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  * Interface for classes that implement or wrap DatabaseBase
  30  * @ingroup Database
  31  */
  32 interface IDatabase {
  33 }
  34
  35 /**
  36  * Database abstraction object
  37  * @ingroup Database
  38  */
  39 abstract class DatabaseBase implements IDatabase {
  40         /** Number of times to re-try an operation in case of deadlock */
  41         const DEADLOCK_TRIES = 4;
  42
  43         /** Minimum time to wait before retry, in microseconds */
  44         const DEADLOCK_DELAY_MIN = 500000;
  45
  46         /** Maximum time to wait before retry */
  47         const DEADLOCK_DELAY_MAX = 1500000;
  48
  49         protected $mLastQuery = '';
  50         protected $mDoneWrites = false;
  51         protected $mPHPError = false;
  52
  53         protected $mServer, $mUser, $mPassword, $mDBname;
  54
  55         /** @var resource Database connection */
  56         protected $mConn = null;
  57         protected $mOpened = false;
  58
  59         /** @var callable[] */
  60         protected $mTrxIdleCallbacks = array();
  61         /** @var callable[] */
  62         protected $mTrxPreCommitCallbacks = array();
  63
  64         protected $mTablePrefix;
  65         protected $mSchema;
  66         protected $mFlags;
  67         protected $mForeign;
  68         protected $mErrorCount = 0;
  69         protected $mLBInfo = array();
  70         protected $mDefaultBigSelects = null;
  71         protected $mSchemaVars = false;
  72
  73         protected $preparedArgs;
  74
  75         protected $htmlErrors;
  76
  77         protected $delimiter = ';';
  78
  79         /**
  80          * Either 1 if a transaction is active or 0 otherwise.
  81          * The other Trx fields may not be meaningfull if this is 0.
  82          *
  83          * @var int
  84          */
  85         protected $mTrxLevel = 0;
  86
  87         /**
  88          * Either a short hexidecimal string if a transaction is active or ""
  89          *
  90          * @var string
  91          * @see DatabaseBase::mTrxLevel
  92          */
  93         protected $mTrxShortId = '';
  94
  95         /**
  96          * The UNIX time that the transaction started. Callers can assume that if
  97          * snapshot isolation is used, then the data is *at least* up to date to that
  98          * point (possibly more up-to-date since the first SELECT defines the snapshot).
  99          *
 100          * @var float|null
 101          * @see DatabaseBase::mTrxLevel
 102          */
 103         private $mTrxTimestamp = 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 SplStack
 134          */
 135         private $mTrxAtomicLevels;
 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          * @since 1.21
 146          * @var resource File handle for upgrade
 147          */
 148         protected $fileHandle = null;
 149
 150         /**
 151          * @since 1.22
 152          * @var string[] Process cache of VIEWs names in the database
 153          */
 154         protected $allViews = null;
 155
 156         /**
 157          * A string describing the current software version, and possibly
 158          * other details in a user-friendly way. Will be listed on Special:Version, etc.
 159          * Use getServerVersion() to get machine-friendly information.
 160          *
 161          * @return string Version information from the database server
 162          */
 163         public function getServerInfo() {
 164                 return $this->getServerVersion();
 165         }
 166
 167         /**
 168          * @return string Command delimiter used by this database engine
 169          */
 170         public function getDelimiter() {
 171                 return $this->delimiter;
 172         }
 173
 174         /**
 175          * Boolean, controls output of large amounts of debug information.
 176          * @param bool|null $debug
 177          *   - true to enable debugging
 178          *   - false to disable debugging
 179          *   - omitted or null to do nothing
 180          *
 181          * @return bool|null Previous value of the flag
 182          */
 183         public function debug( $debug = null ) {
 184                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 185         }
 186
 187         /**
 188          * Turns buffering of SQL result sets on (true) or off (false). Default is
 189          * "on".
 190          *
 191          * Unbuffered queries are very troublesome in MySQL:
 192          *
 193          *   - If another query is executed while the first query is being read
 194          *     out, the first query is killed. This means you can't call normal
 195          *     MediaWiki functions while you are reading an unbuffered query result
 196          *     from a normal wfGetDB() connection.
 197          *
 198          *   - Unbuffered queries cause the MySQL server to use large amounts of
 199          *     memory and to hold broad locks which block other queries.
 200          *
 201          * If you want to limit client-side memory, it's almost always better to
 202          * split up queries into batches using a LIMIT clause than to switch off
 203          * buffering.
 204          *
 205          * @param null|bool $buffer
 206          * @return null|bool The previous value of the flag
 207          */
 208         public function bufferResults( $buffer = null ) {
 209                 if ( is_null( $buffer ) ) {
 210                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 211                 } else {
 212                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 213                 }
 214         }
 215
 216         /**
 217          * Turns on (false) or off (true) the automatic generation and sending
 218          * of a "we're sorry, but there has been a database error" page on
 219          * database errors. Default is on (false). When turned off, the
 220          * code should use lastErrno() and lastError() to handle the
 221          * situation as appropriate.
 222          *
 223          * Do not use this function outside of the Database classes.
 224          *
 225          * @param null|bool $ignoreErrors
 226          * @return bool The previous value of the flag.
 227          */
 228         public function ignoreErrors( $ignoreErrors = null ) {
 229                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 230         }
 231
 232         /**
 233          * Gets the current transaction level.
 234          *
 235          * Historically, transactions were allowed to be "nested". This is no
 236          * longer supported, so this function really only returns a boolean.
 237          *
 238          * @return int The previous value
 239          */
 240         public function trxLevel() {
 241                 return $this->mTrxLevel;
 242         }
 243
 244         /**
 245          * Get the UNIX timestamp of the time that the transaction was established
 246          *
 247          * This can be used to reason about the staleness of SELECT data
 248          * in REPEATABLE-READ transaction isolation level.
 249          *
 250          * @return float|null Returns null if there is not active transaction
 251          * @since 1.25
 252          */
 253         public function trxTimestamp() {
 254                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 255         }
 256
 257         /**
 258          * Get/set the number of errors logged. Only useful when errors are ignored
 259          * @param int $count The count to set, or omitted to leave it unchanged.
 260          * @return int The error count
 261          */
 262         public function errorCount( $count = null ) {
 263                 return wfSetVar( $this->mErrorCount, $count );
 264         }
 265
 266         /**
 267          * Get/set the table prefix.
 268          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 269          * @return string The previous table prefix.
 270          */
 271         public function tablePrefix( $prefix = null ) {
 272                 return wfSetVar( $this->mTablePrefix, $prefix );
 273         }
 274
 275         /**
 276          * Get/set the db schema.
 277          * @param string $schema The database schema to set, or omitted to leave it unchanged.
 278          * @return string The previous db schema.
 279          */
 280         public function dbSchema( $schema = null ) {
 281                 return wfSetVar( $this->mSchema, $schema );
 282         }
 283
 284         /**
 285          * Set the filehandle to copy write statements to.
 286          *
 287          * @param resource $fh File handle
 288          */
 289         public function setFileHandle( $fh ) {
 290                 $this->fileHandle = $fh;
 291         }
 292
 293         /**
 294          * Get properties passed down from the server info array of the load
 295          * balancer.
 296          *
 297          * @param string $name The entry of the info array to get, or null to get the
 298          *   whole array
 299          *
 300          * @return array|mixed|null
 301          */
 302         public function getLBInfo( $name = null ) {
 303                 if ( is_null( $name ) ) {
 304                         return $this->mLBInfo;
 305                 } else {
 306                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 307                                 return $this->mLBInfo[$name];
 308                         } else {
 309                                 return null;
 310                         }
 311                 }
 312         }
 313
 314         /**
 315          * Set the LB info array, or a member of it. If called with one parameter,
 316          * the LB info array is set to that parameter. If it is called with two
 317          * parameters, the member with the given name is set to the given value.
 318          *
 319          * @param string $name
 320          * @param array $value
 321          */
 322         public function setLBInfo( $name, $value = null ) {
 323                 if ( is_null( $value ) ) {
 324                         $this->mLBInfo = $name;
 325                 } else {
 326                         $this->mLBInfo[$name] = $value;
 327                 }
 328         }
 329
 330         /**
 331          * Set lag time in seconds for a fake slave
 332          *
 333          * @param mixed $lag Valid values for this parameter are determined by the
 334          *   subclass, but should be a PHP scalar or array that would be sensible
 335          *   as part of $wgLBFactoryConf.
 336          */
 337         public function setFakeSlaveLag( $lag ) {
 338         }
 339
 340         /**
 341          * Make this connection a fake master
 342          *
 343          * @param bool $enabled
 344          */
 345         public function setFakeMaster( $enabled = true ) {
 346         }
 347
 348         /**
 349          * Returns true if this database supports (and uses) cascading deletes
 350          *
 351          * @return bool
 352          */
 353         public function cascadingDeletes() {
 354                 return false;
 355         }
 356
 357         /**
 358          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 359          *
 360          * @return bool
 361          */
 362         public function cleanupTriggers() {
 363                 return false;
 364         }
 365
 366         /**
 367          * Returns true if this database is strict about what can be put into an IP field.
 368          * Specifically, it uses a NULL value instead of an empty string.
 369          *
 370          * @return bool
 371          */
 372         public function strictIPs() {
 373                 return false;
 374         }
 375
 376         /**
 377          * Returns true if this database uses timestamps rather than integers
 378          *
 379          * @return bool
 380          */
 381         public function realTimestamps() {
 382                 return false;
 383         }
 384
 385         /**
 386          * Returns true if this database does an implicit sort when doing GROUP BY
 387          *
 388          * @return bool
 389          */
 390         public function implicitGroupby() {
 391                 return true;
 392         }
 393
 394         /**
 395          * Returns true if this database does an implicit order by when the column has an index
 396          * For example: SELECT page_title FROM page LIMIT 1
 397          *
 398          * @return bool
 399          */
 400         public function implicitOrderby() {
 401                 return true;
 402         }
 403
 404         /**
 405          * Returns true if this database can do a native search on IP columns
 406          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 407          *
 408          * @return bool
 409          */
 410         public function searchableIPs() {
 411                 return false;
 412         }
 413
 414         /**
 415          * Returns true if this database can use functional indexes
 416          *
 417          * @return bool
 418          */
 419         public function functionalIndexes() {
 420                 return false;
 421         }
 422
 423         /**
 424          * Return the last query that went through DatabaseBase::query()
 425          * @return string
 426          */
 427         public function lastQuery() {
 428                 return $this->mLastQuery;
 429         }
 430
 431         /**
 432          * Returns true if the connection may have been used for write queries.
 433          * Should return true if unsure.
 434          *
 435          * @return bool
 436          */
 437         public function doneWrites() {
 438                 return (bool)$this->mDoneWrites;
 439         }
 440
 441         /**
 442          * Returns the last time the connection may have been used for write queries.
 443          * Should return a timestamp if unsure.
 444          *
 445          * @return int|float UNIX timestamp or false
 446          * @since 1.24
 447          */
 448         public function lastDoneWrites() {
 449                 return $this->mDoneWrites ?: false;
 450         }
 451
 452         /**
 453          * Returns true if there is a transaction open with possible write
 454          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 455          *
 456          * @return bool
 457          */
 458         public function writesOrCallbacksPending() {
 459                 return $this->mTrxLevel && (
 460                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 461                 );
 462         }
 463
 464         /**
 465          * Is a connection to the database open?
 466          * @return bool
 467          */
 468         public function isOpen() {
 469                 return $this->mOpened;
 470         }
 471
 472         /**
 473          * Set a flag for this connection
 474          *
 475          * @param int $flag DBO_* constants from Defines.php:
 476          *   - DBO_DEBUG: output some debug info (same as debug())
 477          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 478          *   - DBO_TRX: automatically start transactions
 479          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 480          *       and removes it in command line mode
 481          *   - DBO_PERSISTENT: use persistant database connection
 482          */
 483         public function setFlag( $flag ) {
 484                 global $wgDebugDBTransactions;
 485                 $this->mFlags |= $flag;
 486                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 487                         wfDebug( "Implicit transactions are now enabled.\n" );
 488                 }
 489         }
 490
 491         /**
 492          * Clear a flag for this connection
 493          *
 494          * @param int $flag DBO_* constants from Defines.php:
 495          *   - DBO_DEBUG: output some debug info (same as debug())
 496          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 497          *   - DBO_TRX: automatically start transactions
 498          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 499          *       and removes it in command line mode
 500          *   - DBO_PERSISTENT: use persistant database connection
 501          */
 502         public function clearFlag( $flag ) {
 503                 global $wgDebugDBTransactions;
 504                 $this->mFlags &= ~$flag;
 505                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 506                         wfDebug( "Implicit transactions are now disabled.\n" );
 507                 }
 508         }
 509
 510         /**
 511          * Returns a boolean whether the flag $flag is set for this connection
 512          *
 513          * @param int $flag DBO_* constants from Defines.php:
 514          *   - DBO_DEBUG: output some debug info (same as debug())
 515          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 516          *   - DBO_TRX: automatically start transactions
 517          *   - DBO_PERSISTENT: use persistant database connection
 518          * @return bool
 519          */
 520         public function getFlag( $flag ) {
 521                 return !!( $this->mFlags & $flag );
 522         }
 523
 524         /**
 525          * General read-only accessor
 526          *
 527          * @param string $name
 528          * @return string
 529          */
 530         public function getProperty( $name ) {
 531                 return $this->$name;
 532         }
 533
 534         /**
 535          * @return string
 536          */
 537         public function getWikiID() {
 538                 if ( $this->mTablePrefix ) {
 539                         return "{$this->mDBname}-{$this->mTablePrefix}";
 540                 } else {
 541                         return $this->mDBname;
 542                 }
 543         }
 544
 545         /**
 546          * Return a path to the DBMS-specific SQL file if it exists,
 547          * otherwise default SQL file
 548          *
 549          * @param string $filename
 550          * @return string
 551          */
 552         private function getSqlFilePath( $filename ) {
 553                 global $IP;
 554                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 555                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 556                         return $dbmsSpecificFilePath;
 557                 } else {
 558                         return "$IP/maintenance/$filename";
 559                 }
 560         }
 561
 562         /**
 563          * Return a path to the DBMS-specific schema file,
 564          * otherwise default to tables.sql
 565          *
 566          * @return string
 567          */
 568         public function getSchemaPath() {
 569                 return $this->getSqlFilePath( 'tables.sql' );
 570         }
 571
 572         /**
 573          * Return a path to the DBMS-specific update key file,
 574          * otherwise default to update-keys.sql
 575          *
 576          * @return string
 577          */
 578         public function getUpdateKeysPath() {
 579                 return $this->getSqlFilePath( 'update-keys.sql' );
 580         }
 581
 582         /**
 583          * Get the type of the DBMS, as it appears in $wgDBtype.
 584          *
 585          * @return string
 586          */
 587         abstract function getType();
 588
 589         /**
 590          * Open a connection to the database. Usually aborts on failure
 591          *
 592          * @param string $server Database server host
 593          * @param string $user Database user name
 594          * @param string $password Database user password
 595          * @param string $dbName Database name
 596          * @return bool
 597          * @throws DBConnectionError
 598          */
 599         abstract function open( $server, $user, $password, $dbName );
 600
 601         /**
 602          * Fetch the next row from the given result object, in object form.
 603          * Fields can be retrieved with $row->fieldname, with fields acting like
 604          * member variables.
 605          * If no more rows are available, false is returned.
 606          *
 607          * @param ResultWrapper|stdClass $res Object as returned from DatabaseBase::query(), etc.
 608          * @return stdClass|bool
 609          * @throws DBUnexpectedError Thrown if the database returns an error
 610          */
 611         abstract function fetchObject( $res );
 612
 613         /**
 614          * Fetch the next row from the given result object, in associative array
 615          * form. Fields are retrieved with $row['fieldname'].
 616          * If no more rows are available, false is returned.
 617          *
 618          * @param ResultWrapper $res Result object as returned from DatabaseBase::query(), etc.
 619          * @return array|bool
 620          * @throws DBUnexpectedError Thrown if the database returns an error
 621          */
 622         abstract function fetchRow( $res );
 623
 624         /**
 625          * Get the number of rows in a result object
 626          *
 627          * @param mixed $res A SQL result
 628          * @return int
 629          */
 630         abstract function numRows( $res );
 631
 632         /**
 633          * Get the number of fields in a result object
 634          * @see http://www.php.net/mysql_num_fields
 635          *
 636          * @param mixed $res A SQL result
 637          * @return int
 638          */
 639         abstract function numFields( $res );
 640
 641         /**
 642          * Get a field name in a result object
 643          * @see http://www.php.net/mysql_field_name
 644          *
 645          * @param mixed $res A SQL result
 646          * @param int $n
 647          * @return string
 648          */
 649         abstract function fieldName( $res, $n );
 650
 651         /**
 652          * Get the inserted value of an auto-increment row
 653          *
 654          * The value inserted should be fetched from nextSequenceValue()
 655          *
 656          * Example:
 657          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 658          * $dbw->insert( 'page', array( 'page_id' => $id ) );
 659          * $id = $dbw->insertId();
 660          *
 661          * @return int
 662          */
 663         abstract function insertId();
 664
 665         /**
 666          * Change the position of the cursor in a result object
 667          * @see http://www.php.net/mysql_data_seek
 668          *
 669          * @param mixed $res A SQL result
 670          * @param int $row
 671          */
 672         abstract function dataSeek( $res, $row );
 673
 674         /**
 675          * Get the last error number
 676          * @see http://www.php.net/mysql_errno
 677          *
 678          * @return int
 679          */
 680         abstract function lastErrno();
 681
 682         /**
 683          * Get a description of the last error
 684          * @see http://www.php.net/mysql_error
 685          *
 686          * @return string
 687          */
 688         abstract function lastError();
 689
 690         /**
 691          * mysql_fetch_field() wrapper
 692          * Returns false if the field doesn't exist
 693          *
 694          * @param string $table Table name
 695          * @param string $field Field name
 696          *
 697          * @return Field
 698          */
 699         abstract function fieldInfo( $table, $field );
 700
 701         /**
 702          * Get information about an index into an object
 703          * @param string $table Table name
 704          * @param string $index Index name
 705          * @param string $fname Calling function name
 706          * @return mixed Database-specific index description class or false if the index does not exist
 707          */
 708         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 709
 710         /**
 711          * Get the number of rows affected by the last write query
 712          * @see http://www.php.net/mysql_affected_rows
 713          *
 714          * @return int
 715          */
 716         abstract function affectedRows();
 717
 718         /**
 719          * Wrapper for addslashes()
 720          *
 721          * @param string $s String to be slashed.
 722          * @return string Slashed string.
 723          */
 724         abstract function strencode( $s );
 725
 726         /**
 727          * Returns a wikitext link to the DB's website, e.g.,
 728          *   return "[http://www.mysql.com/ MySQL]";
 729          * Should at least contain plain text, if for some reason
 730          * your database has no website.
 731          *
 732          * @return string Wikitext of a link to the server software's web site
 733          */
 734         abstract function getSoftwareLink();
 735
 736         /**
 737          * A string describing the current software version, like from
 738          * mysql_get_server_info().
 739          *
 740          * @return string Version information from the database server.
 741          */
 742         abstract function getServerVersion();
 743
 744         /**
 745          * Constructor.
 746          *
 747          * FIXME: It is possible to construct a Database object with no associated
 748          * connection object, by specifying no parameters to __construct(). This
 749          * feature is deprecated and should be removed.
 750          *
 751          * DatabaseBase subclasses should not be constructed directly in external
 752          * code. DatabaseBase::factory() should be used instead.
 753          *
 754          * @param array $params Parameters passed from DatabaseBase::factory()
 755          */
 756         function __construct( $params = null ) {
 757                 global $wgDBprefix, $wgDBmwschema, $wgCommandLineMode, $wgDebugDBTransactions;
 758
 759                 $this->mTrxAtomicLevels = new SplStack;
 760
 761                 if ( is_array( $params ) ) { // MW 1.22
 762                         $server = $params['host'];
 763                         $user = $params['user'];
 764                         $password = $params['password'];
 765                         $dbName = $params['dbname'];
 766                         $flags = $params['flags'];
 767                         $tablePrefix = $params['tablePrefix'];
 768                         $schema = $params['schema'];
 769                         $foreign = $params['foreign'];
 770                 } else { // legacy calling pattern
 771                         wfDeprecated( __METHOD__ . " method called without parameter array.", "1.23" );
 772                         $args = func_get_args();
 773                         $server = isset( $args[0] ) ? $args[0] : false;
 774                         $user = isset( $args[1] ) ? $args[1] : false;
 775                         $password = isset( $args[2] ) ? $args[2] : false;
 776                         $dbName = isset( $args[3] ) ? $args[3] : false;
 777                         $flags = isset( $args[4] ) ? $args[4] : 0;
 778                         $tablePrefix = isset( $args[5] ) ? $args[5] : 'get from global';
 779                         $schema = 'get from global';
 780                         $foreign = isset( $args[6] ) ? $args[6] : false;
 781                 }
 782
 783                 $this->mFlags = $flags;
 784                 if ( $this->mFlags & DBO_DEFAULT ) {
 785                         if ( $wgCommandLineMode ) {
 786                                 $this->mFlags &= ~DBO_TRX;
 787                                 if ( $wgDebugDBTransactions ) {
 788                                         wfDebug( "Implicit transaction open disabled.\n" );
 789                                 }
 790                         } else {
 791                                 $this->mFlags |= DBO_TRX;
 792                                 if ( $wgDebugDBTransactions ) {
 793                                         wfDebug( "Implicit transaction open enabled.\n" );
 794                                 }
 795                         }
 796                 }
 797
 798                 /** Get the default table prefix*/
 799                 if ( $tablePrefix == 'get from global' ) {
 800                         $this->mTablePrefix = $wgDBprefix;
 801                 } else {
 802                         $this->mTablePrefix = $tablePrefix;
 803                 }
 804
 805                 /** Get the database schema*/
 806                 if ( $schema == 'get from global' ) {
 807                         $this->mSchema = $wgDBmwschema;
 808                 } else {
 809                         $this->mSchema = $schema;
 810                 }
 811
 812                 $this->mForeign = $foreign;
 813
 814                 if ( $user ) {
 815                         $this->open( $server, $user, $password, $dbName );
 816                 }
 817
 818                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 819                 $trxProf = Profiler::instance()->getTransactionProfiler();
 820                 $trxProf->recordConnection( $this->mServer, $this->mDBname, $isMaster );
 821         }
 822
 823         /**
 824          * Called by serialize. Throw an exception when DB connection is serialized.
 825          * This causes problems on some database engines because the connection is
 826          * not restored on unserialize.
 827          */
 828         public function __sleep() {
 829                 throw new MWException( 'Database serialization may cause problems, since ' .
 830                         'the connection is not restored on wakeup.' );
 831         }
 832
 833         /**
 834          * Given a DB type, construct the name of the appropriate child class of
 835          * DatabaseBase. This is designed to replace all of the manual stuff like:
 836          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 837          * as well as validate against the canonical list of DB types we have
 838          *
 839          * This factory function is mostly useful for when you need to connect to a
 840          * database other than the MediaWiki default (such as for external auth,
 841          * an extension, et cetera). Do not use this to connect to the MediaWiki
 842          * database. Example uses in core:
 843          * @see LoadBalancer::reallyOpenConnection()
 844          * @see ForeignDBRepo::getMasterDB()
 845          * @see WebInstallerDBConnect::execute()
 846          *
 847          * @since 1.18
 848          *
 849          * @param string $dbType A possible DB type
 850          * @param array $p An array of options to pass to the constructor.
 851          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 852          * @throws MWException If the database driver or extension cannot be found
 853          * @return DatabaseBase|null DatabaseBase subclass or null
 854          */
 855         final public static function factory( $dbType, $p = array() ) {
 856                 $canonicalDBTypes = array(
 857                         'mysql' => array( 'mysqli', 'mysql' ),
 858                         'postgres' => array(),
 859                         'sqlite' => array(),
 860                         'oracle' => array(),
 861                         'mssql' => array(),
 862                 );
 863
 864                 $driver = false;
 865                 $dbType = strtolower( $dbType );
 866                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 867                         $possibleDrivers = $canonicalDBTypes[$dbType];
 868                         if ( !empty( $p['driver'] ) ) {
 869                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 870                                         $driver = $p['driver'];
 871                                 } else {
 872                                         throw new MWException( __METHOD__ .
 873                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 874                                 }
 875                         } else {
 876                                 foreach ( $possibleDrivers as $posDriver ) {
 877                                         if ( extension_loaded( $posDriver ) ) {
 878                                                 $driver = $posDriver;
 879                                                 break;
 880                                         }
 881                                 }
 882                         }
 883                 } else {
 884                         $driver = $dbType;
 885                 }
 886                 if ( $driver === false ) {
 887                         throw new MWException( __METHOD__ .
 888                                 " no viable database extension found for type '$dbType'" );
 889                 }
 890
 891                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 892                 // and everything else doesn't use a schema (e.g. null)
 893                 // Although postgres and oracle support schemas, we don't use them (yet)
 894                 // to maintain backwards compatibility
 895                 $defaultSchemas = array(
 896                         'mysql' => null,
 897                         'postgres' => null,
 898                         'sqlite' => null,
 899                         'oracle' => null,
 900                         'mssql' => 'get from global',
 901                 );
 902
 903                 $class = 'Database' . ucfirst( $driver );
 904                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 905                         $params = array(
 906                                 'host' => isset( $p['host'] ) ? $p['host'] : false,
 907                                 'user' => isset( $p['user'] ) ? $p['user'] : false,
 908                                 'password' => isset( $p['password'] ) ? $p['password'] : false,
 909                                 'dbname' => isset( $p['dbname'] ) ? $p['dbname'] : false,
 910                                 'flags' => isset( $p['flags'] ) ? $p['flags'] : 0,
 911                                 'tablePrefix' => isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global',
 912                                 'schema' => isset( $p['schema'] ) ? $p['schema'] : $defaultSchemas[$dbType],
 913                                 'foreign' => isset( $p['foreign'] ) ? $p['foreign'] : false
 914                         );
 915
 916                         return new $class( $params );
 917                 } else {
 918                         return null;
 919                 }
 920         }
 921
 922         protected function installErrorHandler() {
 923                 $this->mPHPError = false;
 924                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 925                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 926         }
 927
 928         /**
 929          * @return bool|string
 930          */
 931         protected function restoreErrorHandler() {
 932                 restore_error_handler();
 933                 if ( $this->htmlErrors !== false ) {
 934                         ini_set( 'html_errors', $this->htmlErrors );
 935                 }
 936                 if ( $this->mPHPError ) {
 937                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 938                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 939
 940                         return $error;
 941                 } else {
 942                         return false;
 943                 }
 944         }
 945
 946         /**
 947          * @param int $errno
 948          * @param string $errstr
 949          */
 950         public function connectionErrorHandler( $errno, $errstr ) {
 951                 $this->mPHPError = $errstr;
 952         }
 953
 954         /**
 955          * Create a log context to pass to wfLogDBError or other logging functions.
 956          *
 957          * @param array $extras Additional data to add to context
 958          * @return array
 959          */
 960         protected function getLogContext( array $extras = array() ) {
 961                 return array_merge(
 962                         array(
 963                                 'db_server' => $this->mServer,
 964                                 'db_name' => $this->mDBname,
 965                                 'db_user' => $this->mUser,
 966                         ),
 967                         $extras
 968                 );
 969         }
 970
 971         /**
 972          * Closes a database connection.
 973          * if it is open : commits any open transactions
 974          *
 975          * @throws MWException
 976          * @return bool Operation success. true if already closed.
 977          */
 978         public function close() {
 979                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 980                         throw new MWException( "Transaction idle callbacks still pending." );
 981                 }
 982                 if ( $this->mConn ) {
 983                         if ( $this->trxLevel() ) {
 984                                 if ( !$this->mTrxAutomatic ) {
 985                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 986                                                 " performing implicit commit before closing connection!" );
 987                                 }
 988
 989                                 $this->commit( __METHOD__, 'flush' );
 990                         }
 991
 992                         $closed = $this->closeConnection();
 993                         $this->mConn = false;
 994                 } else {
 995                         $closed = true;
 996                 }
 997                 $this->mOpened = false;
 998
 999                 return $closed;
1000         }
1001
1002         /**
1003          * Closes underlying database connection
1004          * @since 1.20
1005          * @return bool Whether connection was closed successfully
1006          */
1007         abstract protected function closeConnection();
1008
1009         /**
1010          * @param string $error Fallback error message, used if none is given by DB
1011          * @throws DBConnectionError
1012          */
1013         function reportConnectionError( $error = 'Unknown error' ) {
1014                 $myError = $this->lastError();
1015                 if ( $myError ) {
1016                         $error = $myError;
1017                 }
1018
1019                 # New method
1020                 throw new DBConnectionError( $this, $error );
1021         }
1022
1023         /**
1024          * The DBMS-dependent part of query()
1025          *
1026          * @param string $sql SQL query.
1027          * @return ResultWrapper|bool Result object to feed to fetchObject,
1028          *   fetchRow, ...; or false on failure
1029          */
1030         abstract protected function doQuery( $sql );
1031
1032         /**
1033          * Determine whether a query writes to the DB.
1034          * Should return true if unsure.
1035          *
1036          * @param string $sql
1037          * @return bool
1038          */
1039         public function isWriteQuery( $sql ) {
1040                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1041         }
1042
1043         /**
1044          * Determine whether a SQL statement is sensitive to isolation level.
1045          * A SQL statement is considered transactable if its result could vary
1046          * depending on the transaction isolation level. Operational commands
1047          * such as 'SET' and 'SHOW' are not considered to be transactable.
1048          *
1049          * @param string $sql
1050          * @return bool
1051          */
1052         public function isTransactableQuery( $sql ) {
1053                 $verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
1054                 return !in_array( $verb, array( 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ) );
1055         }
1056
1057         /**
1058          * Run an SQL query and return the result. Normally throws a DBQueryError
1059          * on failure. If errors are ignored, returns false instead.
1060          *
1061          * In new code, the query wrappers select(), insert(), update(), delete(),
1062          * etc. should be used where possible, since they give much better DBMS
1063          * independence and automatically quote or validate user input in a variety
1064          * of contexts. This function is generally only useful for queries which are
1065          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
1066          * as CREATE TABLE.
1067          *
1068          * However, the query wrappers themselves should call this function.
1069          *
1070          * @param string $sql SQL query
1071          * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
1072          *     comment (you can use __METHOD__ or add some extra info)
1073          * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
1074          *     maybe best to catch the exception instead?
1075          * @throws MWException
1076          * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
1077          *     for a successful read query, or false on failure if $tempIgnore set
1078          */
1079         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1080                 global $wgUser, $wgDebugDBTransactions, $wgDebugDumpSqlLength;
1081
1082                 $this->mLastQuery = $sql;
1083
1084                 $isWriteQuery = $this->isWriteQuery( $sql );
1085                 if ( $isWriteQuery ) {
1086                         if ( !$this->mDoneWrites ) {
1087                                 wfDebug( __METHOD__ . ': Writes done: ' .
1088                                         DatabaseBase::generalizeSQL( $sql ) . "\n" );
1089                         }
1090                         # Set a flag indicating that writes have been done
1091                         $this->mDoneWrites = microtime( true );
1092                 }
1093
1094                 # Add a comment for easy SHOW PROCESSLIST interpretation
1095                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
1096                         $userName = $wgUser->getName();
1097                         if ( mb_strlen( $userName ) > 15 ) {
1098                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
1099                         }
1100                         $userName = str_replace( '/', '', $userName );
1101                 } else {
1102                         $userName = '';
1103                 }
1104
1105                 // Add trace comment to the begin of the sql string, right after the operator.
1106                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
1107                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
1108
1109                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX ) && $this->isTransactableQuery( $sql ) ) {
1110                         if ( $wgDebugDBTransactions ) {
1111                                 wfDebug( "Implicit transaction start.\n" );
1112                         }
1113                         $this->begin( __METHOD__ . " ($fname)" );
1114                         $this->mTrxAutomatic = true;
1115                 }
1116
1117                 # Keep track of whether the transaction has write queries pending
1118                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWriteQuery ) {
1119                         $this->mTrxDoneWrites = true;
1120                         Profiler::instance()->getTransactionProfiler()->transactionWritingIn(
1121                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
1122                 }
1123
1124                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1125                 # generalizeSQL will probably cut down the query to reasonable
1126                 # logging size most of the time. The substr is really just a sanity check.
1127                 if ( $isMaster ) {
1128                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1129                         $totalProf = 'DatabaseBase::query-master';
1130                 } else {
1131                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1132                         $totalProf = 'DatabaseBase::query';
1133                 }
1134                 # Include query transaction state
1135                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1136
1137                 $profiler = Profiler::instance();
1138                 if ( !$profiler instanceof ProfilerStub ) {
1139                         $totalProfSection = $profiler->scopedProfileIn( $totalProf );
1140                         $queryProfSection = $profiler->scopedProfileIn( $queryProf );
1141                 }
1142
1143                 if ( $this->debug() ) {
1144                         static $cnt = 0;
1145
1146                         $cnt++;
1147                         $sqlx = $wgDebugDumpSqlLength ? substr( $commentedSql, 0, $wgDebugDumpSqlLength )
1148                                 : $commentedSql;
1149                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
1150
1151                         $master = $isMaster ? 'master' : 'slave';
1152                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
1153                 }
1154
1155                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
1156
1157                 # Avoid fatals if close() was called
1158                 if ( !$this->isOpen() ) {
1159                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
1160                 }
1161
1162                 # Do the query and handle errors
1163                 $startTime = microtime( true );
1164                 $ret = $this->doQuery( $commentedSql );
1165                 # Log the query time and feed it into the DB trx profiler
1166                 $profiler->getTransactionProfiler()->recordQueryCompletion(
1167                         $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
1168
1169                 MWDebug::queryTime( $queryId );
1170
1171                 # Try reconnecting if the connection was lost
1172                 if ( false === $ret && $this->wasErrorReissuable() ) {
1173                         # Transaction is gone, like it or not
1174                         $hadTrx = $this->mTrxLevel; // possible lost transaction
1175                         $this->mTrxLevel = 0;
1176                         $this->mTrxIdleCallbacks = array(); // bug 65263
1177                         $this->mTrxPreCommitCallbacks = array(); // bug 65263
1178                         wfDebug( "Connection lost, reconnecting...\n" );
1179                         # Stash the last error values since ping() might clear them
1180                         $lastError = $this->lastError();
1181                         $lastErrno = $this->lastErrno();
1182                         if ( $this->ping() ) {
1183                                 wfDebug( "Reconnected\n" );
1184                                 $server = $this->getServer();
1185                                 $msg = __METHOD__ . ": lost connection to $server; reconnected";
1186                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
1187
1188                                 if ( $hadTrx ) {
1189                                         # Leave $ret as false and let an error be reported.
1190                                         # Callers may catch the exception and continue to use the DB.
1191                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1192                                 } else {
1193                                         # Should be safe to silently retry (no trx and thus no callbacks)
1194                                         $startTime = microtime( true );
1195                                         $ret = $this->doQuery( $commentedSql );
1196                                         # Log the query time and feed it into the DB trx profiler
1197                                         $profiler->getTransactionProfiler()->recordQueryCompletion(
1198                                                 $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
1199                                 }
1200                         } else {
1201                                 wfDebug( "Failed\n" );
1202                         }
1203                 }
1204
1205                 if ( false === $ret ) {
1206                         $this->reportQueryError(
1207                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1208                 }
1209
1210                 $res = $this->resultObject( $ret );
1211
1212                 // Destroy profile sections in the opposite order to their creation
1213                 $queryProfSection = false;
1214                 $totalProfSection = false;
1215
1216                 return $res;
1217         }
1218
1219         /**
1220          * Report a query error. Log the error, and if neither the object ignore
1221          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1222          *
1223          * @param string $error
1224          * @param int $errno
1225          * @param string $sql
1226          * @param string $fname
1227          * @param bool $tempIgnore
1228          * @throws DBQueryError
1229          */
1230         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1231                 # Ignore errors during error handling to avoid infinite recursion
1232                 $ignore = $this->ignoreErrors( true );
1233                 ++$this->mErrorCount;
1234
1235                 if ( $ignore || $tempIgnore ) {
1236                         wfDebug( "SQL ERROR (ignored): $error\n" );
1237                         $this->ignoreErrors( $ignore );
1238                 } else {
1239                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1240                         wfLogDBError(
1241                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1242                                 $this->getLogContext( array(
1243                                         'method' => __METHOD__,
1244                                         'errno' => $errno,
1245                                         'error' => $error,
1246                                         'sql1line' => $sql1line,
1247                                         'fname' => $fname,
1248                                 ) )
1249                         );
1250                         wfDebug( "SQL ERROR: " . $error . "\n" );
1251                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1252                 }
1253         }
1254
1255         /**
1256          * Intended to be compatible with the PEAR::DB wrapper functions.
1257          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1258          *
1259          * ? = scalar value, quoted as necessary
1260          * ! = raw SQL bit (a function for instance)
1261          * & = filename; reads the file and inserts as a blob
1262          *     (we don't use this though...)
1263          *
1264          * @param string $sql
1265          * @param string $func
1266          *
1267          * @return array
1268          */
1269         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1270                 /* MySQL doesn't support prepared statements (yet), so just
1271                  * pack up the query for reference. We'll manually replace
1272                  * the bits later.
1273                  */
1274                 return array( 'query' => $sql, 'func' => $func );
1275         }
1276
1277         /**
1278          * Free a prepared query, generated by prepare().
1279          * @param string $prepared
1280          */
1281         protected function freePrepared( $prepared ) {
1282                 /* No-op by default */
1283         }
1284
1285         /**
1286          * Execute a prepared query with the various arguments
1287          * @param string $prepared The prepared sql
1288          * @param mixed $args Either an array here, or put scalars as varargs
1289          *
1290          * @return ResultWrapper
1291          */
1292         public function execute( $prepared, $args = null ) {
1293                 if ( !is_array( $args ) ) {
1294                         # Pull the var args
1295                         $args = func_get_args();
1296                         array_shift( $args );
1297                 }
1298
1299                 $sql = $this->fillPrepared( $prepared['query'], $args );
1300
1301                 return $this->query( $sql, $prepared['func'] );
1302         }
1303
1304         /**
1305          * For faking prepared SQL statements on DBs that don't support it directly.
1306          *
1307          * @param string $preparedQuery A 'preparable' SQL statement
1308          * @param array $args Array of Arguments to fill it with
1309          * @return string Executable SQL
1310          */
1311         public function fillPrepared( $preparedQuery, $args ) {
1312                 reset( $args );
1313                 $this->preparedArgs =& $args;
1314
1315                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1316                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1317         }
1318
1319         /**
1320          * preg_callback func for fillPrepared()
1321          * The arguments should be in $this->preparedArgs and must not be touched
1322          * while we're doing this.
1323          *
1324          * @param array $matches
1325          * @throws DBUnexpectedError
1326          * @return string
1327          */
1328         protected function fillPreparedArg( $matches ) {
1329                 switch ( $matches[1] ) {
1330                         case '\\?':
1331                                 return '?';
1332                         case '\\!':
1333                                 return '!';
1334                         case '\\&':
1335                                 return '&';
1336                 }
1337
1338                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1339
1340                 switch ( $matches[1] ) {
1341                         case '?':
1342                                 return $this->addQuotes( $arg );
1343                         case '!':
1344                                 return $arg;
1345                         case '&':
1346                                 # return $this->addQuotes( file_get_contents( $arg ) );
1347                                 throw new DBUnexpectedError(
1348                                         $this,
1349                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1350                                 );
1351                         default:
1352                                 throw new DBUnexpectedError(
1353                                         $this,
1354                                         'Received invalid match. This should never happen!'
1355                                 );
1356                 }
1357         }
1358
1359         /**
1360          * Free a result object returned by query() or select(). It's usually not
1361          * necessary to call this, just use unset() or let the variable holding
1362          * the result object go out of scope.
1363          *
1364          * @param mixed $res A SQL result
1365          */
1366         public function freeResult( $res ) {
1367         }
1368
1369         /**
1370          * A SELECT wrapper which returns a single field from a single result row.
1371          *
1372          * Usually throws a DBQueryError on failure. If errors are explicitly
1373          * ignored, returns false on failure.
1374          *
1375          * If no result rows are returned from the query, false is returned.
1376          *
1377          * @param string|array $table Table name. See DatabaseBase::select() for details.
1378          * @param string $var The field name to select. This must be a valid SQL
1379          *   fragment: do not use unvalidated user input.
1380          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1381          * @param string $fname The function name of the caller.
1382          * @param string|array $options The query options. See DatabaseBase::select() for details.
1383          *
1384          * @return bool|mixed The value from the field, or false on failure.
1385          */
1386         public function selectField(
1387                 $table, $var, $cond = '', $fname = __METHOD__, $options = array()
1388         ) {
1389                 if ( $var === '*' ) { // sanity
1390                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1391                 }
1392
1393                 if ( !is_array( $options ) ) {
1394                         $options = array( $options );
1395                 }
1396
1397                 $options['LIMIT'] = 1;
1398
1399                 $res = $this->select( $table, $var, $cond, $fname, $options );
1400                 if ( $res === false || !$this->numRows( $res ) ) {
1401                         return false;
1402                 }
1403
1404                 $row = $this->fetchRow( $res );
1405
1406                 if ( $row !== false ) {
1407                         return reset( $row );
1408                 } else {
1409                         return false;
1410                 }
1411         }
1412
1413         /**
1414          * A SELECT wrapper which returns a list of single field values from result rows.
1415          *
1416          * Usually throws a DBQueryError on failure. If errors are explicitly
1417          * ignored, returns false on failure.
1418          *
1419          * If no result rows are returned from the query, false is returned.
1420          *
1421          * @param string|array $table Table name. See DatabaseBase::select() for details.
1422          * @param string $var The field name to select. This must be a valid SQL
1423          *   fragment: do not use unvalidated user input.
1424          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1425          * @param string $fname The function name of the caller.
1426          * @param string|array $options The query options. See DatabaseBase::select() for details.
1427          *
1428          * @return bool|array The values from the field, or false on failure
1429          * @since 1.25
1430          */
1431         public function selectFieldValues(
1432                 $table, $var, $cond = '', $fname = __METHOD__, $options = array()
1433         ) {
1434                 if ( $var === '*' ) { // sanity
1435                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1436                 }
1437
1438                 if ( !is_array( $options ) ) {
1439                         $options = array( $options );
1440                 }
1441
1442                 $res = $this->select( $table, $var, $cond, $fname, $options );
1443                 if ( $res === false ) {
1444                         return false;
1445                 }
1446
1447                 $values = array();
1448                 foreach ( $res as $row ) {
1449                         $values[] = $row->$var;
1450                 }
1451
1452                 return $values;
1453         }
1454
1455         /**
1456          * Returns an optional USE INDEX clause to go after the table, and a
1457          * string to go at the end of the query.
1458          *
1459          * @param array $options Associative array of options to be turned into
1460          *   an SQL query, valid keys are listed in the function.
1461          * @return array
1462          * @see DatabaseBase::select()
1463          */
1464         public function makeSelectOptions( $options ) {
1465                 $preLimitTail = $postLimitTail = '';
1466                 $startOpts = '';
1467
1468                 $noKeyOptions = array();
1469
1470                 foreach ( $options as $key => $option ) {
1471                         if ( is_numeric( $key ) ) {
1472                                 $noKeyOptions[$option] = true;
1473                         }
1474                 }
1475
1476                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1477
1478                 $preLimitTail .= $this->makeOrderBy( $options );
1479
1480                 // if (isset($options['LIMIT'])) {
1481                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1482                 //              isset($options['OFFSET']) ? $options['OFFSET']
1483                 //              : false);
1484                 // }
1485
1486                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1487                         $postLimitTail .= ' FOR UPDATE';
1488                 }
1489
1490                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1491                         $postLimitTail .= ' LOCK IN SHARE MODE';
1492                 }
1493
1494                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1495                         $startOpts .= 'DISTINCT';
1496                 }
1497
1498                 # Various MySQL extensions
1499                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1500                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1501                 }
1502
1503                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1504                         $startOpts .= ' HIGH_PRIORITY';
1505                 }
1506
1507                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1508                         $startOpts .= ' SQL_BIG_RESULT';
1509                 }
1510
1511                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1512                         $startOpts .= ' SQL_BUFFER_RESULT';
1513                 }
1514
1515                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1516                         $startOpts .= ' SQL_SMALL_RESULT';
1517                 }
1518
1519                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1520                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1521                 }
1522
1523                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1524                         $startOpts .= ' SQL_CACHE';
1525                 }
1526
1527                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1528                         $startOpts .= ' SQL_NO_CACHE';
1529                 }
1530
1531                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1532                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1533                 } else {
1534                         $useIndex = '';
1535                 }
1536
1537                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1538         }
1539
1540         /**
1541          * Returns an optional GROUP BY with an optional HAVING
1542          *
1543          * @param array $options Associative array of options
1544          * @return string
1545          * @see DatabaseBase::select()
1546          * @since 1.21
1547          */
1548         public function makeGroupByWithHaving( $options ) {
1549                 $sql = '';
1550                 if ( isset( $options['GROUP BY'] ) ) {
1551                         $gb = is_array( $options['GROUP BY'] )
1552                                 ? implode( ',', $options['GROUP BY'] )
1553                                 : $options['GROUP BY'];
1554                         $sql .= ' GROUP BY ' . $gb;
1555                 }
1556                 if ( isset( $options['HAVING'] ) ) {
1557                         $having = is_array( $options['HAVING'] )
1558                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1559                                 : $options['HAVING'];
1560                         $sql .= ' HAVING ' . $having;
1561                 }
1562
1563                 return $sql;
1564         }
1565
1566         /**
1567          * Returns an optional ORDER BY
1568          *
1569          * @param array $options Associative array of options
1570          * @return string
1571          * @see DatabaseBase::select()
1572          * @since 1.21
1573          */
1574         public function makeOrderBy( $options ) {
1575                 if ( isset( $options['ORDER BY'] ) ) {
1576                         $ob = is_array( $options['ORDER BY'] )
1577                                 ? implode( ',', $options['ORDER BY'] )
1578                                 : $options['ORDER BY'];
1579
1580                         return ' ORDER BY ' . $ob;
1581                 }
1582
1583                 return '';
1584         }
1585
1586         /**
1587          * Execute a SELECT query constructed using the various parameters provided.
1588          * See below for full details of the parameters.
1589          *
1590          * @param string|array $table Table name
1591          * @param string|array $vars Field names
1592          * @param string|array $conds Conditions
1593          * @param string $fname Caller function name
1594          * @param array $options Query options
1595          * @param array $join_conds Join conditions
1596          *
1597          *
1598          * @param string|array $table
1599          *
1600          * May be either an array of table names, or a single string holding a table
1601          * name. If an array is given, table aliases can be specified, for example:
1602          *
1603          *    array( 'a' => 'user' )
1604          *
1605          * This includes the user table in the query, with the alias "a" available
1606          * for use in field names (e.g. a.user_name).
1607          *
1608          * All of the table names given here are automatically run through
1609          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1610          * added, and various other table name mappings to be performed.
1611          *
1612          *
1613          * @param string|array $vars
1614          *
1615          * May be either a field name or an array of field names. The field names
1616          * can be complete fragments of SQL, for direct inclusion into the SELECT
1617          * query. If an array is given, field aliases can be specified, for example:
1618          *
1619          *   array( 'maxrev' => 'MAX(rev_id)' )
1620          *
1621          * This includes an expression with the alias "maxrev" in the query.
1622          *
1623          * If an expression is given, care must be taken to ensure that it is
1624          * DBMS-independent.
1625          *
1626          *
1627          * @param string|array $conds
1628          *
1629          * May be either a string containing a single condition, or an array of
1630          * conditions. If an array is given, the conditions constructed from each
1631          * element are combined with AND.
1632          *
1633          * Array elements may take one of two forms:
1634          *
1635          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1636          *   - Elements with a string key are interpreted as equality conditions,
1637          *     where the key is the field name.
1638          *     - If the value of such an array element is a scalar (such as a
1639          *       string), it will be treated as data and thus quoted appropriately.
1640          *       If it is null, an IS NULL clause will be added.
1641          *     - If the value is an array, an IN (...) clause will be constructed
1642          *       from its non-null elements, and an IS NULL clause will be added
1643          *       if null is present, such that the field may match any of the
1644          *       elements in the array. The non-null elements will be quoted.
1645          *
1646          * Note that expressions are often DBMS-dependent in their syntax.
1647          * DBMS-independent wrappers are provided for constructing several types of
1648          * expression commonly used in condition queries. See:
1649          *    - DatabaseBase::buildLike()
1650          *    - DatabaseBase::conditional()
1651          *
1652          *
1653          * @param string|array $options
1654          *
1655          * Optional: Array of query options. Boolean options are specified by
1656          * including them in the array as a string value with a numeric key, for
1657          * example:
1658          *
1659          *    array( 'FOR UPDATE' )
1660          *
1661          * The supported options are:
1662          *
1663          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1664          *     with LIMIT can theoretically be used for paging through a result set,
1665          *     but this is discouraged in MediaWiki for performance reasons.
1666          *
1667          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1668          *     and then the first rows are taken until the limit is reached. LIMIT
1669          *     is applied to a result set after OFFSET.
1670          *
1671          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1672          *     changed until the next COMMIT.
1673          *
1674          *   - DISTINCT: Boolean: return only unique result rows.
1675          *
1676          *   - GROUP BY: May be either an SQL fragment string naming a field or
1677          *     expression to group by, or an array of such SQL fragments.
1678          *
1679          *   - HAVING: May be either an string containing a HAVING clause or an array of
1680          *     conditions building the HAVING clause. If an array is given, the conditions
1681          *     constructed from each element are combined with AND.
1682          *
1683          *   - ORDER BY: May be either an SQL fragment giving a field name or
1684          *     expression to order by, or an array of such SQL fragments.
1685          *
1686          *   - USE INDEX: This may be either a string giving the index name to use
1687          *     for the query, or an array. If it is an associative array, each key
1688          *     gives the table name (or alias), each value gives the index name to
1689          *     use for that table. All strings are SQL fragments and so should be
1690          *     validated by the caller.
1691          *
1692          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1693          *     instead of SELECT.
1694          *
1695          * And also the following boolean MySQL extensions, see the MySQL manual
1696          * for documentation:
1697          *
1698          *    - LOCK IN SHARE MODE
1699          *    - STRAIGHT_JOIN
1700          *    - HIGH_PRIORITY
1701          *    - SQL_BIG_RESULT
1702          *    - SQL_BUFFER_RESULT
1703          *    - SQL_SMALL_RESULT
1704          *    - SQL_CALC_FOUND_ROWS
1705          *    - SQL_CACHE
1706          *    - SQL_NO_CACHE
1707          *
1708          *
1709          * @param string|array $join_conds
1710          *
1711          * Optional associative array of table-specific join conditions. In the
1712          * most common case, this is unnecessary, since the join condition can be
1713          * in $conds. However, it is useful for doing a LEFT JOIN.
1714          *
1715          * The key of the array contains the table name or alias. The value is an
1716          * array with two elements, numbered 0 and 1. The first gives the type of
1717          * join, the second is an SQL fragment giving the join condition for that
1718          * table. For example:
1719          *
1720          *    array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )
1721          *
1722          * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
1723          *   with no rows in it will be returned. If there was a query error, a
1724          *   DBQueryError exception will be thrown, except if the "ignore errors"
1725          *   option was set, in which case false will be returned.
1726          */
1727         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1728                 $options = array(), $join_conds = array() ) {
1729                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1730
1731                 return $this->query( $sql, $fname );
1732         }
1733
1734         /**
1735          * The equivalent of DatabaseBase::select() except that the constructed SQL
1736          * is returned, instead of being immediately executed. This can be useful for
1737          * doing UNION queries, where the SQL text of each query is needed. In general,
1738          * however, callers outside of Database classes should just use select().
1739          *
1740          * @param string|array $table Table name
1741          * @param string|array $vars Field names
1742          * @param string|array $conds Conditions
1743          * @param string $fname Caller function name
1744          * @param string|array $options Query options
1745          * @param string|array $join_conds Join conditions
1746          *
1747          * @return string SQL query string.
1748          * @see DatabaseBase::select()
1749          */
1750         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1751                 $options = array(), $join_conds = array()
1752         ) {
1753                 if ( is_array( $vars ) ) {
1754                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1755                 }
1756
1757                 $options = (array)$options;
1758                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1759                         ? $options['USE INDEX']
1760                         : array();
1761
1762                 if ( is_array( $table ) ) {
1763                         $from = ' FROM ' .
1764                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1765                 } elseif ( $table != '' ) {
1766                         if ( $table[0] == ' ' ) {
1767                                 $from = ' FROM ' . $table;
1768                         } else {
1769                                 $from = ' FROM ' .
1770                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1771                         }
1772                 } else {
1773                         $from = '';
1774                 }
1775
1776                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1777                         $this->makeSelectOptions( $options );
1778
1779                 if ( !empty( $conds ) ) {
1780                         if ( is_array( $conds ) ) {
1781                                 $conds = $this->makeList( $conds, LIST_AND );
1782                         }
1783                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1784                 } else {
1785                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1786                 }
1787
1788                 if ( isset( $options['LIMIT'] ) ) {
1789                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1790                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1791                 }
1792                 $sql = "$sql $postLimitTail";
1793
1794                 if ( isset( $options['EXPLAIN'] ) ) {
1795                         $sql = 'EXPLAIN ' . $sql;
1796                 }
1797
1798                 return $sql;
1799         }
1800
1801         /**
1802          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1803          * that a single row object is returned. If the query returns no rows,
1804          * false is returned.
1805          *
1806          * @param string|array $table Table name
1807          * @param string|array $vars Field names
1808          * @param array $conds Conditions
1809          * @param string $fname Caller function name
1810          * @param string|array $options Query options
1811          * @param array|string $join_conds Join conditions
1812          *
1813          * @return stdClass|bool
1814          */
1815         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1816                 $options = array(), $join_conds = array()
1817         ) {
1818                 $options = (array)$options;
1819                 $options['LIMIT'] = 1;
1820                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1821
1822                 if ( $res === false ) {
1823                         return false;
1824                 }
1825
1826                 if ( !$this->numRows( $res ) ) {
1827                         return false;
1828                 }
1829
1830                 $obj = $this->fetchObject( $res );
1831
1832                 return $obj;
1833         }
1834
1835         /**
1836          * Estimate the number of rows in dataset
1837          *
1838          * MySQL allows you to estimate the number of rows that would be returned
1839          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1840          * index cardinality statistics, and is notoriously inaccurate, especially
1841          * when large numbers of rows have recently been added or deleted.
1842          *
1843          * For DBMSs that don't support fast result size estimation, this function
1844          * will actually perform the SELECT COUNT(*).
1845          *
1846          * Takes the same arguments as DatabaseBase::select().
1847          *
1848          * @param string $table Table name
1849          * @param string $vars Unused
1850          * @param array|string $conds Filters on the table
1851          * @param string $fname Function name for profiling
1852          * @param array $options Options for select
1853          * @return int Row count
1854          */
1855         public function estimateRowCount(
1856                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
1857         ) {
1858                 $rows = 0;
1859                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1860
1861                 if ( $res ) {
1862                         $row = $this->fetchRow( $res );
1863                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1864                 }
1865
1866                 return $rows;
1867         }
1868
1869         /**
1870          * Get the number of rows in dataset
1871          *
1872          * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
1873          *
1874          * Takes the same arguments as DatabaseBase::select().
1875          *
1876          * @param string $table Table name
1877          * @param string $vars Unused
1878          * @param array|string $conds Filters on the table
1879          * @param string $fname Function name for profiling
1880          * @param array $options Options for select
1881          * @return int Row count
1882          * @since 1.24
1883          */
1884         public function selectRowCount(
1885                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
1886         ) {
1887                 $rows = 0;
1888                 $sql = $this->selectSQLText( $table, '1', $conds, $fname, $options );
1889                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count" );
1890
1891                 if ( $res ) {
1892                         $row = $this->fetchRow( $res );
1893                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1894                 }
1895
1896                 return $rows;
1897         }
1898
1899         /**
1900          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1901          * It's only slightly flawed. Don't use for anything important.
1902          *
1903          * @param string $sql A SQL Query
1904          *
1905          * @return string
1906          */
1907         static function generalizeSQL( $sql ) {
1908                 # This does the same as the regexp below would do, but in such a way
1909                 # as to avoid crashing php on some large strings.
1910                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1911
1912                 $sql = str_replace( "\\\\", '', $sql );
1913                 $sql = str_replace( "\\'", '', $sql );
1914                 $sql = str_replace( "\\\"", '', $sql );
1915                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1916                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1917
1918                 # All newlines, tabs, etc replaced by single space
1919                 $sql = preg_replace( '/\s+/', ' ', $sql );
1920
1921                 # All numbers => N,
1922                 # except the ones surrounded by characters, e.g. l10n
1923                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1924                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1925
1926                 return $sql;
1927         }
1928
1929         /**
1930          * Determines whether a field exists in a table
1931          *
1932          * @param string $table Table name
1933          * @param string $field Filed to check on that table
1934          * @param string $fname Calling function name (optional)
1935          * @return bool Whether $table has filed $field
1936          */
1937         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1938                 $info = $this->fieldInfo( $table, $field );
1939
1940                 return (bool)$info;
1941         }
1942
1943         /**
1944          * Determines whether an index exists
1945          * Usually throws a DBQueryError on failure
1946          * If errors are explicitly ignored, returns NULL on failure
1947          *
1948          * @param string $table
1949          * @param string $index
1950          * @param string $fname
1951          * @return bool|null
1952          */
1953         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1954                 if ( !$this->tableExists( $table ) ) {
1955                         return null;
1956                 }
1957
1958                 $info = $this->indexInfo( $table, $index, $fname );
1959                 if ( is_null( $info ) ) {
1960                         return null;
1961                 } else {
1962                         return $info !== false;
1963                 }
1964         }
1965
1966         /**
1967          * Query whether a given table exists
1968          *
1969          * @param string $table
1970          * @param string $fname
1971          * @return bool
1972          */
1973         public function tableExists( $table, $fname = __METHOD__ ) {
1974                 $table = $this->tableName( $table );
1975                 $old = $this->ignoreErrors( true );
1976                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1977                 $this->ignoreErrors( $old );
1978
1979                 return (bool)$res;
1980         }
1981
1982         /**
1983          * Determines if a given index is unique
1984          *
1985          * @param string $table
1986          * @param string $index
1987          *
1988          * @return bool
1989          */
1990         public function indexUnique( $table, $index ) {
1991                 $indexInfo = $this->indexInfo( $table, $index );
1992
1993                 if ( !$indexInfo ) {
1994                         return null;
1995                 }
1996
1997                 return !$indexInfo[0]->Non_unique;
1998         }
1999
2000         /**
2001          * Helper for DatabaseBase::insert().
2002          *
2003          * @param array $options
2004          * @return string
2005          */
2006         protected function makeInsertOptions( $options ) {
2007                 return implode( ' ', $options );
2008         }
2009
2010         /**
2011          * INSERT wrapper, inserts an array into a table.
2012          *
2013          * $a may be either:
2014          *
2015          *   - A single associative array. The array keys are the field names, and
2016          *     the values are the values to insert. The values are treated as data
2017          *     and will be quoted appropriately. If NULL is inserted, this will be
2018          *     converted to a database NULL.
2019          *   - An array with numeric keys, holding a list of associative arrays.
2020          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2021          *     each subarray must be identical to each other, and in the same order.
2022          *
2023          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2024          * returns success.
2025          *
2026          * $options is an array of options, with boolean options encoded as values
2027          * with numeric keys, in the same style as $options in
2028          * DatabaseBase::select(). Supported options are:
2029          *
2030          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
2031          *     any rows which cause duplicate key errors are not inserted. It's
2032          *     possible to determine how many rows were successfully inserted using
2033          *     DatabaseBase::affectedRows().
2034          *
2035          * @param string $table Table name. This will be passed through
2036          *   DatabaseBase::tableName().
2037          * @param array $a Array of rows to insert
2038          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2039          * @param array $options Array of options
2040          *
2041          * @return bool
2042          */
2043         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
2044                 # No rows to insert, easy just return now
2045                 if ( !count( $a ) ) {
2046                         return true;
2047                 }
2048
2049                 $table = $this->tableName( $table );
2050
2051                 if ( !is_array( $options ) ) {
2052                         $options = array( $options );
2053                 }
2054
2055                 $fh = null;
2056                 if ( isset( $options['fileHandle'] ) ) {
2057                         $fh = $options['fileHandle'];
2058                 }
2059                 $options = $this->makeInsertOptions( $options );
2060
2061                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2062                         $multi = true;
2063                         $keys = array_keys( $a[0] );
2064                 } else {
2065                         $multi = false;
2066                         $keys = array_keys( $a );
2067                 }
2068
2069                 $sql = 'INSERT ' . $options .
2070                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2071
2072                 if ( $multi ) {
2073                         $first = true;
2074                         foreach ( $a as $row ) {
2075                                 if ( $first ) {
2076                                         $first = false;
2077                                 } else {
2078                                         $sql .= ',';
2079                                 }
2080                                 $sql .= '(' . $this->makeList( $row ) . ')';
2081                         }
2082                 } else {
2083                         $sql .= '(' . $this->makeList( $a ) . ')';
2084                 }
2085
2086                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2087                         return false;
2088                 } elseif ( $fh !== null ) {
2089                         return true;
2090                 }
2091
2092                 return (bool)$this->query( $sql, $fname );
2093         }
2094
2095         /**
2096          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
2097          *
2098          * @param array $options
2099          * @return array
2100          */
2101         protected function makeUpdateOptionsArray( $options ) {
2102                 if ( !is_array( $options ) ) {
2103                         $options = array( $options );
2104                 }
2105
2106                 $opts = array();
2107
2108                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
2109                         $opts[] = $this->lowPriorityOption();
2110                 }
2111
2112                 if ( in_array( 'IGNORE', $options ) ) {
2113                         $opts[] = 'IGNORE';
2114                 }
2115
2116                 return $opts;
2117         }
2118
2119         /**
2120          * Make UPDATE options for the DatabaseBase::update function
2121          *
2122          * @param array $options The options passed to DatabaseBase::update
2123          * @return string
2124          */
2125         protected function makeUpdateOptions( $options ) {
2126                 $opts = $this->makeUpdateOptionsArray( $options );
2127
2128                 return implode( ' ', $opts );
2129         }
2130
2131         /**
2132          * UPDATE wrapper. Takes a condition array and a SET array.
2133          *
2134          * @param string $table Name of the table to UPDATE. This will be passed through
2135          *   DatabaseBase::tableName().
2136          * @param array $values An array of values to SET. For each array element,
2137          *   the key gives the field name, and the value gives the data to set
2138          *   that field to. The data will be quoted by DatabaseBase::addQuotes().
2139          * @param array $conds An array of conditions (WHERE). See
2140          *   DatabaseBase::select() for the details of the format of condition
2141          *   arrays. Use '*' to update all rows.
2142          * @param string $fname The function name of the caller (from __METHOD__),
2143          *   for logging and profiling.
2144          * @param array $options An array of UPDATE options, can be:
2145          *   - IGNORE: Ignore unique key conflicts
2146          *   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
2147          * @return bool
2148          */
2149         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
2150                 $table = $this->tableName( $table );
2151                 $opts = $this->makeUpdateOptions( $options );
2152                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
2153
2154                 if ( $conds !== array() && $conds !== '*' ) {
2155                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
2156                 }
2157
2158                 return $this->query( $sql, $fname );
2159         }
2160
2161         /**
2162          * Makes an encoded list of strings from an array
2163          *
2164          * @param array $a Containing the data
2165          * @param int $mode Constant
2166          *    - LIST_COMMA: Comma separated, no field names
2167          *    - LIST_AND:   ANDed WHERE clause (without the WHERE). See the
2168          *      documentation for $conds in DatabaseBase::select().
2169          *    - LIST_OR:    ORed WHERE clause (without the WHERE)
2170          *    - LIST_SET:   Comma separated with field names, like a SET clause
2171          *    - LIST_NAMES: Comma separated field names
2172          * @throws MWException|DBUnexpectedError
2173          * @return string
2174          */
2175         public function makeList( $a, $mode = LIST_COMMA ) {
2176                 if ( !is_array( $a ) ) {
2177                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
2178                 }
2179
2180                 $first = true;
2181                 $list = '';
2182
2183                 foreach ( $a as $field => $value ) {
2184                         if ( !$first ) {
2185                                 if ( $mode == LIST_AND ) {
2186                                         $list .= ' AND ';
2187                                 } elseif ( $mode == LIST_OR ) {
2188                                         $list .= ' OR ';
2189                                 } else {
2190                                         $list .= ',';
2191                                 }
2192                         } else {
2193                                 $first = false;
2194                         }
2195
2196                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
2197                                 $list .= "($value)";
2198                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
2199                                 $list .= "$value";
2200                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
2201                                 // Remove null from array to be handled separately if found
2202                                 $includeNull = false;
2203                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2204                                         $includeNull = true;
2205                                         unset( $value[$nullKey] );
2206                                 }
2207                                 if ( count( $value ) == 0 && !$includeNull ) {
2208                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
2209                                 } elseif ( count( $value ) == 0 ) {
2210                                         // only check if $field is null
2211                                         $list .= "$field IS NULL";
2212                                 } else {
2213                                         // IN clause contains at least one valid element
2214                                         if ( $includeNull ) {
2215                                                 // Group subconditions to ensure correct precedence
2216                                                 $list .= '(';
2217                                         }
2218                                         if ( count( $value ) == 1 ) {
2219                                                 // Special-case single values, as IN isn't terribly efficient
2220                                                 // Don't necessarily assume the single key is 0; we don't
2221                                                 // enforce linear numeric ordering on other arrays here.
2222                                                 $value = array_values( $value );
2223                                                 $list .= $field . " = " . $this->addQuotes( $value[0] );
2224                                         } else {
2225                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2226                                         }
2227                                         // if null present in array, append IS NULL
2228                                         if ( $includeNull ) {
2229                                                 $list .= " OR $field IS NULL)";
2230                                         }
2231                                 }
2232                         } elseif ( $value === null ) {
2233                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
2234                                         $list .= "$field IS ";
2235                                 } elseif ( $mode == LIST_SET ) {
2236                                         $list .= "$field = ";
2237                                 }
2238                                 $list .= 'NULL';
2239                         } else {
2240                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
2241                                         $list .= "$field = ";
2242                                 }
2243                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
2244                         }
2245                 }
2246
2247                 return $list;
2248         }
2249
2250         /**
2251          * Build a partial where clause from a 2-d array such as used for LinkBatch.
2252          * The keys on each level may be either integers or strings.
2253          *
2254          * @param array $data Organized as 2-d
2255          *    array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
2256          * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
2257          * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
2258          * @return string|bool SQL fragment, or false if no items in array
2259          */
2260         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2261                 $conds = array();
2262
2263                 foreach ( $data as $base => $sub ) {
2264                         if ( count( $sub ) ) {
2265                                 $conds[] = $this->makeList(
2266                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
2267                                         LIST_AND );
2268                         }
2269                 }
2270
2271                 if ( $conds ) {
2272                         return $this->makeList( $conds, LIST_OR );
2273                 } else {
2274                         // Nothing to search for...
2275                         return false;
2276                 }
2277         }
2278
2279         /**
2280          * Return aggregated value alias
2281          *
2282          * @param array $valuedata
2283          * @param string $valuename
2284          *
2285          * @return string
2286          */
2287         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2288                 return $valuename;
2289         }
2290
2291         /**
2292          * @param string $field
2293          * @return string
2294          */
2295         public function bitNot( $field ) {
2296                 return "(~$field)";
2297         }
2298
2299         /**
2300          * @param string $fieldLeft
2301          * @param string $fieldRight
2302          * @return string
2303          */
2304         public function bitAnd( $fieldLeft, $fieldRight ) {
2305                 return "($fieldLeft & $fieldRight)";
2306         }
2307
2308         /**
2309          * @param string $fieldLeft
2310          * @param string $fieldRight
2311          * @return string
2312          */
2313         public function bitOr( $fieldLeft, $fieldRight ) {
2314                 return "($fieldLeft | $fieldRight)";
2315         }
2316
2317         /**
2318          * Build a concatenation list to feed into a SQL query
2319          * @param array $stringList List of raw SQL expressions; caller is
2320          *   responsible for any quoting
2321          * @return string
2322          */
2323         public function buildConcat( $stringList ) {
2324                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2325         }
2326
2327         /**
2328          * Build a GROUP_CONCAT or equivalent statement for a query.
2329          *
2330          * This is useful for combining a field for several rows into a single string.
2331          * NULL values will not appear in the output, duplicated values will appear,
2332          * and the resulting delimiter-separated values have no defined sort order.
2333          * Code using the results may need to use the PHP unique() or sort() methods.
2334          *
2335          * @param string $delim Glue to bind the results together
2336          * @param string|array $table Table name
2337          * @param string $field Field name
2338          * @param string|array $conds Conditions
2339          * @param string|array $join_conds Join conditions
2340          * @return string SQL text
2341          * @since 1.23
2342          */
2343         public function buildGroupConcatField(
2344                 $delim, $table, $field, $conds = '', $join_conds = array()
2345         ) {
2346                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2347
2348                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, array(), $join_conds ) . ')';
2349         }
2350
2351         /**
2352          * Change the current database
2353          *
2354          * @todo Explain what exactly will fail if this is not overridden.
2355          *
2356          * @param string $db
2357          *
2358          * @return bool Success or failure
2359          */
2360         public function selectDB( $db ) {
2361                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2362                 # if your database engine supports a concept similar to MySQL's
2363                 # databases you may as well.
2364                 $this->mDBname = $db;
2365
2366                 return true;
2367         }
2368
2369         /**
2370          * Get the current DB name
2371          * @return string
2372          */
2373         public function getDBname() {
2374                 return $this->mDBname;
2375         }
2376
2377         /**
2378          * Get the server hostname or IP address
2379          * @return string
2380          */
2381         public function getServer() {
2382                 return $this->mServer;
2383         }
2384
2385         /**
2386          * Format a table name ready for use in constructing an SQL query
2387          *
2388          * This does two important things: it quotes the table names to clean them up,
2389          * and it adds a table prefix if only given a table name with no quotes.
2390          *
2391          * All functions of this object which require a table name call this function
2392          * themselves. Pass the canonical name to such functions. This is only needed
2393          * when calling query() directly.
2394          *
2395          * @param string $name Database table name
2396          * @param string $format One of:
2397          *   quoted - Automatically pass the table name through addIdentifierQuotes()
2398          *            so that it can be used in a query.
2399          *   raw - Do not add identifier quotes to the table name
2400          * @return string Full database name
2401          */
2402         public function tableName( $name, $format = 'quoted' ) {
2403                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
2404                 # Skip the entire process when we have a string quoted on both ends.
2405                 # Note that we check the end so that we will still quote any use of
2406                 # use of `database`.table. But won't break things if someone wants
2407                 # to query a database table with a dot in the name.
2408                 if ( $this->isQuotedIdentifier( $name ) ) {
2409                         return $name;
2410                 }
2411
2412                 # Lets test for any bits of text that should never show up in a table
2413                 # name. Basically anything like JOIN or ON which are actually part of
2414                 # SQL queries, but may end up inside of the table value to combine
2415                 # sql. Such as how the API is doing.
2416                 # Note that we use a whitespace test rather than a \b test to avoid
2417                 # any remote case where a word like on may be inside of a table name
2418                 # surrounded by symbols which may be considered word breaks.
2419                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2420                         return $name;
2421                 }
2422
2423                 # Split database and table into proper variables.
2424                 # We reverse the explode so that database.table and table both output
2425                 # the correct table.
2426                 $dbDetails = explode( '.', $name, 3 );
2427                 if ( count( $dbDetails ) == 3 ) {
2428                         list( $database, $schema, $table ) = $dbDetails;
2429                         # We don't want any prefix added in this case
2430                         $prefix = '';
2431                 } elseif ( count( $dbDetails ) == 2 ) {
2432                         list( $database, $table ) = $dbDetails;
2433                         # We don't want any prefix added in this case
2434                         # In dbs that support it, $database may actually be the schema
2435                         # but that doesn't affect any of the functionality here
2436                         $prefix = '';
2437                         $schema = null;
2438                 } else {
2439                         list( $table ) = $dbDetails;
2440                         if ( $wgSharedDB !== null # We have a shared database
2441                                 && $this->mForeign == false # We're not working on a foreign database
2442                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
2443                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
2444                         ) {
2445                                 $database = $wgSharedDB;
2446                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
2447                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
2448                         } else {
2449                                 $database = null;
2450                                 $schema = $this->mSchema; # Default schema
2451                                 $prefix = $this->mTablePrefix; # Default prefix
2452                         }
2453                 }
2454
2455                 # Quote $table and apply the prefix if not quoted.
2456                 # $tableName might be empty if this is called from Database::replaceVars()
2457                 $tableName = "{$prefix}{$table}";
2458                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
2459                         $tableName = $this->addIdentifierQuotes( $tableName );
2460                 }
2461
2462                 # Quote $schema and merge it with the table name if needed
2463                 if ( $schema !== null ) {
2464                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
2465                                 $schema = $this->addIdentifierQuotes( $schema );
2466                         }
2467                         $tableName = $schema . '.' . $tableName;
2468                 }
2469
2470                 # Quote $database and merge it with the table name if needed
2471                 if ( $database !== null ) {
2472                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
2473                                 $database = $this->addIdentifierQuotes( $database );
2474                         }
2475                         $tableName = $database . '.' . $tableName;
2476                 }
2477
2478                 return $tableName;
2479         }
2480
2481         /**
2482          * Fetch a number of table names into an array
2483          * This is handy when you need to construct SQL for joins
2484          *
2485          * Example:
2486          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
2487          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2488          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2489          *
2490          * @return array
2491          */
2492         public function tableNames() {
2493                 $inArray = func_get_args();
2494                 $retVal = array();
2495
2496                 foreach ( $inArray as $name ) {
2497                         $retVal[$name] = $this->tableName( $name );
2498                 }
2499
2500                 return $retVal;
2501         }
2502
2503         /**
2504          * Fetch a number of table names into an zero-indexed numerical array
2505          * This is handy when you need to construct SQL for joins
2506          *
2507          * Example:
2508          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
2509          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2510          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2511          *
2512          * @return array
2513          */
2514         public function tableNamesN() {
2515                 $inArray = func_get_args();
2516                 $retVal = array();
2517
2518                 foreach ( $inArray as $name ) {
2519                         $retVal[] = $this->tableName( $name );
2520                 }
2521
2522                 return $retVal;
2523         }
2524
2525         /**
2526          * Get an aliased table name
2527          * e.g. tableName AS newTableName
2528          *
2529          * @param string $name Table name, see tableName()
2530          * @param string|bool $alias Alias (optional)
2531          * @return string SQL name for aliased table. Will not alias a table to its own name
2532          */
2533         public function tableNameWithAlias( $name, $alias = false ) {
2534                 if ( !$alias || $alias == $name ) {
2535                         return $this->tableName( $name );
2536                 } else {
2537                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2538                 }
2539         }
2540
2541         /**
2542          * Gets an array of aliased table names
2543          *
2544          * @param array $tables Array( [alias] => table )
2545          * @return string[] See tableNameWithAlias()
2546          */
2547         public function tableNamesWithAlias( $tables ) {
2548                 $retval = array();
2549                 foreach ( $tables as $alias => $table ) {
2550                         if ( is_numeric( $alias ) ) {
2551                                 $alias = $table;
2552                         }
2553                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2554                 }
2555
2556                 return $retval;
2557         }
2558
2559         /**
2560          * Get an aliased field name
2561          * e.g. fieldName AS newFieldName
2562          *
2563          * @param string $name Field name
2564          * @param string|bool $alias Alias (optional)
2565          * @return string SQL name for aliased field. Will not alias a field to its own name
2566          */
2567         public function fieldNameWithAlias( $name, $alias = false ) {
2568                 if ( !$alias || (string)$alias === (string)$name ) {
2569                         return $name;
2570                 } else {
2571                         return $name . ' AS ' . $alias; //PostgreSQL needs AS
2572                 }
2573         }
2574
2575         /**
2576          * Gets an array of aliased field names
2577          *
2578          * @param array $fields Array( [alias] => field )
2579          * @return string[] See fieldNameWithAlias()
2580          */
2581         public function fieldNamesWithAlias( $fields ) {
2582                 $retval = array();
2583                 foreach ( $fields as $alias => $field ) {
2584                         if ( is_numeric( $alias ) ) {
2585                                 $alias = $field;
2586                         }
2587                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2588                 }
2589
2590                 return $retval;
2591         }
2592
2593         /**
2594          * Get the aliased table name clause for a FROM clause
2595          * which might have a JOIN and/or USE INDEX clause
2596          *
2597          * @param array $tables ( [alias] => table )
2598          * @param array $use_index Same as for select()
2599          * @param array $join_conds Same as for select()
2600          * @return string
2601          */
2602         protected function tableNamesWithUseIndexOrJOIN(
2603                 $tables, $use_index = array(), $join_conds = array()
2604         ) {
2605                 $ret = array();
2606                 $retJOIN = array();
2607                 $use_index = (array)$use_index;
2608                 $join_conds = (array)$join_conds;
2609
2610                 foreach ( $tables as $alias => $table ) {
2611                         if ( !is_string( $alias ) ) {
2612                                 // No alias? Set it equal to the table name
2613                                 $alias = $table;
2614                         }
2615                         // Is there a JOIN clause for this table?
2616                         if ( isset( $join_conds[$alias] ) ) {
2617                                 list( $joinType, $conds ) = $join_conds[$alias];
2618                                 $tableClause = $joinType;
2619                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2620                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2621                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2622                                         if ( $use != '' ) {
2623                                                 $tableClause .= ' ' . $use;
2624                                         }
2625                                 }
2626                                 $on = $this->makeList( (array)$conds, LIST_AND );
2627                                 if ( $on != '' ) {
2628                                         $tableClause .= ' ON (' . $on . ')';
2629                                 }
2630
2631                                 $retJOIN[] = $tableClause;
2632                         } elseif ( isset( $use_index[$alias] ) ) {
2633                                 // Is there an INDEX clause for this table?
2634                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2635                                 $tableClause .= ' ' . $this->useIndexClause(
2636                                         implode( ',', (array)$use_index[$alias] )
2637                                 );
2638
2639                                 $ret[] = $tableClause;
2640                         } else {
2641                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2642
2643                                 $ret[] = $tableClause;
2644                         }
2645                 }
2646
2647                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2648                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2649                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2650
2651                 // Compile our final table clause
2652                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
2653         }
2654
2655         /**
2656          * Get the name of an index in a given table.
2657          *
2658          * @protected Don't use outside of DatabaseBase and childs
2659          * @param string $index
2660          * @return string
2661          */
2662         public function indexName( $index ) {
2663                 // @FIXME: Make this protected once we move away from PHP 5.3
2664                 // Needs to be public because of usage in closure (in DatabaseBase::replaceVars)
2665
2666                 // Backwards-compatibility hack
2667                 $renamed = array(
2668                         'ar_usertext_timestamp' => 'usertext_timestamp',
2669                         'un_user_id' => 'user_id',
2670                         'un_user_ip' => 'user_ip',
2671                 );
2672
2673                 if ( isset( $renamed[$index] ) ) {
2674                         return $renamed[$index];
2675                 } else {
2676                         return $index;
2677                 }
2678         }
2679
2680         /**
2681          * Adds quotes and backslashes.
2682          *
2683          * @param string $s
2684          * @return string
2685          */
2686         public function addQuotes( $s ) {
2687                 if ( $s === null ) {
2688                         return 'NULL';
2689                 } else {
2690                         # This will also quote numeric values. This should be harmless,
2691                         # and protects against weird problems that occur when they really
2692                         # _are_ strings such as article titles and string->number->string
2693                         # conversion is not 1:1.
2694                         return "'" . $this->strencode( $s ) . "'";
2695                 }
2696         }
2697
2698         /**
2699          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2700          * MySQL uses `backticks` while basically everything else uses double quotes.
2701          * Since MySQL is the odd one out here the double quotes are our generic
2702          * and we implement backticks in DatabaseMysql.
2703          *
2704          * @param string $s
2705          * @return string
2706          */
2707         public function addIdentifierQuotes( $s ) {
2708                 return '"' . str_replace( '"', '""', $s ) . '"';
2709         }
2710
2711         /**
2712          * Returns if the given identifier looks quoted or not according to
2713          * the database convention for quoting identifiers .
2714          *
2715          * @param string $name
2716          * @return bool
2717          */
2718         public function isQuotedIdentifier( $name ) {
2719                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2720         }
2721
2722         /**
2723          * @param string $s
2724          * @return string
2725          */
2726         protected function escapeLikeInternal( $s ) {
2727                 return addcslashes( $s, '\%_' );
2728         }
2729
2730         /**
2731          * LIKE statement wrapper, receives a variable-length argument list with
2732          * parts of pattern to match containing either string literals that will be
2733          * escaped or tokens returned by anyChar() or anyString(). Alternatively,
2734          * the function could be provided with an array of aforementioned
2735          * parameters.
2736          *
2737          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
2738          * a LIKE clause that searches for subpages of 'My page title'.
2739          * Alternatively:
2740          *   $pattern = array( 'My_page_title/', $dbr->anyString() );
2741          *   $query .= $dbr->buildLike( $pattern );
2742          *
2743          * @since 1.16
2744          * @return string Fully built LIKE statement
2745          */
2746         public function buildLike() {
2747                 $params = func_get_args();
2748
2749                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2750                         $params = $params[0];
2751                 }
2752
2753                 $s = '';
2754
2755                 foreach ( $params as $value ) {
2756                         if ( $value instanceof LikeMatch ) {
2757                                 $s .= $value->toString();
2758                         } else {
2759                                 $s .= $this->escapeLikeInternal( $value );
2760                         }
2761                 }
2762
2763                 return " LIKE {$this->addQuotes( $s )} ";
2764         }
2765
2766         /**
2767          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2768          *
2769          * @return LikeMatch
2770          */
2771         public function anyChar() {
2772                 return new LikeMatch( '_' );
2773         }
2774
2775         /**
2776          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2777          *
2778          * @return LikeMatch
2779          */
2780         public function anyString() {
2781                 return new LikeMatch( '%' );
2782         }
2783
2784         /**
2785          * Returns an appropriately quoted sequence value for inserting a new row.
2786          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2787          * subclass will return an integer, and save the value for insertId()
2788          *
2789          * Any implementation of this function should *not* involve reusing
2790          * sequence numbers created for rolled-back transactions.
2791          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2792          * @param string $seqName
2793          * @return null|int
2794          */
2795         public function nextSequenceValue( $seqName ) {
2796                 return null;
2797         }
2798
2799         /**
2800          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2801          * is only needed because a) MySQL must be as efficient as possible due to
2802          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2803          * which index to pick. Anyway, other databases might have different
2804          * indexes on a given table. So don't bother overriding this unless you're
2805          * MySQL.
2806          * @param string $index
2807          * @return string
2808          */
2809         public function useIndexClause( $index ) {
2810                 return '';
2811         }
2812
2813         /**
2814          * REPLACE query wrapper.
2815          *
2816          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2817          * except that when there is a duplicate key error, the old row is deleted
2818          * and the new row is inserted in its place.
2819          *
2820          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2821          * perform the delete, we need to know what the unique indexes are so that
2822          * we know how to find the conflicting rows.
2823          *
2824          * It may be more efficient to leave off unique indexes which are unlikely
2825          * to collide. However if you do this, you run the risk of encountering
2826          * errors which wouldn't have occurred in MySQL.
2827          *
2828          * @param string $table The table to replace the row(s) in.
2829          * @param array $uniqueIndexes Is an array of indexes. Each element may be either
2830          *    a field name or an array of field names
2831          * @param array $rows Can be either a single row to insert, or multiple rows,
2832          *    in the same format as for DatabaseBase::insert()
2833          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2834          */
2835         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2836                 $quotedTable = $this->tableName( $table );
2837
2838                 if ( count( $rows ) == 0 ) {
2839                         return;
2840                 }
2841
2842                 # Single row case
2843                 if ( !is_array( reset( $rows ) ) ) {
2844                         $rows = array( $rows );
2845                 }
2846
2847                 foreach ( $rows as $row ) {
2848                         # Delete rows which collide
2849                         if ( $uniqueIndexes ) {
2850                                 $sql = "DELETE FROM $quotedTable WHERE ";
2851                                 $first = true;
2852                                 foreach ( $uniqueIndexes as $index ) {
2853                                         if ( $first ) {
2854                                                 $first = false;
2855                                                 $sql .= '( ';
2856                                         } else {
2857                                                 $sql .= ' ) OR ( ';
2858                                         }
2859                                         if ( is_array( $index ) ) {
2860                                                 $first2 = true;
2861                                                 foreach ( $index as $col ) {
2862                                                         if ( $first2 ) {
2863                                                                 $first2 = false;
2864                                                         } else {
2865                                                                 $sql .= ' AND ';
2866                                                         }
2867                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2868                                                 }
2869                                         } else {
2870                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2871                                         }
2872                                 }
2873                                 $sql .= ' )';
2874                                 $this->query( $sql, $fname );
2875                         }
2876
2877                         # Now insert the row
2878                         $this->insert( $table, $row, $fname );
2879                 }
2880         }
2881
2882         /**
2883          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2884          * statement.
2885          *
2886          * @param string $table Table name
2887          * @param array|string $rows Row(s) to insert
2888          * @param string $fname Caller function name
2889          *
2890          * @return ResultWrapper
2891          */
2892         protected function nativeReplace( $table, $rows, $fname ) {
2893                 $table = $this->tableName( $table );
2894
2895                 # Single row case
2896                 if ( !is_array( reset( $rows ) ) ) {
2897                         $rows = array( $rows );
2898                 }
2899
2900                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2901                 $first = true;
2902
2903                 foreach ( $rows as $row ) {
2904                         if ( $first ) {
2905                                 $first = false;
2906                         } else {
2907                                 $sql .= ',';
2908                         }
2909
2910                         $sql .= '(' . $this->makeList( $row ) . ')';
2911                 }
2912
2913                 return $this->query( $sql, $fname );
2914         }
2915
2916         /**
2917          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
2918          *
2919          * This updates any conflicting rows (according to the unique indexes) using
2920          * the provided SET clause and inserts any remaining (non-conflicted) rows.
2921          *
2922          * $rows may be either:
2923          *   - A single associative array. The array keys are the field names, and
2924          *     the values are the values to insert. The values are treated as data
2925          *     and will be quoted appropriately. If NULL is inserted, this will be
2926          *     converted to a database NULL.
2927          *   - An array with numeric keys, holding a list of associative arrays.
2928          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2929          *     each subarray must be identical to each other, and in the same order.
2930          *
2931          * It may be more efficient to leave off unique indexes which are unlikely
2932          * to collide. However if you do this, you run the risk of encountering
2933          * errors which wouldn't have occurred in MySQL.
2934          *
2935          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2936          * returns success.
2937          *
2938          * @since 1.22
2939          *
2940          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
2941          * @param array $rows A single row or list of rows to insert
2942          * @param array $uniqueIndexes List of single field names or field name tuples
2943          * @param array $set An array of values to SET. For each array element, the
2944          *   key gives the field name, and the value gives the data to set that
2945          *   field to. The data will be quoted by DatabaseBase::addQuotes().
2946          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2947          * @throws Exception
2948          * @return bool
2949          */
2950         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2951                 $fname = __METHOD__
2952         ) {
2953                 if ( !count( $rows ) ) {
2954                         return true; // nothing to do
2955                 }
2956
2957                 if ( !is_array( reset( $rows ) ) ) {
2958                         $rows = array( $rows );
2959                 }
2960
2961                 if ( count( $uniqueIndexes ) ) {
2962                         $clauses = array(); // list WHERE clauses that each identify a single row
2963                         foreach ( $rows as $row ) {
2964                                 foreach ( $uniqueIndexes as $index ) {
2965                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2966                                         $rowKey = array(); // unique key to this row
2967                                         foreach ( $index as $column ) {
2968                                                 $rowKey[$column] = $row[$column];
2969                                         }
2970                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2971                                 }
2972                         }
2973                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2974                 } else {
2975                         $where = false;
2976                 }
2977
2978                 $useTrx = !$this->mTrxLevel;
2979                 if ( $useTrx ) {
2980                         $this->begin( $fname );
2981                 }
2982                 try {
2983                         # Update any existing conflicting row(s)
2984                         if ( $where !== false ) {
2985                                 $ok = $this->update( $table, $set, $where, $fname );
2986                         } else {
2987                                 $ok = true;
2988                         }
2989                         # Now insert any non-conflicting row(s)
2990                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2991                 } catch ( Exception $e ) {
2992                         if ( $useTrx ) {
2993                                 $this->rollback( $fname );
2994                         }
2995                         throw $e;
2996                 }
2997                 if ( $useTrx ) {
2998                         $this->commit( $fname );
2999                 }
3000
3001                 return $ok;
3002         }
3003
3004         /**
3005          * DELETE where the condition is a join.
3006          *
3007          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
3008          * we use sub-selects
3009          *
3010          * For safety, an empty $conds will not delete everything. If you want to
3011          * delete all rows where the join condition matches, set $conds='*'.
3012          *
3013          * DO NOT put the join condition in $conds.
3014          *
3015          * @param string $delTable The table to delete from.
3016          * @param string $joinTable The other table.
3017          * @param string $delVar The variable to join on, in the first table.
3018          * @param string $joinVar The variable to join on, in the second table.
3019          * @param array $conds Condition array of field names mapped to variables,
3020          *   ANDed together in the WHERE clause
3021          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
3022          * @throws DBUnexpectedError
3023          */
3024         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
3025                 $fname = __METHOD__
3026         ) {
3027                 if ( !$conds ) {
3028                         throw new DBUnexpectedError( $this,
3029                                 'DatabaseBase::deleteJoin() called with empty $conds' );
3030                 }
3031
3032                 $delTable = $this->tableName( $delTable );
3033                 $joinTable = $this->tableName( $joinTable );
3034                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
3035                 if ( $conds != '*' ) {
3036                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
3037                 }
3038                 $sql .= ')';
3039
3040                 $this->query( $sql, $fname );
3041         }
3042
3043         /**
3044          * Returns the size of a text field, or -1 for "unlimited"
3045          *
3046          * @param string $table
3047          * @param string $field
3048          * @return int
3049          */
3050         public function textFieldSize( $table, $field ) {
3051                 $table = $this->tableName( $table );
3052                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
3053                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
3054                 $row = $this->fetchObject( $res );
3055
3056                 $m = array();
3057
3058                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
3059                         $size = $m[1];
3060                 } else {
3061                         $size = -1;
3062                 }
3063
3064                 return $size;
3065         }
3066
3067         /**
3068          * A string to insert into queries to show that they're low-priority, like
3069          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
3070          * string and nothing bad should happen.
3071          *
3072          * @return string Returns the text of the low priority option if it is
3073          *   supported, or a blank string otherwise
3074          */
3075         public function lowPriorityOption() {
3076                 return '';
3077         }
3078
3079         /**
3080          * DELETE query wrapper.
3081          *
3082          * @param array $table Table name
3083          * @param string|array $conds Array of conditions. See $conds in DatabaseBase::select()
3084          *   for the format. Use $conds == "*" to delete all rows
3085          * @param string $fname Name of the calling function
3086          * @throws DBUnexpectedError
3087          * @return bool|ResultWrapper
3088          */
3089         public function delete( $table, $conds, $fname = __METHOD__ ) {
3090                 if ( !$conds ) {
3091                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
3092                 }
3093
3094                 $table = $this->tableName( $table );
3095                 $sql = "DELETE FROM $table";
3096
3097                 if ( $conds != '*' ) {
3098                         if ( is_array( $conds ) ) {
3099                                 $conds = $this->makeList( $conds, LIST_AND );
3100                         }
3101                         $sql .= ' WHERE ' . $conds;
3102                 }
3103
3104                 return $this->query( $sql, $fname );
3105         }
3106
3107         /**
3108          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
3109          * into another table.
3110          *
3111          * @param string $destTable The table name to insert into
3112          * @param string|array $srcTable May be either a table name, or an array of table names
3113          *    to include in a join.
3114          *
3115          * @param array $varMap Must be an associative array of the form
3116          *    array( 'dest1' => 'source1', ...). Source items may be literals
3117          *    rather than field names, but strings should be quoted with
3118          *    DatabaseBase::addQuotes()
3119          *
3120          * @param array $conds Condition array. See $conds in DatabaseBase::select() for
3121          *    the details of the format of condition arrays. May be "*" to copy the
3122          *    whole table.
3123          *
3124          * @param string $fname The function name of the caller, from __METHOD__
3125          *
3126          * @param array $insertOptions Options for the INSERT part of the query, see
3127          *    DatabaseBase::insert() for details.
3128          * @param array $selectOptions Options for the SELECT part of the query, see
3129          *    DatabaseBase::select() for details.
3130          *
3131          * @return ResultWrapper
3132          */
3133         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
3134                 $fname = __METHOD__,
3135                 $insertOptions = array(), $selectOptions = array()
3136         ) {
3137                 $destTable = $this->tableName( $destTable );
3138
3139                 if ( !is_array( $insertOptions ) ) {
3140                         $insertOptions = array( $insertOptions );
3141                 }
3142
3143                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3144
3145                 if ( !is_array( $selectOptions ) ) {
3146                         $selectOptions = array( $selectOptions );
3147                 }
3148
3149                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
3150
3151                 if ( is_array( $srcTable ) ) {
3152                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
3153                 } else {
3154                         $srcTable = $this->tableName( $srcTable );
3155                 }
3156
3157                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
3158                         " SELECT $startOpts " . implode( ',', $varMap ) .
3159                         " FROM $srcTable $useIndex ";
3160
3161                 if ( $conds != '*' ) {
3162                         if ( is_array( $conds ) ) {
3163                                 $conds = $this->makeList( $conds, LIST_AND );
3164                         }
3165                         $sql .= " WHERE $conds";
3166                 }
3167
3168                 $sql .= " $tailOpts";
3169
3170                 return $this->query( $sql, $fname );
3171         }
3172
3173         /**
3174          * Construct a LIMIT query with optional offset. This is used for query
3175          * pages. The SQL should be adjusted so that only the first $limit rows
3176          * are returned. If $offset is provided as well, then the first $offset
3177          * rows should be discarded, and the next $limit rows should be returned.
3178          * If the result of the query is not ordered, then the rows to be returned
3179          * are theoretically arbitrary.
3180          *
3181          * $sql is expected to be a SELECT, if that makes a difference.
3182          *
3183          * The version provided by default works in MySQL and SQLite. It will very
3184          * likely need to be overridden for most other DBMSes.
3185          *
3186          * @param string $sql SQL query we will append the limit too
3187          * @param int $limit The SQL limit
3188          * @param int|bool $offset The SQL offset (default false)
3189          * @throws DBUnexpectedError
3190          * @return string
3191          */
3192         public function limitResult( $sql, $limit, $offset = false ) {
3193                 if ( !is_numeric( $limit ) ) {
3194                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
3195                 }
3196
3197                 return "$sql LIMIT "
3198                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3199                         . "{$limit} ";
3200         }
3201
3202         /**
3203          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
3204          * within the UNION construct.
3205          * @return bool
3206          */
3207         public function unionSupportsOrderAndLimit() {
3208                 return true; // True for almost every DB supported
3209         }
3210
3211         /**
3212          * Construct a UNION query
3213          * This is used for providing overload point for other DB abstractions
3214          * not compatible with the MySQL syntax.
3215          * @param array $sqls SQL statements to combine
3216          * @param bool $all Use UNION ALL
3217          * @return string SQL fragment
3218          */
3219         public function unionQueries( $sqls, $all ) {
3220                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3221
3222                 return '(' . implode( $glue, $sqls ) . ')';
3223         }
3224
3225         /**
3226          * Returns an SQL expression for a simple conditional. This doesn't need
3227          * to be overridden unless CASE isn't supported in your DBMS.
3228          *
3229          * @param string|array $cond SQL expression which will result in a boolean value
3230          * @param string $trueVal SQL expression to return if true
3231          * @param string $falseVal SQL expression to return if false
3232          * @return string SQL fragment
3233          */
3234         public function conditional( $cond, $trueVal, $falseVal ) {
3235                 if ( is_array( $cond ) ) {
3236                         $cond = $this->makeList( $cond, LIST_AND );
3237                 }
3238
3239                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3240         }
3241
3242         /**
3243          * Returns a comand for str_replace function in SQL query.
3244          * Uses REPLACE() in MySQL
3245          *
3246          * @param string $orig Column to modify
3247          * @param string $old Column to seek
3248          * @param string $new Column to replace with
3249          *
3250          * @return string
3251          */
3252         public function strreplace( $orig, $old, $new ) {
3253                 return "REPLACE({$orig}, {$old}, {$new})";
3254         }
3255
3256         /**
3257          * Determines how long the server has been up
3258          * STUB
3259          *
3260          * @return int
3261          */
3262         public function getServerUptime() {
3263                 return 0;
3264         }
3265
3266         /**
3267          * Determines if the last failure was due to a deadlock
3268          * STUB
3269          *
3270          * @return bool
3271          */
3272         public function wasDeadlock() {
3273                 return false;
3274         }
3275
3276         /**
3277          * Determines if the last failure was due to a lock timeout
3278          * STUB
3279          *
3280          * @return bool
3281          */
3282         public function wasLockTimeout() {
3283                 return false;
3284         }
3285
3286         /**
3287          * Determines if the last query error was something that should be dealt
3288          * with by pinging the connection and reissuing the query.
3289          * STUB
3290          *
3291          * @return bool
3292          */
3293         public function wasErrorReissuable() {
3294                 return false;
3295         }
3296
3297         /**
3298          * Determines if the last failure was due to the database being read-only.
3299          * STUB
3300          *
3301          * @return bool
3302          */
3303         public function wasReadOnlyError() {
3304                 return false;
3305         }
3306
3307         /**
3308          * Perform a deadlock-prone transaction.
3309          *
3310          * This function invokes a callback function to perform a set of write
3311          * queries. If a deadlock occurs during the processing, the transaction
3312          * will be rolled back and the callback function will be called again.
3313          *
3314          * Usage:
3315          *   $dbw->deadlockLoop( callback, ... );
3316          *
3317          * Extra arguments are passed through to the specified callback function.
3318          *
3319          * Returns whatever the callback function returned on its successful,
3320          * iteration, or false on error, for example if the retry limit was
3321          * reached.
3322          *
3323          * @return bool
3324          */
3325         public function deadlockLoop() {
3326                 $this->begin( __METHOD__ );
3327                 $args = func_get_args();
3328                 $function = array_shift( $args );
3329                 $oldIgnore = $this->ignoreErrors( true );
3330                 $tries = self::DEADLOCK_TRIES;
3331
3332                 if ( is_array( $function ) ) {
3333                         $fname = $function[0];
3334                 } else {
3335                         $fname = $function;
3336                 }
3337
3338                 do {
3339                         $retVal = call_user_func_array( $function, $args );
3340                         $error = $this->lastError();
3341                         $errno = $this->lastErrno();
3342                         $sql = $this->lastQuery();
3343
3344                         if ( $errno ) {
3345                                 if ( $this->wasDeadlock() ) {
3346                                         # Retry
3347                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3348                                 } else {
3349                                         $this->reportQueryError( $error, $errno, $sql, $fname );
3350                                 }
3351                         }
3352                 } while ( $this->wasDeadlock() && --$tries > 0 );
3353
3354                 $this->ignoreErrors( $oldIgnore );
3355
3356                 if ( $tries <= 0 ) {
3357                         $this->rollback( __METHOD__ );
3358                         $this->reportQueryError( $error, $errno, $sql, $fname );
3359
3360                         return false;
3361                 } else {
3362                         $this->commit( __METHOD__ );
3363
3364                         return $retVal;
3365                 }
3366         }
3367
3368         /**
3369          * Wait for the slave to catch up to a given master position.
3370          *
3371          * @param DBMasterPos $pos
3372          * @param int $timeout The maximum number of seconds to wait for
3373          *   synchronisation
3374          * @return int Zero if the slave was past that position already,
3375          *   greater than zero if we waited for some period of time, less than
3376          *   zero if we timed out.
3377          */
3378         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3379                 # Real waits are implemented in the subclass.
3380                 return 0;
3381         }
3382
3383         /**
3384          * Get the replication position of this slave
3385          *
3386          * @return DBMasterPos|bool False if this is not a slave.
3387          */
3388         public function getSlavePos() {
3389                 # Stub
3390                 return false;
3391         }
3392
3393         /**
3394          * Get the position of this master
3395          *
3396          * @return DBMasterPos|bool False if this is not a master
3397          */
3398         public function getMasterPos() {
3399                 # Stub
3400                 return false;
3401         }
3402
3403         /**
3404          * Run an anonymous function as soon as there is no transaction pending.
3405          * If there is a transaction and it is rolled back, then the callback is cancelled.
3406          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
3407          * Callbacks must commit any transactions that they begin.
3408          *
3409          * This is useful for updates to different systems or when separate transactions are needed.
3410          * For example, one might want to enqueue jobs into a system outside the database, but only
3411          * after the database is updated so that the jobs will see the data when they actually run.
3412          * It can also be used for updates that easily cause deadlocks if locks are held too long.
3413          *
3414          * @param callable $callback
3415          * @since 1.20
3416          */
3417         final public function onTransactionIdle( $callback ) {
3418                 $this->mTrxIdleCallbacks[] = array( $callback, wfGetCaller() );
3419                 if ( !$this->mTrxLevel ) {
3420                         $this->runOnTransactionIdleCallbacks();
3421                 }
3422         }
3423
3424         /**
3425          * Run an anonymous function before the current transaction commits or now if there is none.
3426          * If there is a transaction and it is rolled back, then the callback is cancelled.
3427          * Callbacks must not start nor commit any transactions.
3428          *
3429          * This is useful for updates that easily cause deadlocks if locks are held too long
3430          * but where atomicity is strongly desired for these updates and some related updates.
3431          *
3432          * @param callable $callback
3433          * @since 1.22
3434          */
3435         final public function onTransactionPreCommitOrIdle( $callback ) {
3436                 if ( $this->mTrxLevel ) {
3437                         $this->mTrxPreCommitCallbacks[] = array( $callback, wfGetCaller() );
3438                 } else {
3439                         $this->onTransactionIdle( $callback ); // this will trigger immediately
3440                 }
3441         }
3442
3443         /**
3444          * Actually any "on transaction idle" callbacks.
3445          *
3446          * @since 1.20
3447          */
3448         protected function runOnTransactionIdleCallbacks() {
3449                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
3450
3451                 $e = $ePrior = null; // last exception
3452                 do { // callbacks may add callbacks :)
3453                         $callbacks = $this->mTrxIdleCallbacks;
3454                         $this->mTrxIdleCallbacks = array(); // recursion guard
3455                         foreach ( $callbacks as $callback ) {
3456                                 try {
3457                                         list( $phpCallback ) = $callback;
3458                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
3459                                         call_user_func( $phpCallback );
3460                                         $this->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore automatic begin()
3461                                 } catch ( Exception $e ) {
3462                                         if ( $ePrior ) {
3463                                                 MWExceptionHandler::logException( $ePrior );
3464                                         }
3465                                         $ePrior = $e;
3466                                 }
3467                         }
3468                 } while ( count( $this->mTrxIdleCallbacks ) );
3469
3470                 if ( $e instanceof Exception ) {
3471                         throw $e; // re-throw any last exception
3472                 }
3473         }
3474
3475         /**
3476          * Actually any "on transaction pre-commit" callbacks.
3477          *
3478          * @since 1.22
3479          */
3480         protected function runOnTransactionPreCommitCallbacks() {
3481                 $e = $ePrior = null; // last exception
3482                 do { // callbacks may add callbacks :)
3483                         $callbacks = $this->mTrxPreCommitCallbacks;
3484                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
3485                         foreach ( $callbacks as $callback ) {
3486                                 try {
3487                                         list( $phpCallback ) = $callback;
3488                                         call_user_func( $phpCallback );
3489                                 } catch ( Exception $e ) {
3490                                         if ( $ePrior ) {
3491                                                 MWExceptionHandler::logException( $ePrior );
3492                                         }
3493                                         $ePrior = $e;
3494                                 }
3495                         }
3496                 } while ( count( $this->mTrxPreCommitCallbacks ) );
3497
3498                 if ( $e instanceof Exception ) {
3499                         throw $e; // re-throw any last exception
3500                 }
3501         }
3502
3503         /**
3504          * Begin an atomic section of statements
3505          *
3506          * If a transaction has been started already, just keep track of the given
3507          * section name to make sure the transaction is not committed pre-maturely.
3508          * This function can be used in layers (with sub-sections), so use a stack
3509          * to keep track of the different atomic sections. If there is no transaction,
3510          * start one implicitly.
3511          *
3512          * The goal of this function is to create an atomic section of SQL queries
3513          * without having to start a new transaction if it already exists.
3514          *
3515          * Atomic sections are more strict than transactions. With transactions,
3516          * attempting to begin a new transaction when one is already running results
3517          * in MediaWiki issuing a brief warning and doing an implicit commit. All
3518          * atomic levels *must* be explicitly closed using DatabaseBase::endAtomic(),
3519          * and any database transactions cannot be began or committed until all atomic
3520          * levels are closed. There is no such thing as implicitly opening or closing
3521          * an atomic section.
3522          *
3523          * @since 1.23
3524          * @param string $fname
3525          * @throws DBError
3526          */
3527         final public function startAtomic( $fname = __METHOD__ ) {
3528                 if ( !$this->mTrxLevel ) {
3529                         $this->begin( $fname );
3530                         $this->mTrxAutomatic = true;
3531                         $this->mTrxAutomaticAtomic = true;
3532                 }
3533
3534                 $this->mTrxAtomicLevels->push( $fname );
3535         }
3536
3537         /**
3538          * Ends an atomic section of SQL statements
3539          *
3540          * Ends the next section of atomic SQL statements and commits the transaction
3541          * if necessary.
3542          *
3543          * @since 1.23
3544          * @see DatabaseBase::startAtomic
3545          * @param string $fname
3546          * @throws DBError
3547          */
3548         final public function endAtomic( $fname = __METHOD__ ) {
3549                 if ( !$this->mTrxLevel ) {
3550                         throw new DBUnexpectedError( $this, 'No atomic transaction is open.' );
3551                 }
3552                 if ( $this->mTrxAtomicLevels->isEmpty() ||
3553                         $this->mTrxAtomicLevels->pop() !== $fname
3554                 ) {
3555                         throw new DBUnexpectedError( $this, 'Invalid atomic section ended.' );
3556                 }
3557
3558                 if ( $this->mTrxAtomicLevels->isEmpty() && $this->mTrxAutomaticAtomic ) {
3559                         $this->commit( $fname, 'flush' );
3560                 }
3561         }
3562
3563         /**
3564          * Begin a transaction. If a transaction is already in progress,
3565          * that transaction will be committed before the new transaction is started.
3566          *
3567          * Note that when the DBO_TRX flag is set (which is usually the case for web
3568          * requests, but not for maintenance scripts), any previous database query
3569          * will have started a transaction automatically.
3570          *
3571          * Nesting of transactions is not supported. Attempts to nest transactions
3572          * will cause a warning, unless the current transaction was started
3573          * automatically because of the DBO_TRX flag.
3574          *
3575          * @param string $fname
3576          * @throws DBError
3577          */
3578         final public function begin( $fname = __METHOD__ ) {
3579                 global $wgDebugDBTransactions;
3580
3581                 if ( $this->mTrxLevel ) { // implicit commit
3582                         if ( !$this->mTrxAtomicLevels->isEmpty() ) {
3583                                 // If the current transaction was an automatic atomic one, then we definitely have
3584                                 // a problem. Same if there is any unclosed atomic level.
3585                                 throw new DBUnexpectedError( $this,
3586                                         "Attempted to start explicit transaction when atomic levels are still open."
3587                                 );
3588                         } elseif ( !$this->mTrxAutomatic ) {
3589                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
3590                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
3591                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
3592                                         " performing implicit commit!";
3593                                 wfWarn( $msg );
3594                                 wfLogDBError( $msg,
3595                                         $this->getLogContext( array(
3596                                                 'method' => __METHOD__,
3597                                                 'fname' => $fname,
3598                                         ) )
3599                                 );
3600                         } else {
3601                                 // if the transaction was automatic and has done write operations,
3602                                 // log it if $wgDebugDBTransactions is enabled.
3603                                 if ( $this->mTrxDoneWrites && $wgDebugDBTransactions ) {
3604                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
3605                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
3606                                         );
3607                                 }
3608                         }
3609
3610                         $this->runOnTransactionPreCommitCallbacks();
3611                         $this->doCommit( $fname );
3612                         if ( $this->mTrxDoneWrites ) {
3613                                 Profiler::instance()->getTransactionProfiler()->transactionWritingOut(
3614                                         $this->mServer, $this->mDBname, $this->mTrxShortId );
3615                         }
3616                         $this->runOnTransactionIdleCallbacks();
3617                 }
3618
3619                 # Avoid fatals if close() was called
3620                 if ( !$this->isOpen() ) {
3621                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
3622                 }
3623
3624                 $this->doBegin( $fname );
3625                 $this->mTrxTimestamp = microtime( true );
3626                 $this->mTrxFname = $fname;
3627                 $this->mTrxDoneWrites = false;
3628                 $this->mTrxAutomatic = false;
3629                 $this->mTrxAutomaticAtomic = false;
3630                 $this->mTrxAtomicLevels = new SplStack;
3631                 $this->mTrxIdleCallbacks = array();
3632                 $this->mTrxPreCommitCallbacks = array();
3633                 $this->mTrxShortId = wfRandomString( 12 );
3634         }
3635
3636         /**
3637          * Issues the BEGIN command to the database server.
3638          *
3639          * @see DatabaseBase::begin()
3640          * @param string $fname
3641          */
3642         protected function doBegin( $fname ) {
3643                 $this->query( 'BEGIN', $fname );
3644                 $this->mTrxLevel = 1;
3645         }
3646
3647         /**
3648          * Commits a transaction previously started using begin().
3649          * If no transaction is in progress, a warning is issued.
3650          *
3651          * Nesting of transactions is not supported.
3652          *
3653          * @param string $fname
3654          * @param string $flush Flush flag, set to 'flush' to disable warnings about
3655          *   explicitly committing implicit transactions, or calling commit when no
3656          *   transaction is in progress. This will silently break any ongoing
3657          *   explicit transaction. Only set the flush flag if you are sure that it
3658          *   is safe to ignore these warnings in your context.
3659          * @throws DBUnexpectedError
3660          */
3661         final public function commit( $fname = __METHOD__, $flush = '' ) {
3662                 if ( !$this->mTrxAtomicLevels->isEmpty() ) {
3663                         // There are still atomic sections open. This cannot be ignored
3664                         throw new DBUnexpectedError(
3665                                 $this,
3666                                 "Attempted to commit transaction while atomic sections are still open"
3667                         );
3668                 }
3669
3670                 if ( $flush === 'flush' ) {
3671                         if ( !$this->mTrxLevel ) {
3672                                 return; // nothing to do
3673                         } elseif ( !$this->mTrxAutomatic ) {
3674                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3675                         }
3676                 } else {
3677                         if ( !$this->mTrxLevel ) {
3678                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
3679                                 return; // nothing to do
3680                         } elseif ( $this->mTrxAutomatic ) {
3681                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
3682                         }
3683                 }
3684
3685                 # Avoid fatals if close() was called
3686                 if ( !$this->isOpen() ) {
3687                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
3688                 }
3689
3690                 $this->runOnTransactionPreCommitCallbacks();
3691                 $this->doCommit( $fname );
3692                 if ( $this->mTrxDoneWrites ) {
3693                         Profiler::instance()->getTransactionProfiler()->transactionWritingOut(
3694                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3695                 }
3696                 $this->runOnTransactionIdleCallbacks();
3697         }
3698
3699         /**
3700          * Issues the COMMIT command to the database server.
3701          *
3702          * @see DatabaseBase::commit()
3703          * @param string $fname
3704          */
3705         protected function doCommit( $fname ) {
3706                 if ( $this->mTrxLevel ) {
3707                         $this->query( 'COMMIT', $fname );
3708                         $this->mTrxLevel = 0;
3709                 }
3710         }
3711
3712         /**
3713          * Rollback a transaction previously started using begin().
3714          * If no transaction is in progress, a warning is issued.
3715          *
3716          * No-op on non-transactional databases.
3717          *
3718          * @param string $fname
3719          * @param string $flush Flush flag, set to 'flush' to disable warnings about
3720          *   calling rollback when no transaction is in progress. This will silently
3721          *   break any ongoing explicit transaction. Only set the flush flag if you
3722          *   are sure that it is safe to ignore these warnings in your context.
3723          * @throws DBUnexpectedError
3724          * @since 1.23 Added $flush parameter
3725          */
3726         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3727                 if ( $flush !== 'flush' ) {
3728                         if ( !$this->mTrxLevel ) {
3729                                 wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
3730                                 return; // nothing to do
3731                         } elseif ( $this->mTrxAutomatic ) {
3732                                 wfWarn( "$fname: Explicit rollback of implicit transaction. Something may be out of sync!" );
3733                         }
3734                 } else {
3735                         if ( !$this->mTrxLevel ) {
3736                                 return; // nothing to do
3737                         } elseif ( !$this->mTrxAutomatic ) {
3738                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3739                         }
3740                 }
3741
3742                 # Avoid fatals if close() was called
3743                 if ( !$this->isOpen() ) {
3744                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
3745                 }
3746
3747                 $this->doRollback( $fname );
3748                 $this->mTrxIdleCallbacks = array(); // cancel
3749                 $this->mTrxPreCommitCallbacks = array(); // cancel
3750                 $this->mTrxAtomicLevels = new SplStack;
3751                 if ( $this->mTrxDoneWrites ) {
3752                         Profiler::instance()->getTransactionProfiler()->transactionWritingOut(
3753                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3754                 }
3755         }
3756
3757         /**
3758          * Issues the ROLLBACK command to the database server.
3759          *
3760          * @see DatabaseBase::rollback()
3761          * @param string $fname
3762          */
3763         protected function doRollback( $fname ) {
3764                 if ( $this->mTrxLevel ) {
3765                         $this->query( 'ROLLBACK', $fname, true );
3766                         $this->mTrxLevel = 0;
3767                 }
3768         }
3769
3770         /**
3771          * Creates a new table with structure copied from existing table
3772          * Note that unlike most database abstraction functions, this function does not
3773          * automatically append database prefix, because it works at a lower
3774          * abstraction level.
3775          * The table names passed to this function shall not be quoted (this
3776          * function calls addIdentifierQuotes when needed).
3777          *
3778          * @param string $oldName Name of table whose structure should be copied
3779          * @param string $newName Name of table to be created
3780          * @param bool $temporary Whether the new table should be temporary
3781          * @param string $fname Calling function name
3782          * @throws MWException
3783          * @return bool True if operation was successful
3784          */
3785         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3786                 $fname = __METHOD__
3787         ) {
3788                 throw new MWException(
3789                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3790         }
3791
3792         /**
3793          * List all tables on the database
3794          *
3795          * @param string $prefix Only show tables with this prefix, e.g. mw_
3796          * @param string $fname Calling function name
3797          * @throws MWException
3798          */
3799         function listTables( $prefix = null, $fname = __METHOD__ ) {
3800                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3801         }
3802
3803         /**
3804          * Reset the views process cache set by listViews()
3805          * @since 1.22
3806          */
3807         final public function clearViewsCache() {
3808                 $this->allViews = null;
3809         }
3810
3811         /**
3812          * Lists all the VIEWs in the database
3813          *
3814          * For caching purposes the list of all views should be stored in
3815          * $this->allViews. The process cache can be cleared with clearViewsCache()
3816          *
3817          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3818          * @param string $fname Name of calling function
3819          * @throws MWException
3820          * @since 1.22
3821          */
3822         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3823                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
3824         }
3825
3826         /**
3827          * Differentiates between a TABLE and a VIEW
3828          *
3829          * @param string $name Name of the database-structure to test.
3830          * @throws MWException
3831          * @since 1.22
3832          */
3833         public function isView( $name ) {
3834                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
3835         }
3836
3837         /**
3838          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3839          * to the format used for inserting into timestamp fields in this DBMS.
3840          *
3841          * The result is unquoted, and needs to be passed through addQuotes()
3842          * before it can be included in raw SQL.
3843          *
3844          * @param string|int $ts
3845          *
3846          * @return string
3847          */
3848         public function timestamp( $ts = 0 ) {
3849                 return wfTimestamp( TS_MW, $ts );
3850         }
3851
3852         /**
3853          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3854          * to the format used for inserting into timestamp fields in this DBMS. If
3855          * NULL is input, it is passed through, allowing NULL values to be inserted
3856          * into timestamp fields.
3857          *
3858          * The result is unquoted, and needs to be passed through addQuotes()
3859          * before it can be included in raw SQL.
3860          *
3861          * @param string|int $ts
3862          *
3863          * @return string
3864          */
3865         public function timestampOrNull( $ts = null ) {
3866                 if ( is_null( $ts ) ) {
3867                         return null;
3868                 } else {
3869                         return $this->timestamp( $ts );
3870                 }
3871         }
3872
3873         /**
3874          * Take the result from a query, and wrap it in a ResultWrapper if
3875          * necessary. Boolean values are passed through as is, to indicate success
3876          * of write queries or failure.
3877          *
3878          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3879          * resource, and it was necessary to call this function to convert it to
3880          * a wrapper. Nowadays, raw database objects are never exposed to external
3881          * callers, so this is unnecessary in external code. For compatibility with
3882          * old code, ResultWrapper objects are passed through unaltered.
3883          *
3884          * @param bool|ResultWrapper|resource $result
3885          * @return bool|ResultWrapper
3886          */
3887         public function resultObject( $result ) {
3888                 if ( empty( $result ) ) {
3889                         return false;
3890                 } elseif ( $result instanceof ResultWrapper ) {
3891                         return $result;
3892                 } elseif ( $result === true ) {
3893                         // Successful write query
3894                         return $result;
3895                 } else {
3896                         return new ResultWrapper( $this, $result );
3897                 }
3898         }
3899
3900         /**
3901          * Ping the server and try to reconnect if it there is no connection
3902          *
3903          * @return bool Success or failure
3904          */
3905         public function ping() {
3906                 # Stub. Not essential to override.
3907                 return true;
3908         }
3909
3910         /**
3911          * Get slave lag. Currently supported only by MySQL.
3912          *
3913          * Note that this function will generate a fatal error on many
3914          * installations. Most callers should use LoadBalancer::safeGetLag()
3915          * instead.
3916          *
3917          * @return int Database replication lag in seconds
3918          */
3919         public function getLag() {
3920                 return 0;
3921         }
3922
3923         /**
3924          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3925          *
3926          * @return int
3927          */
3928         function maxListLen() {
3929                 return 0;
3930         }
3931
3932         /**
3933          * Some DBMSs have a special format for inserting into blob fields, they
3934          * don't allow simple quoted strings to be inserted. To insert into such
3935          * a field, pass the data through this function before passing it to
3936          * DatabaseBase::insert().
3937          *
3938          * @param string $b
3939          * @return string
3940          */
3941         public function encodeBlob( $b ) {
3942                 return $b;
3943         }
3944
3945         /**
3946          * Some DBMSs return a special placeholder object representing blob fields
3947          * in result objects. Pass the object through this function to return the
3948          * original string.
3949          *
3950          * @param string $b
3951          * @return string
3952          */
3953         public function decodeBlob( $b ) {
3954                 return $b;
3955         }
3956
3957         /**
3958          * Override database's default behavior. $options include:
3959          *     'connTimeout' : Set the connection timeout value in seconds.
3960          *                     May be useful for very long batch queries such as
3961          *                     full-wiki dumps, where a single query reads out over
3962          *                     hours or days.
3963          *
3964          * @param array $options
3965          * @return void
3966          */
3967         public function setSessionOptions( array $options ) {
3968         }
3969
3970         /**
3971          * Read and execute SQL commands from a file.
3972          *
3973          * Returns true on success, error string or exception on failure (depending
3974          * on object's error ignore settings).
3975          *
3976          * @param string $filename File name to open
3977          * @param bool|callable $lineCallback Optional function called before reading each line
3978          * @param bool|callable $resultCallback Optional function called for each MySQL result
3979          * @param bool|string $fname Calling function name or false if name should be
3980          *   generated dynamically using $filename
3981          * @param bool|callable $inputCallback Optional function called for each
3982          *   complete line sent
3983          * @throws Exception|MWException
3984          * @return bool|string
3985          */
3986         public function sourceFile(
3987                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3988         ) {
3989                 wfSuppressWarnings();
3990                 $fp = fopen( $filename, 'r' );
3991                 wfRestoreWarnings();
3992
3993                 if ( false === $fp ) {
3994                         throw new MWException( "Could not open \"{$filename}\".\n" );
3995                 }
3996
3997                 if ( !$fname ) {
3998                         $fname = __METHOD__ . "( $filename )";
3999                 }
4000
4001                 try {
4002                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4003                 } catch ( Exception $e ) {
4004                         fclose( $fp );
4005                         throw $e;
4006                 }
4007
4008                 fclose( $fp );
4009
4010                 return $error;
4011         }
4012
4013         /**
4014          * Get the full path of a patch file. Originally based on archive()
4015          * from updaters.inc. Keep in mind this always returns a patch, as
4016          * it fails back to MySQL if no DB-specific patch can be found
4017          *
4018          * @param string $patch The name of the patch, like patch-something.sql
4019          * @return string Full path to patch file
4020          */
4021         public function patchPath( $patch ) {
4022                 global $IP;
4023
4024                 $dbType = $this->getType();
4025                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
4026                         return "$IP/maintenance/$dbType/archives/$patch";
4027                 } else {
4028                         return "$IP/maintenance/archives/$patch";
4029                 }
4030         }
4031
4032         /**
4033          * Set variables to be used in sourceFile/sourceStream, in preference to the
4034          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
4035          * all. If it's set to false, $GLOBALS will be used.
4036          *
4037          * @param bool|array $vars Mapping variable name to value.
4038          */
4039         public function setSchemaVars( $vars ) {
4040                 $this->mSchemaVars = $vars;
4041         }
4042
4043         /**
4044          * Read and execute commands from an open file handle.
4045          *
4046          * Returns true on success, error string or exception on failure (depending
4047          * on object's error ignore settings).
4048          *
4049          * @param resource $fp File handle
4050          * @param bool|callable $lineCallback Optional function called before reading each query
4051          * @param bool|callable $resultCallback Optional function called for each MySQL result
4052          * @param string $fname Calling function name
4053          * @param bool|callable $inputCallback Optional function called for each complete query sent
4054          * @return bool|string
4055          */
4056         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
4057                 $fname = __METHOD__, $inputCallback = false
4058         ) {
4059                 $cmd = '';
4060
4061                 while ( !feof( $fp ) ) {
4062                         if ( $lineCallback ) {
4063                                 call_user_func( $lineCallback );
4064                         }
4065
4066                         $line = trim( fgets( $fp ) );
4067
4068                         if ( $line == '' ) {
4069                                 continue;
4070                         }
4071
4072                         if ( '-' == $line[0] && '-' == $line[1] ) {
4073                                 continue;
4074                         }
4075
4076                         if ( $cmd != '' ) {
4077                                 $cmd .= ' ';
4078                         }
4079
4080                         $done = $this->streamStatementEnd( $cmd, $line );
4081
4082                         $cmd .= "$line\n";
4083
4084                         if ( $done || feof( $fp ) ) {
4085                                 $cmd = $this->replaceVars( $cmd );
4086
4087                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
4088                                         $res = $this->query( $cmd, $fname );
4089
4090                                         if ( $resultCallback ) {
4091                                                 call_user_func( $resultCallback, $res, $this );
4092                                         }
4093
4094                                         if ( false === $res ) {
4095                                                 $err = $this->lastError();
4096
4097                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4098                                         }
4099                                 }
4100                                 $cmd = '';
4101                         }
4102                 }
4103
4104                 return true;
4105         }
4106
4107         /**
4108          * Called by sourceStream() to check if we've reached a statement end
4109          *
4110          * @param string $sql SQL assembled so far
4111          * @param string $newLine New line about to be added to $sql
4112          * @return bool Whether $newLine contains end of the statement
4113          */
4114         public function streamStatementEnd( &$sql, &$newLine ) {
4115                 if ( $this->delimiter ) {
4116                         $prev = $newLine;
4117                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4118                         if ( $newLine != $prev ) {
4119                                 return true;
4120                         }
4121                 }
4122
4123                 return false;
4124         }
4125
4126         /**
4127          * Database independent variable replacement. Replaces a set of variables
4128          * in an SQL statement with their contents as given by $this->getSchemaVars().
4129          *
4130          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4131          *
4132          * - '{$var}' should be used for text and is passed through the database's
4133          *   addQuotes method.
4134          * - `{$var}` should be used for identifiers (e.g. table and database names).
4135          *   It is passed through the database's addIdentifierQuotes method which
4136          *   can be overridden if the database uses something other than backticks.
4137          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4138          *   database's tableName method.
4139          * - / *i* / passes the name that follows through the database's indexName method.
4140          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4141          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4142          *
4143          * @param string $ins SQL statement to replace variables in
4144          * @return string The new SQL statement with variables replaced
4145          */
4146         protected function replaceVars( $ins ) {
4147                 $that = $this;
4148                 $vars = $this->getSchemaVars();
4149                 return preg_replace_callback(
4150                         '!
4151                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4152                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4153                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4154                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4155                         !x',
4156                         function ( $m ) use ( $that, $vars ) {
4157                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4158                                 // check for both nonexistent keys *and* the empty string.
4159                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4160                                         if ( $m[1] === 'i' ) {
4161                                                 return $that->indexName( $m[2] );
4162                                         } else {
4163                                                 return $that->tableName( $m[2] );
4164                                         }
4165                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4166                                         return $that->addQuotes( $vars[$m[3]] );
4167                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4168                                         return $that->addIdentifierQuotes( $vars[$m[4]] );
4169                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4170                                         return $vars[$m[5]];
4171                                 } else {
4172                                         return $m[0];
4173                                 }
4174                         },
4175                         $ins
4176                 );
4177         }
4178
4179         /**
4180          * Get schema variables. If none have been set via setSchemaVars(), then
4181          * use some defaults from the current object.
4182          *
4183          * @return array
4184          */
4185         protected function getSchemaVars() {
4186                 if ( $this->mSchemaVars ) {
4187                         return $this->mSchemaVars;
4188                 } else {
4189                         return $this->getDefaultSchemaVars();
4190                 }
4191         }
4192
4193         /**
4194          * Get schema variables to use if none have been set via setSchemaVars().
4195          *
4196          * Override this in derived classes to provide variables for tables.sql
4197          * and SQL patch files.
4198          *
4199          * @return array
4200          */
4201         protected function getDefaultSchemaVars() {
4202                 return array();
4203         }
4204
4205         /**
4206          * Check to see if a named lock is available. This is non-blocking.
4207          *
4208          * @param string $lockName Name of lock to poll
4209          * @param string $method Name of method calling us
4210          * @return bool
4211          * @since 1.20
4212          */
4213         public function lockIsFree( $lockName, $method ) {
4214                 return true;
4215         }
4216
4217         /**
4218          * Acquire a named lock
4219          *
4220          * Abstracted from Filestore::lock() so child classes can implement for
4221          * their own needs.
4222          *
4223          * @param string $lockName Name of lock to aquire
4224          * @param string $method Name of method calling us
4225          * @param int $timeout
4226          * @return bool
4227          */
4228         public function lock( $lockName, $method, $timeout = 5 ) {
4229                 return true;
4230         }
4231
4232         /**
4233          * Release a lock.
4234          *
4235          * @param string $lockName Name of lock to release
4236          * @param string $method Name of method calling us
4237          *
4238          * @return int Returns 1 if the lock was released, 0 if the lock was not established
4239          * by this thread (in which case the lock is not released), and NULL if the named
4240          * lock did not exist
4241          */
4242         public function unlock( $lockName, $method ) {
4243                 return true;
4244         }
4245
4246         /**
4247          * Lock specific tables
4248          *
4249          * @param array $read Array of tables to lock for read access
4250          * @param array $write Array of tables to lock for write access
4251          * @param string $method Name of caller
4252          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
4253          * @return bool
4254          */
4255         public function lockTables( $read, $write, $method, $lowPriority = true ) {
4256                 return true;
4257         }
4258
4259         /**
4260          * Unlock specific tables
4261          *
4262          * @param string $method The caller
4263          * @return bool
4264          */
4265         public function unlockTables( $method ) {
4266                 return true;
4267         }
4268
4269         /**
4270          * Delete a table
4271          * @param string $tableName
4272          * @param string $fName
4273          * @return bool|ResultWrapper
4274          * @since 1.18
4275          */
4276         public function dropTable( $tableName, $fName = __METHOD__ ) {
4277                 if ( !$this->tableExists( $tableName, $fName ) ) {
4278                         return false;
4279                 }
4280                 $sql = "DROP TABLE " . $this->tableName( $tableName );
4281                 if ( $this->cascadingDeletes() ) {
4282                         $sql .= " CASCADE";
4283                 }
4284
4285                 return $this->query( $sql, $fName );
4286         }
4287
4288         /**
4289          * Get search engine class. All subclasses of this need to implement this
4290          * if they wish to use searching.
4291          *
4292          * @return string
4293          */
4294         public function getSearchEngine() {
4295                 return 'SearchEngineDummy';
4296         }
4297
4298         /**
4299          * Find out when 'infinity' is. Most DBMSes support this. This is a special
4300          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
4301          * because "i" sorts after all numbers.
4302          *
4303          * @return string
4304          */
4305         public function getInfinity() {
4306                 return 'infinity';
4307         }
4308
4309         /**
4310          * Encode an expiry time into the DBMS dependent format
4311          *
4312          * @param string $expiry Timestamp for expiry, or the 'infinity' string
4313          * @return string
4314          */
4315         public function encodeExpiry( $expiry ) {
4316                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4317                         ? $this->getInfinity()
4318                         : $this->timestamp( $expiry );
4319         }
4320
4321         /**
4322          * Decode an expiry time into a DBMS independent format
4323          *
4324          * @param string $expiry DB timestamp field value for expiry
4325          * @param int $format TS_* constant, defaults to TS_MW
4326          * @return string
4327          */
4328         public function decodeExpiry( $expiry, $format = TS_MW ) {
4329                 return ( $expiry == '' || $expiry == $this->getInfinity() )
4330                         ? 'infinity'
4331                         : wfTimestamp( $format, $expiry );
4332         }
4333
4334         /**
4335          * Allow or deny "big selects" for this session only. This is done by setting
4336          * the sql_big_selects session variable.
4337          *
4338          * This is a MySQL-specific feature.
4339          *
4340          * @param bool|string $value True for allow, false for deny, or "default" to
4341          *   restore the initial value
4342          */
4343         public function setBigSelects( $value = true ) {
4344                 // no-op
4345         }
4346
4347         /**
4348          * @since 1.19
4349          * @return string
4350          */
4351         public function __toString() {
4352                 return (string)$this->mConn;
4353         }
4354
4355         /**
4356          * Run a few simple sanity checks
4357          */
4358         public function __destruct() {
4359                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
4360                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
4361                 }
4362                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
4363                         $callers = array();
4364                         foreach ( $this->mTrxIdleCallbacks as $callbackInfo ) {
4365                                 $callers[] = $callbackInfo[1];
4366                         }
4367                         $callers = implode( ', ', $callers );
4368                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
4369                 }
4370         }
4371 }