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