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          * Track the seconds spent in write queries for the current transaction
 146          *
 147          * @var float
 148          */
 149         private $mTrxWriteDuration = 0.0;
 150
 151         /**
 152          * @since 1.21
 153          * @var resource File handle for upgrade
 154          */
 155         protected $fileHandle = null;
 156
 157         /**
 158          * @since 1.22
 159          * @var string[] Process cache of VIEWs names in the database
 160          */
 161         protected $allViews = null;
 162
 163         /** @var TransactionProfiler */
 164         protected $trxProfiler;
 165
 166         /**
 167          * A string describing the current software version, and possibly
 168          * other details in a user-friendly way. Will be listed on Special:Version, etc.
 169          * Use getServerVersion() to get machine-friendly information.
 170          *
 171          * @return string Version information from the database server
 172          */
 173         public function getServerInfo() {
 174                 return $this->getServerVersion();
 175         }
 176
 177         /**
 178          * @return string Command delimiter used by this database engine
 179          */
 180         public function getDelimiter() {
 181                 return $this->delimiter;
 182         }
 183
 184         /**
 185          * Boolean, controls output of large amounts of debug information.
 186          * @param bool|null $debug
 187          *   - true to enable debugging
 188          *   - false to disable debugging
 189          *   - omitted or null to do nothing
 190          *
 191          * @return bool|null Previous value of the flag
 192          */
 193         public function debug( $debug = null ) {
 194                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 195         }
 196
 197         /**
 198          * Turns buffering of SQL result sets on (true) or off (false). Default is
 199          * "on".
 200          *
 201          * Unbuffered queries are very troublesome in MySQL:
 202          *
 203          *   - If another query is executed while the first query is being read
 204          *     out, the first query is killed. This means you can't call normal
 205          *     MediaWiki functions while you are reading an unbuffered query result
 206          *     from a normal wfGetDB() connection.
 207          *
 208          *   - Unbuffered queries cause the MySQL server to use large amounts of
 209          *     memory and to hold broad locks which block other queries.
 210          *
 211          * If you want to limit client-side memory, it's almost always better to
 212          * split up queries into batches using a LIMIT clause than to switch off
 213          * buffering.
 214          *
 215          * @param null|bool $buffer
 216          * @return null|bool The previous value of the flag
 217          */
 218         public function bufferResults( $buffer = null ) {
 219                 if ( is_null( $buffer ) ) {
 220                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 221                 } else {
 222                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 223                 }
 224         }
 225
 226         /**
 227          * Turns on (false) or off (true) the automatic generation and sending
 228          * of a "we're sorry, but there has been a database error" page on
 229          * database errors. Default is on (false). When turned off, the
 230          * code should use lastErrno() and lastError() to handle the
 231          * situation as appropriate.
 232          *
 233          * Do not use this function outside of the Database classes.
 234          *
 235          * @param null|bool $ignoreErrors
 236          * @return bool The previous value of the flag.
 237          */
 238         public function ignoreErrors( $ignoreErrors = null ) {
 239                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 240         }
 241
 242         /**
 243          * Gets the current transaction level.
 244          *
 245          * Historically, transactions were allowed to be "nested". This is no
 246          * longer supported, so this function really only returns a boolean.
 247          *
 248          * @return int The previous value
 249          */
 250         public function trxLevel() {
 251                 return $this->mTrxLevel;
 252         }
 253
 254         /**
 255          * Get the UNIX timestamp of the time that the transaction was established
 256          *
 257          * This can be used to reason about the staleness of SELECT data
 258          * in REPEATABLE-READ transaction isolation level.
 259          *
 260          * @return float|null Returns null if there is not active transaction
 261          * @since 1.25
 262          */
 263         public function trxTimestamp() {
 264                 return $this->mTrxLevel ? $this->mTrxTimestamp : null;
 265         }
 266
 267         /**
 268          * Get/set the number of errors logged. Only useful when errors are ignored
 269          * @param int $count The count to set, or omitted to leave it unchanged.
 270          * @return int The error count
 271          */
 272         public function errorCount( $count = null ) {
 273                 return wfSetVar( $this->mErrorCount, $count );
 274         }
 275
 276         /**
 277          * Get/set the table prefix.
 278          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 279          * @return string The previous table prefix.
 280          */
 281         public function tablePrefix( $prefix = null ) {
 282                 return wfSetVar( $this->mTablePrefix, $prefix );
 283         }
 284
 285         /**
 286          * Get/set the db schema.
 287          * @param string $schema The database schema to set, or omitted to leave it unchanged.
 288          * @return string The previous db schema.
 289          */
 290         public function dbSchema( $schema = null ) {
 291                 return wfSetVar( $this->mSchema, $schema );
 292         }
 293
 294         /**
 295          * Set the filehandle to copy write statements to.
 296          *
 297          * @param resource $fh File handle
 298          */
 299         public function setFileHandle( $fh ) {
 300                 $this->fileHandle = $fh;
 301         }
 302
 303         /**
 304          * Get properties passed down from the server info array of the load
 305          * balancer.
 306          *
 307          * @param string $name The entry of the info array to get, or null to get the
 308          *   whole array
 309          *
 310          * @return array|mixed|null
 311          */
 312         public function getLBInfo( $name = null ) {
 313                 if ( is_null( $name ) ) {
 314                         return $this->mLBInfo;
 315                 } else {
 316                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 317                                 return $this->mLBInfo[$name];
 318                         } else {
 319                                 return null;
 320                         }
 321                 }
 322         }
 323
 324         /**
 325          * Set the LB info array, or a member of it. If called with one parameter,
 326          * the LB info array is set to that parameter. If it is called with two
 327          * parameters, the member with the given name is set to the given value.
 328          *
 329          * @param string $name
 330          * @param array $value
 331          */
 332         public function setLBInfo( $name, $value = null ) {
 333                 if ( is_null( $value ) ) {
 334                         $this->mLBInfo = $name;
 335                 } else {
 336                         $this->mLBInfo[$name] = $value;
 337                 }
 338         }
 339
 340         /**
 341          * Set lag time in seconds for a fake slave
 342          *
 343          * @param mixed $lag Valid values for this parameter are determined by the
 344          *   subclass, but should be a PHP scalar or array that would be sensible
 345          *   as part of $wgLBFactoryConf.
 346          */
 347         public function setFakeSlaveLag( $lag ) {
 348         }
 349
 350         /**
 351          * Make this connection a fake master
 352          *
 353          * @param bool $enabled
 354          */
 355         public function setFakeMaster( $enabled = true ) {
 356         }
 357
 358         /**
 359          * @return TransactionProfiler
 360          */
 361         protected function getTransactionProfiler() {
 362                 return $this->trxProfiler
 363                         ? $this->trxProfiler
 364                         : Profiler::instance()->getTransactionProfiler();
 365         }
 366
 367         /**
 368          * Returns true if this database supports (and uses) cascading deletes
 369          *
 370          * @return bool
 371          */
 372         public function cascadingDeletes() {
 373                 return false;
 374         }
 375
 376         /**
 377          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 378          *
 379          * @return bool
 380          */
 381         public function cleanupTriggers() {
 382                 return false;
 383         }
 384
 385         /**
 386          * Returns true if this database is strict about what can be put into an IP field.
 387          * Specifically, it uses a NULL value instead of an empty string.
 388          *
 389          * @return bool
 390          */
 391         public function strictIPs() {
 392                 return false;
 393         }
 394
 395         /**
 396          * Returns true if this database uses timestamps rather than integers
 397          *
 398          * @return bool
 399          */
 400         public function realTimestamps() {
 401                 return false;
 402         }
 403
 404         /**
 405          * Returns true if this database does an implicit sort when doing GROUP BY
 406          *
 407          * @return bool
 408          */
 409         public function implicitGroupby() {
 410                 return true;
 411         }
 412
 413         /**
 414          * Returns true if this database does an implicit order by when the column has an index
 415          * For example: SELECT page_title FROM page LIMIT 1
 416          *
 417          * @return bool
 418          */
 419         public function implicitOrderby() {
 420                 return true;
 421         }
 422
 423         /**
 424          * Returns true if this database can do a native search on IP columns
 425          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 426          *
 427          * @return bool
 428          */
 429         public function searchableIPs() {
 430                 return false;
 431         }
 432
 433         /**
 434          * Returns true if this database can use functional indexes
 435          *
 436          * @return bool
 437          */
 438         public function functionalIndexes() {
 439                 return false;
 440         }
 441
 442         /**
 443          * Return the last query that went through DatabaseBase::query()
 444          * @return string
 445          */
 446         public function lastQuery() {
 447                 return $this->mLastQuery;
 448         }
 449
 450         /**
 451          * Returns true if the connection may have been used for write queries.
 452          * Should return true if unsure.
 453          *
 454          * @return bool
 455          */
 456         public function doneWrites() {
 457                 return (bool)$this->mDoneWrites;
 458         }
 459
 460         /**
 461          * Returns the last time the connection may have been used for write queries.
 462          * Should return a timestamp if unsure.
 463          *
 464          * @return int|float UNIX timestamp or false
 465          * @since 1.24
 466          */
 467         public function lastDoneWrites() {
 468                 return $this->mDoneWrites ?: false;
 469         }
 470
 471         /**
 472          * Returns true if there is a transaction open with possible write
 473          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 474          *
 475          * @return bool
 476          */
 477         public function writesOrCallbacksPending() {
 478                 return $this->mTrxLevel && (
 479                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 480                 );
 481         }
 482
 483         /**
 484          * Get the time spend running write queries for this
 485          *
 486          * High times could be due to scanning, updates, locking, and such
 487          *
 488          * @return float|bool Returns false if not transaction is active
 489          * @since 1.26
 490          */
 491         public function pendingWriteQueryDuration() {
 492                 return $this->mTrxLevel ? $this->mTrxWriteDuration : false;
 493         }
 494
 495         /**
 496          * Is a connection to the database open?
 497          * @return bool
 498          */
 499         public function isOpen() {
 500                 return $this->mOpened;
 501         }
 502
 503         /**
 504          * Set a flag for this connection
 505          *
 506          * @param int $flag DBO_* constants from Defines.php:
 507          *   - DBO_DEBUG: output some debug info (same as debug())
 508          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 509          *   - DBO_TRX: automatically start transactions
 510          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 511          *       and removes it in command line mode
 512          *   - DBO_PERSISTENT: use persistant database connection
 513          */
 514         public function setFlag( $flag ) {
 515                 global $wgDebugDBTransactions;
 516                 $this->mFlags |= $flag;
 517                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 518                         wfDebug( "Implicit transactions are now enabled.\n" );
 519                 }
 520         }
 521
 522         /**
 523          * Clear a flag for this connection
 524          *
 525          * @param int $flag DBO_* constants from Defines.php:
 526          *   - DBO_DEBUG: output some debug info (same as debug())
 527          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 528          *   - DBO_TRX: automatically start transactions
 529          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 530          *       and removes it in command line mode
 531          *   - DBO_PERSISTENT: use persistant database connection
 532          */
 533         public function clearFlag( $flag ) {
 534                 global $wgDebugDBTransactions;
 535                 $this->mFlags &= ~$flag;
 536                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 537                         wfDebug( "Implicit transactions are now disabled.\n" );
 538                 }
 539         }
 540
 541         /**
 542          * Returns a boolean whether the flag $flag is set for this connection
 543          *
 544          * @param int $flag DBO_* constants from Defines.php:
 545          *   - DBO_DEBUG: output some debug info (same as debug())
 546          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 547          *   - DBO_TRX: automatically start transactions
 548          *   - DBO_PERSISTENT: use persistant database connection
 549          * @return bool
 550          */
 551         public function getFlag( $flag ) {
 552                 return !!( $this->mFlags & $flag );
 553         }
 554
 555         /**
 556          * General read-only accessor
 557          *
 558          * @param string $name
 559          * @return string
 560          */
 561         public function getProperty( $name ) {
 562                 return $this->$name;
 563         }
 564
 565         /**
 566          * @return string
 567          */
 568         public function getWikiID() {
 569                 if ( $this->mTablePrefix ) {
 570                         return "{$this->mDBname}-{$this->mTablePrefix}";
 571                 } else {
 572                         return $this->mDBname;
 573                 }
 574         }
 575
 576         /**
 577          * Return a path to the DBMS-specific SQL file if it exists,
 578          * otherwise default SQL file
 579          *
 580          * @param string $filename
 581          * @return string
 582          */
 583         private function getSqlFilePath( $filename ) {
 584                 global $IP;
 585                 $dbmsSpecificFilePath = "$IP/maintenance/" . $this->getType() . "/$filename";
 586                 if ( file_exists( $dbmsSpecificFilePath ) ) {
 587                         return $dbmsSpecificFilePath;
 588                 } else {
 589                         return "$IP/maintenance/$filename";
 590                 }
 591         }
 592
 593         /**
 594          * Return a path to the DBMS-specific schema file,
 595          * otherwise default to tables.sql
 596          *
 597          * @return string
 598          */
 599         public function getSchemaPath() {
 600                 return $this->getSqlFilePath( 'tables.sql' );
 601         }
 602
 603         /**
 604          * Return a path to the DBMS-specific update key file,
 605          * otherwise default to update-keys.sql
 606          *
 607          * @return string
 608          */
 609         public function getUpdateKeysPath() {
 610                 return $this->getSqlFilePath( 'update-keys.sql' );
 611         }
 612
 613         /**
 614          * Get the type of the DBMS, as it appears in $wgDBtype.
 615          *
 616          * @return string
 617          */
 618         abstract function getType();
 619
 620         /**
 621          * Open a connection to the database. Usually aborts on failure
 622          *
 623          * @param string $server Database server host
 624          * @param string $user Database user name
 625          * @param string $password Database user password
 626          * @param string $dbName Database name
 627          * @return bool
 628          * @throws DBConnectionError
 629          */
 630         abstract function open( $server, $user, $password, $dbName );
 631
 632         /**
 633          * Fetch the next row from the given result object, in object form.
 634          * Fields can be retrieved with $row->fieldname, with fields acting like
 635          * member variables.
 636          * If no more rows are available, false is returned.
 637          *
 638          * @param ResultWrapper|stdClass $res Object as returned from DatabaseBase::query(), etc.
 639          * @return stdClass|bool
 640          * @throws DBUnexpectedError Thrown if the database returns an error
 641          */
 642         abstract function fetchObject( $res );
 643
 644         /**
 645          * Fetch the next row from the given result object, in associative array
 646          * form. Fields are retrieved with $row['fieldname'].
 647          * If no more rows are available, false is returned.
 648          *
 649          * @param ResultWrapper $res Result object as returned from DatabaseBase::query(), etc.
 650          * @return array|bool
 651          * @throws DBUnexpectedError Thrown if the database returns an error
 652          */
 653         abstract function fetchRow( $res );
 654
 655         /**
 656          * Get the number of rows in a result object
 657          *
 658          * @param mixed $res A SQL result
 659          * @return int
 660          */
 661         abstract function numRows( $res );
 662
 663         /**
 664          * Get the number of fields in a result object
 665          * @see http://www.php.net/mysql_num_fields
 666          *
 667          * @param mixed $res A SQL result
 668          * @return int
 669          */
 670         abstract function numFields( $res );
 671
 672         /**
 673          * Get a field name in a result object
 674          * @see http://www.php.net/mysql_field_name
 675          *
 676          * @param mixed $res A SQL result
 677          * @param int $n
 678          * @return string
 679          */
 680         abstract function fieldName( $res, $n );
 681
 682         /**
 683          * Get the inserted value of an auto-increment row
 684          *
 685          * The value inserted should be fetched from nextSequenceValue()
 686          *
 687          * Example:
 688          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 689          * $dbw->insert( 'page', array( 'page_id' => $id ) );
 690          * $id = $dbw->insertId();
 691          *
 692          * @return int
 693          */
 694         abstract function insertId();
 695
 696         /**
 697          * Change the position of the cursor in a result object
 698          * @see http://www.php.net/mysql_data_seek
 699          *
 700          * @param mixed $res A SQL result
 701          * @param int $row
 702          */
 703         abstract function dataSeek( $res, $row );
 704
 705         /**
 706          * Get the last error number
 707          * @see http://www.php.net/mysql_errno
 708          *
 709          * @return int
 710          */
 711         abstract function lastErrno();
 712
 713         /**
 714          * Get a description of the last error
 715          * @see http://www.php.net/mysql_error
 716          *
 717          * @return string
 718          */
 719         abstract function lastError();
 720
 721         /**
 722          * mysql_fetch_field() wrapper
 723          * Returns false if the field doesn't exist
 724          *
 725          * @param string $table Table name
 726          * @param string $field Field name
 727          *
 728          * @return Field
 729          */
 730         abstract function fieldInfo( $table, $field );
 731
 732         /**
 733          * Get information about an index into an object
 734          * @param string $table Table name
 735          * @param string $index Index name
 736          * @param string $fname Calling function name
 737          * @return mixed Database-specific index description class or false if the index does not exist
 738          */
 739         abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 740
 741         /**
 742          * Get the number of rows affected by the last write query
 743          * @see http://www.php.net/mysql_affected_rows
 744          *
 745          * @return int
 746          */
 747         abstract function affectedRows();
 748
 749         /**
 750          * Wrapper for addslashes()
 751          *
 752          * @param string $s String to be slashed.
 753          * @return string Slashed string.
 754          */
 755         abstract function strencode( $s );
 756
 757         /**
 758          * Returns a wikitext link to the DB's website, e.g.,
 759          *   return "[http://www.mysql.com/ MySQL]";
 760          * Should at least contain plain text, if for some reason
 761          * your database has no website.
 762          *
 763          * @return string Wikitext of a link to the server software's web site
 764          */
 765         abstract function getSoftwareLink();
 766
 767         /**
 768          * A string describing the current software version, like from
 769          * mysql_get_server_info().
 770          *
 771          * @return string Version information from the database server.
 772          */
 773         abstract function getServerVersion();
 774
 775         /**
 776          * Constructor.
 777          *
 778          * FIXME: It is possible to construct a Database object with no associated
 779          * connection object, by specifying no parameters to __construct(). This
 780          * feature is deprecated and should be removed.
 781          *
 782          * DatabaseBase subclasses should not be constructed directly in external
 783          * code. DatabaseBase::factory() should be used instead.
 784          *
 785          * @param array $params Parameters passed from DatabaseBase::factory()
 786          */
 787         function __construct( array $params ) {
 788                 global $wgDBprefix, $wgDBmwschema, $wgCommandLineMode, $wgDebugDBTransactions;
 789
 790                 $this->mTrxAtomicLevels = new SplStack;
 791
 792                 $server = $params['host'];
 793                 $user = $params['user'];
 794                 $password = $params['password'];
 795                 $dbName = $params['dbname'];
 796                 $flags = $params['flags'];
 797                 $tablePrefix = $params['tablePrefix'];
 798                 $schema = $params['schema'];
 799                 $foreign = $params['foreign'];
 800
 801                 $this->mFlags = $flags;
 802                 if ( $this->mFlags & DBO_DEFAULT ) {
 803                         if ( $wgCommandLineMode ) {
 804                                 $this->mFlags &= ~DBO_TRX;
 805                                 if ( $wgDebugDBTransactions ) {
 806                                         wfDebug( "Implicit transaction open disabled.\n" );
 807                                 }
 808                         } else {
 809                                 $this->mFlags |= DBO_TRX;
 810                                 if ( $wgDebugDBTransactions ) {
 811                                         wfDebug( "Implicit transaction open enabled.\n" );
 812                                 }
 813                         }
 814                 }
 815
 816                 /** Get the default table prefix*/
 817                 if ( $tablePrefix == 'get from global' ) {
 818                         $this->mTablePrefix = $wgDBprefix;
 819                 } else {
 820                         $this->mTablePrefix = $tablePrefix;
 821                 }
 822
 823                 /** Get the database schema*/
 824                 if ( $schema == 'get from global' ) {
 825                         $this->mSchema = $wgDBmwschema;
 826                 } else {
 827                         $this->mSchema = $schema;
 828                 }
 829
 830                 $this->mForeign = $foreign;
 831
 832                 if ( isset( $params['trxProfiler'] ) ) {
 833                         $this->trxProfiler = $params['trxProfiler']; // override
 834                 }
 835
 836                 if ( $user ) {
 837                         $this->open( $server, $user, $password, $dbName );
 838                 }
 839         }
 840
 841         /**
 842          * Called by serialize. Throw an exception when DB connection is serialized.
 843          * This causes problems on some database engines because the connection is
 844          * not restored on unserialize.
 845          */
 846         public function __sleep() {
 847                 throw new MWException( 'Database serialization may cause problems, since ' .
 848                         'the connection is not restored on wakeup.' );
 849         }
 850
 851         /**
 852          * Given a DB type, construct the name of the appropriate child class of
 853          * DatabaseBase. This is designed to replace all of the manual stuff like:
 854          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 855          * as well as validate against the canonical list of DB types we have
 856          *
 857          * This factory function is mostly useful for when you need to connect to a
 858          * database other than the MediaWiki default (such as for external auth,
 859          * an extension, et cetera). Do not use this to connect to the MediaWiki
 860          * database. Example uses in core:
 861          * @see LoadBalancer::reallyOpenConnection()
 862          * @see ForeignDBRepo::getMasterDB()
 863          * @see WebInstallerDBConnect::execute()
 864          *
 865          * @since 1.18
 866          *
 867          * @param string $dbType A possible DB type
 868          * @param array $p An array of options to pass to the constructor.
 869          *    Valid options are: host, user, password, dbname, flags, tablePrefix, schema, driver
 870          * @throws MWException If the database driver or extension cannot be found
 871          * @return DatabaseBase|null DatabaseBase subclass or null
 872          */
 873         final public static function factory( $dbType, $p = array() ) {
 874                 $canonicalDBTypes = array(
 875                         'mysql' => array( 'mysqli', 'mysql' ),
 876                         'postgres' => array(),
 877                         'sqlite' => array(),
 878                         'oracle' => array(),
 879                         'mssql' => array(),
 880                 );
 881
 882                 $driver = false;
 883                 $dbType = strtolower( $dbType );
 884                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 885                         $possibleDrivers = $canonicalDBTypes[$dbType];
 886                         if ( !empty( $p['driver'] ) ) {
 887                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 888                                         $driver = $p['driver'];
 889                                 } else {
 890                                         throw new MWException( __METHOD__ .
 891                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 892                                 }
 893                         } else {
 894                                 foreach ( $possibleDrivers as $posDriver ) {
 895                                         if ( extension_loaded( $posDriver ) ) {
 896                                                 $driver = $posDriver;
 897                                                 break;
 898                                         }
 899                                 }
 900                         }
 901                 } else {
 902                         $driver = $dbType;
 903                 }
 904                 if ( $driver === false ) {
 905                         throw new MWException( __METHOD__ .
 906                                 " no viable database extension found for type '$dbType'" );
 907                 }
 908
 909                 // Determine schema defaults. Currently Microsoft SQL Server uses $wgDBmwschema,
 910                 // and everything else doesn't use a schema (e.g. null)
 911                 // Although postgres and oracle support schemas, we don't use them (yet)
 912                 // to maintain backwards compatibility
 913                 $defaultSchemas = array(
 914                         'mysql' => null,
 915                         'postgres' => null,
 916                         'sqlite' => null,
 917                         'oracle' => null,
 918                         'mssql' => 'get from global',
 919                 );
 920
 921                 $class = 'Database' . ucfirst( $driver );
 922                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 923                         // Resolve some defaults for b/c
 924                         $p['host'] = isset( $p['host'] ) ? $p['host'] : false;
 925                         $p['user'] = isset( $p['user'] ) ? $p['user'] : false;
 926                         $p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 927                         $p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 928                         $p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
 929                         $p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
 930                         $p['schema'] = isset( $p['schema'] ) ? $p['schema'] : $defaultSchemas[$dbType];
 931                         $p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 932
 933                         return new $class( $p );
 934                 } else {
 935                         return null;
 936                 }
 937         }
 938
 939         protected function installErrorHandler() {
 940                 $this->mPHPError = false;
 941                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 942                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 943         }
 944
 945         /**
 946          * @return bool|string
 947          */
 948         protected function restoreErrorHandler() {
 949                 restore_error_handler();
 950                 if ( $this->htmlErrors !== false ) {
 951                         ini_set( 'html_errors', $this->htmlErrors );
 952                 }
 953                 if ( $this->mPHPError ) {
 954                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 955                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 956
 957                         return $error;
 958                 } else {
 959                         return false;
 960                 }
 961         }
 962
 963         /**
 964          * @param int $errno
 965          * @param string $errstr
 966          */
 967         public function connectionErrorHandler( $errno, $errstr ) {
 968                 $this->mPHPError = $errstr;
 969         }
 970
 971         /**
 972          * Create a log context to pass to wfLogDBError or other logging functions.
 973          *
 974          * @param array $extras Additional data to add to context
 975          * @return array
 976          */
 977         protected function getLogContext( array $extras = array() ) {
 978                 return array_merge(
 979                         array(
 980                                 'db_server' => $this->mServer,
 981                                 'db_name' => $this->mDBname,
 982                                 'db_user' => $this->mUser,
 983                         ),
 984                         $extras
 985                 );
 986         }
 987
 988         /**
 989          * Closes a database connection.
 990          * if it is open : commits any open transactions
 991          *
 992          * @throws MWException
 993          * @return bool Operation success. true if already closed.
 994          */
 995         public function close() {
 996                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 997                         throw new MWException( "Transaction idle callbacks still pending." );
 998                 }
 999                 if ( $this->mConn ) {
1000                         if ( $this->trxLevel() ) {
1001                                 if ( !$this->mTrxAutomatic ) {
1002                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
1003                                                 " performing implicit commit before closing connection!" );
1004                                 }
1005
1006                                 $this->commit( __METHOD__, 'flush' );
1007                         }
1008
1009                         $closed = $this->closeConnection();
1010                         $this->mConn = false;
1011                 } else {
1012                         $closed = true;
1013                 }
1014                 $this->mOpened = false;
1015
1016                 return $closed;
1017         }
1018
1019         /**
1020          * Closes underlying database connection
1021          * @since 1.20
1022          * @return bool Whether connection was closed successfully
1023          */
1024         abstract protected function closeConnection();
1025
1026         /**
1027          * @param string $error Fallback error message, used if none is given by DB
1028          * @throws DBConnectionError
1029          */
1030         function reportConnectionError( $error = 'Unknown error' ) {
1031                 $myError = $this->lastError();
1032                 if ( $myError ) {
1033                         $error = $myError;
1034                 }
1035
1036                 # New method
1037                 throw new DBConnectionError( $this, $error );
1038         }
1039
1040         /**
1041          * The DBMS-dependent part of query()
1042          *
1043          * @param string $sql SQL query.
1044          * @return ResultWrapper|bool Result object to feed to fetchObject,
1045          *   fetchRow, ...; or false on failure
1046          */
1047         abstract protected function doQuery( $sql );
1048
1049         /**
1050          * Determine whether a query writes to the DB.
1051          * Should return true if unsure.
1052          *
1053          * @param string $sql
1054          * @return bool
1055          */
1056         public function isWriteQuery( $sql ) {
1057                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
1058         }
1059
1060         /**
1061          * Determine whether a SQL statement is sensitive to isolation level.
1062          * A SQL statement is considered transactable if its result could vary
1063          * depending on the transaction isolation level. Operational commands
1064          * such as 'SET' and 'SHOW' are not considered to be transactable.
1065          *
1066          * @param string $sql
1067          * @return bool
1068          */
1069         public function isTransactableQuery( $sql ) {
1070                 $verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
1071                 return !in_array( $verb, array( 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ) );
1072         }
1073
1074         /**
1075          * Run an SQL query and return the result. Normally throws a DBQueryError
1076          * on failure. If errors are ignored, returns false instead.
1077          *
1078          * In new code, the query wrappers select(), insert(), update(), delete(),
1079          * etc. should be used where possible, since they give much better DBMS
1080          * independence and automatically quote or validate user input in a variety
1081          * of contexts. This function is generally only useful for queries which are
1082          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
1083          * as CREATE TABLE.
1084          *
1085          * However, the query wrappers themselves should call this function.
1086          *
1087          * @param string $sql SQL query
1088          * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
1089          *     comment (you can use __METHOD__ or add some extra info)
1090          * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
1091          *     maybe best to catch the exception instead?
1092          * @throws MWException
1093          * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
1094          *     for a successful read query, or false on failure if $tempIgnore set
1095          */
1096         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
1097                 global $wgUser, $wgDebugDBTransactions, $wgDebugDumpSqlLength;
1098
1099                 $this->mLastQuery = $sql;
1100
1101                 $isWriteQuery = $this->isWriteQuery( $sql );
1102                 if ( $isWriteQuery ) {
1103                         if ( !$this->mDoneWrites ) {
1104                                 wfDebug( __METHOD__ . ': Writes done: ' .
1105                                         DatabaseBase::generalizeSQL( $sql ) . "\n" );
1106                         }
1107                         # Set a flag indicating that writes have been done
1108                         $this->mDoneWrites = microtime( true );
1109                 }
1110
1111                 # Add a comment for easy SHOW PROCESSLIST interpretation
1112                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
1113                         $userName = $wgUser->getName();
1114                         if ( mb_strlen( $userName ) > 15 ) {
1115                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
1116                         }
1117                         $userName = str_replace( '/', '', $userName );
1118                 } else {
1119                         $userName = '';
1120                 }
1121
1122                 // Add trace comment to the begin of the sql string, right after the operator.
1123                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
1124                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
1125
1126                 if ( !$this->mTrxLevel && $this->getFlag( DBO_TRX ) && $this->isTransactableQuery( $sql ) ) {
1127                         if ( $wgDebugDBTransactions ) {
1128                                 wfDebug( "Implicit transaction start.\n" );
1129                         }
1130                         $this->begin( __METHOD__ . " ($fname)" );
1131                         $this->mTrxAutomatic = true;
1132                 }
1133
1134                 # Keep track of whether the transaction has write queries pending
1135                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $isWriteQuery ) {
1136                         $this->mTrxDoneWrites = true;
1137                         $this->getTransactionProfiler()->transactionWritingIn(
1138                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
1139                 }
1140
1141                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1142                 # generalizeSQL will probably cut down the query to reasonable
1143                 # logging size most of the time. The substr is really just a sanity check.
1144                 if ( $isMaster ) {
1145                         $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1146                         $totalProf = 'DatabaseBase::query-master';
1147                 } else {
1148                         $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1149                         $totalProf = 'DatabaseBase::query';
1150                 }
1151                 # Include query transaction state
1152                 $queryProf .= $this->mTrxShortId ? " [TRX#{$this->mTrxShortId}]" : "";
1153
1154                 $profiler = Profiler::instance();
1155                 if ( !$profiler instanceof ProfilerStub ) {
1156                         $totalProfSection = $profiler->scopedProfileIn( $totalProf );
1157                         $queryProfSection = $profiler->scopedProfileIn( $queryProf );
1158                 }
1159
1160                 if ( $this->debug() ) {
1161                         static $cnt = 0;
1162
1163                         $cnt++;
1164                         $sqlx = $wgDebugDumpSqlLength ? substr( $commentedSql, 0, $wgDebugDumpSqlLength )
1165                                 : $commentedSql;
1166                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
1167
1168                         $master = $isMaster ? 'master' : 'slave';
1169                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
1170                 }
1171
1172                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
1173
1174                 # Avoid fatals if close() was called
1175                 if ( !$this->isOpen() ) {
1176                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
1177                 }
1178
1179                 # Do the query and handle errors
1180                 $startTime = microtime( true );
1181                 $ret = $this->doQuery( $commentedSql );
1182                 $queryRuntime = microtime( true ) - $startTime;
1183                 # Log the query time and feed it into the DB trx profiler
1184                 $this->getTransactionProfiler()->recordQueryCompletion(
1185                         $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
1186
1187                 MWDebug::queryTime( $queryId );
1188
1189                 # Try reconnecting if the connection was lost
1190                 if ( false === $ret && $this->wasErrorReissuable() ) {
1191                         # Transaction is gone, like it or not
1192                         $hadTrx = $this->mTrxLevel; // possible lost transaction
1193                         $this->mTrxLevel = 0;
1194                         $this->mTrxIdleCallbacks = array(); // bug 65263
1195                         $this->mTrxPreCommitCallbacks = array(); // bug 65263
1196                         wfDebug( "Connection lost, reconnecting...\n" );
1197                         # Stash the last error values since ping() might clear them
1198                         $lastError = $this->lastError();
1199                         $lastErrno = $this->lastErrno();
1200                         if ( $this->ping() ) {
1201                                 wfDebug( "Reconnected\n" );
1202                                 $server = $this->getServer();
1203                                 $msg = __METHOD__ . ": lost connection to $server; reconnected";
1204                                 wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
1205
1206                                 if ( $hadTrx ) {
1207                                         # Leave $ret as false and let an error be reported.
1208                                         # Callers may catch the exception and continue to use the DB.
1209                                         $this->reportQueryError( $lastError, $lastErrno, $sql, $fname, $tempIgnore );
1210                                 } else {
1211                                         # Should be safe to silently retry (no trx and thus no callbacks)
1212                                         $startTime = microtime( true );
1213                                         $ret = $this->doQuery( $commentedSql );
1214                                         $queryRuntime = microtime( true ) - $startTime;
1215                                         # Log the query time and feed it into the DB trx profiler
1216                                         $this->getTransactionProfiler()->recordQueryCompletion(
1217                                                 $queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
1218                                 }
1219                         } else {
1220                                 wfDebug( "Failed\n" );
1221                         }
1222                 }
1223
1224                 if ( false === $ret ) {
1225                         $this->reportQueryError(
1226                                 $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1227                 }
1228
1229                 $res = $this->resultObject( $ret );
1230
1231                 // Destroy profile sections in the opposite order to their creation
1232                 $queryProfSection = false;
1233                 $totalProfSection = false;
1234
1235                 if ( $isWriteQuery && $this->mTrxLevel ) {
1236                         $this->mTrxWriteDuration += $queryRuntime;
1237                 }
1238
1239                 return $res;
1240         }
1241
1242         /**
1243          * Report a query error. Log the error, and if neither the object ignore
1244          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1245          *
1246          * @param string $error
1247          * @param int $errno
1248          * @param string $sql
1249          * @param string $fname
1250          * @param bool $tempIgnore
1251          * @throws DBQueryError
1252          */
1253         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1254                 ++$this->mErrorCount;
1255
1256                 if ( $this->ignoreErrors() || $tempIgnore ) {
1257                         wfDebug( "SQL ERROR (ignored): $error\n" );
1258                 } else {
1259                         $sql1line = mb_substr( str_replace( "\n", "\\n", $sql ), 0, 5 * 1024 );
1260                         wfLogDBError(
1261                                 "{fname}\t{db_server}\t{errno}\t{error}\t{sql1line}",
1262                                 $this->getLogContext( array(
1263                                         'method' => __METHOD__,
1264                                         'errno' => $errno,
1265                                         'error' => $error,
1266                                         'sql1line' => $sql1line,
1267                                         'fname' => $fname,
1268                                 ) )
1269                         );
1270                         wfDebug( "SQL ERROR: " . $error . "\n" );
1271                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1272                 }
1273         }
1274
1275         /**
1276          * Intended to be compatible with the PEAR::DB wrapper functions.
1277          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1278          *
1279          * ? = scalar value, quoted as necessary
1280          * ! = raw SQL bit (a function for instance)
1281          * & = filename; reads the file and inserts as a blob
1282          *     (we don't use this though...)
1283          *
1284          * @param string $sql
1285          * @param string $func
1286          *
1287          * @return array
1288          */
1289         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1290                 /* MySQL doesn't support prepared statements (yet), so just
1291                  * pack up the query for reference. We'll manually replace
1292                  * the bits later.
1293                  */
1294                 return array( 'query' => $sql, 'func' => $func );
1295         }
1296
1297         /**
1298          * Free a prepared query, generated by prepare().
1299          * @param string $prepared
1300          */
1301         protected function freePrepared( $prepared ) {
1302                 /* No-op by default */
1303         }
1304
1305         /**
1306          * Execute a prepared query with the various arguments
1307          * @param string $prepared The prepared sql
1308          * @param mixed $args Either an array here, or put scalars as varargs
1309          *
1310          * @return ResultWrapper
1311          */
1312         public function execute( $prepared, $args = null ) {
1313                 if ( !is_array( $args ) ) {
1314                         # Pull the var args
1315                         $args = func_get_args();
1316                         array_shift( $args );
1317                 }
1318
1319                 $sql = $this->fillPrepared( $prepared['query'], $args );
1320
1321                 return $this->query( $sql, $prepared['func'] );
1322         }
1323
1324         /**
1325          * For faking prepared SQL statements on DBs that don't support it directly.
1326          *
1327          * @param string $preparedQuery A 'preparable' SQL statement
1328          * @param array $args Array of Arguments to fill it with
1329          * @return string Executable SQL
1330          */
1331         public function fillPrepared( $preparedQuery, $args ) {
1332                 reset( $args );
1333                 $this->preparedArgs =& $args;
1334
1335                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1336                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1337         }
1338
1339         /**
1340          * preg_callback func for fillPrepared()
1341          * The arguments should be in $this->preparedArgs and must not be touched
1342          * while we're doing this.
1343          *
1344          * @param array $matches
1345          * @throws DBUnexpectedError
1346          * @return string
1347          */
1348         protected function fillPreparedArg( $matches ) {
1349                 switch ( $matches[1] ) {
1350                         case '\\?':
1351                                 return '?';
1352                         case '\\!':
1353                                 return '!';
1354                         case '\\&':
1355                                 return '&';
1356                 }
1357
1358                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1359
1360                 switch ( $matches[1] ) {
1361                         case '?':
1362                                 return $this->addQuotes( $arg );
1363                         case '!':
1364                                 return $arg;
1365                         case '&':
1366                                 # return $this->addQuotes( file_get_contents( $arg ) );
1367                                 throw new DBUnexpectedError(
1368                                         $this,
1369                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1370                                 );
1371                         default:
1372                                 throw new DBUnexpectedError(
1373                                         $this,
1374                                         'Received invalid match. This should never happen!'
1375                                 );
1376                 }
1377         }
1378
1379         /**
1380          * Free a result object returned by query() or select(). It's usually not
1381          * necessary to call this, just use unset() or let the variable holding
1382          * the result object go out of scope.
1383          *
1384          * @param mixed $res A SQL result
1385          */
1386         public function freeResult( $res ) {
1387         }
1388
1389         /**
1390          * A SELECT wrapper which returns a single field from a single result row.
1391          *
1392          * Usually throws a DBQueryError on failure. If errors are explicitly
1393          * ignored, returns false on failure.
1394          *
1395          * If no result rows are returned from the query, false is returned.
1396          *
1397          * @param string|array $table Table name. See DatabaseBase::select() for details.
1398          * @param string $var The field name to select. This must be a valid SQL
1399          *   fragment: do not use unvalidated user input.
1400          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1401          * @param string $fname The function name of the caller.
1402          * @param string|array $options The query options. See DatabaseBase::select() for details.
1403          *
1404          * @return bool|mixed The value from the field, or false on failure.
1405          */
1406         public function selectField(
1407                 $table, $var, $cond = '', $fname = __METHOD__, $options = array()
1408         ) {
1409                 if ( $var === '*' ) { // sanity
1410                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1411                 }
1412
1413                 if ( !is_array( $options ) ) {
1414                         $options = array( $options );
1415                 }
1416
1417                 $options['LIMIT'] = 1;
1418
1419                 $res = $this->select( $table, $var, $cond, $fname, $options );
1420                 if ( $res === false || !$this->numRows( $res ) ) {
1421                         return false;
1422                 }
1423
1424                 $row = $this->fetchRow( $res );
1425
1426                 if ( $row !== false ) {
1427                         return reset( $row );
1428                 } else {
1429                         return false;
1430                 }
1431         }
1432
1433         /**
1434          * A SELECT wrapper which returns a list of single field values from result rows.
1435          *
1436          * Usually throws a DBQueryError on failure. If errors are explicitly
1437          * ignored, returns false on failure.
1438          *
1439          * If no result rows are returned from the query, false is returned.
1440          *
1441          * @param string|array $table Table name. See DatabaseBase::select() for details.
1442          * @param string $var The field name to select. This must be a valid SQL
1443          *   fragment: do not use unvalidated user input.
1444          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1445          * @param string $fname The function name of the caller.
1446          * @param string|array $options The query options. See DatabaseBase::select() for details.
1447          *
1448          * @return bool|array The values from the field, or false on failure
1449          * @since 1.25
1450          */
1451         public function selectFieldValues(
1452                 $table, $var, $cond = '', $fname = __METHOD__, $options = array()
1453         ) {
1454                 if ( $var === '*' ) { // sanity
1455                         throw new DBUnexpectedError( $this, "Cannot use a * field: got '$var'" );
1456                 }
1457
1458                 if ( !is_array( $options ) ) {
1459                         $options = array( $options );
1460                 }
1461
1462                 $res = $this->select( $table, $var, $cond, $fname, $options );
1463                 if ( $res === false ) {
1464                         return false;
1465                 }
1466
1467                 $values = array();
1468                 foreach ( $res as $row ) {
1469                         $values[] = $row->$var;
1470                 }
1471
1472                 return $values;
1473         }
1474
1475         /**
1476          * Returns an optional USE INDEX clause to go after the table, and a
1477          * string to go at the end of the query.
1478          *
1479          * @param array $options Associative array of options to be turned into
1480          *   an SQL query, valid keys are listed in the function.
1481          * @return array
1482          * @see DatabaseBase::select()
1483          */
1484         public function makeSelectOptions( $options ) {
1485                 $preLimitTail = $postLimitTail = '';
1486                 $startOpts = '';
1487
1488                 $noKeyOptions = array();
1489
1490                 foreach ( $options as $key => $option ) {
1491                         if ( is_numeric( $key ) ) {
1492                                 $noKeyOptions[$option] = true;
1493                         }
1494                 }
1495
1496                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1497
1498                 $preLimitTail .= $this->makeOrderBy( $options );
1499
1500                 // if (isset($options['LIMIT'])) {
1501                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1502                 //              isset($options['OFFSET']) ? $options['OFFSET']
1503                 //              : false);
1504                 // }
1505
1506                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1507                         $postLimitTail .= ' FOR UPDATE';
1508                 }
1509
1510                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1511                         $postLimitTail .= ' LOCK IN SHARE MODE';
1512                 }
1513
1514                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1515                         $startOpts .= 'DISTINCT';
1516                 }
1517
1518                 # Various MySQL extensions
1519                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1520                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1521                 }
1522
1523                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1524                         $startOpts .= ' HIGH_PRIORITY';
1525                 }
1526
1527                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1528                         $startOpts .= ' SQL_BIG_RESULT';
1529                 }
1530
1531                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1532                         $startOpts .= ' SQL_BUFFER_RESULT';
1533                 }
1534
1535                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1536                         $startOpts .= ' SQL_SMALL_RESULT';
1537                 }
1538
1539                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1540                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1541                 }
1542
1543                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1544                         $startOpts .= ' SQL_CACHE';
1545                 }
1546
1547                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1548                         $startOpts .= ' SQL_NO_CACHE';
1549                 }
1550
1551                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1552                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1553                 } else {
1554                         $useIndex = '';
1555                 }
1556
1557                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1558         }
1559
1560         /**
1561          * Returns an optional GROUP BY with an optional HAVING
1562          *
1563          * @param array $options Associative array of options
1564          * @return string
1565          * @see DatabaseBase::select()
1566          * @since 1.21
1567          */
1568         public function makeGroupByWithHaving( $options ) {
1569                 $sql = '';
1570                 if ( isset( $options['GROUP BY'] ) ) {
1571                         $gb = is_array( $options['GROUP BY'] )
1572                                 ? implode( ',', $options['GROUP BY'] )
1573                                 : $options['GROUP BY'];
1574                         $sql .= ' GROUP BY ' . $gb;
1575                 }
1576                 if ( isset( $options['HAVING'] ) ) {
1577                         $having = is_array( $options['HAVING'] )
1578                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1579                                 : $options['HAVING'];
1580                         $sql .= ' HAVING ' . $having;
1581                 }
1582
1583                 return $sql;
1584         }
1585
1586         /**
1587          * Returns an optional ORDER BY
1588          *
1589          * @param array $options Associative array of options
1590          * @return string
1591          * @see DatabaseBase::select()
1592          * @since 1.21
1593          */
1594         public function makeOrderBy( $options ) {
1595                 if ( isset( $options['ORDER BY'] ) ) {
1596                         $ob = is_array( $options['ORDER BY'] )
1597                                 ? implode( ',', $options['ORDER BY'] )
1598                                 : $options['ORDER BY'];
1599
1600                         return ' ORDER BY ' . $ob;
1601                 }
1602
1603                 return '';
1604         }
1605
1606         /**
1607          * Execute a SELECT query constructed using the various parameters provided.
1608          * See below for full details of the parameters.
1609          *
1610          * @param string|array $table Table name
1611          * @param string|array $vars Field names
1612          * @param string|array $conds Conditions
1613          * @param string $fname Caller function name
1614          * @param array $options Query options
1615          * @param array $join_conds Join conditions
1616          *
1617          *
1618          * @param string|array $table
1619          *
1620          * May be either an array of table names, or a single string holding a table
1621          * name. If an array is given, table aliases can be specified, for example:
1622          *
1623          *    array( 'a' => 'user' )
1624          *
1625          * This includes the user table in the query, with the alias "a" available
1626          * for use in field names (e.g. a.user_name).
1627          *
1628          * All of the table names given here are automatically run through
1629          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1630          * added, and various other table name mappings to be performed.
1631          *
1632          *
1633          * @param string|array $vars
1634          *
1635          * May be either a field name or an array of field names. The field names
1636          * can be complete fragments of SQL, for direct inclusion into the SELECT
1637          * query. If an array is given, field aliases can be specified, for example:
1638          *
1639          *   array( 'maxrev' => 'MAX(rev_id)' )
1640          *
1641          * This includes an expression with the alias "maxrev" in the query.
1642          *
1643          * If an expression is given, care must be taken to ensure that it is
1644          * DBMS-independent.
1645          *
1646          *
1647          * @param string|array $conds
1648          *
1649          * May be either a string containing a single condition, or an array of
1650          * conditions. If an array is given, the conditions constructed from each
1651          * element are combined with AND.
1652          *
1653          * Array elements may take one of two forms:
1654          *
1655          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1656          *   - Elements with a string key are interpreted as equality conditions,
1657          *     where the key is the field name.
1658          *     - If the value of such an array element is a scalar (such as a
1659          *       string), it will be treated as data and thus quoted appropriately.
1660          *       If it is null, an IS NULL clause will be added.
1661          *     - If the value is an array, an IN (...) clause will be constructed
1662          *       from its non-null elements, and an IS NULL clause will be added
1663          *       if null is present, such that the field may match any of the
1664          *       elements in the array. The non-null elements will be quoted.
1665          *
1666          * Note that expressions are often DBMS-dependent in their syntax.
1667          * DBMS-independent wrappers are provided for constructing several types of
1668          * expression commonly used in condition queries. See:
1669          *    - DatabaseBase::buildLike()
1670          *    - DatabaseBase::conditional()
1671          *
1672          *
1673          * @param string|array $options
1674          *
1675          * Optional: Array of query options. Boolean options are specified by
1676          * including them in the array as a string value with a numeric key, for
1677          * example:
1678          *
1679          *    array( 'FOR UPDATE' )
1680          *
1681          * The supported options are:
1682          *
1683          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1684          *     with LIMIT can theoretically be used for paging through a result set,
1685          *     but this is discouraged in MediaWiki for performance reasons.
1686          *
1687          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1688          *     and then the first rows are taken until the limit is reached. LIMIT
1689          *     is applied to a result set after OFFSET.
1690          *
1691          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1692          *     changed until the next COMMIT.
1693          *
1694          *   - DISTINCT: Boolean: return only unique result rows.
1695          *
1696          *   - GROUP BY: May be either an SQL fragment string naming a field or
1697          *     expression to group by, or an array of such SQL fragments.
1698          *
1699          *   - HAVING: May be either an string containing a HAVING clause or an array of
1700          *     conditions building the HAVING clause. If an array is given, the conditions
1701          *     constructed from each element are combined with AND.
1702          *
1703          *   - ORDER BY: May be either an SQL fragment giving a field name or
1704          *     expression to order by, or an array of such SQL fragments.
1705          *
1706          *   - USE INDEX: This may be either a string giving the index name to use
1707          *     for the query, or an array. If it is an associative array, each key
1708          *     gives the table name (or alias), each value gives the index name to
1709          *     use for that table. All strings are SQL fragments and so should be
1710          *     validated by the caller.
1711          *
1712          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1713          *     instead of SELECT.
1714          *
1715          * And also the following boolean MySQL extensions, see the MySQL manual
1716          * for documentation:
1717          *
1718          *    - LOCK IN SHARE MODE
1719          *    - STRAIGHT_JOIN
1720          *    - HIGH_PRIORITY
1721          *    - SQL_BIG_RESULT
1722          *    - SQL_BUFFER_RESULT
1723          *    - SQL_SMALL_RESULT
1724          *    - SQL_CALC_FOUND_ROWS
1725          *    - SQL_CACHE
1726          *    - SQL_NO_CACHE
1727          *
1728          *
1729          * @param string|array $join_conds
1730          *
1731          * Optional associative array of table-specific join conditions. In the
1732          * most common case, this is unnecessary, since the join condition can be
1733          * in $conds. However, it is useful for doing a LEFT JOIN.
1734          *
1735          * The key of the array contains the table name or alias. The value is an
1736          * array with two elements, numbered 0 and 1. The first gives the type of
1737          * join, the second is an SQL fragment giving the join condition for that
1738          * table. For example:
1739          *
1740          *    array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )
1741          *
1742          * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
1743          *   with no rows in it will be returned. If there was a query error, a
1744          *   DBQueryError exception will be thrown, except if the "ignore errors"
1745          *   option was set, in which case false will be returned.
1746          */
1747         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1748                 $options = array(), $join_conds = array() ) {
1749                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1750
1751                 return $this->query( $sql, $fname );
1752         }
1753
1754         /**
1755          * The equivalent of DatabaseBase::select() except that the constructed SQL
1756          * is returned, instead of being immediately executed. This can be useful for
1757          * doing UNION queries, where the SQL text of each query is needed. In general,
1758          * however, callers outside of Database classes should just use select().
1759          *
1760          * @param string|array $table Table name
1761          * @param string|array $vars Field names
1762          * @param string|array $conds Conditions
1763          * @param string $fname Caller function name
1764          * @param string|array $options Query options
1765          * @param string|array $join_conds Join conditions
1766          *
1767          * @return string SQL query string.
1768          * @see DatabaseBase::select()
1769          */
1770         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1771                 $options = array(), $join_conds = array()
1772         ) {
1773                 if ( is_array( $vars ) ) {
1774                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1775                 }
1776
1777                 $options = (array)$options;
1778                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1779                         ? $options['USE INDEX']
1780                         : array();
1781
1782                 if ( is_array( $table ) ) {
1783                         $from = ' FROM ' .
1784                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1785                 } elseif ( $table != '' ) {
1786                         if ( $table[0] == ' ' ) {
1787                                 $from = ' FROM ' . $table;
1788                         } else {
1789                                 $from = ' FROM ' .
1790                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1791                         }
1792                 } else {
1793                         $from = '';
1794                 }
1795
1796                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1797                         $this->makeSelectOptions( $options );
1798
1799                 if ( !empty( $conds ) ) {
1800                         if ( is_array( $conds ) ) {
1801                                 $conds = $this->makeList( $conds, LIST_AND );
1802                         }
1803                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1804                 } else {
1805                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1806                 }
1807
1808                 if ( isset( $options['LIMIT'] ) ) {
1809                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1810                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1811                 }
1812                 $sql = "$sql $postLimitTail";
1813
1814                 if ( isset( $options['EXPLAIN'] ) ) {
1815                         $sql = 'EXPLAIN ' . $sql;
1816                 }
1817
1818                 return $sql;
1819         }
1820
1821         /**
1822          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1823          * that a single row object is returned. If the query returns no rows,
1824          * false is returned.
1825          *
1826          * @param string|array $table Table name
1827          * @param string|array $vars Field names
1828          * @param array $conds Conditions
1829          * @param string $fname Caller function name
1830          * @param string|array $options Query options
1831          * @param array|string $join_conds Join conditions
1832          *
1833          * @return stdClass|bool
1834          */
1835         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1836                 $options = array(), $join_conds = array()
1837         ) {
1838                 $options = (array)$options;
1839                 $options['LIMIT'] = 1;
1840                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1841
1842                 if ( $res === false ) {
1843                         return false;
1844                 }
1845
1846                 if ( !$this->numRows( $res ) ) {
1847                         return false;
1848                 }
1849
1850                 $obj = $this->fetchObject( $res );
1851
1852                 return $obj;
1853         }
1854
1855         /**
1856          * Estimate the number of rows in dataset
1857          *
1858          * MySQL allows you to estimate the number of rows that would be returned
1859          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1860          * index cardinality statistics, and is notoriously inaccurate, especially
1861          * when large numbers of rows have recently been added or deleted.
1862          *
1863          * For DBMSs that don't support fast result size estimation, this function
1864          * will actually perform the SELECT COUNT(*).
1865          *
1866          * Takes the same arguments as DatabaseBase::select().
1867          *
1868          * @param string $table Table name
1869          * @param string $vars Unused
1870          * @param array|string $conds Filters on the table
1871          * @param string $fname Function name for profiling
1872          * @param array $options Options for select
1873          * @return int Row count
1874          */
1875         public function estimateRowCount(
1876                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
1877         ) {
1878                 $rows = 0;
1879                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1880
1881                 if ( $res ) {
1882                         $row = $this->fetchRow( $res );
1883                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1884                 }
1885
1886                 return $rows;
1887         }
1888
1889         /**
1890          * Get the number of rows in dataset
1891          *
1892          * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
1893          *
1894          * Takes the same arguments as DatabaseBase::select().
1895          *
1896          * @param string $table Table name
1897          * @param string $vars Unused
1898          * @param array|string $conds Filters on the table
1899          * @param string $fname Function name for profiling
1900          * @param array $options Options for select
1901          * @return int Row count
1902          * @since 1.24
1903          */
1904         public function selectRowCount(
1905                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
1906         ) {
1907                 $rows = 0;
1908                 $sql = $this->selectSQLText( $table, '1', $conds, $fname, $options );
1909                 $res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count" );
1910
1911                 if ( $res ) {
1912                         $row = $this->fetchRow( $res );
1913                         $rows = ( isset( $row['rowcount'] ) ) ? (int)$row['rowcount'] : 0;
1914                 }
1915
1916                 return $rows;
1917         }
1918
1919         /**
1920          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1921          * It's only slightly flawed. Don't use for anything important.
1922          *
1923          * @param string $sql A SQL Query
1924          *
1925          * @return string
1926          */
1927         static function generalizeSQL( $sql ) {
1928                 # This does the same as the regexp below would do, but in such a way
1929                 # as to avoid crashing php on some large strings.
1930                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1931
1932                 $sql = str_replace( "\\\\", '', $sql );
1933                 $sql = str_replace( "\\'", '', $sql );
1934                 $sql = str_replace( "\\\"", '', $sql );
1935                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1936                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1937
1938                 # All newlines, tabs, etc replaced by single space
1939                 $sql = preg_replace( '/\s+/', ' ', $sql );
1940
1941                 # All numbers => N,
1942                 # except the ones surrounded by characters, e.g. l10n
1943                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1944                 $sql = preg_replace( '/(?<![a-zA-Z])-?\d+(?![a-zA-Z])/s', 'N', $sql );
1945
1946                 return $sql;
1947         }
1948
1949         /**
1950          * Determines whether a field exists in a table
1951          *
1952          * @param string $table Table name
1953          * @param string $field Filed to check on that table
1954          * @param string $fname Calling function name (optional)
1955          * @return bool Whether $table has filed $field
1956          */
1957         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1958                 $info = $this->fieldInfo( $table, $field );
1959
1960                 return (bool)$info;
1961         }
1962
1963         /**
1964          * Determines whether an index exists
1965          * Usually throws a DBQueryError on failure
1966          * If errors are explicitly ignored, returns NULL on failure
1967          *
1968          * @param string $table
1969          * @param string $index
1970          * @param string $fname
1971          * @return bool|null
1972          */
1973         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1974                 if ( !$this->tableExists( $table ) ) {
1975                         return null;
1976                 }
1977
1978                 $info = $this->indexInfo( $table, $index, $fname );
1979                 if ( is_null( $info ) ) {
1980                         return null;
1981                 } else {
1982                         return $info !== false;
1983                 }
1984         }
1985
1986         /**
1987          * Query whether a given table exists
1988          *
1989          * @param string $table
1990          * @param string $fname
1991          * @return bool
1992          */
1993         public function tableExists( $table, $fname = __METHOD__ ) {
1994                 $table = $this->tableName( $table );
1995                 $old = $this->ignoreErrors( true );
1996                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1997                 $this->ignoreErrors( $old );
1998
1999                 return (bool)$res;
2000         }
2001
2002         /**
2003          * Determines if a given index is unique
2004          *
2005          * @param string $table
2006          * @param string $index
2007          *
2008          * @return bool
2009          */
2010         public function indexUnique( $table, $index ) {
2011                 $indexInfo = $this->indexInfo( $table, $index );
2012
2013                 if ( !$indexInfo ) {
2014                         return null;
2015                 }
2016
2017                 return !$indexInfo[0]->Non_unique;
2018         }
2019
2020         /**
2021          * Helper for DatabaseBase::insert().
2022          *
2023          * @param array $options
2024          * @return string
2025          */
2026         protected function makeInsertOptions( $options ) {
2027                 return implode( ' ', $options );
2028         }
2029
2030         /**
2031          * INSERT wrapper, inserts an array into a table.
2032          *
2033          * $a may be either:
2034          *
2035          *   - A single associative array. The array keys are the field names, and
2036          *     the values are the values to insert. The values are treated as data
2037          *     and will be quoted appropriately. If NULL is inserted, this will be
2038          *     converted to a database NULL.
2039          *   - An array with numeric keys, holding a list of associative arrays.
2040          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2041          *     each subarray must be identical to each other, and in the same order.
2042          *
2043          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2044          * returns success.
2045          *
2046          * $options is an array of options, with boolean options encoded as values
2047          * with numeric keys, in the same style as $options in
2048          * DatabaseBase::select(). Supported options are:
2049          *
2050          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
2051          *     any rows which cause duplicate key errors are not inserted. It's
2052          *     possible to determine how many rows were successfully inserted using
2053          *     DatabaseBase::affectedRows().
2054          *
2055          * @param string $table Table name. This will be passed through
2056          *   DatabaseBase::tableName().
2057          * @param array $a Array of rows to insert
2058          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2059          * @param array $options Array of options
2060          *
2061          * @return bool
2062          */
2063         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
2064                 # No rows to insert, easy just return now
2065                 if ( !count( $a ) ) {
2066                         return true;
2067                 }
2068
2069                 $table = $this->tableName( $table );
2070
2071                 if ( !is_array( $options ) ) {
2072                         $options = array( $options );
2073                 }
2074
2075                 $fh = null;
2076                 if ( isset( $options['fileHandle'] ) ) {
2077                         $fh = $options['fileHandle'];
2078                 }
2079                 $options = $this->makeInsertOptions( $options );
2080
2081                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
2082                         $multi = true;
2083                         $keys = array_keys( $a[0] );
2084                 } else {
2085                         $multi = false;
2086                         $keys = array_keys( $a );
2087                 }
2088
2089                 $sql = 'INSERT ' . $options .
2090                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
2091
2092                 if ( $multi ) {
2093                         $first = true;
2094                         foreach ( $a as $row ) {
2095                                 if ( $first ) {
2096                                         $first = false;
2097                                 } else {
2098                                         $sql .= ',';
2099                                 }
2100                                 $sql .= '(' . $this->makeList( $row ) . ')';
2101                         }
2102                 } else {
2103                         $sql .= '(' . $this->makeList( $a ) . ')';
2104                 }
2105
2106                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
2107                         return false;
2108                 } elseif ( $fh !== null ) {
2109                         return true;
2110                 }
2111
2112                 return (bool)$this->query( $sql, $fname );
2113         }
2114
2115         /**
2116          * Make UPDATE options array for DatabaseBase::makeUpdateOptions
2117          *
2118          * @param array $options
2119          * @return array
2120          */
2121         protected function makeUpdateOptionsArray( $options ) {
2122                 if ( !is_array( $options ) ) {
2123                         $options = array( $options );
2124                 }
2125
2126                 $opts = array();
2127
2128                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
2129                         $opts[] = $this->lowPriorityOption();
2130                 }
2131
2132                 if ( in_array( 'IGNORE', $options ) ) {
2133                         $opts[] = 'IGNORE';
2134                 }
2135
2136                 return $opts;
2137         }
2138
2139         /**
2140          * Make UPDATE options for the DatabaseBase::update function
2141          *
2142          * @param array $options The options passed to DatabaseBase::update
2143          * @return string
2144          */
2145         protected function makeUpdateOptions( $options ) {
2146                 $opts = $this->makeUpdateOptionsArray( $options );
2147
2148                 return implode( ' ', $opts );
2149         }
2150
2151         /**
2152          * UPDATE wrapper. Takes a condition array and a SET array.
2153          *
2154          * @param string $table Name of the table to UPDATE. This will be passed through
2155          *   DatabaseBase::tableName().
2156          * @param array $values An array of values to SET. For each array element,
2157          *   the key gives the field name, and the value gives the data to set
2158          *   that field to. The data will be quoted by DatabaseBase::addQuotes().
2159          * @param array $conds An array of conditions (WHERE). See
2160          *   DatabaseBase::select() for the details of the format of condition
2161          *   arrays. Use '*' to update all rows.
2162          * @param string $fname The function name of the caller (from __METHOD__),
2163          *   for logging and profiling.
2164          * @param array $options An array of UPDATE options, can be:
2165          *   - IGNORE: Ignore unique key conflicts
2166          *   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
2167          * @return bool
2168          */
2169         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
2170                 $table = $this->tableName( $table );
2171                 $opts = $this->makeUpdateOptions( $options );
2172                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
2173
2174                 if ( $conds !== array() && $conds !== '*' ) {
2175                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
2176                 }
2177
2178                 return $this->query( $sql, $fname );
2179         }
2180
2181         /**
2182          * Makes an encoded list of strings from an array
2183          *
2184          * @param array $a Containing the data
2185          * @param int $mode Constant
2186          *    - LIST_COMMA: Comma separated, no field names
2187          *    - LIST_AND:   ANDed WHERE clause (without the WHERE). See the
2188          *      documentation for $conds in DatabaseBase::select().
2189          *    - LIST_OR:    ORed WHERE clause (without the WHERE)
2190          *    - LIST_SET:   Comma separated with field names, like a SET clause
2191          *    - LIST_NAMES: Comma separated field names
2192          * @throws MWException|DBUnexpectedError
2193          * @return string
2194          */
2195         public function makeList( $a, $mode = LIST_COMMA ) {
2196                 if ( !is_array( $a ) ) {
2197                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
2198                 }
2199
2200                 $first = true;
2201                 $list = '';
2202
2203                 foreach ( $a as $field => $value ) {
2204                         if ( !$first ) {
2205                                 if ( $mode == LIST_AND ) {
2206                                         $list .= ' AND ';
2207                                 } elseif ( $mode == LIST_OR ) {
2208                                         $list .= ' OR ';
2209                                 } else {
2210                                         $list .= ',';
2211                                 }
2212                         } else {
2213                                 $first = false;
2214                         }
2215
2216                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
2217                                 $list .= "($value)";
2218                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
2219                                 $list .= "$value";
2220                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
2221                                 // Remove null from array to be handled separately if found
2222                                 $includeNull = false;
2223                                 foreach ( array_keys( $value, null, true ) as $nullKey ) {
2224                                         $includeNull = true;
2225                                         unset( $value[$nullKey] );
2226                                 }
2227                                 if ( count( $value ) == 0 && !$includeNull ) {
2228                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
2229                                 } elseif ( count( $value ) == 0 ) {
2230                                         // only check if $field is null
2231                                         $list .= "$field IS NULL";
2232                                 } else {
2233                                         // IN clause contains at least one valid element
2234                                         if ( $includeNull ) {
2235                                                 // Group subconditions to ensure correct precedence
2236                                                 $list .= '(';
2237                                         }
2238                                         if ( count( $value ) == 1 ) {
2239                                                 // Special-case single values, as IN isn't terribly efficient
2240                                                 // Don't necessarily assume the single key is 0; we don't
2241                                                 // enforce linear numeric ordering on other arrays here.
2242                                                 $value = array_values( $value );
2243                                                 $list .= $field . " = " . $this->addQuotes( $value[0] );
2244                                         } else {
2245                                                 $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2246                                         }
2247                                         // if null present in array, append IS NULL
2248                                         if ( $includeNull ) {
2249                                                 $list .= " OR $field IS NULL)";
2250                                         }
2251                                 }
2252                         } elseif ( $value === null ) {
2253                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
2254                                         $list .= "$field IS ";
2255                                 } elseif ( $mode == LIST_SET ) {
2256                                         $list .= "$field = ";
2257                                 }
2258                                 $list .= 'NULL';
2259                         } else {
2260                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
2261                                         $list .= "$field = ";
2262                                 }
2263                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
2264                         }
2265                 }
2266
2267                 return $list;
2268         }
2269
2270         /**
2271          * Build a partial where clause from a 2-d array such as used for LinkBatch.
2272          * The keys on each level may be either integers or strings.
2273          *
2274          * @param array $data Organized as 2-d
2275          *    array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
2276          * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
2277          * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
2278          * @return string|bool SQL fragment, or false if no items in array
2279          */
2280         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2281                 $conds = array();
2282
2283                 foreach ( $data as $base => $sub ) {
2284                         if ( count( $sub ) ) {
2285                                 $conds[] = $this->makeList(
2286                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
2287                                         LIST_AND );
2288                         }
2289                 }
2290
2291                 if ( $conds ) {
2292                         return $this->makeList( $conds, LIST_OR );
2293                 } else {
2294                         // Nothing to search for...
2295                         return false;
2296                 }
2297         }
2298
2299         /**
2300          * Return aggregated value alias
2301          *
2302          * @param array $valuedata
2303          * @param string $valuename
2304          *
2305          * @return string
2306          */
2307         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2308                 return $valuename;
2309         }
2310
2311         /**
2312          * @param string $field
2313          * @return string
2314          */
2315         public function bitNot( $field ) {
2316                 return "(~$field)";
2317         }
2318
2319         /**
2320          * @param string $fieldLeft
2321          * @param string $fieldRight
2322          * @return string
2323          */
2324         public function bitAnd( $fieldLeft, $fieldRight ) {
2325                 return "($fieldLeft & $fieldRight)";
2326         }
2327
2328         /**
2329          * @param string $fieldLeft
2330          * @param string $fieldRight
2331          * @return string
2332          */
2333         public function bitOr( $fieldLeft, $fieldRight ) {
2334                 return "($fieldLeft | $fieldRight)";
2335         }
2336
2337         /**
2338          * Build a concatenation list to feed into a SQL query
2339          * @param array $stringList List of raw SQL expressions; caller is
2340          *   responsible for any quoting
2341          * @return string
2342          */
2343         public function buildConcat( $stringList ) {
2344                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2345         }
2346
2347         /**
2348          * Build a GROUP_CONCAT or equivalent statement for a query.
2349          *
2350          * This is useful for combining a field for several rows into a single string.
2351          * NULL values will not appear in the output, duplicated values will appear,
2352          * and the resulting delimiter-separated values have no defined sort order.
2353          * Code using the results may need to use the PHP unique() or sort() methods.
2354          *
2355          * @param string $delim Glue to bind the results together
2356          * @param string|array $table Table name
2357          * @param string $field Field name
2358          * @param string|array $conds Conditions
2359          * @param string|array $join_conds Join conditions
2360          * @return string SQL text
2361          * @since 1.23
2362          */
2363         public function buildGroupConcatField(
2364                 $delim, $table, $field, $conds = '', $join_conds = array()
2365         ) {
2366                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2367
2368                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, array(), $join_conds ) . ')';
2369         }
2370
2371         /**
2372          * Change the current database
2373          *
2374          * @todo Explain what exactly will fail if this is not overridden.
2375          *
2376          * @param string $db
2377          *
2378          * @return bool Success or failure
2379          */
2380         public function selectDB( $db ) {
2381                 # Stub. Shouldn't cause serious problems if it's not overridden, but
2382                 # if your database engine supports a concept similar to MySQL's
2383                 # databases you may as well.
2384                 $this->mDBname = $db;
2385
2386                 return true;
2387         }
2388
2389         /**
2390          * Get the current DB name
2391          * @return string
2392          */
2393         public function getDBname() {
2394                 return $this->mDBname;
2395         }
2396
2397         /**
2398          * Get the server hostname or IP address
2399          * @return string
2400          */
2401         public function getServer() {
2402                 return $this->mServer;
2403         }
2404
2405         /**
2406          * Format a table name ready for use in constructing an SQL query
2407          *
2408          * This does two important things: it quotes the table names to clean them up,
2409          * and it adds a table prefix if only given a table name with no quotes.
2410          *
2411          * All functions of this object which require a table name call this function
2412          * themselves. Pass the canonical name to such functions. This is only needed
2413          * when calling query() directly.
2414          *
2415          * @param string $name Database table name
2416          * @param string $format One of:
2417          *   quoted - Automatically pass the table name through addIdentifierQuotes()
2418          *            so that it can be used in a query.
2419          *   raw - Do not add identifier quotes to the table name
2420          * @return string Full database name
2421          */
2422         public function tableName( $name, $format = 'quoted' ) {
2423                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables, $wgSharedSchema;
2424                 # Skip the entire process when we have a string quoted on both ends.
2425                 # Note that we check the end so that we will still quote any use of
2426                 # use of `database`.table. But won't break things if someone wants
2427                 # to query a database table with a dot in the name.
2428                 if ( $this->isQuotedIdentifier( $name ) ) {
2429                         return $name;
2430                 }
2431
2432                 # Lets test for any bits of text that should never show up in a table
2433                 # name. Basically anything like JOIN or ON which are actually part of
2434                 # SQL queries, but may end up inside of the table value to combine
2435                 # sql. Such as how the API is doing.
2436                 # Note that we use a whitespace test rather than a \b test to avoid
2437                 # any remote case where a word like on may be inside of a table name
2438                 # surrounded by symbols which may be considered word breaks.
2439                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2440                         return $name;
2441                 }
2442
2443                 # Split database and table into proper variables.
2444                 # We reverse the explode so that database.table and table both output
2445                 # the correct table.
2446                 $dbDetails = explode( '.', $name, 3 );
2447                 if ( count( $dbDetails ) == 3 ) {
2448                         list( $database, $schema, $table ) = $dbDetails;
2449                         # We don't want any prefix added in this case
2450                         $prefix = '';
2451                 } elseif ( count( $dbDetails ) == 2 ) {
2452                         list( $database, $table ) = $dbDetails;
2453                         # We don't want any prefix added in this case
2454                         # In dbs that support it, $database may actually be the schema
2455                         # but that doesn't affect any of the functionality here
2456                         $prefix = '';
2457                         $schema = null;
2458                 } else {
2459                         list( $table ) = $dbDetails;
2460                         if ( $wgSharedDB !== null # We have a shared database
2461                                 && $this->mForeign == false # We're not working on a foreign database
2462                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
2463                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
2464                         ) {
2465                                 $database = $wgSharedDB;
2466                                 $schema = $wgSharedSchema === null ? $this->mSchema : $wgSharedSchema;
2467                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
2468                         } else {
2469                                 $database = null;
2470                                 $schema = $this->mSchema; # Default schema
2471                                 $prefix = $this->mTablePrefix; # Default prefix
2472                         }
2473                 }
2474
2475                 # Quote $table and apply the prefix if not quoted.
2476                 # $tableName might be empty if this is called from Database::replaceVars()
2477                 $tableName = "{$prefix}{$table}";
2478                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) && $tableName !== '' ) {
2479                         $tableName = $this->addIdentifierQuotes( $tableName );
2480                 }
2481
2482                 # Quote $schema and merge it with the table name if needed
2483                 if ( $schema !== null ) {
2484                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
2485                                 $schema = $this->addIdentifierQuotes( $schema );
2486                         }
2487                         $tableName = $schema . '.' . $tableName;
2488                 }
2489
2490                 # Quote $database and merge it with the table name if needed
2491                 if ( $database !== null ) {
2492                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
2493                                 $database = $this->addIdentifierQuotes( $database );
2494                         }
2495                         $tableName = $database . '.' . $tableName;
2496                 }
2497
2498                 return $tableName;
2499         }
2500
2501         /**
2502          * Fetch a number of table names into an array
2503          * This is handy when you need to construct SQL for joins
2504          *
2505          * Example:
2506          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
2507          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2508          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2509          *
2510          * @return array
2511          */
2512         public function tableNames() {
2513                 $inArray = func_get_args();
2514                 $retVal = array();
2515
2516                 foreach ( $inArray as $name ) {
2517                         $retVal[$name] = $this->tableName( $name );
2518                 }
2519
2520                 return $retVal;
2521         }
2522
2523         /**
2524          * Fetch a number of table names into an zero-indexed numerical array
2525          * This is handy when you need to construct SQL for joins
2526          *
2527          * Example:
2528          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
2529          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2530          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2531          *
2532          * @return array
2533          */
2534         public function tableNamesN() {
2535                 $inArray = func_get_args();
2536                 $retVal = array();
2537
2538                 foreach ( $inArray as $name ) {
2539                         $retVal[] = $this->tableName( $name );
2540                 }
2541
2542                 return $retVal;
2543         }
2544
2545         /**
2546          * Get an aliased table name
2547          * e.g. tableName AS newTableName
2548          *
2549          * @param string $name Table name, see tableName()
2550          * @param string|bool $alias Alias (optional)
2551          * @return string SQL name for aliased table. Will not alias a table to its own name
2552          */
2553         public function tableNameWithAlias( $name, $alias = false ) {
2554                 if ( !$alias || $alias == $name ) {
2555                         return $this->tableName( $name );
2556                 } else {
2557                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2558                 }
2559         }
2560
2561         /**
2562          * Gets an array of aliased table names
2563          *
2564          * @param array $tables Array( [alias] => table )
2565          * @return string[] See tableNameWithAlias()
2566          */
2567         public function tableNamesWithAlias( $tables ) {
2568                 $retval = array();
2569                 foreach ( $tables as $alias => $table ) {
2570                         if ( is_numeric( $alias ) ) {
2571                                 $alias = $table;
2572                         }
2573                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2574                 }
2575
2576                 return $retval;
2577         }
2578
2579         /**
2580          * Get an aliased field name
2581          * e.g. fieldName AS newFieldName
2582          *
2583          * @param string $name Field name
2584          * @param string|bool $alias Alias (optional)
2585          * @return string SQL name for aliased field. Will not alias a field to its own name
2586          */
2587         public function fieldNameWithAlias( $name, $alias = false ) {
2588                 if ( !$alias || (string)$alias === (string)$name ) {
2589                         return $name;
2590                 } else {
2591                         return $name . ' AS ' . $alias; //PostgreSQL needs AS
2592                 }
2593         }
2594
2595         /**
2596          * Gets an array of aliased field names
2597          *
2598          * @param array $fields Array( [alias] => field )
2599          * @return string[] See fieldNameWithAlias()
2600          */
2601         public function fieldNamesWithAlias( $fields ) {
2602                 $retval = array();
2603                 foreach ( $fields as $alias => $field ) {
2604                         if ( is_numeric( $alias ) ) {
2605                                 $alias = $field;
2606                         }
2607                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2608                 }
2609
2610                 return $retval;
2611         }
2612
2613         /**
2614          * Get the aliased table name clause for a FROM clause
2615          * which might have a JOIN and/or USE INDEX clause
2616          *
2617          * @param array $tables ( [alias] => table )
2618          * @param array $use_index Same as for select()
2619          * @param array $join_conds Same as for select()
2620          * @return string
2621          */
2622         protected function tableNamesWithUseIndexOrJOIN(
2623                 $tables, $use_index = array(), $join_conds = array()
2624         ) {
2625                 $ret = array();
2626                 $retJOIN = array();
2627                 $use_index = (array)$use_index;
2628                 $join_conds = (array)$join_conds;
2629
2630                 foreach ( $tables as $alias => $table ) {
2631                         if ( !is_string( $alias ) ) {
2632                                 // No alias? Set it equal to the table name
2633                                 $alias = $table;
2634                         }
2635                         // Is there a JOIN clause for this table?
2636                         if ( isset( $join_conds[$alias] ) ) {
2637                                 list( $joinType, $conds ) = $join_conds[$alias];
2638                                 $tableClause = $joinType;
2639                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2640                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2641                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2642                                         if ( $use != '' ) {
2643                                                 $tableClause .= ' ' . $use;
2644                                         }
2645                                 }
2646                                 $on = $this->makeList( (array)$conds, LIST_AND );
2647                                 if ( $on != '' ) {
2648                                         $tableClause .= ' ON (' . $on . ')';
2649                                 }
2650
2651                                 $retJOIN[] = $tableClause;
2652                         } elseif ( isset( $use_index[$alias] ) ) {
2653                                 // Is there an INDEX clause for this table?
2654                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2655                                 $tableClause .= ' ' . $this->useIndexClause(
2656                                         implode( ',', (array)$use_index[$alias] )
2657                                 );
2658
2659                                 $ret[] = $tableClause;
2660                         } else {
2661                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2662
2663                                 $ret[] = $tableClause;
2664                         }
2665                 }
2666
2667                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2668                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2669                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2670
2671                 // Compile our final table clause
2672                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
2673         }
2674
2675         /**
2676          * Get the name of an index in a given table.
2677          *
2678          * @protected Don't use outside of DatabaseBase and childs
2679          * @param string $index
2680          * @return string
2681          */
2682         public function indexName( $index ) {
2683                 // @FIXME: Make this protected once we move away from PHP 5.3
2684                 // Needs to be public because of usage in closure (in DatabaseBase::replaceVars)
2685
2686                 // Backwards-compatibility hack
2687                 $renamed = array(
2688                         'ar_usertext_timestamp' => 'usertext_timestamp',
2689                         'un_user_id' => 'user_id',
2690                         'un_user_ip' => 'user_ip',
2691                 );
2692
2693                 if ( isset( $renamed[$index] ) ) {
2694                         return $renamed[$index];
2695                 } else {
2696                         return $index;
2697                 }
2698         }
2699
2700         /**
2701          * Adds quotes and backslashes.
2702          *
2703          * @param string|Blob $s
2704          * @return string
2705          */
2706         public function addQuotes( $s ) {
2707                 if ( $s instanceof Blob ) {
2708                         $s = $s->fetch();
2709                 }
2710                 if ( $s === null ) {
2711                         return 'NULL';
2712                 } else {
2713                         # This will also quote numeric values. This should be harmless,
2714                         # and protects against weird problems that occur when they really
2715                         # _are_ strings such as article titles and string->number->string
2716                         # conversion is not 1:1.
2717                         return "'" . $this->strencode( $s ) . "'";
2718                 }
2719         }
2720
2721         /**
2722          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2723          * MySQL uses `backticks` while basically everything else uses double quotes.
2724          * Since MySQL is the odd one out here the double quotes are our generic
2725          * and we implement backticks in DatabaseMysql.
2726          *
2727          * @param string $s
2728          * @return string
2729          */
2730         public function addIdentifierQuotes( $s ) {
2731                 return '"' . str_replace( '"', '""', $s ) . '"';
2732         }
2733
2734         /**
2735          * Returns if the given identifier looks quoted or not according to
2736          * the database convention for quoting identifiers .
2737          *
2738          * @param string $name
2739          * @return bool
2740          */
2741         public function isQuotedIdentifier( $name ) {
2742                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2743         }
2744
2745         /**
2746          * @param string $s
2747          * @return string
2748          */
2749         protected function escapeLikeInternal( $s ) {
2750                 return addcslashes( $s, '\%_' );
2751         }
2752
2753         /**
2754          * LIKE statement wrapper, receives a variable-length argument list with
2755          * parts of pattern to match containing either string literals that will be
2756          * escaped or tokens returned by anyChar() or anyString(). Alternatively,
2757          * the function could be provided with an array of aforementioned
2758          * parameters.
2759          *
2760          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
2761          * a LIKE clause that searches for subpages of 'My page title'.
2762          * Alternatively:
2763          *   $pattern = array( 'My_page_title/', $dbr->anyString() );
2764          *   $query .= $dbr->buildLike( $pattern );
2765          *
2766          * @since 1.16
2767          * @return string Fully built LIKE statement
2768          */
2769         public function buildLike() {
2770                 $params = func_get_args();
2771
2772                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2773                         $params = $params[0];
2774                 }
2775
2776                 $s = '';
2777
2778                 foreach ( $params as $value ) {
2779                         if ( $value instanceof LikeMatch ) {
2780                                 $s .= $value->toString();
2781                         } else {
2782                                 $s .= $this->escapeLikeInternal( $value );
2783                         }
2784                 }
2785
2786                 return " LIKE {$this->addQuotes( $s )} ";
2787         }
2788
2789         /**
2790          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2791          *
2792          * @return LikeMatch
2793          */
2794         public function anyChar() {
2795                 return new LikeMatch( '_' );
2796         }
2797
2798         /**
2799          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2800          *
2801          * @return LikeMatch
2802          */
2803         public function anyString() {
2804                 return new LikeMatch( '%' );
2805         }
2806
2807         /**
2808          * Returns an appropriately quoted sequence value for inserting a new row.
2809          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2810          * subclass will return an integer, and save the value for insertId()
2811          *
2812          * Any implementation of this function should *not* involve reusing
2813          * sequence numbers created for rolled-back transactions.
2814          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2815          * @param string $seqName
2816          * @return null|int
2817          */
2818         public function nextSequenceValue( $seqName ) {
2819                 return null;
2820         }
2821
2822         /**
2823          * USE INDEX clause. Unlikely to be useful for anything but MySQL. This
2824          * is only needed because a) MySQL must be as efficient as possible due to
2825          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2826          * which index to pick. Anyway, other databases might have different
2827          * indexes on a given table. So don't bother overriding this unless you're
2828          * MySQL.
2829          * @param string $index
2830          * @return string
2831          */
2832         public function useIndexClause( $index ) {
2833                 return '';
2834         }
2835
2836         /**
2837          * REPLACE query wrapper.
2838          *
2839          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2840          * except that when there is a duplicate key error, the old row is deleted
2841          * and the new row is inserted in its place.
2842          *
2843          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2844          * perform the delete, we need to know what the unique indexes are so that
2845          * we know how to find the conflicting rows.
2846          *
2847          * It may be more efficient to leave off unique indexes which are unlikely
2848          * to collide. However if you do this, you run the risk of encountering
2849          * errors which wouldn't have occurred in MySQL.
2850          *
2851          * @param string $table The table to replace the row(s) in.
2852          * @param array $uniqueIndexes Is an array of indexes. Each element may be either
2853          *    a field name or an array of field names
2854          * @param array $rows Can be either a single row to insert, or multiple rows,
2855          *    in the same format as for DatabaseBase::insert()
2856          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2857          */
2858         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2859                 $quotedTable = $this->tableName( $table );
2860
2861                 if ( count( $rows ) == 0 ) {
2862                         return;
2863                 }
2864
2865                 # Single row case
2866                 if ( !is_array( reset( $rows ) ) ) {
2867                         $rows = array( $rows );
2868                 }
2869
2870                 foreach ( $rows as $row ) {
2871                         # Delete rows which collide
2872                         if ( $uniqueIndexes ) {
2873                                 $sql = "DELETE FROM $quotedTable WHERE ";
2874                                 $first = true;
2875                                 foreach ( $uniqueIndexes as $index ) {
2876                                         if ( $first ) {
2877                                                 $first = false;
2878                                                 $sql .= '( ';
2879                                         } else {
2880                                                 $sql .= ' ) OR ( ';
2881                                         }
2882                                         if ( is_array( $index ) ) {
2883                                                 $first2 = true;
2884                                                 foreach ( $index as $col ) {
2885                                                         if ( $first2 ) {
2886                                                                 $first2 = false;
2887                                                         } else {
2888                                                                 $sql .= ' AND ';
2889                                                         }
2890                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2891                                                 }
2892                                         } else {
2893                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2894                                         }
2895                                 }
2896                                 $sql .= ' )';
2897                                 $this->query( $sql, $fname );
2898                         }
2899
2900                         # Now insert the row
2901                         $this->insert( $table, $row, $fname );
2902                 }
2903         }
2904
2905         /**
2906          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2907          * statement.
2908          *
2909          * @param string $table Table name
2910          * @param array|string $rows Row(s) to insert
2911          * @param string $fname Caller function name
2912          *
2913          * @return ResultWrapper
2914          */
2915         protected function nativeReplace( $table, $rows, $fname ) {
2916                 $table = $this->tableName( $table );
2917
2918                 # Single row case
2919                 if ( !is_array( reset( $rows ) ) ) {
2920                         $rows = array( $rows );
2921                 }
2922
2923                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2924                 $first = true;
2925
2926                 foreach ( $rows as $row ) {
2927                         if ( $first ) {
2928                                 $first = false;
2929                         } else {
2930                                 $sql .= ',';
2931                         }
2932
2933                         $sql .= '(' . $this->makeList( $row ) . ')';
2934                 }
2935
2936                 return $this->query( $sql, $fname );
2937         }
2938
2939         /**
2940          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
2941          *
2942          * This updates any conflicting rows (according to the unique indexes) using
2943          * the provided SET clause and inserts any remaining (non-conflicted) rows.
2944          *
2945          * $rows may be either:
2946          *   - A single associative array. The array keys are the field names, and
2947          *     the values are the values to insert. The values are treated as data
2948          *     and will be quoted appropriately. If NULL is inserted, this will be
2949          *     converted to a database NULL.
2950          *   - An array with numeric keys, holding a list of associative arrays.
2951          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2952          *     each subarray must be identical to each other, and in the same order.
2953          *
2954          * It may be more efficient to leave off unique indexes which are unlikely
2955          * to collide. However if you do this, you run the risk of encountering
2956          * errors which wouldn't have occurred in MySQL.
2957          *
2958          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2959          * returns success.
2960          *
2961          * @since 1.22
2962          *
2963          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
2964          * @param array $rows A single row or list of rows to insert
2965          * @param array $uniqueIndexes List of single field names or field name tuples
2966          * @param array $set An array of values to SET. For each array element, the
2967          *   key gives the field name, and the value gives the data to set that
2968          *   field to. The data will be quoted by DatabaseBase::addQuotes().
2969          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2970          * @throws Exception
2971          * @return bool
2972          */
2973         public function upsert( $table, array $rows, array $uniqueIndexes, array $set,
2974                 $fname = __METHOD__
2975         ) {
2976                 if ( !count( $rows ) ) {
2977                         return true; // nothing to do
2978                 }
2979
2980                 if ( !is_array( reset( $rows ) ) ) {
2981                         $rows = array( $rows );
2982                 }
2983
2984                 if ( count( $uniqueIndexes ) ) {
2985                         $clauses = array(); // list WHERE clauses that each identify a single row
2986                         foreach ( $rows as $row ) {
2987                                 foreach ( $uniqueIndexes as $index ) {
2988                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2989                                         $rowKey = array(); // unique key to this row
2990                                         foreach ( $index as $column ) {
2991                                                 $rowKey[$column] = $row[$column];
2992                                         }
2993                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2994                                 }
2995                         }
2996                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2997                 } else {
2998                         $where = false;
2999                 }
3000
3001                 $useTrx = !$this->mTrxLevel;
3002                 if ( $useTrx ) {
3003                         $this->begin( $fname );
3004                 }
3005                 try {
3006                         # Update any existing conflicting row(s)
3007                         if ( $where !== false ) {
3008                                 $ok = $this->update( $table, $set, $where, $fname );
3009                         } else {
3010                                 $ok = true;
3011                         }
3012                         # Now insert any non-conflicting row(s)
3013                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
3014                 } catch ( Exception $e ) {
3015                         if ( $useTrx ) {
3016                                 $this->rollback( $fname );
3017                         }
3018                         throw $e;
3019                 }
3020                 if ( $useTrx ) {
3021                         $this->commit( $fname );
3022                 }
3023
3024                 return $ok;
3025         }
3026
3027         /**
3028          * DELETE where the condition is a join.
3029          *
3030          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
3031          * we use sub-selects
3032          *
3033          * For safety, an empty $conds will not delete everything. If you want to
3034          * delete all rows where the join condition matches, set $conds='*'.
3035          *
3036          * DO NOT put the join condition in $conds.
3037          *
3038          * @param string $delTable The table to delete from.
3039          * @param string $joinTable The other table.
3040          * @param string $delVar The variable to join on, in the first table.
3041          * @param string $joinVar The variable to join on, in the second table.
3042          * @param array $conds Condition array of field names mapped to variables,
3043          *   ANDed together in the WHERE clause
3044          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
3045          * @throws DBUnexpectedError
3046          */
3047         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
3048                 $fname = __METHOD__
3049         ) {
3050                 if ( !$conds ) {
3051                         throw new DBUnexpectedError( $this,
3052                                 'DatabaseBase::deleteJoin() called with empty $conds' );
3053                 }
3054
3055                 $delTable = $this->tableName( $delTable );
3056                 $joinTable = $this->tableName( $joinTable );
3057                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
3058                 if ( $conds != '*' ) {
3059                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
3060                 }
3061                 $sql .= ')';
3062
3063                 $this->query( $sql, $fname );
3064         }
3065
3066         /**
3067          * Returns the size of a text field, or -1 for "unlimited"
3068          *
3069          * @param string $table
3070          * @param string $field
3071          * @return int
3072          */
3073         public function textFieldSize( $table, $field ) {
3074                 $table = $this->tableName( $table );
3075                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
3076                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
3077                 $row = $this->fetchObject( $res );
3078
3079                 $m = array();
3080
3081                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
3082                         $size = $m[1];
3083                 } else {
3084                         $size = -1;
3085                 }
3086
3087                 return $size;
3088         }
3089
3090         /**
3091          * A string to insert into queries to show that they're low-priority, like
3092          * MySQL's LOW_PRIORITY. If no such feature exists, return an empty
3093          * string and nothing bad should happen.
3094          *
3095          * @return string Returns the text of the low priority option if it is
3096          *   supported, or a blank string otherwise
3097          */
3098         public function lowPriorityOption() {
3099                 return '';
3100         }
3101
3102         /**
3103          * DELETE query wrapper.
3104          *
3105          * @param array $table Table name
3106          * @param string|array $conds Array of conditions. See $conds in DatabaseBase::select()
3107          *   for the format. Use $conds == "*" to delete all rows
3108          * @param string $fname Name of the calling function
3109          * @throws DBUnexpectedError
3110          * @return bool|ResultWrapper
3111          */
3112         public function delete( $table, $conds, $fname = __METHOD__ ) {
3113                 if ( !$conds ) {
3114                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
3115                 }
3116
3117                 $table = $this->tableName( $table );
3118                 $sql = "DELETE FROM $table";
3119
3120                 if ( $conds != '*' ) {
3121                         if ( is_array( $conds ) ) {
3122                                 $conds = $this->makeList( $conds, LIST_AND );
3123                         }
3124                         $sql .= ' WHERE ' . $conds;
3125                 }
3126
3127                 return $this->query( $sql, $fname );
3128         }
3129
3130         /**
3131          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
3132          * into another table.
3133          *
3134          * @param string $destTable The table name to insert into
3135          * @param string|array $srcTable May be either a table name, or an array of table names
3136          *    to include in a join.
3137          *
3138          * @param array $varMap Must be an associative array of the form
3139          *    array( 'dest1' => 'source1', ...). Source items may be literals
3140          *    rather than field names, but strings should be quoted with
3141          *    DatabaseBase::addQuotes()
3142          *
3143          * @param array $conds Condition array. See $conds in DatabaseBase::select() for
3144          *    the details of the format of condition arrays. May be "*" to copy the
3145          *    whole table.
3146          *
3147          * @param string $fname The function name of the caller, from __METHOD__
3148          *
3149          * @param array $insertOptions Options for the INSERT part of the query, see
3150          *    DatabaseBase::insert() for details.
3151          * @param array $selectOptions Options for the SELECT part of the query, see
3152          *    DatabaseBase::select() for details.
3153          *
3154          * @return ResultWrapper
3155          */
3156         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
3157                 $fname = __METHOD__,
3158                 $insertOptions = array(), $selectOptions = array()
3159         ) {
3160                 $destTable = $this->tableName( $destTable );
3161
3162                 if ( !is_array( $insertOptions ) ) {
3163                         $insertOptions = array( $insertOptions );
3164                 }
3165
3166                 $insertOptions = $this->makeInsertOptions( $insertOptions );
3167
3168                 if ( !is_array( $selectOptions ) ) {
3169                         $selectOptions = array( $selectOptions );
3170                 }
3171
3172                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
3173
3174                 if ( is_array( $srcTable ) ) {
3175                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
3176                 } else {
3177                         $srcTable = $this->tableName( $srcTable );
3178                 }
3179
3180                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
3181                         " SELECT $startOpts " . implode( ',', $varMap ) .
3182                         " FROM $srcTable $useIndex ";
3183
3184                 if ( $conds != '*' ) {
3185                         if ( is_array( $conds ) ) {
3186                                 $conds = $this->makeList( $conds, LIST_AND );
3187                         }
3188                         $sql .= " WHERE $conds";
3189                 }
3190
3191                 $sql .= " $tailOpts";
3192
3193                 return $this->query( $sql, $fname );
3194         }
3195
3196         /**
3197          * Construct a LIMIT query with optional offset. This is used for query
3198          * pages. The SQL should be adjusted so that only the first $limit rows
3199          * are returned. If $offset is provided as well, then the first $offset
3200          * rows should be discarded, and the next $limit rows should be returned.
3201          * If the result of the query is not ordered, then the rows to be returned
3202          * are theoretically arbitrary.
3203          *
3204          * $sql is expected to be a SELECT, if that makes a difference.
3205          *
3206          * The version provided by default works in MySQL and SQLite. It will very
3207          * likely need to be overridden for most other DBMSes.
3208          *
3209          * @param string $sql SQL query we will append the limit too
3210          * @param int $limit The SQL limit
3211          * @param int|bool $offset The SQL offset (default false)
3212          * @throws DBUnexpectedError
3213          * @return string
3214          */
3215         public function limitResult( $sql, $limit, $offset = false ) {
3216                 if ( !is_numeric( $limit ) ) {
3217                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
3218                 }
3219
3220                 return "$sql LIMIT "
3221                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
3222                         . "{$limit} ";
3223         }
3224
3225         /**
3226          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
3227          * within the UNION construct.
3228          * @return bool
3229          */
3230         public function unionSupportsOrderAndLimit() {
3231                 return true; // True for almost every DB supported
3232         }
3233
3234         /**
3235          * Construct a UNION query
3236          * This is used for providing overload point for other DB abstractions
3237          * not compatible with the MySQL syntax.
3238          * @param array $sqls SQL statements to combine
3239          * @param bool $all Use UNION ALL
3240          * @return string SQL fragment
3241          */
3242         public function unionQueries( $sqls, $all ) {
3243                 $glue = $all ? ') UNION ALL (' : ') UNION (';
3244
3245                 return '(' . implode( $glue, $sqls ) . ')';
3246         }
3247
3248         /**
3249          * Returns an SQL expression for a simple conditional. This doesn't need
3250          * to be overridden unless CASE isn't supported in your DBMS.
3251          *
3252          * @param string|array $cond SQL expression which will result in a boolean value
3253          * @param string $trueVal SQL expression to return if true
3254          * @param string $falseVal SQL expression to return if false
3255          * @return string SQL fragment
3256          */
3257         public function conditional( $cond, $trueVal, $falseVal ) {
3258                 if ( is_array( $cond ) ) {
3259                         $cond = $this->makeList( $cond, LIST_AND );
3260                 }
3261
3262                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
3263         }
3264
3265         /**
3266          * Returns a comand for str_replace function in SQL query.
3267          * Uses REPLACE() in MySQL
3268          *
3269          * @param string $orig Column to modify
3270          * @param string $old Column to seek
3271          * @param string $new Column to replace with
3272          *
3273          * @return string
3274          */
3275         public function strreplace( $orig, $old, $new ) {
3276                 return "REPLACE({$orig}, {$old}, {$new})";
3277         }
3278
3279         /**
3280          * Determines how long the server has been up
3281          * STUB
3282          *
3283          * @return int
3284          */
3285         public function getServerUptime() {
3286                 return 0;
3287         }
3288
3289         /**
3290          * Determines if the last failure was due to a deadlock
3291          * STUB
3292          *
3293          * @return bool
3294          */
3295         public function wasDeadlock() {
3296                 return false;
3297         }
3298
3299         /**
3300          * Determines if the last failure was due to a lock timeout
3301          * STUB
3302          *
3303          * @return bool
3304          */
3305         public function wasLockTimeout() {
3306                 return false;
3307         }
3308
3309         /**
3310          * Determines if the last query error was something that should be dealt
3311          * with by pinging the connection and reissuing the query.
3312          * STUB
3313          *
3314          * @return bool
3315          */
3316         public function wasErrorReissuable() {
3317                 return false;
3318         }
3319
3320         /**
3321          * Determines if the last failure was due to the database being read-only.
3322          * STUB
3323          *
3324          * @return bool
3325          */
3326         public function wasReadOnlyError() {
3327                 return false;
3328         }
3329
3330         /**
3331          * Perform a deadlock-prone transaction.
3332          *
3333          * This function invokes a callback function to perform a set of write
3334          * queries. If a deadlock occurs during the processing, the transaction
3335          * will be rolled back and the callback function will be called again.
3336          *
3337          * Usage:
3338          *   $dbw->deadlockLoop( callback, ... );
3339          *
3340          * Extra arguments are passed through to the specified callback function.
3341          *
3342          * Returns whatever the callback function returned on its successful,
3343          * iteration, or false on error, for example if the retry limit was
3344          * reached.
3345          *
3346          * @return bool
3347          */
3348         public function deadlockLoop() {
3349                 $args = func_get_args();
3350                 $function = array_shift( $args );
3351                 $tries = self::DEADLOCK_TRIES;
3352                 if ( is_array( $function ) ) {
3353                         $fname = $function[0];
3354                 } else {
3355                         $fname = $function;
3356                 }
3357
3358                 $this->begin( __METHOD__ );
3359
3360                 $e = null;
3361                 do {
3362                         try {
3363                                 $retVal = call_user_func_array( $function, $args );
3364                                 break;
3365                         } catch ( DBQueryError $e ) {
3366                                 $error = $this->lastError();
3367                                 $errno = $this->lastErrno();
3368                                 $sql = $this->lastQuery();
3369                                 if ( $this->wasDeadlock() ) {
3370                                         // Retry after a randomized delay
3371                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3372                                 } else {
3373                                         // Throw the error back up
3374                                         throw $e;
3375                                 }
3376                         }
3377                 } while ( --$tries > 0 );
3378
3379                 if ( $tries <= 0 ) {
3380                         // Too many deadlocks; give up
3381                         $this->rollback( __METHOD__ );
3382                         throw $e;
3383                 } else {
3384                         $this->commit( __METHOD__ );
3385
3386                         return $retVal;
3387                 }
3388         }
3389
3390         /**
3391          * Wait for the slave to catch up to a given master position.
3392          *
3393          * @param DBMasterPos $pos
3394          * @param int $timeout The maximum number of seconds to wait for
3395          *   synchronisation
3396          * @return int Zero if the slave was past that position already,
3397          *   greater than zero if we waited for some period of time, less than
3398          *   zero if we timed out.
3399          */
3400         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3401                 # Real waits are implemented in the subclass.
3402                 return 0;
3403         }
3404
3405         /**
3406          * Get the replication position of this slave
3407          *
3408          * @return DBMasterPos|bool False if this is not a slave.
3409          */
3410         public function getSlavePos() {
3411                 # Stub
3412                 return false;
3413         }
3414
3415         /**
3416          * Get the position of this master
3417          *
3418          * @return DBMasterPos|bool False if this is not a master
3419          */
3420         public function getMasterPos() {
3421                 # Stub
3422                 return false;
3423         }
3424
3425         /**
3426          * Run an anonymous function as soon as there is no transaction pending.
3427          * If there is a transaction and it is rolled back, then the callback is cancelled.
3428          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
3429          * Callbacks must commit any transactions that they begin.
3430          *
3431          * This is useful for updates to different systems or when separate transactions are needed.
3432          * For example, one might want to enqueue jobs into a system outside the database, but only
3433          * after the database is updated so that the jobs will see the data when they actually run.
3434          * It can also be used for updates that easily cause deadlocks if locks are held too long.
3435          *
3436          * @param callable $callback
3437          * @since 1.20
3438          */
3439         final public function onTransactionIdle( $callback ) {
3440                 $this->mTrxIdleCallbacks[] = array( $callback, wfGetCaller() );
3441                 if ( !$this->mTrxLevel ) {
3442                         $this->runOnTransactionIdleCallbacks();
3443                 }
3444         }
3445
3446         /**
3447          * Run an anonymous function before the current transaction commits or now if there is none.
3448          * If there is a transaction and it is rolled back, then the callback is cancelled.
3449          * Callbacks must not start nor commit any transactions.
3450          *
3451          * This is useful for updates that easily cause deadlocks if locks are held too long
3452          * but where atomicity is strongly desired for these updates and some related updates.
3453          *
3454          * @param callable $callback
3455          * @since 1.22
3456          */
3457         final public function onTransactionPreCommitOrIdle( $callback ) {
3458                 if ( $this->mTrxLevel ) {
3459                         $this->mTrxPreCommitCallbacks[] = array( $callback, wfGetCaller() );
3460                 } else {
3461                         $this->onTransactionIdle( $callback ); // this will trigger immediately
3462                 }
3463         }
3464
3465         /**
3466          * Actually any "on transaction idle" callbacks.
3467          *
3468          * @since 1.20
3469          */
3470         protected function runOnTransactionIdleCallbacks() {
3471                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
3472
3473                 $e = $ePrior = null; // last exception
3474                 do { // callbacks may add callbacks :)
3475                         $callbacks = $this->mTrxIdleCallbacks;
3476                         $this->mTrxIdleCallbacks = array(); // recursion guard
3477                         foreach ( $callbacks as $callback ) {
3478                                 try {
3479                                         list( $phpCallback ) = $callback;
3480                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
3481                                         call_user_func( $phpCallback );
3482                                         $this->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore automatic begin()
3483                                 } catch ( Exception $e ) {
3484                                         if ( $ePrior ) {
3485                                                 MWExceptionHandler::logException( $ePrior );
3486                                         }
3487                                         $ePrior = $e;
3488                                 }
3489                         }
3490                 } while ( count( $this->mTrxIdleCallbacks ) );
3491
3492                 if ( $e instanceof Exception ) {
3493                         throw $e; // re-throw any last exception
3494                 }
3495         }
3496
3497         /**
3498          * Actually any "on transaction pre-commit" callbacks.
3499          *
3500          * @since 1.22
3501          */
3502         protected function runOnTransactionPreCommitCallbacks() {
3503                 $e = $ePrior = null; // last exception
3504                 do { // callbacks may add callbacks :)
3505                         $callbacks = $this->mTrxPreCommitCallbacks;
3506                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
3507                         foreach ( $callbacks as $callback ) {
3508                                 try {
3509                                         list( $phpCallback ) = $callback;
3510                                         call_user_func( $phpCallback );
3511                                 } catch ( Exception $e ) {
3512                                         if ( $ePrior ) {
3513                                                 MWExceptionHandler::logException( $ePrior );
3514                                         }
3515                                         $ePrior = $e;
3516                                 }
3517                         }
3518                 } while ( count( $this->mTrxPreCommitCallbacks ) );
3519
3520                 if ( $e instanceof Exception ) {
3521                         throw $e; // re-throw any last exception
3522                 }
3523         }
3524
3525         /**
3526          * Begin an atomic section of statements
3527          *
3528          * If a transaction has been started already, just keep track of the given
3529          * section name to make sure the transaction is not committed pre-maturely.
3530          * This function can be used in layers (with sub-sections), so use a stack
3531          * to keep track of the different atomic sections. If there is no transaction,
3532          * start one implicitly.
3533          *
3534          * The goal of this function is to create an atomic section of SQL queries
3535          * without having to start a new transaction if it already exists.
3536          *
3537          * Atomic sections are more strict than transactions. With transactions,
3538          * attempting to begin a new transaction when one is already running results
3539          * in MediaWiki issuing a brief warning and doing an implicit commit. All
3540          * atomic levels *must* be explicitly closed using DatabaseBase::endAtomic(),
3541          * and any database transactions cannot be began or committed until all atomic
3542          * levels are closed. There is no such thing as implicitly opening or closing
3543          * an atomic section.
3544          *
3545          * @since 1.23
3546          * @param string $fname
3547          * @throws DBError
3548          */
3549         final public function startAtomic( $fname = __METHOD__ ) {
3550                 if ( !$this->mTrxLevel ) {
3551                         $this->begin( $fname );
3552                         $this->mTrxAutomatic = true;
3553                         // If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
3554                         // in all changes being in one transaction to keep requests transactional.
3555                         if ( !$this->getFlag( DBO_TRX ) ) {
3556                                 $this->mTrxAutomaticAtomic = true;
3557                         }
3558                 }
3559
3560                 $this->mTrxAtomicLevels->push( $fname );
3561         }
3562
3563         /**
3564          * Ends an atomic section of SQL statements
3565          *
3566          * Ends the next section of atomic SQL statements and commits the transaction
3567          * if necessary.
3568          *
3569          * @since 1.23
3570          * @see DatabaseBase::startAtomic
3571          * @param string $fname
3572          * @throws DBError
3573          */
3574         final public function endAtomic( $fname = __METHOD__ ) {
3575                 if ( !$this->mTrxLevel ) {
3576                         throw new DBUnexpectedError( $this, 'No atomic transaction is open.' );
3577                 }
3578                 if ( $this->mTrxAtomicLevels->isEmpty() ||
3579                         $this->mTrxAtomicLevels->pop() !== $fname
3580                 ) {
3581                         throw new DBUnexpectedError( $this, 'Invalid atomic section ended.' );
3582                 }
3583
3584                 if ( $this->mTrxAtomicLevels->isEmpty() && $this->mTrxAutomaticAtomic ) {
3585                         $this->commit( $fname, 'flush' );
3586                 }
3587         }
3588
3589         /**
3590          * Begin a transaction. If a transaction is already in progress,
3591          * that transaction will be committed before the new transaction is started.
3592          *
3593          * Note that when the DBO_TRX flag is set (which is usually the case for web
3594          * requests, but not for maintenance scripts), any previous database query
3595          * will have started a transaction automatically.
3596          *
3597          * Nesting of transactions is not supported. Attempts to nest transactions
3598          * will cause a warning, unless the current transaction was started
3599          * automatically because of the DBO_TRX flag.
3600          *
3601          * @param string $fname
3602          * @throws DBError
3603          */
3604         final public function begin( $fname = __METHOD__ ) {
3605                 global $wgDebugDBTransactions;
3606
3607                 if ( $this->mTrxLevel ) { // implicit commit
3608                         if ( !$this->mTrxAtomicLevels->isEmpty() ) {
3609                                 // If the current transaction was an automatic atomic one, then we definitely have
3610                                 // a problem. Same if there is any unclosed atomic level.
3611                                 throw new DBUnexpectedError( $this,
3612                                         "Attempted to start explicit transaction when atomic levels are still open."
3613                                 );
3614                         } elseif ( !$this->mTrxAutomatic ) {
3615                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
3616                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
3617                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
3618                                         " performing implicit commit!";
3619                                 wfWarn( $msg );
3620                                 wfLogDBError( $msg,
3621                                         $this->getLogContext( array(
3622                                                 'method' => __METHOD__,
3623                                                 'fname' => $fname,
3624                                         ) )
3625                                 );
3626                         } else {
3627                                 // if the transaction was automatic and has done write operations,
3628                                 // log it if $wgDebugDBTransactions is enabled.
3629                                 if ( $this->mTrxDoneWrites && $wgDebugDBTransactions ) {
3630                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
3631                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
3632                                         );
3633                                 }
3634                         }
3635
3636                         $this->runOnTransactionPreCommitCallbacks();
3637                         $this->doCommit( $fname );
3638                         if ( $this->mTrxDoneWrites ) {
3639                                 $this->mDoneWrites = microtime( true );
3640                                 $this->getTransactionProfiler()->transactionWritingOut(
3641                                         $this->mServer, $this->mDBname, $this->mTrxShortId );
3642                         }
3643                         $this->runOnTransactionIdleCallbacks();
3644                 }
3645
3646                 # Avoid fatals if close() was called
3647                 if ( !$this->isOpen() ) {
3648                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
3649                 }
3650
3651                 $this->doBegin( $fname );
3652                 $this->mTrxTimestamp = microtime( true );
3653                 $this->mTrxFname = $fname;
3654                 $this->mTrxDoneWrites = false;
3655                 $this->mTrxAutomatic = false;
3656                 $this->mTrxAutomaticAtomic = false;
3657                 $this->mTrxAtomicLevels = new SplStack;
3658                 $this->mTrxIdleCallbacks = array();
3659                 $this->mTrxPreCommitCallbacks = array();
3660                 $this->mTrxShortId = wfRandomString( 12 );
3661                 $this->mTrxWriteDuration = 0.0;
3662         }
3663
3664         /**
3665          * Issues the BEGIN command to the database server.
3666          *
3667          * @see DatabaseBase::begin()
3668          * @param string $fname
3669          */
3670         protected function doBegin( $fname ) {
3671                 $this->query( 'BEGIN', $fname );
3672                 $this->mTrxLevel = 1;
3673         }
3674
3675         /**
3676          * Commits a transaction previously started using begin().
3677          * If no transaction is in progress, a warning is issued.
3678          *
3679          * Nesting of transactions is not supported.
3680          *
3681          * @param string $fname
3682          * @param string $flush Flush flag, set to 'flush' to disable warnings about
3683          *   explicitly committing implicit transactions, or calling commit when no
3684          *   transaction is in progress. This will silently break any ongoing
3685          *   explicit transaction. Only set the flush flag if you are sure that it
3686          *   is safe to ignore these warnings in your context.
3687          * @throws DBUnexpectedError
3688          */
3689         final public function commit( $fname = __METHOD__, $flush = '' ) {
3690                 if ( !$this->mTrxAtomicLevels->isEmpty() ) {
3691                         // There are still atomic sections open. This cannot be ignored
3692                         throw new DBUnexpectedError(
3693                                 $this,
3694                                 "Attempted to commit transaction while atomic sections are still open"
3695                         );
3696                 }
3697
3698                 if ( $flush === 'flush' ) {
3699                         if ( !$this->mTrxLevel ) {
3700                                 return; // nothing to do
3701                         } elseif ( !$this->mTrxAutomatic ) {
3702                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3703                         }
3704                 } else {
3705                         if ( !$this->mTrxLevel ) {
3706                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
3707                                 return; // nothing to do
3708                         } elseif ( $this->mTrxAutomatic ) {
3709                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
3710                         }
3711                 }
3712
3713                 # Avoid fatals if close() was called
3714                 if ( !$this->isOpen() ) {
3715                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
3716                 }
3717
3718                 $this->runOnTransactionPreCommitCallbacks();
3719                 $this->doCommit( $fname );
3720                 if ( $this->mTrxDoneWrites ) {
3721                         $this->mDoneWrites = microtime( true );
3722                         $this->getTransactionProfiler()->transactionWritingOut(
3723                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3724                 }
3725                 $this->runOnTransactionIdleCallbacks();
3726         }
3727
3728         /**
3729          * Issues the COMMIT command to the database server.
3730          *
3731          * @see DatabaseBase::commit()
3732          * @param string $fname
3733          */
3734         protected function doCommit( $fname ) {
3735                 if ( $this->mTrxLevel ) {
3736                         $this->query( 'COMMIT', $fname );
3737                         $this->mTrxLevel = 0;
3738                 }
3739         }
3740
3741         /**
3742          * Rollback a transaction previously started using begin().
3743          * If no transaction is in progress, a warning is issued.
3744          *
3745          * No-op on non-transactional databases.
3746          *
3747          * @param string $fname
3748          * @param string $flush Flush flag, set to 'flush' to disable warnings about
3749          *   calling rollback when no transaction is in progress. This will silently
3750          *   break any ongoing explicit transaction. Only set the flush flag if you
3751          *   are sure that it is safe to ignore these warnings in your context.
3752          * @throws DBUnexpectedError
3753          * @since 1.23 Added $flush parameter
3754          */
3755         final public function rollback( $fname = __METHOD__, $flush = '' ) {
3756                 if ( $flush !== 'flush' ) {
3757                         if ( !$this->mTrxLevel ) {
3758                                 wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
3759                                 return; // nothing to do
3760                         } elseif ( $this->mTrxAutomatic ) {
3761                                 wfWarn( "$fname: Explicit rollback of implicit transaction. Something may be out of sync!" );
3762                         }
3763                 } else {
3764                         if ( !$this->mTrxLevel ) {
3765                                 return; // nothing to do
3766                         } elseif ( !$this->mTrxAutomatic ) {
3767                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3768                         }
3769                 }
3770
3771                 # Avoid fatals if close() was called
3772                 if ( !$this->isOpen() ) {
3773                         throw new DBUnexpectedError( $this, "DB connection was already closed." );
3774                 }
3775
3776                 $this->doRollback( $fname );
3777                 $this->mTrxIdleCallbacks = array(); // cancel
3778                 $this->mTrxPreCommitCallbacks = array(); // cancel
3779                 $this->mTrxAtomicLevels = new SplStack;
3780                 if ( $this->mTrxDoneWrites ) {
3781                         $this->getTransactionProfiler()->transactionWritingOut(
3782                                 $this->mServer, $this->mDBname, $this->mTrxShortId );
3783                 }
3784         }
3785
3786         /**
3787          * Issues the ROLLBACK command to the database server.
3788          *
3789          * @see DatabaseBase::rollback()
3790          * @param string $fname
3791          */
3792         protected function doRollback( $fname ) {
3793                 if ( $this->mTrxLevel ) {
3794                         $this->query( 'ROLLBACK', $fname, true );
3795                         $this->mTrxLevel = 0;
3796                 }
3797         }
3798
3799         /**
3800          * Creates a new table with structure copied from existing table
3801          * Note that unlike most database abstraction functions, this function does not
3802          * automatically append database prefix, because it works at a lower
3803          * abstraction level.
3804          * The table names passed to this function shall not be quoted (this
3805          * function calls addIdentifierQuotes when needed).
3806          *
3807          * @param string $oldName Name of table whose structure should be copied
3808          * @param string $newName Name of table to be created
3809          * @param bool $temporary Whether the new table should be temporary
3810          * @param string $fname Calling function name
3811          * @throws MWException
3812          * @return bool True if operation was successful
3813          */
3814         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3815                 $fname = __METHOD__
3816         ) {
3817                 throw new MWException(
3818                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3819         }
3820
3821         /**
3822          * List all tables on the database
3823          *
3824          * @param string $prefix Only show tables with this prefix, e.g. mw_
3825          * @param string $fname Calling function name
3826          * @throws MWException
3827          */
3828         function listTables( $prefix = null, $fname = __METHOD__ ) {
3829                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3830         }
3831
3832         /**
3833          * Reset the views process cache set by listViews()
3834          * @since 1.22
3835          */
3836         final public function clearViewsCache() {
3837                 $this->allViews = null;
3838         }
3839
3840         /**
3841          * Lists all the VIEWs in the database
3842          *
3843          * For caching purposes the list of all views should be stored in
3844          * $this->allViews. The process cache can be cleared with clearViewsCache()
3845          *
3846          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3847          * @param string $fname Name of calling function
3848          * @throws MWException
3849          * @since 1.22
3850          */
3851         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3852                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
3853         }
3854
3855         /**
3856          * Differentiates between a TABLE and a VIEW
3857          *
3858          * @param string $name Name of the database-structure to test.
3859          * @throws MWException
3860          * @since 1.22
3861          */
3862         public function isView( $name ) {
3863                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
3864         }
3865
3866         /**
3867          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3868          * to the format used for inserting into timestamp fields in this DBMS.
3869          *
3870          * The result is unquoted, and needs to be passed through addQuotes()
3871          * before it can be included in raw SQL.
3872          *
3873          * @param string|int $ts
3874          *
3875          * @return string
3876          */
3877         public function timestamp( $ts = 0 ) {
3878                 return wfTimestamp( TS_MW, $ts );
3879         }
3880
3881         /**
3882          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3883          * to the format used for inserting into timestamp fields in this DBMS. If
3884          * NULL is input, it is passed through, allowing NULL values to be inserted
3885          * into timestamp fields.
3886          *
3887          * The result is unquoted, and needs to be passed through addQuotes()
3888          * before it can be included in raw SQL.
3889          *
3890          * @param string|int $ts
3891          *
3892          * @return string
3893          */
3894         public function timestampOrNull( $ts = null ) {
3895                 if ( is_null( $ts ) ) {
3896                         return null;
3897                 } else {
3898                         return $this->timestamp( $ts );
3899                 }
3900         }
3901
3902         /**
3903          * Take the result from a query, and wrap it in a ResultWrapper if
3904          * necessary. Boolean values are passed through as is, to indicate success
3905          * of write queries or failure.
3906          *
3907          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3908          * resource, and it was necessary to call this function to convert it to
3909          * a wrapper. Nowadays, raw database objects are never exposed to external
3910          * callers, so this is unnecessary in external code. For compatibility with
3911          * old code, ResultWrapper objects are passed through unaltered.
3912          *
3913          * @param bool|ResultWrapper|resource $result
3914          * @return bool|ResultWrapper
3915          */
3916         public function resultObject( $result ) {
3917                 if ( empty( $result ) ) {
3918                         return false;
3919                 } elseif ( $result instanceof ResultWrapper ) {
3920                         return $result;
3921                 } elseif ( $result === true ) {
3922                         // Successful write query
3923                         return $result;
3924                 } else {
3925                         return new ResultWrapper( $this, $result );
3926                 }
3927         }
3928
3929         /**
3930          * Ping the server and try to reconnect if it there is no connection
3931          *
3932          * @return bool Success or failure
3933          */
3934         public function ping() {
3935                 # Stub. Not essential to override.
3936                 return true;
3937         }
3938
3939         /**
3940          * Get slave lag. Currently supported only by MySQL.
3941          *
3942          * Note that this function will generate a fatal error on many
3943          * installations. Most callers should use LoadBalancer::safeGetLag()
3944          * instead.
3945          *
3946          * @return int Database replication lag in seconds
3947          */
3948         public function getLag() {
3949                 return 0;
3950         }
3951
3952         /**
3953          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3954          *
3955          * @return int
3956          */
3957         function maxListLen() {
3958                 return 0;
3959         }
3960
3961         /**
3962          * Some DBMSs have a special format for inserting into blob fields, they
3963          * don't allow simple quoted strings to be inserted. To insert into such
3964          * a field, pass the data through this function before passing it to
3965          * DatabaseBase::insert().
3966          *
3967          * @param string $b
3968          * @return string
3969          */
3970         public function encodeBlob( $b ) {
3971                 return $b;
3972         }
3973
3974         /**
3975          * Some DBMSs return a special placeholder object representing blob fields
3976          * in result objects. Pass the object through this function to return the
3977          * original string.
3978          *
3979          * @param string|Blob $b
3980          * @return string
3981          */
3982         public function decodeBlob( $b ) {
3983                 if ( $b instanceof Blob ) {
3984                         $b = $b->fetch();
3985                 }
3986                 return $b;
3987         }
3988
3989         /**
3990          * Override database's default behavior. $options include:
3991          *     'connTimeout' : Set the connection timeout value in seconds.
3992          *                     May be useful for very long batch queries such as
3993          *                     full-wiki dumps, where a single query reads out over
3994          *                     hours or days.
3995          *
3996          * @param array $options
3997          * @return void
3998          */
3999         public function setSessionOptions( array $options ) {
4000         }
4001
4002         /**
4003          * Read and execute SQL commands from a file.
4004          *
4005          * Returns true on success, error string or exception on failure (depending
4006          * on object's error ignore settings).
4007          *
4008          * @param string $filename File name to open
4009          * @param bool|callable $lineCallback Optional function called before reading each line
4010          * @param bool|callable $resultCallback Optional function called for each MySQL result
4011          * @param bool|string $fname Calling function name or false if name should be
4012          *   generated dynamically using $filename
4013          * @param bool|callable $inputCallback Optional function called for each
4014          *   complete line sent
4015          * @throws Exception|MWException
4016          * @return bool|string
4017          */
4018         public function sourceFile(
4019                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
4020         ) {
4021                 wfSuppressWarnings();
4022                 $fp = fopen( $filename, 'r' );
4023                 wfRestoreWarnings();
4024
4025                 if ( false === $fp ) {
4026                         throw new MWException( "Could not open \"{$filename}\".\n" );
4027                 }
4028
4029                 if ( !$fname ) {
4030                         $fname = __METHOD__ . "( $filename )";
4031                 }
4032
4033                 try {
4034                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
4035                 } catch ( Exception $e ) {
4036                         fclose( $fp );
4037                         throw $e;
4038                 }
4039
4040                 fclose( $fp );
4041
4042                 return $error;
4043         }
4044
4045         /**
4046          * Get the full path of a patch file. Originally based on archive()
4047          * from updaters.inc. Keep in mind this always returns a patch, as
4048          * it fails back to MySQL if no DB-specific patch can be found
4049          *
4050          * @param string $patch The name of the patch, like patch-something.sql
4051          * @return string Full path to patch file
4052          */
4053         public function patchPath( $patch ) {
4054                 global $IP;
4055
4056                 $dbType = $this->getType();
4057                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
4058                         return "$IP/maintenance/$dbType/archives/$patch";
4059                 } else {
4060                         return "$IP/maintenance/archives/$patch";
4061                 }
4062         }
4063
4064         /**
4065          * Set variables to be used in sourceFile/sourceStream, in preference to the
4066          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
4067          * all. If it's set to false, $GLOBALS will be used.
4068          *
4069          * @param bool|array $vars Mapping variable name to value.
4070          */
4071         public function setSchemaVars( $vars ) {
4072                 $this->mSchemaVars = $vars;
4073         }
4074
4075         /**
4076          * Read and execute commands from an open file handle.
4077          *
4078          * Returns true on success, error string or exception on failure (depending
4079          * on object's error ignore settings).
4080          *
4081          * @param resource $fp File handle
4082          * @param bool|callable $lineCallback Optional function called before reading each query
4083          * @param bool|callable $resultCallback Optional function called for each MySQL result
4084          * @param string $fname Calling function name
4085          * @param bool|callable $inputCallback Optional function called for each complete query sent
4086          * @return bool|string
4087          */
4088         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
4089                 $fname = __METHOD__, $inputCallback = false
4090         ) {
4091                 $cmd = '';
4092
4093                 while ( !feof( $fp ) ) {
4094                         if ( $lineCallback ) {
4095                                 call_user_func( $lineCallback );
4096                         }
4097
4098                         $line = trim( fgets( $fp ) );
4099
4100                         if ( $line == '' ) {
4101                                 continue;
4102                         }
4103
4104                         if ( '-' == $line[0] && '-' == $line[1] ) {
4105                                 continue;
4106                         }
4107
4108                         if ( $cmd != '' ) {
4109                                 $cmd .= ' ';
4110                         }
4111
4112                         $done = $this->streamStatementEnd( $cmd, $line );
4113
4114                         $cmd .= "$line\n";
4115
4116                         if ( $done || feof( $fp ) ) {
4117                                 $cmd = $this->replaceVars( $cmd );
4118
4119                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
4120                                         $res = $this->query( $cmd, $fname );
4121
4122                                         if ( $resultCallback ) {
4123                                                 call_user_func( $resultCallback, $res, $this );
4124                                         }
4125
4126                                         if ( false === $res ) {
4127                                                 $err = $this->lastError();
4128
4129                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
4130                                         }
4131                                 }
4132                                 $cmd = '';
4133                         }
4134                 }
4135
4136                 return true;
4137         }
4138
4139         /**
4140          * Called by sourceStream() to check if we've reached a statement end
4141          *
4142          * @param string $sql SQL assembled so far
4143          * @param string $newLine New line about to be added to $sql
4144          * @return bool Whether $newLine contains end of the statement
4145          */
4146         public function streamStatementEnd( &$sql, &$newLine ) {
4147                 if ( $this->delimiter ) {
4148                         $prev = $newLine;
4149                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
4150                         if ( $newLine != $prev ) {
4151                                 return true;
4152                         }
4153                 }
4154
4155                 return false;
4156         }
4157
4158         /**
4159          * Database independent variable replacement. Replaces a set of variables
4160          * in an SQL statement with their contents as given by $this->getSchemaVars().
4161          *
4162          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
4163          *
4164          * - '{$var}' should be used for text and is passed through the database's
4165          *   addQuotes method.
4166          * - `{$var}` should be used for identifiers (e.g. table and database names).
4167          *   It is passed through the database's addIdentifierQuotes method which
4168          *   can be overridden if the database uses something other than backticks.
4169          * - / *_* / or / *$wgDBprefix* / passes the name that follows through the
4170          *   database's tableName method.
4171          * - / *i* / passes the name that follows through the database's indexName method.
4172          * - In all other cases, / *$var* / is left unencoded. Except for table options,
4173          *   its use should be avoided. In 1.24 and older, string encoding was applied.
4174          *
4175          * @param string $ins SQL statement to replace variables in
4176          * @return string The new SQL statement with variables replaced
4177          */
4178         protected function replaceVars( $ins ) {
4179                 $that = $this;
4180                 $vars = $this->getSchemaVars();
4181                 return preg_replace_callback(
4182                         '!
4183                                 /\* (\$wgDBprefix|[_i]) \*/ (\w*) | # 1-2. tableName, indexName
4184                                 \'\{\$ (\w+) }\'                  | # 3. addQuotes
4185                                 `\{\$ (\w+) }`                    | # 4. addIdentifierQuotes
4186                                 /\*\$ (\w+) \*/                     # 5. leave unencoded
4187                         !x',
4188                         function ( $m ) use ( $that, $vars ) {
4189                                 // Note: Because of <https://bugs.php.net/bug.php?id=51881>,
4190                                 // check for both nonexistent keys *and* the empty string.
4191                                 if ( isset( $m[1] ) && $m[1] !== '' ) {
4192                                         if ( $m[1] === 'i' ) {
4193                                                 return $that->indexName( $m[2] );
4194                                         } else {
4195                                                 return $that->tableName( $m[2] );
4196                                         }
4197                                 } elseif ( isset( $m[3] ) && $m[3] !== '' && array_key_exists( $m[3], $vars ) ) {
4198                                         return $that->addQuotes( $vars[$m[3]] );
4199                                 } elseif ( isset( $m[4] ) && $m[4] !== '' && array_key_exists( $m[4], $vars ) ) {
4200                                         return $that->addIdentifierQuotes( $vars[$m[4]] );
4201                                 } elseif ( isset( $m[5] ) && $m[5] !== '' && array_key_exists( $m[5], $vars ) ) {
4202                                         return $vars[$m[5]];
4203                                 } else {
4204                                         return $m[0];
4205                                 }
4206                         },
4207                         $ins
4208                 );
4209         }
4210
4211         /**
4212          * Get schema variables. If none have been set via setSchemaVars(), then
4213          * use some defaults from the current object.
4214          *
4215          * @return array
4216          */
4217         protected function getSchemaVars() {
4218                 if ( $this->mSchemaVars ) {
4219                         return $this->mSchemaVars;
4220                 } else {
4221                         return $this->getDefaultSchemaVars();
4222                 }
4223         }
4224
4225         /**
4226          * Get schema variables to use if none have been set via setSchemaVars().
4227          *
4228          * Override this in derived classes to provide variables for tables.sql
4229          * and SQL patch files.
4230          *
4231          * @return array
4232          */
4233         protected function getDefaultSchemaVars() {
4234                 return array();
4235         }
4236
4237         /**
4238          * Check to see if a named lock is available. This is non-blocking.
4239          *
4240          * @param string $lockName Name of lock to poll
4241          * @param string $method Name of method calling us
4242          * @return bool
4243          * @since 1.20
4244          */
4245         public function lockIsFree( $lockName, $method ) {
4246                 return true;
4247         }
4248
4249         /**
4250          * Acquire a named lock
4251          *
4252          * Abstracted from Filestore::lock() so child classes can implement for
4253          * their own needs.
4254          *
4255          * @param string $lockName Name of lock to aquire
4256          * @param string $method Name of method calling us
4257          * @param int $timeout
4258          * @return bool
4259          */
4260         public function lock( $lockName, $method, $timeout = 5 ) {
4261                 return true;
4262         }
4263
4264         /**
4265          * Release a lock.
4266          *
4267          * @param string $lockName Name of lock to release
4268          * @param string $method Name of method calling us
4269          *
4270          * @return int Returns 1 if the lock was released, 0 if the lock was not established
4271          * by this thread (in which case the lock is not released), and NULL if the named
4272          * lock did not exist
4273          */
4274         public function unlock( $lockName, $method ) {
4275                 return true;
4276         }
4277
4278         /**
4279          * Lock specific tables
4280          *
4281          * @param array $read Array of tables to lock for read access
4282          * @param array $write Array of tables to lock for write access
4283          * @param string $method Name of caller
4284          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
4285          * @return bool
4286          */
4287         public function lockTables( $read, $write, $method, $lowPriority = true ) {
4288                 return true;
4289         }
4290
4291         /**
4292          * Unlock specific tables
4293          *
4294          * @param string $method The caller
4295          * @return bool
4296          */
4297         public function unlockTables( $method ) {
4298                 return true;
4299         }
4300
4301         /**
4302          * Delete a table
4303          * @param string $tableName
4304          * @param string $fName
4305          * @return bool|ResultWrapper
4306          * @since 1.18
4307          */
4308         public function dropTable( $tableName, $fName = __METHOD__ ) {
4309                 if ( !$this->tableExists( $tableName, $fName ) ) {
4310                         return false;
4311                 }
4312                 $sql = "DROP TABLE " . $this->tableName( $tableName );
4313                 if ( $this->cascadingDeletes() ) {
4314                         $sql .= " CASCADE";
4315                 }
4316
4317                 return $this->query( $sql, $fName );
4318         }
4319
4320         /**
4321          * Get search engine class. All subclasses of this need to implement this
4322          * if they wish to use searching.
4323          *
4324          * @return string
4325          */
4326         public function getSearchEngine() {
4327                 return 'SearchEngineDummy';
4328         }
4329
4330         /**
4331          * Find out when 'infinity' is. Most DBMSes support this. This is a special
4332          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
4333          * because "i" sorts after all numbers.
4334          *
4335          * @return string
4336          */
4337         public function getInfinity() {
4338                 return 'infinity';
4339         }
4340
4341         /**
4342          * Encode an expiry time into the DBMS dependent format
4343          *
4344          * @param string $expiry Timestamp for expiry, or the 'infinity' string
4345          * @return string
4346          */
4347         public function encodeExpiry( $expiry ) {
4348                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4349                         ? $this->getInfinity()
4350                         : $this->timestamp( $expiry );
4351         }
4352
4353         /**
4354          * Decode an expiry time into a DBMS independent format
4355          *
4356          * @param string $expiry DB timestamp field value for expiry
4357          * @param int $format TS_* constant, defaults to TS_MW
4358          * @return string
4359          */
4360         public function decodeExpiry( $expiry, $format = TS_MW ) {
4361                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4362                         ? 'infinity'
4363                         : wfTimestamp( $format, $expiry );
4364         }
4365
4366         /**
4367          * Allow or deny "big selects" for this session only. This is done by setting
4368          * the sql_big_selects session variable.
4369          *
4370          * This is a MySQL-specific feature.
4371          *
4372          * @param bool|string $value True for allow, false for deny, or "default" to
4373          *   restore the initial value
4374          */
4375         public function setBigSelects( $value = true ) {
4376                 // no-op
4377         }
4378
4379         /**
4380          * @since 1.19
4381          * @return string
4382          */
4383         public function __toString() {
4384                 return (string)$this->mConn;
4385         }
4386
4387         /**
4388          * Run a few simple sanity checks
4389          */
4390         public function __destruct() {
4391                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
4392                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
4393                 }
4394                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
4395                         $callers = array();
4396                         foreach ( $this->mTrxIdleCallbacks as $callbackInfo ) {
4397                                 $callers[] = $callbackInfo[1];
4398                         }
4399                         $callers = implode( ', ', $callers );
4400                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
4401                 }
4402         }
4403 }