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