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
  36         /** Minimum time to wait before retry, in microseconds */
  37         const DEADLOCK_DELAY_MIN = 500000;
  38
  39         /** Maximum time to wait before retry */
  40         const DEADLOCK_DELAY_MAX = 1500000;
  41
  42         protected $mLastQuery = '';
  43         protected $mDoneWrites = false;
  44         protected $mPHPError = false;
  45
  46         protected $mServer, $mUser, $mPassword, $mDBname;
  47
  48         /** @var BagOStuff APC cache */
  49         protected $srvCache;
  50
  51         /** @var resource Database connection */
  52         protected $mConn = null;
  53         protected $mOpened = false;
  54
  55         /** @var callable[] */
  56         protected $mTrxIdleCallbacks = array();
  57         /** @var callable[] */
  58         protected $mTrxPreCommitCallbacks = array();
  59
  60         protected $mTablePrefix;
  61         protected $mSchema;
  62         protected $mFlags;
  63         protected $mForeign;
  64         protected $mLBInfo = array();
  65         protected $mDefaultBigSelects = null;
  66         protected $mSchemaVars = false;
  67         /** @var array */
  68         protected $mSessionVars = array();
  69
  70         protected $preparedArgs;
  71
  72         protected $htmlErrors;
  73
  74         protected $delimiter = ';';
  75
  76         /**
  77          * Either 1 if a transaction is active or 0 otherwise.
  78          * The other Trx fields may not be meaningfull if this is 0.
  79          *
  80          * @var int
  81          */
  82         protected $mTrxLevel = 0;
  83
  84         /**
  85          * Either a short hexidecimal string if a transaction is active or ""
  86          *
  87          * @var string
  88          * @see DatabaseBase::mTrxLevel
  89          */
  90         protected $mTrxShortId = '';
  91
  92         /**
  93          * The UNIX time that the transaction started. Callers can assume that if
  94          * snapshot isolation is used, then the data is *at least* up to date to that
  95          * point (possibly more up-to-date since the first SELECT defines the snapshot).
  96          *
  97          * @var float|null
  98          * @see DatabaseBase::mTrxLevel
  99          */
 100         private $mTrxTimestamp = null;
 101
 102         /** @var float Lag estimate at the time of BEGIN */
 103         private $mTrxSlaveLag = null;
 104
 105         /**
 106          * Remembers the function name given for starting the most recent transaction via begin().
 107          * Used to provide additional context for error reporting.
 108          *
 109          * @var string
 110          * @see DatabaseBase::mTrxLevel
 111          */
 112         private $mTrxFname = null;
 113
 114         /**
 115          * Record if possible write queries were done in the last transaction started
 116          *
 117          * @var bool
 118          * @see DatabaseBase::mTrxLevel
 119          */
 120         private $mTrxDoneWrites = false;
 121
 122         /**
 123          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 124          *
 125          * @var bool
 126          * @see DatabaseBase::mTrxLevel
 127          */
 128         private $mTrxAutomatic = false;
 129
 130         /**
 131          * Array of levels of atomicity within transactions
 132          *
 133          * @var array
 134          */
 135         private $mTrxAtomicLevels = array();
 136
 137         /**
 138          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 139          *
 140          * @var bool
 141          */
 142         private $mTrxAutomaticAtomic = false;
 143
 144         /**
 145          * Track the write query callers of the current transaction
 146          *
 147          * @var string[]
 148          */
 149         private $mTrxWriteCallers = array();
 150
 151         /**
 152          * Track the seconds spent in write queries for the current transaction
 153          *
 154          * @var float
 155          */
 156         private $mTrxWriteDuration = 0.0;
 157
 158         /** @var array Map of (name => 1) for locks obtained via lock() */
 159         private $mNamedLocksHeld = array();
 160
 161         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 162         private $lazyMasterHandle;
 163
 164         /**
 165          * @since 1.21
 166          * @var resource File handle for upgrade
 167          */
 168         protected $fileHandle = null;
 169
 170         /**
 171          * @since 1.22
 172          * @var string[] Process cache of VIEWs names in the database
 173          */
 174         protected $allViews = null;
 175
 176         /** @var TransactionProfiler */
 177         protected $trxProfiler;
 178
 179         public function getServerInfo() {
 180                 return $this->getServerVersion();
 181         }
 182
 183         /**
 184          * @return string Command delimiter used by this database engine
 185          */
 186         public function getDelimiter() {
 187                 return $this->delimiter;
 188         }
 189
 190         /**
 191          * Boolean, controls output of large amounts of debug information.
 192          * @param bool|null $debug
 193          *   - true to enable debugging
 194          *   - false to disable debugging
 195          *   - omitted or null to do nothing
 196          *
 197          * @return bool|null Previous value of the flag
 198          */
 199         public function debug( $debug = null ) {
 200                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 201         }
 202
 203         public function bufferResults( $buffer = null ) {
 204                 if ( is_null( $buffer ) ) {
 205                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 206                 } else {
 207                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 208                 }
 209         }
 210
 211         /**
 212          * Turns on (false) or off (true) the automatic generation and sending
 213          * of a "we're sorry, but there has been a database error" page on
 214          * database errors. Default is on (false). When turned off, the
 215          * code should use lastErrno() and lastError() to handle the
 216          * situation as appropriate.
 217          *
 218          * Do not use this function outside of the Database classes.
 219          *
 220          * @param null|bool $ignoreErrors
 221          * @return bool The previous value of the flag.
 222          */
 223         protected function ignoreErrors( $ignoreErrors = null ) {
 224                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 225         }
 226
 227         public function trxLevel() {
 228                 return $this->mTrxLevel;
 229         }
 230
 231         public function trxTimestamp() {
 232                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 233         }
 234
 235         public function tablePrefix( $prefix = null ) {
 236                 return wfSetVar( $this->mTablePrefix, $prefix );
 237         }
 238
 239         public function dbSchema( $schema = null ) {
 240                 return wfSetVar( $this->mSchema, $schema );
 241         }
 242
 243         /**
 244          * Set the filehandle to copy write statements to.
 245          *
 246          * @param resource $fh File handle
 247          */
 248         public function setFileHandle( $fh ) {
 249                 $this->fileHandle = $fh;
 250         }
 251
 252         public function getLBInfo( $name = null ) {
 253                 if ( is_null( $name ) ) {
 254                         return $this->mLBInfo;
 255                 } else {
 256                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 257                                 return $this->mLBInfo[$name];
 258                         } else {
 259                                 return null;
 260                         }
 261                 }
 262         }
 263
 264         public function setLBInfo( $name, $value = null ) {
 265                 if ( is_null( $value ) ) {
 266                         $this->mLBInfo = $name;
 267                 } else {
 268                         $this->mLBInfo[$name] = $value;
 269                 }
 270         }
 271
 272         /**
 273          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 274          *
 275          * @param IDatabase $conn
 276          * @since 1.27
 277          */
 278         public function setLazyMasterHandle( IDatabase $conn ) {
 279                 $this->lazyMasterHandle = $conn;
 280         }
 281
 282         /**
 283          * @return IDatabase|null
 284          * @see setLazyMasterHandle()
 285          * @since 1.27
 286          */
 287         public function getLazyMasterHandle() {
 288                 return $this->lazyMasterHandle;
 289         }
 290
 291         /**
 292          * @return TransactionProfiler
 293          */
 294         protected function getTransactionProfiler() {
 295                 if ( !$this->trxProfiler ) {
 296                         $this->trxProfiler = new TransactionProfiler();
 297                 }
 298
 299                 return $this->trxProfiler;
 300         }
 301
 302         /**
 303          * @param TransactionProfiler $profiler
 304          * @since 1.27
 305          */
 306         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 307                 $this->trxProfiler = $profiler;
 308         }
 309
 310         /**
 311          * Returns true if this database supports (and uses) cascading deletes
 312          *
 313          * @return bool
 314          */
 315         public function cascadingDeletes() {
 316                 return false;
 317         }
 318
 319         /**
 320          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 321          *
 322          * @return bool
 323          */
 324         public function cleanupTriggers() {
 325                 return false;
 326         }
 327
 328         /**
 329          * Returns true if this database is strict about what can be put into an IP field.
 330          * Specifically, it uses a NULL value instead of an empty string.
 331          *
 332          * @return bool
 333          */
 334         public function strictIPs() {
 335                 return false;
 336         }
 337
 338         /**
 339          * Returns true if this database uses timestamps rather than integers
 340          *
 341          * @return bool
 342          */
 343         public function realTimestamps() {
 344                 return false;
 345         }
 346
 347         public function implicitGroupby() {
 348                 return true;
 349         }
 350
 351         public function implicitOrderby() {
 352                 return true;
 353         }
 354
 355         /**
 356          * Returns true if this database can do a native search on IP columns
 357          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 358          *
 359          * @return bool
 360          */
 361         public function searchableIPs() {
 362                 return false;
 363         }
 364
 365         /**
 366          * Returns true if this database can use functional indexes
 367          *
 368          * @return bool
 369          */
 370         public function functionalIndexes() {
 371                 return false;
 372         }
 373
 374         public function lastQuery() {
 375                 return $this->mLastQuery;
 376         }
 377
 378         public function doneWrites() {
 379                 return (bool)$this->mDoneWrites;
 380         }
 381
 382         public function lastDoneWrites() {
 383                 return $this->mDoneWrites ?: false;
 384         }
 385
 386         public function writesPending() {
 387                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 388         }
 389
 390         public function writesOrCallbacksPending() {
 391                 return $this->mTrxLevel && (
 392                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 393                 );
 394         }
 395
 396         public function pendingWriteQueryDuration() {
 397                 return $this->mTrxLevel ? $this->mTrxWriteDuration : false;
 398         }
 399
 400         public function pendingWriteCallers() {
 401                 return $this->mTrxLevel ? $this->mTrxWriteCallers : array();
 402         }
 403
 404         public function isOpen() {
 405                 return $this->mOpened;
 406         }
 407
 408         public function setFlag( $flag ) {
 409                 $this->mFlags |= $flag;
 410         }
 411
 412         public function clearFlag( $flag ) {
 413                 $this->mFlags &= ~$flag;
 414         }
 415
 416         public function getFlag( $flag ) {
 417                 return !!( $this->mFlags & $flag );
 418         }
 419
 420         public function getProperty( $name ) {
 421                 return $this->$name;
 422         }
 423
 424         public function getWikiID() {
 425                 if ( $this->mTablePrefix ) {
 426                         return "{$this->mDBname}-{$this->mTablePrefix}";
 427                 } else {
 428                         return $this->mDBname;
 429                 }
 430         }
 431
 432         /**
 433          * Return a path to the DBMS-specific SQL file if it exists,
 434          * otherwise default SQL file
 435          *
 436          * @param string $filename
 437          * @return string
 438          */
 439         private function getSqlFilePath( $filename ) {
 440                 global $IP;
 441                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 442                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 443                         return $dbmsSpecificFilePath;
 444                 } else {
 445                         return "$IP/maintenance/$filename";
 446                 }
 447         }
 448
 449         /**
 450          * Return a path to the DBMS-specific schema file,
 451          * otherwise default to tables.sql
 452          *
 453          * @return string
 454          */
 455         public function getSchemaPath() {
 456                 return $this->getSqlFilePath( 'tables.sql' );
 457         }
 458
 459         /**
 460          * Return a path to the DBMS-specific update key file,
 461          * otherwise default to update-keys.sql
 462          *
 463          * @return string
 464          */
 465         public function getUpdateKeysPath() {
 466                 return $this->getSqlFilePath( 'update-keys.sql' );
 467         }
 468
 469         /**
 470          * Get information about an index into an object
 471          * @param string $table Table name
 472          * @param string $index Index name
 473          * @param string $fname Calling function name
 474          * @return mixed Database-specific index description class or false if the index does not exist
 475          */
 476         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 477
 478         /**
 479          * Wrapper for addslashes()
 480          *
 481          * @param string $s String to be slashed.
 482          * @return string Slashed string.
 483          */
 484         abstract function strencode( $s );
 485
 486         /**
 487          * Constructor.
 488          *
 489          * FIXME: It is possible to construct a Database object with no associated
 490          * connection object, by specifying no parameters to __construct(). This
 491          * feature is deprecated and should be removed.
 492          *
 493          * DatabaseBase subclasses should not be constructed directly in external
 494          * code. DatabaseBase::factory() should be used instead.
 495          *
 496          * @param array $params Parameters passed from DatabaseBase::factory()
 497          */
 498         function __construct( array $params ) {
 499                 global $wgDBprefix, $wgDBmwschema, $wgCommandLineMode;
 500
 501                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 502
 503                 $server = $params['host'];
 504                 $user = $params['user'];
 505                 $password = $params['password'];
 506                 $dbName = $params['dbname'];
 507                 $flags = $params['flags'];
 508                 $tablePrefix = $params['tablePrefix'];
 509                 $schema = $params['schema'];
 510                 $foreign = $params['foreign'];
 511
 512                 $this->mFlags = $flags;
 513                 if ( $this->mFlags & DBO_DEFAULT ) {
 514                         if ( $wgCommandLineMode ) {
 515                                 $this->mFlags &= ~DBO_TRX;
 516                         } else {
 517                                 $this->mFlags |= DBO_TRX;
 518                         }
 519                 }
 520
 521                 $this->mSessionVars = $params['variables'];
 522
 523                 /** Get the default table prefix*/
 524                 if ( $tablePrefix === 'get from global' ) {
 525                         $this->mTablePrefix = $wgDBprefix;
 526                 } else {
 527                         $this->mTablePrefix = $tablePrefix;
 528                 }
 529
 530                 /** Get the database schema*/
 531                 if ( $schema === 'get from global' ) {
 532                         $this->mSchema = $wgDBmwschema;
 533                 } else {
 534                         $this->mSchema = $schema;
 535                 }
 536
 537                 $this->mForeign = $foreign;
 538
 539                 if ( isset( $params['trxProfiler'] ) ) {
 540                         $this->trxProfiler = $params['trxProfiler']; // override
 541                 }
 542
 543                 if ( $user ) {
 544                         $this->open( $server, $user, $password, $dbName );
 545                 }
 546         }
 547
 548         /**
 549          * Called by serialize. Throw an exception when DB connection is serialized.
 550          * This causes problems on some database engines because the connection is
 551          * not restored on unserialize.
 552          */
 553         public function __sleep() {
 554                 throw new MWException( 'Database serialization may cause problems, since ' .
 555                         'the connection is not restored on wakeup.' );
 556         }
 557
 558         /**
 559          * Given a DB type, construct the name of the appropriate child class of
 560          * DatabaseBase. This is designed to replace all of the manual stuff like:
 561          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 562          * as well as validate against the canonical list of DB types we have
 563          *
 564          * This factory function is mostly useful for when you need to connect to a
 565          * database other than the MediaWiki default (such as for external auth,
 566          * an extension, et cetera). Do not use this to connect to the MediaWiki
 567          * database. Example uses in core:
 568          * @see LoadBalancer::reallyOpenConnection()
 569          * @see ForeignDBRepo::getMasterDB()
 570          * @see WebInstallerDBConnect::execute()
 571          *
 572          * @since 1.18
 573          *
 574          * @param string $dbType A possible DB type
 575          * @param array $p An array of options to pass to the constructor.
 576          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 577          * @throws MWException If the database driver or extension cannot be found
 578          * @return DatabaseBase|null DatabaseBase subclass or null
 579          */
 580         final public static function factory( $dbType, $p = array() ) {
 581                 $canonicalDBTypes = array(
 582                         'mysql' => array( 'mysqli', 'mysql' ),
 583                         'postgres' => array(),
 584                         'sqlite' => array(),
 585                         'oracle' => array(),
 586                         'mssql' => array(),
 587                 );
 588
 589                 $driver = false;
 590                 $dbType = strtolower( $dbType );
 591                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 592                         $possibleDrivers = $canonicalDBTypes[$dbType];
 593                         if ( !empty( $p['driver'] ) ) {
 594                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 595                                         $driver = $p['driver'];
 596                                 } else {
 597                                         throw new MWException( __METHOD__ .
 598                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 599                                 }
 600                         } else {
 601                                 foreach ( $possibleDrivers as $posDriver ) {
 602                                         if ( extension_loaded( $posDriver ) ) {
 603                                                 $driver = $posDriver;
 604                                                 break;
 605                                         }
 606                                 }
 607                         }
 608                 } else {
 609                         $driver = $dbType;
 610                 }
 611                 if ( $driver === false ) {
 612                         throw new MWException( __METHOD__ .
 613                                 " no viable database extension found for type '$dbType'" );
 614                 }
 615
 616                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 617                 // and everything else doesn't use a schema (e.g. null)
 618                 // Although postgres and oracle support schemas, we don't use them (yet)
 619                 // to maintain backwards compatibility
 620                 $defaultSchemas = array(
 621                         'mssql' => 'get from global',
 622                 );
 623
 624                 $class = 'Database' . ucfirst( $driver );
 625                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 626                         // Resolve some defaults for b/c
 627                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 628                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 629                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 630                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 631                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 632                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : array();
 633                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 634                         if ( !isset( $p['schema'] ) ) {
 635                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 636                         }
 637                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 638
 639                         return new $class( $p );
 640                 } else {
 641                         return null;
 642                 }
 643         }
 644
 645         protected function installErrorHandler() {
 646                 $this->mPHPError = false;
 647                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 648                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 649         }
 650
 651         /**
 652          * @return bool|string
 653          */
 654         protected function restoreErrorHandler() {
 655                 restore_error_handler();
 656                 if ( $this->htmlErrors !== false ) {
 657                         ini_set( 'html_errors', $this->htmlErrors );
 658                 }
 659                 if ( $this->mPHPError ) {
 660                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 661                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 662
 663                         return $error;
 664                 } else {
 665                         return false;
 666                 }
 667         }
 668
 669         /**
 670          * @param int $errno
 671          * @param string $errstr
 672          */
 673         public function connectionErrorHandler( $errno, $errstr ) {
 674                 $this->mPHPError = $errstr;
 675         }
 676
 677         /**
 678          * Create a log context to pass to wfLogDBError or other logging functions.
 679          *
 680          * @param array $extras Additional data to add to context
 681          * @return array
 682          */
 683         protected function getLogContext( array $extras = array() ) {
 684                 return array_merge(
 685                         array(
 686                                 'db_server' => $this->mServer,
 687                                 'db_name' => $this->mDBname,
 688                                 'db_user' => $this->mUser,
 689                         ),
 690                         $extras
 691                 );
 692         }
 693
 694         public function close() {
 695                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 696                         throw new MWException( "Transaction idle callbacks still pending." );
 697                 }
 698                 if ( $this->mConn ) {
 699                         if ( $this->trxLevel() ) {
 700                                 if ( !$this->mTrxAutomatic ) {
 701                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 702                                                 " performing implicit commit before closing connection!" );
 703                                 }
 704
 705                                 $this->commit( __METHOD__, 'flush' );
 706                         }
 707
 708                         $closed = $this->closeConnection();
 709                         $this->mConn = false;
 710                 } else {
 711                         $closed = true;
 712                 }
 713                 $this->mOpened = false;
 714
 715                 return $closed;
 716         }
 717
 718         /**
 719          * Make sure isOpen() returns true as a sanity check
 720          *
 721          * @throws DBUnexpectedError
 722          */
 723         protected function assertOpen() {
 724                 if ( !$this->isOpen() ) {
 725                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 726                 }
 727         }
 728
 729         /**
 730          * Closes underlying database connection
 731          * @since 1.20
 732          * @return bool Whether connection was closed successfully
 733          */
 734         abstract protected function closeConnection();
 735
 736         function reportConnectionError( $error = 'Unknown error' ) {
 737                 $myError = $this->lastError();
 738                 if ( $myError ) {
 739                         $error = $myError;
 740                 }
 741
 742                 # New method
 743                 throw new DBConnectionError( $this, $error );
 744         }
 745
 746         /**
 747          * The DBMS-dependent part of query()
 748          *
 749          * @param string $sql SQL query.
 750          * @return ResultWrapper|bool Result object to feed to fetchObject,
 751          *   fetchRow, ...; or false on failure
 752          */
 753         abstract protected function doQuery( $sql );
 754
 755         /**
 756          * Determine whether a query writes to the DB.
 757          * Should return true if unsure.
 758          *
 759          * @param string $sql
 760          * @return bool
 761          */
 762         protected function isWriteQuery( $sql ) {
 763                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 764         }
 765
 766         /**
 767          * Determine whether a SQL statement is sensitive to isolation level.
 768          * A SQL statement is considered transactable if its result could vary
 769          * depending on the transaction isolation level. Operational commands
 770          * such as 'SET' and 'SHOW' are not considered to be transactable.
 771          *
 772          * @param string $sql
 773          * @return bool
 774          */
 775         protected function isTransactableQuery( $sql ) {
 776                 $verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
 777                 return !in_array( $verb, array( 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ) );
 778         }
 779
 780         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 781                 global $wgUser;
 782
 783                 $this->mLastQuery = $sql;
 784
 785                 $isWriteQuery = $this->isWriteQuery( $sql );
 786                 if ( $isWriteQuery ) {
 787                         $reason = $this->getReadOnlyReason();
 788                         if ( $reason !== false ) {
 789                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 790                         }
 791                         # Set a flag indicating that writes have been done
 792                         $this->mDoneWrites = microtime( true );
 793                 }
 794
 795                 # Add a comment for easy SHOW PROCESSLIST interpretation
 796                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 797                         $userName = $wgUser->getName();
 798                         if ( mb_strlen( $userName ) > 15 ) {
 799                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 800                         }
 801                         $userName = str_replace( '/', '', $userName );
 802                 } else {
 803                         $userName = '';
 804                 }
 805
 806                 // Add trace comment to the begin of the sql string, right after the operator.
 807                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 808                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 809
 810                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX ) && $this->isTransactableQuery( $sql ) ) {
 811                         $this->begin( __METHOD__ . " ($fname)" );
 812                         $this->mTrxAutomatic = true;
 813                 }
 814
 815                 # Keep track of whether the transaction has write queries pending
 816                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWriteQuery ) {
 817                         $this->mTrxDoneWrites = true;
 818                         $this->getTransactionProfiler()->transactionWritingIn(
 819                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 820                 }
 821
 822                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 823                 # generalizeSQL will probably cut down the query to reasonable
 824                 # logging size most of the time. The substr is really just a sanity check.
 825                 if ( $isMaster ) {
 826                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 827                         $totalProf = 'DatabaseBase::query-master';
 828                 } else {
 829                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 830                         $totalProf = 'DatabaseBase::query';
 831                 }
 832                 # Include query transaction state
 833                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 834
 835                 $profiler = Profiler::instance();
 836                 if ( !$profiler instanceof ProfilerStub ) {
 837                         $totalProfSection = $profiler->scopedProfileIn( $totalProf );
 838                         $queryProfSection = $profiler->scopedProfileIn( $queryProf );
 839                 }
 840
 841                 if ( $this->debug() ) {
 842                         wfDebugLog( 'queries', sprintf( "%s: %s", $this->mDBname, $commentedSql ) );
 843                 }
 844
 845                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 846
 847                 # Avoid fatals if close() was called
 848                 $this->assertOpen();
 849
 850                 # Do the query and handle errors
 851                 $startTime = microtime( true );
 852                 $ret = $this->doQuery( $commentedSql );
 853                 $queryRuntime = microtime( true ) - $startTime;
 854                 # Log the query time and feed it into the DB trx profiler
 855                 $this->getTransactionProfiler()->recordQueryCompletion(
 856                         $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
 857
 858                 MWDebug::queryTime( $queryId );
 859
 860                 # Try reconnecting if the connection was lost
 861                 if ( false === $ret && $this->wasErrorReissuable() ) {
 862                         # Transaction is gone, like it or not
 863                         $hadTrx = $this->mTrxLevel; // possible lost transaction
 864                         $this->mTrxLevel = 0;
 865                         $this->mTrxIdleCallbacks = array(); // bug 65263
 866                         $this->mTrxPreCommitCallbacks = array(); // bug 65263
 867                         wfDebug( "Connection lost, reconnecting...\n" );
 868                         # Stash the last error values since ping() might clear them
 869                         $lastError = $this->lastError();
 870                         $lastErrno = $this->lastErrno();
 871                         if ( $this->ping() ) {
 872                                 wfDebug( "Reconnected\n" );
 873                                 $server = $this->getServer();
 874                                 $msg = __METHOD__ . ": lost connection to $server; reconnected";
 875                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
 876
 877                                 if ( $hadTrx || $this->mNamedLocksHeld ) {
 878                                         # Leave $ret as false and let an error be reported.
 879                                         # Callers may catch the exception and continue to use the DB.
 880                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
 881                                 } else {
 882                                         # Should be safe to silently retry (no trx and thus no callbacks)
 883                                         $startTime = microtime( true );
 884                                         $ret = $this->doQuery( $commentedSql );
 885                                         $queryRuntime = microtime( true ) - $startTime;
 886                                         # Log the query time and feed it into the DB trx profiler
 887                                         $this->getTransactionProfiler()->recordQueryCompletion(
 888                                                 $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
 889                                 }
 890                         } else {
 891                                 wfDebug( "Failed\n" );
 892                         }
 893                 }
 894
 895                 if ( false === $ret ) {
 896                         $this->reportQueryError(
 897                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 898                 }
 899
 900                 $res = $this->resultObject( $ret );
 901
 902                 // Destroy profile sections in the opposite order to their creation
 903                 ScopedCallback::consume( $queryProfSection );
 904                 ScopedCallback::consume( $totalProfSection );
 905
 906                 if ( $isWriteQuery && $this->mTrxLevel ) {
 907                         $this->mTrxWriteDuration += $queryRuntime;
 908                         $this->mTrxWriteCallers[] = $fname;
 909                 }
 910
 911                 return $res;
 912         }
 913
 914         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 915                 if ( $this->ignoreErrors() || $tempIgnore ) {
 916                         wfDebug( "SQL ERROR (ignored): $error\n" );
 917                 } else {
 918                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
 919                         wfLogDBError(
 920                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
 921                                 $this->getLogContext( array(
 922                                         'method' => __METHOD__,
 923                                         'errno' => $errno,
 924                                         'error' => $error,
 925                                         'sql1line' => $sql1line,
 926                                         'fname' => $fname,
 927                                 ) )
 928                         );
 929                         wfDebug( "SQL ERROR: " . $error . "\n" );
 930                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 931                 }
 932         }
 933
 934         /**
 935          * Intended to be compatible with the PEAR::DB wrapper functions.
 936          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 937          *
 938          * ? = scalar value, quoted as necessary
 939          * ! = raw SQL bit (a function for instance)
 940          * & = filename; reads the file and inserts as a blob
 941          *     (we don't use this though...)
 942          *
 943          * @param string $sql
 944          * @param string $func
 945          *
 946          * @return array
 947          */
 948         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 949                 /* MySQL doesn't support prepared statements (yet), so just
 950                  * pack up the query for reference. We'll manually replace
 951                  * the bits later.
 952                  */
 953                 return array( 'query' => $sql, 'func' => $func );
 954         }
 955
 956         /**
 957          * Free a prepared query, generated by prepare().
 958          * @param string $prepared
 959          */
 960         protected function freePrepared( $prepared ) {
 961                 /* No-op by default */
 962         }
 963
 964         /**
 965          * Execute a prepared query with the various arguments
 966          * @param string $prepared The prepared sql
 967          * @param mixed $args Either an array here, or put scalars as varargs
 968          *
 969          * @return ResultWrapper
 970          */
 971         public function execute( $prepared, $args = null ) {
 972                 if ( !is_array( $args ) ) {
 973                         # Pull the var args
 974                         $args = func_get_args();
 975                         array_shift( $args );
 976                 }
 977
 978                 $sql = $this->fillPrepared( $prepared['query'], $args );
 979
 980                 return $this->query( $sql, $prepared['func'] );
 981         }
 982
 983         /**
 984          * For faking prepared SQL statements on DBs that don't support it directly.
 985          *
 986          * @param string $preparedQuery A 'preparable' SQL statement
 987          * @param array $args Array of Arguments to fill it with
 988          * @return string Executable SQL
 989          */
 990         public function fillPrepared( $preparedQuery, $args ) {
 991                 reset( $args );
 992                 $this->preparedArgs =& $args;
 993
 994                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 995                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 996         }
 997
 998         /**
 999          * preg_callback func for fillPrepared()
1000          * The arguments should be in $this->preparedArgs and must not be touched
1001          * while we're doing this.
1002          *
1003          * @param array $matches
1004          * @throws DBUnexpectedError
1005          * @return string
1006          */
1007         protected function fillPreparedArg( $matches ) {
1008                 switch ( $matches[1] ) {
1009                         case '\\?':
1010                                 return '?';
1011                         case '\\!':
1012                                 return '!';
1013                         case '\\&':
1014                                 return '&';
1015                 }
1016
1017                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1018
1019                 switch ( $matches[1] ) {
1020                         case '?':
1021                                 return $this->addQuotes( $arg );
1022                         case '!':
1023                                 return $arg;
1024                         case '&':
1025                                 # return $this->addQuotes( file_get_contents( $arg ) );
1026                                 throw new DBUnexpectedError(
1027                                         $this,
1028                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1029                                 );
1030                         default:
1031                                 throw new DBUnexpectedError(
1032                                         $this,
1033                                         'Received invalid match. This should never happen!'
1034                                 );
1035                 }
1036         }
1037
1038         public function freeResult( $res ) {
1039         }
1040
1041         public function selectField(
1042                 $table, $var, $cond = '', $fname = __METHOD__, $options = array()
1043         ) {
1044                 if ( $var === '*' ) { // sanity
1045                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1046                 }
1047
1048                 if ( !is_array( $options ) ) {
1049                         $options = array( $options );
1050                 }
1051
1052                 $options['LIMIT'] = 1;
1053
1054                 $res = $this->select( $table, $var, $cond, $fname, $options );
1055                 if ( $res === false || !$this->numRows( $res ) ) {
1056                         return false;
1057                 }
1058
1059                 $row = $this->fetchRow( $res );
1060
1061                 if ( $row !== false ) {
1062                         return reset( $row );
1063                 } else {
1064                         return false;
1065                 }
1066         }
1067
1068         public function selectFieldValues(
1069                 $table, $var, $cond = '', $fname = __METHOD__, $options = array(), $join_conds = array()
1070         ) {
1071                 if ( $var === '*' ) { // sanity
1072                         throw new DBUnexpectedError( $this, "Cannot use a * field" );
1073                 } elseif ( !is_string( $var ) ) { // sanity
1074                         throw new DBUnexpectedError( $this, "Cannot use an array of fields" );
1075                 }
1076
1077                 if ( !is_array( $options ) ) {
1078                         $options = array( $options );
1079                 }
1080
1081                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1082                 if ( $res === false ) {
1083                         return false;
1084                 }
1085
1086                 $values = array();
1087                 foreach ( $res as $row ) {
1088                         $values[] = $row->$var;
1089                 }
1090
1091                 return $values;
1092         }
1093
1094         /**
1095          * Returns an optional USE INDEX clause to go after the table, and a
1096          * string to go at the end of the query.
1097          *
1098          * @param array $options Associative array of options to be turned into
1099          *   an SQL query, valid keys are listed in the function.
1100          * @return array
1101          * @see DatabaseBase::select()
1102          */
1103         public function makeSelectOptions( $options ) {
1104                 $preLimitTail = $postLimitTail = '';
1105                 $startOpts = '';
1106
1107                 $noKeyOptions = array();
1108
1109                 foreach ( $options as $key => $option ) {
1110                         if ( is_numeric( $key ) ) {
1111                                 $noKeyOptions[$option] = true;
1112                         }
1113                 }
1114
1115                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1116
1117                 $preLimitTail .= $this->makeOrderBy( $options );
1118
1119                 // if (isset($options['LIMIT'])) {
1120                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1121                 //              isset($options['OFFSET']) ? $options['OFFSET']
1122                 //              : false);
1123                 // }
1124
1125                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1126                         $postLimitTail .= ' FOR UPDATE';
1127                 }
1128
1129                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1130                         $postLimitTail .= ' LOCK IN SHARE MODE';
1131                 }
1132
1133                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1134                         $startOpts .= 'DISTINCT';
1135                 }
1136
1137                 # Various MySQL extensions
1138                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1139                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1140                 }
1141
1142                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1143                         $startOpts .= ' HIGH_PRIORITY';
1144                 }
1145
1146                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1147                         $startOpts .= ' SQL_BIG_RESULT';
1148                 }
1149
1150                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1151                         $startOpts .= ' SQL_BUFFER_RESULT';
1152                 }
1153
1154                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1155                         $startOpts .= ' SQL_SMALL_RESULT';
1156                 }
1157
1158                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1159                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1160                 }
1161
1162                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1163                         $startOpts .= ' SQL_CACHE';
1164                 }
1165
1166                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1167                         $startOpts .= ' SQL_NO_CACHE';
1168                 }
1169
1170                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1171                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1172                 } else {
1173                         $useIndex = '';
1174                 }
1175
1176                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1177         }
1178
1179         /**
1180          * Returns an optional GROUP BY with an optional HAVING
1181          *
1182          * @param array $options Associative array of options
1183          * @return string
1184          * @see DatabaseBase::select()
1185          * @since 1.21
1186          */
1187         public function makeGroupByWithHaving( $options ) {
1188                 $sql = '';
1189                 if ( isset( $options['GROUP BY'] ) ) {
1190                         $gb = is_array( $options['GROUP BY'] )
1191                                 ? implode( ',', $options['GROUP BY'] )
1192                                 : $options['GROUP BY'];
1193                         $sql .= ' GROUP BY ' . $gb;
1194                 }
1195                 if ( isset( $options['HAVING'] ) ) {
1196                         $having = is_array( $options['HAVING'] )
1197                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1198                                 : $options['HAVING'];
1199                         $sql .= ' HAVING ' . $having;
1200                 }
1201
1202                 return $sql;
1203         }
1204
1205         /**
1206          * Returns an optional ORDER BY
1207          *
1208          * @param array $options Associative array of options
1209          * @return string
1210          * @see DatabaseBase::select()
1211          * @since 1.21
1212          */
1213         public function makeOrderBy( $options ) {
1214                 if ( isset( $options['ORDER BY'] ) ) {
1215                         $ob = is_array( $options['ORDER BY'] )
1216                                 ? implode( ',', $options['ORDER BY'] )
1217                                 : $options['ORDER BY'];
1218
1219                         return ' ORDER BY ' . $ob;
1220                 }
1221
1222                 return '';
1223         }
1224
1225         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1226                 $options = array(), $join_conds = array() ) {
1227                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1228
1229                 return $this->query( $sql, $fname );
1230         }
1231
1232         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1233                 $options = array(), $join_conds = array()
1234         ) {
1235                 if ( is_array( $vars ) ) {
1236                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1237                 }
1238
1239                 $options = (array)$options;
1240                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1241                         ? $options['USE INDEX']
1242                         : array();
1243
1244                 if ( is_array( $table ) ) {
1245                         $from = ' FROM ' .
1246                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1247                 } elseif ( $table != '' ) {
1248                         if ( $table[0] == ' ' ) {
1249                                 $from = ' FROM ' . $table;
1250                         } else {
1251                                 $from = ' FROM ' .
1252                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1253                         }
1254                 } else {
1255                         $from = '';
1256                 }
1257
1258                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1259                         $this->makeSelectOptions( $options );
1260
1261                 if ( !empty( $conds ) ) {
1262                         if ( is_array( $conds ) ) {
1263                                 $conds = $this->makeList( $conds, LIST_AND );
1264                         }
1265                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1266                 } else {
1267                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1268                 }
1269
1270                 if ( isset( $options['LIMIT'] ) ) {
1271                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1272                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1273                 }
1274                 $sql = "$sql $postLimitTail";
1275
1276                 if ( isset( $options['EXPLAIN'] ) ) {
1277                         $sql = 'EXPLAIN ' . $sql;
1278                 }
1279
1280                 return $sql;
1281         }
1282
1283         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1284                 $options = array(), $join_conds = array()
1285         ) {
1286                 $options = (array)$options;
1287                 $options['LIMIT'] = 1;
1288                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1289
1290                 if ( $res === false ) {
1291                         return false;
1292                 }
1293
1294                 if ( !$this->numRows( $res ) ) {
1295                         return false;
1296                 }
1297
1298                 $obj = $this->fetchObject( $res );
1299
1300                 return $obj;
1301         }
1302
1303         public function estimateRowCount(
1304                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
1305         ) {
1306                 $rows = 0;
1307                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1308
1309                 if ( $res ) {
1310                         $row = $this->fetchRow( $res );
1311                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1312                 }
1313
1314                 return $rows;
1315         }
1316
1317         public function selectRowCount(
1318                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = array(), $join_conds = array()
1319         ) {
1320                 $rows = 0;
1321                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1322                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1323
1324                 if ( $res ) {
1325                         $row = $this->fetchRow( $res );
1326                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1327                 }
1328
1329                 return $rows;
1330         }
1331
1332         /**
1333          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1334          * It's only slightly flawed. Don't use for anything important.
1335          *
1336          * @param string $sql A SQL Query
1337          *
1338          * @return string
1339          */
1340         protected static function generalizeSQL( $sql ) {
1341                 # This does the same as the regexp below would do, but in such a way
1342                 # as to avoid crashing php on some large strings.
1343                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1344
1345                 $sql = str_replace( "\\\\", '', $sql );
1346                 $sql = str_replace( "\\'", '', $sql );
1347                 $sql = str_replace( "\\\"", '', $sql );
1348                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1349                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1350
1351                 # All newlines, tabs, etc replaced by single space
1352                 $sql = preg_replace( '/\s+/', ' ', $sql );
1353
1354                 # All numbers => N,
1355                 # except the ones surrounded by characters, e.g. l10n
1356                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1357                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1358
1359                 return $sql;
1360         }
1361
1362         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1363                 $info = $this->fieldInfo( $table, $field );
1364
1365                 return (bool)$info;
1366         }
1367
1368         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1369                 if ( !$this->tableExists( $table ) ) {
1370                         return null;
1371                 }
1372
1373                 $info = $this->indexInfo( $table, $index, $fname );
1374                 if ( is_null( $info ) ) {
1375                         return null;
1376                 } else {
1377                         return $info !== false;
1378                 }
1379         }
1380
1381         public function tableExists( $table, $fname = __METHOD__ ) {
1382                 $table = $this->tableName( $table );
1383                 $old = $this->ignoreErrors( true );
1384                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1385                 $this->ignoreErrors( $old );
1386
1387                 return (bool)$res;
1388         }
1389
1390         public function indexUnique( $table, $index ) {
1391                 $indexInfo = $this->indexInfo( $table, $index );
1392
1393                 if ( !$indexInfo ) {
1394                         return null;
1395                 }
1396
1397                 return !$indexInfo[0]->Non_unique;
1398         }
1399
1400         /**
1401          * Helper for DatabaseBase::insert().
1402          *
1403          * @param array $options
1404          * @return string
1405          */
1406         protected function makeInsertOptions( $options ) {
1407                 return implode( ' ', $options );
1408         }
1409
1410         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
1411                 # No rows to insert, easy just return now
1412                 if ( !count( $a ) ) {
1413                         return true;
1414                 }
1415
1416                 $table = $this->tableName( $table );
1417
1418                 if ( !is_array( $options ) ) {
1419                         $options = array( $options );
1420                 }
1421
1422                 $fh = null;
1423                 if ( isset( $options['fileHandle'] ) ) {
1424                         $fh = $options['fileHandle'];
1425                 }
1426                 $options = $this->makeInsertOptions( $options );
1427
1428                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1429                         $multi = true;
1430                         $keys = array_keys( $a[0] );
1431                 } else {
1432                         $multi = false;
1433                         $keys = array_keys( $a );
1434                 }
1435
1436                 $sql = 'INSERT ' . $options .
1437                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1438
1439                 if ( $multi ) {
1440                         $first = true;
1441                         foreach ( $a as $row ) {
1442                                 if ( $first ) {
1443                                         $first = false;
1444                                 } else {
1445                                         $sql .= ',';
1446                                 }
1447                                 $sql .= '(' . $this->makeList( $row ) . ')';
1448                         }
1449                 } else {
1450                         $sql .= '(' . $this->makeList( $a ) . ')';
1451                 }
1452
1453                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1454                         return false;
1455                 } elseif ( $fh !== null ) {
1456                         return true;
1457                 }
1458
1459                 return (bool)$this->query( $sql, $fname );
1460         }
1461
1462         /**
1463          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1464          *
1465          * @param array $options
1466          * @return array
1467          */
1468         protected function makeUpdateOptionsArray( $options ) {
1469                 if ( !is_array( $options ) ) {
1470                         $options = array( $options );
1471                 }
1472
1473                 $opts = array();
1474
1475                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1476                         $opts[] = $this->lowPriorityOption();
1477                 }
1478
1479                 if ( in_array( 'IGNORE', $options ) ) {
1480                         $opts[] = 'IGNORE';
1481                 }
1482
1483                 return $opts;
1484         }
1485
1486         /**
1487          * Make UPDATE options for the DatabaseBase::update function
1488          *
1489          * @param array $options The options passed to DatabaseBase::update
1490          * @return string
1491          */
1492         protected function makeUpdateOptions( $options ) {
1493                 $opts = $this->makeUpdateOptionsArray( $options );
1494
1495                 return implode( ' ', $opts );
1496         }
1497
1498         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
1499                 $table = $this->tableName( $table );
1500                 $opts = $this->makeUpdateOptions( $options );
1501                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1502
1503                 if ( $conds !== array() && $conds !== '*' ) {
1504                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1505                 }
1506
1507                 return $this->query( $sql, $fname );
1508         }
1509
1510         public function makeList( $a, $mode = LIST_COMMA ) {
1511                 if ( !is_array( $a ) ) {
1512                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1513                 }
1514
1515                 $first = true;
1516                 $list = '';
1517
1518                 foreach ( $a as $field => $value ) {
1519                         if ( !$first ) {
1520                                 if ( $mode == LIST_AND ) {
1521                                         $list .= ' AND ';
1522                                 } elseif ( $mode == LIST_OR ) {
1523                                         $list .= ' OR ';
1524                                 } else {
1525                                         $list .= ',';
1526                                 }
1527                         } else {
1528                                 $first = false;
1529                         }
1530
1531                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1532                                 $list .= "($value)";
1533                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1534                                 $list .= "$value";
1535                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1536                                 // Remove null from array to be handled separately if found
1537                                 $includeNull = false;
1538                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1539                                         $includeNull = true;
1540                                         unset( $value[$nullKey] );
1541                                 }
1542                                 if ( count( $value ) == 0 && !$includeNull ) {
1543                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1544                                 } elseif ( count( $value ) == 0 ) {
1545                                         // only check if $field is null
1546                                         $list .= "$field IS NULL";
1547                                 } else {
1548                                         // IN clause contains at least one valid element
1549                                         if ( $includeNull ) {
1550                                                 // Group subconditions to ensure correct precedence
1551                                                 $list .= '(';
1552                                         }
1553                                         if ( count( $value ) == 1 ) {
1554                                                 // Special-case single values, as IN isn't terribly efficient
1555                                                 // Don't necessarily assume the single key is 0; we don't
1556                                                 // enforce linear numeric ordering on other arrays here.
1557                                                 $value = array_values( $value );
1558                                                 $list .= $field . " = " . $this->addQuotes( $value[0] );
1559                                         } else {
1560                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1561                                         }
1562                                         // if null present in array, append IS NULL
1563                                         if ( $includeNull ) {
1564                                                 $list .= " OR $field IS NULL)";
1565                                         }
1566                                 }
1567                         } elseif ( $value === null ) {
1568                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1569                                         $list .= "$field IS ";
1570                                 } elseif ( $mode == LIST_SET ) {
1571                                         $list .= "$field = ";
1572                                 }
1573                                 $list .= 'NULL';
1574                         } else {
1575                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1576                                         $list .= "$field = ";
1577                                 }
1578                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1579                         }
1580                 }
1581
1582                 return $list;
1583         }
1584
1585         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1586                 $conds = array();
1587
1588                 foreach ( $data as $base => $sub ) {
1589                         if ( count( $sub ) ) {
1590                                 $conds[] = $this->makeList(
1591                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1592                                         LIST_AND );
1593                         }
1594                 }
1595
1596                 if ( $conds ) {
1597                         return $this->makeList( $conds, LIST_OR );
1598                 } else {
1599                         // Nothing to search for...
1600                         return false;
1601                 }
1602         }
1603
1604         /**
1605          * Return aggregated value alias
1606          *
1607          * @param array $valuedata
1608          * @param string $valuename
1609          *
1610          * @return string
1611          */
1612         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1613                 return $valuename;
1614         }
1615
1616         public function bitNot( $field ) {
1617                 return "(~$field)";
1618         }
1619
1620         public function bitAnd( $fieldLeft, $fieldRight ) {
1621                 return "($fieldLeft & $fieldRight)";
1622         }
1623
1624         public function bitOr( $fieldLeft, $fieldRight ) {
1625                 return "($fieldLeft | $fieldRight)";
1626         }
1627
1628         public function buildConcat( $stringList ) {
1629                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1630         }
1631
1632         public function buildGroupConcatField(
1633                 $delim, $table, $field, $conds = '', $join_conds = array()
1634         ) {
1635                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1636
1637                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, array(), $join_conds ) . ')';
1638         }
1639
1640         public function selectDB( $db ) {
1641                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1642                 # if your database engine supports a concept similar to MySQL's
1643                 # databases you may as well.
1644                 $this->mDBname = $db;
1645
1646                 return true;
1647         }
1648
1649         public function getDBname() {
1650                 return $this->mDBname;
1651         }
1652
1653         public function getServer() {
1654                 return $this->mServer;
1655         }
1656
1657         /**
1658          * Format a table name ready for use in constructing an SQL query
1659          *
1660          * This does two important things: it quotes the table names to clean them up,
1661          * and it adds a table prefix if only given a table name with no quotes.
1662          *
1663          * All functions of this object which require a table name call this function
1664          * themselves. Pass the canonical name to such functions. This is only needed
1665          * when calling query() directly.
1666          *
1667          * @param string $name Database table name
1668          * @param string $format One of:
1669          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1670          *            so that it can be used in a query.
1671          *   raw - Do not add identifier quotes to the table name
1672          * @return string Full database name
1673          */
1674         public function tableName( $name, $format = 'quoted' ) {
1675                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1676                 # Skip the entire process when we have a string quoted on both ends.
1677                 # Note that we check the end so that we will still quote any use of
1678                 # use of `database`.table. But won't break things if someone wants
1679                 # to query a database table with a dot in the name.
1680                 if ( $this->isQuotedIdentifier( $name ) ) {
1681                         return $name;
1682                 }
1683
1684                 # Lets test for any bits of text that should never show up in a table
1685                 # name. Basically anything like JOIN or ON which are actually part of
1686                 # SQL queries, but may end up inside of the table value to combine
1687                 # sql. Such as how the API is doing.
1688                 # Note that we use a whitespace test rather than a \b test to avoid
1689                 # any remote case where a word like on may be inside of a table name
1690                 # surrounded by symbols which may be considered word breaks.
1691                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1692                         return $name;
1693                 }
1694
1695                 # Split database and table into proper variables.
1696                 # We reverse the explode so that database.table and table both output
1697                 # the correct table.
1698                 $dbDetails = explode( '.', $name, 3 );
1699                 if ( count( $dbDetails ) == 3 ) {
1700                         list( $database, $schema, $table ) = $dbDetails;
1701                         # We don't want any prefix added in this case
1702                         $prefix = '';
1703                 } elseif ( count( $dbDetails ) == 2 ) {
1704                         list( $database, $table ) = $dbDetails;
1705                         # We don't want any prefix added in this case
1706                         # In dbs that support it, $database may actually be the schema
1707                         # but that doesn't affect any of the functionality here
1708                         $prefix = '';
1709                         $schema = null;
1710                 } else {
1711                         list( $table ) = $dbDetails;
1712                         if ( $wgSharedDB !== null # We have a shared database
1713                                 && $this->mForeign == false # We're not working on a foreign database
1714                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1715                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1716                         ) {
1717                                 $database = $wgSharedDB;
1718                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1719                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1720                         } else {
1721                                 $database = null;
1722                                 $schema = $this->mSchema; # Default schema
1723                                 $prefix = $this->mTablePrefix; # Default prefix
1724                         }
1725                 }
1726
1727                 # Quote $table and apply the prefix if not quoted.
1728                 # $tableName might be empty if this is called from Database::replaceVars()
1729                 $tableName = "{$prefix}{$table}";
1730                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1731                         $tableName = $this->addIdentifierQuotes( $tableName );
1732                 }
1733
1734                 # Quote $schema and merge it with the table name if needed
1735                 if ( strlen( $schema ) ) {
1736                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1737                                 $schema = $this->addIdentifierQuotes( $schema );
1738                         }
1739                         $tableName = $schema . '.' . $tableName;
1740                 }
1741
1742                 # Quote $database and merge it with the table name if needed
1743                 if ( $database !== null ) {
1744                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1745                                 $database = $this->addIdentifierQuotes( $database );
1746                         }
1747                         $tableName = $database . '.' . $tableName;
1748                 }
1749
1750                 return $tableName;
1751         }
1752
1753         /**
1754          * Fetch a number of table names into an array
1755          * This is handy when you need to construct SQL for joins
1756          *
1757          * Example:
1758          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1759          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1760          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1761          *
1762          * @return array
1763          */
1764         public function tableNames() {
1765                 $inArray = func_get_args();
1766                 $retVal = array();
1767
1768                 foreach ( $inArray as $name ) {
1769                         $retVal[$name] = $this->tableName( $name );
1770                 }
1771
1772                 return $retVal;
1773         }
1774
1775         /**
1776          * Fetch a number of table names into an zero-indexed numerical array
1777          * This is handy when you need to construct SQL for joins
1778          *
1779          * Example:
1780          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1781          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1782          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1783          *
1784          * @return array
1785          */
1786         public function tableNamesN() {
1787                 $inArray = func_get_args();
1788                 $retVal = array();
1789
1790                 foreach ( $inArray as $name ) {
1791                         $retVal[] = $this->tableName( $name );
1792                 }
1793
1794                 return $retVal;
1795         }
1796
1797         /**
1798          * Get an aliased table name
1799          * e.g. tableName AS newTableName
1800          *
1801          * @param string $name Table name, see tableName()
1802          * @param string|bool $alias Alias (optional)
1803          * @return string SQL name for aliased table. Will not alias a table to its own name
1804          */
1805         public function tableNameWithAlias( $name, $alias = false ) {
1806                 if ( !$alias || $alias == $name ) {
1807                         return $this->tableName( $name );
1808                 } else {
1809                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1810                 }
1811         }
1812
1813         /**
1814          * Gets an array of aliased table names
1815          *
1816          * @param array $tables Array( [alias] => table )
1817          * @return string[] See tableNameWithAlias()
1818          */
1819         public function tableNamesWithAlias( $tables ) {
1820                 $retval = array();
1821                 foreach ( $tables as $alias => $table ) {
1822                         if ( is_numeric( $alias ) ) {
1823                                 $alias = $table;
1824                         }
1825                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1826                 }
1827
1828                 return $retval;
1829         }
1830
1831         /**
1832          * Get an aliased field name
1833          * e.g. fieldName AS newFieldName
1834          *
1835          * @param string $name Field name
1836          * @param string|bool $alias Alias (optional)
1837          * @return string SQL name for aliased field. Will not alias a field to its own name
1838          */
1839         public function fieldNameWithAlias( $name, $alias = false ) {
1840                 if ( !$alias || (string)$alias === (string)$name ) {
1841                         return $name;
1842                 } else {
1843                         return $name . ' AS ' . $alias; // PostgreSQL needs AS
1844                 }
1845         }
1846
1847         /**
1848          * Gets an array of aliased field names
1849          *
1850          * @param array $fields Array( [alias] => field )
1851          * @return string[] See fieldNameWithAlias()
1852          */
1853         public function fieldNamesWithAlias( $fields ) {
1854                 $retval = array();
1855                 foreach ( $fields as $alias => $field ) {
1856                         if ( is_numeric( $alias ) ) {
1857                                 $alias = $field;
1858                         }
1859                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1860                 }
1861
1862                 return $retval;
1863         }
1864
1865         /**
1866          * Get the aliased table name clause for a FROM clause
1867          * which might have a JOIN and/or USE INDEX clause
1868          *
1869          * @param array $tables ( [alias] => table )
1870          * @param array $use_index Same as for select()
1871          * @param array $join_conds Same as for select()
1872          * @return string
1873          */
1874         protected function tableNamesWithUseIndexOrJOIN(
1875                 $tables, $use_index = array(), $join_conds = array()
1876         ) {
1877                 $ret = array();
1878                 $retJOIN = array();
1879                 $use_index = (array)$use_index;
1880                 $join_conds = (array)$join_conds;
1881
1882                 foreach ( $tables as $alias => $table ) {
1883                         if ( !is_string( $alias ) ) {
1884                                 // No alias? Set it equal to the table name
1885                                 $alias = $table;
1886                         }
1887                         // Is there a JOIN clause for this table?
1888                         if ( isset( $join_conds[$alias] ) ) {
1889                                 list( $joinType, $conds ) = $join_conds[$alias];
1890                                 $tableClause = $joinType;
1891                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1892                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1893                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1894                                         if ( $use != '' ) {
1895                                                 $tableClause .= ' ' . $use;
1896                                         }
1897                                 }
1898                                 $on = $this->makeList( (array)$conds, LIST_AND );
1899                                 if ( $on != '' ) {
1900                                         $tableClause .= ' ON (' . $on . ')';
1901                                 }
1902
1903                                 $retJOIN[] = $tableClause;
1904                         } elseif ( isset( $use_index[$alias] ) ) {
1905                                 // Is there an INDEX clause for this table?
1906                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1907                                 $tableClause .= ' ' . $this->useIndexClause(
1908                                         implode( ',', (array)$use_index[$alias] )
1909                                 );
1910
1911                                 $ret[] = $tableClause;
1912                         } else {
1913                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1914
1915                                 $ret[] = $tableClause;
1916                         }
1917                 }
1918
1919                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1920                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1921                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1922
1923                 // Compile our final table clause
1924                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
1925         }
1926
1927         /**
1928          * Get the name of an index in a given table.
1929          *
1930          * @param string $index
1931          * @return string
1932          */
1933         protected function indexName( $index ) {
1934                 // Backwards-compatibility hack
1935                 $renamed = array(
1936                         'ar_usertext_timestamp' => 'usertext_timestamp',
1937                         'un_user_id' => 'user_id',
1938                         'un_user_ip' => 'user_ip',
1939                 );
1940
1941                 if ( isset( $renamed[$index] ) ) {
1942                         return $renamed[$index];
1943                 } else {
1944                         return $index;
1945                 }
1946         }
1947
1948         public function addQuotes( $s ) {
1949                 if ( $s instanceof Blob ) {
1950                         $s = $s->fetch();
1951                 }
1952                 if ( $s === null ) {
1953                         return 'NULL';
1954                 } else {
1955                         # This will also quote numeric values. This should be harmless,
1956                         # and protects against weird problems that occur when they really
1957                         # _are_ strings such as article titles and string->number->string
1958                         # conversion is not 1:1.
1959                         return "'" . $this->strencode( $s ) . "'";
1960                 }
1961         }
1962
1963         /**
1964          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1965          * MySQL uses `backticks` while basically everything else uses double quotes.
1966          * Since MySQL is the odd one out here the double quotes are our generic
1967          * and we implement backticks in DatabaseMysql.
1968          *
1969          * @param string $s
1970          * @return string
1971          */
1972         public function addIdentifierQuotes( $s ) {
1973                 return '"' . str_replace( '"', '""', $s ) . '"';
1974         }
1975
1976         /**
1977          * Returns if the given identifier looks quoted or not according to
1978          * the database convention for quoting identifiers .
1979          *
1980          * @param string $name
1981          * @return bool
1982          */
1983         public function isQuotedIdentifier( $name ) {
1984                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1985         }
1986
1987         /**
1988          * @param string $s
1989          * @return string
1990          */
1991         protected function escapeLikeInternal( $s ) {
1992                 return addcslashes( $s, '\%_' );
1993         }
1994
1995         public function buildLike() {
1996                 $params = func_get_args();
1997
1998                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1999                         $params = $params[0];
2000                 }
2001
2002                 $s = '';
2003
2004                 foreach ( $params as $value ) {
2005                         if ( $value instanceof LikeMatch ) {
2006                                 $s .= $value->toString();
2007                         } else {
2008                                 $s .= $this->escapeLikeInternal( $value );
2009                         }
2010                 }
2011
2012                 return " LIKE {$this->addQuotes( $s )} ";
2013         }
2014
2015         public function anyChar() {
2016                 return new LikeMatch( '_' );
2017         }
2018
2019         public function anyString() {
2020                 return new LikeMatch( '%' );
2021         }
2022
2023         public function nextSequenceValue( $seqName ) {
2024                 return null;
2025         }
2026
2027         /**
2028          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2029          * is only needed because a) MySQL must be as efficient as possible due to
2030          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2031          * which index to pick. Anyway, other databases might have different
2032          * indexes on a given table. So don't bother overriding this unless you're
2033          * MySQL.
2034          * @param string $index
2035          * @return string
2036          */
2037         public function useIndexClause( $index ) {
2038                 return '';
2039         }
2040
2041         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2042                 $quotedTable = $this->tableName( $table );
2043
2044                 if ( count( $rows ) == 0 ) {
2045                         return;
2046                 }
2047
2048                 # Single row case
2049                 if ( !is_array( reset( $rows ) ) ) {
2050                         $rows = array( $rows );
2051                 }
2052
2053                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2054                 foreach ( $rows as $row ) {
2055                         # Delete rows which collide
2056                         if ( $uniqueIndexes ) {
2057                                 $sql = "DELETE FROM $quotedTable WHERE ";
2058                                 $first = true;
2059                                 foreach ( $uniqueIndexes as $index ) {
2060                                         if ( $first ) {
2061                                                 $first = false;
2062                                                 $sql .= '( ';
2063                                         } else {
2064                                                 $sql .= ' ) OR ( ';
2065                                         }
2066                                         if ( is_array( $index ) ) {
2067                                                 $first2 = true;
2068                                                 foreach ( $index as $col ) {
2069                                                         if ( $first2 ) {
2070                                                                 $first2 = false;
2071                                                         } else {
2072                                                                 $sql .= ' AND ';
2073                                                         }
2074                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2075                                                 }
2076                                         } else {
2077                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2078                                         }
2079                                 }
2080                                 $sql .= ' )';
2081                                 $this->query( $sql, $fname );
2082                         }
2083
2084                         # Now insert the row
2085                         $this->insert( $table, $row, $fname );
2086                 }
2087         }
2088
2089         /**
2090          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2091          * statement.
2092          *
2093          * @param string $table Table name
2094          * @param array|string $rows Row(s) to insert
2095          * @param string $fname Caller function name
2096          *
2097          * @return ResultWrapper
2098          */
2099         protected function nativeReplace( $table, $rows, $fname ) {
2100                 $table = $this->tableName( $table );
2101
2102                 # Single row case
2103                 if ( !is_array( reset( $rows ) ) ) {
2104                         $rows = array( $rows );
2105                 }
2106
2107                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2108                 $first = true;
2109
2110                 foreach ( $rows as $row ) {
2111                         if ( $first ) {
2112                                 $first = false;
2113                         } else {
2114                                 $sql .= ',';
2115                         }
2116
2117                         $sql .= '(' . $this->makeList( $row ) . ')';
2118                 }
2119
2120                 return $this->query( $sql, $fname );
2121         }
2122
2123         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2124                 $fname = __METHOD__
2125         ) {
2126                 if ( !count( $rows ) ) {
2127                         return true; // nothing to do
2128                 }
2129
2130                 if ( !is_array( reset( $rows ) ) ) {
2131                         $rows = array( $rows );
2132                 }
2133
2134                 if ( count( $uniqueIndexes ) ) {
2135                         $clauses = array(); // list WHERE clauses that each identify a single row
2136                         foreach ( $rows as $row ) {
2137                                 foreach ( $uniqueIndexes as $index ) {
2138                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2139                                         $rowKey = array(); // unique key to this row
2140                                         foreach ( $index as $column ) {
2141                                                 $rowKey[$column] = $row[$column];
2142                                         }
2143                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2144                                 }
2145                         }
2146                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2147                 } else {
2148                         $where = false;
2149                 }
2150
2151                 $useTrx = !$this->mTrxLevel;
2152                 if ( $useTrx ) {
2153                         $this->begin( $fname );
2154                 }
2155                 try {
2156                         # Update any existing conflicting row(s)
2157                         if ( $where !== false ) {
2158                                 $ok = $this->update( $table, $set, $where, $fname );
2159                         } else {
2160                                 $ok = true;
2161                         }
2162                         # Now insert any non-conflicting row(s)
2163                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2164                 } catch ( Exception $e ) {
2165                         if ( $useTrx ) {
2166                                 $this->rollback( $fname );
2167                         }
2168                         throw $e;
2169                 }
2170                 if ( $useTrx ) {
2171                         $this->commit( $fname );
2172                 }
2173
2174                 return $ok;
2175         }
2176
2177         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2178                 $fname = __METHOD__
2179         ) {
2180                 if ( !$conds ) {
2181                         throw new DBUnexpectedError( $this,
2182                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2183                 }
2184
2185                 $delTable = $this->tableName( $delTable );
2186                 $joinTable = $this->tableName( $joinTable );
2187                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2188                 if ( $conds != '*' ) {
2189                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2190                 }
2191                 $sql .= ')';
2192
2193                 $this->query( $sql, $fname );
2194         }
2195
2196         /**
2197          * Returns the size of a text field, or -1 for "unlimited"
2198          *
2199          * @param string $table
2200          * @param string $field
2201          * @return int
2202          */
2203         public function textFieldSize( $table, $field ) {
2204                 $table = $this->tableName( $table );
2205                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2206                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2207                 $row = $this->fetchObject( $res );
2208
2209                 $m = array();
2210
2211                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2212                         $size = $m[1];
2213                 } else {
2214                         $size = -1;
2215                 }
2216
2217                 return $size;
2218         }
2219
2220         /**
2221          * A string to insert into queries to show that they're low-priority, like
2222          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2223          * string and nothing bad should happen.
2224          *
2225          * @return string Returns the text of the low priority option if it is
2226          *   supported, or a blank string otherwise
2227          */
2228         public function lowPriorityOption() {
2229                 return '';
2230         }
2231
2232         public function delete( $table, $conds, $fname = __METHOD__ ) {
2233                 if ( !$conds ) {
2234                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2235                 }
2236
2237                 $table = $this->tableName( $table );
2238                 $sql = "DELETE FROM $table";
2239
2240                 if ( $conds != '*' ) {
2241                         if ( is_array( $conds ) ) {
2242                                 $conds = $this->makeList( $conds, LIST_AND );
2243                         }
2244                         $sql .= ' WHERE ' . $conds;
2245                 }
2246
2247                 return $this->query( $sql, $fname );
2248         }
2249
2250         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2251                 $fname = __METHOD__,
2252                 $insertOptions = array(), $selectOptions = array()
2253         ) {
2254                 $destTable = $this->tableName( $destTable );
2255
2256                 if ( !is_array( $insertOptions ) ) {
2257                         $insertOptions = array( $insertOptions );
2258                 }
2259
2260                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2261
2262                 if ( !is_array( $selectOptions ) ) {
2263                         $selectOptions = array( $selectOptions );
2264                 }
2265
2266                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2267
2268                 if ( is_array( $srcTable ) ) {
2269                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2270                 } else {
2271                         $srcTable = $this->tableName( $srcTable );
2272                 }
2273
2274                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2275                         " SELECT $startOpts " . implode( ',', $varMap ) .
2276                         " FROM $srcTable $useIndex ";
2277
2278                 if ( $conds != '*' ) {
2279                         if ( is_array( $conds ) ) {
2280                                 $conds = $this->makeList( $conds, LIST_AND );
2281                         }
2282                         $sql .= " WHERE $conds";
2283                 }
2284
2285                 $sql .= " $tailOpts";
2286
2287                 return $this->query( $sql, $fname );
2288         }
2289
2290         /**
2291          * Construct a LIMIT query with optional offset. This is used for query
2292          * pages. The SQL should be adjusted so that only the first $limit rows
2293          * are returned. If $offset is provided as well, then the first $offset
2294          * rows should be discarded, and the next $limit rows should be returned.
2295          * If the result of the query is not ordered, then the rows to be returned
2296          * are theoretically arbitrary.
2297          *
2298          * $sql is expected to be a SELECT, if that makes a difference.
2299          *
2300          * The version provided by default works in MySQL and SQLite. It will very
2301          * likely need to be overridden for most other DBMSes.
2302          *
2303          * @param string $sql SQL query we will append the limit too
2304          * @param int $limit The SQL limit
2305          * @param int|bool $offset The SQL offset (default false)
2306          * @throws DBUnexpectedError
2307          * @return string
2308          */
2309         public function limitResult( $sql, $limit, $offset = false ) {
2310                 if ( !is_numeric( $limit ) ) {
2311                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2312                 }
2313
2314                 return "$sql LIMIT "
2315                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2316                         . "{$limit} ";
2317         }
2318
2319         public function unionSupportsOrderAndLimit() {
2320                 return true; // True for almost every DB supported
2321         }
2322
2323         public function unionQueries( $sqls, $all ) {
2324                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2325
2326                 return '(' . implode( $glue, $sqls ) . ')';
2327         }
2328
2329         public function conditional( $cond, $trueVal, $falseVal ) {
2330                 if ( is_array( $cond ) ) {
2331                         $cond = $this->makeList( $cond, LIST_AND );
2332                 }
2333
2334                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2335         }
2336
2337         public function strreplace( $orig, $old, $new ) {
2338                 return "REPLACE({$orig}, {$old}, {$new})";
2339         }
2340
2341         public function getServerUptime() {
2342                 return 0;
2343         }
2344
2345         public function wasDeadlock() {
2346                 return false;
2347         }
2348
2349         public function wasLockTimeout() {
2350                 return false;
2351         }
2352
2353         public function wasErrorReissuable() {
2354                 return false;
2355         }
2356
2357         public function wasReadOnlyError() {
2358                 return false;
2359         }
2360
2361         /**
2362          * Determines if the given query error was a connection drop
2363          * STUB
2364          *
2365          * @param integer|string $errno
2366          * @return bool
2367          */
2368         public function wasConnectionError( $errno ) {
2369                 return false;
2370         }
2371
2372         /**
2373          * Perform a deadlock-prone transaction.
2374          *
2375          * This function invokes a callback function to perform a set of write
2376          * queries. If a deadlock occurs during the processing, the transaction
2377          * will be rolled back and the callback function will be called again.
2378          *
2379          * Usage:
2380          *   $dbw->deadlockLoop( callback, ... );
2381          *
2382          * Extra arguments are passed through to the specified callback function.
2383          *
2384          * Returns whatever the callback function returned on its successful,
2385          * iteration, or false on error, for example if the retry limit was
2386          * reached.
2387          * @return mixed
2388          * @throws DBUnexpectedError
2389          * @throws Exception
2390          */
2391         public function deadlockLoop() {
2392                 $args = func_get_args();
2393                 $function = array_shift( $args );
2394                 $tries = self::DEADLOCK_TRIES;
2395
2396                 $this->begin( __METHOD__ );
2397
2398                 $retVal = null;
2399                 /** @var Exception $e */
2400                 $e = null;
2401                 do {
2402                         try {
2403                                 $retVal = call_user_func_array( $function, $args );
2404                                 break;
2405                         } catch ( DBQueryError $e ) {
2406                                 if ( $this->wasDeadlock() ) {
2407                                         // Retry after a randomized delay
2408                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2409                                 } else {
2410                                         // Throw the error back up
2411                                         throw $e;
2412                                 }
2413                         }
2414                 } while ( --$tries > 0 );
2415
2416                 if ( $tries <= 0 ) {
2417                         // Too many deadlocks; give up
2418                         $this->rollback( __METHOD__ );
2419                         throw $e;
2420                 } else {
2421                         $this->commit( __METHOD__ );
2422
2423                         return $retVal;
2424                 }
2425         }
2426
2427         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2428                 # Real waits are implemented in the subclass.
2429                 return 0;
2430         }
2431
2432         public function getSlavePos() {
2433                 # Stub
2434                 return false;
2435         }
2436
2437         public function getMasterPos() {
2438                 # Stub
2439                 return false;
2440         }
2441
2442         final public function onTransactionIdle( $callback ) {
2443                 $this->mTrxIdleCallbacks[] = array( $callback, wfGetCaller() );
2444                 if ( !$this->mTrxLevel ) {
2445                         $this->runOnTransactionIdleCallbacks();
2446                 }
2447         }
2448
2449         final public function onTransactionPreCommitOrIdle( $callback ) {
2450                 if ( $this->mTrxLevel ) {
2451                         $this->mTrxPreCommitCallbacks[] = array( $callback, wfGetCaller() );
2452                 } else {
2453                         $this->onTransactionIdle( $callback ); // this will trigger immediately
2454                 }
2455         }
2456
2457         /**
2458          * Actually any "on transaction idle" callbacks.
2459          *
2460          * @since 1.20
2461          */
2462         protected function runOnTransactionIdleCallbacks() {
2463                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2464
2465                 $e = $ePrior = null; // last exception
2466                 do { // callbacks may add callbacks :)
2467                         $callbacks = $this->mTrxIdleCallbacks;
2468                         $this->mTrxIdleCallbacks = array(); // recursion guard
2469                         foreach ( $callbacks as $callback ) {
2470                                 try {
2471                                         list( $phpCallback ) = $callback;
2472                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2473                                         call_user_func( $phpCallback );
2474                                         if ( $autoTrx ) {
2475                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2476                                         } else {
2477                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2478                                         }
2479                                 } catch ( Exception $e ) {
2480                                         if ( $ePrior ) {
2481                                                 MWExceptionHandler::logException( $ePrior );
2482                                         }
2483                                         $ePrior = $e;
2484                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2485                                         // their transactions are ended so other callbacks don't fail
2486                                         if ( $this->trxLevel() ) {
2487                                                 $this->rollback( __METHOD__ );
2488                                         }
2489                                 }
2490                         }
2491                 } while ( count( $this->mTrxIdleCallbacks ) );
2492
2493                 if ( $e instanceof Exception ) {
2494                         throw $e; // re-throw any last exception
2495                 }
2496         }
2497
2498         /**
2499          * Actually any "on transaction pre-commit" callbacks.
2500          *
2501          * @since 1.22
2502          */
2503         protected function runOnTransactionPreCommitCallbacks() {
2504                 $e = $ePrior = null; // last exception
2505                 do { // callbacks may add callbacks :)
2506                         $callbacks = $this->mTrxPreCommitCallbacks;
2507                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
2508                         foreach ( $callbacks as $callback ) {
2509                                 try {
2510                                         list( $phpCallback ) = $callback;
2511                                         call_user_func( $phpCallback );
2512                                 } catch ( Exception $e ) {
2513                                         if ( $ePrior ) {
2514                                                 MWExceptionHandler::logException( $ePrior );
2515                                         }
2516                                         $ePrior = $e;
2517                                 }
2518                         }
2519                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2520
2521                 if ( $e instanceof Exception ) {
2522                         throw $e; // re-throw any last exception
2523                 }
2524         }
2525
2526         final public function startAtomic( $fname = __METHOD__ ) {
2527                 if ( !$this->mTrxLevel ) {
2528                         $this->begin( $fname );
2529                         $this->mTrxAutomatic = true;
2530                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2531                         // in all changes being in one transaction to keep requests transactional.
2532                         if ( !$this->getFlag( DBO_TRX ) ) {
2533                                 $this->mTrxAutomaticAtomic = true;
2534                         }
2535                 }
2536
2537                 $this->mTrxAtomicLevels[] = $fname;
2538         }
2539
2540         final public function endAtomic( $fname = __METHOD__ ) {
2541                 if ( !$this->mTrxLevel ) {
2542                         throw new DBUnexpectedError( $this, 'No atomic transaction is open.' );
2543                 }
2544                 if ( !$this->mTrxAtomicLevels ||
2545                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2546                 ) {
2547                         throw new DBUnexpectedError( $this, 'Invalid atomic section ended.' );
2548                 }
2549
2550                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2551                         $this->commit( $fname, 'flush' );
2552                 }
2553         }
2554
2555         final public function doAtomicSection( $fname, $callback ) {
2556                 if ( !is_callable( $callback ) ) {
2557                         throw new UnexpectedValueException( "Invalid callback." );
2558                 };
2559
2560                 $this->startAtomic( $fname );
2561                 try {
2562                         call_user_func_array( $callback, array( $this, $fname ) );
2563                 } catch ( Exception $e ) {
2564                         $this->rollback( $fname );
2565                         throw $e;
2566                 }
2567                 $this->endAtomic( $fname );
2568         }
2569
2570         final public function begin( $fname = __METHOD__ ) {
2571                 if ( $this->mTrxLevel ) { // implicit commit
2572                         if ( $this->mTrxAtomicLevels ) {
2573                                 // If the current transaction was an automatic atomic one, then we definitely have
2574                                 // a problem. Same if there is any unclosed atomic level.
2575                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2576                                 throw new DBUnexpectedError(
2577                                         $this,
2578                                         "Got explicit BEGIN from $fname while atomic section(s) $levels are open."
2579                                 );
2580                         } elseif ( !$this->mTrxAutomatic ) {
2581                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
2582                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
2583                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
2584                                         " performing implicit commit!";
2585                                 wfWarn( $msg );
2586                                 wfLogDBError( $msg,
2587                                         $this->getLogContext( array(
2588                                                 'method' => __METHOD__,
2589                                                 'fname' => $fname,
2590                                         ) )
2591                                 );
2592                         } else {
2593                                 // if the transaction was automatic and has done write operations
2594                                 if ( $this->mTrxDoneWrites ) {
2595                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
2596                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
2597                                         );
2598                                 }
2599                         }
2600
2601                         $this->runOnTransactionPreCommitCallbacks();
2602                         $writeTime = $this->pendingWriteQueryDuration();
2603                         $this->doCommit( $fname );
2604                         if ( $this->mTrxDoneWrites ) {
2605                                 $this->mDoneWrites = microtime( true );
2606                                 $this->getTransactionProfiler()->transactionWritingOut(
2607                                         $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2608                         }
2609                         $this->runOnTransactionIdleCallbacks();
2610                 }
2611
2612                 # Avoid fatals if close() was called
2613                 $this->assertOpen();
2614
2615                 $this->doBegin( $fname );
2616                 $this->mTrxTimestamp = microtime( true );
2617                 $this->mTrxFname = $fname;
2618                 $this->mTrxDoneWrites = false;
2619                 $this->mTrxAutomatic = false;
2620                 $this->mTrxAutomaticAtomic = false;
2621                 $this->mTrxAtomicLevels = array();
2622                 $this->mTrxIdleCallbacks = array();
2623                 $this->mTrxPreCommitCallbacks = array();
2624                 $this->mTrxShortId = wfRandomString( 12 );
2625                 $this->mTrxWriteDuration = 0.0;
2626                 $this->mTrxWriteCallers = array();
2627                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2628                 // Get an estimate of the slave lag before then, treating estimate staleness
2629                 // as lag itself just to be safe
2630                 $status = $this->getApproximateLagStatus();
2631                 $this->mTrxSlaveLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2632         }
2633
2634         /**
2635          * Issues the BEGIN command to the database server.
2636          *
2637          * @see DatabaseBase::begin()
2638          * @param string $fname
2639          */
2640         protected function doBegin( $fname ) {
2641                 $this->query( 'BEGIN', $fname );
2642                 $this->mTrxLevel = 1;
2643         }
2644
2645         final public function commit( $fname = __METHOD__, $flush = '' ) {
2646                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2647                         // There are still atomic sections open. This cannot be ignored
2648                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2649                         throw new DBUnexpectedError(
2650                                 $this,
2651                                 "Got COMMIT while atomic sections $levels are still open"
2652                         );
2653                 }
2654
2655                 if ( $flush === 'flush' ) {
2656                         if ( !$this->mTrxLevel ) {
2657                                 return; // nothing to do
2658                         } elseif ( !$this->mTrxAutomatic ) {
2659                                 throw new DBUnexpectedError(
2660                                         $this,
2661                                         "$fname: Flushing an explicit transaction, getting out of sync!"
2662                                 );
2663                         }
2664                 } else {
2665                         if ( !$this->mTrxLevel ) {
2666                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
2667                                 return; // nothing to do
2668                         } elseif ( $this->mTrxAutomatic ) {
2669                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
2670                         }
2671                 }
2672
2673                 # Avoid fatals if close() was called
2674                 $this->assertOpen();
2675
2676                 $this->runOnTransactionPreCommitCallbacks();
2677                 $writeTime = $this->pendingWriteQueryDuration();
2678                 $this->doCommit( $fname );
2679                 if ( $this->mTrxDoneWrites ) {
2680                         $this->mDoneWrites = microtime( true );
2681                         $this->getTransactionProfiler()->transactionWritingOut(
2682                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2683                 }
2684                 $this->runOnTransactionIdleCallbacks();
2685         }
2686
2687         /**
2688          * Issues the COMMIT command to the database server.
2689          *
2690          * @see DatabaseBase::commit()
2691          * @param string $fname
2692          */
2693         protected function doCommit( $fname ) {
2694                 if ( $this->mTrxLevel ) {
2695                         $this->query( 'COMMIT', $fname );
2696                         $this->mTrxLevel = 0;
2697                 }
2698         }
2699
2700         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2701                 if ( $flush !== 'flush' ) {
2702                         if ( !$this->mTrxLevel ) {
2703                                 wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
2704                                 return; // nothing to do
2705                         }
2706                 } else {
2707                         if ( !$this->mTrxLevel ) {
2708                                 return; // nothing to do
2709                         }
2710                 }
2711
2712                 # Avoid fatals if close() was called
2713                 $this->assertOpen();
2714
2715                 $this->doRollback( $fname );
2716                 $this->mTrxIdleCallbacks = array(); // cancel
2717                 $this->mTrxPreCommitCallbacks = array(); // cancel
2718                 $this->mTrxAtomicLevels = array();
2719                 if ( $this->mTrxDoneWrites ) {
2720                         $this->getTransactionProfiler()->transactionWritingOut(
2721                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2722                 }
2723         }
2724
2725         /**
2726          * Issues the ROLLBACK command to the database server.
2727          *
2728          * @see DatabaseBase::rollback()
2729          * @param string $fname
2730          */
2731         protected function doRollback( $fname ) {
2732                 if ( $this->mTrxLevel ) {
2733                         $this->query( 'ROLLBACK', $fname, true );
2734                         $this->mTrxLevel = 0;
2735                 }
2736         }
2737
2738         /**
2739          * Creates a new table with structure copied from existing table
2740          * Note that unlike most database abstraction functions, this function does not
2741          * automatically append database prefix, because it works at a lower
2742          * abstraction level.
2743          * The table names passed to this function shall not be quoted (this
2744          * function calls addIdentifierQuotes when needed).
2745          *
2746          * @param string $oldName Name of table whose structure should be copied
2747          * @param string $newName Name of table to be created
2748          * @param bool $temporary Whether the new table should be temporary
2749          * @param string $fname Calling function name
2750          * @throws MWException
2751          * @return bool True if operation was successful
2752          */
2753         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2754                 $fname = __METHOD__
2755         ) {
2756                 throw new MWException(
2757                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2758         }
2759
2760         function listTables( $prefix = null, $fname = __METHOD__ ) {
2761                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2762         }
2763
2764         /**
2765          * Reset the views process cache set by listViews()
2766          * @since 1.22
2767          */
2768         final public function clearViewsCache() {
2769                 $this->allViews = null;
2770         }
2771
2772         /**
2773          * Lists all the VIEWs in the database
2774          *
2775          * For caching purposes the list of all views should be stored in
2776          * $this->allViews. The process cache can be cleared with clearViewsCache()
2777          *
2778          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2779          * @param string $fname Name of calling function
2780          * @throws MWException
2781          * @return array
2782          * @since 1.22
2783          */
2784         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2785                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
2786         }
2787
2788         /**
2789          * Differentiates between a TABLE and a VIEW
2790          *
2791          * @param string $name Name of the database-structure to test.
2792          * @throws MWException
2793          * @return bool
2794          * @since 1.22
2795          */
2796         public function isView( $name ) {
2797                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
2798         }
2799
2800         public function timestamp( $ts = 0 ) {
2801                 return wfTimestamp( TS_MW, $ts );
2802         }
2803
2804         public function timestampOrNull( $ts = null ) {
2805                 if ( is_null( $ts ) ) {
2806                         return null;
2807                 } else {
2808                         return $this->timestamp( $ts );
2809                 }
2810         }
2811
2812         /**
2813          * Take the result from a query, and wrap it in a ResultWrapper if
2814          * necessary. Boolean values are passed through as is, to indicate success
2815          * of write queries or failure.
2816          *
2817          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2818          * resource, and it was necessary to call this function to convert it to
2819          * a wrapper. Nowadays, raw database objects are never exposed to external
2820          * callers, so this is unnecessary in external code.
2821          *
2822          * @param bool|ResultWrapper|resource|object $result
2823          * @return bool|ResultWrapper
2824          */
2825         protected function resultObject( $result ) {
2826                 if ( !$result ) {
2827                         return false;
2828                 } elseif ( $result instanceof ResultWrapper ) {
2829                         return $result;
2830                 } elseif ( $result === true ) {
2831                         // Successful write query
2832                         return $result;
2833                 } else {
2834                         return new ResultWrapper( $this, $result );
2835                 }
2836         }
2837
2838         public function ping() {
2839                 # Stub. Not essential to override.
2840                 return true;
2841         }
2842
2843         public function getSessionLagStatus() {
2844                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2845         }
2846
2847         /**
2848          * Get the slave lag when the current transaction started
2849          *
2850          * This is useful when transactions might use snapshot isolation
2851          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2852          * is this lag plus transaction duration. If they don't, it is still
2853          * safe to be pessimistic. This returns null if there is no transaction.
2854          *
2855          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2856          * @since 1.27
2857          */
2858         public function getTransactionLagStatus() {
2859                 return $this->mTrxLevel
2860                         ? array( 'lag' => $this->mTrxSlaveLag, 'since' => $this->trxTimestamp() )
2861                         : null;
2862         }
2863
2864         /**
2865          * Get a slave lag estimate for this server
2866          *
2867          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2868          * @since 1.27
2869          */
2870         public function getApproximateLagStatus() {
2871                 return array(
2872                         'lag'   => $this->getLBInfo( 'slave' ) ? $this->getLag() : 0,
2873                         'since' => microtime( true )
2874                 );
2875         }
2876
2877         /**
2878          * Merge the result of getSessionLagStatus() for several DBs
2879          * using the most pessimistic values to estimate the lag of
2880          * any data derived from them in combination
2881          *
2882          * This is information is useful for caching modules
2883          *
2884          * @see WANObjectCache::set()
2885          * @see WANObjectCache::getWithSetCallback()
2886          *
2887          * @param IDatabase $db1
2888          * @param IDatabase ...
2889          * @return array Map of values:
2890          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
2891          *   - since: oldest UNIX timestamp of any of the DB lag estimates
2892          *   - pending: whether any of the DBs have uncommitted changes
2893          * @since 1.27
2894          */
2895         public static function getCacheSetOptions( IDatabase $db1 ) {
2896                 $res = array( 'lag' => 0, 'since' => INF, 'pending' => false );
2897                 foreach ( func_get_args() as $db ) {
2898                         /** @var IDatabase $db */
2899                         $status = $db->getSessionLagStatus();
2900                         if ( $status['lag'] === false ) {
2901                                 $res['lag'] = false;
2902                         } elseif ( $res['lag'] !== false ) {
2903                                 $res['lag'] = max( $res['lag'], $status['lag'] );
2904                         }
2905                         $res['since'] = min( $res['since'], $status['since'] );
2906                         $res['pending'] = $res['pending'] ?: $db->writesPending();
2907                 }
2908
2909                 return $res;
2910         }
2911
2912         public function getLag() {
2913                 return 0;
2914         }
2915
2916         function maxListLen() {
2917                 return 0;
2918         }
2919
2920         public function encodeBlob( $b ) {
2921                 return $b;
2922         }
2923
2924         public function decodeBlob( $b ) {
2925                 if ( $b instanceof Blob ) {
2926                         $b = $b->fetch();
2927                 }
2928                 return $b;
2929         }
2930
2931         public function setSessionOptions( array $options ) {
2932         }
2933
2934         /**
2935          * Read and execute SQL commands from a file.
2936          *
2937          * Returns true on success, error string or exception on failure (depending
2938          * on object's error ignore settings).
2939          *
2940          * @param string $filename File name to open
2941          * @param bool|callable $lineCallback Optional function called before reading each line
2942          * @param bool|callable $resultCallback Optional function called for each MySQL result
2943          * @param bool|string $fname Calling function name or false if name should be
2944          *   generated dynamically using $filename
2945          * @param bool|callable $inputCallback Optional function called for each
2946          *   complete line sent
2947          * @throws Exception|MWException
2948          * @return bool|string
2949          */
2950         public function sourceFile(
2951                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
2952         ) {
2953                 MediaWiki\suppressWarnings();
2954                 $fp = fopen( $filename, 'r' );
2955                 MediaWiki\restoreWarnings();
2956
2957                 if ( false === $fp ) {
2958                         throw new MWException( "Could not open \"{$filename}\".\n" );
2959                 }
2960
2961                 if ( !$fname ) {
2962                         $fname = __METHOD__ . "( $filename )";
2963                 }
2964
2965                 try {
2966                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
2967                 } catch ( Exception $e ) {
2968                         fclose( $fp );
2969                         throw $e;
2970                 }
2971
2972                 fclose( $fp );
2973
2974                 return $error;
2975         }
2976
2977         /**
2978          * Get the full path of a patch file. Originally based on archive()
2979          * from updaters.inc. Keep in mind this always returns a patch, as
2980          * it fails back to MySQL if no DB-specific patch can be found
2981          *
2982          * @param string $patch The name of the patch, like patch-something.sql
2983          * @return string Full path to patch file
2984          */
2985         public function patchPath( $patch ) {
2986                 global $IP;
2987
2988                 $dbType = $this->getType();
2989                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
2990                         return "$IP/maintenance/$dbType/archives/$patch";
2991                 } else {
2992                         return "$IP/maintenance/archives/$patch";
2993                 }
2994         }
2995
2996         public function setSchemaVars( $vars ) {
2997                 $this->mSchemaVars = $vars;
2998         }
2999
3000         /**
3001          * Read and execute commands from an open file handle.
3002          *
3003          * Returns true on success, error string or exception on failure (depending
3004          * on object's error ignore settings).
3005          *
3006          * @param resource $fp File handle
3007          * @param bool|callable $lineCallback Optional function called before reading each query
3008          * @param bool|callable $resultCallback Optional function called for each MySQL result
3009          * @param string $fname Calling function name
3010          * @param bool|callable $inputCallback Optional function called for each complete query sent
3011          * @return bool|string
3012          */
3013         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3014                 $fname = __METHOD__, $inputCallback = false
3015         ) {
3016                 $cmd = '';
3017
3018                 while ( !feof( $fp ) ) {
3019                         if ( $lineCallback ) {
3020                                 call_user_func( $lineCallback );
3021                         }
3022
3023                         $line = trim( fgets( $fp ) );
3024
3025                         if ( $line == '' ) {
3026                                 continue;
3027                         }
3028
3029                         if ( '-' == $line[0] && '-' == $line[1] ) {
3030                                 continue;
3031                         }
3032
3033                         if ( $cmd != '' ) {
3034                                 $cmd .= ' ';
3035                         }
3036
3037                         $done = $this->streamStatementEnd( $cmd, $line );
3038
3039                         $cmd .= "$line\n";
3040
3041                         if ( $done || feof( $fp ) ) {
3042                                 $cmd = $this->replaceVars( $cmd );
3043
3044                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3045                                         $res = $this->query( $cmd, $fname );
3046
3047                                         if ( $resultCallback ) {
3048                                                 call_user_func( $resultCallback, $res, $this );
3049                                         }
3050
3051                                         if ( false === $res ) {
3052                                                 $err = $this->lastError();
3053
3054                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3055                                         }
3056                                 }
3057                                 $cmd = '';
3058                         }
3059                 }
3060
3061                 return true;
3062         }
3063
3064         /**
3065          * Called by sourceStream() to check if we've reached a statement end
3066          *
3067          * @param string $sql SQL assembled so far
3068          * @param string $newLine New line about to be added to $sql
3069          * @return bool Whether $newLine contains end of the statement
3070          */
3071         public function streamStatementEnd( &$sql, &$newLine ) {
3072                 if ( $this->delimiter ) {
3073                         $prev = $newLine;
3074                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3075                         if ( $newLine != $prev ) {
3076                                 return true;
3077                         }
3078                 }
3079
3080                 return false;
3081         }
3082
3083         /**
3084          * Database independent variable replacement. Replaces a set of variables
3085          * in an SQL statement with their contents as given by $this->getSchemaVars().
3086          *
3087          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3088          *
3089          * - '{$var}' should be used for text and is passed through the database's
3090          *   addQuotes method.
3091          * - `{$var}` should be used for identifiers (e.g. table and database names).
3092          *   It is passed through the database's addIdentifierQuotes method which
3093          *   can be overridden if the database uses something other than backticks.
3094          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3095          *   database's tableName method.
3096          * - / *i* / passes the name that follows through the database's indexName method.
3097          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3098          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3099          *
3100          * @param string $ins SQL statement to replace variables in
3101          * @return string The new SQL statement with variables replaced
3102          */
3103         protected function replaceVars( $ins ) {
3104                 $vars = $this->getSchemaVars();
3105                 return preg_replace_callback(
3106                         '!
3107                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3108                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3109                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3110                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3111                         !x',
3112                         function ( $m ) use ( $vars ) {
3113                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3114                                 // check for both nonexistent keys *and* the empty string.
3115                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3116                                         if ( $m[1] === 'i' ) {
3117                                                 return $this->indexName( $m[2] );
3118                                         } else {
3119                                                 return $this->tableName( $m[2] );
3120                                         }
3121                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3122                                         return $this->addQuotes( $vars[$m[3]] );
3123                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3124                                         return $this->addIdentifierQuotes( $vars[$m[4]] );
3125                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3126                                         return $vars[$m[5]];
3127                                 } else {
3128                                         return $m[0];
3129                                 }
3130                         },
3131                         $ins
3132                 );
3133         }
3134
3135         /**
3136          * Get schema variables. If none have been set via setSchemaVars(), then
3137          * use some defaults from the current object.
3138          *
3139          * @return array
3140          */
3141         protected function getSchemaVars() {
3142                 if ( $this->mSchemaVars ) {
3143                         return $this->mSchemaVars;
3144                 } else {
3145                         return $this->getDefaultSchemaVars();
3146                 }
3147         }
3148
3149         /**
3150          * Get schema variables to use if none have been set via setSchemaVars().
3151          *
3152          * Override this in derived classes to provide variables for tables.sql
3153          * and SQL patch files.
3154          *
3155          * @return array
3156          */
3157         protected function getDefaultSchemaVars() {
3158                 return array();
3159         }
3160
3161         public function lockIsFree( $lockName, $method ) {
3162                 return true;
3163         }
3164
3165         public function lock( $lockName, $method, $timeout = 5 ) {
3166                 $this->mNamedLocksHeld[$lockName] = 1;
3167
3168                 return true;
3169         }
3170
3171         public function unlock( $lockName, $method ) {
3172                 unset( $this->mNamedLocksHeld[$lockName] );
3173
3174                 return true;
3175         }
3176
3177         public function getScopedLockAndFlush( $lockKey, $fname, $timeout ) {
3178                 if ( !$this->lock( $lockKey, $fname, $timeout ) ) {
3179                         return null;
3180                 }
3181
3182                 $unlocker = new ScopedCallback( function () use ( $lockKey, $fname ) {
3183                         $this->commit( __METHOD__, 'flush' );
3184                         $this->unlock( $lockKey, $fname );
3185                 } );
3186
3187                 $this->commit( __METHOD__, 'flush' );
3188
3189                 return $unlocker;
3190         }
3191
3192         public function namedLocksEnqueue() {
3193                 return false;
3194         }
3195
3196         /**
3197          * Lock specific tables
3198          *
3199          * @param array $read Array of tables to lock for read access
3200          * @param array $write Array of tables to lock for write access
3201          * @param string $method Name of caller
3202          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3203          * @return bool
3204          */
3205         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3206                 return true;
3207         }
3208
3209         /**
3210          * Unlock specific tables
3211          *
3212          * @param string $method The caller
3213          * @return bool
3214          */
3215         public function unlockTables( $method ) {
3216                 return true;
3217         }
3218
3219         /**
3220          * Delete a table
3221          * @param string $tableName
3222          * @param string $fName
3223          * @return bool|ResultWrapper
3224          * @since 1.18
3225          */
3226         public function dropTable( $tableName, $fName = __METHOD__ ) {
3227                 if ( !$this->tableExists( $tableName, $fName ) ) {
3228                         return false;
3229                 }
3230                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3231                 if ( $this->cascadingDeletes() ) {
3232                         $sql .= " CASCADE";
3233                 }
3234
3235                 return $this->query( $sql, $fName );
3236         }
3237
3238         /**
3239          * Get search engine class. All subclasses of this need to implement this
3240          * if they wish to use searching.
3241          *
3242          * @return string
3243          */
3244         public function getSearchEngine() {
3245                 return 'SearchEngineDummy';
3246         }
3247
3248         public function getInfinity() {
3249                 return 'infinity';
3250         }
3251
3252         public function encodeExpiry( $expiry ) {
3253                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3254                         ? $this->getInfinity()
3255                         : $this->timestamp( $expiry );
3256         }
3257
3258         public function decodeExpiry( $expiry, $format = TS_MW ) {
3259                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3260                         ? 'infinity'
3261                         : wfTimestamp( $format, $expiry );
3262         }
3263
3264         public function setBigSelects( $value = true ) {
3265                 // no-op
3266         }
3267
3268         public function isReadOnly() {
3269                 return ( $this->getReadOnlyReason() !== false );
3270         }
3271
3272         /**
3273          * @return string|bool Reason this DB is read-only or false if it is not
3274          */
3275         protected function getReadOnlyReason() {
3276                 $reason = $this->getLBInfo( 'readOnlyReason' );
3277
3278                 return is_string( $reason ) ? $reason : false;
3279         }
3280
3281         /**
3282          * @since 1.19
3283          * @return string
3284          */
3285         public function __toString() {
3286                 return (string)$this->mConn;
3287         }
3288
3289         /**
3290          * Run a few simple sanity checks
3291          */
3292         public function __destruct() {
3293                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3294                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3295                 }
3296                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
3297                         $callers = array();
3298                         foreach ( $this->mTrxIdleCallbacks as $callbackInfo ) {
3299                                 $callers[] = $callbackInfo[1];
3300                         }
3301                         $callers = implode( ', ', $callers );
3302                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3303                 }
3304         }
3305 }
3306
3307 /**
3308  * @since 1.27
3309  */
3310 abstract class Database extends DatabaseBase {
3311         // B/C until nothing type hints for DatabaseBase
3312         // @TODO: finish renaming DatabaseBase => Database
3313 }