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         var $mLBInfo = array();
  66         /**#@-*/
  67
  68 #------------------------------------------------------------------------------
  69 # Accessors
  70 #------------------------------------------------------------------------------
  71         # These optionally set a variable and return the previous state
  72
  73         /**
  74          * Fail function, takes a Database as a parameter
  75          * Set to false for default, 1 for ignore errors
  76          */
  77         function failFunction( $function = NULL ) {
  78                 return wfSetVar( $this->mFailFunction, $function );
  79         }
  80
  81         /**
  82          * Output page, used for reporting errors
  83          * FALSE means discard output
  84          */
  85         function &setOutputPage( &$out ) {
  86                 $this->mOut =& $out;
  87         }
  88
  89         /**
  90          * Boolean, controls output of large amounts of debug information
  91          */
  92         function debug( $debug = NULL ) {
  93                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
  94         }
  95
  96         /**
  97          * Turns buffering of SQL result sets on (true) or off (false).
  98          * Default is "on" and it should not be changed without good reasons.
  99          */
 100         function bufferResults( $buffer = NULL ) {
 101                 if ( is_null( $buffer ) ) {
 102                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 103                 } else {
 104                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 105                 }
 106         }
 107
 108         /**
 109          * Turns on (false) or off (true) the automatic generation and sending
 110          * of a "we're sorry, but there has been a database error" page on
 111          * database errors. Default is on (false). When turned off, the
 112          * code should use wfLastErrno() and wfLastError() to handle the
 113          * situation as appropriate.
 114          */
 115         function ignoreErrors( $ignoreErrors = NULL ) {
 116                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 117         }
 118
 119         /**
 120          * The current depth of nested transactions
 121          * @param integer $level
 122          */
 123         function trxLevel( $level = NULL ) {
 124                 return wfSetVar( $this->mTrxLevel, $level );
 125         }
 126
 127         /**
 128          * Number of errors logged, only useful when errors are ignored
 129          */
 130         function errorCount( $count = NULL ) {
 131                 return wfSetVar( $this->mErrorCount, $count );
 132         }
 133
 134         /**
 135          * Properties passed down from the server info array of the load balancer
 136          */
 137         function getLBInfo( $name = NULL ) {
 138                 if ( is_null( $name ) ) {
 139                         return $this->mLBInfo;
 140                 } else {
 141                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 142                                 return $this->mLBInfo[$name];
 143                         } else {
 144                                 return NULL;
 145                         }
 146                 }
 147         }
 148
 149         function setLBInfo( $name, $value = NULL ) {
 150                 if ( is_null( $value ) ) {
 151                         $this->mLBInfo = $name;
 152                 } else {
 153                         $this->mLBInfo[$name] = $value;
 154                 }
 155         }
 156
 157         /**#@+
 158          * Get function
 159          */
 160         function lastQuery() { return $this->mLastQuery; }
 161         function isOpen() { return $this->mOpened; }
 162         /**#@-*/
 163
 164         function setFlag( $flag ) {
 165                 $this->mFlags |= $flag;
 166         }
 167
 168         function clearFlag( $flag ) {
 169                 $this->mFlags &= ~$flag;
 170         }
 171
 172         function getFlag( $flag ) {
 173                 return !!($this->mFlags & $flag);
 174         }
 175
 176 #------------------------------------------------------------------------------
 177 # Other functions
 178 #------------------------------------------------------------------------------
 179
 180         /**#@+
 181          * @param string $server database server host
 182          * @param string $user database user name
 183          * @param string $password database user password
 184          * @param string $dbname database name
 185          */
 186
 187         /**
 188          * @param failFunction
 189          * @param $flags
 190          * @param string $tablePrefix Database table prefixes. By default use the prefix gave in LocalSettings.php
 191          */
 192         function Database( $server = false, $user = false, $password = false, $dbName = false,
 193                 $failFunction = false, $flags = 0, $tablePrefix = 'get from global' ) {
 194
 195                 global $wgOut, $wgDBprefix, $wgCommandLineMode;
 196                 # Can't get a reference if it hasn't been set yet
 197                 if ( !isset( $wgOut ) ) {
 198                         $wgOut = NULL;
 199                 }
 200                 $this->mOut =& $wgOut;
 201
 202                 $this->mFailFunction = $failFunction;
 203                 $this->mFlags = $flags;
 204
 205                 if ( $this->mFlags & DBO_DEFAULT ) {
 206                         if ( $wgCommandLineMode ) {
 207                                 $this->mFlags &= ~DBO_TRX;
 208                         } else {
 209                                 $this->mFlags |= DBO_TRX;
 210                         }
 211                 }
 212
 213                 /*
 214                 // Faster read-only access
 215                 if ( wfReadOnly() ) {
 216                         $this->mFlags |= DBO_PERSISTENT;
 217                         $this->mFlags &= ~DBO_TRX;
 218                 }*/
 219
 220                 /** Get the default table prefix*/
 221                 if ( $tablePrefix == 'get from global' ) {
 222                         $this->mTablePrefix = $wgDBprefix;
 223                 } else {
 224                         $this->mTablePrefix = $tablePrefix;
 225                 }
 226
 227                 if ( $server ) {
 228                         $this->open( $server, $user, $password, $dbName );
 229                 }
 230         }
 231
 232         /**
 233          * @static
 234          * @param failFunction
 235          * @param $flags
 236          */
 237         function newFromParams( $server, $user, $password, $dbName,
 238                 $failFunction = false, $flags = 0 )
 239         {
 240                 return new Database( $server, $user, $password, $dbName, $failFunction, $flags );
 241         }
 242
 243         /**
 244          * Usually aborts on failure
 245          * If the failFunction is set to a non-zero integer, returns success
 246          */
 247         function open( $server, $user, $password, $dbName ) {
 248                 global $wguname;
 249
 250                 # Test for missing mysql.so
 251                 # First try to load it
 252                 if (!@extension_loaded('mysql')) {
 253                         @dl('mysql.so');
 254                 }
 255
 256                 # Otherwise we get a suppressed fatal error, which is very hard to track down
 257                 if ( !function_exists( 'mysql_connect' ) ) {
 258                         wfDie( "MySQL functions missing, have you compiled PHP with the --with-mysql option?\n" );
 259                 }
 260
 261                 $this->close();
 262                 $this->mServer = $server;
 263                 $this->mUser = $user;
 264                 $this->mPassword = $password;
 265                 $this->mDBname = $dbName;
 266
 267                 $success = false;
 268
 269                 if ( $this->mFlags & DBO_PERSISTENT ) {
 270                         @/**/$this->mConn = mysql_pconnect( $server, $user, $password );
 271                 } else {
 272                         # Create a new connection...
 273                         if( version_compare( PHP_VERSION, '4.2.0', 'ge' ) ) {
 274                                 @/**/$this->mConn = mysql_connect( $server, $user, $password, true );
 275                         } else {
 276                                 # On PHP 4.1 the new_link parameter is not available. We cannot
 277                                 # guarantee that we'll actually get a new connection, and this
 278                                 # may cause some operations to fail possibly.
 279                                 @/**/$this->mConn = mysql_connect( $server, $user, $password );
 280                         }
 281                 }
 282
 283                 if ( $dbName != '' ) {
 284                         if ( $this->mConn !== false ) {
 285                                 $success = @/**/mysql_select_db( $dbName, $this->mConn );
 286                                 if ( !$success ) {
 287                                         $error = "Error selecting database $dbName on server {$this->mServer} " .
 288                                                 "from client host {$wguname['nodename']}\n";
 289                                         wfDebug( $error );
 290                                 }
 291                         } else {
 292                                 wfDebug( "DB connection error\n" );
 293                                 wfDebug( "Server: $server, User: $user, Password: " .
 294                                         substr( $password, 0, 3 ) . "..., error: " . mysql_error() . "\n" );
 295                                 $success = false;
 296                         }
 297                 } else {
 298                         # Delay USE query
 299                         $success = (bool)$this->mConn;
 300                 }
 301
 302                 if ( !$success ) {
 303                         $this->reportConnectionError();
 304                 }
 305
 306                 global $wgDBmysql5;
 307                 if( $wgDBmysql5 ) {
 308                         // Tell the server we're communicating with it in UTF-8.
 309                         // This may engage various charset conversions.
 310                         $this->query( 'SET NAMES utf8' );
 311                 }
 312
 313                 $this->mOpened = $success;
 314                 return $success;
 315         }
 316         /**#@-*/
 317
 318         /**
 319          * Closes a database connection.
 320          * if it is open : commits any open transactions
 321          *
 322          * @return bool operation success. true if already closed.
 323          */
 324         function close()
 325         {
 326                 $this->mOpened = false;
 327                 if ( $this->mConn ) {
 328                         if ( $this->trxLevel() ) {
 329                                 $this->immediateCommit();
 330                         }
 331                         return mysql_close( $this->mConn );
 332                 } else {
 333                         return true;
 334                 }
 335         }
 336
 337         /**
 338          * @access private
 339          * @param string $error fallback error message, used if none is given by MySQL
 340          */
 341         function reportConnectionError( $error = 'Unknown error' ) {
 342                 $myError = $this->lastError();
 343                 if ( $myError ) {
 344                         $error = $myError;
 345                 }
 346
 347                 if ( $this->mFailFunction ) {
 348                         if ( !is_int( $this->mFailFunction ) ) {
 349                                 $ff = $this->mFailFunction;
 350                                 $ff( $this, $error );
 351                         }
 352                 } else {
 353                         wfEmergencyAbort( $this, $error );
 354                 }
 355         }
 356
 357         /**
 358          * Usually aborts on failure
 359          * If errors are explicitly ignored, returns success
 360          */
 361         function query( $sql, $fname = '', $tempIgnore = false ) {
 362                 global $wgProfiling, $wgCommandLineMode;
 363
 364                 if ( $wgProfiling ) {
 365                         # generalizeSQL will probably cut down the query to reasonable
 366                         # logging size most of the time. The substr is really just a sanity check.
 367
 368                         # Who's been wasting my precious column space? -- TS
 369                         #$profName = 'query: ' . $fname . ' ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 370                         $profName = 'query: ' . substr( Database::generalizeSQL( $sql ), 0, 255 );
 371
 372                         wfProfileIn( 'Database::query' );
 373                         wfProfileIn( $profName );
 374                 }
 375
 376                 $this->mLastQuery = $sql;
 377
 378                 # Add a comment for easy SHOW PROCESSLIST interpretation
 379                 if ( $fname ) {
 380                         $commentedSql = preg_replace("/\s/", " /* $fname */ ", $sql, 1);
 381                 } else {
 382                         $commentedSql = $sql;
 383                 }
 384
 385                 # If DBO_TRX is set, start a transaction
 386                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() && $sql != 'BEGIN' ) {
 387                         $this->begin();
 388                 }
 389
 390                 if ( $this->debug() ) {
 391                         $sqlx = substr( $commentedSql, 0, 500 );
 392                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 393                         wfDebug( "SQL: $sqlx\n" );
 394                 }
 395
 396                 # Do the query and handle errors
 397                 $ret = $this->doQuery( $commentedSql );
 398
 399                 # Try reconnecting if the connection was lost
 400                 if ( false === $ret && ( $this->lastErrno() == 2013 || $this->lastErrno() == 2006 ) ) {
 401                         # Transaction is gone, like it or not
 402                         $this->mTrxLevel = 0;
 403                         wfDebug( "Connection lost, reconnecting...\n" );
 404                         if ( $this->ping() ) {
 405                                 wfDebug( "Reconnected\n" );
 406                                 $ret = $this->doQuery( $commentedSql );
 407                         } else {
 408                                 wfDebug( "Failed\n" );
 409                         }
 410                 }
 411
 412                 if ( false === $ret ) {
 413                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 414                 }
 415
 416                 if ( $wgProfiling ) {
 417                         wfProfileOut( $profName );
 418                         wfProfileOut( 'Database::query' );
 419                 }
 420                 return $ret;
 421         }
 422
 423         /**
 424          * The DBMS-dependent part of query()
 425          * @param string $sql SQL query.
 426          */
 427         function doQuery( $sql ) {
 428                 if( $this->bufferResults() ) {
 429                         $ret = mysql_query( $sql, $this->mConn );
 430                 } else {
 431                         $ret = mysql_unbuffered_query( $sql, $this->mConn );
 432                 }
 433                 return $ret;
 434         }
 435
 436         /**
 437          * @param $error
 438          * @param $errno
 439          * @param $sql
 440          * @param string $fname
 441          * @param bool $tempIgnore
 442          */
 443         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 444                 global $wgCommandLineMode, $wgFullyInitialised;
 445                 # Ignore errors during error handling to avoid infinite recursion
 446                 $ignore = $this->ignoreErrors( true );
 447                 ++$this->mErrorCount;
 448
 449                 if( $ignore || $tempIgnore ) {
 450                         wfDebug("SQL ERROR (ignored): $error\n");
 451                 } else {
 452                         $sql1line = str_replace( "\n", "\\n", $sql );
 453                         wfLogDBError("$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n");
 454                         wfDebug("SQL ERROR: " . $error . "\n");
 455                         if ( $wgCommandLineMode || !$this->mOut || empty( $wgFullyInitialised ) ) {
 456                                 $message = "A database error has occurred\n" .
 457                                   "Query: $sql\n" .
 458                                   "Function: $fname\n" .
 459                                   "Error: $errno $error\n";
 460                                 if ( !$wgCommandLineMode ) {
 461                                         $message = nl2br( $message );
 462                                 }
 463                                 wfDebugDieBacktrace( $message );
 464                         } else {
 465                                 // this calls wfAbruptExit()
 466                                 $this->mOut->databaseError( $fname, $sql, $error, $errno );
 467                         }
 468                 }
 469                 $this->ignoreErrors( $ignore );
 470         }
 471
 472
 473         /**
 474          * Intended to be compatible with the PEAR::DB wrapper functions.
 475          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 476          *
 477          * ? = scalar value, quoted as necessary
 478          * ! = raw SQL bit (a function for instance)
 479          * & = filename; reads the file and inserts as a blob
 480          *     (we don't use this though...)
 481          */
 482         function prepare( $sql, $func = 'Database::prepare' ) {
 483                 /* MySQL doesn't support prepared statements (yet), so just
 484                    pack up the query for reference. We'll manually replace
 485                    the bits later. */
 486                 return array( 'query' => $sql, 'func' => $func );
 487         }
 488
 489         function freePrepared( $prepared ) {
 490                 /* No-op for MySQL */
 491         }
 492
 493         /**
 494          * Execute a prepared query with the various arguments
 495          * @param string $prepared the prepared sql
 496          * @param mixed $args Either an array here, or put scalars as varargs
 497          */
 498         function execute( $prepared, $args = null ) {
 499                 if( !is_array( $args ) ) {
 500                         # Pull the var args
 501                         $args = func_get_args();
 502                         array_shift( $args );
 503                 }
 504                 $sql = $this->fillPrepared( $prepared['query'], $args );
 505                 return $this->query( $sql, $prepared['func'] );
 506         }
 507
 508         /**
 509          * Prepare & execute an SQL statement, quoting and inserting arguments
 510          * in the appropriate places.
 511          * @param string $query
 512          * @param string $args ...
 513          */
 514         function safeQuery( $query, $args = null ) {
 515                 $prepared = $this->prepare( $query, 'Database::safeQuery' );
 516                 if( !is_array( $args ) ) {
 517                         # Pull the var args
 518                         $args = func_get_args();
 519                         array_shift( $args );
 520                 }
 521                 $retval = $this->execute( $prepared, $args );
 522                 $this->freePrepared( $prepared );
 523                 return $retval;
 524         }
 525
 526         /**
 527          * For faking prepared SQL statements on DBs that don't support
 528          * it directly.
 529          * @param string $preparedSql - a 'preparable' SQL statement
 530          * @param array $args - array of arguments to fill it with
 531          * @return string executable SQL
 532          */
 533         function fillPrepared( $preparedQuery, $args ) {
 534                 $n = 0;
 535                 reset( $args );
 536                 $this->preparedArgs =& $args;
 537                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 538                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 539         }
 540
 541         /**
 542          * preg_callback func for fillPrepared()
 543          * The arguments should be in $this->preparedArgs and must not be touched
 544          * while we're doing this.
 545          *
 546          * @param array $matches
 547          * @return string
 548          * @access private
 549          */
 550         function fillPreparedArg( $matches ) {
 551                 switch( $matches[1] ) {
 552                         case '\\?': return '?';
 553                         case '\\!': return '!';
 554                         case '\\&': return '&';
 555                 }
 556                 list( $n, $arg ) = each( $this->preparedArgs );
 557                 switch( $matches[1] ) {
 558                         case '?': return $this->addQuotes( $arg );
 559                         case '!': return $arg;
 560                         case '&':
 561                                 # return $this->addQuotes( file_get_contents( $arg ) );
 562                                 wfDebugDieBacktrace( '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 563                         default:
 564                                 wfDebugDieBacktrace( 'Received invalid match. This should never happen!' );
 565                 }
 566         }
 567
 568         /**#@+
 569          * @param mixed $res A SQL result
 570          */
 571         /**
 572          * Free a result object
 573          */
 574         function freeResult( $res ) {
 575                 if ( !@/**/mysql_free_result( $res ) ) {
 576                         wfDebugDieBacktrace( "Unable to free MySQL result\n" );
 577                 }
 578         }
 579
 580         /**
 581          * Fetch the next row from the given result object, in object form
 582          */
 583         function fetchObject( $res ) {
 584                 @/**/$row = mysql_fetch_object( $res );
 585                 if( mysql_errno() ) {
 586                         wfDebugDieBacktrace( 'Error in fetchObject(): ' . htmlspecialchars( mysql_error() ) );
 587                 }
 588                 return $row;
 589         }
 590
 591         /**
 592          * Fetch the next row from the given result object
 593          * Returns an array
 594          */
 595         function fetchRow( $res ) {
 596                 @/**/$row = mysql_fetch_array( $res );
 597                 if (mysql_errno() ) {
 598                         wfDebugDieBacktrace( 'Error in fetchRow(): ' . htmlspecialchars( mysql_error() ) );
 599                 }
 600                 return $row;
 601         }
 602
 603         /**
 604          * Get the number of rows in a result object
 605          */
 606         function numRows( $res ) {
 607                 @/**/$n = mysql_num_rows( $res );
 608                 if( mysql_errno() ) {
 609                         wfDebugDieBacktrace( 'Error in numRows(): ' . htmlspecialchars( mysql_error() ) );
 610                 }
 611                 return $n;
 612         }
 613
 614         /**
 615          * Get the number of fields in a result object
 616          * See documentation for mysql_num_fields()
 617          */
 618         function numFields( $res ) { return mysql_num_fields( $res ); }
 619
 620         /**
 621          * Get a field name in a result object
 622          * See documentation for mysql_field_name()
 623          */
 624         function fieldName( $res, $n ) { return mysql_field_name( $res, $n ); }
 625
 626         /**
 627          * Get the inserted value of an auto-increment row
 628          *
 629          * The value inserted should be fetched from nextSequenceValue()
 630          *
 631          * Example:
 632          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 633          * $dbw->insert('page',array('page_id' => $id));
 634          * $id = $dbw->insertId();
 635          */
 636         function insertId() { return mysql_insert_id( $this->mConn ); }
 637
 638         /**
 639          * Change the position of the cursor in a result object
 640          * See mysql_data_seek()
 641          */
 642         function dataSeek( $res, $row ) { return mysql_data_seek( $res, $row ); }
 643
 644         /**
 645          * Get the last error number
 646          * See mysql_errno()
 647          */
 648         function lastErrno() {
 649                 if ( $this->mConn ) {
 650                         return mysql_errno( $this->mConn );
 651                 } else {
 652                         return mysql_errno();
 653                 }
 654         }
 655
 656         /**
 657          * Get a description of the last error
 658          * See mysql_error() for more details
 659          */
 660         function lastError() {
 661                 if ( $this->mConn ) {
 662                         # Even if it's non-zero, it can still be invalid
 663                         wfSuppressWarnings();
 664                         $error = mysql_error( $this->mConn );
 665                         if ( !$error ) {
 666                                 $error = mysql_error();
 667                         }
 668                         wfRestoreWarnings();
 669                 } else {
 670                         $error = mysql_error();
 671                 }
 672                 if( $error ) {
 673                         $error .= ' (' . $this->mServer . ')';
 674                 }
 675                 return $error;
 676         }
 677         /**
 678          * Get the number of rows affected by the last write query
 679          * See mysql_affected_rows() for more details
 680          */
 681         function affectedRows() { return mysql_affected_rows( $this->mConn ); }
 682         /**#@-*/ // end of template : @param $result
 683
 684         /**
 685          * Simple UPDATE wrapper
 686          * Usually aborts on failure
 687          * If errors are explicitly ignored, returns success
 688          *
 689          * This function exists for historical reasons, Database::update() has a more standard
 690          * calling convention and feature set
 691          */
 692         function set( $table, $var, $value, $cond, $fname = 'Database::set' )
 693         {
 694                 $table = $this->tableName( $table );
 695                 $sql = "UPDATE $table SET $var = '" .
 696                   $this->strencode( $value ) . "' WHERE ($cond)";
 697                 return (bool)$this->query( $sql, $fname );
 698         }
 699
 700         /**
 701          * Simple SELECT wrapper, returns a single field, input must be encoded
 702          * Usually aborts on failure
 703          * If errors are explicitly ignored, returns FALSE on failure
 704          */
 705         function selectField( $table, $var, $cond='', $fname = 'Database::selectField', $options = array() ) {
 706                 if ( !is_array( $options ) ) {
 707                         $options = array( $options );
 708                 }
 709                 $options['LIMIT'] = 1;
 710
 711                 $res = $this->select( $table, $var, $cond, $fname, $options );
 712                 if ( $res === false || !$this->numRows( $res ) ) {
 713                         return false;
 714                 }
 715                 $row = $this->fetchRow( $res );
 716                 if ( $row !== false ) {
 717                         $this->freeResult( $res );
 718                         return $row[0];
 719                 } else {
 720                         return false;
 721                 }
 722         }
 723
 724         /**
 725          * Returns an optional USE INDEX clause to go after the table, and a
 726          * string to go at the end of the query
 727          *
 728          * @access private
 729          *
 730          * @param array $options an associative array of options to be turned into
 731          *              an SQL query, valid keys are listed in the function.
 732          * @return array
 733          */
 734         function makeSelectOptions( $options ) {
 735                 $tailOpts = '';
 736
 737                 if ( isset( $options['GROUP BY'] ) ) {
 738                         $tailOpts .= " GROUP BY {$options['GROUP BY']}";
 739                 }
 740                 if ( isset( $options['ORDER BY'] ) ) {
 741                         $tailOpts .= " ORDER BY {$options['ORDER BY']}";
 742                 }
 743                 if (isset($options['LIMIT'])) {
 744                         $tailOpts .= $this->limitResult('', $options['LIMIT'],
 745                                 isset($options['OFFSET']) ? $options['OFFSET'] : false);
 746                 }
 747                 if ( is_numeric( array_search( 'FOR UPDATE', $options ) ) ) {
 748                         $tailOpts .= ' FOR UPDATE';
 749                 }
 750
 751                 if ( is_numeric( array_search( 'LOCK IN SHARE MODE', $options ) ) ) {
 752                         $tailOpts .= ' LOCK IN SHARE MODE';
 753                 }
 754
 755                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
 756                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
 757                 } else {
 758                         $useIndex = '';
 759                 }
 760                 return array( $useIndex, $tailOpts );
 761         }
 762
 763         /**
 764          * SELECT wrapper
 765          */
 766         function select( $table, $vars, $conds='', $fname = 'Database::select', $options = array() )
 767         {
 768                 if( is_array( $vars ) ) {
 769                         $vars = implode( ',', $vars );
 770                 }
 771                 if( !is_array( $options ) ) {
 772                         $options = array( $options );
 773                 }
 774                 if( is_array( $table ) ) {
 775                         if ( @is_array( $options['USE INDEX'] ) )
 776                                 $from = ' FROM ' . $this->tableNamesWithUseIndex( $table, $options['USE INDEX'] );
 777                         else
 778                                 $from = ' FROM ' . implode( ',', array_map( array( &$this, 'tableName' ), $table ) );
 779                 } elseif ($table!='') {
 780                         $from = ' FROM ' . $this->tableName( $table );
 781                 } else {
 782                         $from = '';
 783                 }
 784
 785                 list( $useIndex, $tailOpts ) = $this->makeSelectOptions( $options );
 786
 787                 if( !empty( $conds ) ) {
 788                         if ( is_array( $conds ) ) {
 789                                 $conds = $this->makeList( $conds, LIST_AND );
 790                         }
 791                         $sql = "SELECT $vars $from $useIndex WHERE $conds $tailOpts";
 792                 } else {
 793                         $sql = "SELECT $vars $from $useIndex $tailOpts";
 794                 }
 795
 796                 return $this->query( $sql, $fname );
 797         }
 798
 799         /**
 800          * Single row SELECT wrapper
 801          * Aborts or returns FALSE on error
 802          *
 803          * $vars: the selected variables
 804          * $conds: a condition map, terms are ANDed together.
 805          *   Items with numeric keys are taken to be literal conditions
 806          * Takes an array of selected variables, and a condition map, which is ANDed
 807          * e.g: selectRow( "page", array( "page_id" ), array( "page_namespace" =>
 808          * NS_MAIN, "page_title" => "Astronomy" ) )   would return an object where
 809          * $obj- >page_id is the ID of the Astronomy article
 810          *
 811          * @todo migrate documentation to phpdocumentor format
 812          */
 813         function selectRow( $table, $vars, $conds, $fname = 'Database::selectRow', $options = array() ) {
 814                 $options['LIMIT'] = 1;
 815                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 816                 if ( $res === false )
 817                         return false;
 818                 if ( !$this->numRows($res) ) {
 819                         $this->freeResult($res);
 820                         return false;
 821                 }
 822                 $obj = $this->fetchObject( $res );
 823                 $this->freeResult( $res );
 824                 return $obj;
 825
 826         }
 827
 828         /**
 829          * Removes most variables from an SQL query and replaces them with X or N for numbers.
 830          * It's only slightly flawed. Don't use for anything important.
 831          *
 832          * @param string $sql A SQL Query
 833          * @static
 834          */
 835         function generalizeSQL( $sql ) {
 836                 # This does the same as the regexp below would do, but in such a way
 837                 # as to avoid crashing php on some large strings.
 838                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
 839
 840                 $sql = str_replace ( "\\\\", '', $sql);
 841                 $sql = str_replace ( "\\'", '', $sql);
 842                 $sql = str_replace ( "\\\"", '', $sql);
 843                 $sql = preg_replace ("/'.*'/s", "'X'", $sql);
 844                 $sql = preg_replace ('/".*"/s', "'X'", $sql);
 845
 846                 # All newlines, tabs, etc replaced by single space
 847                 $sql = preg_replace ( "/\s+/", ' ', $sql);
 848
 849                 # All numbers => N
 850                 $sql = preg_replace ('/-?[0-9]+/s', 'N', $sql);
 851
 852                 return $sql;
 853         }
 854
 855         /**
 856          * Determines whether a field exists in a table
 857          * Usually aborts on failure
 858          * If errors are explicitly ignored, returns NULL on failure
 859          */
 860         function fieldExists( $table, $field, $fname = 'Database::fieldExists' ) {
 861                 $table = $this->tableName( $table );
 862                 $res = $this->query( 'DESCRIBE '.$table, $fname );
 863                 if ( !$res ) {
 864                         return NULL;
 865                 }
 866
 867                 $found = false;
 868
 869                 while ( $row = $this->fetchObject( $res ) ) {
 870                         if ( $row->Field == $field ) {
 871                                 $found = true;
 872                                 break;
 873                         }
 874                 }
 875                 return $found;
 876         }
 877
 878         /**
 879          * Determines whether an index exists
 880          * Usually aborts on failure
 881          * If errors are explicitly ignored, returns NULL on failure
 882          */
 883         function indexExists( $table, $index, $fname = 'Database::indexExists' ) {
 884                 $info = $this->indexInfo( $table, $index, $fname );
 885                 if ( is_null( $info ) ) {
 886                         return NULL;
 887                 } else {
 888                         return $info !== false;
 889                 }
 890         }
 891
 892
 893         /**
 894          * Get information about an index into an object
 895          * Returns false if the index does not exist
 896          */
 897         function indexInfo( $table, $index, $fname = 'Database::indexInfo' ) {
 898                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 899                 # SHOW INDEX should work for 3.x and up:
 900                 # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 901                 $table = $this->tableName( $table );
 902                 $sql = 'SHOW INDEX FROM '.$table;
 903                 $res = $this->query( $sql, $fname );
 904                 if ( !$res ) {
 905                         return NULL;
 906                 }
 907
 908                 while ( $row = $this->fetchObject( $res ) ) {
 909                         if ( $row->Key_name == $index ) {
 910                                 return $row;
 911                         }
 912                 }
 913                 return false;
 914         }
 915
 916         /**
 917          * Query whether a given table exists
 918          */
 919         function tableExists( $table ) {
 920                 $table = $this->tableName( $table );
 921                 $old = $this->ignoreErrors( true );
 922                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1" );
 923                 $this->ignoreErrors( $old );
 924                 if( $res ) {
 925                         $this->freeResult( $res );
 926                         return true;
 927                 } else {
 928                         return false;
 929                 }
 930         }
 931
 932         /**
 933          * mysql_fetch_field() wrapper
 934          * Returns false if the field doesn't exist
 935          *
 936          * @param $table
 937          * @param $field
 938          */
 939         function fieldInfo( $table, $field ) {
 940                 $table = $this->tableName( $table );
 941                 $res = $this->query( "SELECT * FROM $table LIMIT 1" );
 942                 $n = mysql_num_fields( $res );
 943                 for( $i = 0; $i < $n; $i++ ) {
 944                         $meta = mysql_fetch_field( $res, $i );
 945                         if( $field == $meta->name ) {
 946                                 return $meta;
 947                         }
 948                 }
 949                 return false;
 950         }
 951
 952         /**
 953          * mysql_field_type() wrapper
 954          */
 955         function fieldType( $res, $index ) {
 956                 return mysql_field_type( $res, $index );
 957         }
 958
 959         /**
 960          * Determines if a given index is unique
 961          */
 962         function indexUnique( $table, $index ) {
 963                 $indexInfo = $this->indexInfo( $table, $index );
 964                 if ( !$indexInfo ) {
 965                         return NULL;
 966                 }
 967                 return !$indexInfo->Non_unique;
 968         }
 969
 970         /**
 971          * INSERT wrapper, inserts an array into a table
 972          *
 973          * $a may be a single associative array, or an array of these with numeric keys, for
 974          * multi-row insert.
 975          *
 976          * Usually aborts on failure
 977          * If errors are explicitly ignored, returns success
 978          */
 979         function insert( $table, $a, $fname = 'Database::insert', $options = array() ) {
 980                 # No rows to insert, easy just return now
 981                 if ( !count( $a ) ) {
 982                         return true;
 983                 }
 984
 985                 $table = $this->tableName( $table );
 986                 if ( !is_array( $options ) ) {
 987                         $options = array( $options );
 988                 }
 989                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
 990                         $multi = true;
 991                         $keys = array_keys( $a[0] );
 992                 } else {
 993                         $multi = false;
 994                         $keys = array_keys( $a );
 995                 }
 996
 997                 $sql = 'INSERT ' . implode( ' ', $options ) .
 998                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 999
1000                 if ( $multi ) {
1001                         $first = true;
1002                         foreach ( $a as $row ) {
1003                                 if ( $first ) {
1004                                         $first = false;
1005                                 } else {
1006                                         $sql .= ',';
1007                                 }
1008                                 $sql .= '(' . $this->makeList( $row ) . ')';
1009                         }
1010                 } else {
1011                         $sql .= '(' . $this->makeList( $a ) . ')';
1012                 }
1013                 return (bool)$this->query( $sql, $fname );
1014         }
1015
1016         /**
1017          * Make UPDATE options for the Database::update function
1018          *
1019          * @access private
1020          * @param array $options The options passed to Database::update
1021          * @return string
1022          */
1023         function makeUpdateOptions( $options ) {
1024                 if( !is_array( $options ) ) {
1025                         $options = array( $options );
1026                 }
1027                 $opts = array();
1028                 if ( in_array( 'LOW_PRIORITY', $options ) )
1029                         $opts[] = $this->lowPriorityOption();
1030                 if ( in_array( 'IGNORE', $options ) )
1031                         $opts[] = 'IGNORE';
1032                 return implode(' ', $opts);
1033         }
1034
1035         /**
1036          * UPDATE wrapper, takes a condition array and a SET array
1037          *
1038          * @param string $table  The table to UPDATE
1039          * @param array  $values An array of values to SET
1040          * @param array  $conds  An array of conditions (WHERE)
1041          * @param string $fname  The Class::Function calling this function
1042          *                       (for the log)
1043          * @param array  $options An array of UPDATE options, can be one or
1044          *                        more of IGNORE, LOW_PRIORITY
1045          */
1046         function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1047                 $table = $this->tableName( $table );
1048                 $opts = $this->makeUpdateOptions( $options );
1049                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1050                 if ( $conds != '*' ) {
1051                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1052                 }
1053                 $this->query( $sql, $fname );
1054         }
1055
1056         /**
1057          * Makes a wfStrencoded list from an array
1058          * $mode: LIST_COMMA         - comma separated, no field names
1059          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
1060          *        LIST_SET           - comma separated with field names, like a SET clause
1061          *        LIST_NAMES         - comma separated field names
1062          */
1063         function makeList( $a, $mode = LIST_COMMA ) {
1064                 if ( !is_array( $a ) ) {
1065                         wfDebugDieBacktrace( 'Database::makeList called with incorrect parameters' );
1066                 }
1067
1068                 $first = true;
1069                 $list = '';
1070                 foreach ( $a as $field => $value ) {
1071                         if ( !$first ) {
1072                                 if ( $mode == LIST_AND ) {
1073                                         $list .= ' AND ';
1074                                 } elseif($mode == LIST_OR) {
1075                                         $list .= ' OR ';
1076                                 } else {
1077                                         $list .= ',';
1078                                 }
1079                         } else {
1080                                 $first = false;
1081                         }
1082                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
1083                                 $list .= "($value)";
1084                         } elseif ( $mode == LIST_AND && is_array ($value) ) {
1085                                 $list .= $field." IN (".$this->makeList($value).") ";
1086                         } else {
1087                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1088                                         $list .= "$field = ";
1089                                 }
1090                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1091                         }
1092                 }
1093                 return $list;
1094         }
1095
1096         /**
1097          * Change the current database
1098          */
1099         function selectDB( $db ) {
1100                 $this->mDBname = $db;
1101                 return mysql_select_db( $db, $this->mConn );
1102         }
1103
1104         /**
1105          * Format a table name ready for use in constructing an SQL query
1106          *
1107          * This does two important things: it quotes table names which as necessary,
1108          * and it adds a table prefix if there is one.
1109          *
1110          * All functions of this object which require a table name call this function
1111          * themselves. Pass the canonical name to such functions. This is only needed
1112          * when calling query() directly.
1113          *
1114          * @param string $name database table name
1115          */
1116         function tableName( $name ) {
1117                 global $wgSharedDB;
1118                 # Skip quoted literals
1119                 if ( $name{0} != '`' ) {
1120                         if ( $this->mTablePrefix !== '' &&  strpos( '.', $name ) === false ) {
1121                                 $name = "{$this->mTablePrefix}$name";
1122                         }
1123                         if ( isset( $wgSharedDB ) && "{$this->mTablePrefix}user" == $name ) {
1124                                 $name = "`$wgSharedDB`.`$name`";
1125                         } else {
1126                                 # Standard quoting
1127                                 $name = "`$name`";
1128                         }
1129                 }
1130                 return $name;
1131         }
1132
1133         /**
1134          * Fetch a number of table names into an array
1135          * This is handy when you need to construct SQL for joins
1136          *
1137          * Example:
1138          * extract($dbr->tableNames('user','watchlist'));
1139          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1140          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1141          */
1142         function tableNames() {
1143                 $inArray = func_get_args();
1144                 $retVal = array();
1145                 foreach ( $inArray as $name ) {
1146                         $retVal[$name] = $this->tableName( $name );
1147                 }
1148                 return $retVal;
1149         }
1150
1151         /**
1152          * @access private
1153          */
1154         function tableNamesWithUseIndex( $tables, $use_index ) {
1155                 $ret = array();
1156
1157                 foreach ( $tables as $table )
1158                         if ( @$use_index[$table] !== null )
1159                                 $ret[] = $this->tableName( $table ) . ' ' . $this->useIndexClause( implode( ',', (array)$use_index[$table] ) );
1160                         else
1161                                 $ret[] = $this->tableName( $table );
1162
1163                 return implode( ',', $ret );
1164         }
1165
1166         /**
1167          * Wrapper for addslashes()
1168          * @param string $s String to be slashed.
1169          * @return string slashed string.
1170          */
1171         function strencode( $s ) {
1172                 return addslashes( $s );
1173         }
1174
1175         /**
1176          * If it's a string, adds quotes and backslashes
1177          * Otherwise returns as-is
1178          */
1179         function addQuotes( $s ) {
1180                 if ( is_null( $s ) ) {
1181                         return 'NULL';
1182                 } else {
1183                         # This will also quote numeric values. This should be harmless,
1184                         # and protects against weird problems that occur when they really
1185                         # _are_ strings such as article titles and string->number->string
1186                         # conversion is not 1:1.
1187                         return "'" . $this->strencode( $s ) . "'";
1188                 }
1189         }
1190
1191         /**
1192          * Escape string for safe LIKE usage
1193          */
1194         function escapeLike( $s ) {
1195                 $s=$this->strencode( $s );
1196                 $s=str_replace(array('%','_'),array('\%','\_'),$s);
1197                 return $s;
1198         }
1199
1200         /**
1201          * Returns an appropriately quoted sequence value for inserting a new row.
1202          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1203          * subclass will return an integer, and save the value for insertId()
1204          */
1205         function nextSequenceValue( $seqName ) {
1206                 return NULL;
1207         }
1208
1209         /**
1210          * USE INDEX clause
1211          * PostgreSQL doesn't have them and returns ""
1212          */
1213         function useIndexClause( $index ) {
1214                 return "FORCE INDEX ($index)";
1215         }
1216
1217         /**
1218          * REPLACE query wrapper
1219          * PostgreSQL simulates this with a DELETE followed by INSERT
1220          * $row is the row to insert, an associative array
1221          * $uniqueIndexes is an array of indexes. Each element may be either a
1222          * field name or an array of field names
1223          *
1224          * It may be more efficient to leave off unique indexes which are unlikely to collide.
1225          * However if you do this, you run the risk of encountering errors which wouldn't have
1226          * occurred in MySQL
1227          *
1228          * @todo migrate comment to phodocumentor format
1229          */
1230         function replace( $table, $uniqueIndexes, $rows, $fname = 'Database::replace' ) {
1231                 $table = $this->tableName( $table );
1232
1233                 # Single row case
1234                 if ( !is_array( reset( $rows ) ) ) {
1235                         $rows = array( $rows );
1236                 }
1237
1238                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) .') VALUES ';
1239                 $first = true;
1240                 foreach ( $rows as $row ) {
1241                         if ( $first ) {
1242                                 $first = false;
1243                         } else {
1244                                 $sql .= ',';
1245                         }
1246                         $sql .= '(' . $this->makeList( $row ) . ')';
1247                 }
1248                 return $this->query( $sql, $fname );
1249         }
1250
1251         /**
1252          * DELETE where the condition is a join
1253          * MySQL does this with a multi-table DELETE syntax, PostgreSQL does it with sub-selects
1254          *
1255          * For safety, an empty $conds will not delete everything. If you want to delete all rows where the
1256          * join condition matches, set $conds='*'
1257          *
1258          * DO NOT put the join condition in $conds
1259          *
1260          * @param string $delTable The table to delete from.
1261          * @param string $joinTable The other table.
1262          * @param string $delVar The variable to join on, in the first table.
1263          * @param string $joinVar The variable to join on, in the second table.
1264          * @param array $conds Condition array of field names mapped to variables, ANDed together in the WHERE clause
1265          */
1266         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'Database::deleteJoin' ) {
1267                 if ( !$conds ) {
1268                         wfDebugDieBacktrace( 'Database::deleteJoin() called with empty $conds' );
1269                 }
1270
1271                 $delTable = $this->tableName( $delTable );
1272                 $joinTable = $this->tableName( $joinTable );
1273                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1274                 if ( $conds != '*' ) {
1275                         $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
1276                 }
1277
1278                 return $this->query( $sql, $fname );
1279         }
1280
1281         /**
1282          * Returns the size of a text field, or -1 for "unlimited"
1283          */
1284         function textFieldSize( $table, $field ) {
1285                 $table = $this->tableName( $table );
1286                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
1287                 $res = $this->query( $sql, 'Database::textFieldSize' );
1288                 $row = $this->fetchObject( $res );
1289                 $this->freeResult( $res );
1290
1291                 if ( preg_match( "/\((.*)\)/", $row->Type, $m ) ) {
1292                         $size = $m[1];
1293                 } else {
1294                         $size = -1;
1295                 }
1296                 return $size;
1297         }
1298
1299         /**
1300          * @return string Returns the text of the low priority option if it is supported, or a blank string otherwise
1301          */
1302         function lowPriorityOption() {
1303                 return 'LOW_PRIORITY';
1304         }
1305
1306         /**
1307          * DELETE query wrapper
1308          *
1309          * Use $conds == "*" to delete all rows
1310          */
1311         function delete( $table, $conds, $fname = 'Database::delete' ) {
1312                 if ( !$conds ) {
1313                         wfDebugDieBacktrace( 'Database::delete() called with no conditions' );
1314                 }
1315                 $table = $this->tableName( $table );
1316                 $sql = "DELETE FROM $table";
1317                 if ( $conds != '*' ) {
1318                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1319                 }
1320                 return $this->query( $sql, $fname );
1321         }
1322
1323         /**
1324          * INSERT SELECT wrapper
1325          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
1326          * Source items may be literals rather than field names, but strings should be quoted with Database::addQuotes()
1327          * $conds may be "*" to copy the whole table
1328          * srcTable may be an array of tables.
1329          */
1330         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'Database::insertSelect' ) {
1331                 $destTable = $this->tableName( $destTable );
1332                 if( is_array( $srcTable ) ) {
1333                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
1334                 } else {
1335                         $srcTable = $this->tableName( $srcTable );
1336                 }
1337                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
1338                         ' SELECT ' . implode( ',', $varMap ) .
1339                         " FROM $srcTable";
1340                 if ( $conds != '*' ) {
1341                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1342                 }
1343                 return $this->query( $sql, $fname );
1344         }
1345
1346         /**
1347          * Construct a LIMIT query with optional offset
1348          * This is used for query pages
1349          * $sql string SQL query we will append the limit too
1350          * $limit integer the SQL limit
1351          * $offset integer the SQL offset (default false)
1352          */
1353         function limitResult($sql, $limit, $offset=false) {
1354                 return " $sql LIMIT ".((is_numeric($offset) && $offset != 0)?"{$offset},":"")."{$limit} ";
1355         }
1356         function limitResultForUpdate($sql, $num) {
1357                 return $this->limitResult($sql, $num, 0);
1358         }
1359
1360         /**
1361          * Returns an SQL expression for a simple conditional.
1362          * Uses IF on MySQL.
1363          *
1364          * @param string $cond SQL expression which will result in a boolean value
1365          * @param string $trueVal SQL expression to return if true
1366          * @param string $falseVal SQL expression to return if false
1367          * @return string SQL fragment
1368          */
1369         function conditional( $cond, $trueVal, $falseVal ) {
1370                 return " IF($cond, $trueVal, $falseVal) ";
1371         }
1372
1373         /**
1374          * Determines if the last failure was due to a deadlock
1375          */
1376         function wasDeadlock() {
1377                 return $this->lastErrno() == 1213;
1378         }
1379
1380         /**
1381          * Perform a deadlock-prone transaction.
1382          *
1383          * This function invokes a callback function to perform a set of write
1384          * queries. If a deadlock occurs during the processing, the transaction
1385          * will be rolled back and the callback function will be called again.
1386          *
1387          * Usage:
1388          *   $dbw->deadlockLoop( callback, ... );
1389          *
1390          * Extra arguments are passed through to the specified callback function.
1391          *
1392          * Returns whatever the callback function returned on its successful,
1393          * iteration, or false on error, for example if the retry limit was
1394          * reached.
1395          */
1396         function deadlockLoop() {
1397                 $myFname = 'Database::deadlockLoop';
1398
1399                 $this->begin();
1400                 $args = func_get_args();
1401                 $function = array_shift( $args );
1402                 $oldIgnore = $this->ignoreErrors( true );
1403                 $tries = DEADLOCK_TRIES;
1404                 if ( is_array( $function ) ) {
1405                         $fname = $function[0];
1406                 } else {
1407                         $fname = $function;
1408                 }
1409                 do {
1410                         $retVal = call_user_func_array( $function, $args );
1411                         $error = $this->lastError();
1412                         $errno = $this->lastErrno();
1413                         $sql = $this->lastQuery();
1414
1415                         if ( $errno ) {
1416                                 if ( $this->wasDeadlock() ) {
1417                                         # Retry
1418                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
1419                                 } else {
1420                                         $this->reportQueryError( $error, $errno, $sql, $fname );
1421                                 }
1422                         }
1423                 } while( $this->wasDeadlock() && --$tries > 0 );
1424                 $this->ignoreErrors( $oldIgnore );
1425                 if ( $tries <= 0 ) {
1426                         $this->query( 'ROLLBACK', $myFname );
1427                         $this->reportQueryError( $error, $errno, $sql, $fname );
1428                         return false;
1429                 } else {
1430                         $this->query( 'COMMIT', $myFname );
1431                         return $retVal;
1432                 }
1433         }
1434
1435         /**
1436          * Do a SELECT MASTER_POS_WAIT()
1437          *
1438          * @param string $file the binlog file
1439          * @param string $pos the binlog position
1440          * @param integer $timeout the maximum number of seconds to wait for synchronisation
1441          */
1442         function masterPosWait( $file, $pos, $timeout ) {
1443                 $fname = 'Database::masterPosWait';
1444                 wfProfileIn( $fname );
1445
1446
1447                 # Commit any open transactions
1448                 $this->immediateCommit();
1449
1450                 # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
1451                 $encFile = $this->strencode( $file );
1452                 $sql = "SELECT MASTER_POS_WAIT('$encFile', $pos, $timeout)";
1453                 $res = $this->doQuery( $sql );
1454                 if ( $res && $row = $this->fetchRow( $res ) ) {
1455                         $this->freeResult( $res );
1456                         wfProfileOut( $fname );
1457                         return $row[0];
1458                 } else {
1459                         wfProfileOut( $fname );
1460                         return false;
1461                 }
1462         }
1463
1464         /**
1465          * Get the position of the master from SHOW SLAVE STATUS
1466          */
1467         function getSlavePos() {
1468                 $res = $this->query( 'SHOW SLAVE STATUS', 'Database::getSlavePos' );
1469                 $row = $this->fetchObject( $res );
1470                 if ( $row ) {
1471                         return array( $row->Master_Log_File, $row->Read_Master_Log_Pos );
1472                 } else {
1473                         return array( false, false );
1474                 }
1475         }
1476
1477         /**
1478          * Get the position of the master from SHOW MASTER STATUS
1479          */
1480         function getMasterPos() {
1481                 $res = $this->query( 'SHOW MASTER STATUS', 'Database::getMasterPos' );
1482                 $row = $this->fetchObject( $res );
1483                 if ( $row ) {
1484                         return array( $row->File, $row->Position );
1485                 } else {
1486                         return array( false, false );
1487                 }
1488         }
1489
1490         /**
1491          * Begin a transaction, or if a transaction has already started, continue it
1492          */
1493         function begin( $fname = 'Database::begin' ) {
1494                 if ( !$this->mTrxLevel ) {
1495                         $this->immediateBegin( $fname );
1496                 } else {
1497                         $this->mTrxLevel++;
1498                 }
1499         }
1500
1501         /**
1502          * End a transaction, or decrement the nest level if transactions are nested
1503          */
1504         function commit( $fname = 'Database::commit' ) {
1505                 if ( $this->mTrxLevel ) {
1506                         $this->mTrxLevel--;
1507                 }
1508                 if ( !$this->mTrxLevel ) {
1509                         $this->immediateCommit( $fname );
1510                 }
1511         }
1512
1513         /**
1514          * Rollback a transaction
1515          */
1516         function rollback( $fname = 'Database::rollback' ) {
1517                 $this->query( 'ROLLBACK', $fname );
1518                 $this->mTrxLevel = 0;
1519         }
1520
1521         /**
1522          * Begin a transaction, committing any previously open transaction
1523          */
1524         function immediateBegin( $fname = 'Database::immediateBegin' ) {
1525                 $this->query( 'BEGIN', $fname );
1526                 $this->mTrxLevel = 1;
1527         }
1528
1529         /**
1530          * Commit transaction, if one is open
1531          */
1532         function immediateCommit( $fname = 'Database::immediateCommit' ) {
1533                 $this->query( 'COMMIT', $fname );
1534                 $this->mTrxLevel = 0;
1535         }
1536
1537         /**
1538          * Return MW-style timestamp used for MySQL schema
1539          */
1540         function timestamp( $ts=0 ) {
1541                 return wfTimestamp(TS_MW,$ts);
1542         }
1543
1544         /**
1545          * Local database timestamp format or null
1546          */
1547         function timestampOrNull( $ts = null ) {
1548                 if( is_null( $ts ) ) {
1549                         return null;
1550                 } else {
1551                         return $this->timestamp( $ts );
1552                 }
1553         }
1554
1555         /**
1556          * @todo document
1557          */
1558         function resultObject( $result ) {
1559                 if( empty( $result ) ) {
1560                         return NULL;
1561                 } else {
1562                         return new ResultWrapper( $this, $result );
1563                 }
1564         }
1565
1566         /**
1567          * Return aggregated value alias
1568          */
1569         function aggregateValue ($valuedata,$valuename='value') {
1570                 return $valuename;
1571         }
1572
1573         /**
1574          * @return string wikitext of a link to the server software's web site
1575          */
1576         function getSoftwareLink() {
1577                 return "[http://www.mysql.com/ MySQL]";
1578         }
1579
1580         /**
1581          * @return string Version information from the database
1582          */
1583         function getServerVersion() {
1584                 return mysql_get_server_info();
1585         }
1586
1587         /**
1588          * Ping the server and try to reconnect if it there is no connection
1589          */
1590         function ping() {
1591                 if( function_exists( 'mysql_ping' ) ) {
1592                         return mysql_ping( $this->mConn );
1593                 } else {
1594                         wfDebug( "Tried to call mysql_ping but this is ancient PHP version. Faking it!\n" );
1595                         return true;
1596                 }
1597         }
1598
1599         /**
1600          * Get slave lag.
1601          * At the moment, this will only work if the DB user has the PROCESS privilege
1602          */
1603         function getLag() {
1604                 $res = $this->query( 'SHOW PROCESSLIST' );
1605                 # Find slave SQL thread. Assumed to be the second one running, which is a bit
1606                 # dubious, but unfortunately there's no easy rigorous way
1607                 $slaveThreads = 0;
1608                 while ( $row = $this->fetchObject( $res ) ) {
1609                         if ( $row->User == 'system user' ) {
1610                                 if ( ++$slaveThreads == 2 ) {
1611                                         # This is it, return the time (except -ve)
1612                                         if ( $row->Time > 1>>31 ) {
1613                                                 return 0;
1614                                         } else {
1615                                                 return $row->Time;
1616                                         }
1617                                 }
1618                         }
1619                 }
1620                 return false;
1621         }
1622
1623         /**
1624          * Get status information from SHOW STATUS in an associative array
1625          */
1626         function getStatus($which="%") {
1627                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1628                 $status = array();
1629                 while ( $row = $this->fetchObject( $res ) ) {
1630                         $status[$row->Variable_name] = $row->Value;
1631                 }
1632                 return $status;
1633         }
1634
1635         /**
1636          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1637          */
1638         function maxListLen() {
1639                 return 0;
1640         }
1641
1642         function encodeBlob($b) {
1643                 return $b;
1644         }
1645
1646         /**
1647          * Read and execute SQL commands from a file.
1648          * Returns true on success, error string on failure
1649          */
1650         function sourceFile( $filename ) {
1651                 $fp = fopen( $filename, 'r' );
1652                 if ( false === $fp ) {
1653                         return "Could not open \"{$fname}\".\n";
1654                 }
1655
1656                 $cmd = "";
1657                 $done = false;
1658
1659                 while ( ! feof( $fp ) ) {
1660                         $line = trim( fgets( $fp, 1024 ) );
1661                         $sl = strlen( $line ) - 1;
1662
1663                         if ( $sl < 0 ) { continue; }
1664                         if ( '-' == $line{0} && '-' == $line{1} ) { continue; }
1665
1666                         if ( ';' == $line{$sl} && ($sl < 2 || ';' != $line{$sl - 1})) {
1667                                 $done = true;
1668                                 $line = substr( $line, 0, $sl );
1669                         }
1670
1671                         if ( '' != $cmd ) { $cmd .= ' '; }
1672                         $cmd .= "$line\n";
1673
1674                         if ( $done ) {
1675                                 $cmd = str_replace(';;', ";", $cmd);
1676                                 $cmd = $this->replaceVars( $cmd );
1677                                 $res = $this->query( $cmd, 'dbsource', true );
1678
1679                                 if ( false === $res ) {
1680                                         $err = $this->lastError();
1681                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
1682                                 }
1683
1684                                 $cmd = '';
1685                                 $done = false;
1686                         }
1687                 }
1688                 fclose( $fp );
1689                 return true;
1690         }
1691
1692         /**
1693          * Replace variables in sourced SQL
1694          */
1695         function replaceVars( $ins ) {
1696                 $varnames = array(
1697                         'wgDBserver', 'wgDBname', 'wgDBintlname', 'wgDBuser',
1698                         'wgDBpassword', 'wgDBsqluser', 'wgDBsqlpassword',
1699                         'wgDBadminuser', 'wgDBadminpassword',
1700                 );
1701
1702                 // Ordinary variables
1703                 foreach ( $varnames as $var ) {
1704                         if( isset( $GLOBALS[$var] ) ) {
1705                                 $val = addslashes( $GLOBALS[$var] );
1706                                 $ins = str_replace( '{$' . $var . '}', $val, $ins );
1707                                 $ins = str_replace( '/*$' . $var . '*/`', '`' . $val, $ins );
1708                                 $ins = str_replace( '/*$' . $var . '*/', $val, $ins );
1709                         }
1710                 }
1711
1712                 // Table prefixes
1713                 $ins = preg_replace_callback( '/\/\*(?:\$wgDBprefix|_)\*\/([a-z_]*)/',
1714                         array( &$this, 'tableNameCallback' ), $ins );
1715                 return $ins;
1716         }
1717
1718         /**
1719          * Table name callback
1720          * @access private
1721          */
1722         function tableNameCallback( $matches ) {
1723                 return $this->tableName( $matches[1] );
1724         }
1725
1726 }
1727
1728 /**
1729  * Database abstraction object for mySQL
1730  * Inherit all methods and properties of Database::Database()
1731  *
1732  * @package MediaWiki
1733  * @see Database
1734  */
1735 class DatabaseMysql extends Database {
1736         # Inherit all
1737 }
1738
1739
1740 /**
1741  * Result wrapper for grabbing data queried by someone else
1742  *
1743  * @package MediaWiki
1744  */
1745 class ResultWrapper {
1746         var $db, $result;
1747
1748         /**
1749          * @todo document
1750          */
1751         function ResultWrapper( &$database, $result ) {
1752                 $this->db =& $database;
1753                 $this->result =& $result;
1754         }
1755
1756         /**
1757          * @todo document
1758          */
1759         function numRows() {
1760                 return $this->db->numRows( $this->result );
1761         }
1762
1763         /**
1764          * @todo document
1765          */
1766         function fetchObject() {
1767                 return $this->db->fetchObject( $this->result );
1768         }
1769
1770         /**
1771          * @todo document
1772          */
1773         function &fetchRow() {
1774                 return $this->db->fetchRow( $this->result );
1775         }
1776
1777         /**
1778          * @todo document
1779          */
1780         function free() {
1781                 $this->db->freeResult( $this->result );
1782                 unset( $this->result );
1783                 unset( $this->db );
1784         }
1785
1786         function seek( $row ) {
1787                 $this->db->dataSeek( $this->result, $row );
1788         }
1789
1790 }
1791
1792
1793 #------------------------------------------------------------------------------
1794 # Global functions
1795 #------------------------------------------------------------------------------
1796
1797 /**
1798  * Standard fail function, called by default when a connection cannot be
1799  * established.
1800  * Displays the file cache if possible
1801  */
1802 function wfEmergencyAbort( &$conn, $error ) {
1803         global $wgTitle, $wgUseFileCache, $title, $wgInputEncoding, $wgOutputEncoding;
1804         global $wgSitename, $wgServer, $wgMessageCache, $wgLogo;
1805
1806         # I give up, Brion is right. Getting the message cache to work when there is no DB is tricky.
1807         # Hard coding strings instead.
1808
1809         $noconnect = "<h1><img src='$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>";
1810         $mainpage = 'Main Page';
1811         $searchdisabled = <<<EOT
1812 <p style="margin: 1.5em 2em 1em">$wgSitename search is disabled for performance reasons. You can search via Google in the meantime.
1813 <span style="font-size: 89%; display: block; margin-left: .2em">Note that their indexes of $wgSitename content may be out of date.</span></p>',
1814 EOT;
1815
1816         $googlesearch = "
1817 <!-- SiteSearch Google -->
1818 <FORM method=GET action=\"http://www.google.com/search\">
1819 <TABLE bgcolor=\"#FFFFFF\"><tr><td>
1820 <A HREF=\"http://www.google.com/\">
1821 <IMG SRC=\"http://www.google.com/logos/Logo_40wht.gif\"
1822 border=\"0\" ALT=\"Google\"></A>
1823 </td>
1824 <td>
1825 <INPUT TYPE=text name=q size=31 maxlength=255 value=\"$1\">
1826 <INPUT type=submit name=btnG VALUE=\"Google Search\">
1827 <font size=-1>
1828 <input type=hidden name=domains value=\"$wgServer\"><br /><input type=radio name=sitesearch value=\"\"> WWW <input type=radio name=sitesearch value=\"$wgServer\" checked> $wgServer <br />
1829 <input type='hidden' name='ie' value='$2'>
1830 <input type='hidden' name='oe' value='$2'>
1831 </font>
1832 </td></tr></TABLE>
1833 </FORM>
1834 <!-- SiteSearch Google -->";
1835         $cachederror = "The following is a cached copy of the requested page, and may not be up to date. ";
1836
1837
1838         if( !headers_sent() ) {
1839                 header( 'HTTP/1.0 500 Internal Server Error' );
1840                 header( 'Content-type: text/html; charset='.$wgOutputEncoding );
1841                 /* Don't cache error pages!  They cause no end of trouble... */
1842                 header( 'Cache-control: none' );
1843                 header( 'Pragma: nocache' );
1844         }
1845
1846         # No database access
1847         if ( is_object( $wgMessageCache ) ) {
1848                 $wgMessageCache->disable();
1849         }
1850
1851         if ( trim( $error ) == '' ) {
1852                 $error = $this->mServer;
1853         }
1854
1855         wfLogDBError( "Connection error: $error\n" );
1856
1857         $text = str_replace( '$1', $error, $noconnect );
1858         $text .= wfGetSiteNotice();
1859
1860         if($wgUseFileCache) {
1861                 if($wgTitle) {
1862                         $t =& $wgTitle;
1863                 } else {
1864                         if($title) {
1865                                 $t = Title::newFromURL( $title );
1866                         } elseif (@/**/$_REQUEST['search']) {
1867                                 $search = $_REQUEST['search'];
1868                                 echo $searchdisabled;
1869                                 echo str_replace( array( '$1', '$2' ), array( htmlspecialchars( $search ),
1870                                   $wgInputEncoding ), $googlesearch );
1871                                 wfErrorExit();
1872                         } else {
1873                                 $t = Title::newFromText( $mainpage );
1874                         }
1875                 }
1876
1877                 $cache = new CacheManager( $t );
1878                 if( $cache->isFileCached() ) {
1879                         $msg = '<p style="color: red"><b>'.$msg."<br />\n" .
1880                                 $cachederror . "</b></p>\n";
1881
1882                         $tag = '<div id="article">';
1883                         $text = str_replace(
1884                                 $tag,
1885                                 $tag . $msg,
1886                                 $cache->fetchPageText() );
1887                 }
1888         }
1889
1890         echo $text;
1891         wfErrorExit();
1892 }
1893
1894 ?>