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                 global $wguname;
 225
 226                 # Test for missing mysql.so
 227                 # First try to load it
 228                 if (!@extension_loaded('mysql')) {
 229                         @dl('mysql.so');
 230                 }
 231
 232                 # Otherwise we get a suppressed fatal error, which is very hard to track down
 233                 if ( !function_exists( 'mysql_connect' ) ) {
 234                         die( "MySQL functions missing, have you compiled PHP with the --with-mysql option?\n" );
 235                 }
 236
 237                 $this->close();
 238                 $this->mServer = $server;
 239                 $this->mUser = $user;
 240                 $this->mPassword = $password;
 241                 $this->mDBname = $dbName;
 242
 243                 $success = false;
 244
 245                 if ( $this->mFlags & DBO_PERSISTENT ) {
 246                         @/**/$this->mConn = mysql_pconnect( $server, $user, $password );
 247                 } else {
 248                         # Create a new connection...
 249                         if( version_compare( PHP_VERSION, '4.2.0', 'ge' ) ) {
 250                                 @/**/$this->mConn = mysql_connect( $server, $user, $password, true );
 251                         } else {
 252                                 # On PHP 4.1 the new_link parameter is not available. We cannot
 253                                 # guarantee that we'll actually get a new connection, and this
 254                                 # may cause some operations to fail possibly.
 255                                 @/**/$this->mConn = mysql_connect( $server, $user, $password );
 256                         }
 257                 }
 258
 259                 if ( $dbName != '' ) {
 260                         if ( $this->mConn !== false ) {
 261                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 262                                 if ( !$success ) {
 263                                         $error = "Error selecting database $dbname on server {$this->mServer} " .
 264                                                 "from client host {$wguname['nodename']}\n";
 265                                         wfDebug( $error );
 266                                 }
 267                         } else {
 268                                 wfDebug( "DB connection error\n" );
 269                                 wfDebug( "Server: $server, User: $user, Password: " .
 270                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 271                                 $success = false;
 272                         }
 273                 } else {
 274                         # Delay USE query
 275                         $success = (bool)$this->mConn;
 276                 }
 277
 278                 if ( !$success ) {
 279                         $this->reportConnectionError();
 280                 }
 281
 282                 global $wgDBmysql5;
 283                 if( $wgDBmysql5 ) {
 284                         // Tell the server we're communicating with it in UTF-8.
 285                         // This may engage various charset conversions.
 286                         $this->query( 'SET NAMES utf8' );
 287                 }
 288
 289                 $this->mOpened = $success;
 290                 return $success;
 291         }
 292         /**#@-*/
 293
 294         /**
 295          * Closes a database connection.
 296          * if it is open : commits any open transactions
 297          *
 298          * @return bool operation success. true if already closed.
 299          */
 300         function close()
 301         {
 302                 $this->mOpened = false;
 303                 if ( $this->mConn ) {
 304                         if ( $this->trxLevel() ) {
 305                                 $this->immediateCommit();
 306                         }
 307                         return mysql_close( $this->mConn );
 308                 } else {
 309                         return true;
 310                 }
 311         }
 312
 313         /**
 314          * @access private
 315          * @param string $error fallback error message, used if none is given by MySQL
 316          */
 317         function reportConnectionError( $error = 'Unknown error' ) {
 318                 $myError = $this->lastError();
 319                 if ( $myError ) {
 320                         $error = $myError;
 321                 }
 322
 323                 if ( $this->mFailFunction ) {
 324                         if ( !is_int( $this->mFailFunction ) ) {
 325                                 $ff = $this->mFailFunction;
 326                                 $ff( $this, $error );
 327                         }
 328                 } else {
 329                         wfEmergencyAbort( $this, $error );
 330                 }
 331         }
 332
 333         /**
 334          * Usually aborts on failure
 335          * If errors are explicitly ignored, returns success
 336          */
 337         function query( $sql, $fname = '', $tempIgnore = false ) {
 338                 global $wgProfiling, $wgCommandLineMode;
 339
 340                 if ( wfReadOnly() ) {
 341                         # This is a quick check for the most common kinds of write query used
 342                         # in MediaWiki, to provide extra safety in addition to UI-level checks.
 343                         # It is not intended to prevent every conceivable write query, or even
 344                         # to handle such queries gracefully.
 345                         if ( preg_match( '/^(?:update|insert|replace|delete)/i', $sql ) ) {
 346                                 wfDebug( "Write query from $fname blocked\n" );
 347                                 return false;
 348                         }
 349                 }
 350
 351                 if ( $wgProfiling ) {
 352                         # generalizeSQL will probably cut down the query to reasonable
 353                         # logging size most of the time. The substr is really just a sanity check.
 354
 355                         # Who's been wasting my precious column space? -- TS
 356                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 357                         $profName = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 358
 359                         wfProfileIn( 'Database::query' );
 360                         wfProfileIn( $profName );
 361                 }
 362
 363                 $this->mLastQuery = $sql;
 364
 365                 # Add a comment for easy SHOW PROCESSLIST interpretation
 366                 if ( $fname ) {
 367                         $commentedSql = "/* $fname */ $sql";
 368                 } else {
 369                         $commentedSql = $sql;
 370                 }
 371
 372                 # If DBO_TRX is set, start a transaction
 373                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 374                         $this->begin();
 375                 }
 376
 377                 if ( $this->debug() ) {
 378                         $sqlx = substr( $commentedSql, 0, 500 );
 379                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 380                         wfDebug( "SQL: $sqlx\n" );
 381                 }
 382
 383                 # Do the query and handle errors
 384                 $ret = $this->doQuery( $commentedSql );
 385
 386                 # Try reconnecting if the connection was lost
 387                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 388                         # Transaction is gone, like it or not
 389                         $this->mTrxLevel = 0;
 390                         wfDebug( "Connection lost, reconnecting...\n" );
 391                         if ( $this->ping() ) {
 392                                 wfDebug( "Reconnected\n" );
 393                                 $ret = $this->doQuery( $commentedSql );
 394                         } else {
 395                                 wfDebug( "Failed\n" );
 396                         }
 397                 }
 398
 399                 if ( false === $ret ) {
 400                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 401                 }
 402
 403                 if ( $wgProfiling ) {
 404                         wfProfileOut( $profName );
 405                         wfProfileOut( 'Database::query' );
 406                 }
 407                 return $ret;
 408         }
 409
 410         /**
 411          * The DBMS-dependent part of query()
 412          * @param string $sql SQL query.
 413          */
 414         function doQuery( $sql ) {
 415                 if( $this->bufferResults() ) {
 416                         $ret = mysql_query( $sql, $this->mConn );
 417                 } else {
 418                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 419                 }
 420                 return $ret;
 421         }
 422
 423         /**
 424          * @param $error
 425          * @param $errno
 426          * @param $sql
 427          * @param string $fname
 428          * @param bool $tempIgnore
 429          */
 430         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 431                 global $wgCommandLineMode, $wgFullyInitialised;
 432                 # Ignore errors during error handling to avoid infinite recursion
 433                 $ignore = $this->ignoreErrors( true );
 434                 ++$this->mErrorCount;
 435
 436                 if( $ignore || $tempIgnore ) {
 437                         wfDebug("SQL ERROR (ignored): $error\n");
 438                 } else {
 439                         $sql1line = str_replace( "\n", "\\n", $sql );
 440                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 441                         wfDebug("SQL ERROR: " . $error . "\n");
 442                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 443                                 $message = "A database error has occurred\n" .
 444                                   "Query: $sql\n" .
 445                                   "Function: $fname\n" .
 446                                   "Error: $errno $error\n";
 447                                 if ( !$wgCommandLineMode ) {
 448                                         $message = nl2br( $message );
 449                                 }
 450                                 wfDebugDieBacktrace( $message );
 451                         } else {
 452                                 // this calls wfAbruptExit()
 453                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 454                         }
 455                 }
 456                 $this->ignoreErrors( $ignore );
 457         }
 458
 459
 460         /**
 461          * Intended to be compatible with the PEAR::DB wrapper functions.
 462          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 463          *
 464          * ? = scalar value, quoted as necessary
 465          * ! = raw SQL bit (a function for instance)
 466          * & = filename; reads the file and inserts as a blob
 467          *     (we don't use this though...)
 468          */
 469         function prepare( $sql, $func = 'Database::prepare' ) {
 470                 /* MySQL doesn't support prepared statements (yet), so just
 471                    pack up the query for reference. We'll manually replace
 472                    the bits later. */
 473                 return array( 'query' => $sql, 'func' => $func );
 474         }
 475
 476         function freePrepared( $prepared ) {
 477                 /* No-op for MySQL */
 478         }
 479
 480         /**
 481          * Execute a prepared query with the various arguments
 482          * @param string $prepared the prepared sql
 483          * @param mixed $args Either an array here, or put scalars as varargs
 484          */
 485         function execute( $prepared, $args = null ) {
 486                 if( !is_array( $args ) ) {
 487                         # Pull the var args
 488                         $args = func_get_args();
 489                         array_shift( $args );
 490                 }
 491                 $sql = $this->fillPrepared( $prepared['query'], $args );
 492                 return $this->query( $sql, $prepared['func'] );
 493         }
 494
 495         /**
 496          * Prepare & execute an SQL statement, quoting and inserting arguments
 497          * in the appropriate places.
 498          * @param string $query
 499          * @param string $args ...
 500          */
 501         function safeQuery( $query, $args = null ) {
 502                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 503                 if( !is_array( $args ) ) {
 504                         # Pull the var args
 505                         $args = func_get_args();
 506                         array_shift( $args );
 507                 }
 508                 $retval = $this->execute( $prepared, $args );
 509                 $this->freePrepared( $prepared );
 510                 return $retval;
 511         }
 512
 513         /**
 514          * For faking prepared SQL statements on DBs that don't support
 515          * it directly.
 516          * @param string $preparedSql - a 'preparable' SQL statement
 517          * @param array $args - array of arguments to fill it with
 518          * @return string executable SQL
 519          */
 520         function fillPrepared( $preparedQuery, $args ) {
 521                 $n = 0;
 522                 reset( $args );
 523                 $this->preparedArgs =& $args;
 524                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 525                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 526         }
 527
 528         /**
 529          * preg_callback func for fillPrepared()
 530          * The arguments should be in $this->preparedArgs and must not be touched
 531          * while we're doing this.
 532          *
 533          * @param array $matches
 534          * @return string
 535          * @access private
 536          */
 537         function fillPreparedArg( $matches ) {
 538                 switch( $matches[1] ) {
 539                         case '\\?': return '?';
 540                         case '\\!': return '!';
 541                         case '\\&': return '&';
 542                 }
 543                 list( $n, $arg ) = each( $this->preparedArgs );
 544                 switch( $matches[1] ) {
 545                         case '?': return $this->addQuotes( $arg );
 546                         case '!': return $arg;
 547                         case '&':
 548                                 # return $this->addQuotes( file_get_contents( $arg ) );
 549                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 550                         default:
 551                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 552                 }
 553         }
 554
 555         /**#@+
 556          * @param mixed $res A SQL result
 557          */
 558         /**
 559          * Free a result object
 560          */
 561         function freeResult( $res ) {
 562                 if ( !@/**/mysql_free_result( $res ) ) {
 563                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 564                 }
 565         }
 566
 567         /**
 568          * Fetch the next row from the given result object, in object form
 569          */
 570         function fetchObject( $res ) {
 571                 @/**/$row = mysql_fetch_object( $res );
 572                 if( mysql_errno() ) {
 573                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 574                 }
 575                 return $row;
 576         }
 577
 578         /**
 579          * Fetch the next row from the given result object
 580          * Returns an array
 581          */
 582         function fetchRow( $res ) {
 583                 @/**/$row = mysql_fetch_array( $res );
 584                 if (mysql_errno() ) {
 585                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 586                 }
 587                 return $row;
 588         }
 589
 590         /**
 591          * Get the number of rows in a result object
 592          */
 593         function numRows( $res ) {
 594                 @/**/$n = mysql_num_rows( $res );
 595                 if( mysql_errno() ) {
 596                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 597                 }
 598                 return $n;
 599         }
 600
 601         /**
 602          * Get the number of fields in a result object
 603          * See documentation for mysql_num_fields()
 604          */
 605         function numFields( $res ) { return mysql_num_fields( $res ); }
 606
 607         /**
 608          * Get a field name in a result object
 609          * See documentation for mysql_field_name()
 610          */
 611         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 612
 613         /**
 614          * Get the inserted value of an auto-increment row
 615          *
 616          * The value inserted should be fetched from nextSequenceValue()
 617          *
 618          * Example:
 619          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 620          * $dbw->insert('page',array('page_id' => $id));
 621          * $id = $dbw->insertId();
 622          */
 623         function insertId() { return mysql_insert_id( $this->mConn ); }
 624
 625         /**
 626          * Change the position of the cursor in a result object
 627          * See mysql_data_seek()
 628          */
 629         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 630
 631         /**
 632          * Get the last error number
 633          * See mysql_errno()
 634          */
 635         function lastErrno() {
 636                 if ( $this->mConn ) {
 637                         return mysql_errno( $this->mConn );
 638                 } else {
 639                         return mysql_errno();
 640                 }
 641         }
 642
 643         /**
 644          * Get a description of the last error
 645          * See mysql_error() for more details
 646          */
 647         function lastError() {
 648                 if ( $this->mConn ) {
 649                         # Even if it's non-zero, it can still be invalid
 650                         wfSuppressWarnings();
 651                         $error = mysql_error( $this->mConn );
 652                         if ( !$error ) {
 653                                 $error = mysql_error();
 654                         }
 655                         wfRestoreWarnings();
 656                 } else {
 657                         $error = mysql_error();
 658                 }
 659                 if( $error ) {
 660                         $error .= ' (' . $this->mServer . ')';
 661                 }
 662                 return $error;
 663         }
 664         /**
 665          * Get the number of rows affected by the last write query
 666          * See mysql_affected_rows() for more details
 667          */
 668         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 669         /**#@-*/ // end of template : @param $result
 670
 671         /**
 672          * Simple UPDATE wrapper
 673          * Usually aborts on failure
 674          * If errors are explicitly ignored, returns success
 675          *
 676          * This function exists for historical reasons, Database::update() has a more standard
 677          * calling convention and feature set
 678          */
 679         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 680         {
 681                 $table = $this->tableName( $table );
 682                 $sql = "UPDATE $table SET $var = '" .
 683                   $this->strencode( $value ) . "' WHERE ($cond)";
 684                 return (bool)$this->query( $sql, DB_MASTER, $fname );
 685         }
 686
 687         /**
 688          * Simple SELECT wrapper, returns a single field, input must be encoded
 689          * Usually aborts on failure
 690          * If errors are explicitly ignored, returns FALSE on failure
 691          */
 692         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 693                 if ( !is_array( $options ) ) {
 694                         $options = array( $options );
 695                 }
 696                 $options['LIMIT'] = 1;
 697
 698                 $res = $this->select( $table, $var, $cond, $fname, $options );
 699                 if ( $res === false || !$this->numRows( $res ) ) {
 700                         return false;
 701                 }
 702                 $row = $this->fetchRow( $res );
 703                 if ( $row !== false ) {
 704                         $this->freeResult( $res );
 705                         return $row[0];
 706                 } else {
 707                         return false;
 708                 }
 709         }
 710
 711         /**
 712          * Returns an optional USE INDEX clause to go after the table, and a
 713          * string to go at the end of the query
 714          *
 715          * @access private
 716          *
 717          * @param array $options an associative array of options to be turned into
 718          *              an SQL query, valid keys are listed in the function.
 719          * @return array
 720          */
 721         function makeSelectOptions( $options ) {
 722                 $tailOpts = '';
 723
 724                 if ( isset( $options['GROUP BY'] ) ) {
 725                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 726                 }
 727                 if ( isset( $options['ORDER BY'] ) ) {
 728                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 729                 }
 730                 if (isset($options['LIMIT'])) {
 731                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 732                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 733                 }
 734                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 735                         $tailOpts .= ' FOR UPDATE';
 736                 }
 737
 738                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 739                         $tailOpts .= ' LOCK IN SHARE MODE';
 740                 }
 741
 742                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 743                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 744                 } else {
 745                         $useIndex = '';
 746                 }
 747                 return array( $useIndex, $tailOpts );
 748         }
 749
 750         /**
 751          * SELECT wrapper
 752          */
 753         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 754         {
 755                 if( is_array( $vars ) ) {
 756                         $vars = implode( ',', $vars );
 757                 }
 758                 if( !is_array( $options ) ) {
 759                         $options = array( $options );
 760                 }
 761                 if( is_array( $table ) ) {
 762                         if ( @is_array( $options['USE INDEX'] ) )
 763                                 $from = ' FROM ' . $this->tableNamesWithUseIndex( $table, $options['USE INDEX'] );
 764                         else
 765                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 766                 } elseif ($table!='') {
 767                         $from = ' FROM ' . $this->tableName( $table );
 768                 } else {
 769                         $from = '';
 770                 }
 771
 772                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 773
 774                 if( !empty( $conds ) ) {
 775                         if ( is_array( $conds ) ) {
 776                                 $conds = $this->makeList( $conds, LIST_AND );
 777                         }
 778                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 779                 } else {
 780                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 781                 }
 782
 783                 return $this->query( $sql, $fname );
 784         }
 785
 786         /**
 787          * Single row SELECT wrapper
 788          * Aborts or returns FALSE on error
 789          *
 790          * $vars: the selected variables
 791          * $conds: a condition map, terms are ANDed together.
 792          *   Items with numeric keys are taken to be literal conditions
 793          * Takes an array of selected variables, and a condition map, which is ANDed
 794          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 795          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 796          * $obj- >page_id is the ID of the Astronomy article
 797          *
 798          * @todo migrate documentation to phpdocumentor format
 799          */
 800         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 801                 $options['LIMIT'] = 1;
 802                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 803                 if ( $res === false )
 804                         return false;
 805                 if ( !$this->numRows($res) ) {
 806                         $this->freeResult($res);
 807                         return false;
 808                 }
 809                 $obj = $this->fetchObject( $res );
 810                 $this->freeResult( $res );
 811                 return $obj;
 812
 813         }
 814
 815         /**
 816          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 817          * It's only slightly flawed. Don't use for anything important.
 818          *
 819          * @param string $sql A SQL Query
 820          * @static
 821          */
 822         function generalizeSQL( $sql ) {
 823                 # This does the same as the regexp below would do, but in such a way
 824                 # as to avoid crashing php on some large strings.
 825                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 826
 827                 $sql = str_replace ( "\\\\", '', $sql);
 828                 $sql = str_replace ( "\\'", '', $sql);
 829                 $sql = str_replace ( "\\\"", '', $sql);
 830                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 831                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 832
 833                 # All newlines, tabs, etc replaced by single space
 834                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 835
 836                 # All numbers => N
 837                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 838
 839                 return $sql;
 840         }
 841
 842         /**
 843          * Determines whether a field exists in a table
 844          * Usually aborts on failure
 845          * If errors are explicitly ignored, returns NULL on failure
 846          */
 847         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 848                 $table = $this->tableName( $table );
 849                 $res = $this->query( 'DESCRIBE '.$table, DB_SLAVE, $fname );
 850                 if ( !$res ) {
 851                         return NULL;
 852                 }
 853
 854                 $found = false;
 855
 856                 while ( $row = $this->fetchObject( $res ) ) {
 857                         if ( $row->Field == $field ) {
 858                                 $found = true;
 859                                 break;
 860                         }
 861                 }
 862                 return $found;
 863         }
 864
 865         /**
 866          * Determines whether an index exists
 867          * Usually aborts on failure
 868          * If errors are explicitly ignored, returns NULL on failure
 869          */
 870         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 871                 $info = $this->indexInfo( $table, $index, $fname );
 872                 if ( is_null( $info ) ) {
 873                         return NULL;
 874                 } else {
 875                         return $info !== false;
 876                 }
 877         }
 878
 879
 880         /**
 881          * Get information about an index into an object
 882          * Returns false if the index does not exist
 883          */
 884         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 885                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 886                 # SHOW INDEX should work for 3.x and up:
 887                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 888                 $table = $this->tableName( $table );
 889                 $sql = 'SHOW INDEX FROM '.$table;
 890                 $res = $this->query( $sql, $fname );
 891                 if ( !$res ) {
 892                         return NULL;
 893                 }
 894
 895                 while ( $row = $this->fetchObject( $res ) ) {
 896                         if ( $row->Key_name == $index ) {
 897                                 return $row;
 898                         }
 899                 }
 900                 return false;
 901         }
 902
 903         /**
 904          * Query whether a given table exists
 905          */
 906         function tableExists( $table ) {
 907                 $table = $this->tableName( $table );
 908                 $old = $this->ignoreErrors( true );
 909                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 910                 $this->ignoreErrors( $old );
 911                 if( $res ) {
 912                         $this->freeResult( $res );
 913                         return true;
 914                 } else {
 915                         return false;
 916                 }
 917         }
 918
 919         /**
 920          * mysql_fetch_field() wrapper
 921          * Returns false if the field doesn't exist
 922          *
 923          * @param $table
 924          * @param $field
 925          */
 926         function fieldInfo( $table, $field ) {
 927                 $table = $this->tableName( $table );
 928                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 929                 $n = mysql_num_fields( $res );
 930                 for( $i = 0; $i < $n; $i++ ) {
 931                         $meta = mysql_fetch_field( $res, $i );
 932                         if( $field == $meta->name ) {
 933                                 return $meta;
 934                         }
 935                 }
 936                 return false;
 937         }
 938
 939         /**
 940          * mysql_field_type() wrapper
 941          */
 942         function fieldType( $res, $index ) {
 943                 return mysql_field_type( $res, $index );
 944         }
 945
 946         /**
 947          * Determines if a given index is unique
 948          */
 949         function indexUnique( $table, $index ) {
 950                 $indexInfo = $this->indexInfo( $table, $index );
 951                 if ( !$indexInfo ) {
 952                         return NULL;
 953                 }
 954                 return !$indexInfo->Non_unique;
 955         }
 956
 957         /**
 958          * INSERT wrapper, inserts an array into a table
 959          *
 960          * $a may be a single associative array, or an array of these with numeric keys, for
 961          * multi-row insert.
 962          *
 963          * Usually aborts on failure
 964          * If errors are explicitly ignored, returns success
 965          */
 966         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 967                 # No rows to insert, easy just return now
 968                 if ( !count( $a ) ) {
 969                         return true;
 970                 }
 971
 972                 $table = $this->tableName( $table );
 973                 if ( !is_array( $options ) ) {
 974                         $options = array( $options );
 975                 }
 976                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
 977                         $multi = true;
 978                         $keys = array_keys( $a[0] );
 979                 } else {
 980                         $multi = false;
 981                         $keys = array_keys( $a );
 982                 }
 983
 984                 $sql = 'INSERT ' . implode( ' ', $options ) .
 985                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 986
 987                 if ( $multi ) {
 988                         $first = true;
 989                         foreach ( $a as $row ) {
 990                                 if ( $first ) {
 991                                         $first = false;
 992                                 } else {
 993                                         $sql .= ',';
 994                                 }
 995                                 $sql .= '(' . $this->makeList( $row ) . ')';
 996                         }
 997                 } else {
 998                         $sql .= '(' . $this->makeList( $a ) . ')';
 999                 }
1000                 return (bool)$this->query( $sql, $fname );
1001         }
1002
1003         /**
1004          * Make UPDATE options for the Database::update function
1005          *
1006          * @access private
1007          * @param array $options The options passed to Database::update
1008          * @return string
1009          */
1010         function makeUpdateOptions( $options ) {
1011                 if( !is_array( $options ) ) {
1012                         $options = array( $options );
1013                 }
1014                 $opts = array();
1015                 if ( in_array( 'LOW_PRIORITY', $options ) )
1016                         $opts[] = $this->lowPriorityOption();
1017                 if ( in_array( 'IGNORE', $options ) )
1018                         $opts[] = 'IGNORE';
1019                 return implode(' ', $opts);
1020         }
1021
1022         /**
1023          * UPDATE wrapper, takes a condition array and a SET array
1024          *
1025          * @param string $table  The table to UPDATE
1026          * @param array  $values An array of values to SET
1027          * @param array  $conds  An array of conditions (WHERE)
1028          * @param string $fname  The Class::Function calling this function
1029          *                       (for the log)
1030          * @param array  $options An array of UPDATE options, can be one or
1031          *                        more of IGNORE, LOW_PRIORITY
1032          */
1033         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1034                 $table = $this->tableName( $table );
1035                 $opts = $this->makeUpdateOptions( $options );
1036                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1037                 if ( $conds != '*' ) {
1038                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1039                 }
1040                 $this->query( $sql, $fname );
1041         }
1042
1043         /**
1044          * Makes a wfStrencoded list from an array
1045          * $mode: LIST_COMMA         - comma separated, no field names
1046          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1047          *        LIST_SET           - comma separated with field names, like a SET clause
1048          *        LIST_NAMES         - comma separated field names
1049          */
1050         function makeList( $a, $mode = LIST_COMMA ) {
1051                 if ( !is_array( $a ) ) {
1052                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1053                 }
1054
1055                 $first = true;
1056                 $list = '';
1057                 foreach ( $a as $field => $value ) {
1058                         if ( !$first ) {
1059                                 if ( $mode == LIST_AND ) {
1060                                         $list .= ' AND ';
1061                                 } elseif($mode == LIST_OR) {
1062                                         $list .= ' OR ';
1063                                 } else {
1064                                         $list .= ',';
1065                                 }
1066                         } else {
1067                                 $first = false;
1068                         }
1069                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1070                                 $list .= "($value)";
1071                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1072                                 $list .= $field." IN (".$this->makeList($value).") ";
1073                         } else {
1074                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1075                                         $list .= "$field = ";
1076                                 }
1077                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1078                         }
1079                 }
1080                 return $list;
1081         }
1082
1083         /**
1084          * Change the current database
1085          */
1086         function selectDB( $db ) {
1087                 $this->mDBname = $db;
1088                 return mysql_select_db( $db, $this->mConn );
1089         }
1090
1091         /**
1092          * Starts a timer which will kill the DB thread after $timeout seconds
1093          */
1094         function startTimer( $timeout ) {
1095                 global $IP;
1096                 if( function_exists( 'mysql_thread_id' ) ) {
1097                         # This will kill the query if it's still running after $timeout seconds.
1098                         $tid = mysql_thread_id( $this->mConn );
1099                         exec( "php $IP/includes/killthread.php $timeout $tid &>/dev/null &" );
1100                 }
1101         }
1102
1103         /**
1104          * Stop a timer started by startTimer()
1105          * Currently unimplemented.
1106          *
1107          */
1108         function stopTimer() { }
1109
1110         /**
1111          * Format a table name ready for use in constructing an SQL query
1112          *
1113          * This does two important things: it quotes table names which as necessary,
1114          * and it adds a table prefix if there is one.
1115          *
1116          * All functions of this object which require a table name call this function
1117          * themselves. Pass the canonical name to such functions. This is only needed
1118          * when calling query() directly.
1119          *
1120          * @param string $name database table name
1121          */
1122         function tableName( $name ) {
1123                 global $wgSharedDB;
1124                 # Skip quoted literals
1125                 if ( $name{0} != '`' ) {
1126                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1127                                 $name = "{$this->mTablePrefix}$name";
1128                         }
1129                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1130                                 $name = "`$wgSharedDB`.`$name`";
1131                         } else {
1132                                 # Standard quoting
1133                                 $name = "`$name`";
1134                         }
1135                 }
1136                 return $name;
1137         }
1138
1139         /**
1140          * Fetch a number of table names into an array
1141          * This is handy when you need to construct SQL for joins
1142          *
1143          * Example:
1144          * extract($dbr->tableNames('user','watchlist'));
1145          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1146          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1147          */
1148         function tableNames() {
1149                 $inArray = func_get_args();
1150                 $retVal = array();
1151                 foreach ( $inArray as $name ) {
1152                         $retVal[$name] = $this->tableName( $name );
1153                 }
1154                 return $retVal;
1155         }
1156
1157         /**
1158          * @access private
1159          */
1160         function tableNamesWithUseIndex( $tables, $use_index ) {
1161                 $ret = array();
1162
1163                 foreach ( $tables as $table )
1164                         if ( @$use_index[$table] !== null )
1165                                 $ret[] = $this->tableName( $table ) . ' ' . $this->useIndexClause( implode( ',', (array)$use_index[$table] ) );
1166                         else
1167                                 $ret[] = $this->tableName( $table );
1168
1169                 return implode( ',', $ret );
1170         }
1171
1172         /**
1173          * Wrapper for addslashes()
1174          * @param string $s String to be slashed.
1175          * @return string slashed string.
1176          */
1177         function strencode( $s ) {
1178                 return addslashes( $s );
1179         }
1180
1181         /**
1182          * If it's a string, adds quotes and backslashes
1183          * Otherwise returns as-is
1184          */
1185         function addQuotes( $s ) {
1186                 if ( is_null( $s ) ) {
1187                         return 'NULL';
1188                 } else {
1189                         # This will also quote numeric values. This should be harmless,
1190                         # and protects against weird problems that occur when they really
1191                         # _are_ strings such as article titles and string->number->string
1192                         # conversion is not 1:1.
1193                         return "'" . $this->strencode( $s ) . "'";
1194                 }
1195         }
1196
1197         /**
1198          * Escape string for safe LIKE usage
1199          */
1200         function escapeLike( $s ) {
1201                 $s=$this->strencode( $s );
1202                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1203                 return $s;
1204         }
1205
1206         /**
1207          * Returns an appropriately quoted sequence value for inserting a new row.
1208          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1209          * subclass will return an integer, and save the value for insertId()
1210          */
1211         function nextSequenceValue( $seqName ) {
1212                 return NULL;
1213         }
1214
1215         /**
1216          * USE INDEX clause
1217          * PostgreSQL doesn't have them and returns ""
1218          */
1219         function useIndexClause( $index ) {
1220                 return "FORCE INDEX ($index)";
1221         }
1222
1223         /**
1224          * REPLACE query wrapper
1225          * PostgreSQL simulates this with a DELETE followed by INSERT
1226          * $row is the row to insert, an associative array
1227          * $uniqueIndexes is an array of indexes. Each element may be either a
1228          * field name or an array of field names
1229          *
1230          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1231          * However if you do this, you run the risk of encountering errors which wouldn't have
1232          * occurred in MySQL
1233          *
1234          * @todo migrate comment to phodocumentor format
1235          */
1236         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1237                 $table = $this->tableName( $table );
1238
1239                 # Single row case
1240                 if ( !is_array( reset( $rows ) ) ) {
1241                         $rows = array( $rows );
1242                 }
1243
1244                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1245                 $first = true;
1246                 foreach ( $rows as $row ) {
1247                         if ( $first ) {
1248                                 $first = false;
1249                         } else {
1250                                 $sql .= ',';
1251                         }
1252                         $sql .= '(' . $this->makeList( $row ) . ')';
1253                 }
1254                 return $this->query( $sql, $fname );
1255         }
1256
1257         /**
1258          * DELETE where the condition is a join
1259          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1260          *
1261          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1262          * join condition matches, set $conds='*'
1263          *
1264          * DO NOT put the join condition in $conds
1265          *
1266          * @param string $delTable The table to delete from.
1267          * @param string $joinTable The other table.
1268          * @param string $delVar The variable to join on, in the first table.
1269          * @param string $joinVar The variable to join on, in the second table.
1270          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1271          */
1272         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1273                 if ( !$conds ) {
1274                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1275                 }
1276
1277                 $delTable = $this->tableName( $delTable );
1278                 $joinTable = $this->tableName( $joinTable );
1279                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1280                 if ( $conds != '*' ) {
1281                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1282                 }
1283
1284                 return $this->query( $sql, $fname );
1285         }
1286
1287         /**
1288          * Returns the size of a text field, or -1 for "unlimited"
1289          */
1290         function textFieldSize( $table, $field ) {
1291                 $table = $this->tableName( $table );
1292                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1293                 $res = $this->query( $sql, 'Database::textFieldSize' );
1294                 $row = $this->fetchObject( $res );
1295                 $this->freeResult( $res );
1296
1297                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1298                         $size = $m[1];
1299                 } else {
1300                         $size = -1;
1301                 }
1302                 return $size;
1303         }
1304
1305         /**
1306          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1307          */
1308         function lowPriorityOption() {
1309                 return 'LOW_PRIORITY';
1310         }
1311
1312         /**
1313          * DELETE query wrapper
1314          *
1315          * Use $conds == "*" to delete all rows
1316          */
1317         function delete( $table, $conds, $fname = 'Database::delete' ) {
1318                 if ( !$conds ) {
1319                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1320                 }
1321                 $table = $this->tableName( $table );
1322                 $sql = "DELETE FROM $table";
1323                 if ( $conds != '*' ) {
1324                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1325                 }
1326                 return $this->query( $sql, $fname );
1327         }
1328
1329         /**
1330          * INSERT SELECT wrapper
1331          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1332          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1333          * $conds may be "*" to copy the whole table
1334          * srcTable may be an array of tables.
1335          */
1336         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect' ) {
1337                 $destTable = $this->tableName( $destTable );
1338                 if( is_array( $srcTable ) ) {
1339                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1340                 } else {
1341                         $srcTable = $this->tableName( $srcTable );
1342                 }
1343                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1344                         ' SELECT ' . implode( ',', $varMap ) .
1345                         " FROM $srcTable";
1346                 if ( $conds != '*' ) {
1347                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1348                 }
1349                 return $this->query( $sql, $fname );
1350         }
1351
1352         /**
1353          * Construct a LIMIT query with optional offset
1354          * This is used for query pages
1355          * $sql string SQL query we will append the limit too
1356          * $limit integer the SQL limit
1357          * $offset integer the SQL offset (default false)
1358          */
1359         function limitResult($sql, $limit, $offset=false) {
1360                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1361         }
1362         function limitResultForUpdate($sql, $num) {
1363                 return $this->limitResult($sql, $num, 0);
1364         }
1365
1366         /**
1367          * Returns an SQL expression for a simple conditional.
1368          * Uses IF on MySQL.
1369          *
1370          * @param string $cond SQL expression which will result in a boolean value
1371          * @param string $trueVal SQL expression to return if true
1372          * @param string $falseVal SQL expression to return if false
1373          * @return string SQL fragment
1374          */
1375         function conditional( $cond, $trueVal, $falseVal ) {
1376                 return " IF($cond, $trueVal, $falseVal) ";
1377         }
1378
1379         /**
1380          * Determines if the last failure was due to a deadlock
1381          */
1382         function wasDeadlock() {
1383                 return $this->lastErrno() == 1213;
1384         }
1385
1386         /**
1387          * Perform a deadlock-prone transaction.
1388          *
1389          * This function invokes a callback function to perform a set of write
1390          * queries. If a deadlock occurs during the processing, the transaction
1391          * will be rolled back and the callback function will be called again.
1392          *
1393          * Usage:
1394          *   $dbw->deadlockLoop( callback, ... );
1395          *
1396          * Extra arguments are passed through to the specified callback function.
1397          *
1398          * Returns whatever the callback function returned on its successful,
1399          * iteration, or false on error, for example if the retry limit was
1400          * reached.
1401          */
1402         function deadlockLoop() {
1403                 $myFname = 'Database::deadlockLoop';
1404
1405                 $this->begin();
1406                 $args = func_get_args();
1407                 $function = array_shift( $args );
1408                 $oldIgnore = $this->ignoreErrors( true );
1409                 $tries = DEADLOCK_TRIES;
1410                 if ( is_array( $function ) ) {
1411                         $fname = $function[0];
1412                 } else {
1413                         $fname = $function;
1414                 }
1415                 do {
1416                         $retVal = call_user_func_array( $function, $args );
1417                         $error = $this->lastError();
1418                         $errno = $this->lastErrno();
1419                         $sql = $this->lastQuery();
1420
1421                         if ( $errno ) {
1422                                 if ( $this->wasDeadlock() ) {
1423                                         # Retry
1424                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1425                                 } else {
1426                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1427                                 }
1428                         }
1429                 } while( $this->wasDeadlock() && --$tries > 0 );
1430                 $this->ignoreErrors( $oldIgnore );
1431                 if ( $tries <= 0 ) {
1432                         $this->query( 'ROLLBACK', $myFname );
1433                         $this->reportQueryError( $error, $errno, $sql, $fname );
1434                         return false;
1435                 } else {
1436                         $this->query( 'COMMIT', $myFname );
1437                         return $retVal;
1438                 }
1439         }
1440
1441         /**
1442          * Do a SELECT MASTER_POS_WAIT()
1443          *
1444          * @param string $file the binlog file
1445          * @param string $pos the binlog position
1446          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1447          */
1448         function masterPosWait( $file, $pos, $timeout ) {
1449                 $fname = 'Database::masterPosWait';
1450                 wfProfileIn( $fname );
1451
1452
1453                 # Commit any open transactions
1454                 $this->immediateCommit();
1455
1456                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1457                 $encFile = $this->strencode( $file );
1458                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1459                 $res = $this->doQuery( $sql );
1460                 if ( $res && $row = $this->fetchRow( $res ) ) {
1461                         $this->freeResult( $res );
1462                         wfProfileOut( $fname );
1463                         return $row[0];
1464                 } else {
1465                         wfProfileOut( $fname );
1466                         return false;
1467                 }
1468         }
1469
1470         /**
1471          * Get the position of the master from SHOW SLAVE STATUS
1472          */
1473         function getSlavePos() {
1474                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1475                 $row = $this->fetchObject( $res );
1476                 if ( $row ) {
1477                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1478                 } else {
1479                         return array( false, false );
1480                 }
1481         }
1482
1483         /**
1484          * Get the position of the master from SHOW MASTER STATUS
1485          */
1486         function getMasterPos() {
1487                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1488                 $row = $this->fetchObject( $res );
1489                 if ( $row ) {
1490                         return array( $row->File, $row->Position );
1491                 } else {
1492                         return array( false, false );
1493                 }
1494         }
1495
1496         /**
1497          * Begin a transaction, or if a transaction has already started, continue it
1498          */
1499         function begin( $fname = 'Database::begin' ) {
1500                 if ( !$this->mTrxLevel ) {
1501                         $this->immediateBegin( $fname );
1502                 } else {
1503                         $this->mTrxLevel++;
1504                 }
1505         }
1506
1507         /**
1508          * End a transaction, or decrement the nest level if transactions are nested
1509          */
1510         function commit( $fname = 'Database::commit' ) {
1511                 if ( $this->mTrxLevel ) {
1512                         $this->mTrxLevel--;
1513                 }
1514                 if ( !$this->mTrxLevel ) {
1515                         $this->immediateCommit( $fname );
1516                 }
1517         }
1518
1519         /**
1520          * Rollback a transaction
1521          */
1522         function rollback( $fname = 'Database::rollback' ) {
1523                 $this->query( 'ROLLBACK', $fname );
1524                 $this->mTrxLevel = 0;
1525         }
1526
1527         /**
1528          * Begin a transaction, committing any previously open transaction
1529          */
1530         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1531                 $this->query( 'BEGIN', $fname );
1532                 $this->mTrxLevel = 1;
1533         }
1534
1535         /**
1536          * Commit transaction, if one is open
1537          */
1538         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1539                 $this->query( 'COMMIT', $fname );
1540                 $this->mTrxLevel = 0;
1541         }
1542
1543         /**
1544          * Return MW-style timestamp used for MySQL schema
1545          */
1546         function timestamp( $ts=0 ) {
1547                 return wfTimestamp(TS_MW,$ts);
1548         }
1549
1550         /**
1551          * Local database timestamp format or null
1552          */
1553         function timestampOrNull( $ts = null ) {
1554                 if( is_null( $ts ) ) {
1555                         return null;
1556                 } else {
1557                         return $this->timestamp( $ts );
1558                 }
1559         }
1560
1561         /**
1562          * @todo document
1563          */
1564         function resultObject( $result ) {
1565                 if( empty( $result ) ) {
1566                         return NULL;
1567                 } else {
1568                         return new ResultWrapper( $this, $result );
1569                 }
1570         }
1571
1572         /**
1573          * Return aggregated value alias
1574          */
1575         function aggregateValue ($valuedata,$valuename='value') {
1576                 return $valuename;
1577         }
1578
1579         /**
1580          * @return string wikitext of a link to the server software's web site
1581          */
1582         function getSoftwareLink() {
1583                 return "[http://www.mysql.com/ MySQL]";
1584         }
1585
1586         /**
1587          * @return string Version information from the database
1588          */
1589         function getServerVersion() {
1590                 return mysql_get_server_info();
1591         }
1592
1593         /**
1594          * Ping the server and try to reconnect if it there is no connection
1595          */
1596         function ping() {
1597                 if( function_exists( 'mysql_ping' ) ) {
1598                         return mysql_ping( $this->mConn );
1599                 } else {
1600                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1601                         return true;
1602                 }
1603         }
1604
1605         /**
1606          * Get slave lag.
1607          * At the moment, this will only work if the DB user has the PROCESS privilege
1608          */
1609         function getLag() {
1610                 $res = $this->query( 'SHOW PROCESSLIST' );
1611                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1612                 # dubious, but unfortunately there's no easy rigorous way
1613                 $slaveThreads = 0;
1614                 while ( $row = $this->fetchObject( $res ) ) {
1615                         if ( $row->User == 'system user' ) {
1616                                 if ( ++$slaveThreads == 2 ) {
1617                                         # This is it, return the time
1618                                         return $row->Time;
1619                                 }
1620                         }
1621                 }
1622                 return false;
1623         }
1624
1625         /**
1626          * Get status information from SHOW STATUS in an associative array
1627          */
1628         function getStatus() {
1629                 $res = $this->query( 'SHOW STATUS' );
1630                 $status = array();
1631                 while ( $row = $this->fetchObject( $res ) ) {
1632                         $status[$row->Variable_name] = $row->Value;
1633                 }
1634                 return $status;
1635         }
1636
1637         /**
1638          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1639          */
1640         function maxListLen() {
1641                 return 0;
1642         }
1643
1644         function encodeBlob($b) {
1645                 return $b;
1646         }
1647
1648         function notNullTimestamp() {
1649                 return "!= 0";
1650         }
1651         function isNullTimestamp() {
1652                 return "= '0'";
1653         }
1654 }
1655
1656 /**
1657  * Database abstraction object for mySQL
1658  * Inherit all methods and properties of Database::Database()
1659  *
1660  * @package MediaWiki
1661  * @see Database
1662  */
1663 class DatabaseMysql extends Database {
1664         # Inherit all
1665 }
1666
1667
1668 /**
1669  * Result wrapper for grabbing data queried by someone else
1670  *
1671  * @package MediaWiki
1672  */
1673 class ResultWrapper {
1674         var $db, $result;
1675
1676         /**
1677          * @todo document
1678          */
1679         function ResultWrapper( $database, $result ) {
1680                 $this->db =& $database;
1681                 $this->result =& $result;
1682         }
1683
1684         /**
1685          * @todo document
1686          */
1687         function numRows() {
1688                 return $this->db->numRows( $this->result );
1689         }
1690
1691         /**
1692          * @todo document
1693          */
1694         function fetchObject() {
1695                 return $this->db->fetchObject( $this->result );
1696         }
1697
1698         /**
1699          * @todo document
1700          */
1701         function &fetchRow() {
1702                 return $this->db->fetchRow( $this->result );
1703         }
1704
1705         /**
1706          * @todo document
1707          */
1708         function free() {
1709                 $this->db->freeResult( $this->result );
1710                 unset( $this->result );
1711                 unset( $this->db );
1712         }
1713
1714         function seek( $row ) {
1715                 $this->db->dataSeek( $this->result, $row );
1716         }
1717 }
1718
1719 #------------------------------------------------------------------------------
1720 # Global functions
1721 #------------------------------------------------------------------------------
1722
1723 /**
1724  * Standard fail function, called by default when a connection cannot be
1725  * established.
1726  * Displays the file cache if possible
1727  */
1728 function wfEmergencyAbort( &$conn, $error ) {
1729         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1730         global $wgSitename, $wgServer, $wgMessageCache, $wgLogo;
1731
1732         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1733         # Hard coding strings instead.
1734
1735         $noconnect = "<h1><img src='$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>";
1736         $mainpage = 'Main Page';
1737         $searchdisabled = <<<EOT
1738 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1739 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1740 EOT;
1741
1742         $googlesearch = "
1743 <!-- SiteSearch Google -->
1744 <FORM method=GET action=\"http://www.google.com/search\">
1745 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1746 <A HREF=\"http://www.google.com/\">
1747 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1748 border=\"0\" ALT=\"Google\"></A>
1749 </td>
1750 <td>
1751 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1752 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1753 <font size=-1>
1754 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1755 <input type='hidden' name='ie' value='$2'>
1756 <input type='hidden' name='oe' value='$2'>
1757 </font>
1758 </td></tr></TABLE>
1759 </FORM>
1760 <!-- SiteSearch Google -->";
1761         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1762
1763
1764         if( !headers_sent() ) {
1765                 header( 'HTTP/1.0 500 Internal Server Error' );
1766                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1767                 /* Don't cache error pages!  They cause no end of trouble... */
1768                 header( 'Cache-control: none' );
1769                 header( 'Pragma: nocache' );
1770         }
1771
1772         # No database access
1773         if ( is_object( $wgMessageCache ) ) {
1774                 $wgMessageCache->disable();
1775         }
1776
1777         if ( trim( $error ) == '' ) {
1778                 $error = $this->mServer;
1779         }
1780
1781         wfLogDBError( "Connection error: $error\n" );
1782
1783         $msg = wfGetSiteNotice();
1784         if($msg == '') {
1785                 $msg = str_replace( '$1', $error, $noconnect );
1786         }
1787         $text = $msg;
1788
1789         if($wgUseFileCache) {
1790                 if($wgTitle) {
1791                         $t =& $wgTitle;
1792                 } else {
1793                         if($title) {
1794                                 $t = Title::newFromURL( $title );
1795                         } elseif (@/**/$_REQUEST['search']) {
1796                                 $search = $_REQUEST['search'];
1797                                 echo $searchdisabled;
1798                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1799                                   $wgInputEncoding ), $googlesearch );
1800                                 wfErrorExit();
1801                         } else {
1802                                 $t = Title::newFromText( $mainpage );
1803                         }
1804                 }
1805
1806                 $cache = new CacheManager( $t );
1807                 if( $cache->isFileCached() ) {
1808                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1809                                 $cachederror . "</b></p>\n";
1810
1811                         $tag = '<div id="article">';
1812                         $text = str_replace(
1813                                 $tag,
1814                                 $tag . $msg,
1815                                 $cache->fetchPageText() );
1816                 }
1817         }
1818
1819         echo $text;
1820         wfErrorExit();
1821 }
1822
1823 ?>