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