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
 278                 global $wgDBmysql5;
 279                 if( $wgDBmysql5 ) {
 280                         // Tell the server we're communicating with it in UTF-8.
 281                         // This may engage various charset conversions.
 282                         $this->query( 'SET NAMES utf8' );
 283                 }
 284
 285                 $this->mOpened = $success;
 286                 return $success;
 287         }
 288         /**#@-*/
 289
 290         /**
 291          * Closes a database connection.
 292          * if it is open : commits any open transactions
 293          *
 294          * @return bool operation success. true if already closed.
 295          */
 296         function close()
 297         {
 298                 $this->mOpened = false;
 299                 if ( $this->mConn ) {
 300                         if ( $this->trxLevel() ) {
 301                                 $this->immediateCommit();
 302                         }
 303                         return mysql_close( $this->mConn );
 304                 } else {
 305                         return true;
 306                 }
 307         }
 308
 309         /**
 310          * @access private
 311          * @param string $msg error message ?
 312          */
 313         function reportConnectionError() {
 314                 if ( $this->mFailFunction ) {
 315                         if ( !is_int( $this->mFailFunction ) ) {
 316                                 $ff = $this->mFailFunction;
 317                                 $ff( $this, $this->lastError() );
 318                         }
 319                 } else {
 320                         wfEmergencyAbort( $this, $this->lastError() );
 321                 }
 322         }
 323
 324         /**
 325          * Usually aborts on failure
 326          * If errors are explicitly ignored, returns success
 327          */
 328         function query( $sql, $fname = '', $tempIgnore = false ) {
 329                 global $wgProfiling, $wgCommandLineMode;
 330
 331                 if ( wfReadOnly() ) {
 332                         # This is a quick check for the most common kinds of write query used
 333                         # in MediaWiki, to provide extra safety in addition to UI-level checks.
 334                         # It is not intended to prevent every conceivable write query, or even
 335                         # to handle such queries gracefully.
 336                         if ( preg_match( '/^(?:update|insert|replace|delete)/i', $sql ) ) {
 337                                 wfDebug( "Write query from $fname blocked\n" );
 338                                 return false;
 339                         }
 340                 }
 341
 342                 if ( $wgProfiling ) {
 343                         # generalizeSQL will probably cut down the query to reasonable
 344                         # logging size most of the time. The substr is really just a sanity check.
 345
 346                         # Who's been wasting my precious column space? -- TS
 347                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 348                         $profName = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 349
 350                         wfProfileIn( 'Database::query' );
 351                         wfProfileIn( $profName );
 352                 }
 353
 354                 $this->mLastQuery = $sql;
 355
 356                 # Add a comment for easy SHOW PROCESSLIST interpretation
 357                 if ( $fname ) {
 358                         $commentedSql = "/* $fname */ $sql";
 359                 } else {
 360                         $commentedSql = $sql;
 361                 }
 362
 363                 # If DBO_TRX is set, start a transaction
 364                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 365                         $this->begin();
 366                 }
 367
 368                 if ( $this->debug() ) {
 369                         $sqlx = substr( $commentedSql, 0, 500 );
 370                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 371                         wfDebug( "SQL: $sqlx\n" );
 372                 }
 373
 374                 # Do the query and handle errors
 375                 $ret = $this->doQuery( $commentedSql );
 376
 377                 # Try reconnecting if the connection was lost
 378                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 379                         # Transaction is gone, like it or not
 380                         $this->mTrxLevel = 0;
 381                         wfDebug( "Connection lost, reconnecting...\n" );
 382                         if ( $this->ping() ) {
 383                                 wfDebug( "Reconnected\n" );
 384                                 $ret = $this->doQuery( $commentedSql );
 385                         } else {
 386                                 wfDebug( "Failed\n" );
 387                         }
 388                 }
 389
 390                 if ( false === $ret ) {
 391                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 392                 }
 393
 394                 if ( $wgProfiling ) {
 395                         wfProfileOut( $profName );
 396                         wfProfileOut( 'Database::query' );
 397                 }
 398                 return $ret;
 399         }
 400
 401         /**
 402          * The DBMS-dependent part of query()
 403          * @param string $sql SQL query.
 404          */
 405         function doQuery( $sql ) {
 406                 if( $this->bufferResults() ) {
 407                         $ret = mysql_query( $sql, $this->mConn );
 408                 } else {
 409                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 410                 }
 411                 return $ret;
 412         }
 413
 414         /**
 415          * @param $error
 416          * @param $errno
 417          * @param $sql
 418          * @param string $fname
 419          * @param bool $tempIgnore
 420          */
 421         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 422                 global $wgCommandLineMode, $wgFullyInitialised;
 423                 # Ignore errors during error handling to avoid infinite recursion
 424                 $ignore = $this->ignoreErrors( true );
 425                 ++$this->mErrorCount;
 426
 427                 if( $ignore || $tempIgnore ) {
 428                         wfDebug("SQL ERROR (ignored): $error\n");
 429                 } else {
 430                         $sql1line = str_replace( "\n", "\\n", $sql );
 431                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 432                         wfDebug("SQL ERROR: " . $error . "\n");
 433                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 434                                 $message = "A database error has occurred\n" .
 435                                   "Query: $sql\n" .
 436                                   "Function: $fname\n" .
 437                                   "Error: $errno $error\n";
 438                                 if ( !$wgCommandLineMode ) {
 439                                         $message = nl2br( $message );
 440                                 }
 441                                 wfDebugDieBacktrace( $message );
 442                         } else {
 443                                 // this calls wfAbruptExit()
 444                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 445                         }
 446                 }
 447                 $this->ignoreErrors( $ignore );
 448         }
 449
 450
 451         /**
 452          * Intended to be compatible with the PEAR::DB wrapper functions.
 453          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 454          *
 455          * ? = scalar value, quoted as necessary
 456          * ! = raw SQL bit (a function for instance)
 457          * & = filename; reads the file and inserts as a blob
 458          *     (we don't use this though...)
 459          */
 460         function prepare( $sql, $func = 'Database::prepare' ) {
 461                 /* MySQL doesn't support prepared statements (yet), so just
 462                    pack up the query for reference. We'll manually replace
 463                    the bits later. */
 464                 return array( 'query' => $sql, 'func' => $func );
 465         }
 466
 467         function freePrepared( $prepared ) {
 468                 /* No-op for MySQL */
 469         }
 470
 471         /**
 472          * Execute a prepared query with the various arguments
 473          * @param string $prepared the prepared sql
 474          * @param mixed $args Either an array here, or put scalars as varargs
 475          */
 476         function execute( $prepared, $args = null ) {
 477                 if( !is_array( $args ) ) {
 478                         # Pull the var args
 479                         $args = func_get_args();
 480                         array_shift( $args );
 481                 }
 482                 $sql = $this->fillPrepared( $prepared['query'], $args );
 483                 return $this->query( $sql, $prepared['func'] );
 484         }
 485
 486         /**
 487          * Prepare & execute an SQL statement, quoting and inserting arguments
 488          * in the appropriate places.
 489          * @param string $query
 490          * @param string $args ...
 491          */
 492         function safeQuery( $query, $args = null ) {
 493                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 494                 if( !is_array( $args ) ) {
 495                         # Pull the var args
 496                         $args = func_get_args();
 497                         array_shift( $args );
 498                 }
 499                 $retval = $this->execute( $prepared, $args );
 500                 $this->freePrepared( $prepared );
 501                 return $retval;
 502         }
 503
 504         /**
 505          * For faking prepared SQL statements on DBs that don't support
 506          * it directly.
 507          * @param string $preparedSql - a 'preparable' SQL statement
 508          * @param array $args - array of arguments to fill it with
 509          * @return string executable SQL
 510          */
 511         function fillPrepared( $preparedQuery, $args ) {
 512                 $n = 0;
 513                 reset( $args );
 514                 $this->preparedArgs =& $args;
 515                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 516                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 517         }
 518
 519         /**
 520          * preg_callback func for fillPrepared()
 521          * The arguments should be in $this->preparedArgs and must not be touched
 522          * while we're doing this.
 523          *
 524          * @param array $matches
 525          * @return string
 526          * @access private
 527          */
 528         function fillPreparedArg( $matches ) {
 529                 switch( $matches[1] ) {
 530                         case '\\?': return '?';
 531                         case '\\!': return '!';
 532                         case '\\&': return '&';
 533                 }
 534                 list( $n, $arg ) = each( $this->preparedArgs );
 535                 switch( $matches[1] ) {
 536                         case '?': return $this->addQuotes( $arg );
 537                         case '!': return $arg;
 538                         case '&':
 539                                 # return $this->addQuotes( file_get_contents( $arg ) );
 540                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 541                         default:
 542                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 543                 }
 544         }
 545
 546         /**#@+
 547          * @param mixed $res A SQL result
 548          */
 549         /**
 550          * Free a result object
 551          */
 552         function freeResult( $res ) {
 553                 if ( !@/**/mysql_free_result( $res ) ) {
 554                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 555                 }
 556         }
 557
 558         /**
 559          * Fetch the next row from the given result object, in object form
 560          */
 561         function fetchObject( $res ) {
 562                 @/**/$row = mysql_fetch_object( $res );
 563                 if( mysql_errno() ) {
 564                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 565                 }
 566                 return $row;
 567         }
 568
 569         /**
 570          * Fetch the next row from the given result object
 571          * Returns an array
 572          */
 573         function fetchRow( $res ) {
 574                 @/**/$row = mysql_fetch_array( $res );
 575                 if (mysql_errno() ) {
 576                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 577                 }
 578                 return $row;
 579         }
 580
 581         /**
 582          * Get the number of rows in a result object
 583          */
 584         function numRows( $res ) {
 585                 @/**/$n = mysql_num_rows( $res );
 586                 if( mysql_errno() ) {
 587                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 588                 }
 589                 return $n;
 590         }
 591
 592         /**
 593          * Get the number of fields in a result object
 594          * See documentation for mysql_num_fields()
 595          */
 596         function numFields( $res ) { return mysql_num_fields( $res ); }
 597
 598         /**
 599          * Get a field name in a result object
 600          * See documentation for mysql_field_name()
 601          */
 602         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 603
 604         /**
 605          * Get the inserted value of an auto-increment row
 606          *
 607          * The value inserted should be fetched from nextSequenceValue()
 608          *
 609          * Example:
 610          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 611          * $dbw->insert('page',array('page_id' => $id));
 612          * $id = $dbw->insertId();
 613          */
 614         function insertId() { return mysql_insert_id( $this->mConn ); }
 615
 616         /**
 617          * Change the position of the cursor in a result object
 618          * See mysql_data_seek()
 619          */
 620         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 621
 622         /**
 623          * Get the last error number
 624          * See mysql_errno()
 625          */
 626         function lastErrno() {
 627                 if ( $this->mConn ) {
 628                         return mysql_errno( $this->mConn );
 629                 } else {
 630                         return mysql_errno();
 631                 }
 632         }
 633
 634         /**
 635          * Get a description of the last error
 636          * See mysql_error() for more details
 637          */
 638         function lastError() {
 639                 if ( $this->mConn ) {
 640                         # Even if it's non-zero, it can still be invalid
 641                         wfSuppressWarnings();
 642                         $error = mysql_error( $this->mConn );
 643                         if ( !$error ) {
 644                                 $error = mysql_error();
 645                         }
 646                         wfRestoreWarnings();
 647                 } else {
 648                         $error = mysql_error();
 649                 }
 650                 if( $error ) {
 651                         $error .= ' (' . $this->mServer . ')';
 652                 }
 653                 return $error;
 654         }
 655         /**
 656          * Get the number of rows affected by the last write query
 657          * See mysql_affected_rows() for more details
 658          */
 659         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 660         /**#@-*/ // end of template : @param $result
 661
 662         /**
 663          * Simple UPDATE wrapper
 664          * Usually aborts on failure
 665          * If errors are explicitly ignored, returns success
 666          *
 667          * This function exists for historical reasons, Database::update() has a more standard
 668          * calling convention and feature set
 669          */
 670         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 671         {
 672                 $table = $this->tableName( $table );
 673                 $sql = "UPDATE $table SET $var = '" .
 674                   $this->strencode( $value ) . "' WHERE ($cond)";
 675                 return (bool)$this->query( $sql, DB_MASTER, $fname );
 676         }
 677
 678         /**
 679          * Simple SELECT wrapper, returns a single field, input must be encoded
 680          * Usually aborts on failure
 681          * If errors are explicitly ignored, returns FALSE on failure
 682          */
 683         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 684                 if ( !is_array( $options ) ) {
 685                         $options = array( $options );
 686                 }
 687                 $options['LIMIT'] = 1;
 688
 689                 $res = $this->select( $table, $var, $cond, $fname, $options );
 690                 if ( $res === false || !$this->numRows( $res ) ) {
 691                         return false;
 692                 }
 693                 $row = $this->fetchRow( $res );
 694                 if ( $row !== false ) {
 695                         $this->freeResult( $res );
 696                         return $row[0];
 697                 } else {
 698                         return false;
 699                 }
 700         }
 701
 702         /**
 703          * Returns an optional USE INDEX clause to go after the table, and a
 704          * string to go at the end of the query
 705          *
 706          * @access private
 707          *
 708          * @param array $options an associative array of options to be turned into
 709          *              an SQL query, valid keys are listed in the function.
 710          * @return array
 711          */
 712         function makeSelectOptions( $options ) {
 713                 $tailOpts = '';
 714
 715                 if ( isset( $options['GROUP BY'] ) ) {
 716                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 717                 }
 718                 if ( isset( $options['ORDER BY'] ) ) {
 719                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 720                 }
 721                 if (isset($options['LIMIT'])) {
 722                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 723                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 724                 }
 725                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 726                         $tailOpts .= ' FOR UPDATE';
 727                 }
 728
 729                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 730                         $tailOpts .= ' LOCK IN SHARE MODE';
 731                 }
 732
 733                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 734                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 735                 } else {
 736                         $useIndex = '';
 737                 }
 738                 return array( $useIndex, $tailOpts );
 739         }
 740
 741         /**
 742          * SELECT wrapper
 743          */
 744         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 745         {
 746                 if( is_array( $vars ) ) {
 747                         $vars = implode( ',', $vars );
 748                 }
 749                 if( !is_array( $options ) ) {
 750                         $options = array( $options );
 751                 }
 752                 if( is_array( $table ) ) {
 753                         if ( @is_array( $options['USE INDEX'] ) )
 754                                 $from = ' FROM ' . $this->tableNamesWithUseIndex( $table, $options['USE INDEX'] );
 755                         else
 756                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 757                 } elseif ($table!='') {
 758                         $from = ' FROM ' . $this->tableName( $table );
 759                 } else {
 760                         $from = '';
 761                 }
 762
 763                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 764
 765                 if( !empty( $conds ) ) {
 766                         if ( is_array( $conds ) ) {
 767                                 $conds = $this->makeList( $conds, LIST_AND );
 768                         }
 769                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 770                 } else {
 771                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 772                 }
 773
 774                 return $this->query( $sql, $fname );
 775         }
 776
 777         /**
 778          * Single row SELECT wrapper
 779          * Aborts or returns FALSE on error
 780          *
 781          * $vars: the selected variables
 782          * $conds: a condition map, terms are ANDed together.
 783          *   Items with numeric keys are taken to be literal conditions
 784          * Takes an array of selected variables, and a condition map, which is ANDed
 785          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 786          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 787          * $obj- >page_id is the ID of the Astronomy article
 788          *
 789          * @todo migrate documentation to phpdocumentor format
 790          */
 791         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 792                 $options['LIMIT'] = 1;
 793                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 794                 if ( $res === false )
 795                         return false;
 796                 if ( !$this->numRows($res) ) {
 797                         $this->freeResult($res);
 798                         return false;
 799                 }
 800                 $obj = $this->fetchObject( $res );
 801                 $this->freeResult( $res );
 802                 return $obj;
 803
 804         }
 805
 806         /**
 807          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 808          * It's only slightly flawed. Don't use for anything important.
 809          *
 810          * @param string $sql A SQL Query
 811          * @static
 812          */
 813         function generalizeSQL( $sql ) {
 814                 # This does the same as the regexp below would do, but in such a way
 815                 # as to avoid crashing php on some large strings.
 816                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 817
 818                 $sql = str_replace ( "\\\\", '', $sql);
 819                 $sql = str_replace ( "\\'", '', $sql);
 820                 $sql = str_replace ( "\\\"", '', $sql);
 821                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 822                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 823
 824                 # All newlines, tabs, etc replaced by single space
 825                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 826
 827                 # All numbers => N
 828                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 829
 830                 return $sql;
 831         }
 832
 833         /**
 834          * Determines whether a field exists in a table
 835          * Usually aborts on failure
 836          * If errors are explicitly ignored, returns NULL on failure
 837          */
 838         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 839                 $table = $this->tableName( $table );
 840                 $res = $this->query( 'DESCRIBE '.$table, DB_SLAVE, $fname );
 841                 if ( !$res ) {
 842                         return NULL;
 843                 }
 844
 845                 $found = false;
 846
 847                 while ( $row = $this->fetchObject( $res ) ) {
 848                         if ( $row->Field == $field ) {
 849                                 $found = true;
 850                                 break;
 851                         }
 852                 }
 853                 return $found;
 854         }
 855
 856         /**
 857          * Determines whether an index exists
 858          * Usually aborts on failure
 859          * If errors are explicitly ignored, returns NULL on failure
 860          */
 861         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 862                 $info = $this->indexInfo( $table, $index, $fname );
 863                 if ( is_null( $info ) ) {
 864                         return NULL;
 865                 } else {
 866                         return $info !== false;
 867                 }
 868         }
 869
 870
 871         /**
 872          * Get information about an index into an object
 873          * Returns false if the index does not exist
 874          */
 875         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 876                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 877                 # SHOW INDEX should work for 3.x and up:
 878                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 879                 $table = $this->tableName( $table );
 880                 $sql = 'SHOW INDEX FROM '.$table;
 881                 $res = $this->query( $sql, $fname );
 882                 if ( !$res ) {
 883                         return NULL;
 884                 }
 885
 886                 while ( $row = $this->fetchObject( $res ) ) {
 887                         if ( $row->Key_name == $index ) {
 888                                 return $row;
 889                         }
 890                 }
 891                 return false;
 892         }
 893
 894         /**
 895          * Query whether a given table exists
 896          */
 897         function tableExists( $table ) {
 898                 $table = $this->tableName( $table );
 899                 $old = $this->ignoreErrors( true );
 900                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 901                 $this->ignoreErrors( $old );
 902                 if( $res ) {
 903                         $this->freeResult( $res );
 904                         return true;
 905                 } else {
 906                         return false;
 907                 }
 908         }
 909
 910         /**
 911          * mysql_fetch_field() wrapper
 912          * Returns false if the field doesn't exist
 913          *
 914          * @param $table
 915          * @param $field
 916          */
 917         function fieldInfo( $table, $field ) {
 918                 $table = $this->tableName( $table );
 919                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 920                 $n = mysql_num_fields( $res );
 921                 for( $i = 0; $i < $n; $i++ ) {
 922                         $meta = mysql_fetch_field( $res, $i );
 923                         if( $field == $meta->name ) {
 924                                 return $meta;
 925                         }
 926                 }
 927                 return false;
 928         }
 929
 930         /**
 931          * mysql_field_type() wrapper
 932          */
 933         function fieldType( $res, $index ) {
 934                 return mysql_field_type( $res, $index );
 935         }
 936
 937         /**
 938          * Determines if a given index is unique
 939          */
 940         function indexUnique( $table, $index ) {
 941                 $indexInfo = $this->indexInfo( $table, $index );
 942                 if ( !$indexInfo ) {
 943                         return NULL;
 944                 }
 945                 return !$indexInfo->Non_unique;
 946         }
 947
 948         /**
 949          * INSERT wrapper, inserts an array into a table
 950          *
 951          * $a may be a single associative array, or an array of these with numeric keys, for
 952          * multi-row insert.
 953          *
 954          * Usually aborts on failure
 955          * If errors are explicitly ignored, returns success
 956          */
 957         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 958                 # No rows to insert, easy just return now
 959                 if ( !count( $a ) ) {
 960                         return true;
 961                 }
 962
 963                 $table = $this->tableName( $table );
 964                 if ( !is_array( $options ) ) {
 965                         $options = array( $options );
 966                 }
 967                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
 968                         $multi = true;
 969                         $keys = array_keys( $a[0] );
 970                 } else {
 971                         $multi = false;
 972                         $keys = array_keys( $a );
 973                 }
 974
 975                 $sql = 'INSERT ' . implode( ' ', $options ) .
 976                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 977
 978                 if ( $multi ) {
 979                         $first = true;
 980                         foreach ( $a as $row ) {
 981                                 if ( $first ) {
 982                                         $first = false;
 983                                 } else {
 984                                         $sql .= ',';
 985                                 }
 986                                 $sql .= '(' . $this->makeList( $row ) . ')';
 987                         }
 988                 } else {
 989                         $sql .= '(' . $this->makeList( $a ) . ')';
 990                 }
 991                 return (bool)$this->query( $sql, $fname );
 992         }
 993
 994         /**
 995          * Make UPDATE options for the Database::update function
 996          *
 997          * @access private
 998          * @param array $options The options passed to Database::update
 999          * @return string
1000          */
1001         function makeUpdateOptions( $options ) {
1002                 if( !is_array( $options ) ) {
1003                         $options = array( $options );
1004                 }
1005                 $opts = array();
1006                 if ( in_array( 'LOW_PRIORITY', $options ) )
1007                         $opts[] = $this->lowPriorityOption();
1008                 if ( in_array( 'IGNORE', $options ) )
1009                         $opts[] = 'IGNORE';
1010                 return implode(' ', $opts);
1011         }
1012
1013         /**
1014          * UPDATE wrapper, takes a condition array and a SET array
1015          *
1016          * @param string $table  The table to UPDATE
1017          * @param array  $values An array of values to SET
1018          * @param array  $conds  An array of conditions (WHERE)
1019          * @param string $fname  The Class::Function calling this function
1020          *                       (for the log)
1021          * @param array  $options An array of UPDATE options, can be one or
1022          *                        more of IGNORE, LOW_PRIORITY
1023          */
1024         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1025                 $table = $this->tableName( $table );
1026                 $opts = $this->makeUpdateOptions( $options );
1027                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1028                 if ( $conds != '*' ) {
1029                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1030                 }
1031                 $this->query( $sql, $fname );
1032         }
1033
1034         /**
1035          * Makes a wfStrencoded list from an array
1036          * $mode: LIST_COMMA         - comma separated, no field names
1037          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1038          *        LIST_SET           - comma separated with field names, like a SET clause
1039          *        LIST_NAMES         - comma separated field names
1040          */
1041         function makeList( $a, $mode = LIST_COMMA ) {
1042                 if ( !is_array( $a ) ) {
1043                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1044                 }
1045
1046                 $first = true;
1047                 $list = '';
1048                 foreach ( $a as $field => $value ) {
1049                         if ( !$first ) {
1050                                 if ( $mode == LIST_AND ) {
1051                                         $list .= ' AND ';
1052                                 } elseif($mode == LIST_OR) {
1053                                         $list .= ' OR ';
1054                                 } else {
1055                                         $list .= ',';
1056                                 }
1057                         } else {
1058                                 $first = false;
1059                         }
1060                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1061                                 $list .= "($value)";
1062                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1063                                 $list .= $field." IN (".$this->makeList($value).") ";
1064                         } else {
1065                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1066                                         $list .= "$field = ";
1067                                 }
1068                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1069                         }
1070                 }
1071                 return $list;
1072         }
1073
1074         /**
1075          * Change the current database
1076          */
1077         function selectDB( $db ) {
1078                 $this->mDBname = $db;
1079                 return mysql_select_db( $db, $this->mConn );
1080         }
1081
1082         /**
1083          * Starts a timer which will kill the DB thread after $timeout seconds
1084          */
1085         function startTimer( $timeout ) {
1086                 global $IP;
1087                 if( function_exists( 'mysql_thread_id' ) ) {
1088                         # This will kill the query if it's still running after $timeout seconds.
1089                         $tid = mysql_thread_id( $this->mConn );
1090                         exec( "php $IP/includes/killthread.php $timeout $tid &>/dev/null &" );
1091                 }
1092         }
1093
1094         /**
1095          * Stop a timer started by startTimer()
1096          * Currently unimplemented.
1097          *
1098          */
1099         function stopTimer() { }
1100
1101         /**
1102          * Format a table name ready for use in constructing an SQL query
1103          *
1104          * This does two important things: it quotes table names which as necessary,
1105          * and it adds a table prefix if there is one.
1106          *
1107          * All functions of this object which require a table name call this function
1108          * themselves. Pass the canonical name to such functions. This is only needed
1109          * when calling query() directly.
1110          *
1111          * @param string $name database table name
1112          */
1113         function tableName( $name ) {
1114                 global $wgSharedDB;
1115                 # Skip quoted literals
1116                 if ( $name{0} != '`' ) {
1117                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1118                                 $name = "{$this->mTablePrefix}$name";
1119                         }
1120                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1121                                 $name = "`$wgSharedDB`.`$name`";
1122                         } else {
1123                                 # Standard quoting
1124                                 $name = "`$name`";
1125                         }
1126                 }
1127                 return $name;
1128         }
1129
1130         /**
1131          * Fetch a number of table names into an array
1132          * This is handy when you need to construct SQL for joins
1133          *
1134          * Example:
1135          * extract($dbr->tableNames('user','watchlist'));
1136          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1137          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1138          */
1139         function tableNames() {
1140                 $inArray = func_get_args();
1141                 $retVal = array();
1142                 foreach ( $inArray as $name ) {
1143                         $retVal[$name] = $this->tableName( $name );
1144                 }
1145                 return $retVal;
1146         }
1147
1148         /**
1149          * @access private
1150          */
1151         function tableNamesWithUseIndex( $tables, $use_index ) {
1152                 $ret = array();
1153
1154                 foreach ( $tables as $table )
1155                         if ( @$use_index[$table] !== null )
1156                                 $ret[] = $this->tableName( $table ) . ' ' . $this->useIndexClause( implode( ',', (array)$use_index[$table] ) );
1157                         else
1158                                 $ret[] = $this->tableName( $table );
1159
1160                 return implode( ',', $ret );
1161         }
1162
1163         /**
1164          * Wrapper for addslashes()
1165          * @param string $s String to be slashed.
1166          * @return string slashed string.
1167          */
1168         function strencode( $s ) {
1169                 return addslashes( $s );
1170         }
1171
1172         /**
1173          * If it's a string, adds quotes and backslashes
1174          * Otherwise returns as-is
1175          */
1176         function addQuotes( $s ) {
1177                 if ( is_null( $s ) ) {
1178                         return 'NULL';
1179                 } else {
1180                         # This will also quote numeric values. This should be harmless,
1181                         # and protects against weird problems that occur when they really
1182                         # _are_ strings such as article titles and string->number->string
1183                         # conversion is not 1:1.
1184                         return "'" . $this->strencode( $s ) . "'";
1185                 }
1186         }
1187
1188         /**
1189          * Escape string for safe LIKE usage
1190          */
1191         function escapeLike( $s ) {
1192                 $s=$this->strencode( $s );
1193                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1194                 return $s;
1195         }
1196
1197         /**
1198          * Returns an appropriately quoted sequence value for inserting a new row.
1199          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1200          * subclass will return an integer, and save the value for insertId()
1201          */
1202         function nextSequenceValue( $seqName ) {
1203                 return NULL;
1204         }
1205
1206         /**
1207          * USE INDEX clause
1208          * PostgreSQL doesn't have them and returns ""
1209          */
1210         function useIndexClause( $index ) {
1211                 return "FORCE INDEX ($index)";
1212         }
1213
1214         /**
1215          * REPLACE query wrapper
1216          * PostgreSQL simulates this with a DELETE followed by INSERT
1217          * $row is the row to insert, an associative array
1218          * $uniqueIndexes is an array of indexes. Each element may be either a
1219          * field name or an array of field names
1220          *
1221          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1222          * However if you do this, you run the risk of encountering errors which wouldn't have
1223          * occurred in MySQL
1224          *
1225          * @todo migrate comment to phodocumentor format
1226          */
1227         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1228                 $table = $this->tableName( $table );
1229
1230                 # Single row case
1231                 if ( !is_array( reset( $rows ) ) ) {
1232                         $rows = array( $rows );
1233                 }
1234
1235                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1236                 $first = true;
1237                 foreach ( $rows as $row ) {
1238                         if ( $first ) {
1239                                 $first = false;
1240                         } else {
1241                                 $sql .= ',';
1242                         }
1243                         $sql .= '(' . $this->makeList( $row ) . ')';
1244                 }
1245                 return $this->query( $sql, $fname );
1246         }
1247
1248         /**
1249          * DELETE where the condition is a join
1250          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1251          *
1252          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1253          * join condition matches, set $conds='*'
1254          *
1255          * DO NOT put the join condition in $conds
1256          *
1257          * @param string $delTable The table to delete from.
1258          * @param string $joinTable The other table.
1259          * @param string $delVar The variable to join on, in the first table.
1260          * @param string $joinVar The variable to join on, in the second table.
1261          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1262          */
1263         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1264                 if ( !$conds ) {
1265                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1266                 }
1267
1268                 $delTable = $this->tableName( $delTable );
1269                 $joinTable = $this->tableName( $joinTable );
1270                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1271                 if ( $conds != '*' ) {
1272                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1273                 }
1274
1275                 return $this->query( $sql, $fname );
1276         }
1277
1278         /**
1279          * Returns the size of a text field, or -1 for "unlimited"
1280          */
1281         function textFieldSize( $table, $field ) {
1282                 $table = $this->tableName( $table );
1283                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1284                 $res = $this->query( $sql, 'Database::textFieldSize' );
1285                 $row = $this->fetchObject( $res );
1286                 $this->freeResult( $res );
1287
1288                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1289                         $size = $m[1];
1290                 } else {
1291                         $size = -1;
1292                 }
1293                 return $size;
1294         }
1295
1296         /**
1297          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1298          */
1299         function lowPriorityOption() {
1300                 return 'LOW_PRIORITY';
1301         }
1302
1303         /**
1304          * DELETE query wrapper
1305          *
1306          * Use $conds == "*" to delete all rows
1307          */
1308         function delete( $table, $conds, $fname = 'Database::delete' ) {
1309                 if ( !$conds ) {
1310                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1311                 }
1312                 $table = $this->tableName( $table );
1313                 $sql = "DELETE FROM $table";
1314                 if ( $conds != '*' ) {
1315                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1316                 }
1317                 return $this->query( $sql, $fname );
1318         }
1319
1320         /**
1321          * INSERT SELECT wrapper
1322          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1323          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1324          * $conds may be "*" to copy the whole table
1325          * srcTable may be an array of tables.
1326          */
1327         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect' ) {
1328                 $destTable = $this->tableName( $destTable );
1329                 if( is_array( $srcTable ) ) {
1330                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1331                 } else {
1332                         $srcTable = $this->tableName( $srcTable );
1333                 }
1334                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1335                         ' SELECT ' . implode( ',', $varMap ) .
1336                         " FROM $srcTable";
1337                 if ( $conds != '*' ) {
1338                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1339                 }
1340                 return $this->query( $sql, $fname );
1341         }
1342
1343         /**
1344          * Construct a LIMIT query with optional offset
1345          * This is used for query pages
1346          * $sql string SQL query we will append the limit too
1347          * $limit integer the SQL limit
1348          * $offset integer the SQL offset (default false)
1349          */
1350         function limitResult($sql, $limit, $offset=false) {
1351                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1352         }
1353         function limitResultForUpdate($sql, $num) {
1354                 return $this->limitResult($sql, $num, 0);
1355         }
1356
1357         /**
1358          * Returns an SQL expression for a simple conditional.
1359          * Uses IF on MySQL.
1360          *
1361          * @param string $cond SQL expression which will result in a boolean value
1362          * @param string $trueVal SQL expression to return if true
1363          * @param string $falseVal SQL expression to return if false
1364          * @return string SQL fragment
1365          */
1366         function conditional( $cond, $trueVal, $falseVal ) {
1367                 return " IF($cond, $trueVal, $falseVal) ";
1368         }
1369
1370         /**
1371          * Determines if the last failure was due to a deadlock
1372          */
1373         function wasDeadlock() {
1374                 return $this->lastErrno() == 1213;
1375         }
1376
1377         /**
1378          * Perform a deadlock-prone transaction.
1379          *
1380          * This function invokes a callback function to perform a set of write
1381          * queries. If a deadlock occurs during the processing, the transaction
1382          * will be rolled back and the callback function will be called again.
1383          *
1384          * Usage:
1385          *   $dbw->deadlockLoop( callback, ... );
1386          *
1387          * Extra arguments are passed through to the specified callback function.
1388          *
1389          * Returns whatever the callback function returned on its successful,
1390          * iteration, or false on error, for example if the retry limit was
1391          * reached.
1392          */
1393         function deadlockLoop() {
1394                 $myFname = 'Database::deadlockLoop';
1395
1396                 $this->begin();
1397                 $args = func_get_args();
1398                 $function = array_shift( $args );
1399                 $oldIgnore = $this->ignoreErrors( true );
1400                 $tries = DEADLOCK_TRIES;
1401                 if ( is_array( $function ) ) {
1402                         $fname = $function[0];
1403                 } else {
1404                         $fname = $function;
1405                 }
1406                 do {
1407                         $retVal = call_user_func_array( $function, $args );
1408                         $error = $this->lastError();
1409                         $errno = $this->lastErrno();
1410                         $sql = $this->lastQuery();
1411
1412                         if ( $errno ) {
1413                                 if ( $this->wasDeadlock() ) {
1414                                         # Retry
1415                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1416                                 } else {
1417                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1418                                 }
1419                         }
1420                 } while( $this->wasDeadlock() && --$tries > 0 );
1421                 $this->ignoreErrors( $oldIgnore );
1422                 if ( $tries <= 0 ) {
1423                         $this->query( 'ROLLBACK', $myFname );
1424                         $this->reportQueryError( $error, $errno, $sql, $fname );
1425                         return false;
1426                 } else {
1427                         $this->query( 'COMMIT', $myFname );
1428                         return $retVal;
1429                 }
1430         }
1431
1432         /**
1433          * Do a SELECT MASTER_POS_WAIT()
1434          *
1435          * @param string $file the binlog file
1436          * @param string $pos the binlog position
1437          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1438          */
1439         function masterPosWait( $file, $pos, $timeout ) {
1440                 $fname = 'Database::masterPosWait';
1441                 wfProfileIn( $fname );
1442
1443
1444                 # Commit any open transactions
1445                 $this->immediateCommit();
1446
1447                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1448                 $encFile = $this->strencode( $file );
1449                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1450                 $res = $this->doQuery( $sql );
1451                 if ( $res && $row = $this->fetchRow( $res ) ) {
1452                         $this->freeResult( $res );
1453                         wfProfileOut( $fname );
1454                         return $row[0];
1455                 } else {
1456                         wfProfileOut( $fname );
1457                         return false;
1458                 }
1459         }
1460
1461         /**
1462          * Get the position of the master from SHOW SLAVE STATUS
1463          */
1464         function getSlavePos() {
1465                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1466                 $row = $this->fetchObject( $res );
1467                 if ( $row ) {
1468                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1469                 } else {
1470                         return array( false, false );
1471                 }
1472         }
1473
1474         /**
1475          * Get the position of the master from SHOW MASTER STATUS
1476          */
1477         function getMasterPos() {
1478                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1479                 $row = $this->fetchObject( $res );
1480                 if ( $row ) {
1481                         return array( $row->File, $row->Position );
1482                 } else {
1483                         return array( false, false );
1484                 }
1485         }
1486
1487         /**
1488          * Begin a transaction, or if a transaction has already started, continue it
1489          */
1490         function begin( $fname = 'Database::begin' ) {
1491                 if ( !$this->mTrxLevel ) {
1492                         $this->immediateBegin( $fname );
1493                 } else {
1494                         $this->mTrxLevel++;
1495                 }
1496         }
1497
1498         /**
1499          * End a transaction, or decrement the nest level if transactions are nested
1500          */
1501         function commit( $fname = 'Database::commit' ) {
1502                 if ( $this->mTrxLevel ) {
1503                         $this->mTrxLevel--;
1504                 }
1505                 if ( !$this->mTrxLevel ) {
1506                         $this->immediateCommit( $fname );
1507                 }
1508         }
1509
1510         /**
1511          * Rollback a transaction
1512          */
1513         function rollback( $fname = 'Database::rollback' ) {
1514                 $this->query( 'ROLLBACK', $fname );
1515                 $this->mTrxLevel = 0;
1516         }
1517
1518         /**
1519          * Begin a transaction, committing any previously open transaction
1520          */
1521         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1522                 $this->query( 'BEGIN', $fname );
1523                 $this->mTrxLevel = 1;
1524         }
1525
1526         /**
1527          * Commit transaction, if one is open
1528          */
1529         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1530                 $this->query( 'COMMIT', $fname );
1531                 $this->mTrxLevel = 0;
1532         }
1533
1534         /**
1535          * Return MW-style timestamp used for MySQL schema
1536          */
1537         function timestamp( $ts=0 ) {
1538                 return wfTimestamp(TS_MW,$ts);
1539         }
1540
1541         /**
1542          * Local database timestamp format or null
1543          */
1544         function timestampOrNull( $ts = null ) {
1545                 if( is_null( $ts ) ) {
1546                         return null;
1547                 } else {
1548                         return $this->timestamp( $ts );
1549                 }
1550         }
1551
1552         /**
1553          * @todo document
1554          */
1555         function resultObject( $result ) {
1556                 if( empty( $result ) ) {
1557                         return NULL;
1558                 } else {
1559                         return new ResultWrapper( $this, $result );
1560                 }
1561         }
1562
1563         /**
1564          * Return aggregated value alias
1565          */
1566         function aggregateValue ($valuedata,$valuename='value') {
1567                 return $valuename;
1568         }
1569
1570         /**
1571          * @return string wikitext of a link to the server software's web site
1572          */
1573         function getSoftwareLink() {
1574                 return "[http://www.mysql.com/ MySQL]";
1575         }
1576
1577         /**
1578          * @return string Version information from the database
1579          */
1580         function getServerVersion() {
1581                 return mysql_get_server_info();
1582         }
1583
1584         /**
1585          * Ping the server and try to reconnect if it there is no connection
1586          */
1587         function ping() {
1588                 if( function_exists( 'mysql_ping' ) ) {
1589                         return mysql_ping( $this->mConn );
1590                 } else {
1591                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1592                         return true;
1593                 }
1594         }
1595
1596         /**
1597          * Get slave lag.
1598          * At the moment, this will only work if the DB user has the PROCESS privilege
1599          */
1600         function getLag() {
1601                 $res = $this->query( 'SHOW PROCESSLIST' );
1602                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1603                 # dubious, but unfortunately there's no easy rigorous way
1604                 $slaveThreads = 0;
1605                 while ( $row = $this->fetchObject( $res ) ) {
1606                         if ( $row->User == 'system user' ) {
1607                                 if ( ++$slaveThreads == 2 ) {
1608                                         # This is it, return the time
1609                                         return $row->Time;
1610                                 }
1611                         }
1612                 }
1613                 return false;
1614         }
1615
1616         /**
1617          * Get status information from SHOW STATUS in an associative array
1618          */
1619         function getStatus() {
1620                 $res = $this->query( 'SHOW STATUS' );
1621                 $status = array();
1622                 while ( $row = $this->fetchObject( $res ) ) {
1623                         $status[$row->Variable_name] = $row->Value;
1624                 }
1625                 return $status;
1626         }
1627
1628         /**
1629          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1630          */
1631         function maxListLen() {
1632                 return 0;
1633         }
1634
1635         function encodeBlob($b) {
1636                 return $b;
1637         }
1638
1639         function notNullTimestamp() {
1640                 return "!= 0";
1641         }
1642         function isNullTimestamp() {
1643                 return "= '0'";
1644         }
1645 }
1646
1647 /**
1648  * Database abstraction object for mySQL
1649  * Inherit all methods and properties of Database::Database()
1650  *
1651  * @package MediaWiki
1652  * @see Database
1653  */
1654 class DatabaseMysql extends Database {
1655         # Inherit all
1656 }
1657
1658
1659 /**
1660  * Result wrapper for grabbing data queried by someone else
1661  *
1662  * @package MediaWiki
1663  */
1664 class ResultWrapper {
1665         var $db, $result;
1666
1667         /**
1668          * @todo document
1669          */
1670         function ResultWrapper( $database, $result ) {
1671                 $this->db =& $database;
1672                 $this->result =& $result;
1673         }
1674
1675         /**
1676          * @todo document
1677          */
1678         function numRows() {
1679                 return $this->db->numRows( $this->result );
1680         }
1681
1682         /**
1683          * @todo document
1684          */
1685         function fetchObject() {
1686                 return $this->db->fetchObject( $this->result );
1687         }
1688
1689         /**
1690          * @todo document
1691          */
1692         function &fetchRow() {
1693                 return $this->db->fetchRow( $this->result );
1694         }
1695
1696         /**
1697          * @todo document
1698          */
1699         function free() {
1700                 $this->db->freeResult( $this->result );
1701                 unset( $this->result );
1702                 unset( $this->db );
1703         }
1704
1705         function seek( $row ) {
1706                 $this->db->dataSeek( $this->result, $row );
1707         }
1708 }
1709
1710 #------------------------------------------------------------------------------
1711 # Global functions
1712 #------------------------------------------------------------------------------
1713
1714 /**
1715  * Standard fail function, called by default when a connection cannot be
1716  * established.
1717  * Displays the file cache if possible
1718  */
1719 function wfEmergencyAbort( &$conn, $error ) {
1720         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1721         global $wgSitename, $wgServer, $wgMessageCache, $wgLogo;
1722
1723         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1724         # Hard coding strings instead.
1725
1726         $noconnect = "<h1><img src='$wgLogo' style='float:left;margin-right:1em' alt=''>$wgSitename has a problem</h1><p><strong>Sorry! This site is experiencing technical difficulties.</strong></p><p>Try waiting a few minutes and reloading.</p><p><small>(Can't contact the database server: $1)</small></p>";
1727         $mainpage = 'Main Page';
1728         $searchdisabled = <<<EOT
1729 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1730 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1731 EOT;
1732
1733         $googlesearch = "
1734 <!-- SiteSearch Google -->
1735 <FORM method=GET action=\"http://www.google.com/search\">
1736 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1737 <A HREF=\"http://www.google.com/\">
1738 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1739 border=\"0\" ALT=\"Google\"></A>
1740 </td>
1741 <td>
1742 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1743 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1744 <font size=-1>
1745 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1746 <input type='hidden' name='ie' value='$2'>
1747 <input type='hidden' name='oe' value='$2'>
1748 </font>
1749 </td></tr></TABLE>
1750 </FORM>
1751 <!-- SiteSearch Google -->";
1752         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1753
1754
1755         if( !headers_sent() ) {
1756                 header( 'HTTP/1.0 500 Internal Server Error' );
1757                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1758                 /* Don't cache error pages!  They cause no end of trouble... */
1759                 header( 'Cache-control: none' );
1760                 header( 'Pragma: nocache' );
1761         }
1762
1763         # No database access
1764         if ( is_object( $wgMessageCache ) ) {
1765                 $wgMessageCache->disable();
1766         }
1767
1768         $msg = wfGetSiteNotice();
1769         if($msg == '') {
1770                 $msg = str_replace( '$1', $error, $noconnect );
1771         }
1772         $text = $msg;
1773
1774         if($wgUseFileCache) {
1775                 if($wgTitle) {
1776                         $t =& $wgTitle;
1777                 } else {
1778                         if($title) {
1779                                 $t = Title::newFromURL( $title );
1780                         } elseif (@/**/$_REQUEST['search']) {
1781                                 $search = $_REQUEST['search'];
1782                                 echo $searchdisabled;
1783                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1784                                   $wgInputEncoding ), $googlesearch );
1785                                 wfErrorExit();
1786                         } else {
1787                                 $t = Title::newFromText( $mainpage );
1788                         }
1789                 }
1790
1791                 $cache = new CacheManager( $t );
1792                 if( $cache->isFileCached() ) {
1793                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1794                                 $cachederror . "</b></p>\n";
1795
1796                         $tag = '<div id="article">';
1797                         $text = str_replace(
1798                                 $tag,
1799                                 $tag . $msg,
1800                                 $cache->fetchPageText() );
1801                 }
1802         }
1803
1804         echo $text;
1805         wfErrorExit();
1806 }
1807
1808 ?>