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 seconds spent in write queries for the current transaction
 146          *
 147          * @var float
 148          */
 149         private $mTrxWriteDuration = 0.0;
 150
 151         /** @var IDatabase|null Lazy handle to the master DB this server replicates from */
 152         private $lazyMasterHandle;
 153
 154         /**
 155          * @since 1.21
 156          * @var resource File handle for upgrade
 157          */
 158         protected $fileHandle = null;
 159
 160         /**
 161          * @since 1.22
 162          * @var string[] Process cache of VIEWs names in the database
 163          */
 164         protected $allViews = null;
 165
 166         /** @var TransactionProfiler */
 167         protected $trxProfiler;
 168
 169         public function getServerInfo() {
 170                 return $this->getServerVersion();
 171         }
 172
 173         /**
 174          * @return string Command delimiter used by this database engine
 175          */
 176         public function getDelimiter() {
 177                 return $this->delimiter;
 178         }
 179
 180         /**
 181          * Boolean, controls output of large amounts of debug information.
 182          * @param bool|null $debug
 183          *   - true to enable debugging
 184          *   - false to disable debugging
 185          *   - omitted or null to do nothing
 186          *
 187          * @return bool|null Previous value of the flag
 188          */
 189         public function debug( $debug = null ) {
 190                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 191         }
 192
 193         public function bufferResults( $buffer = null ) {
 194                 if ( is_null( $buffer ) ) {
 195                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 196                 } else {
 197                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 198                 }
 199         }
 200
 201         /**
 202          * Turns on (false) or off (true) the automatic generation and sending
 203          * of a "we're sorry, but there has been a database error" page on
 204          * database errors. Default is on (false). When turned off, the
 205          * code should use lastErrno() and lastError() to handle the
 206          * situation as appropriate.
 207          *
 208          * Do not use this function outside of the Database classes.
 209          *
 210          * @param null|bool $ignoreErrors
 211          * @return bool The previous value of the flag.
 212          */
 213         protected function ignoreErrors( $ignoreErrors = null ) {
 214                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 215         }
 216
 217         public function trxLevel() {
 218                 return $this->mTrxLevel;
 219         }
 220
 221         public function trxTimestamp() {
 222                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 223         }
 224
 225         public function tablePrefix( $prefix = null ) {
 226                 return wfSetVar( $this->mTablePrefix, $prefix );
 227         }
 228
 229         public function dbSchema( $schema = null ) {
 230                 return wfSetVar( $this->mSchema, $schema );
 231         }
 232
 233         /**
 234          * Set the filehandle to copy write statements to.
 235          *
 236          * @param resource $fh File handle
 237          */
 238         public function setFileHandle( $fh ) {
 239                 $this->fileHandle = $fh;
 240         }
 241
 242         public function getLBInfo( $name = null ) {
 243                 if ( is_null( $name ) ) {
 244                         return $this->mLBInfo;
 245                 } else {
 246                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 247                                 return $this->mLBInfo[$name];
 248                         } else {
 249                                 return null;
 250                         }
 251                 }
 252         }
 253
 254         public function setLBInfo( $name, $value = null ) {
 255                 if ( is_null( $value ) ) {
 256                         $this->mLBInfo = $name;
 257                 } else {
 258                         $this->mLBInfo[$name] = $value;
 259                 }
 260         }
 261
 262         /**
 263          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 264          *
 265          * @param IDatabase $conn
 266          * @since 1.27
 267          */
 268         public function setLazyMasterHandle( IDatabase $conn ) {
 269                 $this->lazyMasterHandle = $conn;
 270         }
 271
 272         /**
 273          * @return IDatabase|null
 274          * @see setLazyMasterHandle()
 275          * @since 1.27
 276          */
 277         public function getLazyMasterHandle() {
 278                 return $this->lazyMasterHandle;
 279         }
 280
 281         /**
 282          * @return TransactionProfiler
 283          */
 284         protected function getTransactionProfiler() {
 285                 if ( !$this->trxProfiler ) {
 286                         $this->trxProfiler = new TransactionProfiler();
 287                 }
 288
 289                 return $this->trxProfiler;
 290         }
 291
 292         /**
 293          * @param TransactionProfiler $profiler
 294          * @since 1.27
 295          */
 296         public function setTransactionProfiler( TransactionProfiler $profiler ) {
 297                 $this->trxProfiler = $profiler;
 298         }
 299
 300         /**
 301          * Returns true if this database supports (and uses) cascading deletes
 302          *
 303          * @return bool
 304          */
 305         public function cascadingDeletes() {
 306                 return false;
 307         }
 308
 309         /**
 310          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 311          *
 312          * @return bool
 313          */
 314         public function cleanupTriggers() {
 315                 return false;
 316         }
 317
 318         /**
 319          * Returns true if this database is strict about what can be put into an IP field.
 320          * Specifically, it uses a NULL value instead of an empty string.
 321          *
 322          * @return bool
 323          */
 324         public function strictIPs() {
 325                 return false;
 326         }
 327
 328         /**
 329          * Returns true if this database uses timestamps rather than integers
 330          *
 331          * @return bool
 332          */
 333         public function realTimestamps() {
 334                 return false;
 335         }
 336
 337         public function implicitGroupby() {
 338                 return true;
 339         }
 340
 341         public function implicitOrderby() {
 342                 return true;
 343         }
 344
 345         /**
 346          * Returns true if this database can do a native search on IP columns
 347          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 348          *
 349          * @return bool
 350          */
 351         public function searchableIPs() {
 352                 return false;
 353         }
 354
 355         /**
 356          * Returns true if this database can use functional indexes
 357          *
 358          * @return bool
 359          */
 360         public function functionalIndexes() {
 361                 return false;
 362         }
 363
 364         public function lastQuery() {
 365                 return $this->mLastQuery;
 366         }
 367
 368         public function doneWrites() {
 369                 return (bool)$this->mDoneWrites;
 370         }
 371
 372         public function lastDoneWrites() {
 373                 return $this->mDoneWrites ?: false;
 374         }
 375
 376         public function writesPending() {
 377                 return $this->mTrxLevel && $this->mTrxDoneWrites;
 378         }
 379
 380         public function writesOrCallbacksPending() {
 381                 return $this->mTrxLevel && (
 382                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 383                 );
 384         }
 385
 386         public function pendingWriteQueryDuration() {
 387                 return $this->mTrxLevel ? $this->mTrxWriteDuration : false;
 388         }
 389
 390         public function isOpen() {
 391                 return $this->mOpened;
 392         }
 393
 394         public function setFlag( $flag ) {
 395                 $this->mFlags |= $flag;
 396         }
 397
 398         public function clearFlag( $flag ) {
 399                 $this->mFlags &= ~$flag;
 400         }
 401
 402         public function getFlag( $flag ) {
 403                 return !!( $this->mFlags & $flag );
 404         }
 405
 406         public function getProperty( $name ) {
 407                 return $this->$name;
 408         }
 409
 410         public function getWikiID() {
 411                 if ( $this->mTablePrefix ) {
 412                         return "{$this->mDBname}-{$this->mTablePrefix}";
 413                 } else {
 414                         return $this->mDBname;
 415                 }
 416         }
 417
 418         /**
 419          * Return a path to the DBMS-specific SQL file if it exists,
 420          * otherwise default SQL file
 421          *
 422          * @param string $filename
 423          * @return string
 424          */
 425         private function getSqlFilePath( $filename ) {
 426                 global $IP;
 427                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 428                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 429                         return $dbmsSpecificFilePath;
 430                 } else {
 431                         return "$IP/maintenance/$filename";
 432                 }
 433         }
 434
 435         /**
 436          * Return a path to the DBMS-specific schema file,
 437          * otherwise default to tables.sql
 438          *
 439          * @return string
 440          */
 441         public function getSchemaPath() {
 442                 return $this->getSqlFilePath( 'tables.sql' );
 443         }
 444
 445         /**
 446          * Return a path to the DBMS-specific update key file,
 447          * otherwise default to update-keys.sql
 448          *
 449          * @return string
 450          */
 451         public function getUpdateKeysPath() {
 452                 return $this->getSqlFilePath( 'update-keys.sql' );
 453         }
 454
 455         /**
 456          * Get information about an index into an object
 457          * @param string $table Table name
 458          * @param string $index Index name
 459          * @param string $fname Calling function name
 460          * @return mixed Database-specific index description class or false if the index does not exist
 461          */
 462         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 463
 464         /**
 465          * Wrapper for addslashes()
 466          *
 467          * @param string $s String to be slashed.
 468          * @return string Slashed string.
 469          */
 470         abstract function strencode( $s );
 471
 472         /**
 473          * Constructor.
 474          *
 475          * FIXME: It is possible to construct a Database object with no associated
 476          * connection object, by specifying no parameters to __construct(). This
 477          * feature is deprecated and should be removed.
 478          *
 479          * DatabaseBase subclasses should not be constructed directly in external
 480          * code. DatabaseBase::factory() should be used instead.
 481          *
 482          * @param array $params Parameters passed from DatabaseBase::factory()
 483          */
 484         function __construct( array $params ) {
 485                 global $wgDBprefix, $wgDBmwschema, $wgCommandLineMode;
 486
 487                 $this->srvCache = ObjectCache::getLocalServerInstance( 'hash' );
 488
 489                 $server = $params['host'];
 490                 $user = $params['user'];
 491                 $password = $params['password'];
 492                 $dbName = $params['dbname'];
 493                 $flags = $params['flags'];
 494                 $tablePrefix = $params['tablePrefix'];
 495                 $schema = $params['schema'];
 496                 $foreign = $params['foreign'];
 497
 498                 $this->mFlags = $flags;
 499                 if ( $this->mFlags & DBO_DEFAULT ) {
 500                         if ( $wgCommandLineMode ) {
 501                                 $this->mFlags &= ~DBO_TRX;
 502                         } else {
 503                                 $this->mFlags |= DBO_TRX;
 504                         }
 505                 }
 506
 507                 $this->mSessionVars = $params['variables'];
 508
 509                 /** Get the default table prefix*/
 510                 if ( $tablePrefix === 'get from global' ) {
 511                         $this->mTablePrefix = $wgDBprefix;
 512                 } else {
 513                         $this->mTablePrefix = $tablePrefix;
 514                 }
 515
 516                 /** Get the database schema*/
 517                 if ( $schema === 'get from global' ) {
 518                         $this->mSchema = $wgDBmwschema;
 519                 } else {
 520                         $this->mSchema = $schema;
 521                 }
 522
 523                 $this->mForeign = $foreign;
 524
 525                 if ( isset( $params['trxProfiler'] ) ) {
 526                         $this->trxProfiler = $params['trxProfiler']; // override
 527                 }
 528
 529                 if ( $user ) {
 530                         $this->open( $server, $user, $password, $dbName );
 531                 }
 532         }
 533
 534         /**
 535          * Called by serialize. Throw an exception when DB connection is serialized.
 536          * This causes problems on some database engines because the connection is
 537          * not restored on unserialize.
 538          */
 539         public function __sleep() {
 540                 throw new MWException( 'Database serialization may cause problems, since ' .
 541                         'the connection is not restored on wakeup.' );
 542         }
 543
 544         /**
 545          * Given a DB type, construct the name of the appropriate child class of
 546          * DatabaseBase. This is designed to replace all of the manual stuff like:
 547          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 548          * as well as validate against the canonical list of DB types we have
 549          *
 550          * This factory function is mostly useful for when you need to connect to a
 551          * database other than the MediaWiki default (such as for external auth,
 552          * an extension, et cetera). Do not use this to connect to the MediaWiki
 553          * database. Example uses in core:
 554          * @see LoadBalancer::reallyOpenConnection()
 555          * @see ForeignDBRepo::getMasterDB()
 556          * @see WebInstallerDBConnect::execute()
 557          *
 558          * @since 1.18
 559          *
 560          * @param string $dbType A possible DB type
 561          * @param array $p An array of options to pass to the constructor.
 562          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 563          * @throws MWException If the database driver or extension cannot be found
 564          * @return DatabaseBase|null DatabaseBase subclass or null
 565          */
 566         final public static function factory( $dbType, $p = array() ) {
 567                 $canonicalDBTypes = array(
 568                         'mysql' => array( 'mysqli', 'mysql' ),
 569                         'postgres' => array(),
 570                         'sqlite' => array(),
 571                         'oracle' => array(),
 572                         'mssql' => array(),
 573                 );
 574
 575                 $driver = false;
 576                 $dbType = strtolower( $dbType );
 577                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 578                         $possibleDrivers = $canonicalDBTypes[$dbType];
 579                         if ( !empty( $p['driver'] ) ) {
 580                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 581                                         $driver = $p['driver'];
 582                                 } else {
 583                                         throw new MWException( __METHOD__ .
 584                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 585                                 }
 586                         } else {
 587                                 foreach ( $possibleDrivers as $posDriver ) {
 588                                         if ( extension_loaded( $posDriver ) ) {
 589                                                 $driver = $posDriver;
 590                                                 break;
 591                                         }
 592                                 }
 593                         }
 594                 } else {
 595                         $driver = $dbType;
 596                 }
 597                 if ( $driver === false ) {
 598                         throw new MWException( __METHOD__ .
 599                                 " no viable database extension found for type '$dbType'" );
 600                 }
 601
 602                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 603                 // and everything else doesn't use a schema (e.g. null)
 604                 // Although postgres and oracle support schemas, we don't use them (yet)
 605                 // to maintain backwards compatibility
 606                 $defaultSchemas = array(
 607                         'mssql' => 'get from global',
 608                 );
 609
 610                 $class = 'Database' . ucfirst( $driver );
 611                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 612                         // Resolve some defaults for b/c
 613                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 614                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 615                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 616                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 617                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 618                         $p['variables'] = isset( $p['variables'] ) ? $p['variables'] : array();
 619                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 620                         if ( !isset( $p['schema'] ) ) {
 621                                 $p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
 622                         }
 623                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 624
 625                         return new $class( $p );
 626                 } else {
 627                         return null;
 628                 }
 629         }
 630
 631         protected function installErrorHandler() {
 632                 $this->mPHPError = false;
 633                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 634                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 635         }
 636
 637         /**
 638          * @return bool|string
 639          */
 640         protected function restoreErrorHandler() {
 641                 restore_error_handler();
 642                 if ( $this->htmlErrors !== false ) {
 643                         ini_set( 'html_errors', $this->htmlErrors );
 644                 }
 645                 if ( $this->mPHPError ) {
 646                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 647                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 648
 649                         return $error;
 650                 } else {
 651                         return false;
 652                 }
 653         }
 654
 655         /**
 656          * @param int $errno
 657          * @param string $errstr
 658          */
 659         public function connectionErrorHandler( $errno, $errstr ) {
 660                 $this->mPHPError = $errstr;
 661         }
 662
 663         /**
 664          * Create a log context to pass to wfLogDBError or other logging functions.
 665          *
 666          * @param array $extras Additional data to add to context
 667          * @return array
 668          */
 669         protected function getLogContext( array $extras = array() ) {
 670                 return array_merge(
 671                         array(
 672                                 'db_server' => $this->mServer,
 673                                 'db_name' => $this->mDBname,
 674                                 'db_user' => $this->mUser,
 675                         ),
 676                         $extras
 677                 );
 678         }
 679
 680         public function close() {
 681                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 682                         throw new MWException( "Transaction idle callbacks still pending." );
 683                 }
 684                 if ( $this->mConn ) {
 685                         if ( $this->trxLevel() ) {
 686                                 if ( !$this->mTrxAutomatic ) {
 687                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 688                                                 " performing implicit commit before closing connection!" );
 689                                 }
 690
 691                                 $this->commit( __METHOD__, 'flush' );
 692                         }
 693
 694                         $closed = $this->closeConnection();
 695                         $this->mConn = false;
 696                 } else {
 697                         $closed = true;
 698                 }
 699                 $this->mOpened = false;
 700
 701                 return $closed;
 702         }
 703
 704         /**
 705          * Make sure isOpen() returns true as a sanity check
 706          *
 707          * @throws DBUnexpectedError
 708          */
 709         protected function assertOpen() {
 710                 if ( !$this->isOpen() ) {
 711                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
 712                 }
 713         }
 714
 715         /**
 716          * Closes underlying database connection
 717          * @since 1.20
 718          * @return bool Whether connection was closed successfully
 719          */
 720         abstract protected function closeConnection();
 721
 722         function reportConnectionError( $error = 'Unknown error' ) {
 723                 $myError = $this->lastError();
 724                 if ( $myError ) {
 725                         $error = $myError;
 726                 }
 727
 728                 # New method
 729                 throw new DBConnectionError( $this, $error );
 730         }
 731
 732         /**
 733          * The DBMS-dependent part of query()
 734          *
 735          * @param string $sql SQL query.
 736          * @return ResultWrapper|bool Result object to feed to fetchObject,
 737          *   fetchRow, ...; or false on failure
 738          */
 739         abstract protected function doQuery( $sql );
 740
 741         /**
 742          * Determine whether a query writes to the DB.
 743          * Should return true if unsure.
 744          *
 745          * @param string $sql
 746          * @return bool
 747          */
 748         protected function isWriteQuery( $sql ) {
 749                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 750         }
 751
 752         /**
 753          * Determine whether a SQL statement is sensitive to isolation level.
 754          * A SQL statement is considered transactable if its result could vary
 755          * depending on the transaction isolation level. Operational commands
 756          * such as 'SET' and 'SHOW' are not considered to be transactable.
 757          *
 758          * @param string $sql
 759          * @return bool
 760          */
 761         protected function isTransactableQuery( $sql ) {
 762                 $verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
 763                 return !in_array( $verb, array( 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ) );
 764         }
 765
 766         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 767                 global $wgUser;
 768
 769                 $this->mLastQuery = $sql;
 770
 771                 $isWriteQuery = $this->isWriteQuery( $sql );
 772                 if ( $isWriteQuery ) {
 773                         $reason = $this->getReadOnlyReason();
 774                         if ( $reason !== false ) {
 775                                 throw new DBReadOnlyError( $this, "Database is read-only: $reason" );
 776                         }
 777                         # Set a flag indicating that writes have been done
 778                         $this->mDoneWrites = microtime( true );
 779                 }
 780
 781                 # Add a comment for easy SHOW PROCESSLIST interpretation
 782                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 783                         $userName = $wgUser->getName();
 784                         if ( mb_strlen( $userName ) > 15 ) {
 785                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 786                         }
 787                         $userName = str_replace( '/', '', $userName );
 788                 } else {
 789                         $userName = '';
 790                 }
 791
 792                 // Add trace comment to the begin of the sql string, right after the operator.
 793                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 794                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 795
 796                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX ) && $this->isTransactableQuery( $sql ) ) {
 797                         $this->begin( __METHOD__ . " ($fname)" );
 798                         $this->mTrxAutomatic = true;
 799                 }
 800
 801                 # Keep track of whether the transaction has write queries pending
 802                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWriteQuery ) {
 803                         $this->mTrxDoneWrites = true;
 804                         $this->getTransactionProfiler()->transactionWritingIn(
 805                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
 806                 }
 807
 808                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 809                 # generalizeSQL will probably cut down the query to reasonable
 810                 # logging size most of the time. The substr is really just a sanity check.
 811                 if ( $isMaster ) {
 812                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 813                         $totalProf = 'DatabaseBase::query-master';
 814                 } else {
 815                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 816                         $totalProf = 'DatabaseBase::query';
 817                 }
 818                 # Include query transaction state
 819                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
 820
 821                 $profiler = Profiler::instance();
 822                 if ( !$profiler instanceof ProfilerStub ) {
 823                         $totalProfSection = $profiler->scopedProfileIn( $totalProf );
 824                         $queryProfSection = $profiler->scopedProfileIn( $queryProf );
 825                 }
 826
 827                 if ( $this->debug() ) {
 828                         wfDebugLog( 'queries', sprintf( "%s: %s", $this->mDBname, $commentedSql ) );
 829                 }
 830
 831                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 832
 833                 # Avoid fatals if close() was called
 834                 $this->assertOpen();
 835
 836                 # Do the query and handle errors
 837                 $startTime = microtime( true );
 838                 $ret = $this->doQuery( $commentedSql );
 839                 $queryRuntime = microtime( true ) - $startTime;
 840                 # Log the query time and feed it into the DB trx profiler
 841                 $this->getTransactionProfiler()->recordQueryCompletion(
 842                         $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
 843
 844                 MWDebug::queryTime( $queryId );
 845
 846                 # Try reconnecting if the connection was lost
 847                 if ( false === $ret && $this->wasErrorReissuable() ) {
 848                         # Transaction is gone, like it or not
 849                         $hadTrx = $this->mTrxLevel; // possible lost transaction
 850                         $this->mTrxLevel = 0;
 851                         $this->mTrxIdleCallbacks = array(); // bug 65263
 852                         $this->mTrxPreCommitCallbacks = array(); // bug 65263
 853                         wfDebug( "Connection lost, reconnecting...\n" );
 854                         # Stash the last error values since ping() might clear them
 855                         $lastError = $this->lastError();
 856                         $lastErrno = $this->lastErrno();
 857                         if ( $this->ping() ) {
 858                                 wfDebug( "Reconnected\n" );
 859                                 $server = $this->getServer();
 860                                 $msg = __METHOD__ . ": lost connection to $server; reconnected";
 861                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
 862
 863                                 if ( $hadTrx ) {
 864                                         # Leave $ret as false and let an error be reported.
 865                                         # Callers may catch the exception and continue to use the DB.
 866                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
 867                                 } else {
 868                                         # Should be safe to silently retry (no trx and thus no callbacks)
 869                                         $startTime = microtime( true );
 870                                         $ret = $this->doQuery( $commentedSql );
 871                                         $queryRuntime = microtime( true ) - $startTime;
 872                                         # Log the query time and feed it into the DB trx profiler
 873                                         $this->getTransactionProfiler()->recordQueryCompletion(
 874                                                 $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
 875                                 }
 876                         } else {
 877                                 wfDebug( "Failed\n" );
 878                         }
 879                 }
 880
 881                 if ( false === $ret ) {
 882                         $this->reportQueryError(
 883                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 884                 }
 885
 886                 $res = $this->resultObject( $ret );
 887
 888                 // Destroy profile sections in the opposite order to their creation
 889                 ScopedCallback::consume( $queryProfSection );
 890                 ScopedCallback::consume( $totalProfSection );
 891
 892                 if ( $isWriteQuery && $this->mTrxLevel ) {
 893                         $this->mTrxWriteDuration += $queryRuntime;
 894                 }
 895
 896                 return $res;
 897         }
 898
 899         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 900                 if ( $this->ignoreErrors() || $tempIgnore ) {
 901                         wfDebug( "SQL ERROR (ignored): $error\n" );
 902                 } else {
 903                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
 904                         wfLogDBError(
 905                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
 906                                 $this->getLogContext( array(
 907                                         'method' => __METHOD__,
 908                                         'errno' => $errno,
 909                                         'error' => $error,
 910                                         'sql1line' => $sql1line,
 911                                         'fname' => $fname,
 912                                 ) )
 913                         );
 914                         wfDebug( "SQL ERROR: " . $error . "\n" );
 915                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 916                 }
 917         }
 918
 919         /**
 920          * Intended to be compatible with the PEAR::DB wrapper functions.
 921          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 922          *
 923          * ? = scalar value, quoted as necessary
 924          * ! = raw SQL bit (a function for instance)
 925          * & = filename; reads the file and inserts as a blob
 926          *     (we don't use this though...)
 927          *
 928          * @param string $sql
 929          * @param string $func
 930          *
 931          * @return array
 932          */
 933         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 934                 /* MySQL doesn't support prepared statements (yet), so just
 935                  * pack up the query for reference. We'll manually replace
 936                  * the bits later.
 937                  */
 938                 return array( 'query' => $sql, 'func' => $func );
 939         }
 940
 941         /**
 942          * Free a prepared query, generated by prepare().
 943          * @param string $prepared
 944          */
 945         protected function freePrepared( $prepared ) {
 946                 /* No-op by default */
 947         }
 948
 949         /**
 950          * Execute a prepared query with the various arguments
 951          * @param string $prepared The prepared sql
 952          * @param mixed $args Either an array here, or put scalars as varargs
 953          *
 954          * @return ResultWrapper
 955          */
 956         public function execute( $prepared, $args = null ) {
 957                 if ( !is_array( $args ) ) {
 958                         # Pull the var args
 959                         $args = func_get_args();
 960                         array_shift( $args );
 961                 }
 962
 963                 $sql = $this->fillPrepared( $prepared['query'], $args );
 964
 965                 return $this->query( $sql, $prepared['func'] );
 966         }
 967
 968         /**
 969          * For faking prepared SQL statements on DBs that don't support it directly.
 970          *
 971          * @param string $preparedQuery A 'preparable' SQL statement
 972          * @param array $args Array of Arguments to fill it with
 973          * @return string Executable SQL
 974          */
 975         public function fillPrepared( $preparedQuery, $args ) {
 976                 reset( $args );
 977                 $this->preparedArgs =& $args;
 978
 979                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 980                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 981         }
 982
 983         /**
 984          * preg_callback func for fillPrepared()
 985          * The arguments should be in $this->preparedArgs and must not be touched
 986          * while we're doing this.
 987          *
 988          * @param array $matches
 989          * @throws DBUnexpectedError
 990          * @return string
 991          */
 992         protected function fillPreparedArg( $matches ) {
 993                 switch ( $matches[1] ) {
 994                         case '\\?':
 995                                 return '?';
 996                         case '\\!':
 997                                 return '!';
 998                         case '\\&':
 999                                 return '&';
1000                 }
1001
1002                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1003
1004                 switch ( $matches[1] ) {
1005                         case '?':
1006                                 return $this->addQuotes( $arg );
1007                         case '!':
1008                                 return $arg;
1009                         case '&':
1010                                 # return $this->addQuotes( file_get_contents( $arg ) );
1011                                 throw new DBUnexpectedError(
1012                                         $this,
1013                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1014                                 );
1015                         default:
1016                                 throw new DBUnexpectedError(
1017                                         $this,
1018                                         'Received invalid match. This should never happen!'
1019                                 );
1020                 }
1021         }
1022
1023         public function freeResult( $res ) {
1024         }
1025
1026         public function selectField(
1027                 $table, $var, $cond = '', $fname = __METHOD__, $options = array()
1028         ) {
1029                 if ( $var === '*' ) { // sanity
1030                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1031                 }
1032
1033                 if ( !is_array( $options ) ) {
1034                         $options = array( $options );
1035                 }
1036
1037                 $options['LIMIT'] = 1;
1038
1039                 $res = $this->select( $table, $var, $cond, $fname, $options );
1040                 if ( $res === false || !$this->numRows( $res ) ) {
1041                         return false;
1042                 }
1043
1044                 $row = $this->fetchRow( $res );
1045
1046                 if ( $row !== false ) {
1047                         return reset( $row );
1048                 } else {
1049                         return false;
1050                 }
1051         }
1052
1053         public function selectFieldValues(
1054                 $table, $var, $cond = '', $fname = __METHOD__, $options = array(), $join_conds = array()
1055         ) {
1056                 if ( $var === '*' ) { // sanity
1057                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1058                 }
1059
1060                 if ( !is_array( $options ) ) {
1061                         $options = array( $options );
1062                 }
1063
1064                 $res = $this->select( $table, $var, $cond, $fname, $options, $join_conds );
1065                 if ( $res === false ) {
1066                         return false;
1067                 }
1068
1069                 $values = array();
1070                 foreach ( $res as $row ) {
1071                         $values[] = $row->$var;
1072                 }
1073
1074                 return $values;
1075         }
1076
1077         /**
1078          * Returns an optional USE INDEX clause to go after the table, and a
1079          * string to go at the end of the query.
1080          *
1081          * @param array $options Associative array of options to be turned into
1082          *   an SQL query, valid keys are listed in the function.
1083          * @return array
1084          * @see DatabaseBase::select()
1085          */
1086         public function makeSelectOptions( $options ) {
1087                 $preLimitTail = $postLimitTail = '';
1088                 $startOpts = '';
1089
1090                 $noKeyOptions = array();
1091
1092                 foreach ( $options as $key => $option ) {
1093                         if ( is_numeric( $key ) ) {
1094                                 $noKeyOptions[$option] = true;
1095                         }
1096                 }
1097
1098                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1099
1100                 $preLimitTail .= $this->makeOrderBy( $options );
1101
1102                 // if (isset($options['LIMIT'])) {
1103                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1104                 //              isset($options['OFFSET']) ? $options['OFFSET']
1105                 //              : false);
1106                 // }
1107
1108                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1109                         $postLimitTail .= ' FOR UPDATE';
1110                 }
1111
1112                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1113                         $postLimitTail .= ' LOCK IN SHARE MODE';
1114                 }
1115
1116                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1117                         $startOpts .= 'DISTINCT';
1118                 }
1119
1120                 # Various MySQL extensions
1121                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1122                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1123                 }
1124
1125                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1126                         $startOpts .= ' HIGH_PRIORITY';
1127                 }
1128
1129                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1130                         $startOpts .= ' SQL_BIG_RESULT';
1131                 }
1132
1133                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1134                         $startOpts .= ' SQL_BUFFER_RESULT';
1135                 }
1136
1137                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1138                         $startOpts .= ' SQL_SMALL_RESULT';
1139                 }
1140
1141                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1142                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1143                 }
1144
1145                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1146                         $startOpts .= ' SQL_CACHE';
1147                 }
1148
1149                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1150                         $startOpts .= ' SQL_NO_CACHE';
1151                 }
1152
1153                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1154                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1155                 } else {
1156                         $useIndex = '';
1157                 }
1158
1159                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1160         }
1161
1162         /**
1163          * Returns an optional GROUP BY with an optional HAVING
1164          *
1165          * @param array $options Associative array of options
1166          * @return string
1167          * @see DatabaseBase::select()
1168          * @since 1.21
1169          */
1170         public function makeGroupByWithHaving( $options ) {
1171                 $sql = '';
1172                 if ( isset( $options['GROUP BY'] ) ) {
1173                         $gb = is_array( $options['GROUP BY'] )
1174                                 ? implode( ',', $options['GROUP BY'] )
1175                                 : $options['GROUP BY'];
1176                         $sql .= ' GROUP BY ' . $gb;
1177                 }
1178                 if ( isset( $options['HAVING'] ) ) {
1179                         $having = is_array( $options['HAVING'] )
1180                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1181                                 : $options['HAVING'];
1182                         $sql .= ' HAVING ' . $having;
1183                 }
1184
1185                 return $sql;
1186         }
1187
1188         /**
1189          * Returns an optional ORDER BY
1190          *
1191          * @param array $options Associative array of options
1192          * @return string
1193          * @see DatabaseBase::select()
1194          * @since 1.21
1195          */
1196         public function makeOrderBy( $options ) {
1197                 if ( isset( $options['ORDER BY'] ) ) {
1198                         $ob = is_array( $options['ORDER BY'] )
1199                                 ? implode( ',', $options['ORDER BY'] )
1200                                 : $options['ORDER BY'];
1201
1202                         return ' ORDER BY ' . $ob;
1203                 }
1204
1205                 return '';
1206         }
1207
1208         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1209                 $options = array(), $join_conds = array() ) {
1210                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1211
1212                 return $this->query( $sql, $fname );
1213         }
1214
1215         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1216                 $options = array(), $join_conds = array()
1217         ) {
1218                 if ( is_array( $vars ) ) {
1219                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1220                 }
1221
1222                 $options = (array)$options;
1223                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1224                         ? $options['USE INDEX']
1225                         : array();
1226
1227                 if ( is_array( $table ) ) {
1228                         $from = ' FROM ' .
1229                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1230                 } elseif ( $table != '' ) {
1231                         if ( $table[0] == ' ' ) {
1232                                 $from = ' FROM ' . $table;
1233                         } else {
1234                                 $from = ' FROM ' .
1235                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1236                         }
1237                 } else {
1238                         $from = '';
1239                 }
1240
1241                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1242                         $this->makeSelectOptions( $options );
1243
1244                 if ( !empty( $conds ) ) {
1245                         if ( is_array( $conds ) ) {
1246                                 $conds = $this->makeList( $conds, LIST_AND );
1247                         }
1248                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1249                 } else {
1250                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1251                 }
1252
1253                 if ( isset( $options['LIMIT'] ) ) {
1254                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1255                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1256                 }
1257                 $sql = "$sql $postLimitTail";
1258
1259                 if ( isset( $options['EXPLAIN'] ) ) {
1260                         $sql = 'EXPLAIN ' . $sql;
1261                 }
1262
1263                 return $sql;
1264         }
1265
1266         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1267                 $options = array(), $join_conds = array()
1268         ) {
1269                 $options = (array)$options;
1270                 $options['LIMIT'] = 1;
1271                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1272
1273                 if ( $res === false ) {
1274                         return false;
1275                 }
1276
1277                 if ( !$this->numRows( $res ) ) {
1278                         return false;
1279                 }
1280
1281                 $obj = $this->fetchObject( $res );
1282
1283                 return $obj;
1284         }
1285
1286         public function estimateRowCount(
1287                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
1288         ) {
1289                 $rows = 0;
1290                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1291
1292                 if ( $res ) {
1293                         $row = $this->fetchRow( $res );
1294                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1295                 }
1296
1297                 return $rows;
1298         }
1299
1300         public function selectRowCount(
1301                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = array(), $join_conds = array()
1302         ) {
1303                 $rows = 0;
1304                 $sql = $this->selectSQLText( $tables, '1', $conds, $fname, $options, $join_conds );
1305                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
1306
1307                 if ( $res ) {
1308                         $row = $this->fetchRow( $res );
1309                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1310                 }
1311
1312                 return $rows;
1313         }
1314
1315         /**
1316          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1317          * It's only slightly flawed. Don't use for anything important.
1318          *
1319          * @param string $sql A SQL Query
1320          *
1321          * @return string
1322          */
1323         protected static function generalizeSQL( $sql ) {
1324                 # This does the same as the regexp below would do, but in such a way
1325                 # as to avoid crashing php on some large strings.
1326                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1327
1328                 $sql = str_replace( "\\\\", '', $sql );
1329                 $sql = str_replace( "\\'", '', $sql );
1330                 $sql = str_replace( "\\\"", '', $sql );
1331                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1332                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1333
1334                 # All newlines, tabs, etc replaced by single space
1335                 $sql = preg_replace( '/\s+/', ' ', $sql );
1336
1337                 # All numbers => N,
1338                 # except the ones surrounded by characters, e.g. l10n
1339                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1340                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1341
1342                 return $sql;
1343         }
1344
1345         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1346                 $info = $this->fieldInfo( $table, $field );
1347
1348                 return (bool)$info;
1349         }
1350
1351         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1352                 if ( !$this->tableExists( $table ) ) {
1353                         return null;
1354                 }
1355
1356                 $info = $this->indexInfo( $table, $index, $fname );
1357                 if ( is_null( $info ) ) {
1358                         return null;
1359                 } else {
1360                         return $info !== false;
1361                 }
1362         }
1363
1364         public function tableExists( $table, $fname = __METHOD__ ) {
1365                 $table = $this->tableName( $table );
1366                 $old = $this->ignoreErrors( true );
1367                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1368                 $this->ignoreErrors( $old );
1369
1370                 return (bool)$res;
1371         }
1372
1373         public function indexUnique( $table, $index ) {
1374                 $indexInfo = $this->indexInfo( $table, $index );
1375
1376                 if ( !$indexInfo ) {
1377                         return null;
1378                 }
1379
1380                 return !$indexInfo[0]->Non_unique;
1381         }
1382
1383         /**
1384          * Helper for DatabaseBase::insert().
1385          *
1386          * @param array $options
1387          * @return string
1388          */
1389         protected function makeInsertOptions( $options ) {
1390                 return implode( ' ', $options );
1391         }
1392
1393         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
1394                 # No rows to insert, easy just return now
1395                 if ( !count( $a ) ) {
1396                         return true;
1397                 }
1398
1399                 $table = $this->tableName( $table );
1400
1401                 if ( !is_array( $options ) ) {
1402                         $options = array( $options );
1403                 }
1404
1405                 $fh = null;
1406                 if ( isset( $options['fileHandle'] ) ) {
1407                         $fh = $options['fileHandle'];
1408                 }
1409                 $options = $this->makeInsertOptions( $options );
1410
1411                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1412                         $multi = true;
1413                         $keys = array_keys( $a[0] );
1414                 } else {
1415                         $multi = false;
1416                         $keys = array_keys( $a );
1417                 }
1418
1419                 $sql = 'INSERT ' . $options .
1420                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1421
1422                 if ( $multi ) {
1423                         $first = true;
1424                         foreach ( $a as $row ) {
1425                                 if ( $first ) {
1426                                         $first = false;
1427                                 } else {
1428                                         $sql .= ',';
1429                                 }
1430                                 $sql .= '(' . $this->makeList( $row ) . ')';
1431                         }
1432                 } else {
1433                         $sql .= '(' . $this->makeList( $a ) . ')';
1434                 }
1435
1436                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1437                         return false;
1438                 } elseif ( $fh !== null ) {
1439                         return true;
1440                 }
1441
1442                 return (bool)$this->query( $sql, $fname );
1443         }
1444
1445         /**
1446          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
1447          *
1448          * @param array $options
1449          * @return array
1450          */
1451         protected function makeUpdateOptionsArray( $options ) {
1452                 if ( !is_array( $options ) ) {
1453                         $options = array( $options );
1454                 }
1455
1456                 $opts = array();
1457
1458                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1459                         $opts[] = $this->lowPriorityOption();
1460                 }
1461
1462                 if ( in_array( 'IGNORE', $options ) ) {
1463                         $opts[] = 'IGNORE';
1464                 }
1465
1466                 return $opts;
1467         }
1468
1469         /**
1470          * Make UPDATE options for the DatabaseBase::update function
1471          *
1472          * @param array $options The options passed to DatabaseBase::update
1473          * @return string
1474          */
1475         protected function makeUpdateOptions( $options ) {
1476                 $opts = $this->makeUpdateOptionsArray( $options );
1477
1478                 return implode( ' ', $opts );
1479         }
1480
1481         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
1482                 $table = $this->tableName( $table );
1483                 $opts = $this->makeUpdateOptions( $options );
1484                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1485
1486                 if ( $conds !== array() && $conds !== '*' ) {
1487                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1488                 }
1489
1490                 return $this->query( $sql, $fname );
1491         }
1492
1493         public function makeList( $a, $mode = LIST_COMMA ) {
1494                 if ( !is_array( $a ) ) {
1495                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1496                 }
1497
1498                 $first = true;
1499                 $list = '';
1500
1501                 foreach ( $a as $field => $value ) {
1502                         if ( !$first ) {
1503                                 if ( $mode == LIST_AND ) {
1504                                         $list .= ' AND ';
1505                                 } elseif ( $mode == LIST_OR ) {
1506                                         $list .= ' OR ';
1507                                 } else {
1508                                         $list .= ',';
1509                                 }
1510                         } else {
1511                                 $first = false;
1512                         }
1513
1514                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1515                                 $list .= "($value)";
1516                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1517                                 $list .= "$value";
1518                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1519                                 // Remove null from array to be handled separately if found
1520                                 $includeNull = false;
1521                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
1522                                         $includeNull = true;
1523                                         unset( $value[$nullKey] );
1524                                 }
1525                                 if ( count( $value ) == 0 && !$includeNull ) {
1526                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1527                                 } elseif ( count( $value ) == 0 ) {
1528                                         // only check if $field is null
1529                                         $list .= "$field IS NULL";
1530                                 } else {
1531                                         // IN clause contains at least one valid element
1532                                         if ( $includeNull ) {
1533                                                 // Group subconditions to ensure correct precedence
1534                                                 $list .= '(';
1535                                         }
1536                                         if ( count( $value ) == 1 ) {
1537                                                 // Special-case single values, as IN isn't terribly efficient
1538                                                 // Don't necessarily assume the single key is 0; we don't
1539                                                 // enforce linear numeric ordering on other arrays here.
1540                                                 $value = array_values( $value );
1541                                                 $list .= $field . " = " . $this->addQuotes( $value[0] );
1542                                         } else {
1543                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1544                                         }
1545                                         // if null present in array, append IS NULL
1546                                         if ( $includeNull ) {
1547                                                 $list .= " OR $field IS NULL)";
1548                                         }
1549                                 }
1550                         } elseif ( $value === null ) {
1551                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1552                                         $list .= "$field IS ";
1553                                 } elseif ( $mode == LIST_SET ) {
1554                                         $list .= "$field = ";
1555                                 }
1556                                 $list .= 'NULL';
1557                         } else {
1558                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1559                                         $list .= "$field = ";
1560                                 }
1561                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1562                         }
1563                 }
1564
1565                 return $list;
1566         }
1567
1568         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1569                 $conds = array();
1570
1571                 foreach ( $data as $base => $sub ) {
1572                         if ( count( $sub ) ) {
1573                                 $conds[] = $this->makeList(
1574                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1575                                         LIST_AND );
1576                         }
1577                 }
1578
1579                 if ( $conds ) {
1580                         return $this->makeList( $conds, LIST_OR );
1581                 } else {
1582                         // Nothing to search for...
1583                         return false;
1584                 }
1585         }
1586
1587         /**
1588          * Return aggregated value alias
1589          *
1590          * @param array $valuedata
1591          * @param string $valuename
1592          *
1593          * @return string
1594          */
1595         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1596                 return $valuename;
1597         }
1598
1599         public function bitNot( $field ) {
1600                 return "(~$field)";
1601         }
1602
1603         public function bitAnd( $fieldLeft, $fieldRight ) {
1604                 return "($fieldLeft & $fieldRight)";
1605         }
1606
1607         public function bitOr( $fieldLeft, $fieldRight ) {
1608                 return "($fieldLeft | $fieldRight)";
1609         }
1610
1611         public function buildConcat( $stringList ) {
1612                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1613         }
1614
1615         public function buildGroupConcatField(
1616                 $delim, $table, $field, $conds = '', $join_conds = array()
1617         ) {
1618                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
1619
1620                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, array(), $join_conds ) . ')';
1621         }
1622
1623         public function selectDB( $db ) {
1624                 # Stub. Shouldn't cause serious problems if it's not overridden, but
1625                 # if your database engine supports a concept similar to MySQL's
1626                 # databases you may as well.
1627                 $this->mDBname = $db;
1628
1629                 return true;
1630         }
1631
1632         public function getDBname() {
1633                 return $this->mDBname;
1634         }
1635
1636         public function getServer() {
1637                 return $this->mServer;
1638         }
1639
1640         /**
1641          * Format a table name ready for use in constructing an SQL query
1642          *
1643          * This does two important things: it quotes the table names to clean them up,
1644          * and it adds a table prefix if only given a table name with no quotes.
1645          *
1646          * All functions of this object which require a table name call this function
1647          * themselves. Pass the canonical name to such functions. This is only needed
1648          * when calling query() directly.
1649          *
1650          * @param string $name Database table name
1651          * @param string $format One of:
1652          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1653          *            so that it can be used in a query.
1654          *   raw - Do not add identifier quotes to the table name
1655          * @return string Full database name
1656          */
1657         public function tableName( $name, $format = 'quoted' ) {
1658                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
1659                 # Skip the entire process when we have a string quoted on both ends.
1660                 # Note that we check the end so that we will still quote any use of
1661                 # use of `database`.table. But won't break things if someone wants
1662                 # to query a database table with a dot in the name.
1663                 if ( $this->isQuotedIdentifier( $name ) ) {
1664                         return $name;
1665                 }
1666
1667                 # Lets test for any bits of text that should never show up in a table
1668                 # name. Basically anything like JOIN or ON which are actually part of
1669                 # SQL queries, but may end up inside of the table value to combine
1670                 # sql. Such as how the API is doing.
1671                 # Note that we use a whitespace test rather than a \b test to avoid
1672                 # any remote case where a word like on may be inside of a table name
1673                 # surrounded by symbols which may be considered word breaks.
1674                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1675                         return $name;
1676                 }
1677
1678                 # Split database and table into proper variables.
1679                 # We reverse the explode so that database.table and table both output
1680                 # the correct table.
1681                 $dbDetails = explode( '.', $name, 3 );
1682                 if ( count( $dbDetails ) == 3 ) {
1683                         list( $database, $schema, $table ) = $dbDetails;
1684                         # We don't want any prefix added in this case
1685                         $prefix = '';
1686                 } elseif ( count( $dbDetails ) == 2 ) {
1687                         list( $database, $table ) = $dbDetails;
1688                         # We don't want any prefix added in this case
1689                         # In dbs that support it, $database may actually be the schema
1690                         # but that doesn't affect any of the functionality here
1691                         $prefix = '';
1692                         $schema = null;
1693                 } else {
1694                         list( $table ) = $dbDetails;
1695                         if ( $wgSharedDB !== null # We have a shared database
1696                                 && $this->mForeign == false # We're not working on a foreign database
1697                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
1698                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
1699                         ) {
1700                                 $database = $wgSharedDB;
1701                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
1702                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
1703                         } else {
1704                                 $database = null;
1705                                 $schema = $this->mSchema; # Default schema
1706                                 $prefix = $this->mTablePrefix; # Default prefix
1707                         }
1708                 }
1709
1710                 # Quote $table and apply the prefix if not quoted.
1711                 # $tableName might be empty if this is called from Database::replaceVars()
1712                 $tableName = "{$prefix}{$table}";
1713                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
1714                         $tableName = $this->addIdentifierQuotes( $tableName );
1715                 }
1716
1717                 # Quote $schema and merge it with the table name if needed
1718                 if ( strlen( $schema ) ) {
1719                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
1720                                 $schema = $this->addIdentifierQuotes( $schema );
1721                         }
1722                         $tableName = $schema . '.' . $tableName;
1723                 }
1724
1725                 # Quote $database and merge it with the table name if needed
1726                 if ( $database !== null ) {
1727                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
1728                                 $database = $this->addIdentifierQuotes( $database );
1729                         }
1730                         $tableName = $database . '.' . $tableName;
1731                 }
1732
1733                 return $tableName;
1734         }
1735
1736         /**
1737          * Fetch a number of table names into an array
1738          * This is handy when you need to construct SQL for joins
1739          *
1740          * Example:
1741          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
1742          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1743          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1744          *
1745          * @return array
1746          */
1747         public function tableNames() {
1748                 $inArray = func_get_args();
1749                 $retVal = array();
1750
1751                 foreach ( $inArray as $name ) {
1752                         $retVal[$name] = $this->tableName( $name );
1753                 }
1754
1755                 return $retVal;
1756         }
1757
1758         /**
1759          * Fetch a number of table names into an zero-indexed numerical array
1760          * This is handy when you need to construct SQL for joins
1761          *
1762          * Example:
1763          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
1764          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1765          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1766          *
1767          * @return array
1768          */
1769         public function tableNamesN() {
1770                 $inArray = func_get_args();
1771                 $retVal = array();
1772
1773                 foreach ( $inArray as $name ) {
1774                         $retVal[] = $this->tableName( $name );
1775                 }
1776
1777                 return $retVal;
1778         }
1779
1780         /**
1781          * Get an aliased table name
1782          * e.g. tableName AS newTableName
1783          *
1784          * @param string $name Table name, see tableName()
1785          * @param string|bool $alias Alias (optional)
1786          * @return string SQL name for aliased table. Will not alias a table to its own name
1787          */
1788         public function tableNameWithAlias( $name, $alias = false ) {
1789                 if ( !$alias || $alias == $name ) {
1790                         return $this->tableName( $name );
1791                 } else {
1792                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
1793                 }
1794         }
1795
1796         /**
1797          * Gets an array of aliased table names
1798          *
1799          * @param array $tables Array( [alias] => table )
1800          * @return string[] See tableNameWithAlias()
1801          */
1802         public function tableNamesWithAlias( $tables ) {
1803                 $retval = array();
1804                 foreach ( $tables as $alias => $table ) {
1805                         if ( is_numeric( $alias ) ) {
1806                                 $alias = $table;
1807                         }
1808                         $retval[] = $this->tableNameWithAlias( $table, $alias );
1809                 }
1810
1811                 return $retval;
1812         }
1813
1814         /**
1815          * Get an aliased field name
1816          * e.g. fieldName AS newFieldName
1817          *
1818          * @param string $name Field name
1819          * @param string|bool $alias Alias (optional)
1820          * @return string SQL name for aliased field. Will not alias a field to its own name
1821          */
1822         public function fieldNameWithAlias( $name, $alias = false ) {
1823                 if ( !$alias || (string)$alias === (string)$name ) {
1824                         return $name;
1825                 } else {
1826                         return $name . ' AS ' . $alias; // PostgreSQL needs AS
1827                 }
1828         }
1829
1830         /**
1831          * Gets an array of aliased field names
1832          *
1833          * @param array $fields Array( [alias] => field )
1834          * @return string[] See fieldNameWithAlias()
1835          */
1836         public function fieldNamesWithAlias( $fields ) {
1837                 $retval = array();
1838                 foreach ( $fields as $alias => $field ) {
1839                         if ( is_numeric( $alias ) ) {
1840                                 $alias = $field;
1841                         }
1842                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
1843                 }
1844
1845                 return $retval;
1846         }
1847
1848         /**
1849          * Get the aliased table name clause for a FROM clause
1850          * which might have a JOIN and/or USE INDEX clause
1851          *
1852          * @param array $tables ( [alias] => table )
1853          * @param array $use_index Same as for select()
1854          * @param array $join_conds Same as for select()
1855          * @return string
1856          */
1857         protected function tableNamesWithUseIndexOrJOIN(
1858                 $tables, $use_index = array(), $join_conds = array()
1859         ) {
1860                 $ret = array();
1861                 $retJOIN = array();
1862                 $use_index = (array)$use_index;
1863                 $join_conds = (array)$join_conds;
1864
1865                 foreach ( $tables as $alias => $table ) {
1866                         if ( !is_string( $alias ) ) {
1867                                 // No alias? Set it equal to the table name
1868                                 $alias = $table;
1869                         }
1870                         // Is there a JOIN clause for this table?
1871                         if ( isset( $join_conds[$alias] ) ) {
1872                                 list( $joinType, $conds ) = $join_conds[$alias];
1873                                 $tableClause = $joinType;
1874                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
1875                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
1876                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
1877                                         if ( $use != '' ) {
1878                                                 $tableClause .= ' ' . $use;
1879                                         }
1880                                 }
1881                                 $on = $this->makeList( (array)$conds, LIST_AND );
1882                                 if ( $on != '' ) {
1883                                         $tableClause .= ' ON (' . $on . ')';
1884                                 }
1885
1886                                 $retJOIN[] = $tableClause;
1887                         } elseif ( isset( $use_index[$alias] ) ) {
1888                                 // Is there an INDEX clause for this table?
1889                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1890                                 $tableClause .= ' ' . $this->useIndexClause(
1891                                         implode( ',', (array)$use_index[$alias] )
1892                                 );
1893
1894                                 $ret[] = $tableClause;
1895                         } else {
1896                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
1897
1898                                 $ret[] = $tableClause;
1899                         }
1900                 }
1901
1902                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
1903                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
1904                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
1905
1906                 // Compile our final table clause
1907                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
1908         }
1909
1910         /**
1911          * Get the name of an index in a given table.
1912          *
1913          * @protected Don't use outside of DatabaseBase and childs
1914          * @param string $index
1915          * @return string
1916          */
1917         public function indexName( $index ) {
1918                 // @FIXME: Make this protected once we move away from PHP 5.3
1919                 // Needs to be public because of usage in closure (in DatabaseBase::replaceVars)
1920
1921                 // Backwards-compatibility hack
1922                 $renamed = array(
1923                         'ar_usertext_timestamp' => 'usertext_timestamp',
1924                         'un_user_id' => 'user_id',
1925                         'un_user_ip' => 'user_ip',
1926                 );
1927
1928                 if ( isset( $renamed[$index] ) ) {
1929                         return $renamed[$index];
1930                 } else {
1931                         return $index;
1932                 }
1933         }
1934
1935         public function addQuotes( $s ) {
1936                 if ( $s instanceof Blob ) {
1937                         $s = $s->fetch();
1938                 }
1939                 if ( $s === null ) {
1940                         return 'NULL';
1941                 } else {
1942                         # This will also quote numeric values. This should be harmless,
1943                         # and protects against weird problems that occur when they really
1944                         # _are_ strings such as article titles and string->number->string
1945                         # conversion is not 1:1.
1946                         return "'" . $this->strencode( $s ) . "'";
1947                 }
1948         }
1949
1950         /**
1951          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
1952          * MySQL uses `backticks` while basically everything else uses double quotes.
1953          * Since MySQL is the odd one out here the double quotes are our generic
1954          * and we implement backticks in DatabaseMysql.
1955          *
1956          * @param string $s
1957          * @return string
1958          */
1959         public function addIdentifierQuotes( $s ) {
1960                 return '"' . str_replace( '"', '""', $s ) . '"';
1961         }
1962
1963         /**
1964          * Returns if the given identifier looks quoted or not according to
1965          * the database convention for quoting identifiers .
1966          *
1967          * @param string $name
1968          * @return bool
1969          */
1970         public function isQuotedIdentifier( $name ) {
1971                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
1972         }
1973
1974         /**
1975          * @param string $s
1976          * @return string
1977          */
1978         protected function escapeLikeInternal( $s ) {
1979                 return addcslashes( $s, '\%_' );
1980         }
1981
1982         public function buildLike() {
1983                 $params = func_get_args();
1984
1985                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1986                         $params = $params[0];
1987                 }
1988
1989                 $s = '';
1990
1991                 foreach ( $params as $value ) {
1992                         if ( $value instanceof LikeMatch ) {
1993                                 $s .= $value->toString();
1994                         } else {
1995                                 $s .= $this->escapeLikeInternal( $value );
1996                         }
1997                 }
1998
1999                 return " LIKE {$this->addQuotes( $s )} ";
2000         }
2001
2002         public function anyChar() {
2003                 return new LikeMatch( '_' );
2004         }
2005
2006         public function anyString() {
2007                 return new LikeMatch( '%' );
2008         }
2009
2010         public function nextSequenceValue( $seqName ) {
2011                 return null;
2012         }
2013
2014         /**
2015          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2016          * is only needed because a) MySQL must be as efficient as possible due to
2017          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2018          * which index to pick. Anyway, other databases might have different
2019          * indexes on a given table. So don't bother overriding this unless you're
2020          * MySQL.
2021          * @param string $index
2022          * @return string
2023          */
2024         public function useIndexClause( $index ) {
2025                 return '';
2026         }
2027
2028         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2029                 $quotedTable = $this->tableName( $table );
2030
2031                 if ( count( $rows ) == 0 ) {
2032                         return;
2033                 }
2034
2035                 # Single row case
2036                 if ( !is_array( reset( $rows ) ) ) {
2037                         $rows = array( $rows );
2038                 }
2039
2040                 // @FXIME: this is not atomic, but a trx would break affectedRows()
2041                 foreach ( $rows as $row ) {
2042                         # Delete rows which collide
2043                         if ( $uniqueIndexes ) {
2044                                 $sql = "DELETE FROM $quotedTable WHERE ";
2045                                 $first = true;
2046                                 foreach ( $uniqueIndexes as $index ) {
2047                                         if ( $first ) {
2048                                                 $first = false;
2049                                                 $sql .= '( ';
2050                                         } else {
2051                                                 $sql .= ' ) OR ( ';
2052                                         }
2053                                         if ( is_array( $index ) ) {
2054                                                 $first2 = true;
2055                                                 foreach ( $index as $col ) {
2056                                                         if ( $first2 ) {
2057                                                                 $first2 = false;
2058                                                         } else {
2059                                                                 $sql .= ' AND ';
2060                                                         }
2061                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2062                                                 }
2063                                         } else {
2064                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2065                                         }
2066                                 }
2067                                 $sql .= ' )';
2068                                 $this->query( $sql, $fname );
2069                         }
2070
2071                         # Now insert the row
2072                         $this->insert( $table, $row, $fname );
2073                 }
2074         }
2075
2076         /**
2077          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2078          * statement.
2079          *
2080          * @param string $table Table name
2081          * @param array|string $rows Row(s) to insert
2082          * @param string $fname Caller function name
2083          *
2084          * @return ResultWrapper
2085          */
2086         protected function nativeReplace( $table, $rows, $fname ) {
2087                 $table = $this->tableName( $table );
2088
2089                 # Single row case
2090                 if ( !is_array( reset( $rows ) ) ) {
2091                         $rows = array( $rows );
2092                 }
2093
2094                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2095                 $first = true;
2096
2097                 foreach ( $rows as $row ) {
2098                         if ( $first ) {
2099                                 $first = false;
2100                         } else {
2101                                 $sql .= ',';
2102                         }
2103
2104                         $sql .= '(' . $this->makeList( $row ) . ')';
2105                 }
2106
2107                 return $this->query( $sql, $fname );
2108         }
2109
2110         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2111                 $fname = __METHOD__
2112         ) {
2113                 if ( !count( $rows ) ) {
2114                         return true; // nothing to do
2115                 }
2116
2117                 if ( !is_array( reset( $rows ) ) ) {
2118                         $rows = array( $rows );
2119                 }
2120
2121                 if ( count( $uniqueIndexes ) ) {
2122                         $clauses = array(); // list WHERE clauses that each identify a single row
2123                         foreach ( $rows as $row ) {
2124                                 foreach ( $uniqueIndexes as $index ) {
2125                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2126                                         $rowKey = array(); // unique key to this row
2127                                         foreach ( $index as $column ) {
2128                                                 $rowKey[$column] = $row[$column];
2129                                         }
2130                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2131                                 }
2132                         }
2133                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2134                 } else {
2135                         $where = false;
2136                 }
2137
2138                 $useTrx = !$this->mTrxLevel;
2139                 if ( $useTrx ) {
2140                         $this->begin( $fname );
2141                 }
2142                 try {
2143                         # Update any existing conflicting row(s)
2144                         if ( $where !== false ) {
2145                                 $ok = $this->update( $table, $set, $where, $fname );
2146                         } else {
2147                                 $ok = true;
2148                         }
2149                         # Now insert any non-conflicting row(s)
2150                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2151                 } catch ( Exception $e ) {
2152                         if ( $useTrx ) {
2153                                 $this->rollback( $fname );
2154                         }
2155                         throw $e;
2156                 }
2157                 if ( $useTrx ) {
2158                         $this->commit( $fname );
2159                 }
2160
2161                 return $ok;
2162         }
2163
2164         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2165                 $fname = __METHOD__
2166         ) {
2167                 if ( !$conds ) {
2168                         throw new DBUnexpectedError( $this,
2169                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2170                 }
2171
2172                 $delTable = $this->tableName( $delTable );
2173                 $joinTable = $this->tableName( $joinTable );
2174                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2175                 if ( $conds != '*' ) {
2176                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2177                 }
2178                 $sql .= ')';
2179
2180                 $this->query( $sql, $fname );
2181         }
2182
2183         /**
2184          * Returns the size of a text field, or -1 for "unlimited"
2185          *
2186          * @param string $table
2187          * @param string $field
2188          * @return int
2189          */
2190         public function textFieldSize( $table, $field ) {
2191                 $table = $this->tableName( $table );
2192                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2193                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2194                 $row = $this->fetchObject( $res );
2195
2196                 $m = array();
2197
2198                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2199                         $size = $m[1];
2200                 } else {
2201                         $size = -1;
2202                 }
2203
2204                 return $size;
2205         }
2206
2207         /**
2208          * A string to insert into queries to show that they're low-priority, like
2209          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
2210          * string and nothing bad should happen.
2211          *
2212          * @return string Returns the text of the low priority option if it is
2213          *   supported, or a blank string otherwise
2214          */
2215         public function lowPriorityOption() {
2216                 return '';
2217         }
2218
2219         public function delete( $table, $conds, $fname = __METHOD__ ) {
2220                 if ( !$conds ) {
2221                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2222                 }
2223
2224                 $table = $this->tableName( $table );
2225                 $sql = "DELETE FROM $table";
2226
2227                 if ( $conds != '*' ) {
2228                         if ( is_array( $conds ) ) {
2229                                 $conds = $this->makeList( $conds, LIST_AND );
2230                         }
2231                         $sql .= ' WHERE ' . $conds;
2232                 }
2233
2234                 return $this->query( $sql, $fname );
2235         }
2236
2237         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2238                 $fname = __METHOD__,
2239                 $insertOptions = array(), $selectOptions = array()
2240         ) {
2241                 $destTable = $this->tableName( $destTable );
2242
2243                 if ( !is_array( $insertOptions ) ) {
2244                         $insertOptions = array( $insertOptions );
2245                 }
2246
2247                 $insertOptions = $this->makeInsertOptions( $insertOptions );
2248
2249                 if ( !is_array( $selectOptions ) ) {
2250                         $selectOptions = array( $selectOptions );
2251                 }
2252
2253                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2254
2255                 if ( is_array( $srcTable ) ) {
2256                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2257                 } else {
2258                         $srcTable = $this->tableName( $srcTable );
2259                 }
2260
2261                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2262                         " SELECT $startOpts " . implode( ',', $varMap ) .
2263                         " FROM $srcTable $useIndex ";
2264
2265                 if ( $conds != '*' ) {
2266                         if ( is_array( $conds ) ) {
2267                                 $conds = $this->makeList( $conds, LIST_AND );
2268                         }
2269                         $sql .= " WHERE $conds";
2270                 }
2271
2272                 $sql .= " $tailOpts";
2273
2274                 return $this->query( $sql, $fname );
2275         }
2276
2277         /**
2278          * Construct a LIMIT query with optional offset. This is used for query
2279          * pages. The SQL should be adjusted so that only the first $limit rows
2280          * are returned. If $offset is provided as well, then the first $offset
2281          * rows should be discarded, and the next $limit rows should be returned.
2282          * If the result of the query is not ordered, then the rows to be returned
2283          * are theoretically arbitrary.
2284          *
2285          * $sql is expected to be a SELECT, if that makes a difference.
2286          *
2287          * The version provided by default works in MySQL and SQLite. It will very
2288          * likely need to be overridden for most other DBMSes.
2289          *
2290          * @param string $sql SQL query we will append the limit too
2291          * @param int $limit The SQL limit
2292          * @param int|bool $offset The SQL offset (default false)
2293          * @throws DBUnexpectedError
2294          * @return string
2295          */
2296         public function limitResult( $sql, $limit, $offset = false ) {
2297                 if ( !is_numeric( $limit ) ) {
2298                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2299                 }
2300
2301                 return "$sql LIMIT "
2302                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2303                         . "{$limit} ";
2304         }
2305
2306         public function unionSupportsOrderAndLimit() {
2307                 return true; // True for almost every DB supported
2308         }
2309
2310         public function unionQueries( $sqls, $all ) {
2311                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2312
2313                 return '(' . implode( $glue, $sqls ) . ')';
2314         }
2315
2316         public function conditional( $cond, $trueVal, $falseVal ) {
2317                 if ( is_array( $cond ) ) {
2318                         $cond = $this->makeList( $cond, LIST_AND );
2319                 }
2320
2321                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2322         }
2323
2324         public function strreplace( $orig, $old, $new ) {
2325                 return "REPLACE({$orig}, {$old}, {$new})";
2326         }
2327
2328         public function getServerUptime() {
2329                 return 0;
2330         }
2331
2332         public function wasDeadlock() {
2333                 return false;
2334         }
2335
2336         public function wasLockTimeout() {
2337                 return false;
2338         }
2339
2340         public function wasErrorReissuable() {
2341                 return false;
2342         }
2343
2344         public function wasReadOnlyError() {
2345                 return false;
2346         }
2347
2348         /**
2349          * Determines if the given query error was a connection drop
2350          * STUB
2351          *
2352          * @param integer|string $errno
2353          * @return bool
2354          */
2355         public function wasConnectionError( $errno ) {
2356                 return false;
2357         }
2358
2359         /**
2360          * Perform a deadlock-prone transaction.
2361          *
2362          * This function invokes a callback function to perform a set of write
2363          * queries. If a deadlock occurs during the processing, the transaction
2364          * will be rolled back and the callback function will be called again.
2365          *
2366          * Usage:
2367          *   $dbw->deadlockLoop( callback, ... );
2368          *
2369          * Extra arguments are passed through to the specified callback function.
2370          *
2371          * Returns whatever the callback function returned on its successful,
2372          * iteration, or false on error, for example if the retry limit was
2373          * reached.
2374          * @return mixed
2375          * @throws DBUnexpectedError
2376          * @throws Exception
2377          */
2378         public function deadlockLoop() {
2379                 $args = func_get_args();
2380                 $function = array_shift( $args );
2381                 $tries = self::DEADLOCK_TRIES;
2382
2383                 $this->begin( __METHOD__ );
2384
2385                 $retVal = null;
2386                 /** @var Exception $e */
2387                 $e = null;
2388                 do {
2389                         try {
2390                                 $retVal = call_user_func_array( $function, $args );
2391                                 break;
2392                         } catch ( DBQueryError $e ) {
2393                                 if ( $this->wasDeadlock() ) {
2394                                         // Retry after a randomized delay
2395                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2396                                 } else {
2397                                         // Throw the error back up
2398                                         throw $e;
2399                                 }
2400                         }
2401                 } while ( --$tries > 0 );
2402
2403                 if ( $tries <= 0 ) {
2404                         // Too many deadlocks; give up
2405                         $this->rollback( __METHOD__ );
2406                         throw $e;
2407                 } else {
2408                         $this->commit( __METHOD__ );
2409
2410                         return $retVal;
2411                 }
2412         }
2413
2414         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2415                 # Real waits are implemented in the subclass.
2416                 return 0;
2417         }
2418
2419         public function getSlavePos() {
2420                 # Stub
2421                 return false;
2422         }
2423
2424         public function getMasterPos() {
2425                 # Stub
2426                 return false;
2427         }
2428
2429         final public function onTransactionIdle( $callback ) {
2430                 $this->mTrxIdleCallbacks[] = array( $callback, wfGetCaller() );
2431                 if ( !$this->mTrxLevel ) {
2432                         $this->runOnTransactionIdleCallbacks();
2433                 }
2434         }
2435
2436         final public function onTransactionPreCommitOrIdle( $callback ) {
2437                 if ( $this->mTrxLevel ) {
2438                         $this->mTrxPreCommitCallbacks[] = array( $callback, wfGetCaller() );
2439                 } else {
2440                         $this->onTransactionIdle( $callback ); // this will trigger immediately
2441                 }
2442         }
2443
2444         /**
2445          * Actually any "on transaction idle" callbacks.
2446          *
2447          * @since 1.20
2448          */
2449         protected function runOnTransactionIdleCallbacks() {
2450                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
2451
2452                 $e = $ePrior = null; // last exception
2453                 do { // callbacks may add callbacks :)
2454                         $callbacks = $this->mTrxIdleCallbacks;
2455                         $this->mTrxIdleCallbacks = array(); // recursion guard
2456                         foreach ( $callbacks as $callback ) {
2457                                 try {
2458                                         list( $phpCallback ) = $callback;
2459                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
2460                                         call_user_func( $phpCallback );
2461                                         if ( $autoTrx ) {
2462                                                 $this->setFlag( DBO_TRX ); // restore automatic begin()
2463                                         } else {
2464                                                 $this->clearFlag( DBO_TRX ); // restore auto-commit
2465                                         }
2466                                 } catch ( Exception $e ) {
2467                                         if ( $ePrior ) {
2468                                                 MWExceptionHandler::logException( $ePrior );
2469                                         }
2470                                         $ePrior = $e;
2471                                         // Some callbacks may use startAtomic/endAtomic, so make sure
2472                                         // their transactions are ended so other callbacks don't fail
2473                                         if ( $this->trxLevel() ) {
2474                                                 $this->rollback( __METHOD__ );
2475                                         }
2476                                 }
2477                         }
2478                 } while ( count( $this->mTrxIdleCallbacks ) );
2479
2480                 if ( $e instanceof Exception ) {
2481                         throw $e; // re-throw any last exception
2482                 }
2483         }
2484
2485         /**
2486          * Actually any "on transaction pre-commit" callbacks.
2487          *
2488          * @since 1.22
2489          */
2490         protected function runOnTransactionPreCommitCallbacks() {
2491                 $e = $ePrior = null; // last exception
2492                 do { // callbacks may add callbacks :)
2493                         $callbacks = $this->mTrxPreCommitCallbacks;
2494                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
2495                         foreach ( $callbacks as $callback ) {
2496                                 try {
2497                                         list( $phpCallback ) = $callback;
2498                                         call_user_func( $phpCallback );
2499                                 } catch ( Exception $e ) {
2500                                         if ( $ePrior ) {
2501                                                 MWExceptionHandler::logException( $ePrior );
2502                                         }
2503                                         $ePrior = $e;
2504                                 }
2505                         }
2506                 } while ( count( $this->mTrxPreCommitCallbacks ) );
2507
2508                 if ( $e instanceof Exception ) {
2509                         throw $e; // re-throw any last exception
2510                 }
2511         }
2512
2513         final public function startAtomic( $fname = __METHOD__ ) {
2514                 if ( !$this->mTrxLevel ) {
2515                         $this->begin( $fname );
2516                         $this->mTrxAutomatic = true;
2517                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
2518                         // in all changes being in one transaction to keep requests transactional.
2519                         if ( !$this->getFlag( DBO_TRX ) ) {
2520                                 $this->mTrxAutomaticAtomic = true;
2521                         }
2522                 }
2523
2524                 $this->mTrxAtomicLevels[] = $fname;
2525         }
2526
2527         final public function endAtomic( $fname = __METHOD__ ) {
2528                 if ( !$this->mTrxLevel ) {
2529                         throw new DBUnexpectedError( $this, 'No atomic transaction is open.' );
2530                 }
2531                 if ( !$this->mTrxAtomicLevels ||
2532                         array_pop( $this->mTrxAtomicLevels ) !== $fname
2533                 ) {
2534                         throw new DBUnexpectedError( $this, 'Invalid atomic section ended.' );
2535                 }
2536
2537                 if ( !$this->mTrxAtomicLevels && $this->mTrxAutomaticAtomic ) {
2538                         $this->commit( $fname, 'flush' );
2539                 }
2540         }
2541
2542         final public function doAtomicSection( $fname, $callback ) {
2543                 if ( !is_callable( $callback ) ) {
2544                         throw new UnexpectedValueException( "Invalid callback." );
2545                 };
2546
2547                 $this->startAtomic( $fname );
2548                 try {
2549                         call_user_func_array( $callback, array( $this, $fname ) );
2550                 } catch ( Exception $e ) {
2551                         $this->rollback( $fname );
2552                         throw $e;
2553                 }
2554                 $this->endAtomic( $fname );
2555         }
2556
2557         final public function begin( $fname = __METHOD__ ) {
2558                 if ( $this->mTrxLevel ) { // implicit commit
2559                         if ( $this->mTrxAtomicLevels ) {
2560                                 // If the current transaction was an automatic atomic one, then we definitely have
2561                                 // a problem. Same if there is any unclosed atomic level.
2562                                 $levels = implode( ', ', $this->mTrxAtomicLevels );
2563                                 throw new DBUnexpectedError(
2564                                         $this,
2565                                         "Got explicit BEGIN from $fname while atomic section(s) $levels are open."
2566                                 );
2567                         } elseif ( !$this->mTrxAutomatic ) {
2568                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
2569                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
2570                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
2571                                         " performing implicit commit!";
2572                                 wfWarn( $msg );
2573                                 wfLogDBError( $msg,
2574                                         $this->getLogContext( array(
2575                                                 'method' => __METHOD__,
2576                                                 'fname' => $fname,
2577                                         ) )
2578                                 );
2579                         } else {
2580                                 // if the transaction was automatic and has done write operations
2581                                 if ( $this->mTrxDoneWrites ) {
2582                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
2583                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
2584                                         );
2585                                 }
2586                         }
2587
2588                         $this->runOnTransactionPreCommitCallbacks();
2589                         $writeTime = $this->pendingWriteQueryDuration();
2590                         $this->doCommit( $fname );
2591                         if ( $this->mTrxDoneWrites ) {
2592                                 $this->mDoneWrites = microtime( true );
2593                                 $this->getTransactionProfiler()->transactionWritingOut(
2594                                         $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2595                         }
2596                         $this->runOnTransactionIdleCallbacks();
2597                 }
2598
2599                 # Avoid fatals if close() was called
2600                 $this->assertOpen();
2601
2602                 $this->doBegin( $fname );
2603                 $this->mTrxTimestamp = microtime( true );
2604                 $this->mTrxFname = $fname;
2605                 $this->mTrxDoneWrites = false;
2606                 $this->mTrxAutomatic = false;
2607                 $this->mTrxAutomaticAtomic = false;
2608                 $this->mTrxAtomicLevels = array();
2609                 $this->mTrxIdleCallbacks = array();
2610                 $this->mTrxPreCommitCallbacks = array();
2611                 $this->mTrxShortId = wfRandomString( 12 );
2612                 $this->mTrxWriteDuration = 0.0;
2613                 // First SELECT after BEGIN will establish the snapshot in REPEATABLE-READ.
2614                 // Get an estimate of the slave lag before then, treating estimate staleness
2615                 // as lag itself just to be safe
2616                 $status = $this->getApproximateLagStatus();
2617                 $this->mTrxSlaveLag = $status['lag'] + ( microtime( true ) - $status['since'] );
2618         }
2619
2620         /**
2621          * Issues the BEGIN command to the database server.
2622          *
2623          * @see DatabaseBase::begin()
2624          * @param string $fname
2625          */
2626         protected function doBegin( $fname ) {
2627                 $this->query( 'BEGIN', $fname );
2628                 $this->mTrxLevel = 1;
2629         }
2630
2631         final public function commit( $fname = __METHOD__, $flush = '' ) {
2632                 if ( $this->mTrxLevel && $this->mTrxAtomicLevels ) {
2633                         // There are still atomic sections open. This cannot be ignored
2634                         $levels = implode( ', ', $this->mTrxAtomicLevels );
2635                         throw new DBUnexpectedError(
2636                                 $this,
2637                                 "Got COMMIT while atomic sections $levels are still open"
2638                         );
2639                 }
2640
2641                 if ( $flush === 'flush' ) {
2642                         if ( !$this->mTrxLevel ) {
2643                                 return; // nothing to do
2644                         } elseif ( !$this->mTrxAutomatic ) {
2645                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
2646                         }
2647                 } else {
2648                         if ( !$this->mTrxLevel ) {
2649                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
2650                                 return; // nothing to do
2651                         } elseif ( $this->mTrxAutomatic ) {
2652                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
2653                         }
2654                 }
2655
2656                 # Avoid fatals if close() was called
2657                 $this->assertOpen();
2658
2659                 $this->runOnTransactionPreCommitCallbacks();
2660                 $writeTime = $this->pendingWriteQueryDuration();
2661                 $this->doCommit( $fname );
2662                 if ( $this->mTrxDoneWrites ) {
2663                         $this->mDoneWrites = microtime( true );
2664                         $this->getTransactionProfiler()->transactionWritingOut(
2665                                 $this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
2666                 }
2667                 $this->runOnTransactionIdleCallbacks();
2668         }
2669
2670         /**
2671          * Issues the COMMIT command to the database server.
2672          *
2673          * @see DatabaseBase::commit()
2674          * @param string $fname
2675          */
2676         protected function doCommit( $fname ) {
2677                 if ( $this->mTrxLevel ) {
2678                         $this->query( 'COMMIT', $fname );
2679                         $this->mTrxLevel = 0;
2680                 }
2681         }
2682
2683         final public function rollback( $fname = __METHOD__, $flush = '' ) {
2684                 if ( $flush !== 'flush' ) {
2685                         if ( !$this->mTrxLevel ) {
2686                                 wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
2687                                 return; // nothing to do
2688                         }
2689                 } else {
2690                         if ( !$this->mTrxLevel ) {
2691                                 return; // nothing to do
2692                         }
2693                 }
2694
2695                 # Avoid fatals if close() was called
2696                 $this->assertOpen();
2697
2698                 $this->doRollback( $fname );
2699                 $this->mTrxIdleCallbacks = array(); // cancel
2700                 $this->mTrxPreCommitCallbacks = array(); // cancel
2701                 $this->mTrxAtomicLevels = array();
2702                 if ( $this->mTrxDoneWrites ) {
2703                         $this->getTransactionProfiler()->transactionWritingOut(
2704                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
2705                 }
2706         }
2707
2708         /**
2709          * Issues the ROLLBACK command to the database server.
2710          *
2711          * @see DatabaseBase::rollback()
2712          * @param string $fname
2713          */
2714         protected function doRollback( $fname ) {
2715                 if ( $this->mTrxLevel ) {
2716                         $this->query( 'ROLLBACK', $fname, true );
2717                         $this->mTrxLevel = 0;
2718                 }
2719         }
2720
2721         /**
2722          * Creates a new table with structure copied from existing table
2723          * Note that unlike most database abstraction functions, this function does not
2724          * automatically append database prefix, because it works at a lower
2725          * abstraction level.
2726          * The table names passed to this function shall not be quoted (this
2727          * function calls addIdentifierQuotes when needed).
2728          *
2729          * @param string $oldName Name of table whose structure should be copied
2730          * @param string $newName Name of table to be created
2731          * @param bool $temporary Whether the new table should be temporary
2732          * @param string $fname Calling function name
2733          * @throws MWException
2734          * @return bool True if operation was successful
2735          */
2736         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
2737                 $fname = __METHOD__
2738         ) {
2739                 throw new MWException(
2740                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2741         }
2742
2743         function listTables( $prefix = null, $fname = __METHOD__ ) {
2744                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2745         }
2746
2747         /**
2748          * Reset the views process cache set by listViews()
2749          * @since 1.22
2750          */
2751         final public function clearViewsCache() {
2752                 $this->allViews = null;
2753         }
2754
2755         /**
2756          * Lists all the VIEWs in the database
2757          *
2758          * For caching purposes the list of all views should be stored in
2759          * $this->allViews. The process cache can be cleared with clearViewsCache()
2760          *
2761          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
2762          * @param string $fname Name of calling function
2763          * @throws MWException
2764          * @return array
2765          * @since 1.22
2766          */
2767         public function listViews( $prefix = null, $fname = __METHOD__ ) {
2768                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
2769         }
2770
2771         /**
2772          * Differentiates between a TABLE and a VIEW
2773          *
2774          * @param string $name Name of the database-structure to test.
2775          * @throws MWException
2776          * @return bool
2777          * @since 1.22
2778          */
2779         public function isView( $name ) {
2780                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
2781         }
2782
2783         public function timestamp( $ts = 0 ) {
2784                 return wfTimestamp( TS_MW, $ts );
2785         }
2786
2787         public function timestampOrNull( $ts = null ) {
2788                 if ( is_null( $ts ) ) {
2789                         return null;
2790                 } else {
2791                         return $this->timestamp( $ts );
2792                 }
2793         }
2794
2795         /**
2796          * Take the result from a query, and wrap it in a ResultWrapper if
2797          * necessary. Boolean values are passed through as is, to indicate success
2798          * of write queries or failure.
2799          *
2800          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2801          * resource, and it was necessary to call this function to convert it to
2802          * a wrapper. Nowadays, raw database objects are never exposed to external
2803          * callers, so this is unnecessary in external code.
2804          *
2805          * @param bool|ResultWrapper|resource|object $result
2806          * @return bool|ResultWrapper
2807          */
2808         protected function resultObject( $result ) {
2809                 if ( !$result ) {
2810                         return false;
2811                 } elseif ( $result instanceof ResultWrapper ) {
2812                         return $result;
2813                 } elseif ( $result === true ) {
2814                         // Successful write query
2815                         return $result;
2816                 } else {
2817                         return new ResultWrapper( $this, $result );
2818                 }
2819         }
2820
2821         public function ping() {
2822                 # Stub. Not essential to override.
2823                 return true;
2824         }
2825
2826         public function getSessionLagStatus() {
2827                 return $this->getTransactionLagStatus() ?: $this->getApproximateLagStatus();
2828         }
2829
2830         /**
2831          * Get the slave lag when the current transaction started
2832          *
2833          * This is useful when transactions might use snapshot isolation
2834          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
2835          * is this lag plus transaction duration. If they don't, it is still
2836          * safe to be pessimistic. This returns null if there is no transaction.
2837          *
2838          * @return array|null ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
2839          * @since 1.27
2840          */
2841         public function getTransactionLagStatus() {
2842                 return $this->mTrxLevel
2843                         ? array( 'lag' => $this->mTrxSlaveLag, 'since' => $this->trxTimestamp() )
2844                         : null;
2845         }
2846
2847         /**
2848          * Get a slave lag estimate for this server
2849          *
2850          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of estimate)
2851          * @since 1.27
2852          */
2853         public function getApproximateLagStatus() {
2854                 return array(
2855                         'lag'   => $this->getLBInfo( 'slave' ) ? $this->getLag() : 0,
2856                         'since' => microtime( true )
2857                 );
2858         }
2859
2860         /**
2861          * Merge the result of getSessionLagStatus() for several DBs
2862          * using the most pessimistic values to estimate the lag of
2863          * any data derived from them in combination
2864          *
2865          * This is information is useful for caching modules
2866          *
2867          * @see WANObjectCache::set()
2868          * @see WANObjectCache::getWithSetCallback()
2869          *
2870          * @param IDatabase $db1
2871          * @param IDatabase ...
2872          * @return array Map of values:
2873          *   - lag: highest lag of any of the DBs or false on error (e.g. replication stopped)
2874          *   - since: oldest UNIX timestamp of any of the DB lag estimates
2875          *   - pending: whether any of the DBs have uncommitted changes
2876          * @since 1.27
2877          */
2878         public static function getCacheSetOptions( IDatabase $db1 ) {
2879                 $res = array( 'lag' => 0, 'since' => INF, 'pending' => false );
2880                 foreach ( func_get_args() as $db ) {
2881                         /** @var IDatabase $db */
2882                         $status = $db->getSessionLagStatus();
2883                         if ( $status['lag'] === false ) {
2884                                 $res['lag'] = false;
2885                         } elseif ( $res['lag'] !== false ) {
2886                                 $res['lag'] = max( $res['lag'], $status['lag'] );
2887                         }
2888                         $res['since'] = min( $res['since'], $status['since'] );
2889                         $res['pending'] = $res['pending'] ?: $db->writesPending();
2890                 }
2891
2892                 return $res;
2893         }
2894
2895         public function getLag() {
2896                 return 0;
2897         }
2898
2899         function maxListLen() {
2900                 return 0;
2901         }
2902
2903         public function encodeBlob( $b ) {
2904                 return $b;
2905         }
2906
2907         public function decodeBlob( $b ) {
2908                 if ( $b instanceof Blob ) {
2909                         $b = $b->fetch();
2910                 }
2911                 return $b;
2912         }
2913
2914         public function setSessionOptions( array $options ) {
2915         }
2916
2917         /**
2918          * Read and execute SQL commands from a file.
2919          *
2920          * Returns true on success, error string or exception on failure (depending
2921          * on object's error ignore settings).
2922          *
2923          * @param string $filename File name to open
2924          * @param bool|callable $lineCallback Optional function called before reading each line
2925          * @param bool|callable $resultCallback Optional function called for each MySQL result
2926          * @param bool|string $fname Calling function name or false if name should be
2927          *   generated dynamically using $filename
2928          * @param bool|callable $inputCallback Optional function called for each
2929          *   complete line sent
2930          * @throws Exception|MWException
2931          * @return bool|string
2932          */
2933         public function sourceFile(
2934                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
2935         ) {
2936                 MediaWiki\suppressWarnings();
2937                 $fp = fopen( $filename, 'r' );
2938                 MediaWiki\restoreWarnings();
2939
2940                 if ( false === $fp ) {
2941                         throw new MWException( "Could not open \"{$filename}\".\n" );
2942                 }
2943
2944                 if ( !$fname ) {
2945                         $fname = __METHOD__ . "( $filename )";
2946                 }
2947
2948                 try {
2949                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
2950                 } catch ( Exception $e ) {
2951                         fclose( $fp );
2952                         throw $e;
2953                 }
2954
2955                 fclose( $fp );
2956
2957                 return $error;
2958         }
2959
2960         /**
2961          * Get the full path of a patch file. Originally based on archive()
2962          * from updaters.inc. Keep in mind this always returns a patch, as
2963          * it fails back to MySQL if no DB-specific patch can be found
2964          *
2965          * @param string $patch The name of the patch, like patch-something.sql
2966          * @return string Full path to patch file
2967          */
2968         public function patchPath( $patch ) {
2969                 global $IP;
2970
2971                 $dbType = $this->getType();
2972                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
2973                         return "$IP/maintenance/$dbType/archives/$patch";
2974                 } else {
2975                         return "$IP/maintenance/archives/$patch";
2976                 }
2977         }
2978
2979         public function setSchemaVars( $vars ) {
2980                 $this->mSchemaVars = $vars;
2981         }
2982
2983         /**
2984          * Read and execute commands from an open file handle.
2985          *
2986          * Returns true on success, error string or exception on failure (depending
2987          * on object's error ignore settings).
2988          *
2989          * @param resource $fp File handle
2990          * @param bool|callable $lineCallback Optional function called before reading each query
2991          * @param bool|callable $resultCallback Optional function called for each MySQL result
2992          * @param string $fname Calling function name
2993          * @param bool|callable $inputCallback Optional function called for each complete query sent
2994          * @return bool|string
2995          */
2996         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
2997                 $fname = __METHOD__, $inputCallback = false
2998         ) {
2999                 $cmd = '';
3000
3001                 while ( !feof( $fp ) ) {
3002                         if ( $lineCallback ) {
3003                                 call_user_func( $lineCallback );
3004                         }
3005
3006                         $line = trim( fgets( $fp ) );
3007
3008                         if ( $line == '' ) {
3009                                 continue;
3010                         }
3011
3012                         if ( '-' == $line[0] && '-' == $line[1] ) {
3013                                 continue;
3014                         }
3015
3016                         if ( $cmd != '' ) {
3017                                 $cmd .= ' ';
3018                         }
3019
3020                         $done = $this->streamStatementEnd( $cmd, $line );
3021
3022                         $cmd .= "$line\n";
3023
3024                         if ( $done || feof( $fp ) ) {
3025                                 $cmd = $this->replaceVars( $cmd );
3026
3027                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3028                                         $res = $this->query( $cmd, $fname );
3029
3030                                         if ( $resultCallback ) {
3031                                                 call_user_func( $resultCallback, $res, $this );
3032                                         }
3033
3034                                         if ( false === $res ) {
3035                                                 $err = $this->lastError();
3036
3037                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3038                                         }
3039                                 }
3040                                 $cmd = '';
3041                         }
3042                 }
3043
3044                 return true;
3045         }
3046
3047         /**
3048          * Called by sourceStream() to check if we've reached a statement end
3049          *
3050          * @param string $sql SQL assembled so far
3051          * @param string $newLine New line about to be added to $sql
3052          * @return bool Whether $newLine contains end of the statement
3053          */
3054         public function streamStatementEnd( &$sql, &$newLine ) {
3055                 if ( $this->delimiter ) {
3056                         $prev = $newLine;
3057                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3058                         if ( $newLine != $prev ) {
3059                                 return true;
3060                         }
3061                 }
3062
3063                 return false;
3064         }
3065
3066         /**
3067          * Database independent variable replacement. Replaces a set of variables
3068          * in an SQL statement with their contents as given by $this->getSchemaVars().
3069          *
3070          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3071          *
3072          * - '{$var}' should be used for text and is passed through the database's
3073          *   addQuotes method.
3074          * - `{$var}` should be used for identifiers (e.g. table and database names).
3075          *   It is passed through the database's addIdentifierQuotes method which
3076          *   can be overridden if the database uses something other than backticks.
3077          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
3078          *   database's tableName method.
3079          * - / *i* / passes the name that follows through the database's indexName method.
3080          * - In all other cases, / *$var* / is left unencoded. Except for table options,
3081          *   its use should be avoided. In 1.24 and older, string encoding was applied.
3082          *
3083          * @param string $ins SQL statement to replace variables in
3084          * @return string The new SQL statement with variables replaced
3085          */
3086         protected function replaceVars( $ins ) {
3087                 $that = $this;
3088                 $vars = $this->getSchemaVars();
3089                 return preg_replace_callback(
3090                         '!
3091                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
3092                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
3093                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
3094                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
3095                         !x',
3096                         function ( $m ) use ( $that, $vars ) {
3097                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
3098                                 // check for both nonexistent keys *and* the empty string.
3099                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
3100                                         if ( $m[1] === 'i' ) {
3101                                                 return $that->indexName( $m[2] );
3102                                         } else {
3103                                                 return $that->tableName( $m[2] );
3104                                         }
3105                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
3106                                         return $that->addQuotes( $vars[$m[3]] );
3107                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
3108                                         return $that->addIdentifierQuotes( $vars[$m[4]] );
3109                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
3110                                         return $vars[$m[5]];
3111                                 } else {
3112                                         return $m[0];
3113                                 }
3114                         },
3115                         $ins
3116                 );
3117         }
3118
3119         /**
3120          * Get schema variables. If none have been set via setSchemaVars(), then
3121          * use some defaults from the current object.
3122          *
3123          * @return array
3124          */
3125         protected function getSchemaVars() {
3126                 if ( $this->mSchemaVars ) {
3127                         return $this->mSchemaVars;
3128                 } else {
3129                         return $this->getDefaultSchemaVars();
3130                 }
3131         }
3132
3133         /**
3134          * Get schema variables to use if none have been set via setSchemaVars().
3135          *
3136          * Override this in derived classes to provide variables for tables.sql
3137          * and SQL patch files.
3138          *
3139          * @return array
3140          */
3141         protected function getDefaultSchemaVars() {
3142                 return array();
3143         }
3144
3145         public function lockIsFree( $lockName, $method ) {
3146                 return true;
3147         }
3148
3149         public function lock( $lockName, $method, $timeout = 5 ) {
3150                 return true;
3151         }
3152
3153         public function unlock( $lockName, $method ) {
3154                 return true;
3155         }
3156
3157         public function namedLocksEnqueue() {
3158                 return false;
3159         }
3160
3161         /**
3162          * Lock specific tables
3163          *
3164          * @param array $read Array of tables to lock for read access
3165          * @param array $write Array of tables to lock for write access
3166          * @param string $method Name of caller
3167          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3168          * @return bool
3169          */
3170         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3171                 return true;
3172         }
3173
3174         /**
3175          * Unlock specific tables
3176          *
3177          * @param string $method The caller
3178          * @return bool
3179          */
3180         public function unlockTables( $method ) {
3181                 return true;
3182         }
3183
3184         /**
3185          * Delete a table
3186          * @param string $tableName
3187          * @param string $fName
3188          * @return bool|ResultWrapper
3189          * @since 1.18
3190          */
3191         public function dropTable( $tableName, $fName = __METHOD__ ) {
3192                 if ( !$this->tableExists( $tableName, $fName ) ) {
3193                         return false;
3194                 }
3195                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3196                 if ( $this->cascadingDeletes() ) {
3197                         $sql .= " CASCADE";
3198                 }
3199
3200                 return $this->query( $sql, $fName );
3201         }
3202
3203         /**
3204          * Get search engine class. All subclasses of this need to implement this
3205          * if they wish to use searching.
3206          *
3207          * @return string
3208          */
3209         public function getSearchEngine() {
3210                 return 'SearchEngineDummy';
3211         }
3212
3213         public function getInfinity() {
3214                 return 'infinity';
3215         }
3216
3217         public function encodeExpiry( $expiry ) {
3218                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3219                         ? $this->getInfinity()
3220                         : $this->timestamp( $expiry );
3221         }
3222
3223         public function decodeExpiry( $expiry, $format = TS_MW ) {
3224                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3225                         ? 'infinity'
3226                         : wfTimestamp( $format, $expiry );
3227         }
3228
3229         public function setBigSelects( $value = true ) {
3230                 // no-op
3231         }
3232
3233         public function isReadOnly() {
3234                 return ( $this->getReadOnlyReason() !== false );
3235         }
3236
3237         /**
3238          * @return string|bool Reason this DB is read-only or false if it is not
3239          */
3240         protected function getReadOnlyReason() {
3241                 $reason = $this->getLBInfo( 'readOnlyReason' );
3242
3243                 return is_string( $reason ) ? $reason : false;
3244         }
3245
3246         /**
3247          * @since 1.19
3248          * @return string
3249          */
3250         public function __toString() {
3251                 return (string)$this->mConn;
3252         }
3253
3254         /**
3255          * Run a few simple sanity checks
3256          */
3257         public function __destruct() {
3258                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
3259                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
3260                 }
3261                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
3262                         $callers = array();
3263                         foreach ( $this->mTrxIdleCallbacks as $callbackInfo ) {
3264                                 $callers[] = $callbackInfo[1];
3265                         }
3266                         $callers = implode( ', ', $callers );
3267                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
3268                 }
3269         }
3270 }
3271
3272 /**
3273  * @since 1.27
3274  */
3275 abstract class Database extends DatabaseBase {
3276         // B/C until nothing type hints for DatabaseBase
3277         // @TODO: finish renaming DatabaseBase => Database
3278 }