includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26
  27 /**
  28  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  29  * following must be implemented to support MediaWiki
  30  *
  31  * @file
  32  * @ingroup Database
  33  */
  34 interface DatabaseType {
  35         /**
  36          * Get the type of the DBMS, as it appears in $wgDBtype.
  37          *
  38          * @return string
  39          */
  40         function getType();
  41
  42         /**
  43          * Open a connection to the database. Usually aborts on failure
  44          *
  45          * @param string $server database server host
  46          * @param string $user database user name
  47          * @param string $password database user password
  48          * @param string $dbName database name
  49          * @return bool
  50          * @throws DBConnectionError
  51          */
  52         function open( $server, $user, $password, $dbName );
  53
  54         /**
  55          * Fetch the next row from the given result object, in object form.
  56          * Fields can be retrieved with $row->fieldname, with fields acting like
  57          * member variables.
  58          * If no more rows are available, false is returned.
  59          *
  60          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  61          * @return object|bool
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         function fetchObject( $res );
  65
  66         /**
  67          * Fetch the next row from the given result object, in associative array
  68          * form.  Fields are retrieved with $row['fieldname'].
  69          * If no more rows are available, false is returned.
  70          *
  71          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  72          * @return array|bool
  73          * @throws DBUnexpectedError Thrown if the database returns an error
  74          */
  75         function fetchRow( $res );
  76
  77         /**
  78          * Get the number of rows in a result object
  79          *
  80          * @param $res Mixed: A SQL result
  81          * @return int
  82          */
  83         function numRows( $res );
  84
  85         /**
  86          * Get the number of fields in a result object
  87          * @see http://www.php.net/mysql_num_fields
  88          *
  89          * @param $res Mixed: A SQL result
  90          * @return int
  91          */
  92         function numFields( $res );
  93
  94         /**
  95          * Get a field name in a result object
  96          * @see http://www.php.net/mysql_field_name
  97          *
  98          * @param $res Mixed: A SQL result
  99          * @param $n Integer
 100          * @return string
 101          */
 102         function fieldName( $res, $n );
 103
 104         /**
 105          * Get the inserted value of an auto-increment row
 106          *
 107          * The value inserted should be fetched from nextSequenceValue()
 108          *
 109          * Example:
 110          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 111          * $dbw->insert( 'page', array( 'page_id' => $id ) );
 112          * $id = $dbw->insertId();
 113          *
 114          * @return int
 115          */
 116         function insertId();
 117
 118         /**
 119          * Change the position of the cursor in a result object
 120          * @see http://www.php.net/mysql_data_seek
 121          *
 122          * @param $res Mixed: A SQL result
 123          * @param $row Mixed: Either MySQL row or ResultWrapper
 124          */
 125         function dataSeek( $res, $row );
 126
 127         /**
 128          * Get the last error number
 129          * @see http://www.php.net/mysql_errno
 130          *
 131          * @return int
 132          */
 133         function lastErrno();
 134
 135         /**
 136          * Get a description of the last error
 137          * @see http://www.php.net/mysql_error
 138          *
 139          * @return string
 140          */
 141         function lastError();
 142
 143         /**
 144          * mysql_fetch_field() wrapper
 145          * Returns false if the field doesn't exist
 146          *
 147          * @param string $table table name
 148          * @param string $field field name
 149          *
 150          * @return Field
 151          */
 152         function fieldInfo( $table, $field );
 153
 154         /**
 155          * Get information about an index into an object
 156          * @param string $table Table name
 157          * @param string $index Index name
 158          * @param string $fname Calling function name
 159          * @return Mixed: Database-specific index description class or false if the index does not exist
 160          */
 161         function indexInfo( $table, $index, $fname = __METHOD__ );
 162
 163         /**
 164          * Get the number of rows affected by the last write query
 165          * @see http://www.php.net/mysql_affected_rows
 166          *
 167          * @return int
 168          */
 169         function affectedRows();
 170
 171         /**
 172          * Wrapper for addslashes()
 173          *
 174          * @param string $s to be slashed.
 175          * @return string: slashed string.
 176          */
 177         function strencode( $s );
 178
 179         /**
 180          * Returns a wikitext link to the DB's website, e.g.,
 181          *     return "[http://www.mysql.com/ MySQL]";
 182          * Should at least contain plain text, if for some reason
 183          * your database has no website.
 184          *
 185          * @return string: wikitext of a link to the server software's web site
 186          */
 187         function getSoftwareLink();
 188
 189         /**
 190          * A string describing the current software version, like from
 191          * mysql_get_server_info().
 192          *
 193          * @return string: Version information from the database server.
 194          */
 195         function getServerVersion();
 196
 197         /**
 198          * A string describing the current software version, and possibly
 199          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 200          * Use getServerVersion() to get machine-friendly information.
 201          *
 202          * @return string: Version information from the database server
 203          */
 204         function getServerInfo();
 205 }
 206
 207 /**
 208  * Database abstraction object
 209  * @ingroup Database
 210  */
 211 abstract class DatabaseBase implements DatabaseType {
 212         /** Number of times to re-try an operation in case of deadlock */
 213         const DEADLOCK_TRIES = 4;
 214         /** Minimum time to wait before retry, in microseconds */
 215         const DEADLOCK_DELAY_MIN = 500000;
 216         /** Maximum time to wait before retry */
 217         const DEADLOCK_DELAY_MAX = 1500000;
 218
 219 # ------------------------------------------------------------------------------
 220 # Variables
 221 # ------------------------------------------------------------------------------
 222
 223         protected $mLastQuery = '';
 224         protected $mDoneWrites = false;
 225         protected $mPHPError = false;
 226
 227         protected $mServer, $mUser, $mPassword, $mDBname;
 228
 229         protected $mConn = null;
 230         protected $mOpened = false;
 231
 232         /** @var callable[] */
 233         protected $mTrxIdleCallbacks = array();
 234         /** @var callable[] */
 235         protected $mTrxPreCommitCallbacks = array();
 236
 237         protected $mTablePrefix;
 238         protected $mFlags;
 239         protected $mTrxLevel = 0;
 240         protected $mErrorCount = 0;
 241         protected $mLBInfo = array();
 242         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 243         protected $mDefaultBigSelects = null;
 244         protected $mSchemaVars = false;
 245
 246         protected $preparedArgs;
 247
 248         protected $htmlErrors;
 249
 250         protected $delimiter = ';';
 251
 252         /**
 253          * Remembers the function name given for starting the most recent transaction via begin().
 254          * Used to provide additional context for error reporting.
 255          *
 256          * @var String
 257          * @see DatabaseBase::mTrxLevel
 258          */
 259         private $mTrxFname = null;
 260
 261         /**
 262          * Record if possible write queries were done in the last transaction started
 263          *
 264          * @var Bool
 265          * @see DatabaseBase::mTrxLevel
 266          */
 267         private $mTrxDoneWrites = false;
 268
 269         /**
 270          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 271          *
 272          * @var Bool
 273          * @see DatabaseBase::mTrxLevel
 274          */
 275         private $mTrxAutomatic = false;
 276
 277         /**
 278          * @since 1.21
 279          * @var file handle for upgrade
 280          */
 281         protected $fileHandle = null;
 282
 283 # ------------------------------------------------------------------------------
 284 # Accessors
 285 # ------------------------------------------------------------------------------
 286         # These optionally set a variable and return the previous state
 287
 288         /**
 289          * A string describing the current software version, and possibly
 290          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 291          * Use getServerVersion() to get machine-friendly information.
 292          *
 293          * @return string: Version information from the database server
 294          */
 295         public function getServerInfo() {
 296                 return $this->getServerVersion();
 297         }
 298
 299         /**
 300          * @return string: command delimiter used by this database engine
 301          */
 302         public function getDelimiter() {
 303                 return $this->delimiter;
 304         }
 305
 306         /**
 307          * Boolean, controls output of large amounts of debug information.
 308          * @param $debug bool|null
 309          *   - true to enable debugging
 310          *   - false to disable debugging
 311          *   - omitted or null to do nothing
 312          *
 313          * @return bool|null previous value of the flag
 314          */
 315         public function debug( $debug = null ) {
 316                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 317         }
 318
 319         /**
 320          * Turns buffering of SQL result sets on (true) or off (false). Default is
 321          * "on".
 322          *
 323          * Unbuffered queries are very troublesome in MySQL:
 324          *
 325          *   - If another query is executed while the first query is being read
 326          *     out, the first query is killed. This means you can't call normal
 327          *     MediaWiki functions while you are reading an unbuffered query result
 328          *     from a normal wfGetDB() connection.
 329          *
 330          *   - Unbuffered queries cause the MySQL server to use large amounts of
 331          *     memory and to hold broad locks which block other queries.
 332          *
 333          * If you want to limit client-side memory, it's almost always better to
 334          * split up queries into batches using a LIMIT clause than to switch off
 335          * buffering.
 336          *
 337          * @param $buffer null|bool
 338          *
 339          * @return null|bool The previous value of the flag
 340          */
 341         public function bufferResults( $buffer = null ) {
 342                 if ( is_null( $buffer ) ) {
 343                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 344                 } else {
 345                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 346                 }
 347         }
 348
 349         /**
 350          * Turns on (false) or off (true) the automatic generation and sending
 351          * of a "we're sorry, but there has been a database error" page on
 352          * database errors. Default is on (false). When turned off, the
 353          * code should use lastErrno() and lastError() to handle the
 354          * situation as appropriate.
 355          *
 356          * @param $ignoreErrors bool|null
 357          *
 358          * @return bool The previous value of the flag.
 359          */
 360         public function ignoreErrors( $ignoreErrors = null ) {
 361                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 362         }
 363
 364         /**
 365          * Gets or sets the current transaction level.
 366          *
 367          * Historically, transactions were allowed to be "nested". This is no
 368          * longer supported, so this function really only returns a boolean.
 369          *
 370          * @param int $level An integer (0 or 1), or omitted to leave it unchanged.
 371          * @return int The previous value
 372          */
 373         public function trxLevel( $level = null ) {
 374                 return wfSetVar( $this->mTrxLevel, $level );
 375         }
 376
 377         /**
 378          * Get/set the number of errors logged. Only useful when errors are ignored
 379          * @param int $count The count to set, or omitted to leave it unchanged.
 380          * @return int The error count
 381          */
 382         public function errorCount( $count = null ) {
 383                 return wfSetVar( $this->mErrorCount, $count );
 384         }
 385
 386         /**
 387          * Get/set the table prefix.
 388          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 389          * @return string The previous table prefix.
 390          */
 391         public function tablePrefix( $prefix = null ) {
 392                 return wfSetVar( $this->mTablePrefix, $prefix );
 393         }
 394
 395         /**
 396          * Set the filehandle to copy write statements to.
 397          *
 398          * @param $fh filehandle
 399          */
 400         public function setFileHandle( $fh ) {
 401                 $this->fileHandle = $fh;
 402         }
 403
 404         /**
 405          * Get properties passed down from the server info array of the load
 406          * balancer.
 407          *
 408          * @param string $name The entry of the info array to get, or null to get the
 409          *   whole array
 410          *
 411          * @return LoadBalancer|null
 412          */
 413         public function getLBInfo( $name = null ) {
 414                 if ( is_null( $name ) ) {
 415                         return $this->mLBInfo;
 416                 } else {
 417                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 418                                 return $this->mLBInfo[$name];
 419                         } else {
 420                                 return null;
 421                         }
 422                 }
 423         }
 424
 425         /**
 426          * Set the LB info array, or a member of it. If called with one parameter,
 427          * the LB info array is set to that parameter. If it is called with two
 428          * parameters, the member with the given name is set to the given value.
 429          *
 430          * @param $name
 431          * @param $value
 432          */
 433         public function setLBInfo( $name, $value = null ) {
 434                 if ( is_null( $value ) ) {
 435                         $this->mLBInfo = $name;
 436                 } else {
 437                         $this->mLBInfo[$name] = $value;
 438                 }
 439         }
 440
 441         /**
 442          * Set lag time in seconds for a fake slave
 443          *
 444          * @param $lag int
 445          */
 446         public function setFakeSlaveLag( $lag ) {
 447                 $this->mFakeSlaveLag = $lag;
 448         }
 449
 450         /**
 451          * Make this connection a fake master
 452          *
 453          * @param $enabled bool
 454          */
 455         public function setFakeMaster( $enabled = true ) {
 456                 $this->mFakeMaster = $enabled;
 457         }
 458
 459         /**
 460          * Returns true if this database supports (and uses) cascading deletes
 461          *
 462          * @return bool
 463          */
 464         public function cascadingDeletes() {
 465                 return false;
 466         }
 467
 468         /**
 469          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 470          *
 471          * @return bool
 472          */
 473         public function cleanupTriggers() {
 474                 return false;
 475         }
 476
 477         /**
 478          * Returns true if this database is strict about what can be put into an IP field.
 479          * Specifically, it uses a NULL value instead of an empty string.
 480          *
 481          * @return bool
 482          */
 483         public function strictIPs() {
 484                 return false;
 485         }
 486
 487         /**
 488          * Returns true if this database uses timestamps rather than integers
 489          *
 490          * @return bool
 491          */
 492         public function realTimestamps() {
 493                 return false;
 494         }
 495
 496         /**
 497          * Returns true if this database does an implicit sort when doing GROUP BY
 498          *
 499          * @return bool
 500          */
 501         public function implicitGroupby() {
 502                 return true;
 503         }
 504
 505         /**
 506          * Returns true if this database does an implicit order by when the column has an index
 507          * For example: SELECT page_title FROM page LIMIT 1
 508          *
 509          * @return bool
 510          */
 511         public function implicitOrderby() {
 512                 return true;
 513         }
 514
 515         /**
 516          * Returns true if this database can do a native search on IP columns
 517          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 518          *
 519          * @return bool
 520          */
 521         public function searchableIPs() {
 522                 return false;
 523         }
 524
 525         /**
 526          * Returns true if this database can use functional indexes
 527          *
 528          * @return bool
 529          */
 530         public function functionalIndexes() {
 531                 return false;
 532         }
 533
 534         /**
 535          * Return the last query that went through DatabaseBase::query()
 536          * @return String
 537          */
 538         public function lastQuery() {
 539                 return $this->mLastQuery;
 540         }
 541
 542         /**
 543          * Returns true if the connection may have been used for write queries.
 544          * Should return true if unsure.
 545          *
 546          * @return bool
 547          */
 548         public function doneWrites() {
 549                 return $this->mDoneWrites;
 550         }
 551
 552         /**
 553          * Returns true if there is a transaction open with possible write
 554          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 555          *
 556          * @return bool
 557          */
 558         public function writesOrCallbacksPending() {
 559                 return $this->mTrxLevel && (
 560                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 561                 );
 562         }
 563
 564         /**
 565          * Is a connection to the database open?
 566          * @return Boolean
 567          */
 568         public function isOpen() {
 569                 return $this->mOpened;
 570         }
 571
 572         /**
 573          * Set a flag for this connection
 574          *
 575          * @param $flag Integer: DBO_* constants from Defines.php:
 576          *   - DBO_DEBUG: output some debug info (same as debug())
 577          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 578          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 579          *   - DBO_TRX: automatically start transactions
 580          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 581          *       and removes it in command line mode
 582          *   - DBO_PERSISTENT: use persistant database connection
 583          */
 584         public function setFlag( $flag ) {
 585                 global $wgDebugDBTransactions;
 586                 $this->mFlags |= $flag;
 587                 if ( ( $flag & DBO_TRX ) & $wgDebugDBTransactions ) {
 588                         wfDebug( "Implicit transactions are now  disabled.\n" );
 589                 }
 590         }
 591
 592         /**
 593          * Clear a flag for this connection
 594          *
 595          * @param $flag: same as setFlag()'s $flag param
 596          */
 597         public function clearFlag( $flag ) {
 598                 global $wgDebugDBTransactions;
 599                 $this->mFlags &= ~$flag;
 600                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 601                         wfDebug( "Implicit transactions are now disabled.\n" );
 602                 }
 603         }
 604
 605         /**
 606          * Returns a boolean whether the flag $flag is set for this connection
 607          *
 608          * @param $flag: same as setFlag()'s $flag param
 609          * @return Boolean
 610          */
 611         public function getFlag( $flag ) {
 612                 return !!( $this->mFlags & $flag );
 613         }
 614
 615         /**
 616          * General read-only accessor
 617          *
 618          * @param $name string
 619          *
 620          * @return string
 621          */
 622         public function getProperty( $name ) {
 623                 return $this->$name;
 624         }
 625
 626         /**
 627          * @return string
 628          */
 629         public function getWikiID() {
 630                 if ( $this->mTablePrefix ) {
 631                         return "{$this->mDBname}-{$this->mTablePrefix}";
 632                 } else {
 633                         return $this->mDBname;
 634                 }
 635         }
 636
 637         /**
 638          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 639          *
 640          * @return string
 641          */
 642         public function getSchemaPath() {
 643                 global $IP;
 644                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 645                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 646                 } else {
 647                         return "$IP/maintenance/tables.sql";
 648                 }
 649         }
 650
 651 # ------------------------------------------------------------------------------
 652 # Other functions
 653 # ------------------------------------------------------------------------------
 654
 655         /**
 656          * Constructor.
 657          * @param string $server database server host
 658          * @param string $user database user name
 659          * @param string $password database user password
 660          * @param string $dbName database name
 661          * @param $flags
 662          * @param string $tablePrefix database table prefixes. By default use the prefix gave in LocalSettings.php
 663          */
 664         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 665                 $flags = 0, $tablePrefix = 'get from global'
 666         ) {
 667                 global $wgDBprefix, $wgCommandLineMode, $wgDebugDBTransactions;
 668
 669                 $this->mFlags = $flags;
 670
 671                 if ( $this->mFlags & DBO_DEFAULT ) {
 672                         if ( $wgCommandLineMode ) {
 673                                 $this->mFlags &= ~DBO_TRX;
 674                                 if ( $wgDebugDBTransactions ) {
 675                                         wfDebug( "Implicit transaction open disabled.\n" );
 676                                 }
 677                         } else {
 678                                 $this->mFlags |= DBO_TRX;
 679                                 if ( $wgDebugDBTransactions ) {
 680                                         wfDebug( "Implicit transaction open enabled.\n" );
 681                                 }
 682                         }
 683                 }
 684
 685                 /** Get the default table prefix*/
 686                 if ( $tablePrefix == 'get from global' ) {
 687                         $this->mTablePrefix = $wgDBprefix;
 688                 } else {
 689                         $this->mTablePrefix = $tablePrefix;
 690                 }
 691
 692                 if ( $user ) {
 693                         $this->open( $server, $user, $password, $dbName );
 694                 }
 695         }
 696
 697         /**
 698          * Called by serialize. Throw an exception when DB connection is serialized.
 699          * This causes problems on some database engines because the connection is
 700          * not restored on unserialize.
 701          */
 702         public function __sleep() {
 703                 throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
 704         }
 705
 706         /**
 707          * Given a DB type, construct the name of the appropriate child class of
 708          * DatabaseBase. This is designed to replace all of the manual stuff like:
 709          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 710          * as well as validate against the canonical list of DB types we have
 711          *
 712          * This factory function is mostly useful for when you need to connect to a
 713          * database other than the MediaWiki default (such as for external auth,
 714          * an extension, et cetera). Do not use this to connect to the MediaWiki
 715          * database. Example uses in core:
 716          * @see LoadBalancer::reallyOpenConnection()
 717          * @see ForeignDBRepo::getMasterDB()
 718          * @see WebInstaller_DBConnect::execute()
 719          *
 720          * @since 1.18
 721          *
 722          * @param string $dbType A possible DB type
 723          * @param array $p An array of options to pass to the constructor.
 724          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 725          * @return DatabaseBase subclass or null
 726          */
 727         final public static function factory( $dbType, $p = array() ) {
 728                 $canonicalDBTypes = array(
 729                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql'
 730                 );
 731                 $dbType = strtolower( $dbType );
 732                 $class = 'Database' . ucfirst( $dbType );
 733
 734                 if ( in_array( $dbType, $canonicalDBTypes ) || ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) ) {
 735                         return new $class(
 736                                 isset( $p['host'] ) ? $p['host'] : false,
 737                                 isset( $p['user'] ) ? $p['user'] : false,
 738                                 isset( $p['password'] ) ? $p['password'] : false,
 739                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 740                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 741                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
 742                         );
 743                 } else {
 744                         return null;
 745                 }
 746         }
 747
 748         protected function installErrorHandler() {
 749                 $this->mPHPError = false;
 750                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 751                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 752         }
 753
 754         /**
 755          * @return bool|string
 756          */
 757         protected function restoreErrorHandler() {
 758                 restore_error_handler();
 759                 if ( $this->htmlErrors !== false ) {
 760                         ini_set( 'html_errors', $this->htmlErrors );
 761                 }
 762                 if ( $this->mPHPError ) {
 763                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 764                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 765                         return $error;
 766                 } else {
 767                         return false;
 768                 }
 769         }
 770
 771         /**
 772          * @param $errno
 773          * @param $errstr
 774          * @access private
 775          */
 776         public function connectionErrorHandler( $errno, $errstr ) {
 777                 $this->mPHPError = $errstr;
 778         }
 779
 780         /**
 781          * Closes a database connection.
 782          * if it is open : commits any open transactions
 783          *
 784          * @throws MWException
 785          * @return Bool operation success. true if already closed.
 786          */
 787         public function close() {
 788                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 789                         throw new MWException( "Transaction idle callbacks still pending." );
 790                 }
 791                 $this->mOpened = false;
 792                 if ( $this->mConn ) {
 793                         if ( $this->trxLevel() ) {
 794                                 if ( !$this->mTrxAutomatic ) {
 795                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 796                                                 " performing implicit commit before closing connection!" );
 797                                 }
 798
 799                                 $this->commit( __METHOD__, 'flush' );
 800                         }
 801
 802                         $ret = $this->closeConnection();
 803                         $this->mConn = false;
 804                         return $ret;
 805                 } else {
 806                         return true;
 807                 }
 808         }
 809
 810         /**
 811          * Closes underlying database connection
 812          * @since 1.20
 813          * @return bool: Whether connection was closed successfully
 814          */
 815         abstract protected function closeConnection();
 816
 817         /**
 818          * @param string $error fallback error message, used if none is given by DB
 819          * @throws DBConnectionError
 820          */
 821         function reportConnectionError( $error = 'Unknown error' ) {
 822                 $myError = $this->lastError();
 823                 if ( $myError ) {
 824                         $error = $myError;
 825                 }
 826
 827                 # New method
 828                 throw new DBConnectionError( $this, $error );
 829         }
 830
 831         /**
 832          * The DBMS-dependent part of query()
 833          *
 834          * @param  $sql String: SQL query.
 835          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 836          */
 837         abstract protected function doQuery( $sql );
 838
 839         /**
 840          * Determine whether a query writes to the DB.
 841          * Should return true if unsure.
 842          *
 843          * @param $sql string
 844          *
 845          * @return bool
 846          */
 847         public function isWriteQuery( $sql ) {
 848                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 849         }
 850
 851         /**
 852          * Run an SQL query and return the result. Normally throws a DBQueryError
 853          * on failure. If errors are ignored, returns false instead.
 854          *
 855          * In new code, the query wrappers select(), insert(), update(), delete(),
 856          * etc. should be used where possible, since they give much better DBMS
 857          * independence and automatically quote or validate user input in a variety
 858          * of contexts. This function is generally only useful for queries which are
 859          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 860          * as CREATE TABLE.
 861          *
 862          * However, the query wrappers themselves should call this function.
 863          *
 864          * @param  $sql        String: SQL query
 865          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 866          *     comment (you can use __METHOD__ or add some extra info)
 867          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 868          *     maybe best to catch the exception instead?
 869          * @throws MWException
 870          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 871          *     for a successful read query, or false on failure if $tempIgnore set
 872          */
 873         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 874                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 875                 if ( !Profiler::instance()->isStub() ) {
 876                         # generalizeSQL will probably cut down the query to reasonable
 877                         # logging size most of the time. The substr is really just a sanity check.
 878
 879                         if ( $isMaster ) {
 880                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 881                                 $totalProf = 'DatabaseBase::query-master';
 882                         } else {
 883                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 884                                 $totalProf = 'DatabaseBase::query';
 885                         }
 886
 887                         wfProfileIn( $totalProf );
 888                         wfProfileIn( $queryProf );
 889                 }
 890
 891                 $this->mLastQuery = $sql;
 892                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 893                         # Set a flag indicating that writes have been done
 894                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 895                         $this->mDoneWrites = true;
 896                 }
 897
 898                 # Add a comment for easy SHOW PROCESSLIST interpretation
 899                 global $wgUser;
 900                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 901                         $userName = $wgUser->getName();
 902                         if ( mb_strlen( $userName ) > 15 ) {
 903                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 904                         }
 905                         $userName = str_replace( '/', '', $userName );
 906                 } else {
 907                         $userName = '';
 908                 }
 909
 910                 // Add trace comment to the begin of the sql string, right after the operator.
 911                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 912                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 913
 914                 # If DBO_TRX is set, start a transaction
 915                 if ( ( $this->mFlags & DBO_TRX ) && !$this->mTrxLevel &&
 916                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' )
 917                 {
 918                         # Avoid establishing transactions for SHOW and SET statements too -
 919                         # that would delay transaction initializations to once connection
 920                         # is really used by application
 921                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 922                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 ) {
 923                                 global $wgDebugDBTransactions;
 924                                 if ( $wgDebugDBTransactions ) {
 925                                         wfDebug( "Implicit transaction start.\n" );
 926                                 }
 927                                 $this->begin( __METHOD__ . " ($fname)" );
 928                                 $this->mTrxAutomatic = true;
 929                         }
 930                 }
 931
 932                 # Keep track of whether the transaction has write queries pending
 933                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $this->isWriteQuery( $sql ) ) {
 934                         $this->mTrxDoneWrites = true;
 935                 }
 936
 937                 if ( $this->debug() ) {
 938                         static $cnt = 0;
 939
 940                         $cnt++;
 941                         $sqlx = substr( $commentedSql, 0, 500 );
 942                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 943
 944                         $master = $isMaster ? 'master' : 'slave';
 945                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
 946                 }
 947
 948                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 949
 950                 # Do the query and handle errors
 951                 $ret = $this->doQuery( $commentedSql );
 952
 953                 MWDebug::queryTime( $queryId );
 954
 955                 # Try reconnecting if the connection was lost
 956                 if ( false === $ret && $this->wasErrorReissuable() ) {
 957                         # Transaction is gone, like it or not
 958                         $this->mTrxLevel = 0;
 959                         $this->mTrxIdleCallbacks = array(); // cancel
 960                         $this->mTrxPreCommitCallbacks = array(); // cancel
 961                         wfDebug( "Connection lost, reconnecting...\n" );
 962
 963                         if ( $this->ping() ) {
 964                                 wfDebug( "Reconnected\n" );
 965                                 $sqlx = substr( $commentedSql, 0, 500 );
 966                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 967                                 global $wgRequestTime;
 968                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 969                                 if ( $elapsed < 300 ) {
 970                                         # Not a database error to lose a transaction after a minute or two
 971                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 972                                 }
 973                                 $ret = $this->doQuery( $commentedSql );
 974                         } else {
 975                                 wfDebug( "Failed\n" );
 976                         }
 977                 }
 978
 979                 if ( false === $ret ) {
 980                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 981                 }
 982
 983                 if ( !Profiler::instance()->isStub() ) {
 984                         wfProfileOut( $queryProf );
 985                         wfProfileOut( $totalProf );
 986                 }
 987
 988                 return $this->resultObject( $ret );
 989         }
 990
 991         /**
 992          * Report a query error. Log the error, and if neither the object ignore
 993          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 994          *
 995          * @param $error String
 996          * @param $errno Integer
 997          * @param $sql String
 998          * @param $fname String
 999          * @param $tempIgnore Boolean
1000          * @throws DBQueryError
1001          */
1002         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1003                 # Ignore errors during error handling to avoid infinite recursion
1004                 $ignore = $this->ignoreErrors( true );
1005                 ++$this->mErrorCount;
1006
1007                 if ( $ignore || $tempIgnore ) {
1008                         wfDebug( "SQL ERROR (ignored): $error\n" );
1009                         $this->ignoreErrors( $ignore );
1010                 } else {
1011                         $sql1line = str_replace( "\n", "\\n", $sql );
1012                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
1013                         wfDebug( "SQL ERROR: " . $error . "\n" );
1014                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1015                 }
1016         }
1017
1018         /**
1019          * Intended to be compatible with the PEAR::DB wrapper functions.
1020          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1021          *
1022          * ? = scalar value, quoted as necessary
1023          * ! = raw SQL bit (a function for instance)
1024          * & = filename; reads the file and inserts as a blob
1025          *     (we don't use this though...)
1026          *
1027          * @param $sql string
1028          * @param $func string
1029          *
1030          * @return array
1031          */
1032         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1033                 /* MySQL doesn't support prepared statements (yet), so just
1034                    pack up the query for reference. We'll manually replace
1035                    the bits later. */
1036                 return array( 'query' => $sql, 'func' => $func );
1037         }
1038
1039         /**
1040          * Free a prepared query, generated by prepare().
1041          * @param $prepared
1042          */
1043         protected function freePrepared( $prepared ) {
1044                 /* No-op by default */
1045         }
1046
1047         /**
1048          * Execute a prepared query with the various arguments
1049          * @param string $prepared the prepared sql
1050          * @param $args Mixed: Either an array here, or put scalars as varargs
1051          *
1052          * @return ResultWrapper
1053          */
1054         public function execute( $prepared, $args = null ) {
1055                 if ( !is_array( $args ) ) {
1056                         # Pull the var args
1057                         $args = func_get_args();
1058                         array_shift( $args );
1059                 }
1060
1061                 $sql = $this->fillPrepared( $prepared['query'], $args );
1062
1063                 return $this->query( $sql, $prepared['func'] );
1064         }
1065
1066         /**
1067          * For faking prepared SQL statements on DBs that don't support it directly.
1068          *
1069          * @param string $preparedQuery a 'preparable' SQL statement
1070          * @param array $args of arguments to fill it with
1071          * @return string executable SQL
1072          */
1073         public function fillPrepared( $preparedQuery, $args ) {
1074                 reset( $args );
1075                 $this->preparedArgs =& $args;
1076
1077                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1078                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1079         }
1080
1081         /**
1082          * preg_callback func for fillPrepared()
1083          * The arguments should be in $this->preparedArgs and must not be touched
1084          * while we're doing this.
1085          *
1086          * @param $matches Array
1087          * @throws DBUnexpectedError
1088          * @return String
1089          */
1090         protected function fillPreparedArg( $matches ) {
1091                 switch ( $matches[1] ) {
1092                         case '\\?':
1093                                 return '?';
1094                         case '\\!':
1095                                 return '!';
1096                         case '\\&':
1097                                 return '&';
1098                 }
1099
1100                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1101
1102                 switch ( $matches[1] ) {
1103                         case '?':
1104                                 return $this->addQuotes( $arg );
1105                         case '!':
1106                                 return $arg;
1107                         case '&':
1108                                 # return $this->addQuotes( file_get_contents( $arg ) );
1109                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
1110                         default:
1111                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
1112                 }
1113         }
1114
1115         /**
1116          * Free a result object returned by query() or select(). It's usually not
1117          * necessary to call this, just use unset() or let the variable holding
1118          * the result object go out of scope.
1119          *
1120          * @param $res Mixed: A SQL result
1121          */
1122         public function freeResult( $res ) {
1123         }
1124
1125         /**
1126          * A SELECT wrapper which returns a single field from a single result row.
1127          *
1128          * Usually throws a DBQueryError on failure. If errors are explicitly
1129          * ignored, returns false on failure.
1130          *
1131          * If no result rows are returned from the query, false is returned.
1132          *
1133          * @param string|array $table Table name. See DatabaseBase::select() for details.
1134          * @param string $var The field name to select. This must be a valid SQL
1135          *   fragment: do not use unvalidated user input.
1136          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1137          * @param string $fname The function name of the caller.
1138          * @param string|array $options The query options. See DatabaseBase::select() for details.
1139          *
1140          * @return bool|mixed The value from the field, or false on failure.
1141          */
1142         public function selectField( $table, $var, $cond = '', $fname = __METHOD__,
1143                 $options = array()
1144         ) {
1145                 if ( !is_array( $options ) ) {
1146                         $options = array( $options );
1147                 }
1148
1149                 $options['LIMIT'] = 1;
1150
1151                 $res = $this->select( $table, $var, $cond, $fname, $options );
1152
1153                 if ( $res === false || !$this->numRows( $res ) ) {
1154                         return false;
1155                 }
1156
1157                 $row = $this->fetchRow( $res );
1158
1159                 if ( $row !== false ) {
1160                         return reset( $row );
1161                 } else {
1162                         return false;
1163                 }
1164         }
1165
1166         /**
1167          * Returns an optional USE INDEX clause to go after the table, and a
1168          * string to go at the end of the query.
1169          *
1170          * @param array $options associative array of options to be turned into
1171          *              an SQL query, valid keys are listed in the function.
1172          * @return Array
1173          * @see DatabaseBase::select()
1174          */
1175         public function makeSelectOptions( $options ) {
1176                 $preLimitTail = $postLimitTail = '';
1177                 $startOpts = '';
1178
1179                 $noKeyOptions = array();
1180
1181                 foreach ( $options as $key => $option ) {
1182                         if ( is_numeric( $key ) ) {
1183                                 $noKeyOptions[$option] = true;
1184                         }
1185                 }
1186
1187                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1188
1189                 $preLimitTail .= $this->makeOrderBy( $options );
1190
1191                 // if (isset($options['LIMIT'])) {
1192                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1193                 //              isset($options['OFFSET']) ? $options['OFFSET']
1194                 //              : false);
1195                 // }
1196
1197                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1198                         $postLimitTail .= ' FOR UPDATE';
1199                 }
1200
1201                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1202                         $postLimitTail .= ' LOCK IN SHARE MODE';
1203                 }
1204
1205                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1206                         $startOpts .= 'DISTINCT';
1207                 }
1208
1209                 # Various MySQL extensions
1210                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1211                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1212                 }
1213
1214                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1215                         $startOpts .= ' HIGH_PRIORITY';
1216                 }
1217
1218                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1219                         $startOpts .= ' SQL_BIG_RESULT';
1220                 }
1221
1222                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1223                         $startOpts .= ' SQL_BUFFER_RESULT';
1224                 }
1225
1226                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1227                         $startOpts .= ' SQL_SMALL_RESULT';
1228                 }
1229
1230                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1231                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1232                 }
1233
1234                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1235                         $startOpts .= ' SQL_CACHE';
1236                 }
1237
1238                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1239                         $startOpts .= ' SQL_NO_CACHE';
1240                 }
1241
1242                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1243                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1244                 } else {
1245                         $useIndex = '';
1246                 }
1247
1248                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1249         }
1250
1251         /**
1252          * Returns an optional GROUP BY with an optional HAVING
1253          *
1254          * @param array $options associative array of options
1255          * @return string
1256          * @see DatabaseBase::select()
1257          * @since 1.21
1258          */
1259         public function makeGroupByWithHaving( $options ) {
1260                 $sql = '';
1261                 if ( isset( $options['GROUP BY'] ) ) {
1262                         $gb = is_array( $options['GROUP BY'] )
1263                                 ? implode( ',', $options['GROUP BY'] )
1264                                 : $options['GROUP BY'];
1265                         $sql .= ' GROUP BY ' . $gb;
1266                 }
1267                 if ( isset( $options['HAVING'] ) ) {
1268                         $having = is_array( $options['HAVING'] )
1269                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1270                                 : $options['HAVING'];
1271                         $sql .= ' HAVING ' . $having;
1272                 }
1273                 return $sql;
1274         }
1275
1276         /**
1277          * Returns an optional ORDER BY
1278          *
1279          * @param array $options associative array of options
1280          * @return string
1281          * @see DatabaseBase::select()
1282          * @since 1.21
1283          */
1284         public function makeOrderBy( $options ) {
1285                 if ( isset( $options['ORDER BY'] ) ) {
1286                         $ob = is_array( $options['ORDER BY'] )
1287                                 ? implode( ',', $options['ORDER BY'] )
1288                                 : $options['ORDER BY'];
1289                         return ' ORDER BY ' . $ob;
1290                 }
1291                 return '';
1292         }
1293
1294         /**
1295          * Execute a SELECT query constructed using the various parameters provided.
1296          * See below for full details of the parameters.
1297          *
1298          * @param string|array $table Table name
1299          * @param string|array $vars Field names
1300          * @param string|array $conds Conditions
1301          * @param string $fname Caller function name
1302          * @param array $options Query options
1303          * @param $join_conds Array Join conditions
1304          *
1305          * @param $table string|array
1306          *
1307          * May be either an array of table names, or a single string holding a table
1308          * name. If an array is given, table aliases can be specified, for example:
1309          *
1310          *    array( 'a' => 'user' )
1311          *
1312          * This includes the user table in the query, with the alias "a" available
1313          * for use in field names (e.g. a.user_name).
1314          *
1315          * All of the table names given here are automatically run through
1316          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1317          * added, and various other table name mappings to be performed.
1318          *
1319          *
1320          * @param $vars string|array
1321          *
1322          * May be either a field name or an array of field names. The field names
1323          * can be complete fragments of SQL, for direct inclusion into the SELECT
1324          * query. If an array is given, field aliases can be specified, for example:
1325          *
1326          *   array( 'maxrev' => 'MAX(rev_id)' )
1327          *
1328          * This includes an expression with the alias "maxrev" in the query.
1329          *
1330          * If an expression is given, care must be taken to ensure that it is
1331          * DBMS-independent.
1332          *
1333          *
1334          * @param $conds string|array
1335          *
1336          * May be either a string containing a single condition, or an array of
1337          * conditions. If an array is given, the conditions constructed from each
1338          * element are combined with AND.
1339          *
1340          * Array elements may take one of two forms:
1341          *
1342          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1343          *   - Elements with a string key are interpreted as equality conditions,
1344          *     where the key is the field name.
1345          *     - If the value of such an array element is a scalar (such as a
1346          *       string), it will be treated as data and thus quoted appropriately.
1347          *       If it is null, an IS NULL clause will be added.
1348          *     - If the value is an array, an IN(...) clause will be constructed,
1349          *       such that the field name may match any of the elements in the
1350          *       array. The elements of the array will be quoted.
1351          *
1352          * Note that expressions are often DBMS-dependent in their syntax.
1353          * DBMS-independent wrappers are provided for constructing several types of
1354          * expression commonly used in condition queries. See:
1355          *    - DatabaseBase::buildLike()
1356          *    - DatabaseBase::conditional()
1357          *
1358          *
1359          * @param $options string|array
1360          *
1361          * Optional: Array of query options. Boolean options are specified by
1362          * including them in the array as a string value with a numeric key, for
1363          * example:
1364          *
1365          *    array( 'FOR UPDATE' )
1366          *
1367          * The supported options are:
1368          *
1369          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1370          *     with LIMIT can theoretically be used for paging through a result set,
1371          *     but this is discouraged in MediaWiki for performance reasons.
1372          *
1373          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1374          *     and then the first rows are taken until the limit is reached. LIMIT
1375          *     is applied to a result set after OFFSET.
1376          *
1377          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1378          *     changed until the next COMMIT.
1379          *
1380          *   - DISTINCT: Boolean: return only unique result rows.
1381          *
1382          *   - GROUP BY: May be either an SQL fragment string naming a field or
1383          *     expression to group by, or an array of such SQL fragments.
1384          *
1385          *   - HAVING: May be either an string containing a HAVING clause or an array of
1386          *     conditions building the HAVING clause. If an array is given, the conditions
1387          *     constructed from each element are combined with AND.
1388          *
1389          *   - ORDER BY: May be either an SQL fragment giving a field name or
1390          *     expression to order by, or an array of such SQL fragments.
1391          *
1392          *   - USE INDEX: This may be either a string giving the index name to use
1393          *     for the query, or an array. If it is an associative array, each key
1394          *     gives the table name (or alias), each value gives the index name to
1395          *     use for that table. All strings are SQL fragments and so should be
1396          *     validated by the caller.
1397          *
1398          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1399          *     instead of SELECT.
1400          *
1401          * And also the following boolean MySQL extensions, see the MySQL manual
1402          * for documentation:
1403          *
1404          *    - LOCK IN SHARE MODE
1405          *    - STRAIGHT_JOIN
1406          *    - HIGH_PRIORITY
1407          *    - SQL_BIG_RESULT
1408          *    - SQL_BUFFER_RESULT
1409          *    - SQL_SMALL_RESULT
1410          *    - SQL_CALC_FOUND_ROWS
1411          *    - SQL_CACHE
1412          *    - SQL_NO_CACHE
1413          *
1414          *
1415          * @param $join_conds string|array
1416          *
1417          * Optional associative array of table-specific join conditions. In the
1418          * most common case, this is unnecessary, since the join condition can be
1419          * in $conds. However, it is useful for doing a LEFT JOIN.
1420          *
1421          * The key of the array contains the table name or alias. The value is an
1422          * array with two elements, numbered 0 and 1. The first gives the type of
1423          * join, the second is an SQL fragment giving the join condition for that
1424          * table. For example:
1425          *
1426          *    array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )
1427          *
1428          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1429          *   with no rows in it will be returned. If there was a query error, a
1430          *   DBQueryError exception will be thrown, except if the "ignore errors"
1431          *   option was set, in which case false will be returned.
1432          */
1433         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1434                 $options = array(), $join_conds = array() ) {
1435                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1436
1437                 return $this->query( $sql, $fname );
1438         }
1439
1440         /**
1441          * The equivalent of DatabaseBase::select() except that the constructed SQL
1442          * is returned, instead of being immediately executed. This can be useful for
1443          * doing UNION queries, where the SQL text of each query is needed. In general,
1444          * however, callers outside of Database classes should just use select().
1445          *
1446          * @param string|array $table Table name
1447          * @param string|array $vars Field names
1448          * @param string|array $conds Conditions
1449          * @param string $fname Caller function name
1450          * @param string|array $options Query options
1451          * @param $join_conds string|array Join conditions
1452          *
1453          * @return string SQL query string.
1454          * @see DatabaseBase::select()
1455          */
1456         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1457                 $options = array(), $join_conds = array() )
1458         {
1459                 if ( is_array( $vars ) ) {
1460                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1461                 }
1462
1463                 $options = (array)$options;
1464                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1465                         ? $options['USE INDEX']
1466                         : array();
1467
1468                 if ( is_array( $table ) ) {
1469                         $from = ' FROM ' .
1470                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1471                 } elseif ( $table != '' ) {
1472                         if ( $table[0] == ' ' ) {
1473                                 $from = ' FROM ' . $table;
1474                         } else {
1475                                 $from = ' FROM ' .
1476                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1477                         }
1478                 } else {
1479                         $from = '';
1480                 }
1481
1482                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1483                         $this->makeSelectOptions( $options );
1484
1485                 if ( !empty( $conds ) ) {
1486                         if ( is_array( $conds ) ) {
1487                                 $conds = $this->makeList( $conds, LIST_AND );
1488                         }
1489                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1490                 } else {
1491                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1492                 }
1493
1494                 if ( isset( $options['LIMIT'] ) ) {
1495                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1496                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1497                 }
1498                 $sql = "$sql $postLimitTail";
1499
1500                 if ( isset( $options['EXPLAIN'] ) ) {
1501                         $sql = 'EXPLAIN ' . $sql;
1502                 }
1503
1504                 return $sql;
1505         }
1506
1507         /**
1508          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1509          * that a single row object is returned. If the query returns no rows,
1510          * false is returned.
1511          *
1512          * @param string|array $table Table name
1513          * @param string|array $vars Field names
1514          * @param array $conds Conditions
1515          * @param string $fname Caller function name
1516          * @param string|array $options Query options
1517          * @param $join_conds array|string Join conditions
1518          *
1519          * @return object|bool
1520          */
1521         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1522                 $options = array(), $join_conds = array() )
1523         {
1524                 $options = (array)$options;
1525                 $options['LIMIT'] = 1;
1526                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1527
1528                 if ( $res === false ) {
1529                         return false;
1530                 }
1531
1532                 if ( !$this->numRows( $res ) ) {
1533                         return false;
1534                 }
1535
1536                 $obj = $this->fetchObject( $res );
1537
1538                 return $obj;
1539         }
1540
1541         /**
1542          * Estimate rows in dataset.
1543          *
1544          * MySQL allows you to estimate the number of rows that would be returned
1545          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1546          * index cardinality statistics, and is notoriously inaccurate, especially
1547          * when large numbers of rows have recently been added or deleted.
1548          *
1549          * For DBMSs that don't support fast result size estimation, this function
1550          * will actually perform the SELECT COUNT(*).
1551          *
1552          * Takes the same arguments as DatabaseBase::select().
1553          *
1554          * @param string $table table name
1555          * @param array|string $vars : unused
1556          * @param array|string $conds : filters on the table
1557          * @param string $fname function name for profiling
1558          * @param array $options options for select
1559          * @return Integer: row count
1560          */
1561         public function estimateRowCount( $table, $vars = '*', $conds = '',
1562                 $fname = __METHOD__, $options = array() )
1563         {
1564                 $rows = 0;
1565                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1566
1567                 if ( $res ) {
1568                         $row = $this->fetchRow( $res );
1569                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1570                 }
1571
1572                 return $rows;
1573         }
1574
1575         /**
1576          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1577          * It's only slightly flawed. Don't use for anything important.
1578          *
1579          * @param string $sql A SQL Query
1580          *
1581          * @return string
1582          */
1583         static function generalizeSQL( $sql ) {
1584                 # This does the same as the regexp below would do, but in such a way
1585                 # as to avoid crashing php on some large strings.
1586                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1587
1588                 $sql = str_replace( "\\\\", '', $sql );
1589                 $sql = str_replace( "\\'", '', $sql );
1590                 $sql = str_replace( "\\\"", '', $sql );
1591                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1592                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1593
1594                 # All newlines, tabs, etc replaced by single space
1595                 $sql = preg_replace( '/\s+/', ' ', $sql );
1596
1597                 # All numbers => N
1598                 $sql = preg_replace( '/-?[0-9]+/s', 'N', $sql );
1599
1600                 return $sql;
1601         }
1602
1603         /**
1604          * Determines whether a field exists in a table
1605          *
1606          * @param string $table table name
1607          * @param string $field filed to check on that table
1608          * @param string $fname calling function name (optional)
1609          * @return Boolean: whether $table has filed $field
1610          */
1611         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1612                 $info = $this->fieldInfo( $table, $field );
1613
1614                 return (bool)$info;
1615         }
1616
1617         /**
1618          * Determines whether an index exists
1619          * Usually throws a DBQueryError on failure
1620          * If errors are explicitly ignored, returns NULL on failure
1621          *
1622          * @param $table
1623          * @param $index
1624          * @param $fname string
1625          *
1626          * @return bool|null
1627          */
1628         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1629                 if ( !$this->tableExists( $table ) ) {
1630                         return null;
1631                 }
1632
1633                 $info = $this->indexInfo( $table, $index, $fname );
1634                 if ( is_null( $info ) ) {
1635                         return null;
1636                 } else {
1637                         return $info !== false;
1638                 }
1639         }
1640
1641         /**
1642          * Query whether a given table exists
1643          *
1644          * @param $table string
1645          * @param $fname string
1646          *
1647          * @return bool
1648          */
1649         public function tableExists( $table, $fname = __METHOD__ ) {
1650                 $table = $this->tableName( $table );
1651                 $old = $this->ignoreErrors( true );
1652                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1653                 $this->ignoreErrors( $old );
1654
1655                 return (bool)$res;
1656         }
1657
1658         /**
1659          * mysql_field_type() wrapper
1660          * @param $res
1661          * @param $index
1662          * @return string
1663          */
1664         public function fieldType( $res, $index ) {
1665                 if ( $res instanceof ResultWrapper ) {
1666                         $res = $res->result;
1667                 }
1668
1669                 return mysql_field_type( $res, $index );
1670         }
1671
1672         /**
1673          * Determines if a given index is unique
1674          *
1675          * @param $table string
1676          * @param $index string
1677          *
1678          * @return bool
1679          */
1680         public function indexUnique( $table, $index ) {
1681                 $indexInfo = $this->indexInfo( $table, $index );
1682
1683                 if ( !$indexInfo ) {
1684                         return null;
1685                 }
1686
1687                 return !$indexInfo[0]->Non_unique;
1688         }
1689
1690         /**
1691          * Helper for DatabaseBase::insert().
1692          *
1693          * @param $options array
1694          * @return string
1695          */
1696         protected function makeInsertOptions( $options ) {
1697                 return implode( ' ', $options );
1698         }
1699
1700         /**
1701          * INSERT wrapper, inserts an array into a table.
1702          *
1703          * $a may be either:
1704          *
1705          *   - A single associative array. The array keys are the field names, and
1706          *     the values are the values to insert. The values are treated as data
1707          *     and will be quoted appropriately. If NULL is inserted, this will be
1708          *     converted to a database NULL.
1709          *   - An array with numeric keys, holding a list of associative arrays.
1710          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1711          *     each subarray must be identical to each other, and in the same order.
1712          *
1713          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1714          * returns success.
1715          *
1716          * $options is an array of options, with boolean options encoded as values
1717          * with numeric keys, in the same style as $options in
1718          * DatabaseBase::select(). Supported options are:
1719          *
1720          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1721          *     any rows which cause duplicate key errors are not inserted. It's
1722          *     possible to determine how many rows were successfully inserted using
1723          *     DatabaseBase::affectedRows().
1724          *
1725          * @param $table   String Table name. This will be passed through
1726          *                 DatabaseBase::tableName().
1727          * @param $a       Array of rows to insert
1728          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1729          * @param array $options of options
1730          *
1731          * @return bool
1732          */
1733         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
1734                 # No rows to insert, easy just return now
1735                 if ( !count( $a ) ) {
1736                         return true;
1737                 }
1738
1739                 $table = $this->tableName( $table );
1740
1741                 if ( !is_array( $options ) ) {
1742                         $options = array( $options );
1743                 }
1744
1745                 $fh = null;
1746                 if ( isset( $options['fileHandle'] ) ) {
1747                         $fh = $options['fileHandle'];
1748                 }
1749                 $options = $this->makeInsertOptions( $options );
1750
1751                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1752                         $multi = true;
1753                         $keys = array_keys( $a[0] );
1754                 } else {
1755                         $multi = false;
1756                         $keys = array_keys( $a );
1757                 }
1758
1759                 $sql = 'INSERT ' . $options .
1760                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1761
1762                 if ( $multi ) {
1763                         $first = true;
1764                         foreach ( $a as $row ) {
1765                                 if ( $first ) {
1766                                         $first = false;
1767                                 } else {
1768                                         $sql .= ',';
1769                                 }
1770                                 $sql .= '(' . $this->makeList( $row ) . ')';
1771                         }
1772                 } else {
1773                         $sql .= '(' . $this->makeList( $a ) . ')';
1774                 }
1775
1776                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1777                         return false;
1778                 } elseif ( $fh !== null ) {
1779                         return true;
1780                 }
1781
1782                 return (bool)$this->query( $sql, $fname );
1783         }
1784
1785         /**
1786          * Make UPDATE options for the DatabaseBase::update function
1787          *
1788          * @param array $options The options passed to DatabaseBase::update
1789          * @return string
1790          */
1791         protected function makeUpdateOptions( $options ) {
1792                 if ( !is_array( $options ) ) {
1793                         $options = array( $options );
1794                 }
1795
1796                 $opts = array();
1797
1798                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1799                         $opts[] = $this->lowPriorityOption();
1800                 }
1801
1802                 if ( in_array( 'IGNORE', $options ) ) {
1803                         $opts[] = 'IGNORE';
1804                 }
1805
1806                 return implode( ' ', $opts );
1807         }
1808
1809         /**
1810          * UPDATE wrapper. Takes a condition array and a SET array.
1811          *
1812          * @param $table  String name of the table to UPDATE. This will be passed through
1813          *                DatabaseBase::tableName().
1814          *
1815          * @param array $values  An array of values to SET. For each array element,
1816          *                the key gives the field name, and the value gives the data
1817          *                to set that field to. The data will be quoted by
1818          *                DatabaseBase::addQuotes().
1819          *
1820          * @param $conds  Array:  An array of conditions (WHERE). See
1821          *                DatabaseBase::select() for the details of the format of
1822          *                condition arrays. Use '*' to update all rows.
1823          *
1824          * @param $fname  String: The function name of the caller (from __METHOD__),
1825          *                for logging and profiling.
1826          *
1827          * @param array $options An array of UPDATE options, can be:
1828          *                   - IGNORE: Ignore unique key conflicts
1829          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1830          * @return Boolean
1831          */
1832         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
1833                 $table = $this->tableName( $table );
1834                 $opts = $this->makeUpdateOptions( $options );
1835                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1836
1837                 if ( $conds !== array() && $conds !== '*' ) {
1838                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1839                 }
1840
1841                 return $this->query( $sql, $fname );
1842         }
1843
1844         /**
1845          * Makes an encoded list of strings from an array
1846          * @param array $a containing the data
1847          * @param int $mode Constant
1848          *      - LIST_COMMA:          comma separated, no field names
1849          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1850          *        the documentation for $conds in DatabaseBase::select().
1851          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1852          *      - LIST_SET:            comma separated with field names, like a SET clause
1853          *      - LIST_NAMES:          comma separated field names
1854          *
1855          * @throws MWException|DBUnexpectedError
1856          * @return string
1857          */
1858         public function makeList( $a, $mode = LIST_COMMA ) {
1859                 if ( !is_array( $a ) ) {
1860                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1861                 }
1862
1863                 $first = true;
1864                 $list = '';
1865
1866                 foreach ( $a as $field => $value ) {
1867                         if ( !$first ) {
1868                                 if ( $mode == LIST_AND ) {
1869                                         $list .= ' AND ';
1870                                 } elseif ( $mode == LIST_OR ) {
1871                                         $list .= ' OR ';
1872                                 } else {
1873                                         $list .= ',';
1874                                 }
1875                         } else {
1876                                 $first = false;
1877                         }
1878
1879                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1880                                 $list .= "($value)";
1881                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1882                                 $list .= "$value";
1883                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1884                                 if ( count( $value ) == 0 ) {
1885                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1886                                 } elseif ( count( $value ) == 1 ) {
1887                                         // Special-case single values, as IN isn't terribly efficient
1888                                         // Don't necessarily assume the single key is 0; we don't
1889                                         // enforce linear numeric ordering on other arrays here.
1890                                         $value = array_values( $value );
1891                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1892                                 } else {
1893                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1894                                 }
1895                         } elseif ( $value === null ) {
1896                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1897                                         $list .= "$field IS ";
1898                                 } elseif ( $mode == LIST_SET ) {
1899                                         $list .= "$field = ";
1900                                 }
1901                                 $list .= 'NULL';
1902                         } else {
1903                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1904                                         $list .= "$field = ";
1905                                 }
1906                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1907                         }
1908                 }
1909
1910                 return $list;
1911         }
1912
1913         /**
1914          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1915          * The keys on each level may be either integers or strings.
1916          *
1917          * @param array $data organized as 2-d
1918          *              array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
1919          * @param string $baseKey field name to match the base-level keys to (eg 'pl_namespace')
1920          * @param string $subKey field name to match the sub-level keys to (eg 'pl_title')
1921          * @return Mixed: string SQL fragment, or false if no items in array.
1922          */
1923         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1924                 $conds = array();
1925
1926                 foreach ( $data as $base => $sub ) {
1927                         if ( count( $sub ) ) {
1928                                 $conds[] = $this->makeList(
1929                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1930                                         LIST_AND );
1931                         }
1932                 }
1933
1934                 if ( $conds ) {
1935                         return $this->makeList( $conds, LIST_OR );
1936                 } else {
1937                         // Nothing to search for...
1938                         return false;
1939                 }
1940         }
1941
1942         /**
1943          * Return aggregated value alias
1944          *
1945          * @param $valuedata
1946          * @param $valuename string
1947          *
1948          * @return string
1949          */
1950         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1951                 return $valuename;
1952         }
1953
1954         /**
1955          * @param $field
1956          * @return string
1957          */
1958         public function bitNot( $field ) {
1959                 return "(~$field)";
1960         }
1961
1962         /**
1963          * @param $fieldLeft
1964          * @param $fieldRight
1965          * @return string
1966          */
1967         public function bitAnd( $fieldLeft, $fieldRight ) {
1968                 return "($fieldLeft & $fieldRight)";
1969         }
1970
1971         /**
1972          * @param  $fieldLeft
1973          * @param  $fieldRight
1974          * @return string
1975          */
1976         public function bitOr( $fieldLeft, $fieldRight ) {
1977                 return "($fieldLeft | $fieldRight)";
1978         }
1979
1980         /**
1981          * Build a concatenation list to feed into a SQL query
1982          * @param array $stringList list of raw SQL expressions; caller is responsible for any quoting
1983          * @return String
1984          */
1985         public function buildConcat( $stringList ) {
1986                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1987         }
1988
1989         /**
1990          * Change the current database
1991          *
1992          * @todo Explain what exactly will fail if this is not overridden.
1993          *
1994          * @param $db
1995          *
1996          * @return bool Success or failure
1997          */
1998         public function selectDB( $db ) {
1999                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
2000                 # if your database engine supports a concept similar to MySQL's
2001                 # databases you may as well.
2002                 $this->mDBname = $db;
2003                 return true;
2004         }
2005
2006         /**
2007          * Get the current DB name
2008          */
2009         public function getDBname() {
2010                 return $this->mDBname;
2011         }
2012
2013         /**
2014          * Get the server hostname or IP address
2015          */
2016         public function getServer() {
2017                 return $this->mServer;
2018         }
2019
2020         /**
2021          * Format a table name ready for use in constructing an SQL query
2022          *
2023          * This does two important things: it quotes the table names to clean them up,
2024          * and it adds a table prefix if only given a table name with no quotes.
2025          *
2026          * All functions of this object which require a table name call this function
2027          * themselves. Pass the canonical name to such functions. This is only needed
2028          * when calling query() directly.
2029          *
2030          * @param string $name database table name
2031          * @param string $format One of:
2032          *   quoted - Automatically pass the table name through addIdentifierQuotes()
2033          *            so that it can be used in a query.
2034          *   raw - Do not add identifier quotes to the table name
2035          * @return String: full database name
2036          */
2037         public function tableName( $name, $format = 'quoted' ) {
2038                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
2039                 # Skip the entire process when we have a string quoted on both ends.
2040                 # Note that we check the end so that we will still quote any use of
2041                 # use of `database`.table. But won't break things if someone wants
2042                 # to query a database table with a dot in the name.
2043                 if ( $this->isQuotedIdentifier( $name ) ) {
2044                         return $name;
2045                 }
2046
2047                 # Lets test for any bits of text that should never show up in a table
2048                 # name. Basically anything like JOIN or ON which are actually part of
2049                 # SQL queries, but may end up inside of the table value to combine
2050                 # sql. Such as how the API is doing.
2051                 # Note that we use a whitespace test rather than a \b test to avoid
2052                 # any remote case where a word like on may be inside of a table name
2053                 # surrounded by symbols which may be considered word breaks.
2054                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2055                         return $name;
2056                 }
2057
2058                 # Split database and table into proper variables.
2059                 # We reverse the explode so that database.table and table both output
2060                 # the correct table.
2061                 $dbDetails = explode( '.', $name, 2 );
2062                 if ( count( $dbDetails ) == 2 ) {
2063                         list( $database, $table ) = $dbDetails;
2064                         # We don't want any prefix added in this case
2065                         $prefix = '';
2066                 } else {
2067                         list( $table ) = $dbDetails;
2068                         if ( $wgSharedDB !== null # We have a shared database
2069                                 && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
2070                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
2071                         ) {
2072                                 $database = $wgSharedDB;
2073                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
2074                         } else {
2075                                 $database = null;
2076                                 $prefix = $this->mTablePrefix; # Default prefix
2077                         }
2078                 }
2079
2080                 # Quote $table and apply the prefix if not quoted.
2081                 $tableName = "{$prefix}{$table}";
2082                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) ) {
2083                         $tableName = $this->addIdentifierQuotes( $tableName );
2084                 }
2085
2086                 # Quote $database and merge it with the table name if needed
2087                 if ( $database !== null ) {
2088                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
2089                                 $database = $this->addIdentifierQuotes( $database );
2090                         }
2091                         $tableName = $database . '.' . $tableName;
2092                 }
2093
2094                 return $tableName;
2095         }
2096
2097         /**
2098          * Fetch a number of table names into an array
2099          * This is handy when you need to construct SQL for joins
2100          *
2101          * Example:
2102          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
2103          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2104          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2105          *
2106          * @return array
2107          */
2108         public function tableNames() {
2109                 $inArray = func_get_args();
2110                 $retVal = array();
2111
2112                 foreach ( $inArray as $name ) {
2113                         $retVal[$name] = $this->tableName( $name );
2114                 }
2115
2116                 return $retVal;
2117         }
2118
2119         /**
2120          * Fetch a number of table names into an zero-indexed numerical array
2121          * This is handy when you need to construct SQL for joins
2122          *
2123          * Example:
2124          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
2125          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2126          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2127          *
2128          * @return array
2129          */
2130         public function tableNamesN() {
2131                 $inArray = func_get_args();
2132                 $retVal = array();
2133
2134                 foreach ( $inArray as $name ) {
2135                         $retVal[] = $this->tableName( $name );
2136                 }
2137
2138                 return $retVal;
2139         }
2140
2141         /**
2142          * Get an aliased table name
2143          * e.g. tableName AS newTableName
2144          *
2145          * @param string $name Table name, see tableName()
2146          * @param string|bool $alias Alias (optional)
2147          * @return string SQL name for aliased table. Will not alias a table to its own name
2148          */
2149         public function tableNameWithAlias( $name, $alias = false ) {
2150                 if ( !$alias || $alias == $name ) {
2151                         return $this->tableName( $name );
2152                 } else {
2153                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2154                 }
2155         }
2156
2157         /**
2158          * Gets an array of aliased table names
2159          *
2160          * @param $tables array( [alias] => table )
2161          * @return array of strings, see tableNameWithAlias()
2162          */
2163         public function tableNamesWithAlias( $tables ) {
2164                 $retval = array();
2165                 foreach ( $tables as $alias => $table ) {
2166                         if ( is_numeric( $alias ) ) {
2167                                 $alias = $table;
2168                         }
2169                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2170                 }
2171                 return $retval;
2172         }
2173
2174         /**
2175          * Get an aliased field name
2176          * e.g. fieldName AS newFieldName
2177          *
2178          * @param string $name Field name
2179          * @param string|bool $alias Alias (optional)
2180          * @return string SQL name for aliased field. Will not alias a field to its own name
2181          */
2182         public function fieldNameWithAlias( $name, $alias = false ) {
2183                 if ( !$alias || (string)$alias === (string)$name ) {
2184                         return $name;
2185                 } else {
2186                         return $name . ' AS ' . $alias; //PostgreSQL needs AS
2187                 }
2188         }
2189
2190         /**
2191          * Gets an array of aliased field names
2192          *
2193          * @param $fields array( [alias] => field )
2194          * @return array of strings, see fieldNameWithAlias()
2195          */
2196         public function fieldNamesWithAlias( $fields ) {
2197                 $retval = array();
2198                 foreach ( $fields as $alias => $field ) {
2199                         if ( is_numeric( $alias ) ) {
2200                                 $alias = $field;
2201                         }
2202                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2203                 }
2204                 return $retval;
2205         }
2206
2207         /**
2208          * Get the aliased table name clause for a FROM clause
2209          * which might have a JOIN and/or USE INDEX clause
2210          *
2211          * @param array $tables ( [alias] => table )
2212          * @param $use_index array Same as for select()
2213          * @param $join_conds array Same as for select()
2214          * @return string
2215          */
2216         protected function tableNamesWithUseIndexOrJOIN(
2217                 $tables, $use_index = array(), $join_conds = array()
2218         ) {
2219                 $ret = array();
2220                 $retJOIN = array();
2221                 $use_index = (array)$use_index;
2222                 $join_conds = (array)$join_conds;
2223
2224                 foreach ( $tables as $alias => $table ) {
2225                         if ( !is_string( $alias ) ) {
2226                                 // No alias? Set it equal to the table name
2227                                 $alias = $table;
2228                         }
2229                         // Is there a JOIN clause for this table?
2230                         if ( isset( $join_conds[$alias] ) ) {
2231                                 list( $joinType, $conds ) = $join_conds[$alias];
2232                                 $tableClause = $joinType;
2233                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2234                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2235                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2236                                         if ( $use != '' ) {
2237                                                 $tableClause .= ' ' . $use;
2238                                         }
2239                                 }
2240                                 $on = $this->makeList( (array)$conds, LIST_AND );
2241                                 if ( $on != '' ) {
2242                                         $tableClause .= ' ON (' . $on . ')';
2243                                 }
2244
2245                                 $retJOIN[] = $tableClause;
2246                         // Is there an INDEX clause for this table?
2247                         } elseif ( isset( $use_index[$alias] ) ) {
2248                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2249                                 $tableClause .= ' ' . $this->useIndexClause(
2250                                         implode( ',', (array)$use_index[$alias] ) );
2251
2252                                 $ret[] = $tableClause;
2253                         } else {
2254                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2255
2256                                 $ret[] = $tableClause;
2257                         }
2258                 }
2259
2260                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2261                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2262                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2263
2264                 // Compile our final table clause
2265                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
2266         }
2267
2268         /**
2269          * Get the name of an index in a given table
2270          *
2271          * @param $index
2272          *
2273          * @return string
2274          */
2275         protected function indexName( $index ) {
2276                 // Backwards-compatibility hack
2277                 $renamed = array(
2278                         'ar_usertext_timestamp' => 'usertext_timestamp',
2279                         'un_user_id' => 'user_id',
2280                         'un_user_ip' => 'user_ip',
2281                 );
2282
2283                 if ( isset( $renamed[$index] ) ) {
2284                         return $renamed[$index];
2285                 } else {
2286                         return $index;
2287                 }
2288         }
2289
2290         /**
2291          * If it's a string, adds quotes and backslashes
2292          * Otherwise returns as-is
2293          *
2294          * @param $s string
2295          *
2296          * @return string
2297          */
2298         public function addQuotes( $s ) {
2299                 if ( $s === null ) {
2300                         return 'NULL';
2301                 } else {
2302                         # This will also quote numeric values. This should be harmless,
2303                         # and protects against weird problems that occur when they really
2304                         # _are_ strings such as article titles and string->number->string
2305                         # conversion is not 1:1.
2306                         return "'" . $this->strencode( $s ) . "'";
2307                 }
2308         }
2309
2310         /**
2311          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2312          * MySQL uses `backticks` while basically everything else uses double quotes.
2313          * Since MySQL is the odd one out here the double quotes are our generic
2314          * and we implement backticks in DatabaseMysql.
2315          *
2316          * @param $s string
2317          *
2318          * @return string
2319          */
2320         public function addIdentifierQuotes( $s ) {
2321                 return '"' . str_replace( '"', '""', $s ) . '"';
2322         }
2323
2324         /**
2325          * Returns if the given identifier looks quoted or not according to
2326          * the database convention for quoting identifiers .
2327          *
2328          * @param $name string
2329          *
2330          * @return boolean
2331          */
2332         public function isQuotedIdentifier( $name ) {
2333                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2334         }
2335
2336         /**
2337          * @param $s string
2338          * @return string
2339          */
2340         protected function escapeLikeInternal( $s ) {
2341                 $s = str_replace( '\\', '\\\\', $s );
2342                 $s = $this->strencode( $s );
2343                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2344
2345                 return $s;
2346         }
2347
2348         /**
2349          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2350          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2351          * Alternatively, the function could be provided with an array of aforementioned parameters.
2352          *
2353          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2354          * for subpages of 'My page title'.
2355          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2356          *
2357          * @since 1.16
2358          * @return String: fully built LIKE statement
2359          */
2360         public function buildLike() {
2361                 $params = func_get_args();
2362
2363                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2364                         $params = $params[0];
2365                 }
2366
2367                 $s = '';
2368
2369                 foreach ( $params as $value ) {
2370                         if ( $value instanceof LikeMatch ) {
2371                                 $s .= $value->toString();
2372                         } else {
2373                                 $s .= $this->escapeLikeInternal( $value );
2374                         }
2375                 }
2376
2377                 return " LIKE '" . $s . "' ";
2378         }
2379
2380         /**
2381          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2382          *
2383          * @return LikeMatch
2384          */
2385         public function anyChar() {
2386                 return new LikeMatch( '_' );
2387         }
2388
2389         /**
2390          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2391          *
2392          * @return LikeMatch
2393          */
2394         public function anyString() {
2395                 return new LikeMatch( '%' );
2396         }
2397
2398         /**
2399          * Returns an appropriately quoted sequence value for inserting a new row.
2400          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2401          * subclass will return an integer, and save the value for insertId()
2402          *
2403          * Any implementation of this function should *not* involve reusing
2404          * sequence numbers created for rolled-back transactions.
2405          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2406          * @param $seqName string
2407          * @return null
2408          */
2409         public function nextSequenceValue( $seqName ) {
2410                 return null;
2411         }
2412
2413         /**
2414          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2415          * is only needed because a) MySQL must be as efficient as possible due to
2416          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2417          * which index to pick.  Anyway, other databases might have different
2418          * indexes on a given table.  So don't bother overriding this unless you're
2419          * MySQL.
2420          * @param $index
2421          * @return string
2422          */
2423         public function useIndexClause( $index ) {
2424                 return '';
2425         }
2426
2427         /**
2428          * REPLACE query wrapper.
2429          *
2430          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2431          * except that when there is a duplicate key error, the old row is deleted
2432          * and the new row is inserted in its place.
2433          *
2434          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2435          * perform the delete, we need to know what the unique indexes are so that
2436          * we know how to find the conflicting rows.
2437          *
2438          * It may be more efficient to leave off unique indexes which are unlikely
2439          * to collide. However if you do this, you run the risk of encountering
2440          * errors which wouldn't have occurred in MySQL.
2441          *
2442          * @param string $table The table to replace the row(s) in.
2443          * @param array $rows Can be either a single row to insert, or multiple rows,
2444          *    in the same format as for DatabaseBase::insert()
2445          * @param array $uniqueIndexes is an array of indexes. Each element may be either
2446          *    a field name or an array of field names
2447          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2448          */
2449         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2450                 $quotedTable = $this->tableName( $table );
2451
2452                 if ( count( $rows ) == 0 ) {
2453                         return;
2454                 }
2455
2456                 # Single row case
2457                 if ( !is_array( reset( $rows ) ) ) {
2458                         $rows = array( $rows );
2459                 }
2460
2461                 foreach ( $rows as $row ) {
2462                         # Delete rows which collide
2463                         if ( $uniqueIndexes ) {
2464                                 $sql = "DELETE FROM $quotedTable WHERE ";
2465                                 $first = true;
2466                                 foreach ( $uniqueIndexes as $index ) {
2467                                         if ( $first ) {
2468                                                 $first = false;
2469                                                 $sql .= '( ';
2470                                         } else {
2471                                                 $sql .= ' ) OR ( ';
2472                                         }
2473                                         if ( is_array( $index ) ) {
2474                                                 $first2 = true;
2475                                                 foreach ( $index as $col ) {
2476                                                         if ( $first2 ) {
2477                                                                 $first2 = false;
2478                                                         } else {
2479                                                                 $sql .= ' AND ';
2480                                                         }
2481                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2482                                                 }
2483                                         } else {
2484                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2485                                         }
2486                                 }
2487                                 $sql .= ' )';
2488                                 $this->query( $sql, $fname );
2489                         }
2490
2491                         # Now insert the row
2492                         $this->insert( $table, $row, $fname );
2493                 }
2494         }
2495
2496         /**
2497          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2498          * statement.
2499          *
2500          * @param string $table Table name
2501          * @param array $rows Rows to insert
2502          * @param string $fname Caller function name
2503          *
2504          * @return ResultWrapper
2505          */
2506         protected function nativeReplace( $table, $rows, $fname ) {
2507                 $table = $this->tableName( $table );
2508
2509                 # Single row case
2510                 if ( !is_array( reset( $rows ) ) ) {
2511                         $rows = array( $rows );
2512                 }
2513
2514                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2515                 $first = true;
2516
2517                 foreach ( $rows as $row ) {
2518                         if ( $first ) {
2519                                 $first = false;
2520                         } else {
2521                                 $sql .= ',';
2522                         }
2523
2524                         $sql .= '(' . $this->makeList( $row ) . ')';
2525                 }
2526
2527                 return $this->query( $sql, $fname );
2528         }
2529
2530         /**
2531          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
2532          *
2533          * This updates any conflicting rows (according to the unique indexes) using
2534          * the provided SET clause and inserts any remaining (non-conflicted) rows.
2535          *
2536          * $rows may be either:
2537          *   - A single associative array. The array keys are the field names, and
2538          *     the values are the values to insert. The values are treated as data
2539          *     and will be quoted appropriately. If NULL is inserted, this will be
2540          *     converted to a database NULL.
2541          *   - An array with numeric keys, holding a list of associative arrays.
2542          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2543          *     each subarray must be identical to each other, and in the same order.
2544          *
2545          * It may be more efficient to leave off unique indexes which are unlikely
2546          * to collide. However if you do this, you run the risk of encountering
2547          * errors which wouldn't have occurred in MySQL.
2548          *
2549          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2550          * returns success.
2551          *
2552          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
2553          * @param array $rows A single row or list of rows to insert
2554          * @param array $uniqueIndexes List of single field names or field name tuples
2555          * @param array $set An array of values to SET. For each array element,
2556          *                the key gives the field name, and the value gives the data
2557          *                to set that field to. The data will be quoted by
2558          *                DatabaseBase::addQuotes().
2559          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2560          * @param array $options of options
2561          *
2562          * @return bool
2563          * @since 1.22
2564          */
2565         public function upsert(
2566                 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
2567         ) {
2568                 if ( !count( $rows ) ) {
2569                         return true; // nothing to do
2570                 }
2571                 $rows = is_array( reset( $rows ) ) ? $rows : array( $rows );
2572
2573                 if ( count( $uniqueIndexes ) ) {
2574                         $clauses = array(); // list WHERE clauses that each identify a single row
2575                         foreach ( $rows as $row ) {
2576                                 foreach ( $uniqueIndexes as $index ) {
2577                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2578                                         $rowKey = array(); // unique key to this row
2579                                         foreach ( $index as $column ) {
2580                                                 $rowKey[$column] = $row[$column];
2581                                         }
2582                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2583                                 }
2584                         }
2585                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2586                 } else {
2587                         $where = false;
2588                 }
2589
2590                 $useTrx = !$this->mTrxLevel;
2591                 if ( $useTrx ) {
2592                         $this->begin( $fname );
2593                 }
2594                 try {
2595                         # Update any existing conflicting row(s)
2596                         if ( $where !== false ) {
2597                                 $ok = $this->update( $table, $set, $where, $fname );
2598                         } else {
2599                                 $ok = true;
2600                         }
2601                         # Now insert any non-conflicting row(s)
2602                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2603                 } catch ( Exception $e ) {
2604                         if ( $useTrx ) {
2605                                 $this->rollback( $fname );
2606                         }
2607                         throw $e;
2608                 }
2609                 if ( $useTrx ) {
2610                         $this->commit( $fname );
2611                 }
2612
2613                 return $ok;
2614         }
2615
2616         /**
2617          * DELETE where the condition is a join.
2618          *
2619          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2620          * we use sub-selects
2621          *
2622          * For safety, an empty $conds will not delete everything. If you want to
2623          * delete all rows where the join condition matches, set $conds='*'.
2624          *
2625          * DO NOT put the join condition in $conds.
2626          *
2627          * @param $delTable   String: The table to delete from.
2628          * @param $joinTable  String: The other table.
2629          * @param $delVar     String: The variable to join on, in the first table.
2630          * @param $joinVar    String: The variable to join on, in the second table.
2631          * @param $conds      Array: Condition array of field names mapped to variables,
2632          *                    ANDed together in the WHERE clause
2633          * @param $fname      String: Calling function name (use __METHOD__) for
2634          *                    logs/profiling
2635          * @throws DBUnexpectedError
2636          */
2637         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2638                 $fname = __METHOD__ )
2639         {
2640                 if ( !$conds ) {
2641                         throw new DBUnexpectedError( $this,
2642                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2643                 }
2644
2645                 $delTable = $this->tableName( $delTable );
2646                 $joinTable = $this->tableName( $joinTable );
2647                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2648                 if ( $conds != '*' ) {
2649                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2650                 }
2651                 $sql .= ')';
2652
2653                 $this->query( $sql, $fname );
2654         }
2655
2656         /**
2657          * Returns the size of a text field, or -1 for "unlimited"
2658          *
2659          * @param $table string
2660          * @param $field string
2661          *
2662          * @return int
2663          */
2664         public function textFieldSize( $table, $field ) {
2665                 $table = $this->tableName( $table );
2666                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2667                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2668                 $row = $this->fetchObject( $res );
2669
2670                 $m = array();
2671
2672                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2673                         $size = $m[1];
2674                 } else {
2675                         $size = -1;
2676                 }
2677
2678                 return $size;
2679         }
2680
2681         /**
2682          * A string to insert into queries to show that they're low-priority, like
2683          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2684          * string and nothing bad should happen.
2685          *
2686          * @return string Returns the text of the low priority option if it is
2687          *   supported, or a blank string otherwise
2688          */
2689         public function lowPriorityOption() {
2690                 return '';
2691         }
2692
2693         /**
2694          * DELETE query wrapper.
2695          *
2696          * @param array $table Table name
2697          * @param string|array $conds of conditions. See $conds in DatabaseBase::select() for
2698          *               the format. Use $conds == "*" to delete all rows
2699          * @param string $fname name of the calling function
2700          *
2701          * @throws DBUnexpectedError
2702          * @return bool|ResultWrapper
2703          */
2704         public function delete( $table, $conds, $fname = __METHOD__ ) {
2705                 if ( !$conds ) {
2706                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2707                 }
2708
2709                 $table = $this->tableName( $table );
2710                 $sql = "DELETE FROM $table";
2711
2712                 if ( $conds != '*' ) {
2713                         if ( is_array( $conds ) ) {
2714                                 $conds = $this->makeList( $conds, LIST_AND );
2715                         }
2716                         $sql .= ' WHERE ' . $conds;
2717                 }
2718
2719                 return $this->query( $sql, $fname );
2720         }
2721
2722         /**
2723          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2724          * into another table.
2725          *
2726          * @param string $destTable The table name to insert into
2727          * @param string|array $srcTable May be either a table name, or an array of table names
2728          *    to include in a join.
2729          *
2730          * @param array $varMap must be an associative array of the form
2731          *    array( 'dest1' => 'source1', ...). Source items may be literals
2732          *    rather than field names, but strings should be quoted with
2733          *    DatabaseBase::addQuotes()
2734          *
2735          * @param array $conds Condition array. See $conds in DatabaseBase::select() for
2736          *    the details of the format of condition arrays. May be "*" to copy the
2737          *    whole table.
2738          *
2739          * @param string $fname The function name of the caller, from __METHOD__
2740          *
2741          * @param array $insertOptions Options for the INSERT part of the query, see
2742          *    DatabaseBase::insert() for details.
2743          * @param array $selectOptions Options for the SELECT part of the query, see
2744          *    DatabaseBase::select() for details.
2745          *
2746          * @return ResultWrapper
2747          */
2748         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2749                 $fname = __METHOD__,
2750                 $insertOptions = array(), $selectOptions = array() )
2751         {
2752                 $destTable = $this->tableName( $destTable );
2753
2754                 if ( is_array( $insertOptions ) ) {
2755                         $insertOptions = implode( ' ', $insertOptions );
2756                 }
2757
2758                 if ( !is_array( $selectOptions ) ) {
2759                         $selectOptions = array( $selectOptions );
2760                 }
2761
2762                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2763
2764                 if ( is_array( $srcTable ) ) {
2765                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2766                 } else {
2767                         $srcTable = $this->tableName( $srcTable );
2768                 }
2769
2770                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2771                         " SELECT $startOpts " . implode( ',', $varMap ) .
2772                         " FROM $srcTable $useIndex ";
2773
2774                 if ( $conds != '*' ) {
2775                         if ( is_array( $conds ) ) {
2776                                 $conds = $this->makeList( $conds, LIST_AND );
2777                         }
2778                         $sql .= " WHERE $conds";
2779                 }
2780
2781                 $sql .= " $tailOpts";
2782
2783                 return $this->query( $sql, $fname );
2784         }
2785
2786         /**
2787          * Construct a LIMIT query with optional offset.  This is used for query
2788          * pages.  The SQL should be adjusted so that only the first $limit rows
2789          * are returned.  If $offset is provided as well, then the first $offset
2790          * rows should be discarded, and the next $limit rows should be returned.
2791          * If the result of the query is not ordered, then the rows to be returned
2792          * are theoretically arbitrary.
2793          *
2794          * $sql is expected to be a SELECT, if that makes a difference.
2795          *
2796          * The version provided by default works in MySQL and SQLite.  It will very
2797          * likely need to be overridden for most other DBMSes.
2798          *
2799          * @param string $sql SQL query we will append the limit too
2800          * @param $limit Integer the SQL limit
2801          * @param $offset Integer|bool the SQL offset (default false)
2802          *
2803          * @throws DBUnexpectedError
2804          * @return string
2805          */
2806         public function limitResult( $sql, $limit, $offset = false ) {
2807                 if ( !is_numeric( $limit ) ) {
2808                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2809                 }
2810                 return "$sql LIMIT "
2811                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2812                         . "{$limit} ";
2813         }
2814
2815         /**
2816          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2817          * within the UNION construct.
2818          * @return Boolean
2819          */
2820         public function unionSupportsOrderAndLimit() {
2821                 return true; // True for almost every DB supported
2822         }
2823
2824         /**
2825          * Construct a UNION query
2826          * This is used for providing overload point for other DB abstractions
2827          * not compatible with the MySQL syntax.
2828          * @param array $sqls SQL statements to combine
2829          * @param $all Boolean: use UNION ALL
2830          * @return String: SQL fragment
2831          */
2832         public function unionQueries( $sqls, $all ) {
2833                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2834                 return '(' . implode( $glue, $sqls ) . ')';
2835         }
2836
2837         /**
2838          * Returns an SQL expression for a simple conditional.  This doesn't need
2839          * to be overridden unless CASE isn't supported in your DBMS.
2840          *
2841          * @param string|array $cond SQL expression which will result in a boolean value
2842          * @param string $trueVal SQL expression to return if true
2843          * @param string $falseVal SQL expression to return if false
2844          * @return String: SQL fragment
2845          */
2846         public function conditional( $cond, $trueVal, $falseVal ) {
2847                 if ( is_array( $cond ) ) {
2848                         $cond = $this->makeList( $cond, LIST_AND );
2849                 }
2850                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2851         }
2852
2853         /**
2854          * Returns a comand for str_replace function in SQL query.
2855          * Uses REPLACE() in MySQL
2856          *
2857          * @param string $orig column to modify
2858          * @param string $old column to seek
2859          * @param string $new column to replace with
2860          *
2861          * @return string
2862          */
2863         public function strreplace( $orig, $old, $new ) {
2864                 return "REPLACE({$orig}, {$old}, {$new})";
2865         }
2866
2867         /**
2868          * Determines how long the server has been up
2869          * STUB
2870          *
2871          * @return int
2872          */
2873         public function getServerUptime() {
2874                 return 0;
2875         }
2876
2877         /**
2878          * Determines if the last failure was due to a deadlock
2879          * STUB
2880          *
2881          * @return bool
2882          */
2883         public function wasDeadlock() {
2884                 return false;
2885         }
2886
2887         /**
2888          * Determines if the last failure was due to a lock timeout
2889          * STUB
2890          *
2891          * @return bool
2892          */
2893         public function wasLockTimeout() {
2894                 return false;
2895         }
2896
2897         /**
2898          * Determines if the last query error was something that should be dealt
2899          * with by pinging the connection and reissuing the query.
2900          * STUB
2901          *
2902          * @return bool
2903          */
2904         public function wasErrorReissuable() {
2905                 return false;
2906         }
2907
2908         /**
2909          * Determines if the last failure was due to the database being read-only.
2910          * STUB
2911          *
2912          * @return bool
2913          */
2914         public function wasReadOnlyError() {
2915                 return false;
2916         }
2917
2918         /**
2919          * Perform a deadlock-prone transaction.
2920          *
2921          * This function invokes a callback function to perform a set of write
2922          * queries. If a deadlock occurs during the processing, the transaction
2923          * will be rolled back and the callback function will be called again.
2924          *
2925          * Usage:
2926          *   $dbw->deadlockLoop( callback, ... );
2927          *
2928          * Extra arguments are passed through to the specified callback function.
2929          *
2930          * Returns whatever the callback function returned on its successful,
2931          * iteration, or false on error, for example if the retry limit was
2932          * reached.
2933          *
2934          * @return bool
2935          */
2936         public function deadlockLoop() {
2937                 $this->begin( __METHOD__ );
2938                 $args = func_get_args();
2939                 $function = array_shift( $args );
2940                 $oldIgnore = $this->ignoreErrors( true );
2941                 $tries = self::DEADLOCK_TRIES;
2942
2943                 if ( is_array( $function ) ) {
2944                         $fname = $function[0];
2945                 } else {
2946                         $fname = $function;
2947                 }
2948
2949                 do {
2950                         $retVal = call_user_func_array( $function, $args );
2951                         $error = $this->lastError();
2952                         $errno = $this->lastErrno();
2953                         $sql = $this->lastQuery();
2954
2955                         if ( $errno ) {
2956                                 if ( $this->wasDeadlock() ) {
2957                                         # Retry
2958                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2959                                 } else {
2960                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2961                                 }
2962                         }
2963                 } while ( $this->wasDeadlock() && --$tries > 0 );
2964
2965                 $this->ignoreErrors( $oldIgnore );
2966
2967                 if ( $tries <= 0 ) {
2968                         $this->rollback( __METHOD__ );
2969                         $this->reportQueryError( $error, $errno, $sql, $fname );
2970                         return false;
2971                 } else {
2972                         $this->commit( __METHOD__ );
2973                         return $retVal;
2974                 }
2975         }
2976
2977         /**
2978          * Wait for the slave to catch up to a given master position.
2979          *
2980          * @param $pos DBMasterPos object
2981          * @param $timeout Integer: the maximum number of seconds to wait for
2982          *   synchronisation
2983          *
2984          * @return integer: zero if the slave was past that position already,
2985          *   greater than zero if we waited for some period of time, less than
2986          *   zero if we timed out.
2987          */
2988         public function masterPosWait( DBMasterPos $pos, $timeout ) {
2989                 wfProfileIn( __METHOD__ );
2990
2991                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2992                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2993
2994                         if ( $wait > $timeout * 1e6 ) {
2995                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2996                                 wfProfileOut( __METHOD__ );
2997                                 return -1;
2998                         } elseif ( $wait > 0 ) {
2999                                 wfDebug( "Fake slave waiting $wait us\n" );
3000                                 usleep( $wait );
3001                                 wfProfileOut( __METHOD__ );
3002                                 return 1;
3003                         } else {
3004                                 wfDebug( "Fake slave up to date ($wait us)\n" );
3005                                 wfProfileOut( __METHOD__ );
3006                                 return 0;
3007                         }
3008                 }
3009
3010                 wfProfileOut( __METHOD__ );
3011
3012                 # Real waits are implemented in the subclass.
3013                 return 0;
3014         }
3015
3016         /**
3017          * Get the replication position of this slave
3018          *
3019          * @return DBMasterPos, or false if this is not a slave.
3020          */
3021         public function getSlavePos() {
3022                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3023                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
3024                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
3025                         return $pos;
3026                 } else {
3027                         # Stub
3028                         return false;
3029                 }
3030         }
3031
3032         /**
3033          * Get the position of this master
3034          *
3035          * @return DBMasterPos, or false if this is not a master
3036          */
3037         public function getMasterPos() {
3038                 if ( $this->mFakeMaster ) {
3039                         return new MySQLMasterPos( 'fake', microtime( true ) );
3040                 } else {
3041                         return false;
3042                 }
3043         }
3044
3045         /**
3046          * Run an anonymous function as soon as there is no transaction pending.
3047          * If there is a transaction and it is rolled back, then the callback is cancelled.
3048          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
3049          * Callbacks must commit any transactions that they begin.
3050          *
3051          * This is useful for updates to different systems or when separate transactions are needed.
3052          * For example, one might want to enqueue jobs into a system outside the database, but only
3053          * after the database is updated so that the jobs will see the data when they actually run.
3054          * It can also be used for updates that easily cause deadlocks if locks are held too long.
3055          *
3056          * @param callable $callback
3057          * @since 1.20
3058          */
3059         final public function onTransactionIdle( $callback ) {
3060                 $this->mTrxIdleCallbacks[] = $callback;
3061                 if ( !$this->mTrxLevel ) {
3062                         $this->runOnTransactionIdleCallbacks();
3063                 }
3064         }
3065
3066         /**
3067          * Run an anonymous function before the current transaction commits or now if there is none.
3068          * If there is a transaction and it is rolled back, then the callback is cancelled.
3069          * Callbacks must not start nor commit any transactions.
3070          *
3071          * This is useful for updates that easily cause deadlocks if locks are held too long
3072          * but where atomicity is strongly desired for these updates and some related updates.
3073          *
3074          * @param callable $callback
3075          * @since 1.22
3076          */
3077         final public function onTransactionPreCommitOrIdle( $callback ) {
3078                 if ( $this->mTrxLevel ) {
3079                         $this->mTrxPreCommitCallbacks[] = $callback;
3080                 } else {
3081                         $this->onTransactionIdle( $callback ); // this will trigger immediately
3082                 }
3083         }
3084
3085         /**
3086          * Actually any "on transaction idle" callbacks.
3087          *
3088          * @since 1.20
3089          */
3090         protected function runOnTransactionIdleCallbacks() {
3091                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
3092
3093                 $e = null; // last exception
3094                 do { // callbacks may add callbacks :)
3095                         $callbacks = $this->mTrxIdleCallbacks;
3096                         $this->mTrxIdleCallbacks = array(); // recursion guard
3097                         foreach ( $callbacks as $callback ) {
3098                                 try {
3099                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
3100                                         $callback();
3101                                         $this->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore automatic begin()
3102                                 } catch ( Exception $e ) {
3103                                 }
3104                         }
3105                 } while ( count( $this->mTrxIdleCallbacks ) );
3106
3107                 if ( $e instanceof Exception ) {
3108                         throw $e; // re-throw any last exception
3109                 }
3110         }
3111
3112         /**
3113          * Actually any "on transaction pre-commit" callbacks.
3114          *
3115          * @since 1.22
3116          */
3117         protected function runOnTransactionPreCommitCallbacks() {
3118                 $e = null; // last exception
3119                 do { // callbacks may add callbacks :)
3120                         $callbacks = $this->mTrxPreCommitCallbacks;
3121                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
3122                         foreach ( $callbacks as $callback ) {
3123                                 try {
3124                                         $callback();
3125                                 } catch ( Exception $e ) {}
3126                         }
3127                 } while ( count( $this->mTrxPreCommitCallbacks ) );
3128
3129                 if ( $e instanceof Exception ) {
3130                         throw $e; // re-throw any last exception
3131                 }
3132         }
3133
3134         /**
3135          * Begin a transaction. If a transaction is already in progress, that transaction will be committed before the
3136          * new transaction is started.
3137          *
3138          * Note that when the DBO_TRX flag is set (which is usually the case for web requests, but not for maintenance scripts),
3139          * any previous database query will have started a transaction automatically.
3140          *
3141          * Nesting of transactions is not supported. Attempts to nest transactions will cause a warning, unless the current
3142          * transaction was started automatically because of the DBO_TRX flag.
3143          *
3144          * @param $fname string
3145          */
3146         final public function begin( $fname = __METHOD__ ) {
3147                 global $wgDebugDBTransactions;
3148
3149                 if ( $this->mTrxLevel ) { // implicit commit
3150                         if ( !$this->mTrxAutomatic ) {
3151                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
3152                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
3153                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
3154                                         " performing implicit commit!";
3155                                 wfWarn( $msg );
3156                                 wfLogDBError( $msg );
3157                         } else {
3158                                 // if the transaction was automatic and has done write operations,
3159                                 // log it if $wgDebugDBTransactions is enabled.
3160                                 if ( $this->mTrxDoneWrites && $wgDebugDBTransactions ) {
3161                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
3162                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
3163                                         );
3164                                 }
3165                         }
3166
3167                         $this->runOnTransactionPreCommitCallbacks();
3168                         $this->doCommit( $fname );
3169                         $this->runOnTransactionIdleCallbacks();
3170                 }
3171
3172                 $this->doBegin( $fname );
3173                 $this->mTrxFname = $fname;
3174                 $this->mTrxDoneWrites = false;
3175                 $this->mTrxAutomatic = false;
3176         }
3177
3178         /**
3179          * Issues the BEGIN command to the database server.
3180          *
3181          * @see DatabaseBase::begin()
3182          * @param type $fname
3183          */
3184         protected function doBegin( $fname ) {
3185                 $this->query( 'BEGIN', $fname );
3186                 $this->mTrxLevel = 1;
3187         }
3188
3189         /**
3190          * Commits a transaction previously started using begin().
3191          * If no transaction is in progress, a warning is issued.
3192          *
3193          * Nesting of transactions is not supported.
3194          *
3195          * @param $fname string
3196          * @param string $flush Flush flag, set to 'flush' to disable warnings about explicitly committing implicit
3197          *        transactions, or calling commit when no transaction is in progress.
3198          *        This will silently break any ongoing explicit transaction. Only set the flush flag if you are sure
3199          *        that it is safe to ignore these warnings in your context.
3200          */
3201         final public function commit( $fname = __METHOD__, $flush = '' ) {
3202                 if ( $flush != 'flush' ) {
3203                         if ( !$this->mTrxLevel ) {
3204                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
3205                         } elseif ( $this->mTrxAutomatic ) {
3206                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
3207                         }
3208                 } else {
3209                         if ( !$this->mTrxLevel ) {
3210                                 return; // nothing to do
3211                         } elseif ( !$this->mTrxAutomatic ) {
3212                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3213                         }
3214                 }
3215
3216                 $this->runOnTransactionPreCommitCallbacks();
3217                 $this->doCommit( $fname );
3218                 $this->runOnTransactionIdleCallbacks();
3219         }
3220
3221         /**
3222          * Issues the COMMIT command to the database server.
3223          *
3224          * @see DatabaseBase::commit()
3225          * @param type $fname
3226          */
3227         protected function doCommit( $fname ) {
3228                 if ( $this->mTrxLevel ) {
3229                         $this->query( 'COMMIT', $fname );
3230                         $this->mTrxLevel = 0;
3231                 }
3232         }
3233
3234         /**
3235          * Rollback a transaction previously started using begin().
3236          * If no transaction is in progress, a warning is issued.
3237          *
3238          * No-op on non-transactional databases.
3239          *
3240          * @param $fname string
3241          */
3242         final public function rollback( $fname = __METHOD__ ) {
3243                 if ( !$this->mTrxLevel ) {
3244                         wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
3245                 }
3246                 $this->doRollback( $fname );
3247                 $this->mTrxIdleCallbacks = array(); // cancel
3248                 $this->mTrxPreCommitCallbacks = array(); // cancel
3249         }
3250
3251         /**
3252          * Issues the ROLLBACK command to the database server.
3253          *
3254          * @see DatabaseBase::rollback()
3255          * @param type $fname
3256          */
3257         protected function doRollback( $fname ) {
3258                 if ( $this->mTrxLevel ) {
3259                         $this->query( 'ROLLBACK', $fname, true );
3260                         $this->mTrxLevel = 0;
3261                 }
3262         }
3263
3264         /**
3265          * Creates a new table with structure copied from existing table
3266          * Note that unlike most database abstraction functions, this function does not
3267          * automatically append database prefix, because it works at a lower
3268          * abstraction level.
3269          * The table names passed to this function shall not be quoted (this
3270          * function calls addIdentifierQuotes when needed).
3271          *
3272          * @param string $oldName name of table whose structure should be copied
3273          * @param string $newName name of table to be created
3274          * @param $temporary Boolean: whether the new table should be temporary
3275          * @param string $fname calling function name
3276          * @throws MWException
3277          * @return Boolean: true if operation was successful
3278          */
3279         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3280                 $fname = __METHOD__
3281         ) {
3282                 throw new MWException(
3283                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3284         }
3285
3286         /**
3287          * List all tables on the database
3288          *
3289          * @param string $prefix Only show tables with this prefix, e.g. mw_
3290          * @param string $fname calling function name
3291          * @throws MWException
3292          */
3293         function listTables( $prefix = null, $fname = __METHOD__ ) {
3294                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3295         }
3296
3297         /**
3298          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3299          * to the format used for inserting into timestamp fields in this DBMS.
3300          *
3301          * The result is unquoted, and needs to be passed through addQuotes()
3302          * before it can be included in raw SQL.
3303          *
3304          * @param $ts string|int
3305          *
3306          * @return string
3307          */
3308         public function timestamp( $ts = 0 ) {
3309                 return wfTimestamp( TS_MW, $ts );
3310         }
3311
3312         /**
3313          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3314          * to the format used for inserting into timestamp fields in this DBMS. If
3315          * NULL is input, it is passed through, allowing NULL values to be inserted
3316          * into timestamp fields.
3317          *
3318          * The result is unquoted, and needs to be passed through addQuotes()
3319          * before it can be included in raw SQL.
3320          *
3321          * @param $ts string|int
3322          *
3323          * @return string
3324          */
3325         public function timestampOrNull( $ts = null ) {
3326                 if ( is_null( $ts ) ) {
3327                         return null;
3328                 } else {
3329                         return $this->timestamp( $ts );
3330                 }
3331         }
3332
3333         /**
3334          * Take the result from a query, and wrap it in a ResultWrapper if
3335          * necessary. Boolean values are passed through as is, to indicate success
3336          * of write queries or failure.
3337          *
3338          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3339          * resource, and it was necessary to call this function to convert it to
3340          * a wrapper. Nowadays, raw database objects are never exposed to external
3341          * callers, so this is unnecessary in external code. For compatibility with
3342          * old code, ResultWrapper objects are passed through unaltered.
3343          *
3344          * @param $result bool|ResultWrapper
3345          *
3346          * @return bool|ResultWrapper
3347          */
3348         public function resultObject( $result ) {
3349                 if ( empty( $result ) ) {
3350                         return false;
3351                 } elseif ( $result instanceof ResultWrapper ) {
3352                         return $result;
3353                 } elseif ( $result === true ) {
3354                         // Successful write query
3355                         return $result;
3356                 } else {
3357                         return new ResultWrapper( $this, $result );
3358                 }
3359         }
3360
3361         /**
3362          * Ping the server and try to reconnect if it there is no connection
3363          *
3364          * @return bool Success or failure
3365          */
3366         public function ping() {
3367                 # Stub.  Not essential to override.
3368                 return true;
3369         }
3370
3371         /**
3372          * Get slave lag. Currently supported only by MySQL.
3373          *
3374          * Note that this function will generate a fatal error on many
3375          * installations. Most callers should use LoadBalancer::safeGetLag()
3376          * instead.
3377          *
3378          * @return int Database replication lag in seconds
3379          */
3380         public function getLag() {
3381                 return intval( $this->mFakeSlaveLag );
3382         }
3383
3384         /**
3385          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3386          *
3387          * @return int
3388          */
3389         function maxListLen() {
3390                 return 0;
3391         }
3392
3393         /**
3394          * Some DBMSs have a special format for inserting into blob fields, they
3395          * don't allow simple quoted strings to be inserted. To insert into such
3396          * a field, pass the data through this function before passing it to
3397          * DatabaseBase::insert().
3398          * @param $b string
3399          * @return string
3400          */
3401         public function encodeBlob( $b ) {
3402                 return $b;
3403         }
3404
3405         /**
3406          * Some DBMSs return a special placeholder object representing blob fields
3407          * in result objects. Pass the object through this function to return the
3408          * original string.
3409          * @param $b string
3410          * @return string
3411          */
3412         public function decodeBlob( $b ) {
3413                 return $b;
3414         }
3415
3416         /**
3417          * Override database's default behavior. $options include:
3418          *     'connTimeout' : Set the connection timeout value in seconds.
3419          *                     May be useful for very long batch queries such as
3420          *                     full-wiki dumps, where a single query reads out over
3421          *                     hours or days.
3422          *
3423          * @param $options Array
3424          * @return void
3425          */
3426         public function setSessionOptions( array $options ) {
3427         }
3428
3429         /**
3430          * Read and execute SQL commands from a file.
3431          *
3432          * Returns true on success, error string or exception on failure (depending
3433          * on object's error ignore settings).
3434          *
3435          * @param string $filename File name to open
3436          * @param bool|callable $lineCallback Optional function called before reading each line
3437          * @param bool|callable $resultCallback Optional function called for each MySQL result
3438          * @param bool|string $fname Calling function name or false if name should be
3439          *      generated dynamically using $filename
3440          * @param bool|callable $inputCallback Callback: Optional function called for each complete line sent
3441          * @throws MWException
3442          * @throws Exception|MWException
3443          * @return bool|string
3444          */
3445         public function sourceFile(
3446                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3447         ) {
3448                 wfSuppressWarnings();
3449                 $fp = fopen( $filename, 'r' );
3450                 wfRestoreWarnings();
3451
3452                 if ( false === $fp ) {
3453                         throw new MWException( "Could not open \"{$filename}\".\n" );
3454                 }
3455
3456                 if ( !$fname ) {
3457                         $fname = __METHOD__ . "( $filename )";
3458                 }
3459
3460                 try {
3461                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3462                 }
3463                 catch ( MWException $e ) {
3464                         fclose( $fp );
3465                         throw $e;
3466                 }
3467
3468                 fclose( $fp );
3469
3470                 return $error;
3471         }
3472
3473         /**
3474          * Get the full path of a patch file. Originally based on archive()
3475          * from updaters.inc. Keep in mind this always returns a patch, as
3476          * it fails back to MySQL if no DB-specific patch can be found
3477          *
3478          * @param string $patch The name of the patch, like patch-something.sql
3479          * @return String Full path to patch file
3480          */
3481         public function patchPath( $patch ) {
3482                 global $IP;
3483
3484                 $dbType = $this->getType();
3485                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3486                         return "$IP/maintenance/$dbType/archives/$patch";
3487                 } else {
3488                         return "$IP/maintenance/archives/$patch";
3489                 }
3490         }
3491
3492         /**
3493          * Set variables to be used in sourceFile/sourceStream, in preference to the
3494          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3495          * all. If it's set to false, $GLOBALS will be used.
3496          *
3497          * @param bool|array $vars mapping variable name to value.
3498          */
3499         public function setSchemaVars( $vars ) {
3500                 $this->mSchemaVars = $vars;
3501         }
3502
3503         /**
3504          * Read and execute commands from an open file handle.
3505          *
3506          * Returns true on success, error string or exception on failure (depending
3507          * on object's error ignore settings).
3508          *
3509          * @param $fp Resource: File handle
3510          * @param $lineCallback Callback: Optional function called before reading each query
3511          * @param $resultCallback Callback: Optional function called for each MySQL result
3512          * @param string $fname Calling function name
3513          * @param $inputCallback Callback: Optional function called for each complete query sent
3514          * @return bool|string
3515          */
3516         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3517                 $fname = __METHOD__, $inputCallback = false )
3518         {
3519                 $cmd = '';
3520
3521                 while ( !feof( $fp ) ) {
3522                         if ( $lineCallback ) {
3523                                 call_user_func( $lineCallback );
3524                         }
3525
3526                         $line = trim( fgets( $fp ) );
3527
3528                         if ( $line == '' ) {
3529                                 continue;
3530                         }
3531
3532                         if ( '-' == $line[0] && '-' == $line[1] ) {
3533                                 continue;
3534                         }
3535
3536                         if ( $cmd != '' ) {
3537                                 $cmd .= ' ';
3538                         }
3539
3540                         $done = $this->streamStatementEnd( $cmd, $line );
3541
3542                         $cmd .= "$line\n";
3543
3544                         if ( $done || feof( $fp ) ) {
3545                                 $cmd = $this->replaceVars( $cmd );
3546
3547                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3548                                         $res = $this->query( $cmd, $fname );
3549
3550                                         if ( $resultCallback ) {
3551                                                 call_user_func( $resultCallback, $res, $this );
3552                                         }
3553
3554                                         if ( false === $res ) {
3555                                                 $err = $this->lastError();
3556                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3557                                         }
3558                                 }
3559                                 $cmd = '';
3560                         }
3561                 }
3562
3563                 return true;
3564         }
3565
3566         /**
3567          * Called by sourceStream() to check if we've reached a statement end
3568          *
3569          * @param string $sql SQL assembled so far
3570          * @param string $newLine New line about to be added to $sql
3571          * @return Bool Whether $newLine contains end of the statement
3572          */
3573         public function streamStatementEnd( &$sql, &$newLine ) {
3574                 if ( $this->delimiter ) {
3575                         $prev = $newLine;
3576                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3577                         if ( $newLine != $prev ) {
3578                                 return true;
3579                         }
3580                 }
3581                 return false;
3582         }
3583
3584         /**
3585          * Database independent variable replacement. Replaces a set of variables
3586          * in an SQL statement with their contents as given by $this->getSchemaVars().
3587          *
3588          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3589          *
3590          * - '{$var}' should be used for text and is passed through the database's
3591          *   addQuotes method.
3592          * - `{$var}` should be used for identifiers (eg: table and database names),
3593          *   it is passed through the database's addIdentifierQuotes method which
3594          *   can be overridden if the database uses something other than backticks.
3595          * - / *$var* / is just encoded, besides traditional table prefix and
3596          *   table options its use should be avoided.
3597          *
3598          * @param string $ins SQL statement to replace variables in
3599          * @return String The new SQL statement with variables replaced
3600          */
3601         protected function replaceSchemaVars( $ins ) {
3602                 $vars = $this->getSchemaVars();
3603                 foreach ( $vars as $var => $value ) {
3604                         // replace '{$var}'
3605                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3606                         // replace `{$var}`
3607                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3608                         // replace /*$var*/
3609                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ), $ins );
3610                 }
3611                 return $ins;
3612         }
3613
3614         /**
3615          * Replace variables in sourced SQL
3616          *
3617          * @param $ins string
3618          *
3619          * @return string
3620          */
3621         protected function replaceVars( $ins ) {
3622                 $ins = $this->replaceSchemaVars( $ins );
3623
3624                 // Table prefixes
3625                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3626                         array( $this, 'tableNameCallback' ), $ins );
3627
3628                 // Index names
3629                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3630                         array( $this, 'indexNameCallback' ), $ins );
3631
3632                 return $ins;
3633         }
3634
3635         /**
3636          * Get schema variables. If none have been set via setSchemaVars(), then
3637          * use some defaults from the current object.
3638          *
3639          * @return array
3640          */
3641         protected function getSchemaVars() {
3642                 if ( $this->mSchemaVars ) {
3643                         return $this->mSchemaVars;
3644                 } else {
3645                         return $this->getDefaultSchemaVars();
3646                 }
3647         }
3648
3649         /**
3650          * Get schema variables to use if none have been set via setSchemaVars().
3651          *
3652          * Override this in derived classes to provide variables for tables.sql
3653          * and SQL patch files.
3654          *
3655          * @return array
3656          */
3657         protected function getDefaultSchemaVars() {
3658                 return array();
3659         }
3660
3661         /**
3662          * Table name callback
3663          *
3664          * @param $matches array
3665          *
3666          * @return string
3667          */
3668         protected function tableNameCallback( $matches ) {
3669                 return $this->tableName( $matches[1] );
3670         }
3671
3672         /**
3673          * Index name callback
3674          *
3675          * @param $matches array
3676          *
3677          * @return string
3678          */
3679         protected function indexNameCallback( $matches ) {
3680                 return $this->indexName( $matches[1] );
3681         }
3682
3683         /**
3684          * Check to see if a named lock is available. This is non-blocking.
3685          *
3686          * @param string $lockName name of lock to poll
3687          * @param string $method name of method calling us
3688          * @return Boolean
3689          * @since 1.20
3690          */
3691         public function lockIsFree( $lockName, $method ) {
3692                 return true;
3693         }
3694
3695         /**
3696          * Acquire a named lock
3697          *
3698          * Abstracted from Filestore::lock() so child classes can implement for
3699          * their own needs.
3700          *
3701          * @param string $lockName name of lock to aquire
3702          * @param string $method name of method calling us
3703          * @param $timeout Integer: timeout
3704          * @return Boolean
3705          */
3706         public function lock( $lockName, $method, $timeout = 5 ) {
3707                 return true;
3708         }
3709
3710         /**
3711          * Release a lock.
3712          *
3713          * @param string $lockName Name of lock to release
3714          * @param string $method Name of method calling us
3715          *
3716          * @return int Returns 1 if the lock was released, 0 if the lock was not established
3717          * by this thread (in which case the lock is not released), and NULL if the named
3718          * lock did not exist
3719          */
3720         public function unlock( $lockName, $method ) {
3721                 return true;
3722         }
3723
3724         /**
3725          * Lock specific tables
3726          *
3727          * @param array $read of tables to lock for read access
3728          * @param array $write of tables to lock for write access
3729          * @param string $method name of caller
3730          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3731          *
3732          * @return bool
3733          */
3734         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3735                 return true;
3736         }
3737
3738         /**
3739          * Unlock specific tables
3740          *
3741          * @param string $method the caller
3742          *
3743          * @return bool
3744          */
3745         public function unlockTables( $method ) {
3746                 return true;
3747         }
3748
3749         /**
3750          * Delete a table
3751          * @param $tableName string
3752          * @param $fName string
3753          * @return bool|ResultWrapper
3754          * @since 1.18
3755          */
3756         public function dropTable( $tableName, $fName = __METHOD__ ) {
3757                 if ( !$this->tableExists( $tableName, $fName ) ) {
3758                         return false;
3759                 }
3760                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3761                 if ( $this->cascadingDeletes() ) {
3762                         $sql .= " CASCADE";
3763                 }
3764                 return $this->query( $sql, $fName );
3765         }
3766
3767         /**
3768          * Get search engine class. All subclasses of this need to implement this
3769          * if they wish to use searching.
3770          *
3771          * @return String
3772          */
3773         public function getSearchEngine() {
3774                 return 'SearchEngineDummy';
3775         }
3776
3777         /**
3778          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3779          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3780          * because "i" sorts after all numbers.
3781          *
3782          * @return String
3783          */
3784         public function getInfinity() {
3785                 return 'infinity';
3786         }
3787
3788         /**
3789          * Encode an expiry time into the DBMS dependent format
3790          *
3791          * @param string $expiry timestamp for expiry, or the 'infinity' string
3792          * @return String
3793          */
3794         public function encodeExpiry( $expiry ) {
3795                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3796                         ? $this->getInfinity()
3797                         : $this->timestamp( $expiry );
3798         }
3799
3800         /**
3801          * Decode an expiry time into a DBMS independent format
3802          *
3803          * @param string $expiry DB timestamp field value for expiry
3804          * @param $format integer: TS_* constant, defaults to TS_MW
3805          * @return String
3806          */
3807         public function decodeExpiry( $expiry, $format = TS_MW ) {
3808                 return ( $expiry == '' || $expiry == $this->getInfinity() )
3809                         ? 'infinity'
3810                         : wfTimestamp( $format, $expiry );
3811         }
3812
3813         /**
3814          * Allow or deny "big selects" for this session only. This is done by setting
3815          * the sql_big_selects session variable.
3816          *
3817          * This is a MySQL-specific feature.
3818          *
3819          * @param $value Mixed: true for allow, false for deny, or "default" to
3820          *   restore the initial value
3821          */
3822         public function setBigSelects( $value = true ) {
3823                 // no-op
3824         }
3825
3826         /**
3827          * @since 1.19
3828          */
3829         public function __toString() {
3830                 return (string)$this->mConn;
3831         }
3832
3833         public function __destruct() {
3834                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
3835                         trigger_error( "Transaction idle or pre-commit callbacks still pending." ); // sanity
3836                 }
3837         }
3838 }