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