** @var array */
  99         protected $mSessionVars = [];
 100         /** @var array|null */
 101         protected $preparedArgs;
 102         /** @var string|bool|null Stashed value of html_errors INI setting */
 103         protected $htmlErrors;
 104         /** @var string */
 105         protected $delimiter = ';';
 106
 107         /**
 108          * Either 1 if a transaction is active or 0 otherwise.
 109          * The other Trx fields may not be meaningfull if this is 0.
 110          *
 111          * @var int
 112          */
 113         protected $mTrxLevel = 0;
 114         /**
 115          * Either a short hexidecimal string if a transaction is active or ""
 116          *
 117          * @var string
 118          * @see DatabaseBase::mTrxLevel
 119          */
 120         protected $mTrxShortId = '';
 121         /**
 122          * The UNIX time that the transaction started. Callers can assume that if
 123          * snapshot isolation is used, then the data is *at least* up to date to that
 124          * point (possibly more up-to-date since the first SELECT defines the snapshot).
 125          *
 126          * @var float|null
 127          * @see DatabaseBase::mTrxLevel
 128          */
 129         private $mTrxTimestamp = null;
 130         /** @var float Lag estimate at the time of BEGIN */
 131         private $mTrxReplicaLag = null;
 132         /**
 133          * Remembers the function name given for starting the most recent transaction via begin().
 134          * Used to provide additional context for error reporting.
 135          *
 136          * @var string
 137          * @see DatabaseBase::mTrxLevel
 138          */
 139         private $mTrxFname = null;
 140         /**
 141          * Record if possible write queries were done in the last transaction started
 142          *
 143          * @var bool
 144          * @see DatabaseBase::mTrxLevel
 145          */
 146         private $mTrxDoneWrites = false;
 147         /**
 148          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 149          *
 150          * @var bool
 151          * @see DatabaseBase::mTrxLevel
 152          */
 153         private $mTrxAutomatic = false;
 154         /**
 155          * Array of levels of atomicity within transactions
 156          *
 157          * @var array
 158          */
 159         private $mTrxAtomicLevels = [];
 160         /**
 161          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 162          *
 163          * @var bool
 164          */
 165         private $mTrxAutomaticAtomic = false;
 166         /**
 167          * Track the write query callers of the current transaction
 168          *
 169          * @var string[]
 170          */
 171         private $mTrxWriteCallers = [];
 172         /**
 173          * @var float Seconds spent in write queries for the current transaction
 174          */
 175         private $mTrxWriteDuration = 0.0;
 176         /**
 177          * @var integer Number of write queries for the current transaction
 178          */
 179         private $mTrxWriteQueryCount = 0;
 180         /**
 181          * @var float Like mTrxWriteQueryCount but excludes lock-bound, easy to replicate, queries
 182          */
 183         private $mTrxWriteAdjDuration = 0.0;
 184         /**
 185          * @var integer Number of write queries counted in mTrxWriteAdjDuration
 186          */
 187         private $mTrxWriteAdjQueryCount = 0;
 188         /**
 189          * @var float RTT time estimate
 190          */
 191         private $mRTTEstimate = 0.0;
 192
 193         /** @var array Map of (name => 1) for locks obtained via lock() */
 194         private $mNamedLocksHeld = [];
 195
 196         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 197         private $lazyMasterHandle;
 198
 199         /**
 200          * @since 1.21
 201          * @var resource File handle for upgrade
 202          */
 203         protected $fileHandle = null;
 204
 205         /**
 206          * @since 1.22
 207          * @var string[] Process cache of VIEWs names in the database
 208          */
 209         protected $allViews = null;
 210
 211         /** @var float UNIX timestamp */
 212         protected $lastPing = 0.0;
 213
 214         /** @var int[] Prior mFlags values */
 215         private $priorFlags = [];
 216
 217         /** @var Profiler */
 218         protected $profiler;
 219         /** @var TransactionProfiler */
 220         protected $trxProfiler;
 221
 222         public function getServerInfo() {
 223                 return $this->getServerVersion();
 224         }
 225
 226         /**
 227          * @return string Command delimiter used by this database engine
 228          */
 229         public function getDelimiter() {
 230                 return $this->delimiter;
 231         }
 232
 233         /**
 234          * Boolean, controls output of large amounts of debug information.
 235          * @param bool|null $debug
 236          *   - true to enable debugging
 237          *   - false to disable debugging
 238          *   - omitted or null to do nothing
 239          *
 240          * @return bool|null Previous value of the flag
 241          */
 242         public function debug( $debug = null ) {
 243                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 244         }
 245
 246         public function bufferResults( $buffer = null ) {
 247                 if ( is_null( $buffer ) ) {
 248                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 249                 } else {
 250                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 251                 }
 252         }
 253
 254         /**
 255          * Turns on (false) or off (true) the automatic generation and sending
 256          * of a "we're sorry, but there has been a database error" page on
 257          * database errors. Default is on (false). When turned off, the
 258          * code should use lastErrno() and lastError() to handle the
 259          * situation as appropriate.
 260          *
 261          * Do not use this function outside of the Database classes.
 262          *
 263          * @param null|bool $ignoreErrors
 264          * @return bool The previous value of the flag.
 265          */
 266         protected function ignoreErrors( $ignoreErrors = null ) {
 267                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 268         }
 269
 270         public function trxLevel() {
 271                 return $this->mTrxLevel;
 272         }
 273
 274         public function trxTimestamp() {
 275                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 276         }
 277
 278         public function tablePrefix( $prefix = null ) {
 279                 return wfSetVar( $this->mTablePrefix, $prefix );
 280         }
 281
 282         public function dbSchema( $schema = null ) {
 283                 return wfSetVar( $this->mSchema, $schema );
 284         }
 285
 286         /**
 287          * Set the filehandle to copy write statements to.
 288          *
 289          * @param resource $fh File handle
 290          */
 291         public function setFileHandle( $fh ) {
 292                 $this->fileHandle = $fh;
 293         }
 294
 295         public function getLBInfo( $name = null ) {
 296                 if ( is_null( $name ) ) {
 297                         return $this->mLBInfo;
 298                 } else {
 299                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 300                                 return $this->mLBInfo[$name];
 301                         } else {
 302                                 return null;
 303                         }
 304                 }
 305         }
 306
 307         public function setLBInfo( $name, $value = null ) {
 308                 if ( is_null( $value ) ) {
 309                         $this->mLBInfo = $name;
 310                 } else {
 311                         $this->mLBInfo[$name] = $value;
 312                 }
 313         }
 314
 315         /**
 316          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 317          *
 318          * @param IDatabase $conn
 319          * @since 1.27
 320          */
 321         public function setLazyMasterHandle( IDatabase $conn ) {
 322                 $this->lazyMasterHandle = $conn;
 323         }
 324
 325         /**
 326          * @return IDatabase|null
 327          * @see setLazyMasterHandle()
 328          * @since 1.27
 329          */
 330         public function getLazyMasterHandle() {
 331                 return $this->lazyMasterHandle;
 332         }
 333
 334         /**
 335          * @param TransactionProfiler $profiler
 336          * @since 1.27
 337          */
 338         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 339                 $this->trxProfiler = $profiler;
 340         }
 341
 342         /**
 343          * Returns true if this database supports (and uses) cascading deletes
 344          *
 345          * @return bool
 346          */
 347         public function cascadingDeletes() {
 348                 return false;
 349         }
 350
 351         /**
 352          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 353          *
 354          * @return bool
 355          */
 356         public function cleanupTriggers() {
 357                 return false;
 358         }
 359
 360         /**
 361          * Returns true if this database is strict about what can be put into an IP field.
 362          * Specifically, it uses a NULL value instead of an empty string.
 363          *
 364          * @return bool
 365          */
 366         public function strictIPs() {
 367                 return false;
 368         }
 369
 370         /**
 371          * Returns true if this database uses timestamps rather than integers
 372          *
 373          * @return bool
 374          */
 375         public function realTimestamps() {
 376                 return false;
 377         }
 378
 379         public function implicitGroupby() {
 380                 return true;
 381         }
 382
 383         public function implicitOrderby() {
 384                 return true;
 385         }
 386
 387         /**
 388          * Returns true if this database can do a native search on IP columns
 389          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 390          *
 391          * @return bool
 392          */
 393         public function searchableIPs() {
 394                 return false;
 395         }
 396
 397         /**
 398          * Returns true if this database can use functional indexes
 399          *
 400          * @return bool
 401          */
 402         public function functionalIndexes() {
 403                 return false;
 404         }
 405
 406         public function lastQuery() {
 407                 return $this->mLastQuery;
 408         }
 409
 410         public function doneWrites() {
 411                 return (bool)$this->mDoneWrites;
 412         }
 413
 414         public function lastDoneWrites() {
 415                 return $this->mDoneWrites ?: false;
 416         }
 417
 418         public function writesPending() {
 419                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 420         }
 421
 422         public function writesOrCallbacksPending() {
 423                 return $this->mTrxLevel && (
 424                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 425                 );
 426         }
 427
 428         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL ) {
 429                 if ( !$this->mTrxLevel ) {
 430                         return false;
 431                 } elseif ( !$this->mTrxDoneWrites ) {
 432                         return 0.0;
 433                 }
 434
 435                 switch ( $type ) {
 436                         case self::ESTIMATE_DB_APPLY:
 437                                 $this->ping( $rtt );
 438                                 $rttAdjTotal = $this->mTrxWriteAdjQueryCount * $rtt;
 439                                 $applyTime = max( $this->mTrxWriteAdjDuration - $rttAdjTotal, 0 );
 440                                 // For omitted queries, make them count as something at least
 441                                 $omitted = $this->mTrxWriteQueryCount - $this->mTrxWriteAdjQueryCount;
 442                                 $applyTime += self::TINY_WRITE_SEC * $omitted;
 443
 444                                 return $applyTime;
 445                         default: // everything
 446                                 return $this->mTrxWriteDuration;
 447                 }
 448         }
 449
 450         public function pendingWriteCallers() {
 451                 return $this->mTrxLevel ? $this->mTrxWriteCallers : [];
 452         }
 453
 454         public function isOpen() {
 455                 return $this->mOpened;
 456         }
 457
 458         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 459                 if ( $remember === self::REMEMBER_PRIOR ) {
 460                         array_push( $this->priorFlags, $this->mFlags );
 461                 }
 462                 $this->mFlags |= $flag;
 463         }
 464
 465         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING ) {
 466                 if ( $remember === self::REMEMBER_PRIOR ) {
 467                         array_push( $this->priorFlags, $this->mFlags );
 468                 }
 469                 $this->mFlags &= ~$flag;
 470         }
 471
 472         public function restoreFlags( $state = self::RESTORE_PRIOR ) {
 473                 if ( !$this->priorFlags ) {
 474                         return;
 475                 }
 476
 477                 if ( $state === self::RESTORE_INITIAL ) {
 478                         $this->mFlags = reset( $this->priorFlags );
 479                         $this->priorFlags = [];
 480                 } else {
 481                         $this->mFlags = array_pop( $this->priorFlags );
 482                 }
 483         }
 484
 485         public function getFlag( $flag ) {
 486                 return !!( $this->mFlags & $flag );
 487         }
 488
 489         public function getProperty( $name ) {
 490                 return $this->$name;
 491         }
 492
 493         public function getWikiID() {
 494                 if ( $this->mTablePrefix ) {
 495                         return "{$this->mDBname}-{$this->mTablePrefix}";
 496                 } else {
 497                         return $this->mDBname;
 498                 }
 499         }
 500
 501         /**
 502          * Return a path to the DBMS-specific SQL file if it exists,
 503          * otherwise default SQL file
 504          *
 505          * @param string $filename
 506          * @return string
 507          */
 508         private function getSqlFilePath( $filename ) {
 509                 global $IP;
 510                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 511                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 512                         return $dbmsSpecificFilePath;
 513                 } else {
 514                         return "$IP/maintenance/$filename";
 515                 }
 516         }
 517
 518         /**
 519          * Return a path to the DBMS-specific schema file,
 520          * otherwise default to tables.sql
 521          *
 522          * @return string
 523          */
 524         public function getSchemaPath() {
 525                 return $this->getSqlFilePath( 'tables.sql' );
 526         }
 527
 528         /**
 529          * Return a path to the DBMS-specific update key file,
 530          * otherwise default to update-keys.sql
 531          *
 532          * @return string
 533          */
 534         public function getUpdateKeysPath() {
 535                 return $this->getSqlFilePath( 'update-keys.sql' );
 536         }
 537
 538         /**
 539          * Get information about an index into an object
 540          * @param string $table Table name
 541          * @param string $index Index name
 542          * @param string $fname Calling function name
 543          * @return mixed Database-specific index description class or false if the index does not exist
 544          */
 545         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 546
 547         /**
 548          * Wrapper for addslashes()
 549          *
 550          * @param string $s String to be slashed.
 551          * @return string Slashed string.
 552          */
 553         abstract function strencode( $s );
 554
 555         /**
 556          * Constructor.
 557          *
 558          * FIXME: It is possible to construct a Database object with no associated
 559          * connection object, by specifying no parameters to __construct(). This
 560          * feature is deprecated and should be removed.
 561          *
 562          * DatabaseBase subclasses should not be constructed directly in external
 563          * code. DatabaseBase::factory() should be used instead.
 564          *
 565          * @param array $params Parameters passed from DatabaseBase::factory()
 566          */
 567         function __construct( array $params ) {
 568                 global $wgDBprefix, $wgDBmwschema;
 569
 570                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 571
 572                 $server = $params['host'];
 573                 $user = $params['user'];
 574                 $password = $params['password'];
 575                 $dbName = $params['dbname'];
 576                 $flags = $params['flags'];
 577                 $tablePrefix = $params['tablePrefix'];
 578                 $schema = $params['schema'];
 579                 $foreign = $params['foreign'];
 580
 581                 $this->cliMode = isset( $params['cliMode'] )
 582                         ? $params['cliMode']
 583                         : ( PHP_SAPI === 'cli' );
 584
 585                 $this->mFlags = $flags;
 586                 if ( $this->mFlags & DBO_DEFAULT ) {
 587                         if ( $this->cliMode ) {
 588                                 $this->mFlags &= ~DBO_TRX;
 589                         } else {
 590                                 $this->mFlags |= DBO_TRX;
 591                         }
 592                 }
 593
 594                 $this->mSessionVars = $params['variables'];
 595
 596                 /** Get the default table prefix*/
 597                 if ( $tablePrefix === 'get from global' ) {
 598                         $this->mTablePrefix = $wgDBprefix;
 599                 } else {
 600                         $this->mTablePrefix = $tablePrefix;
 601                 }
 602
 603                 /** Get the database schema*/
 604                 if ( $schema === 'get from global' ) {
 605                         $this->mSchema = $wgDBmwschema;
 606                 } else {
 607                         $this->mSchema = $schema;
 608                 }
 609
 610                 $this->mForeign = $foreign;
 611
 612                 $this->profiler = isset( $params['profiler'] )
 613                         ? $params['profiler']
 614                         : Profiler::instance(); // @TODO: remove global state
 615                 $this->trxProfiler = isset( $params['trxProfiler'] )
 616                         ? $params['trxProfiler']
 617                         : new TransactionProfiler();
 618
 619                 if ( $user ) {
 620                         $this->open( $server, $user, $password, $dbName );
 621                 }
 622
 623         }
 624
 625         /**
 626          * Called by serialize. Throw an exception when DB connection is serialized.
 627          * This causes problems on some database engines because the connection is
 628          * not restored on unserialize.
 629          */
 630         public function __sleep() {
 631                 throw new MWException( 'Database serialization may cause problems, since ' .
 632                         'the connection is not restored on wakeup.' );
 633         }
 634
 635         /**
 636          * Given a DB type, construct the name of the appropriate child class of
 637          * DatabaseBase. This is designed to replace all of the manual stuff like:
 638          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 639          * as well as validate against the canonical list of DB types we have
 640          *
 641          * This factory function is mostly useful for when you need to connect to a
 642          * database other than the MediaWiki default (such as for external auth,
 643          * an extension, et cetera). Do not use this to connect to the MediaWiki
 644          * database. Example uses in core:
 645          * @see LoadBalancer::reallyOpenConnection()
 646          * @see ForeignDBRepo::getMasterDB()
 647          * @see WebInstallerDBConnect::execute()
 648          *
 649          * @since 1.18
 650          *
 651          * @param string $dbType A possible DB type
 652          * @param array $p An array of options to pass to the constructor.
 653          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 654          * @throws MWException If the database driver or extension cannot be found
 655          * @return DatabaseBase|null DatabaseBase subclass or null
 656          */
 657         final public static function factory( $dbType, $p = [] ) {
 658                 global $wgCommandLineMode;
 659
 660                 $canonicalDBTypes = [
 661                         'mysql' => [ 'mysqli', 'mysql' ],
 662                         'postgres' => [],
 663                         'sqlite' => [],
 664                         'oracle' => [],
 665                         'mssql' => [],
 666                 ];
 667
 668                 $driver = false;
 669                 $dbType = strtolower( $dbType );
 670                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 671                         $possibleDrivers = $canonicalDBTypes[$dbType];
 672                         if ( !empty( $p['driver'] ) ) {
 673                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 674                                         $driver = $p['driver'];
 675                                 } else {
 676                                         throw new MWException( __METHOD__ .
 677                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 678                                 }
 679                         } else {
 680                                 foreach ( $possibleDrivers as $posDriver ) {
 681                                         if ( extension_loaded( $posDriver ) ) {
 682                                                 $driver = $posDriver;
 683                                                 break;
 684                                         }
 685                                 }
 686                         }
 687                 } else {
 688                         $driver = $dbType;
 689                 }
 690                 if ( $driver === false ) {
 691                         throw new MWException( __METHOD__ .
 692                                 " no viable database extension found for type '$dbType'" );
 693                 }
 694
 695                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 696                 // and everything else doesn't use a schema (e.g. null)
 697                 // Although postgres and oracle support schemas, we don't use them (yet)
 698                 // to maintain backwards compatibility
 699                 $defaultSchemas = [
 700                         'mssql' => 'get from global',
 701                 ];
 702
 703                 $class = 'Database' . ucfirst( $driver );
 704                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 705                         // Resolve some defaults for b/c
 706                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 707                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 708                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 709                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 710                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 711                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : [];
 712                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 713                         if ( !isset( $p['schema'] ) ) {
 714                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 715                         }
 716                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 717                         $p['cliMode'] = $wgCommandLineMode;
 718
 719                         return new $class( $p );
 720                 } else {
 721                         return null;
 722                 }
 723         }
 724
 725         protected function installErrorHandler() {
 726                 $this->mPHPError = false;
 727                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 728                 set_error_handler( [ $this, 'connectionErrorHandler' ] );
 729         }
 730
 731         /**
 732          * @return bool|string
 733          */
 734         protected function restoreErrorHandler() {
 735                 restore_error_handler();
 736                 if ( $this->htmlErrors !== false ) {
 737                         ini_set( 'html_errors', $this->htmlErrors );
 738                 }
 739                 if ( $this->mPHPError ) {
 740                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 741                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 742
 743                         return $error;
 744                 } else {
 745                         return false;
 746                 }
 747         }
 748
 749         /**
 750          * @param int $errno
 751          * @param string $errstr
 752          */
 753         public function connectionErrorHandler( $errno, $errstr ) {
 754                 $this->mPHPError = $errstr;
 755         }
 756
 757         /**
 758          * Create a log context to pass to wfLogDBError or other logging functions.
 759          *
 760          * @param array $extras Additional data to add to context
 761          * @return array
 762          */
 763         protected function getLogContext( array $extras = [] ) {
 764                 return array_merge(
 765                         [
 766                                 'db_server' => $this->mServer,
 767                                 'db_name' => $this->mDBname,
 768                                 'db_user' => $this->mUser,
 769                         ],
 770                         $extras
 771                 );
 772         }
 773
 774         public function close() {
 775                 if ( $this->mConn ) {
 776                         if ( $this->trxLevel() ) {
 777                                 if ( !$this->mTrxAutomatic ) {
 778                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 779                                                 " performing implicit commit before closing connection!" );
 780                                 }
 781
 782                                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 783                         }
 784
 785                         $closed = $this->closeConnection();
 786                         $this->mConn = false;
 787                 } elseif ( $this->mTrxIdleCallbacks || $this->mTrxEndCallbacks ) { // sanity
 788                         throw new MWException( "Transaction callbacks still pending." );
 789                 } else {
 790                         $closed = true;
 791                 }
 792                 $this->mOpened = false;
 793
 794                 return $closed;
 795         }
 796
 797         /**
 798          * Make sure isOpen() returns true as a sanity check
 799          *
 800          * @throws DBUnexpectedError
 801          */
 802         protected function assertOpen() {
 803                 if ( !$this->isOpen() ) {
 804                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 805                 }
 806         }
 807
 808         /**
 809          * Closes underlying database connection
 810          * @since 1.20
 811          * @return bool Whether connection was closed successfully
 812          */
 813         abstract protected function closeConnection();
 814
 815         function reportConnectionError( $error = 'Unknown error' ) {
 816                 $myError = $this->lastError();
 817                 if ( $myError ) {
 818                         $error = $myError;
 819                 }
 820
 821                 # New method
 822                 throw new DBConnectionError( $this, $error );
 823         }
 824
 825         /**
 826          * The DBMS-dependent part of query()
 827          *
 828          * @param string $sql SQL query.
 829          * @return ResultWrapper|bool Result object to feed to fetchObject,
 830          *   fetchRow, ...; or false on failure
 831          */
 832         abstract protected function doQuery( $sql );
 833
 834         /**
 835          * Determine whether a query writes to the DB.
 836          * Should return true if unsure.
 837          *
 838          * @param string $sql
 839          * @return bool
 840          */
 841         protected function isWriteQuery( $sql ) {
 842                 return !preg_match(
 843                         '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 844         }
 845
 846         /**
 847          * @param $sql
 848          * @return string|null
 849          */
 850         protected function getQueryVerb( $sql ) {
 851                 return preg_match( '/^\s*([a-z]+)/i', $sql, $m ) ? strtoupper( $m[1] ) : null;
 852         }
 853
 854         /**
 855          * Determine whether a SQL statement is sensitive to isolation level.
 856          * A SQL statement is considered transactable if its result could vary
 857          * depending on the transaction isolation level. Operational commands
 858          * such as 'SET' and 'SHOW' are not considered to be transactable.
 859          *
 860          * @param string $sql
 861          * @return bool
 862          */
 863         protected function isTransactableQuery( $sql ) {
 864                 $verb = $this->getQueryVerb( $sql );
 865                 return !in_array( $verb, [ 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ], true );
 866         }
 867
 868         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 869                 global $wgUser;
 870
 871                 $priorWritesPending = $this->writesOrCallbacksPending();
 872                 $this->mLastQuery = $sql;
 873
 874                 $isWrite = $this->isWriteQuery( $sql );
 875                 if ( $isWrite ) {
 876                         $reason = $this->getReadOnlyReason();
 877                         if ( $reason !== false ) {
 878                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 879                         }
 880                         # Set a flag indicating that writes have been done
 881                         $this->mDoneWrites = microtime( true );
 882                 }
 883
 884                 # Add a comment for easy SHOW PROCESSLIST interpretation
 885                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 886                         $userName = $wgUser->getName();
 887                         if ( mb_strlen( $userName ) > 15 ) {
 888                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 889                         }
 890                         $userName = str_replace( '/', '', $userName );
 891                 } else {
 892                         $userName = '';
 893                 }
 894
 895                 // Add trace comment to the begin of the sql string, right after the operator.
 896                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 897                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 898
 899                 # Start implicit transactions that wrap the request if DBO_TRX is enabled
 900                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX )
 901                         && $this->isTransactableQuery( $sql )
 902                 ) {
 903                         $this->begin( __METHOD__ . " ($fname)", self::TRANSACTION_INTERNAL );
 904                         $this->mTrxAutomatic = true;
 905                 }
 906
 907                 # Keep track of whether the transaction has write queries pending
 908                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWrite ) {
 909                         $this->mTrxDoneWrites = true;
 910                         $this->trxProfiler->transactionWritingIn(
 911                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 912                 }
 913
 914                 if ( $this->debug() ) {
 915                         wfDebugLog( 'queries', sprintf( "%s: %s", $this->mDBname, $commentedSql ) );
 916                 }
 917
 918                 # Avoid fatals if close() was called
 919                 $this->assertOpen();
 920
 921                 # Send the query to the server
 922                 $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 923
 924                 # Try reconnecting if the connection was lost
 925                 if ( false === $ret && $this->wasErrorReissuable() ) {
 926                         $recoverable = $this->canRecoverFromDisconnect( $sql, $priorWritesPending );
 927                         # Stash the last error values before anything might clear them
 928                         $lastError = $this->lastError();
 929                         $lastErrno = $this->lastErrno();
 930                         # Update state tracking to reflect transaction loss due to disconnection
 931                         $this->handleTransactionLoss();
 932                         wfDebug( "Connection lost, reconnecting...\n" );
 933                         if ( $this->reconnect() ) {
 934                                 wfDebug( "Reconnected\n" );
 935                                 $msg = __METHOD__ . ": lost connection to {$this->getServer()}; reconnected";
 936                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
 937
 938                                 if ( !$recoverable ) {
 939                                         # Callers may catch the exception and continue to use the DB
 940                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname );
 941                                 } else {
 942                                         # Should be safe to silently retry the query
 943                                         $ret = $this->doProfiledQuery( $sql, $commentedSql, $isWrite, $fname );
 944                                 }
 945                         } else {
 946                                 wfDebug( "Failed\n" );
 947                         }
 948                 }
 949
 950                 if ( false === $ret ) {
 951                         # Deadlocks cause the entire transaction to abort, not just the statement.
 952                         # http://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
 953                         # https://www.postgresql.org/docs/9.1/static/explicit-locking.html
 954                         if ( $this->wasDeadlock() ) {
 955                                 if ( $this->explicitTrxActive() || $priorWritesPending ) {
 956                                         $tempIgnore = false; // not recoverable
 957                                 }
 958                                 # Update state tracking to reflect transaction loss
 959                                 $this->handleTransactionLoss();
 960                         }
 961
 962                         $this->reportQueryError(
 963                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 964                 }
 965
 966                 $res = $this->resultObject( $ret );
 967
 968                 return $res;
 969         }
 970
 971         private function doProfiledQuery( $sql, $commentedSql, $isWrite, $fname ) {
 972                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 973                 # generalizeSQL() will probably cut down the query to reasonable
 974                 # logging size most of the time. The substr is really just a sanity check.
 975                 if ( $isMaster ) {
 976                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 977                 } else {
 978                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 979                 }
 980
 981                 # Include query transaction state
 982                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 983
 984                 $startTime = microtime( true );
 985                 $this->profiler->profileIn( $queryProf );
 986                 $ret = $this->doQuery( $commentedSql );
 987                 $this->profiler->profileOut( $queryProf );
 988                 $queryRuntime = max( microtime( true ) - $startTime, 0.0 );
 989
 990                 unset( $queryProfSection ); // profile out (if set)
 991
 992                 if ( $ret !== false ) {
 993                         $this->lastPing = $startTime;
 994                         if ( $isWrite && $this->mTrxLevel ) {
 995                                 $this->updateTrxWriteQueryTime( $sql, $queryRuntime );
 996                                 $this->mTrxWriteCallers[] = $fname;
 997                         }
 998                 }
 999
1000                 if ( $sql === self::PING_QUERY ) {
1001                         $this->mRTTEstimate = $queryRuntime;
1002                 }
1003
1004                 $this->trxProfiler->recordQueryCompletion(
1005                         $queryProf, $startTime, $isWrite, $this->affectedRows()
1006                 );
1007                 MWDebug::query( $sql, $fname, $isMaster, $queryRuntime );
1008
1009                 return $ret;
1010         }
1011
1012         /**
1013          * Update the estimated run-time of a query, not counting large row lock times
1014          *
1015          * LoadBalancer can be set to rollback transactions that will create huge replication
1016          * lag. It bases this estimate off of pendingWriteQueryDuration(). Certain simple
1017          * queries, like inserting a row can take a long time due to row locking. This method
1018          * uses some simple heuristics to discount those cases.
1019          *
1020          * @param string $sql A SQL write query
1021          * @param float $runtime Total runtime, including RTT
1022          */
1023         private function updateTrxWriteQueryTime( $sql, $runtime ) {
1024                 // Whether this is indicative of replica DB runtime (except for RBR or ws_repl)
1025                 $indicativeOfReplicaRuntime = true;
1026                 if ( $runtime > self::SLOW_WRITE_SEC ) {
1027                         $verb = $this->getQueryVerb( $sql );
1028                         // insert(), upsert(), replace() are fast unless bulky in size or blocked on locks
1029                         if ( $verb === 'INSERT' ) {
1030                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS;
1031                         } elseif ( $verb === 'REPLACE' ) {
1032                                 $indicativeOfReplicaRuntime = $this->affectedRows() > self::SMALL_WRITE_ROWS / 2;
1033                         }
1034                 }
1035
1036                 $this->mTrxWriteDuration += $runtime;
1037                 $this->mTrxWriteQueryCount += 1;
1038                 if ( $indicativeOfReplicaRuntime ) {
1039                         $this->mTrxWriteAdjDuration += $runtime;
1040                         $this->mTrxWriteAdjQueryCount += 1;
1041                 }
1042         }
1043
1044         private function canRecoverFromDisconnect( $sql, $priorWritesPending ) {
1045                 # Transaction dropped; this can mean lost writes, or REPEATABLE-READ snapshots.
1046                 # Dropped connections also mean that named locks are automatically released.
1047                 # Only allow error suppression in autocommit mode or when the lost transaction
1048                 # didn't matter anyway (aside from DBO_TRX snapshot loss).
1049                 if ( $this->mNamedLocksHeld ) {
1050                         return false; // possible critical section violation
1051                 } elseif ( $sql === 'COMMIT' ) {
1052                         return !$priorWritesPending; // nothing written anyway? (T127428)
1053                 } elseif ( $sql === 'ROLLBACK' ) {
1054                         return true; // transaction lost...which is also what was requested :)
1055                 } elseif ( $this->explicitTrxActive() ) {
1056                         return false; // don't drop atomocity
1057                 } elseif ( $priorWritesPending ) {
1058                         return false; // prior writes lost from implicit transaction
1059                 }
1060
1061                 return true;
1062         }
1063
1064         private function handleTransactionLoss() {
1065                 $this->mTrxLevel = 0;
1066                 $this->mTrxIdleCallbacks = []; // bug 65263
1067                 $this->mTrxPreCommitCallbacks = []; // bug 65263
1068                 try {
1069                         // Handle callbacks in mTrxEndCallbacks
1070                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
1071                         $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
1072                         return null;
1073                 } catch ( Exception $e ) {
1074                         // Already logged; move on...
1075                         return $e;
1076                 }
1077         }
1078
1079         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1080                 if ( $this->ignoreErrors() || $tempIgnore ) {
1081                         wfDebug( "SQL ERROR (ignored): $error\n" );
1082                 } else {
1083                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1084                         wfLogDBError(
1085                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1086                                 $this->getLogContext( [
1087                                         'method' => __METHOD__,
1088                                         'errno' => $errno,
1089                                         'error' => $error,
1090                                         'sql1line' => $sql1line,
1091                                         'fname' => $fname,
1092                                 ] )
1093                         );
1094                         wfDebug( "SQL ERROR: " . $error . "\n" );
1095                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1096                 }
1097         }
1098
1099         /**
1100          * Intended to be compatible with the PEAR::DB wrapper functions.
1101          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1102          *
1103          * ? = scalar value, quoted as necessary
1104          * ! = raw SQL bit (a function for instance)
1105          * & = filename; reads the file and inserts as a blob
1106          *     (we don't use this though...)
1107          *
1108          * @param string $sql
1109          * @param string $func
1110          *
1111          * @return array
1112          */
1113         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1114                 /* MySQL doesn't support prepared statements (yet), so just
1115                  * pack up the query for reference. We'll manually replace
1116                  * the bits later.
1117                  */
1118                 return [ 'query' => $sql, 'func' => $func ];
1119         }
1120
1121         /**
1122          * Free a prepared query, generated by prepare().
1123          * @param string $prepared
1124          */
1125         protected function freePrepared( $prepared ) {
1126                 /* No-op by default */
1127         }
1128
1129         /**
1130          * Execute a prepared query with the various arguments
1131          * @param string $prepared The prepared sql
1132          * @param mixed $args Either an array here, or put scalars as varargs
1133          *
1134          * @return ResultWrapper
1135          */
1136         public function execute( $prepared, $args = null ) {
1137                 if ( !is_array( $args ) ) {
1138                         # Pull the var args
1139                         $args = func_get_args();
1140                         array_shift( $args );
1141                 }
1142
1143                 $sql = $this->fillPrepared( $prepared['query'], $args );
1144
1145                 return $this->query( $sql, $prepared['func'] );
1146         }
1147
1148         /**
1149          * For faking prepared SQL statements on DBs that don't support it directly.
1150          *
1151          * @param string $preparedQuery A 'preparable' SQL statement
1152          * @param array $args Array of Arguments to fill it with
1153          * @return string Executable SQL
1154          */
1155         public function fillPrepared( $preparedQuery, $args ) {
1156                 reset( $args );
1157                 $this->preparedArgs =& $args;
1158
1159                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1160                         [ &$this, 'fillPreparedArg' ], $preparedQuery );
1161         }
1162
1163         /**
1164          * preg_callback func for fillPrepared()
1165          * The arguments should be in $this->preparedArgs and must not be touched
1166          * while we're doing this.
1167          *
1168          * @param array $matches
1169          * @throws DBUnexpectedError
1170          * @return string
1171          */
1172         protected function fillPreparedArg( $matches ) {
1173                 switch ( $matches[1] ) {
1174                         case '\\?':
1175                                 return '?';
1176                         case '\\!':
1177                                 return '!';
1178                         case '\\&':
1179                                 return '&';
1180                 }
1181
1182                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1183
1184                 switch ( $matches[1] ) {
1185                         case '?':
1186                                 return $this->addQuotes( $arg );
1187                         case '!':
1188                                 return $arg;
1189                         case '&':
1190                                 # return $this->addQuotes( file_get_contents( $arg ) );
1191                                 throw new DBUnexpectedError(
1192                                         $this,
1193                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1194                                 );
1195                         default:
1196                                 throw new DBUnexpectedError(
1197                                         $this,
1198                                         'Received invalid match. This should never happen!'
1199                                 );
1200                 }
1201         }
1202
1203         public function freeResult( $res ) {
1204         }
1205
1206         public function selectField(
1207                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
1208         ) {
1209                 if ( $var === '*' ) { // sanity
1210                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1211                 }
1212
1213                 if ( !is_array( $options ) ) {
1214                         $options = [ $options ];
1215                 }
1216
1217                 $options['LIMIT'] = 1;
1218
1219                 $res = $this->select( $table, $var, $cond, $fname, $options );
1220                 if ( $res === false || !$this->numRows( $res ) ) {
1221                         return false;
1222                 }
1223
1224                 $row = $this->fetchRow( $res );
1225
1226                 if ( $row !== false ) {
1227                         return reset( $row );
1228                 } else {
1229                         return false;
1230                 }
1231         }
1232
1233         public function selectFieldValues(
1234                 $table, $var, $cond = '', $fname = __METHOD__, $options = [], $join_conds = []
1235         ) {
1236                 if ( $var === '*' ) { // sanity
1237                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1238                 } elseif ( !is_string( $var ) ) { // sanity
1239                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1240                 }
1241
1242                 if ( !is_array( $options ) ) {
1243                         $options = [ $options ];
1244                 }
1245
1246                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1247                 if ( $res === false ) {
1248                         return false;
1249                 }
1250
1251                 $values = [];
1252                 foreach ( $res as $row ) {
1253                         $values[] = $row->$var;
1254                 }
1255
1256                 return $values;
1257         }
1258
1259         /**
1260          * Returns an optional USE INDEX clause to go after the table, and a
1261          * string to go at the end of the query.
1262          *
1263          * @param array $options Associative array of options to be turned into
1264          *   an SQL query, valid keys are listed in the function.
1265          * @return array
1266          * @see DatabaseBase::select()
1267          */
1268         public function makeSelectOptions( $options ) {
1269                 $preLimitTail = $postLimitTail = '';
1270                 $startOpts = '';
1271
1272                 $noKeyOptions = [];
1273
1274                 foreach ( $options as $key => $option ) {
1275                         if ( is_numeric( $key ) ) {
1276                                 $noKeyOptions[$option] = true;
1277                         }
1278                 }
1279
1280                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1281
1282                 $preLimitTail .= $this->makeOrderBy( $options );
1283
1284                 // if (isset($options['LIMIT'])) {
1285                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1286                 //              isset($options['OFFSET']) ? $options['OFFSET']
1287                 //              : false);
1288                 // }
1289
1290                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1291                         $postLimitTail .= ' FOR UPDATE';
1292                 }
1293
1294                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1295                         $postLimitTail .= ' LOCK IN SHARE MODE';
1296                 }
1297
1298                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1299                         $startOpts .= 'DISTINCT';
1300                 }
1301
1302                 # Various MySQL extensions
1303                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1304                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1305                 }
1306
1307                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1308                         $startOpts .= ' HIGH_PRIORITY';
1309                 }
1310
1311                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1312                         $startOpts .= ' SQL_BIG_RESULT';
1313                 }
1314
1315                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1316                         $startOpts .= ' SQL_BUFFER_RESULT';
1317                 }
1318
1319                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1320                         $startOpts .= ' SQL_SMALL_RESULT';
1321                 }
1322
1323                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1324                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1325                 }
1326
1327                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1328                         $startOpts .= ' SQL_CACHE';
1329                 }
1330
1331                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1332                         $startOpts .= ' SQL_NO_CACHE';
1333                 }
1334
1335                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1336                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1337                 } else {
1338                         $useIndex = '';
1339                 }
1340                 if ( isset( $options['IGNORE INDEX'] ) && is_string( $options['IGNORE INDEX'] ) ) {
1341                         $ignoreIndex = $this->ignoreIndexClause( $options['IGNORE INDEX'] );
1342                 } else {
1343                         $ignoreIndex = '';
1344                 }
1345
1346                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1347         }
1348
1349         /**
1350          * Returns an optional GROUP BY with an optional HAVING
1351          *
1352          * @param array $options Associative array of options
1353          * @return string
1354          * @see DatabaseBase::select()
1355          * @since 1.21
1356          */
1357         public function makeGroupByWithHaving( $options ) {
1358                 $sql = '';
1359                 if ( isset( $options['GROUP BY'] ) ) {
1360                         $gb = is_array( $options['GROUP BY'] )
1361                                 ? implode( ',', $options['GROUP BY'] )
1362                                 : $options['GROUP BY'];
1363                         $sql .= ' GROUP BY ' . $gb;
1364                 }
1365                 if ( isset( $options['HAVING'] ) ) {
1366                         $having = is_array( $options['HAVING'] )
1367                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1368                                 : $options['HAVING'];
1369                         $sql .= ' HAVING ' . $having;
1370                 }
1371
1372                 return $sql;
1373         }
1374
1375         /**
1376          * Returns an optional ORDER BY
1377          *
1378          * @param array $options Associative array of options
1379          * @return string
1380          * @see DatabaseBase::select()
1381          * @since 1.21
1382          */
1383         public function makeOrderBy( $options ) {
1384                 if ( isset( $options['ORDER BY'] ) ) {
1385                         $ob = is_array( $options['ORDER BY'] )
1386                                 ? implode( ',', $options['ORDER BY'] )
1387                                 : $options['ORDER BY'];
1388
1389                         return ' ORDER BY ' . $ob;
1390                 }
1391
1392                 return '';
1393         }
1394
1395         // See IDatabase::select for the docs for this function
1396         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1397                 $options = [], $join_conds = [] ) {
1398                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1399
1400                 return $this->query( $sql, $fname );
1401         }
1402
1403         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1404                 $options = [], $join_conds = []
1405         ) {
1406                 if ( is_array( $vars ) ) {
1407                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1408                 }
1409
1410                 $options = (array)$options;
1411                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1412                         ? $options['USE INDEX']
1413                         : [];
1414                 $ignoreIndexes = ( isset( $options['IGNORE INDEX'] ) && is_array( $options['IGNORE INDEX'] ) )
1415                         ? $options['IGNORE INDEX']
1416                         : [];
1417
1418                 if ( is_array( $table ) ) {
1419                         $from = ' FROM ' .
1420                                 $this->tableNamesWithIndexClauseOrJOIN( $table, $useIndexes, $ignoreIndexes, $join_conds );
1421                 } elseif ( $table != '' ) {
1422                         if ( $table[0] == ' ' ) {
1423                                 $from = ' FROM ' . $table;
1424                         } else {
1425                                 $from = ' FROM ' .
1426                                         $this->tableNamesWithIndexClauseOrJOIN( [ $table ], $useIndexes, $ignoreIndexes, [] );
1427                         }
1428                 } else {
1429                         $from = '';
1430                 }
1431
1432                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ) =
1433                         $this->makeSelectOptions( $options );
1434
1435                 if ( !empty( $conds ) ) {
1436                         if ( is_array( $conds ) ) {
1437                                 $conds = $this->makeList( $conds, LIST_AND );
1438                         }
1439                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex WHERE $conds $preLimitTail";
1440                 } else {
1441                         $sql = "SELECT $startOpts $vars $from $useIndex $ignoreIndex $preLimitTail";
1442                 }
1443
1444                 if ( isset( $options['LIMIT'] ) ) {
1445                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1446                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1447                 }
1448                 $sql = "$sql $postLimitTail";
1449
1450                 if ( isset( $options['EXPLAIN'] ) ) {
1451                         $sql = 'EXPLAIN ' . $sql;
1452                 }
1453
1454                 return $sql;
1455         }
1456
1457         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1458                 $options = [], $join_conds = []
1459         ) {
1460                 $options = (array)$options;
1461                 $options['LIMIT'] = 1;
1462                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1463
1464                 if ( $res === false ) {
1465                         return false;
1466                 }
1467
1468                 if ( !$this->numRows( $res ) ) {
1469                         return false;
1470                 }
1471
1472                 $obj = $this->fetchObject( $res );
1473
1474                 return $obj;
1475         }
1476
1477         public function estimateRowCount(
1478                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
1479         ) {
1480                 $rows = 0;
1481                 $res = $this->select( $table, [ 'rowcount' => 'COUNT(*)' ], $conds, $fname, $options );
1482
1483                 if ( $res ) {
1484                         $row = $this->fetchRow( $res );
1485                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1486                 }
1487
1488                 return $rows;
1489         }
1490
1491         public function selectRowCount(
1492                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
1493         ) {
1494                 $rows = 0;
1495                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1496                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1497
1498                 if ( $res ) {
1499                         $row = $this->fetchRow( $res );
1500                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1501                 }
1502
1503                 return $rows;
1504         }
1505
1506         /**
1507          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1508          * It's only slightly flawed. Don't use for anything important.
1509          *
1510          * @param string $sql A SQL Query
1511          *
1512          * @return string
1513          */
1514         protected static function generalizeSQL( $sql ) {
1515                 # This does the same as the regexp below would do, but in such a way
1516                 # as to avoid crashing php on some large strings.
1517                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1518
1519                 $sql = str_replace( "\\\\", '', $sql );
1520                 $sql = str_replace( "\\'", '', $sql );
1521                 $sql = str_replace( "\\\"", '', $sql );
1522                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1523                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1524
1525                 # All newlines, tabs, etc replaced by single space
1526                 $sql = preg_replace( '/\s+/', ' ', $sql );
1527
1528                 # All numbers => N,
1529                 # except the ones surrounded by characters, e.g. l10n
1530                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1531                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1532
1533                 return $sql;
1534         }
1535
1536         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1537                 $info = $this->fieldInfo( $table, $field );
1538
1539                 return (bool)$info;
1540         }
1541
1542         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1543                 if ( !$this->tableExists( $table ) ) {
1544                         return null;
1545                 }
1546
1547                 $info = $this->indexInfo( $table, $index, $fname );
1548                 if ( is_null( $info ) ) {
1549                         return null;
1550                 } else {
1551                         return $info !== false;
1552                 }
1553         }
1554
1555         public function tableExists( $table, $fname = __METHOD__ ) {
1556                 $table = $this->tableName( $table );
1557                 $old = $this->ignoreErrors( true );
1558                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1559                 $this->ignoreErrors( $old );
1560
1561                 return (bool)$res;
1562         }
1563
1564         public function indexUnique( $table, $index ) {
1565                 $indexInfo = $this->indexInfo( $table, $index );
1566
1567                 if ( !$indexInfo ) {
1568                         return null;
1569                 }
1570
1571                 return !$indexInfo[0]->Non_unique;
1572         }
1573
1574         /**
1575          * Helper for DatabaseBase::insert().
1576          *
1577          * @param array $options
1578          * @return string
1579          */
1580         protected function makeInsertOptions( $options ) {
1581                 return implode( ' ', $options );
1582         }
1583
1584         public function insert( $table, $a, $fname = __METHOD__, $options = [] ) {
1585                 # No rows to insert, easy just return now
1586                 if ( !count( $a ) ) {
1587                         return true;
1588                 }
1589
1590                 $table = $this->tableName( $table );
1591
1592                 if ( !is_array( $options ) ) {
1593                         $options = [ $options ];
1594                 }
1595
1596                 $fh = null;
1597                 if ( isset( $options['fileHandle'] ) ) {
1598                         $fh = $options['fileHandle'];
1599                 }
1600                 $options = $this->makeInsertOptions( $options );
1601
1602                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1603                         $multi = true;
1604                         $keys = array_keys( $a[0] );
1605                 } else {
1606                         $multi = false;
1607                         $keys = array_keys( $a );
1608                 }
1609
1610                 $sql = 'INSERT ' . $options .
1611                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1612
1613                 if ( $multi ) {
1614                         $first = true;
1615                         foreach ( $a as $row ) {
1616                                 if ( $first ) {
1617                                         $first = false;
1618                                 } else {
1619                                         $sql .= ',';
1620                                 }
1621                                 $sql .= '(' . $this->makeList( $row ) . ')';
1622                         }
1623                 } else {
1624                         $sql .= '(' . $this->makeList( $a ) . ')';
1625                 }
1626
1627                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1628                         return false;
1629                 } elseif ( $fh !== null ) {
1630                         return true;
1631                 }
1632
1633                 return (bool)$this->query( $sql, $fname );
1634         }
1635
1636         /**
1637          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1638          *
1639          * @param array $options
1640          * @return array
1641          */
1642         protected function makeUpdateOptionsArray( $options ) {
1643                 if ( !is_array( $options ) ) {
1644                         $options = [ $options ];
1645                 }
1646
1647                 $opts = [];
1648
1649                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1650                         $opts[] = $this->lowPriorityOption();
1651                 }
1652
1653                 if ( in_array( 'IGNORE', $options ) ) {
1654                         $opts[] = 'IGNORE';
1655                 }
1656
1657                 return $opts;
1658         }
1659
1660         /**
1661          * Make UPDATE options for the DatabaseBase::update function
1662          *
1663          * @param array $options The options passed to DatabaseBase::update
1664          * @return string
1665          */
1666         protected function makeUpdateOptions( $options ) {
1667                 $opts = $this->makeUpdateOptionsArray( $options );
1668
1669                 return implode( ' ', $opts );
1670         }
1671
1672         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
1673                 $table = $this->tableName( $table );
1674                 $opts = $this->makeUpdateOptions( $options );
1675                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1676
1677                 if ( $conds !== [] && $conds !== '*' ) {
1678                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1679                 }
1680
1681                 return $this->query( $sql, $fname );
1682         }
1683
1684         public function makeList( $a, $mode = LIST_COMMA ) {
1685                 if ( !is_array( $a ) ) {
1686                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1687                 }
1688
1689                 $first = true;
1690                 $list = '';
1691
1692                 foreach ( $a as $field => $value ) {
1693                         if ( !$first ) {
1694                                 if ( $mode == LIST_AND ) {
1695                                         $list .= ' AND ';
1696                                 } elseif ( $mode == LIST_OR ) {
1697                                         $list .= ' OR ';
1698                                 } else {
1699                                         $list .= ',';
1700                                 }
1701                         } else {
1702                                 $first = false;
1703                         }
1704
1705                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1706                                 $list .= "($value)";
1707                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1708                                 $list .= "$value";
1709                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1710                                 // Remove null from array to be handled separately if found
1711                                 $includeNull = false;
1712                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1713                                         $includeNull = true;
1714                                         unset( $value[$nullKey] );
1715                                 }
1716                                 if ( count( $value ) == 0 && !$includeNull ) {
1717                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1718                                 } elseif ( count( $value ) == 0 ) {
1719                                         // only check if $field is null
1720                                         $list .= "$field IS NULL";
1721                                 } else {
1722                                         // IN clause contains at least one valid element
1723                                         if ( $includeNull ) {
1724                                                 // Group subconditions to ensure correct precedence
1725                                                 $list .= '(';
1726                                         }
1727                                         if ( count( $value ) == 1 ) {
1728                                                 // Special-case single values, as IN isn't terribly efficient
1729                                                 // Don't necessarily assume the single key is 0; we don't
1730                                                 // enforce linear numeric ordering on other arrays here.
1731                                                 $value = array_values( $value )[0];
1732                                                 $list .= $field . " = " . $this->addQuotes( $value );
1733                                         } else {
1734                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1735                                         }
1736                                         // if null present in array, append IS NULL
1737                                         if ( $includeNull ) {
1738                                                 $list .= " OR $field IS NULL)";
1739                                         }
1740                                 }
1741                         } elseif ( $value === null ) {
1742                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1743                                         $list .= "$field IS ";
1744                                 } elseif ( $mode == LIST_SET ) {
1745                                         $list .= "$field = ";
1746                                 }
1747                                 $list .= 'NULL';
1748                         } else {
1749                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1750                                         $list .= "$field = ";
1751                                 }
1752                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1753                         }
1754                 }
1755
1756                 return $list;
1757         }
1758
1759         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1760                 $conds = [];
1761
1762                 foreach ( $data as $base => $sub ) {
1763                         if ( count( $sub ) ) {
1764                                 $conds[] = $this->makeList(
1765                                         [ $baseKey => $base, $subKey => array_keys( $sub ) ],
1766                                         LIST_AND );
1767                         }
1768                 }
1769
1770                 if ( $conds ) {
1771                         return $this->makeList( $conds, LIST_OR );
1772                 } else {
1773                         // Nothing to search for...
1774                         return false;
1775                 }
1776         }
1777
1778         /**
1779          * Return aggregated value alias
1780          *
1781          * @param array $valuedata
1782          * @param string $valuename
1783          *
1784          * @return string
1785          */
1786         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1787                 return $valuename;
1788         }
1789
1790         public function bitNot( $field ) {
1791                 return "(~$field)";
1792         }
1793
1794         public function bitAnd( $fieldLeft, $fieldRight ) {
1795                 return "($fieldLeft & $fieldRight)";
1796         }
1797
1798         public function bitOr( $fieldLeft, $fieldRight ) {
1799                 return "($fieldLeft | $fieldRight)";
1800         }
1801
1802         public function buildConcat( $stringList ) {
1803                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1804         }
1805
1806         public function buildGroupConcatField(
1807                 $delim, $table, $field, $conds = '', $join_conds = []
1808         ) {
1809                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1810
1811                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1812         }
1813
1814         /**
1815          * @param string $field Field or column to cast
1816          * @return string
1817          * @since 1.28
1818          */
1819         public function buildStringCast( $field ) {
1820                 return $field;
1821         }
1822
1823         public function selectDB( $db ) {
1824                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1825                 # if your database engine supports a concept similar to MySQL's
1826                 # databases you may as well.
1827                 $this->mDBname = $db;
1828
1829                 return true;
1830         }
1831
1832         public function getDBname() {
1833                 return $this->mDBname;
1834         }
1835
1836         public function getServer() {
1837                 return $this->mServer;
1838         }
1839
1840         /**
1841          * Format a table name ready for use in constructing an SQL query
1842          *
1843          * This does two important things: it quotes the table names to clean them up,
1844          * and it adds a table prefix if only given a table name with no quotes.
1845          *
1846          * All functions of this object which require a table name call this function
1847          * themselves. Pass the canonical name to such functions. This is only needed
1848          * when calling query() directly.
1849          *
1850          * @note This function does not sanitize user input. It is not safe to use
1851          *   this function to escape user input.
1852          * @param string $name Database table name
1853          * @param string $format One of:
1854          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1855          *            so that it can be used in a query.
1856          *   raw - Do not add identifier quotes to the table name
1857          * @return string Full database name
1858          */
1859         public function tableName( $name, $format = 'quoted' ) {
1860                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1861                 # Skip the entire process when we have a string quoted on both ends.
1862                 # Note that we check the end so that we will still quote any use of
1863                 # use of `database`.table. But won't break things if someone wants
1864                 # to query a database table with a dot in the name.
1865                 if ( $this->isQuotedIdentifier( $name ) ) {
1866                         return $name;
1867                 }
1868
1869                 # Lets test for any bits of text that should never show up in a table
1870                 # name. Basically anything like JOIN or ON which are actually part of
1871                 # SQL queries, but may end up inside of the table value to combine
1872                 # sql. Such as how the API is doing.
1873                 # Note that we use a whitespace test rather than a \b test to avoid
1874                 # any remote case where a word like on may be inside of a table name
1875                 # surrounded by symbols which may be considered word breaks.
1876                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1877                         return $name;
1878                 }
1879
1880                 # Split database and table into proper variables.
1881                 # We reverse the explode so that database.table and table both output
1882                 # the correct table.
1883                 $dbDetails = explode( '.', $name, 3 );
1884                 if ( count( $dbDetails ) == 3 ) {
1885                         list( $database, $schema, $table ) = $dbDetails;
1886                         # We don't want any prefix added in this case
1887                         $prefix = '';
1888                 } elseif ( count( $dbDetails ) == 2 ) {
1889                         list( $database, $table ) = $dbDetails;
1890                         # We don't want any prefix added in this case
1891                         # In dbs that support it, $database may actually be the schema
1892                         # but that doesn't affect any of the functionality here
1893                         $prefix = '';
1894                         $schema = null;
1895                 } else {
1896                         list( $table ) = $dbDetails;
1897                         if ( $wgSharedDB !== null # We have a shared database
1898                                 && $this->mForeign == false # We're not working on a foreign database
1899                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1900                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1901                         ) {
1902                                 $database = $wgSharedDB;
1903                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1904                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1905                         } else {
1906                                 $database = null;
1907                                 $schema = $this->mSchema; # Default schema
1908                                 $prefix = $this->mTablePrefix; # Default prefix
1909                         }
1910                 }
1911
1912                 # Quote $table and apply the prefix if not quoted.
1913                 # $tableName might be empty if this is called from Database::replaceVars()
1914                 $tableName = "{$prefix}{$table}";
1915                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1916                         $tableName = $this->addIdentifierQuotes( $tableName );
1917                 }
1918
1919                 # Quote $schema and merge it with the table name if needed
1920                 if ( strlen( $schema ) ) {
1921                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1922                                 $schema = $this->addIdentifierQuotes( $schema );
1923                         }
1924                         $tableName = $schema . '.' . $tableName;
1925                 }
1926
1927                 # Quote $database and merge it with the table name if needed
1928                 if ( $database !== null ) {
1929                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1930                                 $database = $this->addIdentifierQuotes( $database );
1931                         }
1932                         $tableName = $database . '.' . $tableName;
1933                 }
1934
1935                 return $tableName;
1936         }
1937
1938         /**
1939          * Fetch a number of table names into an array
1940          * This is handy when you need to construct SQL for joins
1941          *
1942          * Example:
1943          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1944          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1945          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1946          *
1947          * @return array
1948          */
1949         public function tableNames() {
1950                 $inArray = func_get_args();
1951                 $retVal = [];
1952
1953                 foreach ( $inArray as $name ) {
1954                         $retVal[$name] = $this->tableName( $name );
1955                 }
1956
1957                 return $retVal;
1958         }
1959
1960         /**
1961          * Fetch a number of table names into an zero-indexed numerical array
1962          * This is handy when you need to construct SQL for joins
1963          *
1964          * Example:
1965          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1966          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1967          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1968          *
1969          * @return array
1970          */
1971         public function tableNamesN() {
1972                 $inArray = func_get_args();
1973                 $retVal = [];
1974
1975                 foreach ( $inArray as $name ) {
1976                         $retVal[] = $this->tableName( $name );
1977                 }
1978
1979                 return $retVal;
1980         }
1981
1982         /**
1983          * Get an aliased table name
1984          * e.g. tableName AS newTableName
1985          *
1986          * @param string $name Table name, see tableName()
1987          * @param string|bool $alias Alias (optional)
1988          * @return string SQL name for aliased table. Will not alias a table to its own name
1989          */
1990         public function tableNameWithAlias( $name, $alias = false ) {
1991                 if ( !$alias || $alias == $name ) {
1992                         return $this->tableName( $name );
1993                 } else {
1994                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1995                 }
1996         }
1997
1998         /**
1999          * Gets an array of aliased table names
2000          *
2001          * @param array $tables [ [alias] => table ]
2002          * @return string[] See tableNameWithAlias()
2003          */
2004         public function tableNamesWithAlias( $tables ) {
2005                 $retval = [];
2006                 foreach ( $tables as $alias => $table ) {
2007                         if ( is_numeric( $alias ) ) {
2008                                 $alias = $table;
2009                         }
2010                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2011                 }
2012
2013                 return $retval;
2014         }
2015
2016         /**
2017          * Get an aliased field name
2018          * e.g. fieldName AS newFieldName
2019          *
2020          * @param string $name Field name
2021          * @param string|bool $alias Alias (optional)
2022          * @return string SQL name for aliased field. Will not alias a field to its own name
2023          */
2024         public function fieldNameWithAlias( $name, $alias = false ) {
2025                 if ( !$alias || (string)$alias === (string)$name ) {
2026                         return $name;
2027                 } else {
2028                         return $name . ' AS ' . $this->addIdentifierQuotes( $alias ); // PostgreSQL needs AS
2029                 }
2030         }
2031
2032         /**
2033          * Gets an array of aliased field names
2034          *
2035          * @param array $fields [ [alias] => field ]
2036          * @return string[] See fieldNameWithAlias()
2037          */
2038         public function fieldNamesWithAlias( $fields ) {
2039                 $retval = [];
2040                 foreach ( $fields as $alias => $field ) {
2041                         if ( is_numeric( $alias ) ) {
2042                                 $alias = $field;
2043                         }
2044                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2045                 }
2046
2047                 return $retval;
2048         }
2049
2050         /**
2051          * Get the aliased table name clause for a FROM clause
2052          * which might have a JOIN and/or USE INDEX or IGNORE INDEX clause
2053          *
2054          * @param array $tables ( [alias] => table )
2055          * @param array $use_index Same as for select()
2056          * @param array $ignore_index Same as for select()
2057          * @param array $join_conds Same as for select()
2058          * @return string
2059          */
2060         protected function tableNamesWithIndexClauseOrJOIN(
2061                 $tables, $use_index = [], $ignore_index = [], $join_conds = []
2062         ) {
2063                 $ret = [];
2064                 $retJOIN = [];
2065                 $use_index = (array)$use_index;
2066                 $ignore_index = (array)$ignore_index;
2067                 $join_conds = (array)$join_conds;
2068
2069                 foreach ( $tables as $alias => $table ) {
2070                         if ( !is_string( $alias ) ) {
2071                                 // No alias? Set it equal to the table name
2072                                 $alias = $table;
2073                         }
2074                         // Is there a JOIN clause for this table?
2075                         if ( isset( $join_conds[$alias] ) ) {
2076                                 list( $joinType, $conds ) = $join_conds[$alias];
2077                                 $tableClause = $joinType;
2078                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2079                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2080                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2081                                         if ( $use != '' ) {
2082                                                 $tableClause .= ' ' . $use;
2083                                         }
2084                                 }
2085                                 if ( isset( $ignore_index[$alias] ) ) { // has IGNORE INDEX?
2086                                         $ignore = $this->ignoreIndexClause( implode( ',', (array)$ignore_index[$alias] ) );
2087                                         if ( $ignore != '' ) {
2088                                                 $tableClause .= ' ' . $ignore;
2089                                         }
2090                                 }
2091                                 $on = $this->makeList( (array)$conds, LIST_AND );
2092                                 if ( $on != '' ) {
2093                                         $tableClause .= ' ON (' . $on . ')';
2094                                 }
2095
2096                                 $retJOIN[] = $tableClause;
2097                         } elseif ( isset( $use_index[$alias] ) ) {
2098                                 // Is there an INDEX clause for this table?
2099                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2100                                 $tableClause .= ' ' . $this->useIndexClause(
2101                                         implode( ',', (array)$use_index[$alias] )
2102                                 );
2103
2104                                 $ret[] = $tableClause;
2105                         } elseif ( isset( $ignore_index[$alias] ) ) {
2106                                 // Is there an INDEX clause for this table?
2107                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2108                                 $tableClause .= ' ' . $this->ignoreIndexClause(
2109                                         implode( ',', (array)$ignore_index[$alias] )
2110                                 );
2111
2112                                 $ret[] = $tableClause;
2113                         } else {
2114                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2115
2116                                 $ret[] = $tableClause;
2117                         }
2118                 }
2119
2120                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2121                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2122                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2123
2124                 // Compile our final table clause
2125                 return implode( ' ', [ $implicitJoins, $explicitJoins ] );
2126         }
2127
2128         /**
2129          * Get the name of an index in a given table.
2130          *
2131          * @param string $index
2132          * @return string
2133          */
2134         protected function indexName( $index ) {
2135                 // Backwards-compatibility hack
2136                 $renamed = [
2137                         'ar_usertext_timestamp' => 'usertext_timestamp',
2138                         'un_user_id' => 'user_id',
2139                         'un_user_ip' => 'user_ip',
2140                 ];
2141
2142                 if ( isset( $renamed[$index] ) ) {
2143                         return $renamed[$index];
2144                 } else {
2145                         return $index;
2146                 }
2147         }
2148
2149         public function addQuotes( $s ) {
2150                 if ( $s instanceof Blob ) {
2151                         $s = $s->fetch();
2152                 }
2153                 if ( $s === null ) {
2154                         return 'NULL';
2155                 } else {
2156                         # This will also quote numeric values. This should be harmless,
2157                         # and protects against weird problems that occur when they really
2158                         # _are_ strings such as article titles and string->number->string
2159                         # conversion is not 1:1.
2160                         return "'" . $this->strencode( $s ) . "'";
2161                 }
2162         }
2163
2164         /**
2165          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2166          * MySQL uses `backticks` while basically everything else uses double quotes.
2167          * Since MySQL is the odd one out here the double quotes are our generic
2168          * and we implement backticks in DatabaseMysql.
2169          *
2170          * @param string $s
2171          * @return string
2172          */
2173         public function addIdentifierQuotes( $s ) {
2174                 return '"' . str_replace( '"', '""', $s ) . '"';
2175         }
2176
2177         /**
2178          * Returns if the given identifier looks quoted or not according to
2179          * the database convention for quoting identifiers .
2180          *
2181          * @note Do not use this to determine if untrusted input is safe.
2182          *   A malicious user can trick this function.
2183          * @param string $name
2184          * @return bool
2185          */
2186         public function isQuotedIdentifier( $name ) {
2187                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2188         }
2189
2190         /**
2191          * @param string $s
2192          * @return string
2193          */
2194         protected function escapeLikeInternal( $s ) {
2195                 return addcslashes( $s, '\%_' );
2196         }
2197
2198         public function buildLike() {
2199                 $params = func_get_args();
2200
2201                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2202                         $params = $params[0];
2203                 }
2204
2205                 $s = '';
2206
2207                 foreach ( $params as $value ) {
2208                         if ( $value instanceof LikeMatch ) {
2209                                 $s .= $value->toString();
2210                         } else {
2211                                 $s .= $this->escapeLikeInternal( $value );
2212                         }
2213                 }
2214
2215                 return " LIKE {$this->addQuotes( $s )} ";
2216         }
2217
2218         public function anyChar() {
2219                 return new LikeMatch( '_' );
2220         }
2221
2222         public function anyString() {
2223                 return new LikeMatch( '%' );
2224         }
2225
2226         public function nextSequenceValue( $seqName ) {
2227                 return null;
2228         }
2229
2230         /**
2231          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2232          * is only needed because a) MySQL must be as efficient as possible due to
2233          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2234          * which index to pick. Anyway, other databases might have different
2235          * indexes on a given table. So don't bother overriding this unless you're
2236          * MySQL.
2237          * @param string $index
2238          * @return string
2239          */
2240         public function useIndexClause( $index ) {
2241                 return '';
2242         }
2243
2244         /**
2245          * IGNORE INDEX clause. Unlikely to be useful for anything but MySQL. This
2246          * is only needed because a) MySQL must be as efficient as possible due to
2247          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2248          * which index to pick. Anyway, other databases might have different
2249          * indexes on a given table. So don't bother overriding this unless you're
2250          * MySQL.
2251          * @param string $index
2252          * @return string
2253          */
2254         public function ignoreIndexClause( $index ) {
2255                 return '';
2256         }
2257
2258         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2259                 $quotedTable = $this->tableName( $table );
2260
2261                 if ( count( $rows ) == 0 ) {
2262                         return;
2263                 }
2264
2265                 # Single row case
2266                 if ( !is_array( reset( $rows ) ) ) {
2267                         $rows = [ $rows ];
2268                 }
2269
2270                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2271                 foreach ( $rows as $row ) {
2272                         # Delete rows which collide
2273                         if ( $uniqueIndexes ) {
2274                                 $sql = "DELETE FROM $quotedTable WHERE ";
2275                                 $first = true;
2276                                 foreach ( $uniqueIndexes as $index ) {
2277                                         if ( $first ) {
2278                                                 $first = false;
2279                                                 $sql .= '( ';
2280                                         } else {
2281                                                 $sql .= ' ) OR ( ';
2282                                         }
2283                                         if ( is_array( $index ) ) {
2284                                                 $first2 = true;
2285                                                 foreach ( $index as $col ) {
2286                                                         if ( $first2 ) {
2287                                                                 $first2 = false;
2288                                                         } else {
2289                                                                 $sql .= ' AND ';
2290                                                         }
2291                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2292                                                 }
2293                                         } else {
2294                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2295                                         }
2296                                 }
2297                                 $sql .= ' )';
2298                                 $this->query( $sql, $fname );
2299                         }
2300
2301                         # Now insert the row
2302                         $this->insert( $table, $row, $fname );
2303                 }
2304         }
2305
2306         /**
2307          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2308          * statement.
2309          *
2310          * @param string $table Table name
2311          * @param array|string $rows Row(s) to insert
2312          * @param string $fname Caller function name
2313          *
2314          * @return ResultWrapper
2315          */
2316         protected function nativeReplace( $table, $rows, $fname ) {
2317                 $table = $this->tableName( $table );
2318
2319                 # Single row case
2320                 if ( !is_array( reset( $rows ) ) ) {
2321                         $rows = [ $rows ];
2322                 }
2323
2324                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2325                 $first = true;
2326
2327                 foreach ( $rows as $row ) {
2328                         if ( $first ) {
2329                                 $first = false;
2330                         } else {
2331                                 $sql .= ',';
2332                         }
2333
2334                         $sql .= '(' . $this->makeList( $row ) . ')';
2335                 }
2336
2337                 return $this->query( $sql, $fname );
2338         }
2339
2340         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2341                 $fname = __METHOD__
2342         ) {
2343                 if ( !count( $rows ) ) {
2344                         return true; // nothing to do
2345                 }
2346
2347                 if ( !is_array( reset( $rows ) ) ) {
2348                         $rows = [ $rows ];
2349                 }
2350
2351                 if ( count( $uniqueIndexes ) ) {
2352                         $clauses = []; // list WHERE clauses that each identify a single row
2353                         foreach ( $rows as $row ) {
2354                                 foreach ( $uniqueIndexes as $index ) {
2355                                         $index = is_array( $index ) ? $index : [ $index ]; // columns
2356                                         $rowKey = []; // unique key to this row
2357                                         foreach ( $index as $column ) {
2358                                                 $rowKey[$column] = $row[$column];
2359                                         }
2360                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2361                                 }
2362                         }
2363                         $where = [ $this->makeList( $clauses, LIST_OR ) ];
2364                 } else {
2365                         $where = false;
2366                 }
2367
2368                 $useTrx = !$this->mTrxLevel;
2369                 if ( $useTrx ) {
2370                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2371                 }
2372                 try {
2373                         # Update any existing conflicting row(s)
2374                         if ( $where !== false ) {
2375                                 $ok = $this->update( $table, $set, $where, $fname );
2376                         } else {
2377                                 $ok = true;
2378                         }
2379                         # Now insert any non-conflicting row(s)
2380                         $ok = $this->insert( $table, $rows, $fname, [ 'IGNORE' ] ) && $ok;
2381                 } catch ( Exception $e ) {
2382                         if ( $useTrx ) {
2383                                 $this->rollback( $fname, self::FLUSHING_INTERNAL );
2384                         }
2385                         throw $e;
2386                 }
2387                 if ( $useTrx ) {
2388                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2389                 }
2390
2391                 return $ok;
2392         }
2393
2394         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2395                 $fname = __METHOD__
2396         ) {
2397                 if ( !$conds ) {
2398                         throw new DBUnexpectedError( $this,
2399                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2400                 }
2401
2402                 $delTable = $this->tableName( $delTable );
2403                 $joinTable = $this->tableName( $joinTable );
2404                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2405                 if ( $conds != '*' ) {
2406                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2407                 }
2408                 $sql .= ')';
2409
2410                 $this->query( $sql, $fname );
2411         }
2412
2413         /**
2414          * Returns the size of a text field, or -1 for "unlimited"
2415          *
2416          * @param string $table
2417          * @param string $field
2418          * @return int
2419          */
2420         public function textFieldSize( $table, $field ) {
2421                 $table = $this->tableName( $table );
2422                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2423                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2424                 $row = $this->fetchObject( $res );
2425
2426                 $m = [];
2427
2428                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2429                         $size = $m[1];
2430                 } else {
2431                         $size = -1;
2432                 }
2433
2434                 return $size;
2435         }
2436
2437         /**
2438          * A string to insert into queries to show that they're low-priority, like
2439          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2440          * string and nothing bad should happen.
2441          *
2442          * @return string Returns the text of the low priority option if it is
2443          *   supported, or a blank string otherwise
2444          */
2445         public function lowPriorityOption() {
2446                 return '';
2447         }
2448
2449         public function delete( $table, $conds, $fname = __METHOD__ ) {
2450                 if ( !$conds ) {
2451                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2452                 }
2453
2454                 $table = $this->tableName( $table );
2455                 $sql = "DELETE FROM $table";
2456
2457                 if ( $conds != '*' ) {
2458                         if ( is_array( $conds ) ) {
2459                                 $conds = $this->makeList( $conds, LIST_AND );
2460                         }
2461                         $sql .= ' WHERE ' . $conds;
2462                 }
2463
2464                 return $this->query( $sql, $fname );
2465         }
2466
2467         public function insertSelect(
2468                 $destTable, $srcTable, $varMap, $conds,
2469                 $fname = __METHOD__, $insertOptions = [], $selectOptions = []
2470         ) {
2471                 if ( $this->cliMode ) {
2472                         // For massive migrations with downtime, we don't want to select everything
2473                         // into memory and OOM, so do all this native on the server side if possible.
2474                         return $this->nativeInsertSelect(
2475                                 $destTable,
2476                                 $srcTable,
2477                                 $varMap,
2478                                 $conds,
2479                                 $fname,
2480                                 $insertOptions,
2481                                 $selectOptions
2482                         );
2483                 }
2484
2485                 // For web requests, do a locking SELECT and then INSERT. This puts the SELECT burden
2486                 // on only the master (without needing row-based-replication). It also makes it easy to
2487                 // know how big the INSERT is going to be.
2488                 $fields = [];
2489                 foreach ( $varMap as $dstColumn => $sourceColumnOrSql ) {
2490                         $fields[] = $this->fieldNameWithAlias( $sourceColumnOrSql, $dstColumn );
2491                 }
2492                 $selectOptions[] = 'FOR UPDATE';
2493                 $res = $this->select( $srcTable, implode( ',', $fields ), $conds, $fname, $selectOptions );
2494                 if ( !$res ) {
2495                         return false;
2496                 }
2497
2498                 $rows = [];
2499                 foreach ( $res as $row ) {
2500                         $rows[] = (array)$row;
2501                 }
2502
2503                 return $this->insert( $destTable, $rows, $fname, $insertOptions );
2504         }
2505
2506         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds,
2507                 $fname = __METHOD__,
2508                 $insertOptions = [], $selectOptions = []
2509         ) {
2510                 $destTable = $this->tableName( $destTable );
2511
2512                 if ( !is_array( $insertOptions ) ) {
2513                         $insertOptions = [ $insertOptions ];
2514                 }
2515
2516                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2517
2518                 if ( !is_array( $selectOptions ) ) {
2519                         $selectOptions = [ $selectOptions ];
2520                 }
2521
2522                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) = $this->makeSelectOptions(
2523                         $selectOptions );
2524
2525                 if ( is_array( $srcTable ) ) {
2526                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
2527                 } else {
2528                         $srcTable = $this->tableName( $srcTable );
2529                 }
2530
2531                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2532                         " SELECT $startOpts " . implode( ',', $varMap ) .
2533                         " FROM $srcTable $useIndex $ignoreIndex ";
2534
2535                 if ( $conds != '*' ) {
2536                         if ( is_array( $conds ) ) {
2537                                 $conds = $this->makeList( $conds, LIST_AND );
2538                         }
2539                         $sql .= " WHERE $conds";
2540                 }
2541
2542                 $sql .= " $tailOpts";
2543
2544                 return $this->query( $sql, $fname );
2545         }
2546
2547         /**
2548          * Construct a LIMIT query with optional offset. This is used for query
2549          * pages. The SQL should be adjusted so that only the first $limit rows
2550          * are returned. If $offset is provided as well, then the first $offset
2551          * rows should be discarded, and the next $limit rows should be returned.
2552          * If the result of the query is not ordered, then the rows to be returned
2553          * are theoretically arbitrary.
2554          *
2555          * $sql is expected to be a SELECT, if that makes a difference.
2556          *
2557          * The version provided by default works in MySQL and SQLite. It will very
2558          * likely need to be overridden for most other DBMSes.
2559          *
2560          * @param string $sql SQL query we will append the limit too
2561          * @param int $limit The SQL limit
2562          * @param int|bool $offset The SQL offset (default false)
2563          * @throws DBUnexpectedError
2564          * @return string
2565          */
2566         public function limitResult( $sql, $limit, $offset = false ) {
2567                 if ( !is_numeric( $limit ) ) {
2568                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2569                 }
2570
2571                 return "$sql LIMIT "
2572                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2573                         . "{$limit} ";
2574         }
2575
2576         public function unionSupportsOrderAndLimit() {
2577                 return true; // True for almost every DB supported
2578         }
2579
2580         public function unionQueries( $sqls, $all ) {
2581                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2582
2583                 return '(' . implode( $glue, $sqls ) . ')';
2584         }
2585
2586         public function conditional( $cond, $trueVal, $falseVal ) {
2587                 if ( is_array( $cond ) ) {
2588                         $cond = $this->makeList( $cond, LIST_AND );
2589                 }
2590
2591                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2592         }
2593
2594         public function strreplace( $orig, $old, $new ) {
2595                 return "REPLACE({$orig}, {$old}, {$new})";
2596         }
2597
2598         public function getServerUptime() {
2599                 return 0;
2600         }
2601
2602         public function wasDeadlock() {
2603                 return false;
2604         }
2605
2606         public function wasLockTimeout() {
2607                 return false;
2608         }
2609
2610         public function wasErrorReissuable() {
2611                 return false;
2612         }
2613
2614         public function wasReadOnlyError() {
2615                 return false;
2616         }
2617
2618         /**
2619          * Determines if the given query error was a connection drop
2620          * STUB
2621          *
2622          * @param integer|string $errno
2623          * @return bool
2624          */
2625         public function wasConnectionError( $errno ) {
2626                 return false;
2627         }
2628
2629         /**
2630          * Perform a deadlock-prone transaction.
2631          *
2632          * This function invokes a callback function to perform a set of write
2633          * queries. If a deadlock occurs during the processing, the transaction
2634          * will be rolled back and the callback function will be called again.
2635          *
2636          * Avoid using this method outside of Job or Maintenance classes.
2637          *
2638          * Usage:
2639          *   $dbw->deadlockLoop( callback, ... );
2640          *
2641          * Extra arguments are passed through to the specified callback function.
2642          * This method requires that no transactions are already active to avoid
2643          * causing premature commits or exceptions.
2644          *
2645          * Returns whatever the callback function returned on its successful,
2646          * iteration, or false on error, for example if the retry limit was
2647          * reached.
2648          *
2649          * @return mixed
2650          * @throws DBUnexpectedError
2651          * @throws Exception
2652          */
2653         public function deadlockLoop() {
2654                 $args = func_get_args();
2655                 $function = array_shift( $args );
2656                 $tries = self::DEADLOCK_TRIES;
2657
2658                 $this->begin( __METHOD__ );
2659
2660                 $retVal = null;
2661                 /** @var Exception $e */
2662                 $e = null;
2663                 do {
2664                         try {
2665                                 $retVal = call_user_func_array( $function, $args );
2666                                 break;
2667                         } catch ( DBQueryError $e ) {
2668                                 if ( $this->wasDeadlock() ) {
2669                                         // Retry after a randomized delay
2670                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2671                                 } else {
2672                                         // Throw the error back up
2673                                         throw $e;
2674                                 }
2675                         }
2676                 } while ( --$tries > 0 );
2677
2678                 if ( $tries <= 0 ) {
2679                         // Too many deadlocks; give up
2680                         $this->rollback( __METHOD__ );
2681                         throw $e;
2682                 } else {
2683                         $this->commit( __METHOD__ );
2684
2685                         return $retVal;
2686                 }
2687         }
2688
2689         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2690                 # Real waits are implemented in the subclass.
2691                 return 0;
2692         }
2693
2694         public function getSlavePos() {
2695                 # Stub
2696                 return false;
2697         }
2698
2699         public function getMasterPos() {
2700                 # Stub
2701                 return false;
2702         }
2703
2704         public function serverIsReadOnly() {
2705                 return false;
2706         }
2707
2708         final public function onTransactionResolution( callable $callback ) {
2709                 if ( !$this->mTrxLevel ) {
2710                         throw new DBUnexpectedError( $this, "No transaction is active." );
2711                 }
2712                 $this->mTrxEndCallbacks[] = [ $callback, wfGetCaller() ];
2713         }
2714
2715         final public function onTransactionIdle( callable $callback ) {
2716                 $this->mTrxIdleCallbacks[] = [ $callback, wfGetCaller() ];
2717                 if ( !$this->mTrxLevel ) {
2718                         $this->runOnTransactionIdleCallbacks( self::TRIGGER_IDLE );
2719                 }
2720         }
2721
2722         final public function onTransactionPreCommitOrIdle( callable $callback ) {
2723                 if ( $this->mTrxLevel ) {
2724                         $this->mTrxPreCommitCallbacks[] = [ $callback, wfGetCaller() ];
2725                 } else {
2726                         // If no transaction is active, then make one for this callback
2727                         $this->startAtomic( __METHOD__ );
2728                         try {
2729                                 call_user_func( $callback );
2730                                 $this->endAtomic( __METHOD__ );
2731                         } catch ( Exception $e ) {
2732                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2733                                 throw $e;
2734                         }
2735                 }
2736         }
2737
2738         final public function setTransactionListener( $name, callable $callback = null ) {
2739                 if ( $callback ) {
2740                         $this->mTrxRecurringCallbacks[$name] = [ $callback, wfGetCaller() ];
2741                 } else {
2742                         unset( $this->mTrxRecurringCallbacks[$name] );
2743                 }
2744         }
2745
2746         /**
2747          * Whether to disable running of post-COMMIT/ROLLBACK callbacks
2748          *
2749          * This method should not be used outside of Database/LoadBalancer
2750          *
2751          * @param bool $suppress
2752          * @since 1.28
2753          */
2754         final public function setTrxEndCallbackSuppression( $suppress ) {
2755                 $this->mTrxEndCallbacksSuppressed = $suppress;
2756         }
2757
2758         /**
2759          * Actually run and consume any "on transaction idle/resolution" callbacks.
2760          *
2761          * This method should not be used outside of Database/LoadBalancer
2762          *
2763          * @param integer $trigger IDatabase::TRIGGER_* constant
2764          * @since 1.20
2765          * @throws Exception
2766          */
2767         public function runOnTransactionIdleCallbacks( $trigger ) {
2768                 if ( $this->mTrxEndCallbacksSuppressed ) {
2769                         return;
2770                 }
2771
2772                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2773                 /** @var Exception $e */
2774                 $e = null; // first exception
2775                 do { // callbacks may add callbacks :)
2776                         $callbacks = array_merge(
2777                                 $this->mTrxIdleCallbacks,
2778                                 $this->mTrxEndCallbacks // include "transaction resolution" callbacks
2779                         );
2780                         $this->mTrxIdleCallbacks = []; // consumed (and recursion guard)
2781                         $this->mTrxEndCallbacks = []; // consumed (recursion guard)
2782                         foreach ( $callbacks as $callback ) {
2783                                 try {
2784                                         list( $phpCallback ) = $callback;
2785                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2786                                         call_user_func_array( $phpCallback, [ $trigger ] );
2787                                         if ( $autoTrx ) {
2788                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2789                                         } else {
2790                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2791                                         }
2792                                 } catch ( Exception $ex ) {
2793                                         MWExceptionHandler::logException( $ex );
2794                                         $e = $e ?: $ex;
2795                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2796                                         // their transactions are ended so other callbacks don't fail
2797                                         if ( $this->trxLevel() ) {
2798                                                 $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
2799                                         }
2800                                 }
2801                         }
2802                 } while ( count( $this->mTrxIdleCallbacks ) );
2803
2804                 if ( $e instanceof Exception ) {
2805                         throw $e; // re-throw any first exception
2806                 }
2807         }
2808
2809         /**
2810          * Actually run and consume any "on transaction pre-commit" callbacks.
2811          *
2812          * This method should not be used outside of Database/LoadBalancer
2813          *
2814          * @since 1.22
2815          * @throws Exception
2816          */
2817         public function runOnTransactionPreCommitCallbacks() {
2818                 $e = null; // first exception
2819                 do { // callbacks may add callbacks :)
2820                         $callbacks = $this->mTrxPreCommitCallbacks;
2821                         $this->mTrxPreCommitCallbacks = []; // consumed (and recursion guard)
2822                         foreach ( $callbacks as $callback ) {
2823                                 try {
2824                                         list( $phpCallback ) = $callback;
2825                                         call_user_func( $phpCallback );
2826                                 } catch ( Exception $ex ) {
2827                                         MWExceptionHandler::logException( $ex );
2828                                         $e = $e ?: $ex;
2829                                 }
2830                         }
2831                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2832
2833                 if ( $e instanceof Exception ) {
2834                         throw $e; // re-throw any first exception
2835                 }
2836         }
2837
2838         /**
2839          * Actually run any "transaction listener" callbacks.
2840          *
2841          * This method should not be used outside of Database/LoadBalancer
2842          *
2843          * @param integer $trigger IDatabase::TRIGGER_* constant
2844          * @throws Exception
2845          * @since 1.20
2846          */
2847         public function runTransactionListenerCallbacks( $trigger ) {
2848                 if ( $this->mTrxEndCallbacksSuppressed ) {
2849                         return;
2850                 }
2851
2852                 /** @var Exception $e */
2853                 $e = null; // first exception
2854
2855                 foreach ( $this->mTrxRecurringCallbacks as $callback ) {
2856                         try {
2857                                 list( $phpCallback ) = $callback;
2858                                 $phpCallback( $trigger, $this );
2859                         } catch ( Exception $ex ) {
2860                                 MWExceptionHandler::logException( $ex );
2861                                 $e = $e ?: $ex;
2862                         }
2863                 }
2864
2865                 if ( $e instanceof Exception ) {
2866                         throw $e; // re-throw any first exception
2867                 }
2868         }
2869
2870         final public function startAtomic( $fname = __METHOD__ ) {
2871                 if ( !$this->mTrxLevel ) {
2872                         $this->begin( $fname, self::TRANSACTION_INTERNAL );
2873                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2874                         // in all changes being in one transaction to keep requests transactional.
2875                         if ( !$this->getFlag( DBO_TRX ) ) {
2876                                 $this->mTrxAutomaticAtomic = true;
2877                         }
2878                 }
2879
2880                 $this->mTrxAtomicLevels[] = $fname;
2881         }
2882
2883         final public function endAtomic( $fname = __METHOD__ ) {
2884                 if ( !$this->mTrxLevel ) {
2885                         throw new DBUnexpectedError( $this, "No atomic transaction is open (got $fname)." );
2886                 }
2887                 if ( !$this->mTrxAtomicLevels ||
2888                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2889                 ) {
2890                         throw new DBUnexpectedError( $this, "Invalid atomic section ended (got $fname)." );
2891                 }
2892
2893                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2894                         $this->commit( $fname, self::FLUSHING_INTERNAL );
2895                 }
2896         }
2897
2898         final public function doAtomicSection( $fname, callable $callback ) {
2899                 $this->startAtomic( $fname );
2900                 try {
2901                         $res = call_user_func_array( $callback, [ $this, $fname ] );
2902                 } catch ( Exception $e ) {
2903                         $this->rollback( $fname, self::FLUSHING_INTERNAL );
2904                         throw $e;
2905                 }
2906                 $this->endAtomic( $fname );
2907
2908                 return $res;
2909         }
2910
2911         final public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT ) {
2912                 // Protect against mismatched atomic section, transaction nesting, and snapshot loss
2913                 if ( $this->mTrxLevel ) {
2914                         if ( $this->mTrxAtomicLevels ) {
2915                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2916                                 $msg = "$fname: Got explicit BEGIN while atomic section(s) $levels are open.";
2917                                 throw new DBUnexpectedError( $this, $msg );
2918                         } elseif ( !$this->mTrxAutomatic ) {
2919                                 $msg = "$fname: Explicit transaction already active (from {$this->mTrxFname}).";
2920                                 throw new DBUnexpectedError( $this, $msg );
2921                         } else {
2922                                 // @TODO: make this an exception at some point
2923                                 $msg = "$fname: Implicit transaction already active (from {$this->mTrxFname}).";
2924                                 wfLogDBError( $msg );
2925                                 wfWarn( $msg );
2926                                 return; // join the main transaction set
2927                         }
2928                 } elseif ( $this->getFlag( DBO_TRX ) && $mode !== self::TRANSACTION_INTERNAL ) {
2929                         // @TODO: make this an exception at some point
2930                         $msg = "$fname: Implicit transaction expected (DBO_TRX set).";
2931                         wfLogDBError( $msg );
2932                         wfWarn( $msg );
2933                         return; // let any writes be in the main transaction
2934                 }
2935
2936                 // Avoid fatals if close() was called
2937                 $this->assertOpen();
2938
2939                 $this->doBegin( $fname );
2940                 $this->mTrxTimestamp = microtime( true );
2941                 $this->mTrxFname = $fname;
2942                 $this->mTrxDoneWrites = false;
2943                 $this->mTrxAutomatic = ( $mode === self::TRANSACTION_INTERNAL );
2944                 $this->mTrxAutomaticAtomic = false;
2945                 $this->mTrxAtomicLevels = [];
2946                 $this->mTrxShortId = wfRandomString( 12 );
2947                 $this->mTrxWriteDuration = 0.0;
2948                 $this->mTrxWriteQueryCount = 0;
2949                 $this->mTrxWriteAdjDuration = 0.0;
2950                 $this->mTrxWriteAdjQueryCount = 0;
2951                 $this->mTrxWriteCallers = [];
2952                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2953                 // Get an estimate of the replica DB lag before then, treating estimate staleness
2954                 // as lag itself just to be safe
2955                 $status = $this->getApproximateLagStatus();
2956                 $this->mTrxReplicaLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2957         }
2958
2959         /**
2960          * Issues the BEGIN command to the database server.
2961          *
2962          * @see DatabaseBase::begin()
2963          * @param string $fname
2964          */
2965         protected function doBegin( $fname ) {
2966                 $this->query( 'BEGIN', $fname );
2967                 $this->mTrxLevel = 1;
2968         }
2969
2970         final public function commit( $fname = __METHOD__, $flush = '' ) {
2971                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2972                         // There are still atomic sections open. This cannot be ignored
2973                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2974                         throw new DBUnexpectedError(
2975                                 $this,
2976                                 "$fname: Got COMMIT while atomic sections $levels are still open."
2977                         );
2978                 }
2979
2980                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
2981                         if ( !$this->mTrxLevel ) {
2982                                 return; // nothing to do
2983                         } elseif ( !$this->mTrxAutomatic ) {
2984                                 throw new DBUnexpectedError(
2985                                         $this,
2986                                         "$fname: Flushing an explicit transaction, getting out of sync."
2987                                 );
2988                         }
2989                 } else {
2990                         if ( !$this->mTrxLevel ) {
2991                                 wfWarn( "$fname: No transaction to commit, something got out of sync." );
2992                                 return; // nothing to do
2993                         } elseif ( $this->mTrxAutomatic ) {
2994                                 // @TODO: make this an exception at some point
2995                                 $msg = "$fname: Explicit commit of implicit transaction.";
2996                                 wfLogDBError( $msg );
2997                                 wfWarn( $msg );
2998                                 return; // wait for the main transaction set commit round
2999                         }
3000                 }
3001
3002                 // Avoid fatals if close() was called
3003                 $this->assertOpen();
3004
3005                 $this->runOnTransactionPreCommitCallbacks();
3006                 $writeTime = $this->pendingWriteQueryDuration( self::ESTIMATE_DB_APPLY );
3007                 $this->doCommit( $fname );
3008                 if ( $this->mTrxDoneWrites ) {
3009                         $this->mDoneWrites = microtime( true );
3010                         $this->trxProfiler->transactionWritingOut(
3011                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
3012                 }
3013
3014                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_COMMIT );
3015                 $this->runTransactionListenerCallbacks( self::TRIGGER_COMMIT );
3016         }
3017
3018         /**
3019          * Issues the COMMIT command to the database server.
3020          *
3021          * @see DatabaseBase::commit()
3022          * @param string $fname
3023          */
3024         protected function doCommit( $fname ) {
3025                 if ( $this->mTrxLevel ) {
3026                         $this->query( 'COMMIT', $fname );
3027                         $this->mTrxLevel = 0;
3028                 }
3029         }
3030
3031         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3032                 if ( $flush === self::FLUSHING_INTERNAL || $flush === self::FLUSHING_ALL_PEERS ) {
3033                         if ( !$this->mTrxLevel ) {
3034                                 return; // nothing to do
3035                         }
3036                 } else {
3037                         if ( !$this->mTrxLevel ) {
3038                                 wfWarn( "$fname: No transaction to rollback, something got out of sync." );
3039                                 return; // nothing to do
3040                         } elseif ( $this->getFlag( DBO_TRX ) ) {
3041                                 throw new DBUnexpectedError(
3042                                         $this,
3043                                         "$fname: Expected mass rollback of all peer databases (DBO_TRX set)."
3044                                 );
3045                         }
3046                 }
3047
3048                 // Avoid fatals if close() was called
3049                 $this->assertOpen();
3050
3051                 $this->doRollback( $fname );
3052                 $this->mTrxAtomicLevels = [];
3053                 if ( $this->mTrxDoneWrites ) {
3054                         $this->trxProfiler->transactionWritingOut(
3055                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3056                 }
3057
3058                 $this->mTrxIdleCallbacks = []; // clear
3059                 $this->mTrxPreCommitCallbacks = []; // clear
3060                 $this->runOnTransactionIdleCallbacks( self::TRIGGER_ROLLBACK );
3061                 $this->runTransactionListenerCallbacks( self::TRIGGER_ROLLBACK );
3062         }
3063
3064         /**
3065          * Issues the ROLLBACK command to the database server.
3066          *
3067          * @see DatabaseBase::rollback()
3068          * @param string $fname
3069          */
3070         protected function doRollback( $fname ) {
3071                 if ( $this->mTrxLevel ) {
3072                         # Disconnects cause rollback anyway, so ignore those errors
3073                         $ignoreErrors = true;
3074                         $this->query( 'ROLLBACK', $fname, $ignoreErrors );
3075                         $this->mTrxLevel = 0;
3076                 }
3077         }
3078
3079         public function flushSnapshot( $fname = __METHOD__ ) {
3080                 if ( $this->writesOrCallbacksPending() || $this->explicitTrxActive() ) {
3081                         // This only flushes transactions to clear snapshots, not to write data
3082                         throw new DBUnexpectedError(
3083                                 $this,
3084                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3085                         );
3086                 }
3087
3088                 $this->commit( $fname, self::FLUSHING_INTERNAL );
3089         }
3090
3091         public function explicitTrxActive() {
3092                 return $this->mTrxLevel && ( $this->mTrxAtomicLevels || !$this->mTrxAutomatic );
3093         }
3094
3095         /**
3096          * Creates a new table with structure copied from existing table
3097          * Note that unlike most database abstraction functions, this function does not
3098          * automatically append database prefix, because it works at a lower
3099          * abstraction level.
3100          * The table names passed to this function shall not be quoted (this
3101          * function calls addIdentifierQuotes when needed).
3102          *
3103          * @param string $oldName Name of table whose structure should be copied
3104          * @param string $newName Name of table to be created
3105          * @param bool $temporary Whether the new table should be temporary
3106          * @param string $fname Calling function name
3107          * @throws MWException
3108          * @return bool True if operation was successful
3109          */
3110         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3111                 $fname = __METHOD__
3112         ) {
3113                 throw new MWException(
3114                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3115         }
3116
3117         function listTables( $prefix = null, $fname = __METHOD__ ) {
3118                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3119         }
3120
3121         /**
3122          * Reset the views process cache set by listViews()
3123          * @since 1.22
3124          */
3125         final public function clearViewsCache() {
3126                 $this->allViews = null;
3127         }
3128
3129         /**
3130          * Lists all the VIEWs in the database
3131          *
3132          * For caching purposes the list of all views should be stored in
3133          * $this->allViews. The process cache can be cleared with clearViewsCache()
3134          *
3135          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3136          * @param string $fname Name of calling function
3137          * @throws MWException
3138          * @return array
3139          * @since 1.22
3140          */
3141         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3142                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
3143         }
3144
3145         /**
3146          * Differentiates between a TABLE and a VIEW
3147          *
3148          * @param string $name Name of the database-structure to test.
3149          * @throws MWException
3150          * @return bool
3151          * @since 1.22
3152          */
3153         public function isView( $name ) {
3154                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
3155         }
3156
3157         public function timestamp( $ts = 0 ) {
3158                 return wfTimestamp( TS_MW, $ts );
3159         }
3160
3161         public function timestampOrNull( $ts = null ) {
3162                 if ( is_null( $ts ) ) {
3163                         return null;
3164                 } else {
3165                         return $this->timestamp( $ts );
3166                 }
3167         }
3168
3169         /**
3170          * Take the result from a query, and wrap it in a ResultWrapper if
3171          * necessary. Boolean values are passed through as is, to indicate success
3172          * of write queries or failure.
3173          *
3174          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3175          * resource, and it was necessary to call this function to convert it to
3176          * a wrapper. Nowadays, raw database objects are never exposed to external
3177          * callers, so this is unnecessary in external code.
3178          *
3179          * @param bool|ResultWrapper|resource|object $result
3180          * @return bool|ResultWrapper
3181          */
3182         protected function resultObject( $result ) {
3183                 if ( !$result ) {
3184                         return false;
3185                 } elseif ( $result instanceof ResultWrapper ) {
3186                         return $result;
3187                 } elseif ( $result === true ) {
3188                         // Successful write query
3189                         return $result;
3190                 } else {
3191                         return new ResultWrapper( $this, $result );
3192                 }
3193         }
3194
3195         public function ping( &$rtt = null ) {
3196                 // Avoid hitting the server if it was hit recently
3197                 if ( $this->isOpen() && ( microtime( true ) - $this->lastPing ) < self::PING_TTL ) {
3198                         if ( !func_num_args() || $this->mRTTEstimate > 0 ) {
3199                                 $rtt = $this->mRTTEstimate;
3200                                 return true; // don't care about $rtt
3201                         }
3202                 }
3203
3204                 // This will reconnect if possible or return false if not
3205                 $this->clearFlag( DBO_TRX, self::REMEMBER_PRIOR );
3206                 $ok = ( $this->query( self::PING_QUERY, __METHOD__, true ) !== false );
3207                 $this->restoreFlags( self::RESTORE_PRIOR );
3208
3209                 if ( $ok ) {
3210                         $rtt = $this->mRTTEstimate;
3211                 }
3212
3213                 return $ok;
3214         }
3215
3216         /**
3217          * @return bool
3218          */
3219         protected function reconnect() {
3220                 $this->closeConnection();
3221                 $this->mOpened = false;
3222                 $this->mConn = false;
3223                 try {
3224                         $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
3225                         $this->lastPing = microtime( true );
3226                         $ok = true;
3227                 } catch ( DBConnectionError $e ) {
3228                         $ok = false;
3229                 }
3230
3231                 return $ok;
3232         }
3233
3234         public function getSessionLagStatus() {
3235                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
3236         }
3237
3238         /**
3239          * Get the replica DB lag when the current transaction started
3240          *
3241          * This is useful when transactions might use snapshot isolation
3242          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
3243          * is this lag plus transaction duration. If they don't, it is still
3244          * safe to be pessimistic. This returns null if there is no transaction.
3245          *
3246          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
3247          * @since 1.27
3248          */
3249         public function getTransactionLagStatus() {
3250                 return $this->mTrxLevel
3251                         ? [ 'lag' => $this->mTrxReplicaLag, 'since' => $this->trxTimestamp() ]
3252                         : null;
3253         }
3254
3255         /**
3256          * Get a replica DB lag estimate for this server
3257          *
3258          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
3259          * @since 1.27
3260          */
3261         public function getApproximateLagStatus() {
3262                 return [
3263                         'lag'   => $this->getLBInfo( 'replica' ) ? $this->getLag() : 0,
3264                         'since' => microtime( true )
3265                 ];
3266         }
3267
3268         /**
3269          * Merge the result of getSessionLagStatus() for several DBs
3270          * using the most pessimistic values to estimate the lag of
3271          * any data derived from them in combination
3272          *
3273          * This is information is useful for caching modules
3274          *
3275          * @see WANObjectCache::set()
3276          * @see WANObjectCache::getWithSetCallback()
3277          *
3278          * @param IDatabase $db1
3279          * @param IDatabase ...
3280          * @return array Map of values:
3281          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
3282          *   - since: oldest UNIX timestamp of any of the DB lag estimates
3283          *   - pending: whether any of the DBs have uncommitted changes
3284          * @since 1.27
3285          */
3286         public static function getCacheSetOptions( IDatabase $db1 ) {
3287                 $res = [ 'lag' => 0, 'since' => INF, 'pending' => false ];
3288                 foreach ( func_get_args() as $db ) {
3289                         /** @var IDatabase $db */
3290                         $status = $db->getSessionLagStatus();
3291                         if ( $status['lag'] === false ) {
3292                                 $res['lag'] = false;
3293                         } elseif ( $res['lag'] !== false ) {
3294                                 $res['lag'] = max( $res['lag'], $status['lag'] );
3295                         }
3296                         $res['since'] = min( $res['since'], $status['since'] );
3297                         $res['pending'] = $res['pending'] ?: $db->writesPending();
3298                 }
3299
3300                 return $res;
3301         }
3302
3303         public function getLag() {
3304                 return 0;
3305         }
3306
3307         function maxListLen() {
3308                 return 0;
3309         }
3310
3311         public function encodeBlob( $b ) {
3312                 return $b;
3313         }
3314
3315         public function decodeBlob( $b ) {
3316                 if ( $b instanceof Blob ) {
3317                         $b = $b->fetch();
3318                 }
3319                 return $b;
3320         }
3321
3322         public function setSessionOptions( array $options ) {
3323         }
3324
3325         /**
3326          * Read and execute SQL commands from a file.
3327          *
3328          * Returns true on success, error string or exception on failure (depending
3329          * on object's error ignore settings).
3330          *
3331          * @param string $filename File name to open
3332          * @param bool|callable $lineCallback Optional function called before reading each line
3333          * @param bool|callable $resultCallback Optional function called for each MySQL result
3334          * @param bool|string $fname Calling function name or false if name should be
3335          *   generated dynamically using $filename
3336          * @param bool|callable $inputCallback Optional function called for each
3337          *   complete line sent
3338          * @throws Exception|MWException
3339          * @return bool|string
3340          */
3341         public function sourceFile(
3342                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3343         ) {
3344                 MediaWiki\suppressWarnings();
3345                 $fp = fopen( $filename, 'r' );
3346                 MediaWiki\restoreWarnings();
3347
3348                 if ( false === $fp ) {
3349                         throw new MWException( "Could not open \"{$filename}\".\n" );
3350                 }
3351
3352                 if ( !$fname ) {
3353                         $fname = __METHOD__ . "( $filename )";
3354                 }
3355
3356                 try {
3357                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3358                 } catch ( Exception $e ) {
3359                         fclose( $fp );
3360                         throw $e;
3361                 }
3362
3363                 fclose( $fp );
3364
3365                 return $error;
3366         }
3367
3368         /**
3369          * Get the full path of a patch file. Originally based on archive()
3370          * from updaters.inc. Keep in mind this always returns a patch, as
3371          * it fails back to MySQL if no DB-specific patch can be found
3372          *
3373          * @param string $patch The name of the patch, like patch-something.sql
3374          * @return string Full path to patch file
3375          */
3376         public function patchPath( $patch ) {
3377                 global $IP;
3378
3379                 $dbType = $this->getType();
3380                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3381                         return "$IP/maintenance/$dbType/archives/$patch";
3382                 } else {
3383                         return "$IP/maintenance/archives/$patch";
3384                 }
3385         }
3386
3387         public function setSchemaVars( $vars ) {
3388                 $this->mSchemaVars = $vars;
3389         }
3390
3391         /**
3392          * Read and execute commands from an open file handle.
3393          *
3394          * Returns true on success, error string or exception on failure (depending
3395          * on object's error ignore settings).
3396          *
3397          * @param resource $fp File handle
3398          * @param bool|callable $lineCallback Optional function called before reading each query
3399          * @param bool|callable $resultCallback Optional function called for each MySQL result
3400          * @param string $fname Calling function name
3401          * @param bool|callable $inputCallback Optional function called for each complete query sent
3402          * @return bool|string
3403          */
3404         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3405                 $fname = __METHOD__, $inputCallback = false
3406         ) {
3407                 $cmd = '';
3408
3409                 while ( !feof( $fp ) ) {
3410                         if ( $lineCallback ) {
3411                                 call_user_func( $lineCallback );
3412                         }
3413
3414                         $line = trim( fgets( $fp ) );
3415
3416                         if ( $line == '' ) {
3417                                 continue;
3418                         }
3419
3420                         if ( '-' == $line[0] && '-' == $line[1] ) {
3421                                 continue;
3422                         }
3423
3424                         if ( $cmd != '' ) {
3425                                 $cmd .= ' ';
3426                         }
3427
3428                         $done = $this->streamStatementEnd( $cmd, $line );
3429
3430                         $cmd .= "$line\n";
3431
3432                         if ( $done || feof( $fp ) ) {
3433                                 $cmd = $this->replaceVars( $cmd );
3434
3435                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3436                                         $res = $this->query( $cmd, $fname );
3437
3438                                         if ( $resultCallback ) {
3439                                                 call_user_func( $resultCallback, $res, $this );
3440                                         }
3441
3442                                         if ( false === $res ) {
3443                                                 $err = $this->lastError();
3444
3445                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3446                                         }
3447                                 }
3448                                 $cmd = '';
3449                         }
3450                 }
3451
3452                 return true;
3453         }
3454
3455         /**
3456          * Called by sourceStream() to check if we've reached a statement end
3457          *
3458          * @param string $sql SQL assembled so far
3459          * @param string $newLine New line about to be added to $sql
3460          * @return bool Whether $newLine contains end of the statement
3461          */
3462         public function streamStatementEnd( &$sql, &$newLine ) {
3463                 if ( $this->delimiter ) {
3464                         $prev = $newLine;
3465                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3466                         if ( $newLine != $prev ) {
3467                                 return true;
3468                         }
3469                 }
3470
3471                 return false;
3472         }
3473
3474         /**
3475          * Database independent variable replacement. Replaces a set of variables
3476          * in an SQL statement with their contents as given by $this->getSchemaVars().
3477          *
3478          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3479          *
3480          * - '{$var}' should be used for text and is passed through the database's
3481          *   addQuotes method.
3482          * - `{$var}` should be used for identifiers (e.g. table and database names).
3483          *   It is passed through the database's addIdentifierQuotes method which
3484          *   can be overridden if the database uses something other than backticks.
3485          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3486          *   database's tableName method.
3487          * - / *i* / passes the name that follows through the database's indexName method.
3488          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3489          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3490          *
3491          * @param string $ins SQL statement to replace variables in
3492          * @return string The new SQL statement with variables replaced
3493          */
3494         protected function replaceVars( $ins ) {
3495                 $vars = $this->getSchemaVars();
3496                 return preg_replace_callback(
3497                         '!
3498                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3499                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3500                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3501                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3502                         !x',
3503                         function ( $m ) use ( $vars ) {
3504                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3505                                 // check for both nonexistent keys *and* the empty string.
3506                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3507                                         if ( $m[1] === 'i' ) {
3508                                                 return $this->indexName( $m[2] );
3509                                         } else {
3510                                                 return $this->tableName( $m[2] );
3511                                         }
3512                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3513                                         return $this->addQuotes( $vars[$m[3]] );
3514                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3515                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3516                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3517                                         return $vars[$m[5]];
3518                                 } else {
3519                                         return $m[0];
3520                                 }
3521                         },
3522                         $ins
3523                 );
3524         }
3525
3526         /**
3527          * Get schema variables. If none have been set via setSchemaVars(), then
3528          * use some defaults from the current object.
3529          *
3530          * @return array
3531          */
3532         protected function getSchemaVars() {
3533                 if ( $this->mSchemaVars ) {
3534                         return $this->mSchemaVars;
3535                 } else {
3536                         return $this->getDefaultSchemaVars();
3537                 }
3538         }
3539
3540         /**
3541          * Get schema variables to use if none have been set via setSchemaVars().
3542          *
3543          * Override this in derived classes to provide variables for tables.sql
3544          * and SQL patch files.
3545          *
3546          * @return array
3547          */
3548         protected function getDefaultSchemaVars() {
3549                 return [];
3550         }
3551
3552         public function lockIsFree( $lockName, $method ) {
3553                 return true;
3554         }
3555
3556         public function lock( $lockName, $method, $timeout = 5 ) {
3557                 $this->mNamedLocksHeld[$lockName] = 1;
3558
3559                 return true;
3560         }
3561
3562         public function unlock( $lockName, $method ) {
3563                 unset( $this->mNamedLocksHeld[$lockName] );
3564
3565                 return true;
3566         }
3567
3568         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3569                 if ( $this->writesOrCallbacksPending() ) {
3570                         // This only flushes transactions to clear snapshots, not to write data
3571                         throw new DBUnexpectedError(
3572                                 $this,
3573                                 "$fname: Cannot COMMIT to clear snapshot because writes are pending."
3574                         );
3575                 }
3576
3577                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3578                         return null;
3579                 }
3580
3581                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3582                         if ( $this->trxLevel() ) {
3583                                 // There is a good chance an exception was thrown, causing any early return
3584                                 // from the caller. Let any error handler get a chance to issue rollback().
3585                                 // If there isn't one, let the error bubble up and trigger server-side rollback.
3586                                 $this->onTransactionResolution( function () use ( $lockKey, $fname ) {
3587                                         $this->unlock( $lockKey, $fname );
3588                                 } );
3589                         } else {
3590                                 $this->unlock( $lockKey, $fname );
3591                         }
3592                 } );
3593
3594                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
3595
3596                 return $unlocker;
3597         }
3598
3599         public function namedLocksEnqueue() {
3600                 return false;
3601         }
3602
3603         /**
3604          * Lock specific tables
3605          *
3606          * @param array $read Array of tables to lock for read access
3607          * @param array $write Array of tables to lock for write access
3608          * @param string $method Name of caller
3609          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3610          * @return bool
3611          */
3612         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3613                 return true;
3614         }
3615
3616         /**
3617          * Unlock specific tables
3618          *
3619          * @param string $method The caller
3620          * @return bool
3621          */
3622         public function unlockTables( $method ) {
3623                 return true;
3624         }
3625
3626         /**
3627          * Delete a table
3628          * @param string $tableName
3629          * @param string $fName
3630          * @return bool|ResultWrapper
3631          * @since 1.18
3632          */
3633         public function dropTable( $tableName, $fName = __METHOD__ ) {
3634                 if ( !$this->tableExists( $tableName, $fName ) ) {
3635                         return false;
3636                 }
3637                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3638                 if ( $this->cascadingDeletes() ) {
3639                         $sql .= " CASCADE";
3640                 }
3641
3642                 return $this->query( $sql, $fName );
3643         }
3644
3645         /**
3646          * Get search engine class. All subclasses of this need to implement this
3647          * if they wish to use searching.
3648          *
3649          * @return string
3650          */
3651         public function getSearchEngine() {
3652                 return 'SearchEngineDummy';
3653         }
3654
3655         public function getInfinity() {
3656                 return 'infinity';
3657         }
3658
3659         public function encodeExpiry( $expiry ) {
3660                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3661                         ? $this->getInfinity()
3662                         : $this->timestamp( $expiry );
3663         }
3664
3665         public function decodeExpiry( $expiry, $format = TS_MW ) {
3666                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3667                         ? 'infinity'
3668                         : wfTimestamp( $format, $expiry );
3669         }
3670
3671         public function setBigSelects( $value = true ) {
3672                 // no-op
3673         }
3674
3675         public function isReadOnly() {
3676                 return ( $this->getReadOnlyReason() !== false );
3677         }
3678
3679         /**
3680          * @return string|bool Reason this DB is read-only or false if it is not
3681          */
3682         protected function getReadOnlyReason() {
3683                 $reason = $this->getLBInfo( 'readOnlyReason' );
3684
3685                 return is_string( $reason ) ? $reason : false;
3686         }
3687
3688         /**
3689          * @since 1.19
3690          * @return string
3691          */
3692         public function __toString() {
3693                 return (string)$this->mConn;
3694         }
3695
3696         /**
3697          * Run a few simple sanity checks
3698          */
3699         public function __destruct() {
3700                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3701                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3702                 }
3703                 $danglingCallbacks = array_merge(
3704                         $this->mTrxIdleCallbacks,
3705                         $this->mTrxPreCommitCallbacks,
3706                         $this->mTrxEndCallbacks
3707                 );
3708                 if ( $danglingCallbacks ) {
3709                         $callers = [];
3710                         foreach ( $danglingCallbacks as $callbackInfo ) {
3711                                 $callers[] = $callbackInfo[1];
3712                         }
3713                         $callers = implode( ', ', $callers );
3714                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3715                 }
3716         }
3717 }
3718
3719 /**
3720  * @since 1.27
3721  */
3722 abstract class Database extends DatabaseBase {
3723         // B/C until nothing type hints for DatabaseBase
3724         // @TODO: finish renaming DatabaseBase => Database
3725 }