includes/Database.php

   1 <?php
   2 /**
   3  * This file deals with MySQL interface functions
   4  * and query specifics/optimisations
   5  * @package MediaWiki
   6  */
   7
   8 /**
   9  * Depends on the CacheManager
  10  */
  11 require_once( 'CacheManager.php' );
  12
  13 /** See Database::makeList() */
  14 define( 'LIST_COMMA', 0 );
  15 define( 'LIST_AND', 1 );
  16 define( 'LIST_SET', 2 );
  17 define( 'LIST_NAMES', 3);
  18 define( 'LIST_OR', 4);
  19
  20 /** Number of times to re-try an operation in case of deadlock */
  21 define( 'DEADLOCK_TRIES', 4 );
  22 /** Minimum time to wait before retry, in microseconds */
  23 define( 'DEADLOCK_DELAY_MIN', 500000 );
  24 /** Maximum time to wait before retry */
  25 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  26
  27 class DBObject {
  28         var $mData;
  29
  30         function DBObject($data) {
  31                 $this->mData = $data;
  32         }
  33
  34         function isLOB() {
  35                 return false;
  36         }
  37
  38         function data() {
  39                 return $this->mData;
  40         }
  41 };
  42
  43 /**
  44  * Database abstraction object
  45  * @package MediaWiki
  46  */
  47 class Database {
  48
  49 #------------------------------------------------------------------------------
  50 # Variables
  51 #------------------------------------------------------------------------------
  52         /**#@+
  53          * @access private
  54          */
  55         var $mLastQuery = '';
  56
  57         var $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
  58         var $mOut, $mOpened = false;
  59
  60         var $mFailFunction;
  61         var $mTablePrefix;
  62         var $mFlags;
  63         var $mTrxLevel = 0;
  64         var $mErrorCount = 0;
  65         /**#@-*/
  66
  67 #------------------------------------------------------------------------------
  68 # Accessors
  69 #------------------------------------------------------------------------------
  70         # These optionally set a variable and return the previous state
  71
  72         /**
  73          * Fail function, takes a Database as a parameter
  74          * Set to false for default, 1 for ignore errors
  75          */
  76         function failFunction( $function = NULL ) {
  77                 return wfSetVar( $this->mFailFunction, $function );
  78         }
  79
  80         /**
  81          * Output page, used for reporting errors
  82          * FALSE means discard output
  83          */
  84         function &setOutputPage( &$out ) {
  85                 $this->mOut =& $out;
  86         }
  87
  88         /**
  89          * Boolean, controls output of large amounts of debug information
  90          */
  91         function debug( $debug = NULL ) {
  92                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
  93         }
  94
  95         /**
  96          * Turns buffering of SQL result sets on (true) or off (false).
  97          * Default is "on" and it should not be changed without good reasons.
  98          */
  99         function bufferResults( $buffer = NULL ) {
 100                 if ( is_null( $buffer ) ) {
 101                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 102                 } else {
 103                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 104                 }
 105         }
 106
 107         /**
 108          * Turns on (false) or off (true) the automatic generation and sending
 109          * of a "we're sorry, but there has been a database error" page on
 110          * database errors. Default is on (false). When turned off, the
 111          * code should use wfLastErrno() and wfLastError() to handle the
 112          * situation as appropriate.
 113          */
 114         function ignoreErrors( $ignoreErrors = NULL ) {
 115                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 116         }
 117
 118         /**
 119          * The current depth of nested transactions
 120          * @param integer $level
 121          */
 122         function trxLevel( $level = NULL ) {
 123                 return wfSetVar( $this->mTrxLevel, $level );
 124         }
 125
 126         /**
 127          * Number of errors logged, only useful when errors are ignored
 128          */
 129         function errorCount( $count = NULL ) {
 130                 return wfSetVar( $this->mErrorCount, $count );
 131         }
 132
 133         /**#@+
 134          * Get function
 135          */
 136         function lastQuery() { return $this->mLastQuery; }
 137         function isOpen() { return $this->mOpened; }
 138         /**#@-*/
 139
 140         function setFlag( $flag ) {
 141                 $this->mFlags |= $flag;
 142         }
 143
 144         function clearFlag( $flag ) {
 145                 $this->mFlags &= ~$flag;
 146         }
 147
 148         function getFlag( $flag ) {
 149                 return !!($this->mFlags & $flag);
 150         }
 151
 152 #------------------------------------------------------------------------------
 153 # Other functions
 154 #------------------------------------------------------------------------------
 155
 156         /**#@+
 157          * @param string $server database server host
 158          * @param string $user database user name
 159          * @param string $password database user password
 160          * @param string $dbname database name
 161          */
 162
 163         /**
 164          * @param failFunction
 165          * @param $flags
 166          * @param string $tablePrefix Database table prefixes. By default use the prefix gave in LocalSettings.php
 167          */
 168         function Database( $server = false, $user = false, $password = false, $dbName = false,
 169                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global' ) {
 170
 171                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 172                 # Can't get a reference if it hasn't been set yet
 173                 if ( !isset( $wgOut ) ) {
 174                         $wgOut = NULL;
 175                 }
 176                 $this->mOut =& $wgOut;
 177
 178                 $this->mFailFunction = $failFunction;
 179                 $this->mFlags = $flags;
 180
 181                 if ( $this->mFlags & DBO_DEFAULT ) {
 182                         if ( $wgCommandLineMode ) {
 183                                 $this->mFlags &= ~DBO_TRX;
 184                         } else {
 185                                 $this->mFlags |= DBO_TRX;
 186                         }
 187                 }
 188
 189                 /*
 190                 // Faster read-only access
 191                 if ( wfReadOnly() ) {
 192                         $this->mFlags |= DBO_PERSISTENT;
 193                         $this->mFlags &= ~DBO_TRX;
 194                 }*/
 195
 196                 /** Get the default table prefix*/
 197                 if ( $tablePrefix == 'get from global' ) {
 198                         $this->mTablePrefix = $wgDBprefix;
 199                 } else {
 200                         $this->mTablePrefix = $tablePrefix;
 201                 }
 202
 203                 if ( $server ) {
 204                         $this->open( $server, $user, $password, $dbName );
 205                 }
 206         }
 207
 208         /**
 209          * @static
 210          * @param failFunction
 211          * @param $flags
 212          */
 213         function newFromParams( $server, $user, $password, $dbName,
 214                 $failFunction = false, $flags = 0 )
 215         {
 216                 return new Database( $server, $user, $password, $dbName, $failFunction, $flags );
 217         }
 218
 219         /**
 220          * Usually aborts on failure
 221          * If the failFunction is set to a non-zero integer, returns success
 222          */
 223         function open( $server, $user, $password, $dbName ) {
 224                 # Test for missing mysql.so
 225                 # First try to load it
 226                 if (!@extension_loaded('mysql')) {
 227                         @dl('mysql.so');
 228                 }
 229
 230                 # Otherwise we get a suppressed fatal error, which is very hard to track down
 231                 if ( !function_exists( 'mysql_connect' ) ) {
 232                         die( "MySQL functions missing, have you compiled PHP with the --with-mysql option?\n" );
 233                 }
 234
 235                 $this->close();
 236                 $this->mServer = $server;
 237                 $this->mUser = $user;
 238                 $this->mPassword = $password;
 239                 $this->mDBname = $dbName;
 240
 241                 $success = false;
 242
 243                 if ( $this->mFlags & DBO_PERSISTENT ) {
 244                         @/**/$this->mConn = mysql_pconnect( $server, $user, $password );
 245                 } else {
 246                         # Create a new connection...
 247                         if( version_compare( PHP_VERSION, '4.2.0', 'ge' ) ) {
 248                                 @/**/$this->mConn = mysql_connect( $server, $user, $password, true );
 249                         } else {
 250                                 # On PHP 4.1 the new_link parameter is not available. We cannot
 251                                 # guarantee that we'll actually get a new connection, and this
 252                                 # may cause some operations to fail possibly.
 253                                 @/**/$this->mConn = mysql_connect( $server, $user, $password );
 254                         }
 255                 }
 256
 257                 if ( $dbName != '' ) {
 258                         if ( $this->mConn !== false ) {
 259                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 260                                 if ( !$success ) {
 261                                         wfDebug( "Error selecting database \"$dbName\": " . $this->lastError() . "\n" );
 262                                 }
 263                         } else {
 264                                 wfDebug( "DB connection error\n" );
 265                                 wfDebug( "Server: $server, User: $user, Password: " .
 266                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 267                                 $success = false;
 268                         }
 269                 } else {
 270                         # Delay USE query
 271                         $success = (bool)$this->mConn;
 272                 }
 273
 274                 if ( !$success ) {
 275                         $this->reportConnectionError();
 276                 }
 277                 $this->mOpened = $success;
 278                 return $success;
 279         }
 280         /**#@-*/
 281
 282         /**
 283          * Closes a database connection.
 284          * if it is open : commits any open transactions
 285          *
 286          * @return bool operation success. true if already closed.
 287          */
 288         function close()
 289         {
 290                 $this->mOpened = false;
 291                 if ( $this->mConn ) {
 292                         if ( $this->trxLevel() ) {
 293                                 $this->immediateCommit();
 294                         }
 295                         return mysql_close( $this->mConn );
 296                 } else {
 297                         return true;
 298                 }
 299         }
 300
 301         /**
 302          * @access private
 303          * @param string $msg error message ?
 304          */
 305         function reportConnectionError() {
 306                 if ( $this->mFailFunction ) {
 307                         if ( !is_int( $this->mFailFunction ) ) {
 308                                 $ff = $this->mFailFunction;
 309                                 $ff( $this, $this->lastError() );
 310                         }
 311                 } else {
 312                         wfEmergencyAbort( $this, $this->lastError() );
 313                 }
 314         }
 315
 316         /**
 317          * Usually aborts on failure
 318          * If errors are explicitly ignored, returns success
 319          */
 320         function query( $sql, $fname = '', $tempIgnore = false ) {
 321                 global $wgProfiling, $wgCommandLineMode;
 322
 323                 if ( wfReadOnly() ) {
 324                         # This is a quick check for the most common kinds of write query used
 325                         # in MediaWiki, to provide extra safety in addition to UI-level checks.
 326                         # It is not intended to prevent every conceivable write query, or even
 327                         # to handle such queries gracefully.
 328                         if ( preg_match( '/^(?:update|insert|replace|delete)/i', $sql ) ) {
 329                                 wfDebug( "Write query from $fname blocked\n" );
 330                                 return false;
 331                         }
 332                 }
 333
 334                 if ( $wgProfiling ) {
 335                         # generalizeSQL will probably cut down the query to reasonable
 336                         # logging size most of the time. The substr is really just a sanity check.
 337
 338                         # Who's been wasting my precious column space? -- TS
 339                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 340                         $profName = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 341
 342                         wfProfileIn( 'Database::query' );
 343                         wfProfileIn( $profName );
 344                 }
 345
 346                 $this->mLastQuery = $sql;
 347
 348                 # Add a comment for easy SHOW PROCESSLIST interpretation
 349                 if ( $fname ) {
 350                         $commentedSql = "/* $fname */ $sql";
 351                 } else {
 352                         $commentedSql = $sql;
 353                 }
 354
 355                 # If DBO_TRX is set, start a transaction
 356                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 357                         $this->begin();
 358                 }
 359
 360                 if ( $this->debug() ) {
 361                         $sqlx = substr( $commentedSql, 0, 500 );
 362                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 363                         wfDebug( "SQL: $sqlx\n" );
 364                 }
 365
 366                 # Do the query and handle errors
 367                 $ret = $this->doQuery( $commentedSql );
 368
 369                 # Try reconnecting if the connection was lost
 370                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 371                         # Transaction is gone, like it or not
 372                         $this->mTrxLevel = 0;
 373                         wfDebug( "Connection lost, reconnecting...\n" );
 374                         if ( $this->ping() ) {
 375                                 wfDebug( "Reconnected\n" );
 376                                 $ret = $this->doQuery( $commentedSql );
 377                         } else {
 378                                 wfDebug( "Failed\n" );
 379                         }
 380                 }
 381
 382                 if ( false === $ret ) {
 383                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 384                 }
 385
 386                 if ( $wgProfiling ) {
 387                         wfProfileOut( $profName );
 388                         wfProfileOut( 'Database::query' );
 389                 }
 390                 return $ret;
 391         }
 392
 393         /**
 394          * The DBMS-dependent part of query()
 395          * @param string $sql SQL query.
 396          */
 397         function doQuery( $sql ) {
 398                 if( $this->bufferResults() ) {
 399                         $ret = mysql_query( $sql, $this->mConn );
 400                 } else {
 401                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 402                 }
 403                 return $ret;
 404         }
 405
 406         /**
 407          * @param $error
 408          * @param $errno
 409          * @param $sql
 410          * @param string $fname
 411          * @param bool $tempIgnore
 412          */
 413         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 414                 global $wgCommandLineMode, $wgFullyInitialised;
 415                 # Ignore errors during error handling to avoid infinite recursion
 416                 $ignore = $this->ignoreErrors( true );
 417                 ++$this->mErrorCount;
 418
 419                 if( $ignore || $tempIgnore ) {
 420                         wfDebug("SQL ERROR (ignored): $error\n");
 421                 } else {
 422                         $sql1line = str_replace( "\n", "\\n", $sql );
 423                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 424                         wfDebug("SQL ERROR: " . $error . "\n");
 425                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 426                                 $message = "A database error has occurred\n" .
 427                                   "Query: $sql\n" .
 428                                   "Function: $fname\n" .
 429                                   "Error: $errno $error\n";
 430                                 if ( !$wgCommandLineMode ) {
 431                                         $message = nl2br( $message );
 432                                 }
 433                                 wfDebugDieBacktrace( $message );
 434                         } else {
 435                                 // this calls wfAbruptExit()
 436                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 437                         }
 438                 }
 439                 $this->ignoreErrors( $ignore );
 440         }
 441
 442
 443         /**
 444          * Intended to be compatible with the PEAR::DB wrapper functions.
 445          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 446          *
 447          * ? = scalar value, quoted as necessary
 448          * ! = raw SQL bit (a function for instance)
 449          * & = filename; reads the file and inserts as a blob
 450          *     (we don't use this though...)
 451          */
 452         function prepare( $sql, $func = 'Database::prepare' ) {
 453                 /* MySQL doesn't support prepared statements (yet), so just
 454                    pack up the query for reference. We'll manually replace
 455                    the bits later. */
 456                 return array( 'query' => $sql, 'func' => $func );
 457         }
 458
 459         function freePrepared( $prepared ) {
 460                 /* No-op for MySQL */
 461         }
 462
 463         /**
 464          * Execute a prepared query with the various arguments
 465          * @param string $prepared the prepared sql
 466          * @param mixed $args Either an array here, or put scalars as varargs
 467          */
 468         function execute( $prepared, $args = null ) {
 469                 if( !is_array( $args ) ) {
 470                         # Pull the var args
 471                         $args = func_get_args();
 472                         array_shift( $args );
 473                 }
 474                 $sql = $this->fillPrepared( $prepared['query'], $args );
 475                 return $this->query( $sql, $prepared['func'] );
 476         }
 477
 478         /**
 479          * Prepare & execute an SQL statement, quoting and inserting arguments
 480          * in the appropriate places.
 481          * @param string $query
 482          * @param string $args ...
 483          */
 484         function safeQuery( $query, $args = null ) {
 485                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 486                 if( !is_array( $args ) ) {
 487                         # Pull the var args
 488                         $args = func_get_args();
 489                         array_shift( $args );
 490                 }
 491                 $retval = $this->execute( $prepared, $args );
 492                 $this->freePrepared( $prepared );
 493                 return $retval;
 494         }
 495
 496         /**
 497          * For faking prepared SQL statements on DBs that don't support
 498          * it directly.
 499          * @param string $preparedSql - a 'preparable' SQL statement
 500          * @param array $args - array of arguments to fill it with
 501          * @return string executable SQL
 502          */
 503         function fillPrepared( $preparedQuery, $args ) {
 504                 $n = 0;
 505                 reset( $args );
 506                 $this->preparedArgs =& $args;
 507                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 508                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 509         }
 510
 511         /**
 512          * preg_callback func for fillPrepared()
 513          * The arguments should be in $this->preparedArgs and must not be touched
 514          * while we're doing this.
 515          *
 516          * @param array $matches
 517          * @return string
 518          * @access private
 519          */
 520         function fillPreparedArg( $matches ) {
 521                 switch( $matches[1] ) {
 522                         case '\\?': return '?';
 523                         case '\\!': return '!';
 524                         case '\\&': return '&';
 525                 }
 526                 list( $n, $arg ) = each( $this->preparedArgs );
 527                 switch( $matches[1] ) {
 528                         case '?': return $this->addQuotes( $arg );
 529                         case '!': return $arg;
 530                         case '&':
 531                                 # return $this->addQuotes( file_get_contents( $arg ) );
 532                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 533                         default:
 534                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 535                 }
 536         }
 537
 538         /**#@+
 539          * @param mixed $res A SQL result
 540          */
 541         /**
 542          * Free a result object
 543          */
 544         function freeResult( $res ) {
 545                 if ( !@/**/mysql_free_result( $res ) ) {
 546                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 547                 }
 548         }
 549
 550         /**
 551          * Fetch the next row from the given result object, in object form
 552          */
 553         function fetchObject( $res ) {
 554                 @/**/$row = mysql_fetch_object( $res );
 555                 if( mysql_errno() ) {
 556                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 557                 }
 558                 return $row;
 559         }
 560
 561         /**
 562          * Fetch the next row from the given result object
 563          * Returns an array
 564          */
 565         function fetchRow( $res ) {
 566                 @/**/$row = mysql_fetch_array( $res );
 567                 if (mysql_errno() ) {
 568                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 569                 }
 570                 return $row;
 571         }
 572
 573         /**
 574          * Get the number of rows in a result object
 575          */
 576         function numRows( $res ) {
 577                 @/**/$n = mysql_num_rows( $res );
 578                 if( mysql_errno() ) {
 579                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 580                 }
 581                 return $n;
 582         }
 583
 584         /**
 585          * Get the number of fields in a result object
 586          * See documentation for mysql_num_fields()
 587          */
 588         function numFields( $res ) { return mysql_num_fields( $res ); }
 589
 590         /**
 591          * Get a field name in a result object
 592          * See documentation for mysql_field_name()
 593          */
 594         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 595
 596         /**
 597          * Get the inserted value of an auto-increment row
 598          *
 599          * The value inserted should be fetched from nextSequenceValue()
 600          *
 601          * Example:
 602          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 603          * $dbw->insert('page',array('page_id' => $id));
 604          * $id = $dbw->insertId();
 605          */
 606         function insertId() { return mysql_insert_id( $this->mConn ); }
 607
 608         /**
 609          * Change the position of the cursor in a result object
 610          * See mysql_data_seek()
 611          */
 612         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 613
 614         /**
 615          * Get the last error number
 616          * See mysql_errno()
 617          */
 618         function lastErrno() {
 619                 if ( $this->mConn ) {
 620                         return mysql_errno( $this->mConn );
 621                 } else {
 622                         return mysql_errno();
 623                 }
 624         }
 625
 626         /**
 627          * Get a description of the last error
 628          * See mysql_error() for more details
 629          */
 630         function lastError() {
 631                 if ( $this->mConn ) {
 632                         # Even if it's non-zero, it can still be invalid
 633                         wfSuppressWarnings();
 634                         $error = mysql_error( $this->mConn );
 635                         if ( !$error ) {
 636                                 $error = mysql_error();
 637                         }
 638                         wfRestoreWarnings();
 639                 } else {
 640                         $error = mysql_error();
 641                 }
 642                 if( $error ) {
 643                         $error .= ' (' . $this->mServer . ')';
 644                 }
 645                 return $error;
 646         }
 647         /**
 648          * Get the number of rows affected by the last write query
 649          * See mysql_affected_rows() for more details
 650          */
 651         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 652         /**#@-*/ // end of template : @param $result
 653
 654         /**
 655          * Simple UPDATE wrapper
 656          * Usually aborts on failure
 657          * If errors are explicitly ignored, returns success
 658          *
 659          * This function exists for historical reasons, Database::update() has a more standard
 660          * calling convention and feature set
 661          */
 662         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 663         {
 664                 $table = $this->tableName( $table );
 665                 $sql = "UPDATE $table SET $var = '" .
 666                   $this->strencode( $value ) . "' WHERE ($cond)";
 667                 return (bool)$this->query( $sql, DB_MASTER, $fname );
 668         }
 669
 670         /**
 671          * Simple SELECT wrapper, returns a single field, input must be encoded
 672          * Usually aborts on failure
 673          * If errors are explicitly ignored, returns FALSE on failure
 674          */
 675         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 676                 if ( !is_array( $options ) ) {
 677                         $options = array( $options );
 678                 }
 679                 $options['LIMIT'] = 1;
 680
 681                 $res = $this->select( $table, $var, $cond, $fname, $options );
 682                 if ( $res === false || !$this->numRows( $res ) ) {
 683                         return false;
 684                 }
 685                 $row = $this->fetchRow( $res );
 686                 if ( $row !== false ) {
 687                         $this->freeResult( $res );
 688                         return $row[0];
 689                 } else {
 690                         return false;
 691                 }
 692         }
 693
 694         /**
 695          * Returns an optional USE INDEX clause to go after the table, and a
 696          * string to go at the end of the query
 697          *
 698          * @access private
 699          *
 700          * @param array $options an associative array of options to be turned into
 701          *              an SQL query, valid keys are listed in the function.
 702          * @return array
 703          */
 704         function makeSelectOptions( $options ) {
 705                 $tailOpts = '';
 706
 707                 if ( isset( $options['GROUP BY'] ) ) {
 708                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 709                 }
 710                 if ( isset( $options['ORDER BY'] ) ) {
 711                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 712                 }
 713                 if (isset($options['LIMIT'])) {
 714                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 715                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 716                 }
 717                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 718                         $tailOpts .= ' FOR UPDATE';
 719                 }
 720
 721                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 722                         $tailOpts .= ' LOCK IN SHARE MODE';
 723                 }
 724
 725                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 726                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 727                 } else {
 728                         $useIndex = '';
 729                 }
 730                 return array( $useIndex, $tailOpts );
 731         }
 732
 733         /**
 734          * SELECT wrapper
 735          */
 736         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 737         {
 738                 if( is_array( $vars ) ) {
 739                         $vars = implode( ',', $vars );
 740                 }
 741                 if( !is_array( $options ) ) {
 742                         $options = array( $options );
 743                 }
 744                 if( is_array( $table ) ) {
 745                         if ( @is_array( $options['USE INDEX'] ) )
 746                                 $from = ' FROM ' . $this->tableNamesWithUseIndex( $table, $options['USE INDEX'] );
 747                         else
 748                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 749                 } elseif ($table!='') {
 750                         $from = ' FROM ' . $this->tableName( $table );
 751                 } else {
 752                         $from = '';
 753                 }
 754
 755                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 756
 757                 if( !empty( $conds ) ) {
 758                         if ( is_array( $conds ) ) {
 759                                 $conds = $this->makeList( $conds, LIST_AND );
 760                         }
 761                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 762                 } else {
 763                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 764                 }
 765
 766                 return $this->query( $sql, $fname );
 767         }
 768
 769         /**
 770          * Single row SELECT wrapper
 771          * Aborts or returns FALSE on error
 772          *
 773          * $vars: the selected variables
 774          * $conds: a condition map, terms are ANDed together.
 775          *   Items with numeric keys are taken to be literal conditions
 776          * Takes an array of selected variables, and a condition map, which is ANDed
 777          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 778          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 779          * $obj- >page_id is the ID of the Astronomy article
 780          *
 781          * @todo migrate documentation to phpdocumentor format
 782          */
 783         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 784                 $options['LIMIT'] = 1;
 785                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 786                 if ( $res === false )
 787                         return false;
 788                 if ( !$this->numRows($res) ) {
 789                         $this->freeResult($res);
 790                         return false;
 791                 }
 792                 $obj = $this->fetchObject( $res );
 793                 $this->freeResult( $res );
 794                 return $obj;
 795
 796         }
 797
 798         /**
 799          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 800          * It's only slightly flawed. Don't use for anything important.
 801          *
 802          * @param string $sql A SQL Query
 803          * @static
 804          */
 805         function generalizeSQL( $sql ) {
 806                 # This does the same as the regexp below would do, but in such a way
 807                 # as to avoid crashing php on some large strings.
 808                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 809
 810                 $sql = str_replace ( "\\\\", '', $sql);
 811                 $sql = str_replace ( "\\'", '', $sql);
 812                 $sql = str_replace ( "\\\"", '', $sql);
 813                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 814                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 815
 816                 # All newlines, tabs, etc replaced by single space
 817                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 818
 819                 # All numbers => N
 820                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 821
 822                 return $sql;
 823         }
 824
 825         /**
 826          * Determines whether a field exists in a table
 827          * Usually aborts on failure
 828          * If errors are explicitly ignored, returns NULL on failure
 829          */
 830         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 831                 $table = $this->tableName( $table );
 832                 $res = $this->query( 'DESCRIBE '.$table, DB_SLAVE, $fname );
 833                 if ( !$res ) {
 834                         return NULL;
 835                 }
 836
 837                 $found = false;
 838
 839                 while ( $row = $this->fetchObject( $res ) ) {
 840                         if ( $row->Field == $field ) {
 841                                 $found = true;
 842                                 break;
 843                         }
 844                 }
 845                 return $found;
 846         }
 847
 848         /**
 849          * Determines whether an index exists
 850          * Usually aborts on failure
 851          * If errors are explicitly ignored, returns NULL on failure
 852          */
 853         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 854                 $info = $this->indexInfo( $table, $index, $fname );
 855                 if ( is_null( $info ) ) {
 856                         return NULL;
 857                 } else {
 858                         return $info !== false;
 859                 }
 860         }
 861
 862
 863         /**
 864          * Get information about an index into an object
 865          * Returns false if the index does not exist
 866          */
 867         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 868                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 869                 # SHOW INDEX should work for 3.x and up:
 870                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 871                 $table = $this->tableName( $table );
 872                 $sql = 'SHOW INDEX FROM '.$table;
 873                 $res = $this->query( $sql, $fname );
 874                 if ( !$res ) {
 875                         return NULL;
 876                 }
 877
 878                 while ( $row = $this->fetchObject( $res ) ) {
 879                         if ( $row->Key_name == $index ) {
 880                                 return $row;
 881                         }
 882                 }
 883                 return false;
 884         }
 885
 886         /**
 887          * Query whether a given table exists
 888          */
 889         function tableExists( $table ) {
 890                 $table = $this->tableName( $table );
 891                 $old = $this->ignoreErrors( true );
 892                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 893                 $this->ignoreErrors( $old );
 894                 if( $res ) {
 895                         $this->freeResult( $res );
 896                         return true;
 897                 } else {
 898                         return false;
 899                 }
 900         }
 901
 902         /**
 903          * mysql_fetch_field() wrapper
 904          * Returns false if the field doesn't exist
 905          *
 906          * @param $table
 907          * @param $field
 908          */
 909         function fieldInfo( $table, $field ) {
 910                 $table = $this->tableName( $table );
 911                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 912                 $n = mysql_num_fields( $res );
 913                 for( $i = 0; $i < $n; $i++ ) {
 914                         $meta = mysql_fetch_field( $res, $i );
 915                         if( $field == $meta->name ) {
 916                                 return $meta;
 917                         }
 918                 }
 919                 return false;
 920         }
 921
 922         /**
 923          * mysql_field_type() wrapper
 924          */
 925         function fieldType( $res, $index ) {
 926                 return mysql_field_type( $res, $index );
 927         }
 928
 929         /**
 930          * Determines if a given index is unique
 931          */
 932         function indexUnique( $table, $index ) {
 933                 $indexInfo = $this->indexInfo( $table, $index );
 934                 if ( !$indexInfo ) {
 935                         return NULL;
 936                 }
 937                 return !$indexInfo->Non_unique;
 938         }
 939
 940         /**
 941          * INSERT wrapper, inserts an array into a table
 942          *
 943          * $a may be a single associative array, or an array of these with numeric keys, for
 944          * multi-row insert.
 945          *
 946          * Usually aborts on failure
 947          * If errors are explicitly ignored, returns success
 948          */
 949         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 950                 # No rows to insert, easy just return now
 951                 if ( !count( $a ) ) {
 952                         return true;
 953                 }
 954
 955                 $table = $this->tableName( $table );
 956                 if ( !is_array( $options ) ) {
 957                         $options = array( $options );
 958                 }
 959                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
 960                         $multi = true;
 961                         $keys = array_keys( $a[0] );
 962                 } else {
 963                         $multi = false;
 964                         $keys = array_keys( $a );
 965                 }
 966
 967                 $sql = 'INSERT ' . implode( ' ', $options ) .
 968                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 969
 970                 if ( $multi ) {
 971                         $first = true;
 972                         foreach ( $a as $row ) {
 973                                 if ( $first ) {
 974                                         $first = false;
 975                                 } else {
 976                                         $sql .= ',';
 977                                 }
 978                                 $sql .= '(' . $this->makeList( $row ) . ')';
 979                         }
 980                 } else {
 981                         $sql .= '(' . $this->makeList( $a ) . ')';
 982                 }
 983                 return (bool)$this->query( $sql, $fname );
 984         }
 985
 986         /**
 987          * Make UPDATE options for the Database::update function
 988          *
 989          * @access private
 990          * @param array $options The options passed to Database::update
 991          * @return string
 992          */
 993         function makeUpdateOptions( $options ) {
 994                 if( !is_array( $options ) ) {
 995                         $options = array( $options );
 996                 }
 997                 $opts = array();
 998                 if ( in_array( 'LOW_PRIORITY', $options ) )
 999                         $opts[] = $this->lowPriorityOption();
1000                 if ( in_array( 'IGNORE', $options ) )
1001                         $opts[] = 'IGNORE';
1002                 return implode(' ', $opts);
1003         }
1004
1005         /**
1006          * UPDATE wrapper, takes a condition array and a SET array
1007          *
1008          * @param string $table  The table to UPDATE
1009          * @param array  $values An array of values to SET
1010          * @param array  $conds  An array of conditions (WHERE)
1011          * @param string $fname  The Class::Function calling this function
1012          *                       (for the log)
1013          * @param array  $options An array of UPDATE options, can be one or
1014          *                        more of IGNORE, LOW_PRIORITY
1015          */
1016         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1017                 $table = $this->tableName( $table );
1018                 $opts = $this->makeUpdateOptions( $options );
1019                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1020                 if ( $conds != '*' ) {
1021                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1022                 }
1023                 $this->query( $sql, $fname );
1024         }
1025
1026         /**
1027          * Makes a wfStrencoded list from an array
1028          * $mode: LIST_COMMA         - comma separated, no field names
1029          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1030          *        LIST_SET           - comma separated with field names, like a SET clause
1031          *        LIST_NAMES         - comma separated field names
1032          */
1033         function makeList( $a, $mode = LIST_COMMA ) {
1034                 if ( !is_array( $a ) ) {
1035                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1036                 }
1037
1038                 $first = true;
1039                 $list = '';
1040                 foreach ( $a as $field => $value ) {
1041                         if ( !$first ) {
1042                                 if ( $mode == LIST_AND ) {
1043                                         $list .= ' AND ';
1044                                 } elseif($mode == LIST_OR) {
1045                                         $list .= ' OR ';
1046                                 } else {
1047                                         $list .= ',';
1048                                 }
1049                         } else {
1050                                 $first = false;
1051                         }
1052                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1053                                 $list .= "($value)";
1054                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1055                                 $list .= $field." IN (".$this->makeList($value).") ";
1056                         } else {
1057                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1058                                         $list .= "$field = ";
1059                                 }
1060                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1061                         }
1062                 }
1063                 return $list;
1064         }
1065
1066         /**
1067          * Change the current database
1068          */
1069         function selectDB( $db ) {
1070                 $this->mDBname = $db;
1071                 return mysql_select_db( $db, $this->mConn );
1072         }
1073
1074         /**
1075          * Starts a timer which will kill the DB thread after $timeout seconds
1076          */
1077         function startTimer( $timeout ) {
1078                 global $IP;
1079                 if( function_exists( 'mysql_thread_id' ) ) {
1080                         # This will kill the query if it's still running after $timeout seconds.
1081                         $tid = mysql_thread_id( $this->mConn );
1082                         exec( "php $IP/includes/killthread.php $timeout $tid &>/dev/null &" );
1083                 }
1084         }
1085
1086         /**
1087          * Stop a timer started by startTimer()
1088          * Currently unimplemented.
1089          *
1090          */
1091         function stopTimer() { }
1092
1093         /**
1094          * Format a table name ready for use in constructing an SQL query
1095          *
1096          * This does two important things: it quotes table names which as necessary,
1097          * and it adds a table prefix if there is one.
1098          *
1099          * All functions of this object which require a table name call this function
1100          * themselves. Pass the canonical name to such functions. This is only needed
1101          * when calling query() directly.
1102          *
1103          * @param string $name database table name
1104          */
1105         function tableName( $name ) {
1106                 global $wgSharedDB;
1107                 # Skip quoted literals
1108                 if ( $name{0} != '`' ) {
1109                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1110                                 $name = "{$this->mTablePrefix}$name";
1111                         }
1112                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1113                                 $name = "`$wgSharedDB`.`$name`";
1114                         } else {
1115                                 # Standard quoting
1116                                 $name = "`$name`";
1117                         }
1118                 }
1119                 return $name;
1120         }
1121
1122         /**
1123          * Fetch a number of table names into an array
1124          * This is handy when you need to construct SQL for joins
1125          *
1126          * Example:
1127          * extract($dbr->tableNames('user','watchlist'));
1128          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1129          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1130          */
1131         function tableNames() {
1132                 $inArray = func_get_args();
1133                 $retVal = array();
1134                 foreach ( $inArray as $name ) {
1135                         $retVal[$name] = $this->tableName( $name );
1136                 }
1137                 return $retVal;
1138         }
1139
1140         /**
1141          * @access private
1142          */
1143         function tableNamesWithUseIndex( $tables, $use_index ) {
1144                 $ret = array();
1145
1146                 foreach ( $tables as $table )
1147                         if ( @$use_index[$table] !== null )
1148                                 $ret[] = $this->tableName( $table ) . ' ' . $this->useIndexClause( implode( ',', (array)$use_index[$table] ) );
1149                         else
1150                                 $ret[] = $this->tableName( $table );
1151
1152                 return implode( ',', $ret );
1153         }
1154
1155         /**
1156          * Wrapper for addslashes()
1157          * @param string $s String to be slashed.
1158          * @return string slashed string.
1159          */
1160         function strencode( $s ) {
1161                 return addslashes( $s );
1162         }
1163
1164         /**
1165          * If it's a string, adds quotes and backslashes
1166          * Otherwise returns as-is
1167          */
1168         function addQuotes( $s ) {
1169                 if ( is_null( $s ) ) {
1170                         return 'NULL';
1171                 } else {
1172                         # This will also quote numeric values. This should be harmless,
1173                         # and protects against weird problems that occur when they really
1174                         # _are_ strings such as article titles and string->number->string
1175                         # conversion is not 1:1.
1176                         return "'" . $this->strencode( $s ) . "'";
1177                 }
1178         }
1179
1180         /**
1181          * Escape string for safe LIKE usage
1182          */
1183         function escapeLike( $s ) {
1184                 $s=$this->strencode( $s );
1185                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1186                 return $s;
1187         }
1188
1189         /**
1190          * Returns an appropriately quoted sequence value for inserting a new row.
1191          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1192          * subclass will return an integer, and save the value for insertId()
1193          */
1194         function nextSequenceValue( $seqName ) {
1195                 return NULL;
1196         }
1197
1198         /**
1199          * USE INDEX clause
1200          * PostgreSQL doesn't have them and returns ""
1201          */
1202         function useIndexClause( $index ) {
1203                 return "FORCE INDEX ($index)";
1204         }
1205
1206         /**
1207          * REPLACE query wrapper
1208          * PostgreSQL simulates this with a DELETE followed by INSERT
1209          * $row is the row to insert, an associative array
1210          * $uniqueIndexes is an array of indexes. Each element may be either a
1211          * field name or an array of field names
1212          *
1213          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1214          * However if you do this, you run the risk of encountering errors which wouldn't have
1215          * occurred in MySQL
1216          *
1217          * @todo migrate comment to phodocumentor format
1218          */
1219         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1220                 $table = $this->tableName( $table );
1221
1222                 # Single row case
1223                 if ( !is_array( reset( $rows ) ) ) {
1224                         $rows = array( $rows );
1225                 }
1226
1227                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1228                 $first = true;
1229                 foreach ( $rows as $row ) {
1230                         if ( $first ) {
1231                                 $first = false;
1232                         } else {
1233                                 $sql .= ',';
1234                         }
1235                         $sql .= '(' . $this->makeList( $row ) . ')';
1236                 }
1237                 return $this->query( $sql, $fname );
1238         }
1239
1240         /**
1241          * DELETE where the condition is a join
1242          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1243          *
1244          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1245          * join condition matches, set $conds='*'
1246          *
1247          * DO NOT put the join condition in $conds
1248          *
1249          * @param string $delTable The table to delete from.
1250          * @param string $joinTable The other table.
1251          * @param string $delVar The variable to join on, in the first table.
1252          * @param string $joinVar The variable to join on, in the second table.
1253          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1254          */
1255         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1256                 if ( !$conds ) {
1257                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1258                 }
1259
1260                 $delTable = $this->tableName( $delTable );
1261                 $joinTable = $this->tableName( $joinTable );
1262                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1263                 if ( $conds != '*' ) {
1264                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1265                 }
1266
1267                 return $this->query( $sql, $fname );
1268         }
1269
1270         /**
1271          * Returns the size of a text field, or -1 for "unlimited"
1272          */
1273         function textFieldSize( $table, $field ) {
1274                 $table = $this->tableName( $table );
1275                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1276                 $res = $this->query( $sql, 'Database::textFieldSize' );
1277                 $row = $this->fetchObject( $res );
1278                 $this->freeResult( $res );
1279
1280                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1281                         $size = $m[1];
1282                 } else {
1283                         $size = -1;
1284                 }
1285                 return $size;
1286         }
1287
1288         /**
1289          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1290          */
1291         function lowPriorityOption() {
1292                 return 'LOW_PRIORITY';
1293         }
1294
1295         /**
1296          * DELETE query wrapper
1297          *
1298          * Use $conds == "*" to delete all rows
1299          */
1300         function delete( $table, $conds, $fname = 'Database::delete' ) {
1301                 if ( !$conds ) {
1302                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1303                 }
1304                 $table = $this->tableName( $table );
1305                 $sql = "DELETE FROM $table";
1306                 if ( $conds != '*' ) {
1307                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1308                 }
1309                 return $this->query( $sql, $fname );
1310         }
1311
1312         /**
1313          * INSERT SELECT wrapper
1314          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1315          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1316          * $conds may be "*" to copy the whole table
1317          * srcTable may be an array of tables.
1318          */
1319         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect' ) {
1320                 $destTable = $this->tableName( $destTable );
1321                 if( is_array( $srcTable ) ) {
1322                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1323                 } else {
1324                         $srcTable = $this->tableName( $srcTable );
1325                 }
1326                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1327                         ' SELECT ' . implode( ',', $varMap ) .
1328                         " FROM $srcTable";
1329                 if ( $conds != '*' ) {
1330                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1331                 }
1332                 return $this->query( $sql, $fname );
1333         }
1334
1335         /**
1336          * Construct a LIMIT query with optional offset
1337          * This is used for query pages
1338          * $sql string SQL query we will append the limit too
1339          * $limit integer the SQL limit
1340          * $offset integer the SQL offset (default false)
1341          */
1342         function limitResult($sql, $limit, $offset=false) {
1343                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1344         }
1345         function limitResultForUpdate($sql, $num) {
1346                 return $this->limitResult($sql, $num, 0);
1347         }
1348
1349         /**
1350          * Returns an SQL expression for a simple conditional.
1351          * Uses IF on MySQL.
1352          *
1353          * @param string $cond SQL expression which will result in a boolean value
1354          * @param string $trueVal SQL expression to return if true
1355          * @param string $falseVal SQL expression to return if false
1356          * @return string SQL fragment
1357          */
1358         function conditional( $cond, $trueVal, $falseVal ) {
1359                 return " IF($cond, $trueVal, $falseVal) ";
1360         }
1361
1362         /**
1363          * Determines if the last failure was due to a deadlock
1364          */
1365         function wasDeadlock() {
1366                 return $this->lastErrno() == 1213;
1367         }
1368
1369         /**
1370          * Perform a deadlock-prone transaction.
1371          *
1372          * This function invokes a callback function to perform a set of write
1373          * queries. If a deadlock occurs during the processing, the transaction
1374          * will be rolled back and the callback function will be called again.
1375          *
1376          * Usage:
1377          *   $dbw->deadlockLoop( callback, ... );
1378          *
1379          * Extra arguments are passed through to the specified callback function.
1380          *
1381          * Returns whatever the callback function returned on its successful,
1382          * iteration, or false on error, for example if the retry limit was
1383          * reached.
1384          */
1385         function deadlockLoop() {
1386                 $myFname = 'Database::deadlockLoop';
1387
1388                 $this->begin();
1389                 $args = func_get_args();
1390                 $function = array_shift( $args );
1391                 $oldIgnore = $this->ignoreErrors( true );
1392                 $tries = DEADLOCK_TRIES;
1393                 if ( is_array( $function ) ) {
1394                         $fname = $function[0];
1395                 } else {
1396                         $fname = $function;
1397                 }
1398                 do {
1399                         $retVal = call_user_func_array( $function, $args );
1400                         $error = $this->lastError();
1401                         $errno = $this->lastErrno();
1402                         $sql = $this->lastQuery();
1403
1404                         if ( $errno ) {
1405                                 if ( $this->wasDeadlock() ) {
1406                                         # Retry
1407                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1408                                 } else {
1409                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1410                                 }
1411                         }
1412                 } while( $this->wasDeadlock() && --$tries > 0 );
1413                 $this->ignoreErrors( $oldIgnore );
1414                 if ( $tries <= 0 ) {
1415                         $this->query( 'ROLLBACK', $myFname );
1416                         $this->reportQueryError( $error, $errno, $sql, $fname );
1417                         return false;
1418                 } else {
1419                         $this->query( 'COMMIT', $myFname );
1420                         return $retVal;
1421                 }
1422         }
1423
1424         /**
1425          * Do a SELECT MASTER_POS_WAIT()
1426          *
1427          * @param string $file the binlog file
1428          * @param string $pos the binlog position
1429          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1430          */
1431         function masterPosWait( $file, $pos, $timeout ) {
1432                 $fname = 'Database::masterPosWait';
1433                 wfProfileIn( $fname );
1434
1435
1436                 # Commit any open transactions
1437                 $this->immediateCommit();
1438
1439                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1440                 $encFile = $this->strencode( $file );
1441                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1442                 $res = $this->doQuery( $sql );
1443                 if ( $res && $row = $this->fetchRow( $res ) ) {
1444                         $this->freeResult( $res );
1445                         wfProfileOut( $fname );
1446                         return $row[0];
1447                 } else {
1448                         wfProfileOut( $fname );
1449                         return false;
1450                 }
1451         }
1452
1453         /**
1454          * Get the position of the master from SHOW SLAVE STATUS
1455          */
1456         function getSlavePos() {
1457                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1458                 $row = $this->fetchObject( $res );
1459                 if ( $row ) {
1460                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1461                 } else {
1462                         return array( false, false );
1463                 }
1464         }
1465
1466         /**
1467          * Get the position of the master from SHOW MASTER STATUS
1468          */
1469         function getMasterPos() {
1470                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1471                 $row = $this->fetchObject( $res );
1472                 if ( $row ) {
1473                         return array( $row->File, $row->Position );
1474                 } else {
1475                         return array( false, false );
1476                 }
1477         }
1478
1479         /**
1480          * Begin a transaction, or if a transaction has already started, continue it
1481          */
1482         function begin( $fname = 'Database::begin' ) {
1483                 if ( !$this->mTrxLevel ) {
1484                         $this->immediateBegin( $fname );
1485                 } else {
1486                         $this->mTrxLevel++;
1487                 }
1488         }
1489
1490         /**
1491          * End a transaction, or decrement the nest level if transactions are nested
1492          */
1493         function commit( $fname = 'Database::commit' ) {
1494                 if ( $this->mTrxLevel ) {
1495                         $this->mTrxLevel--;
1496                 }
1497                 if ( !$this->mTrxLevel ) {
1498                         $this->immediateCommit( $fname );
1499                 }
1500         }
1501
1502         /**
1503          * Rollback a transaction
1504          */
1505         function rollback( $fname = 'Database::rollback' ) {
1506                 $this->query( 'ROLLBACK', $fname );
1507                 $this->mTrxLevel = 0;
1508         }
1509
1510         /**
1511          * Begin a transaction, committing any previously open transaction
1512          */
1513         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1514                 $this->query( 'BEGIN', $fname );
1515                 $this->mTrxLevel = 1;
1516         }
1517
1518         /**
1519          * Commit transaction, if one is open
1520          */
1521         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1522                 $this->query( 'COMMIT', $fname );
1523                 $this->mTrxLevel = 0;
1524         }
1525
1526         /**
1527          * Return MW-style timestamp used for MySQL schema
1528          */
1529         function timestamp( $ts=0 ) {
1530                 return wfTimestamp(TS_MW,$ts);
1531         }
1532
1533         /**
1534          * Local database timestamp format or null
1535          */
1536         function timestampOrNull( $ts = null ) {
1537                 if( is_null( $ts ) ) {
1538                         return null;
1539                 } else {
1540                         return $this->timestamp( $ts );
1541                 }
1542         }
1543
1544         /**
1545          * @todo document
1546          */
1547         function resultObject( $result ) {
1548                 if( empty( $result ) ) {
1549                         return NULL;
1550                 } else {
1551                         return new ResultWrapper( $this, $result );
1552                 }
1553         }
1554
1555         /**
1556          * Return aggregated value alias
1557          */
1558         function aggregateValue ($valuedata,$valuename='value') {
1559                 return $valuename;
1560         }
1561
1562         /**
1563          * @return string wikitext of a link to the server software's web site
1564          */
1565         function getSoftwareLink() {
1566                 return "[http://www.mysql.com/ MySQL]";
1567         }
1568
1569         /**
1570          * @return string Version information from the database
1571          */
1572         function getServerVersion() {
1573                 return mysql_get_server_info();
1574         }
1575
1576         /**
1577          * Ping the server and try to reconnect if it there is no connection
1578          */
1579         function ping() {
1580                 if( function_exists( 'mysql_ping' ) ) {
1581                         return mysql_ping( $this->mConn );
1582                 } else {
1583                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1584                         return true;
1585                 }
1586         }
1587
1588         /**
1589          * Get slave lag.
1590          * At the moment, this will only work if the DB user has the PROCESS privilege
1591          */
1592         function getLag() {
1593                 $res = $this->query( 'SHOW PROCESSLIST' );
1594                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1595                 # dubious, but unfortunately there's no easy rigorous way
1596                 $slaveThreads = 0;
1597                 while ( $row = $this->fetchObject( $res ) ) {
1598                         if ( $row->User == 'system user' ) {
1599                                 if ( ++$slaveThreads == 2 ) {
1600                                         # This is it, return the time
1601                                         return $row->Time;
1602                                 }
1603                         }
1604                 }
1605                 return false;
1606         }
1607
1608         /**
1609          * Get status information from SHOW STATUS in an associative array
1610          */
1611         function getStatus() {
1612                 $res = $this->query( 'SHOW STATUS' );
1613                 $status = array();
1614                 while ( $row = $this->fetchObject( $res ) ) {
1615                         $status[$row->Variable_name] = $row->Value;
1616                 }
1617                 return $status;
1618         }
1619
1620         /**
1621          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1622          */
1623         function maxListLen() {
1624                 return 0;
1625         }
1626
1627         function encodeBlob($b) {
1628                 return $b;
1629         }
1630
1631         function notNullTimestamp() {
1632                 return "!= 0";
1633         }
1634         function isNullTimestamp() {
1635                 return "= '0'";
1636         }
1637 }
1638
1639 /**
1640  * Database abstraction object for mySQL
1641  * Inherit all methods and properties of Database::Database()
1642  *
1643  * @package MediaWiki
1644  * @see Database
1645  */
1646 class DatabaseMysql extends Database {
1647         # Inherit all
1648 }
1649
1650
1651 /**
1652  * Result wrapper for grabbing data queried by someone else
1653  *
1654  * @package MediaWiki
1655  */
1656 class ResultWrapper {
1657         var $db, $result;
1658
1659         /**
1660          * @todo document
1661          */
1662         function ResultWrapper( $database, $result ) {
1663                 $this->db =& $database;
1664                 $this->result =& $result;
1665         }
1666
1667         /**
1668          * @todo document
1669          */
1670         function numRows() {
1671                 return $this->db->numRows( $this->result );
1672         }
1673
1674         /**
1675          * @todo document
1676          */
1677         function fetchObject() {
1678                 return $this->db->fetchObject( $this->result );
1679         }
1680
1681         /**
1682          * @todo document
1683          */
1684         function &fetchRow() {
1685                 return $this->db->fetchRow( $this->result );
1686         }
1687
1688         /**
1689          * @todo document
1690          */
1691         function free() {
1692                 $this->db->freeResult( $this->result );
1693                 unset( $this->result );
1694                 unset( $this->db );
1695         }
1696
1697         function seek( $row ) {
1698                 $this->db->dataSeek( $this->result, $row );
1699         }
1700 }
1701
1702 #------------------------------------------------------------------------------
1703 # Global functions
1704 #------------------------------------------------------------------------------
1705
1706 /**
1707  * Standard fail function, called by default when a connection cannot be
1708  * established.
1709  * Displays the file cache if possible
1710  */
1711 function wfEmergencyAbort( &$conn, $error ) {
1712         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1713         global $wgSitename, $wgServer, $wgMessageCache, $wgLogo;
1714
1715         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1716         # Hard coding strings instead.
1717
1718         $noconnect = "<h1><img src='$wgLogo' style='float:left;margin-right:1em' alt=''>$wgSitename has a problem</h1><p><strong>Sorry! This site is experiencing technical difficulties.</strong></p><p>Try waiting a few minutes and reloading.</p><p><small>(Can't contact the database server: $1)</small></p>";
1719         $mainpage = 'Main Page';
1720         $searchdisabled = <<<EOT
1721 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1722 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1723 EOT;
1724
1725         $googlesearch = "
1726 <!-- SiteSearch Google -->
1727 <FORM method=GET action=\"http://www.google.com/search\">
1728 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1729 <A HREF=\"http://www.google.com/\">
1730 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1731 border=\"0\" ALT=\"Google\"></A>
1732 </td>
1733 <td>
1734 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1735 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1736 <font size=-1>
1737 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1738 <input type='hidden' name='ie' value='$2'>
1739 <input type='hidden' name='oe' value='$2'>
1740 </font>
1741 </td></tr></TABLE>
1742 </FORM>
1743 <!-- SiteSearch Google -->";
1744         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1745
1746
1747         if( !headers_sent() ) {
1748                 header( 'HTTP/1.0 500 Internal Server Error' );
1749                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1750                 /* Don't cache error pages!  They cause no end of trouble... */
1751                 header( 'Cache-control: none' );
1752                 header( 'Pragma: nocache' );
1753         }
1754
1755         # No database access
1756         if ( is_object( $wgMessageCache ) ) {
1757                 $wgMessageCache->disable();
1758         }
1759
1760         $msg = wfGetSiteNotice();
1761         if($msg == '') {
1762                 $msg = str_replace( '$1', $error, $noconnect );
1763         }
1764         $text = $msg;
1765
1766         if($wgUseFileCache) {
1767                 if($wgTitle) {
1768                         $t =& $wgTitle;
1769                 } else {
1770                         if($title) {
1771                                 $t = Title::newFromURL( $title );
1772                         } elseif (@/**/$_REQUEST['search']) {
1773                                 $search = $_REQUEST['search'];
1774                                 echo $searchdisabled;
1775                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1776                                   $wgInputEncoding ), $googlesearch );
1777                                 wfErrorExit();
1778                         } else {
1779                                 $t = Title::newFromText( $mainpage );
1780                         }
1781                 }
1782
1783                 $cache = new CacheManager( $t );
1784                 if( $cache->isFileCached() ) {
1785                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1786                                 $cachederror . "</b></p>\n";
1787
1788                         $tag = '<div id="article">';
1789                         $text = str_replace(
1790                                 $tag,
1791                                 $tag . $msg,
1792                                 $cache->fetchPageText() );
1793                 }
1794         }
1795
1796         echo $text;
1797         wfErrorExit();
1798 }
1799
1800 ?>