includes/Database.php

   1 <?php
   2 /**
   3  * This file deals with MySQL interface functions
   4  * and query specifics/optimisations
   5  * @package MediaWiki
   6  */
   7
   8 /**
   9  * Depends on the CacheManager
  10  */
  11 require_once( 'CacheManager.php' );
  12
  13 /** See Database::makeList() */
  14 define( 'LIST_COMMA', 0 );
  15 define( 'LIST_AND', 1 );
  16 define( 'LIST_SET', 2 );
  17 define( 'LIST_NAMES', 3);
  18 define( 'LIST_OR', 4);
  19
  20 /** Number of times to re-try an operation in case of deadlock */
  21 define( 'DEADLOCK_TRIES', 4 );
  22 /** Minimum time to wait before retry, in microseconds */
  23 define( 'DEADLOCK_DELAY_MIN', 500000 );
  24 /** Maximum time to wait before retry */
  25 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  26
  27 class DBObject {
  28         var $mData;
  29
  30         function DBObject($data) {
  31                 $this->mData = $data;
  32         }
  33
  34         function isLOB() {
  35                 return false;
  36         }
  37
  38         function data() {
  39                 return $this->mData;
  40         }
  41 };
  42
  43 /**
  44  * Database abstraction object
  45  * @package MediaWiki
  46  */
  47 class Database {
  48
  49 #------------------------------------------------------------------------------
  50 # Variables
  51 #------------------------------------------------------------------------------
  52         /**#@+
  53          * @access private
  54          */
  55         var $mLastQuery = '';
  56
  57         var $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
  58         var $mOut, $mOpened = false;
  59
  60         var $mFailFunction;
  61         var $mTablePrefix;
  62         var $mFlags;
  63         var $mTrxLevel = 0;
  64         var $mErrorCount = 0;
  65         /**#@-*/
  66
  67 #------------------------------------------------------------------------------
  68 # Accessors
  69 #------------------------------------------------------------------------------
  70         # These optionally set a variable and return the previous state
  71
  72         /**
  73          * Fail function, takes a Database as a parameter
  74          * Set to false for default, 1 for ignore errors
  75          */
  76         function failFunction( $function = NULL ) {
  77                 return wfSetVar( $this->mFailFunction, $function );
  78         }
  79
  80         /**
  81          * Output page, used for reporting errors
  82          * FALSE means discard output
  83          */
  84         function &setOutputPage( &$out ) {
  85                 $this->mOut =& $out;
  86         }
  87
  88         /**
  89          * Boolean, controls output of large amounts of debug information
  90          */
  91         function debug( $debug = NULL ) {
  92                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
  93         }
  94
  95         /**
  96          * Turns buffering of SQL result sets on (true) or off (false).
  97          * Default is "on" and it should not be changed without good reasons.
  98          */
  99         function bufferResults( $buffer = NULL ) {
 100                 if ( is_null( $buffer ) ) {
 101                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 102                 } else {
 103                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 104                 }
 105         }
 106
 107         /**
 108          * Turns on (false) or off (true) the automatic generation and sending
 109          * of a "we're sorry, but there has been a database error" page on
 110          * database errors. Default is on (false). When turned off, the
 111          * code should use wfLastErrno() and wfLastError() to handle the
 112          * situation as appropriate.
 113          */
 114         function ignoreErrors( $ignoreErrors = NULL ) {
 115                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 116         }
 117
 118         /**
 119          * The current depth of nested transactions
 120          * @param integer $level
 121          */
 122         function trxLevel( $level = NULL ) {
 123                 return wfSetVar( $this->mTrxLevel, $level );
 124         }
 125
 126         /**
 127          * Number of errors logged, only useful when errors are ignored
 128          */
 129         function errorCount( $count = NULL ) {
 130                 return wfSetVar( $this->mErrorCount, $count );
 131         }
 132
 133         /**#@+
 134          * Get function
 135          */
 136         function lastQuery() { return $this->mLastQuery; }
 137         function isOpen() { return $this->mOpened; }
 138         /**#@-*/
 139
 140         function setFlag( $flag ) {
 141                 $this->mFlags |= $flag;
 142         }
 143
 144         function clearFlag( $flag ) {
 145                 $this->mFlags &= ~$flag;
 146         }
 147
 148         function getFlag( $flag ) {
 149                 return !!($this->mFlags & $flag);
 150         }
 151
 152 #------------------------------------------------------------------------------
 153 # Other functions
 154 #------------------------------------------------------------------------------
 155
 156         /**#@+
 157          * @param string $server database server host
 158          * @param string $user database user name
 159          * @param string $password database user password
 160          * @param string $dbname database name
 161          */
 162
 163         /**
 164          * @param failFunction
 165          * @param $flags
 166          * @param string $tablePrefix Database table prefixes. By default use the prefix gave in LocalSettings.php
 167          */
 168         function Database( $server = false, $user = false, $password = false, $dbName = false,
 169                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global' ) {
 170
 171                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 172                 # Can't get a reference if it hasn't been set yet
 173                 if ( !isset( $wgOut ) ) {
 174                         $wgOut = NULL;
 175                 }
 176                 $this->mOut =& $wgOut;
 177
 178                 $this->mFailFunction = $failFunction;
 179                 $this->mFlags = $flags;
 180
 181                 if ( $this->mFlags & DBO_DEFAULT ) {
 182                         if ( $wgCommandLineMode ) {
 183                                 $this->mFlags &= ~DBO_TRX;
 184                         } else {
 185                                 $this->mFlags |= DBO_TRX;
 186                         }
 187                 }
 188
 189                 /*
 190                 // Faster read-only access
 191                 if ( wfReadOnly() ) {
 192                         $this->mFlags |= DBO_PERSISTENT;
 193                         $this->mFlags &= ~DBO_TRX;
 194                 }*/
 195
 196                 /** Get the default table prefix*/
 197                 if ( $tablePrefix == 'get from global' ) {
 198                         $this->mTablePrefix = $wgDBprefix;
 199                 } else {
 200                         $this->mTablePrefix = $tablePrefix;
 201                 }
 202
 203                 if ( $server ) {
 204                         $this->open( $server, $user, $password, $dbName );
 205                 }
 206         }
 207
 208         /**
 209          * @static
 210          * @param failFunction
 211          * @param $flags
 212          */
 213         function newFromParams( $server, $user, $password, $dbName,
 214                 $failFunction = false, $flags = 0 )
 215         {
 216                 return new Database( $server, $user, $password, $dbName, $failFunction, $flags );
 217         }
 218
 219         /**
 220          * Usually aborts on failure
 221          * If the failFunction is set to a non-zero integer, returns success
 222          */
 223         function open( $server, $user, $password, $dbName ) {
 224                 # Test for missing mysql.so
 225                 # First try to load it
 226                 if (!@extension_loaded('mysql')) {
 227                         @dl('mysql.so');
 228                 }
 229
 230                 # Otherwise we get a suppressed fatal error, which is very hard to track down
 231                 if ( !function_exists( 'mysql_connect' ) ) {
 232                         die( "MySQL functions missing, have you compiled PHP with the --with-mysql option?\n" );
 233                 }
 234
 235                 $this->close();
 236                 $this->mServer = $server;
 237                 $this->mUser = $user;
 238                 $this->mPassword = $password;
 239                 $this->mDBname = $dbName;
 240
 241                 $success = false;
 242
 243                 if ( $this->mFlags & DBO_PERSISTENT ) {
 244                         @/**/$this->mConn = mysql_pconnect( $server, $user, $password );
 245                 } else {
 246                         # Create a new connection...
 247                         if( version_compare( PHP_VERSION, '4.2.0', 'ge' ) ) {
 248                                 @/**/$this->mConn = mysql_connect( $server, $user, $password, true );
 249                         } else {
 250                                 # On PHP 4.1 the new_link parameter is not available. We cannot
 251                                 # guarantee that we'll actually get a new connection, and this
 252                                 # may cause some operations to fail possibly.
 253                                 @/**/$this->mConn = mysql_connect( $server, $user, $password );
 254                         }
 255                 }
 256
 257                 if ( $dbName != '' ) {
 258                         if ( $this->mConn !== false ) {
 259                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 260                                 if ( !$success ) {
 261                                         wfDebug( "Error selecting database \"$dbName\": " . $this->lastError() . "\n" );
 262                                 }
 263                         } else {
 264                                 wfDebug( "DB connection error\n" );
 265                                 wfDebug( "Server: $server, User: $user, Password: " .
 266                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 267                                 $success = false;
 268                         }
 269                 } else {
 270                         # Delay USE query
 271                         $success = (bool)$this->mConn;
 272                 }
 273
 274                 if ( !$success ) {
 275                         $this->reportConnectionError();
 276                 }
 277                 $this->mOpened = $success;
 278                 return $success;
 279         }
 280         /**#@-*/
 281
 282         /**
 283          * Closes a database connection.
 284          * if it is open : commits any open transactions
 285          *
 286          * @return bool operation success. true if already closed.
 287          */
 288         function close()
 289         {
 290                 $this->mOpened = false;
 291                 if ( $this->mConn ) {
 292                         if ( $this->trxLevel() ) {
 293                                 $this->immediateCommit();
 294                         }
 295                         return mysql_close( $this->mConn );
 296                 } else {
 297                         return true;
 298                 }
 299         }
 300
 301         /**
 302          * @access private
 303          * @param string $msg error message ?
 304          */
 305         function reportConnectionError() {
 306                 if ( $this->mFailFunction ) {
 307                         if ( !is_int( $this->mFailFunction ) ) {
 308                                 $ff = $this->mFailFunction;
 309                                 $ff( $this, $this->lastError() );
 310                         }
 311                 } else {
 312                         wfEmergencyAbort( $this, $this->lastError() );
 313                 }
 314         }
 315
 316         /**
 317          * Usually aborts on failure
 318          * If errors are explicitly ignored, returns success
 319          */
 320         function query( $sql, $fname = '', $tempIgnore = false ) {
 321                 global $wgProfiling, $wgCommandLineMode;
 322
 323                 if ( wfReadOnly() ) {
 324                         # This is a quick check for the most common kinds of write query used
 325                         # in MediaWiki, to provide extra safety in addition to UI-level checks.
 326                         # It is not intended to prevent every conceivable write query, or even
 327                         # to handle such queries gracefully.
 328                         if ( preg_match( '/^(update|insert|replace|delete)/i', $sql ) ) {
 329                                 wfDebug( "Write query from $fname blocked\n" );
 330                                 return false;
 331                         }
 332                 }
 333
 334                 if ( $wgProfiling ) {
 335                         # generalizeSQL will probably cut down the query to reasonable
 336                         # logging size most of the time. The substr is really just a sanity check.
 337                         $profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 338                         wfProfileIn( 'Database::query' );
 339                         wfProfileIn( $profName );
 340                 }
 341
 342                 $this->mLastQuery = $sql;
 343
 344                 # Add a comment for easy SHOW PROCESSLIST interpretation
 345                 if ( $fname ) {
 346                         $commentedSql = "/* $fname */ $sql";
 347                 } else {
 348                         $commentedSql = $sql;
 349                 }
 350
 351                 # If DBO_TRX is set, start a transaction
 352                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 353                         $this->begin();
 354                 }
 355
 356                 if ( $this->debug() ) {
 357                         $sqlx = substr( $commentedSql, 0, 500 );
 358                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 359                         wfDebug( "SQL: $sqlx\n" );
 360                 }
 361
 362                 # Do the query and handle errors
 363                 $ret = $this->doQuery( $commentedSql );
 364
 365                 # Try reconnecting if the connection was lost
 366                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 367                         # Transaction is gone, like it or not
 368                         $this->mTrxLevel = 0;
 369                         wfDebug( "Connection lost, reconnecting...\n" );
 370                         if ( $this->ping() ) {
 371                                 wfDebug( "Reconnected\n" );
 372                                 $ret = $this->doQuery( $commentedSql );
 373                         } else {
 374                                 wfDebug( "Failed\n" );
 375                         }
 376                 }
 377
 378                 if ( false === $ret ) {
 379                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 380                 }
 381
 382                 if ( $wgProfiling ) {
 383                         wfProfileOut( $profName );
 384                         wfProfileOut( 'Database::query' );
 385                 }
 386                 return $ret;
 387         }
 388
 389         /**
 390          * The DBMS-dependent part of query()
 391          * @param string $sql SQL query.
 392          */
 393         function doQuery( $sql ) {
 394                 if( $this->bufferResults() ) {
 395                         $ret = mysql_query( $sql, $this->mConn );
 396                 } else {
 397                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 398                 }
 399                 return $ret;
 400         }
 401
 402         /**
 403          * @param $error
 404          * @param $errno
 405          * @param $sql
 406          * @param string $fname
 407          * @param bool $tempIgnore
 408          */
 409         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 410                 global $wgCommandLineMode, $wgFullyInitialised;
 411                 # Ignore errors during error handling to avoid infinite recursion
 412                 $ignore = $this->ignoreErrors( true );
 413                 $this->mErrorCount ++;
 414
 415                 if( $ignore || $tempIgnore ) {
 416                         wfDebug("SQL ERROR (ignored): " . $error . "\n");
 417                 } else {
 418                         $sql1line = str_replace( "\n", "\\n", $sql );
 419                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 420                         wfDebug("SQL ERROR: " . $error . "\n");
 421                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 422                                 $message = "A database error has occurred\n" .
 423                                   "Query: $sql\n" .
 424                                   "Function: $fname\n" .
 425                                   "Error: $errno $error\n";
 426                                 if ( !$wgCommandLineMode ) {
 427                                         $message = nl2br( $message );
 428                                 }
 429                                 wfDebugDieBacktrace( $message );
 430                         } else {
 431                                 // this calls wfAbruptExit()
 432                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 433                         }
 434                 }
 435                 $this->ignoreErrors( $ignore );
 436         }
 437
 438
 439         /**
 440          * Intended to be compatible with the PEAR::DB wrapper functions.
 441          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 442          *
 443          * ? = scalar value, quoted as necessary
 444          * ! = raw SQL bit (a function for instance)
 445          * & = filename; reads the file and inserts as a blob
 446          *     (we don't use this though...)
 447          */
 448         function prepare( $sql, $func = 'Database::prepare' ) {
 449                 /* MySQL doesn't support prepared statements (yet), so just
 450                    pack up the query for reference. We'll manually replace
 451                    the bits later. */
 452                 return array( 'query' => $sql, 'func' => $func );
 453         }
 454
 455         function freePrepared( $prepared ) {
 456                 /* No-op for MySQL */
 457         }
 458
 459         /**
 460          * Execute a prepared query with the various arguments
 461          * @param string $prepared the prepared sql
 462          * @param mixed $args Either an array here, or put scalars as varargs
 463          */
 464         function execute( $prepared, $args = null ) {
 465                 if( !is_array( $args ) ) {
 466                         # Pull the var args
 467                         $args = func_get_args();
 468                         array_shift( $args );
 469                 }
 470                 $sql = $this->fillPrepared( $prepared['query'], $args );
 471                 return $this->query( $sql, $prepared['func'] );
 472         }
 473
 474         /**
 475          * Prepare & execute an SQL statement, quoting and inserting arguments
 476          * in the appropriate places.
 477          * @param string $query
 478          * @param string $args ...
 479          */
 480         function safeQuery( $query, $args = null ) {
 481                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 482                 if( !is_array( $args ) ) {
 483                         # Pull the var args
 484                         $args = func_get_args();
 485                         array_shift( $args );
 486                 }
 487                 $retval = $this->execute( $prepared, $args );
 488                 $this->freePrepared( $prepared );
 489                 return $retval;
 490         }
 491
 492         /**
 493          * For faking prepared SQL statements on DBs that don't support
 494          * it directly.
 495          * @param string $preparedSql - a 'preparable' SQL statement
 496          * @param array $args - array of arguments to fill it with
 497          * @return string executable SQL
 498          */
 499         function fillPrepared( $preparedQuery, $args ) {
 500                 $n = 0;
 501                 reset( $args );
 502                 $this->preparedArgs =& $args;
 503                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 504                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 505         }
 506
 507         /**
 508          * preg_callback func for fillPrepared()
 509          * The arguments should be in $this->preparedArgs and must not be touched
 510          * while we're doing this.
 511          *
 512          * @param array $matches
 513          * @return string
 514          * @access private
 515          */
 516         function fillPreparedArg( $matches ) {
 517                 switch( $matches[1] ) {
 518                         case '\\?': return '?';
 519                         case '\\!': return '!';
 520                         case '\\&': return '&';
 521                 }
 522                 list( $n, $arg ) = each( $this->preparedArgs );
 523                 switch( $matches[1] ) {
 524                         case '?': return $this->addQuotes( $arg );
 525                         case '!': return $arg;
 526                         case '&':
 527                                 # return $this->addQuotes( file_get_contents( $arg ) );
 528                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 529                         default:
 530                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 531                 }
 532         }
 533
 534         /**#@+
 535          * @param mixed $res A SQL result
 536          */
 537         /**
 538          * Free a result object
 539          */
 540         function freeResult( $res ) {
 541                 if ( !@/**/mysql_free_result( $res ) ) {
 542                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 543                 }
 544         }
 545
 546         /**
 547          * Fetch the next row from the given result object, in object form
 548          */
 549         function fetchObject( $res ) {
 550                 @/**/$row = mysql_fetch_object( $res );
 551                 if( mysql_errno() ) {
 552                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 553                 }
 554                 return $row;
 555         }
 556
 557         /**
 558          * Fetch the next row from the given result object
 559          * Returns an array
 560          */
 561         function fetchRow( $res ) {
 562                 @/**/$row = mysql_fetch_array( $res );
 563                 if (mysql_errno() ) {
 564                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 565                 }
 566                 return $row;
 567         }
 568
 569         /**
 570          * Get the number of rows in a result object
 571          */
 572         function numRows( $res ) {
 573                 @/**/$n = mysql_num_rows( $res );
 574                 if( mysql_errno() ) {
 575                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 576                 }
 577                 return $n;
 578         }
 579
 580         /**
 581          * Get the number of fields in a result object
 582          * See documentation for mysql_num_fields()
 583          */
 584         function numFields( $res ) { return mysql_num_fields( $res ); }
 585
 586         /**
 587          * Get a field name in a result object
 588          * See documentation for mysql_field_name()
 589          */
 590         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 591
 592         /**
 593          * Get the inserted value of an auto-increment row
 594          *
 595          * The value inserted should be fetched from nextSequenceValue()
 596          *
 597          * Example:
 598          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 599          * $dbw->insert('page',array('page_id' => $id));
 600          * $id = $dbw->insertId();
 601          */
 602         function insertId() { return mysql_insert_id( $this->mConn ); }
 603
 604         /**
 605          * Change the position of the cursor in a result object
 606          * See mysql_data_seek()
 607          */
 608         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 609
 610         /**
 611          * Get the last error number
 612          * See mysql_errno()
 613          */
 614         function lastErrno() {
 615                 if ( $this->mConn ) {
 616                         return mysql_errno( $this->mConn );
 617                 } else {
 618                         return mysql_errno();
 619                 }
 620         }
 621
 622         /**
 623          * Get a description of the last error
 624          * See mysql_error() for more details
 625          */
 626         function lastError() {
 627                 if ( $this->mConn ) {
 628                         # Even if it's non-zero, it can still be invalid
 629                         wfSuppressWarnings();
 630                         $error = mysql_error( $this->mConn );
 631                         if ( !$error ) {
 632                                 $error = mysql_error();
 633                         }
 634                         wfRestoreWarnings();
 635                 } else {
 636                         $error = mysql_error();
 637                 }
 638                 if( $error ) {
 639                         $error .= ' (' . $this->mServer . ')';
 640                 }
 641                 return $error;
 642         }
 643         /**
 644          * Get the number of rows affected by the last write query
 645          * See mysql_affected_rows() for more details
 646          */
 647         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 648         /**#@-*/ // end of template : @param $result
 649
 650         /**
 651          * Simple UPDATE wrapper
 652          * Usually aborts on failure
 653          * If errors are explicitly ignored, returns success
 654          *
 655          * This function exists for historical reasons, Database::update() has a more standard
 656          * calling convention and feature set
 657          */
 658         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 659         {
 660                 $table = $this->tableName( $table );
 661                 $sql = "UPDATE $table SET $var = '" .
 662                   $this->strencode( $value ) . "' WHERE ($cond)";
 663                 return (bool)$this->query( $sql, DB_MASTER, $fname );
 664         }
 665
 666         /**
 667          * Simple SELECT wrapper, returns a single field, input must be encoded
 668          * Usually aborts on failure
 669          * If errors are explicitly ignored, returns FALSE on failure
 670          */
 671         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 672                 if ( !is_array( $options ) ) {
 673                         $options = array( $options );
 674                 }
 675                 $options['LIMIT'] = 1;
 676
 677                 $res = $this->select( $table, $var, $cond, $fname, $options );
 678                 if ( $res === false || !$this->numRows( $res ) ) {
 679                         return false;
 680                 }
 681                 $row = $this->fetchRow( $res );
 682                 if ( $row !== false ) {
 683                         $this->freeResult( $res );
 684                         return $row[0];
 685                 } else {
 686                         return false;
 687                 }
 688         }
 689
 690         /**
 691          * Returns an optional USE INDEX clause to go after the table, and a
 692          * string to go at the end of the query
 693          *
 694          * @access private
 695          *
 696          * @param array $options an associative array of options to be turned into
 697          *              an SQL query, valid keys are listed in the function.
 698          * @return array
 699          */
 700         function makeSelectOptions( $options ) {
 701                 $tailOpts = '';
 702
 703                 if ( isset( $options['GROUP BY'] ) ) {
 704                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 705                 }
 706                 if ( isset( $options['ORDER BY'] ) ) {
 707                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 708                 }
 709                 if (isset($options['LIMIT'])) {
 710                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 711                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 712                 }
 713                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 714                         $tailOpts .= ' FOR UPDATE';
 715                 }
 716
 717                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 718                         $tailOpts .= ' LOCK IN SHARE MODE';
 719                 }
 720
 721                 if ( isset( $options['USE INDEX'] ) ) {
 722                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 723                 } else {
 724                         $useIndex = '';
 725                 }
 726                 return array( $useIndex, $tailOpts );
 727         }
 728
 729         /**
 730          * SELECT wrapper
 731          */
 732         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 733         {
 734                 if( is_array( $vars ) ) {
 735                         $vars = implode( ',', $vars );
 736                 }
 737                 if( !is_array( $options ) ) {
 738                         $options = array( $options );
 739                 }
 740                 if( is_array( $table ) ) {
 741                         $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 742                 } elseif ($table!='') {
 743                         $from = ' FROM ' .$this->tableName( $table );
 744                 } else {
 745                         $from = '';
 746                 }
 747
 748                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 749
 750                 if( !empty( $conds ) ) {
 751                         if ( is_array( $conds ) ) {
 752                                 $conds = $this->makeList( $conds, LIST_AND );
 753                         }
 754                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 755                 } else {
 756                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 757                 }
 758
 759                 return $this->query( $sql, $fname );
 760         }
 761
 762         /**
 763          * Single row SELECT wrapper
 764          * Aborts or returns FALSE on error
 765          *
 766          * $vars: the selected variables
 767          * $conds: a condition map, terms are ANDed together.
 768          *   Items with numeric keys are taken to be literal conditions
 769          * Takes an array of selected variables, and a condition map, which is ANDed
 770          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 771          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 772          * $obj- >page_id is the ID of the Astronomy article
 773          *
 774          * @todo migrate documentation to phpdocumentor format
 775          */
 776         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 777                 $options['LIMIT'] = 1;
 778                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 779                 if ( $res === false )
 780                         return false;
 781                 if ( !$this->numRows($res) ) {
 782                         $this->freeResult($res);
 783                         return false;
 784                 }
 785                 $obj = $this->fetchObject( $res );
 786                 $this->freeResult( $res );
 787                 return $obj;
 788
 789         }
 790
 791         /**
 792          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 793          * It's only slightly flawed. Don't use for anything important.
 794          *
 795          * @param string $sql A SQL Query
 796          * @static
 797          */
 798         function generalizeSQL( $sql ) {
 799                 # This does the same as the regexp below would do, but in such a way
 800                 # as to avoid crashing php on some large strings.
 801                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 802
 803                 $sql = str_replace ( "\\\\", '', $sql);
 804                 $sql = str_replace ( "\\'", '', $sql);
 805                 $sql = str_replace ( "\\\"", '', $sql);
 806                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 807                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 808
 809                 # All newlines, tabs, etc replaced by single space
 810                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 811
 812                 # All numbers => N
 813                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 814
 815                 return $sql;
 816         }
 817
 818         /**
 819          * Determines whether a field exists in a table
 820          * Usually aborts on failure
 821          * If errors are explicitly ignored, returns NULL on failure
 822          */
 823         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 824                 $table = $this->tableName( $table );
 825                 $res = $this->query( 'DESCRIBE '.$table, DB_SLAVE, $fname );
 826                 if ( !$res ) {
 827                         return NULL;
 828                 }
 829
 830                 $found = false;
 831
 832                 while ( $row = $this->fetchObject( $res ) ) {
 833                         if ( $row->Field == $field ) {
 834                                 $found = true;
 835                                 break;
 836                         }
 837                 }
 838                 return $found;
 839         }
 840
 841         /**
 842          * Determines whether an index exists
 843          * Usually aborts on failure
 844          * If errors are explicitly ignored, returns NULL on failure
 845          */
 846         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 847                 $info = $this->indexInfo( $table, $index, $fname );
 848                 if ( is_null( $info ) ) {
 849                         return NULL;
 850                 } else {
 851                         return $info !== false;
 852                 }
 853         }
 854
 855
 856         /**
 857          * Get information about an index into an object
 858          * Returns false if the index does not exist
 859          */
 860         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 861                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 862                 # SHOW INDEX should work for 3.x and up:
 863                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 864                 $table = $this->tableName( $table );
 865                 $sql = 'SHOW INDEX FROM '.$table;
 866                 $res = $this->query( $sql, $fname );
 867                 if ( !$res ) {
 868                         return NULL;
 869                 }
 870
 871                 while ( $row = $this->fetchObject( $res ) ) {
 872                         if ( $row->Key_name == $index ) {
 873                                 return $row;
 874                         }
 875                 }
 876                 return false;
 877         }
 878
 879         /**
 880          * Query whether a given table exists
 881          */
 882         function tableExists( $table ) {
 883                 $table = $this->tableName( $table );
 884                 $old = $this->ignoreErrors( true );
 885                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 886                 $this->ignoreErrors( $old );
 887                 if( $res ) {
 888                         $this->freeResult( $res );
 889                         return true;
 890                 } else {
 891                         return false;
 892                 }
 893         }
 894
 895         /**
 896          * mysql_fetch_field() wrapper
 897          * Returns false if the field doesn't exist
 898          *
 899          * @param $table
 900          * @param $field
 901          */
 902         function fieldInfo( $table, $field ) {
 903                 $table = $this->tableName( $table );
 904                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 905                 $n = mysql_num_fields( $res );
 906                 for( $i = 0; $i < $n; $i++ ) {
 907                         $meta = mysql_fetch_field( $res, $i );
 908                         if( $field == $meta->name ) {
 909                                 return $meta;
 910                         }
 911                 }
 912                 return false;
 913         }
 914
 915         /**
 916          * mysql_field_type() wrapper
 917          */
 918         function fieldType( $res, $index ) {
 919                 return mysql_field_type( $res, $index );
 920         }
 921
 922         /**
 923          * Determines if a given index is unique
 924          */
 925         function indexUnique( $table, $index ) {
 926                 $indexInfo = $this->indexInfo( $table, $index );
 927                 if ( !$indexInfo ) {
 928                         return NULL;
 929                 }
 930                 return !$indexInfo->Non_unique;
 931         }
 932
 933         /**
 934          * INSERT wrapper, inserts an array into a table
 935          *
 936          * $a may be a single associative array, or an array of these with numeric keys, for
 937          * multi-row insert.
 938          *
 939          * Usually aborts on failure
 940          * If errors are explicitly ignored, returns success
 941          */
 942         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 943                 # No rows to insert, easy just return now
 944                 if ( !count( $a ) ) {
 945                         return true;
 946                 }
 947
 948                 $table = $this->tableName( $table );
 949                 if ( !is_array( $options ) ) {
 950                         $options = array( $options );
 951                 }
 952                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
 953                         $multi = true;
 954                         $keys = array_keys( $a[0] );
 955                 } else {
 956                         $multi = false;
 957                         $keys = array_keys( $a );
 958                 }
 959
 960                 $sql = 'INSERT ' . implode( ' ', $options ) .
 961                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 962
 963                 if ( $multi ) {
 964                         $first = true;
 965                         foreach ( $a as $row ) {
 966                                 if ( $first ) {
 967                                         $first = false;
 968                                 } else {
 969                                         $sql .= ',';
 970                                 }
 971                                 $sql .= '(' . $this->makeList( $row ) . ')';
 972                         }
 973                 } else {
 974                         $sql .= '(' . $this->makeList( $a ) . ')';
 975                 }
 976                 return (bool)$this->query( $sql, $fname );
 977         }
 978
 979         /**
 980          * Make UPDATE options for the Database::update function
 981          *
 982          * @access private
 983          * @param array $options The options passed to Database::update
 984          * @return string
 985          */
 986         function makeUpdateOptions( $options ) {
 987                 if( !is_array( $options ) ) {
 988                         $options = array( $options );
 989                 }
 990                 $opts = array();
 991                 if ( in_array( 'LOW_PRIORITY', $options ) )
 992                         $opts[] = $this->lowPriorityOption();
 993                 if ( in_array( 'IGNORE', $options ) )
 994                         $opts[] = 'IGNORE';
 995                 return implode(' ', $opts);
 996         }
 997
 998         /**
 999          * UPDATE wrapper, takes a condition array and a SET array
1000          *
1001          * @param string $table  The table to UPDATE
1002          * @param array  $values An array of values to SET
1003          * @param array  $conds  An array of conditions (WHERE)
1004          * @param string $fname  The Class::Function calling this function
1005          *                       (for the log)
1006          * @param array  $options An array of UPDATE options, can be one or
1007          *                        more of IGNORE, LOW_PRIORITY
1008          */
1009         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1010                 $table = $this->tableName( $table );
1011                 $opts = $this->makeUpdateOptions( $options );
1012                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1013                 if ( $conds != '*' ) {
1014                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1015                 }
1016                 $this->query( $sql, $fname );
1017         }
1018
1019         /**
1020          * Makes a wfStrencoded list from an array
1021          * $mode: LIST_COMMA         - comma separated, no field names
1022          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1023          *        LIST_SET           - comma separated with field names, like a SET clause
1024          *        LIST_NAMES         - comma separated field names
1025          */
1026         function makeList( $a, $mode = LIST_COMMA ) {
1027                 if ( !is_array( $a ) ) {
1028                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1029                 }
1030
1031                 $first = true;
1032                 $list = '';
1033                 foreach ( $a as $field => $value ) {
1034                         if ( !$first ) {
1035                                 if ( $mode == LIST_AND ) {
1036                                         $list .= ' AND ';
1037                                 } elseif($mode == LIST_OR) {
1038                                         $list .= ' OR ';
1039                                 } else {
1040                                         $list .= ',';
1041                                 }
1042                         } else {
1043                                 $first = false;
1044                         }
1045                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1046                                 $list .= "($value)";
1047                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1048                                 $list .= $field." IN (".$this->makeList($value).") ";
1049                         } else {
1050                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1051                                         $list .= "$field = ";
1052                                 }
1053                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1054                         }
1055                 }
1056                 return $list;
1057         }
1058
1059         /**
1060          * Change the current database
1061          */
1062         function selectDB( $db ) {
1063                 $this->mDBname = $db;
1064                 return mysql_select_db( $db, $this->mConn );
1065         }
1066
1067         /**
1068          * Starts a timer which will kill the DB thread after $timeout seconds
1069          */
1070         function startTimer( $timeout ) {
1071                 global $IP;
1072                 if( function_exists( 'mysql_thread_id' ) ) {
1073                         # This will kill the query if it's still running after $timeout seconds.
1074                         $tid = mysql_thread_id( $this->mConn );
1075                         exec( "php $IP/includes/killthread.php $timeout $tid &>/dev/null &" );
1076                 }
1077         }
1078
1079         /**
1080          * Stop a timer started by startTimer()
1081          * Currently unimplemented.
1082          *
1083          */
1084         function stopTimer() { }
1085
1086         /**
1087          * Format a table name ready for use in constructing an SQL query
1088          *
1089          * This does two important things: it quotes table names which as necessary,
1090          * and it adds a table prefix if there is one.
1091          *
1092          * All functions of this object which require a table name call this function
1093          * themselves. Pass the canonical name to such functions. This is only needed
1094          * when calling query() directly.
1095          *
1096          * @param string $name database table name
1097          */
1098         function tableName( $name ) {
1099                 global $wgSharedDB;
1100                 # Skip quoted literals
1101                 if ( $name{0} != '`' ) {
1102                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1103                                 $name = "{$this->mTablePrefix}$name";
1104                         }
1105                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1106                                 $name = "`$wgSharedDB`.`$name`";
1107                         } else {
1108                                 # Standard quoting
1109                                 $name = "`$name`";
1110                         }
1111                 }
1112                 return $name;
1113         }
1114
1115         /**
1116          * Fetch a number of table names into an array
1117          * This is handy when you need to construct SQL for joins
1118          *
1119          * Example:
1120          * extract($dbr->tableNames('user','watchlist'));
1121          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1122          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1123          */
1124         function tableNames() {
1125                 $inArray = func_get_args();
1126                 $retVal = array();
1127                 foreach ( $inArray as $name ) {
1128                         $retVal[$name] = $this->tableName( $name );
1129                 }
1130                 return $retVal;
1131         }
1132
1133         /**
1134          * Wrapper for addslashes()
1135          * @param string $s String to be slashed.
1136          * @return string slashed string.
1137          */
1138         function strencode( $s ) {
1139                 return addslashes( $s );
1140         }
1141
1142         /**
1143          * If it's a string, adds quotes and backslashes
1144          * Otherwise returns as-is
1145          */
1146         function addQuotes( $s ) {
1147                 if ( is_null( $s ) ) {
1148                         return 'NULL';
1149                 } else {
1150                         # This will also quote numeric values. This should be harmless,
1151                         # and protects against weird problems that occur when they really
1152                         # _are_ strings such as article titles and string->number->string
1153                         # conversion is not 1:1.
1154                         return "'" . $this->strencode( $s ) . "'";
1155                 }
1156         }
1157
1158         /**
1159          * Escape string for safe LIKE usage
1160          */
1161         function escapeLike( $s ) {
1162                 $s=$this->strencode( $s );
1163                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1164                 return $s;
1165         }
1166
1167         /**
1168          * Returns an appropriately quoted sequence value for inserting a new row.
1169          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1170          * subclass will return an integer, and save the value for insertId()
1171          */
1172         function nextSequenceValue( $seqName ) {
1173                 return NULL;
1174         }
1175
1176         /**
1177          * USE INDEX clause
1178          * PostgreSQL doesn't have them and returns ""
1179          */
1180         function useIndexClause( $index ) {
1181                 global $wgDBmysql4;
1182                 return $wgDBmysql4
1183                         ? "FORCE INDEX ($index)"
1184                         : "USE INDEX ($index)";
1185         }
1186
1187         /**
1188          * REPLACE query wrapper
1189          * PostgreSQL simulates this with a DELETE followed by INSERT
1190          * $row is the row to insert, an associative array
1191          * $uniqueIndexes is an array of indexes. Each element may be either a
1192          * field name or an array of field names
1193          *
1194          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1195          * However if you do this, you run the risk of encountering errors which wouldn't have
1196          * occurred in MySQL
1197          *
1198          * @todo migrate comment to phodocumentor format
1199          */
1200         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1201                 $table = $this->tableName( $table );
1202
1203                 # Single row case
1204                 if ( !is_array( reset( $rows ) ) ) {
1205                         $rows = array( $rows );
1206                 }
1207
1208                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1209                 $first = true;
1210                 foreach ( $rows as $row ) {
1211                         if ( $first ) {
1212                                 $first = false;
1213                         } else {
1214                                 $sql .= ',';
1215                         }
1216                         $sql .= '(' . $this->makeList( $row ) . ')';
1217                 }
1218                 return $this->query( $sql, $fname );
1219         }
1220
1221         /**
1222          * DELETE where the condition is a join
1223          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1224          *
1225          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1226          * join condition matches, set $conds='*'
1227          *
1228          * DO NOT put the join condition in $conds
1229          *
1230          * @param string $delTable The table to delete from.
1231          * @param string $joinTable The other table.
1232          * @param string $delVar The variable to join on, in the first table.
1233          * @param string $joinVar The variable to join on, in the second table.
1234          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1235          */
1236         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1237                 if ( !$conds ) {
1238                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1239                 }
1240
1241                 $delTable = $this->tableName( $delTable );
1242                 $joinTable = $this->tableName( $joinTable );
1243                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1244                 if ( $conds != '*' ) {
1245                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1246                 }
1247
1248                 return $this->query( $sql, $fname );
1249         }
1250
1251         /**
1252          * Returns the size of a text field, or -1 for "unlimited"
1253          */
1254         function textFieldSize( $table, $field ) {
1255                 $table = $this->tableName( $table );
1256                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1257                 $res = $this->query( $sql, 'Database::textFieldSize' );
1258                 $row = $this->fetchObject( $res );
1259                 $this->freeResult( $res );
1260
1261                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1262                         $size = $m[1];
1263                 } else {
1264                         $size = -1;
1265                 }
1266                 return $size;
1267         }
1268
1269         /**
1270          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1271          */
1272         function lowPriorityOption() {
1273                 return 'LOW_PRIORITY';
1274         }
1275
1276         /**
1277          * DELETE query wrapper
1278          *
1279          * Use $conds == "*" to delete all rows
1280          */
1281         function delete( $table, $conds, $fname = 'Database::delete' ) {
1282                 if ( !$conds ) {
1283                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1284                 }
1285                 $table = $this->tableName( $table );
1286                 $sql = "DELETE FROM $table";
1287                 if ( $conds != '*' ) {
1288                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1289                 }
1290                 return $this->query( $sql, $fname );
1291         }
1292
1293         /**
1294          * INSERT SELECT wrapper
1295          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1296          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1297          * $conds may be "*" to copy the whole table
1298          * srcTable may be an array of tables.
1299          */
1300         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect' ) {
1301                 $destTable = $this->tableName( $destTable );
1302                 if( is_array( $srcTable ) ) {
1303                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1304                 } else {
1305                         $srcTable = $this->tableName( $srcTable );
1306                 }
1307                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1308                         ' SELECT ' . implode( ',', $varMap ) .
1309                         " FROM $srcTable";
1310                 if ( $conds != '*' ) {
1311                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1312                 }
1313                 return $this->query( $sql, $fname );
1314         }
1315
1316         /**
1317          * Construct a LIMIT query with optional offset
1318          * This is used for query pages
1319          * $sql string SQL query we will append the limit too
1320          * $limit integer the SQL limit
1321          * $offset integer the SQL offset (default false)
1322          */
1323         function limitResult($sql, $limit, $offset=false) {
1324                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1325         }
1326         function limitResultForUpdate($sql, $num) {
1327                 return $this->limitResult($sql, $num, 0);
1328         }
1329
1330         /**
1331          * Returns an SQL expression for a simple conditional.
1332          * Uses IF on MySQL.
1333          *
1334          * @param string $cond SQL expression which will result in a boolean value
1335          * @param string $trueVal SQL expression to return if true
1336          * @param string $falseVal SQL expression to return if false
1337          * @return string SQL fragment
1338          */
1339         function conditional( $cond, $trueVal, $falseVal ) {
1340                 return " IF($cond, $trueVal, $falseVal) ";
1341         }
1342
1343         /**
1344          * Determines if the last failure was due to a deadlock
1345          */
1346         function wasDeadlock() {
1347                 return $this->lastErrno() == 1213;
1348         }
1349
1350         /**
1351          * Perform a deadlock-prone transaction.
1352          *
1353          * This function invokes a callback function to perform a set of write
1354          * queries. If a deadlock occurs during the processing, the transaction
1355          * will be rolled back and the callback function will be called again.
1356          *
1357          * Usage:
1358          *   $dbw->deadlockLoop( callback, ... );
1359          *
1360          * Extra arguments are passed through to the specified callback function.
1361          *
1362          * Returns whatever the callback function returned on its successful,
1363          * iteration, or false on error, for example if the retry limit was
1364          * reached.
1365          */
1366         function deadlockLoop() {
1367                 $myFname = 'Database::deadlockLoop';
1368
1369                 $this->begin();
1370                 $args = func_get_args();
1371                 $function = array_shift( $args );
1372                 $oldIgnore = $this->ignoreErrors( true );
1373                 $tries = DEADLOCK_TRIES;
1374                 if ( is_array( $function ) ) {
1375                         $fname = $function[0];
1376                 } else {
1377                         $fname = $function;
1378                 }
1379                 do {
1380                         $retVal = call_user_func_array( $function, $args );
1381                         $error = $this->lastError();
1382                         $errno = $this->lastErrno();
1383                         $sql = $this->lastQuery();
1384
1385                         if ( $errno ) {
1386                                 if ( $this->wasDeadlock() ) {
1387                                         # Retry
1388                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1389                                 } else {
1390                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1391                                 }
1392                         }
1393                 } while( $this->wasDeadlock() && --$tries > 0 );
1394                 $this->ignoreErrors( $oldIgnore );
1395                 if ( $tries <= 0 ) {
1396                         $this->query( 'ROLLBACK', $myFname );
1397                         $this->reportQueryError( $error, $errno, $sql, $fname );
1398                         return false;
1399                 } else {
1400                         $this->query( 'COMMIT', $myFname );
1401                         return $retVal;
1402                 }
1403         }
1404
1405         /**
1406          * Do a SELECT MASTER_POS_WAIT()
1407          *
1408          * @param string $file the binlog file
1409          * @param string $pos the binlog position
1410          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1411          */
1412         function masterPosWait( $file, $pos, $timeout ) {
1413                 $fname = 'Database::masterPosWait';
1414                 wfProfileIn( $fname );
1415
1416
1417                 # Commit any open transactions
1418                 $this->immediateCommit();
1419
1420                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1421                 $encFile = $this->strencode( $file );
1422                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1423                 $res = $this->doQuery( $sql );
1424                 if ( $res && $row = $this->fetchRow( $res ) ) {
1425                         $this->freeResult( $res );
1426                         wfProfileOut( $fname );
1427                         return $row[0];
1428                 } else {
1429                         wfProfileOut( $fname );
1430                         return false;
1431                 }
1432         }
1433
1434         /**
1435          * Get the position of the master from SHOW SLAVE STATUS
1436          */
1437         function getSlavePos() {
1438                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1439                 $row = $this->fetchObject( $res );
1440                 if ( $row ) {
1441                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1442                 } else {
1443                         return array( false, false );
1444                 }
1445         }
1446
1447         /**
1448          * Get the position of the master from SHOW MASTER STATUS
1449          */
1450         function getMasterPos() {
1451                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1452                 $row = $this->fetchObject( $res );
1453                 if ( $row ) {
1454                         return array( $row->File, $row->Position );
1455                 } else {
1456                         return array( false, false );
1457                 }
1458         }
1459
1460         /**
1461          * Begin a transaction, or if a transaction has already started, continue it
1462          */
1463         function begin( $fname = 'Database::begin' ) {
1464                 if ( !$this->mTrxLevel ) {
1465                         $this->immediateBegin( $fname );
1466                 } else {
1467                         $this->mTrxLevel++;
1468                 }
1469         }
1470
1471         /**
1472          * End a transaction, or decrement the nest level if transactions are nested
1473          */
1474         function commit( $fname = 'Database::commit' ) {
1475                 if ( $this->mTrxLevel ) {
1476                         $this->mTrxLevel--;
1477                 }
1478                 if ( !$this->mTrxLevel ) {
1479                         $this->immediateCommit( $fname );
1480                 }
1481         }
1482
1483         /**
1484          * Rollback a transaction
1485          */
1486         function rollback( $fname = 'Database::rollback' ) {
1487                 $this->query( 'ROLLBACK', $fname );
1488                 $this->mTrxLevel = 0;
1489         }
1490
1491         /**
1492          * Begin a transaction, committing any previously open transaction
1493          */
1494         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1495                 $this->query( 'BEGIN', $fname );
1496                 $this->mTrxLevel = 1;
1497         }
1498
1499         /**
1500          * Commit transaction, if one is open
1501          */
1502         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1503                 $this->query( 'COMMIT', $fname );
1504                 $this->mTrxLevel = 0;
1505         }
1506
1507         /**
1508          * Return MW-style timestamp used for MySQL schema
1509          */
1510         function timestamp( $ts=0 ) {
1511                 return wfTimestamp(TS_MW,$ts);
1512         }
1513
1514         /**
1515          * Local database timestamp format or null
1516          */
1517         function timestampOrNull( $ts = null ) {
1518                 if( is_null( $ts ) ) {
1519                         return null;
1520                 } else {
1521                         return $this->timestamp( $ts );
1522                 }
1523         }
1524
1525         /**
1526          * @todo document
1527          */
1528         function resultObject( &$result ) {
1529                 if( empty( $result ) ) {
1530                         return NULL;
1531                 } else {
1532                         return new ResultWrapper( $this, $result );
1533                 }
1534         }
1535
1536         /**
1537          * Return aggregated value alias
1538          */
1539         function aggregateValue ($valuedata,$valuename='value') {
1540                 return $valuename;
1541         }
1542
1543         /**
1544          * @return string wikitext of a link to the server software's web site
1545          */
1546         function getSoftwareLink() {
1547                 return "[http://www.mysql.com/ MySQL]";
1548         }
1549
1550         /**
1551          * @return string Version information from the database
1552          */
1553         function getServerVersion() {
1554                 return mysql_get_server_info();
1555         }
1556
1557         /**
1558          * Ping the server and try to reconnect if it there is no connection
1559          */
1560         function ping() {
1561                 if( function_exists( 'mysql_ping' ) ) {
1562                         return mysql_ping( $this->mConn );
1563                 } else {
1564                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1565                         return true;
1566                 }
1567         }
1568
1569         /**
1570          * Get slave lag.
1571          * At the moment, this will only work if the DB user has the PROCESS privilege
1572          */
1573         function getLag() {
1574                 $res = $this->query( 'SHOW PROCESSLIST' );
1575                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1576                 # dubious, but unfortunately there's no easy rigorous way
1577                 $slaveThreads = 0;
1578                 while ( $row = $this->fetchObject( $res ) ) {
1579                         if ( $row->User == 'system user' ) {
1580                                 if ( ++$slaveThreads == 2 ) {
1581                                         # This is it, return the time
1582                                         return $row->Time;
1583                                 }
1584                         }
1585                 }
1586                 return false;
1587         }
1588
1589         /**
1590          * Get status information from SHOW STATUS in an associative array
1591          */
1592         function getStatus() {
1593                 $res = $this->query( 'SHOW STATUS' );
1594                 $status = array();
1595                 while ( $row = $this->fetchObject( $res ) ) {
1596                         $status[$row->Variable_name] = $row->Value;
1597                 }
1598                 return $status;
1599         }
1600
1601         /**
1602          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1603          */
1604         function maxListLen() {
1605                 return 0;
1606         }
1607
1608         function encodeBlob($b) {
1609                 return $b;
1610         }
1611
1612         function notNullTimestamp() {
1613                 return "!= 0";
1614         }
1615         function isNullTimestamp() {
1616                 return "= '0'";
1617         }
1618 }
1619
1620 /**
1621  * Database abstraction object for mySQL
1622  * Inherit all methods and properties of Database::Database()
1623  *
1624  * @package MediaWiki
1625  * @see Database
1626  */
1627 class DatabaseMysql extends Database {
1628         # Inherit all
1629 }
1630
1631
1632 /**
1633  * Result wrapper for grabbing data queried by someone else
1634  *
1635  * @package MediaWiki
1636  */
1637 class ResultWrapper {
1638         var $db, $result;
1639
1640         /**
1641          * @todo document
1642          */
1643         function ResultWrapper( $database, $result ) {
1644                 $this->db =& $database;
1645                 $this->result =& $result;
1646         }
1647
1648         /**
1649          * @todo document
1650          */
1651         function numRows() {
1652                 return $this->db->numRows( $this->result );
1653         }
1654
1655         /**
1656          * @todo document
1657          */
1658         function fetchObject() {
1659                 return $this->db->fetchObject( $this->result );
1660         }
1661
1662         /**
1663          * @todo document
1664          */
1665         function &fetchRow() {
1666                 return $this->db->fetchRow( $this->result );
1667         }
1668
1669         /**
1670          * @todo document
1671          */
1672         function free() {
1673                 $this->db->freeResult( $this->result );
1674                 unset( $this->result );
1675                 unset( $this->db );
1676         }
1677
1678         function seek( $row ) {
1679                 $this->db->dataSeek( $this->result, $row );
1680         }
1681 }
1682
1683 #------------------------------------------------------------------------------
1684 # Global functions
1685 #------------------------------------------------------------------------------
1686
1687 /**
1688  * Standard fail function, called by default when a connection cannot be
1689  * established.
1690  * Displays the file cache if possible
1691  */
1692 function wfEmergencyAbort( &$conn, $error ) {
1693         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1694         global $wgSitename, $wgServer, $wgMessageCache;
1695
1696         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1697         # Hard coding strings instead.
1698
1699         $noconnect = 'Sorry! The wiki is experiencing some technical difficulties, and cannot contact the database server: $1. <br />
1700 $1';
1701         $mainpage = 'Main Page';
1702         $searchdisabled = <<<EOT
1703 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1704 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1705 EOT;
1706
1707         $googlesearch = "
1708 <!-- SiteSearch Google -->
1709 <FORM method=GET action=\"http://www.google.com/search\">
1710 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1711 <A HREF=\"http://www.google.com/\">
1712 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1713 border=\"0\" ALT=\"Google\"></A>
1714 </td>
1715 <td>
1716 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1717 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1718 <font size=-1>
1719 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1720 <input type='hidden' name='ie' value='$2'>
1721 <input type='hidden' name='oe' value='$2'>
1722 </font>
1723 </td></tr></TABLE>
1724 </FORM>
1725 <!-- SiteSearch Google -->";
1726         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1727
1728
1729         if( !headers_sent() ) {
1730                 header( 'HTTP/1.0 500 Internal Server Error' );
1731                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1732                 /* Don't cache error pages!  They cause no end of trouble... */
1733                 header( 'Cache-control: none' );
1734                 header( 'Pragma: nocache' );
1735         }
1736
1737         # No database access
1738         if ( is_object( $wgMessageCache ) ) {
1739                 $wgMessageCache->disable();
1740         }
1741
1742         $msg = wfGetSiteNotice();
1743         if($msg == '') {
1744                 $msg = str_replace( '$1', $error, $noconnect );
1745         }
1746         $text = $msg;
1747
1748         if($wgUseFileCache) {
1749                 if($wgTitle) {
1750                         $t =& $wgTitle;
1751                 } else {
1752                         if($title) {
1753                                 $t = Title::newFromURL( $title );
1754                         } elseif (@/**/$_REQUEST['search']) {
1755                                 $search = $_REQUEST['search'];
1756                                 echo $searchdisabled;
1757                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1758                                   $wgInputEncoding ), $googlesearch );
1759                                 wfErrorExit();
1760                         } else {
1761                                 $t = Title::newFromText( $mainpage );
1762                         }
1763                 }
1764
1765                 $cache = new CacheManager( $t );
1766                 if( $cache->isFileCached() ) {
1767                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1768                                 $cachederror . "</b></p>\n";
1769
1770                         $tag = '<div id="article">';
1771                         $text = str_replace(
1772                                 $tag,
1773                                 $tag . $msg,
1774                                 $cache->fetchPageText() );
1775                 }
1776         }
1777
1778         echo $text;
1779         wfErrorExit();
1780 }
1781
1782 ?>