DatabaseMysqlBase.php

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<?php
abstract class DatabaseMysqlBase extends DatabaseBase {
    protected $lastKnownSlavePos;
 
    protected $mFakeSlaveLag = null;
 
    protected $mFakeMaster = false;
 
    function getType() {
        return 'mysql';
    }
 
    function open( $server, $user, $password, $dbName ) {
        global $wgAllDBsAreLocalhost, $wgSQLMode;
        wfProfileIn( __METHOD__ );
 
        # Debugging hack -- fake cluster
        if ( $wgAllDBsAreLocalhost ) {
            $realServer = 'localhost';
        } else {
            $realServer = $server;
        }
        $this->close();
        $this->mServer = $server;
        $this->mUser = $user;
        $this->mPassword = $password;
        $this->mDBname = $dbName;
 
        wfProfileIn( "dbconnect-$server" );
 
        # The kernel's default SYN retransmission period is far too slow for us,
        # so we use a short timeout plus a manual retry. Retrying means that a small
        # but finite rate of SYN packet loss won't cause user-visible errors.
        $this->mConn = false;
        $this->installErrorHandler();
        try {
            $this->mConn = $this->mysqlConnect( $realServer );
        } catch ( Exception $ex ) {
            wfProfileOut( "dbconnect-$server" );
            wfProfileOut( __METHOD__ );
            $this->restoreErrorHandler();
            throw $ex;
        }
        $error = $this->restoreErrorHandler();
 
        wfProfileOut( "dbconnect-$server" );
 
        # Always log connection errors
        if ( !$this->mConn ) {
            if ( !$error ) {
                $error = $this->lastError();
            }
            wfLogDBError( "Error connecting to {$this->mServer}: $error" );
            wfDebug( "DB connection error\n" .
                "Server: $server, User: $user, Password: " .
                substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 
            wfProfileOut( __METHOD__ );
 
            $this->reportConnectionError( $error );
        }
 
        if ( $dbName != '' ) {
            wfSuppressWarnings();
            $success = $this->selectDB( $dbName );
            wfRestoreWarnings();
            if ( !$success ) {
                wfLogDBError( "Error selecting database $dbName on server {$this->mServer}" );
                wfDebug( "Error selecting database $dbName on server {$this->mServer} " .
                    "from client host " . wfHostname() . "\n" );
 
                wfProfileOut( __METHOD__ );
 
                $this->reportConnectionError( "Error selecting database $dbName" );
            }
        }
 
        // Tell the server what we're communicating with
        if ( !$this->connectInitCharset() ) {
            $this->reportConnectionError( "Error setting character set" );
        }
 
        // Set SQL mode, default is turning them all off, can be overridden or skipped with null
        if ( is_string( $wgSQLMode ) ) {
            $mode = $this->addQuotes( $wgSQLMode );
            // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
            $success = $this->doQuery( "SET sql_mode = $mode", __METHOD__ );
            if ( !$success ) {
                wfLogDBError( "Error setting sql_mode to $mode on server {$this->mServer}" );
                wfProfileOut( __METHOD__ );
                $this->reportConnectionError( "Error setting sql_mode to $mode" );
            }
        }
 
        $this->mOpened = true;
        wfProfileOut( __METHOD__ );
 
        return true;
    }
 
    protected function connectInitCharset() {
        global $wgDBmysql5;
 
        if ( $wgDBmysql5 ) {
            // Tell the server we're communicating with it in UTF-8.
            // This may engage various charset conversions.
            return $this->mysqlSetCharset( 'utf8' );
        } else {
            return $this->mysqlSetCharset( 'binary' );
        }
    }
 
    abstract protected function mysqlConnect( $realServer );
 
    abstract protected function mysqlSetCharset( $charset );
 
    function freeResult( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        wfSuppressWarnings();
        $ok = $this->mysqlFreeResult( $res );
        wfRestoreWarnings();
        if ( !$ok ) {
            throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
        }
    }
 
    abstract protected function mysqlFreeResult( $res );
 
    function fetchObject( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        wfSuppressWarnings();
        $row = $this->mysqlFetchObject( $res );
        wfRestoreWarnings();
 
        $errno = $this->lastErrno();
        // Unfortunately, mysql_fetch_object does not reset the last errno.
        // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
        // these are the only errors mysql_fetch_object can cause.
        // See http://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
        if ( $errno == 2000 || $errno == 2013 ) {
            throw new DBUnexpectedError(
                $this,
                'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
            );
        }
 
        return $row;
    }
 
    abstract protected function mysqlFetchObject( $res );
 
    function fetchRow( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        wfSuppressWarnings();
        $row = $this->mysqlFetchArray( $res );
        wfRestoreWarnings();
 
        $errno = $this->lastErrno();
        // Unfortunately, mysql_fetch_array does not reset the last errno.
        // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
        // these are the only errors mysql_fetch_array can cause.
        // See http://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
        if ( $errno == 2000 || $errno == 2013 ) {
            throw new DBUnexpectedError(
                $this,
                'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
            );
        }
 
        return $row;
    }
 
    abstract protected function mysqlFetchArray( $res );
 
    function numRows( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
        wfSuppressWarnings();
        $n = $this->mysqlNumRows( $res );
        wfRestoreWarnings();
 
        // Unfortunately, mysql_num_rows does not reset the last errno.
        // We are not checking for any errors here, since
        // these are no errors mysql_num_rows can cause.
        // See http://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
        // See https://bugzilla.wikimedia.org/42430
        return $n;
    }
 
    abstract protected function mysqlNumRows( $res );
 
    function numFields( $res ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $this->mysqlNumFields( $res );
    }
 
    abstract protected function mysqlNumFields( $res );
 
    function fieldName( $res, $n ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $this->mysqlFieldName( $res, $n );
    }
 
    abstract protected function mysqlFieldName( $res, $n );
 
    public function fieldType( $res, $n ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $this->mysqlFieldType( $res, $n );
    }
 
    abstract protected function mysqlFieldType( $res, $n );
 
    function dataSeek( $res, $row ) {
        if ( $res instanceof ResultWrapper ) {
            $res = $res->result;
        }
 
        return $this->mysqlDataSeek( $res, $row );
    }
 
    abstract protected function mysqlDataSeek( $res, $row );
 
    function lastError() {
        if ( $this->mConn ) {
            # Even if it's non-zero, it can still be invalid
            wfSuppressWarnings();
            $error = $this->mysqlError( $this->mConn );
            if ( !$error ) {
                $error = $this->mysqlError();
            }
            wfRestoreWarnings();
        } else {
            $error = $this->mysqlError();
        }
        if ( $error ) {
            $error .= ' (' . $this->mServer . ')';
        }
 
        return $error;
    }
 
    abstract protected function mysqlError( $conn = null );
 
    function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
        return $this->nativeReplace( $table, $rows, $fname );
    }
 
    public function estimateRowCount( $table, $vars = '*', $conds = '',
        $fname = __METHOD__, $options = array()
    ) {
        $options['EXPLAIN'] = true;
        $res = $this->select( $table, $vars, $conds, $fname, $options );
        if ( $res === false ) {
            return false;
        }
        if ( !$this->numRows( $res ) ) {
            return 0;
        }
 
        $rows = 1;
        foreach ( $res as $plan ) {
            $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
        }
 
        return $rows;
    }
 
    function fieldInfo( $table, $field ) {
        $table = $this->tableName( $table );
        $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
        if ( !$res ) {
            return false;
        }
        $n = $this->mysqlNumFields( $res->result );
        for ( $i = 0; $i < $n; $i++ ) {
            $meta = $this->mysqlFetchField( $res->result, $i );
            if ( $field == $meta->name ) {
                return new MySQLField( $meta );
            }
        }
 
        return false;
    }
 
    abstract protected function mysqlFetchField( $res, $n );
 
    function indexInfo( $table, $index, $fname = __METHOD__ ) {
        # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
        # SHOW INDEX should work for 3.x and up:
        # http://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
        $table = $this->tableName( $table );
        $index = $this->indexName( $index );
 
        $sql = 'SHOW INDEX FROM ' . $table;
        $res = $this->query( $sql, $fname );
 
        if ( !$res ) {
            return null;
        }
 
        $result = array();
 
        foreach ( $res as $row ) {
            if ( $row->Key_name == $index ) {
                $result[] = $row;
            }
        }
 
        return empty( $result ) ? false : $result;
    }
 
    function strencode( $s ) {
        $sQuoted = $this->mysqlRealEscapeString( $s );
 
        if ( $sQuoted === false ) {
            $this->ping();
            $sQuoted = $this->mysqlRealEscapeString( $s );
        }
 
        return $sQuoted;
    }
 
    public function addIdentifierQuotes( $s ) {
        // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
        // Remove NUL bytes and escape backticks by doubling
        return '`' . str_replace( array( "\0", '`' ), array( '', '``' ), $s ) . '`';
    }
 
    public function isQuotedIdentifier( $name ) {
        return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
    }
 
    function ping() {
        $ping = $this->mysqlPing();
        if ( $ping ) {
            return true;
        }
 
        $this->closeConnection();
        $this->mOpened = false;
        $this->mConn = false;
        $this->open( $this->mServer, $this->mUser, $this->mPassword, $this->mDBname );
 
        return true;
    }
 
    abstract protected function mysqlPing();
 
    public function setFakeSlaveLag( $lag ) {
        $this->mFakeSlaveLag = $lag;
    }
 
    public function setFakeMaster( $enabled = true ) {
        $this->mFakeMaster = $enabled;
    }
 
    function getLag() {
        if ( !is_null( $this->mFakeSlaveLag ) ) {
            wfDebug( "getLag: fake slave lagged {$this->mFakeSlaveLag} seconds\n" );
 
            return $this->mFakeSlaveLag;
        }
 
        return $this->getLagFromSlaveStatus();
    }
 
    function getLagFromSlaveStatus() {
        $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
        if ( !$res ) {
            return false;
        }
        $row = $res->fetchObject();
        if ( !$row ) {
            return false;
        }
        if ( strval( $row->Seconds_Behind_Master ) === '' ) {
            return false;
        } else {
            return intval( $row->Seconds_Behind_Master );
        }
    }
 
    function getLagFromProcesslist() {
        wfDeprecated( __METHOD__, '1.19' );
        $res = $this->query( 'SHOW PROCESSLIST', __METHOD__ );
        if ( !$res ) {
            return false;
        }
        # Find slave SQL thread
        foreach ( $res as $row ) {
            /* This should work for most situations - when default db
             * for thread is not specified, it had no events executed,
             * and therefore it doesn't know yet how lagged it is.
             *
             * Relay log I/O thread does not select databases.
             */
            if ( $row->User == 'system user' &&
                $row->State != 'Waiting for master to send event' &&
                $row->State != 'Connecting to master' &&
                $row->State != 'Queueing master event to the relay log' &&
                $row->State != 'Waiting for master update' &&
                $row->State != 'Requesting binlog dump' &&
                $row->State != 'Waiting to reconnect after a failed master event read' &&
                $row->State != 'Reconnecting after a failed master event read' &&
                $row->State != 'Registering slave on master'
            ) {
                # This is it, return the time (except -ve)
                if ( $row->Time > 0x7fffffff ) {
                    return false;
                } else {
                    return $row->Time;
                }
            }
        }
 
        return false;
    }
 
    function masterPosWait( DBMasterPos $pos, $timeout ) {
        if ( $this->lastKnownSlavePos && $this->lastKnownSlavePos->hasReached( $pos ) ) {
            return '0'; // http://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html
        }
 
        wfProfileIn( __METHOD__ );
        # Commit any open transactions
        $this->commit( __METHOD__, 'flush' );
 
        if ( !is_null( $this->mFakeSlaveLag ) ) {
            $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
 
            if ( $wait > $timeout * 1e6 ) {
                wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
                wfProfileOut( __METHOD__ );
 
                return -1;
            } elseif ( $wait > 0 ) {
                wfDebug( "Fake slave waiting $wait us\n" );
                usleep( $wait );
                wfProfileOut( __METHOD__ );
 
                return 1;
            } else {
                wfDebug( "Fake slave up to date ($wait us)\n" );
                wfProfileOut( __METHOD__ );
 
                return 0;
            }
        }
 
        # Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
        $encFile = $this->addQuotes( $pos->file );
        $encPos = intval( $pos->pos );
        $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
        $res = $this->doQuery( $sql );
 
        $status = false;
        if ( $res && $row = $this->fetchRow( $res ) ) {
            $status = $row[0]; // can be NULL, -1, or 0+ per the MySQL manual
            if ( ctype_digit( $status ) ) { // success
                $this->lastKnownSlavePos = $pos;
            }
        }
 
        wfProfileOut( __METHOD__ );
 
        return $status;
    }
 
    function getSlavePos() {
        if ( !is_null( $this->mFakeSlaveLag ) ) {
            $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
            wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
 
            return $pos;
        }
 
        $res = $this->query( 'SHOW SLAVE STATUS', 'DatabaseBase::getSlavePos' );
        $row = $this->fetchObject( $res );
 
        if ( $row ) {
            $pos = isset( $row->Exec_master_log_pos )
                ? $row->Exec_master_log_pos
                : $row->Exec_Master_Log_Pos;
 
            return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos );
        } else {
            return false;
        }
    }
 
    function getMasterPos() {
        if ( $this->mFakeMaster ) {
            return new MySQLMasterPos( 'fake', microtime( true ) );
        }
 
        $res = $this->query( 'SHOW MASTER STATUS', 'DatabaseBase::getMasterPos' );
        $row = $this->fetchObject( $res );
 
        if ( $row ) {
            return new MySQLMasterPos( $row->File, $row->Position );
        } else {
            return false;
        }
    }
 
    function useIndexClause( $index ) {
        return "FORCE INDEX (" . $this->indexName( $index ) . ")";
    }
 
    function lowPriorityOption() {
        return 'LOW_PRIORITY';
    }
 
    public function getSoftwareLink() {
        // MariaDB includes its name in its version string (sent when the connection is opened),
        // and this is how MariaDB's version of the mysql command-line client identifies MariaDB
        // servers (see the mariadb_connection() function in libmysql/libmysql.c).
        $version = $this->getServerVersion();
        if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
            return '[{{int:version-db-mariadb-url}} MariaDB]';
        }
 
        // Percona Server's version suffix is not very distinctive, and @@version_comment
        // doesn't give the necessary info for source builds, so assume the server is MySQL.
        // (Even Percona's version of mysql doesn't try to make the distinction.)
        return '[{{int:version-db-mysql-url}} MySQL]';
    }
 
    public function setSessionOptions( array $options ) {
        if ( isset( $options['connTimeout'] ) ) {
            $timeout = (int)$options['connTimeout'];
            $this->query( "SET net_read_timeout=$timeout" );
            $this->query( "SET net_write_timeout=$timeout" );
        }
    }
 
    public function streamStatementEnd( &$sql, &$newLine ) {
        if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
            preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
            $this->delimiter = $m[1];
            $newLine = '';
        }
 
        return parent::streamStatementEnd( $sql, $newLine );
    }
 
    public function lockIsFree( $lockName, $method ) {
        $lockName = $this->addQuotes( $lockName );
        $result = $this->query( "SELECT IS_FREE_LOCK($lockName) AS lockstatus", $method );
        $row = $this->fetchObject( $result );
 
        return ( $row->lockstatus == 1 );
    }
 
    public function lock( $lockName, $method, $timeout = 5 ) {
        $lockName = $this->addQuotes( $lockName );
        $result = $this->query( "SELECT GET_LOCK($lockName, $timeout) AS lockstatus", $method );
        $row = $this->fetchObject( $result );
 
        if ( $row->lockstatus == 1 ) {
            return true;
        } else {
            wfDebug( __METHOD__ . " failed to acquire lock\n" );
 
            return false;
        }
    }
 
    public function unlock( $lockName, $method ) {
        $lockName = $this->addQuotes( $lockName );
        $result = $this->query( "SELECT RELEASE_LOCK($lockName) as lockstatus", $method );
        $row = $this->fetchObject( $result );
 
        return ( $row->lockstatus == 1 );
    }
 
    public function lockTables( $read, $write, $method, $lowPriority = true ) {
        $items = array();
 
        foreach ( $write as $table ) {
            $tbl = $this->tableName( $table ) .
                ( $lowPriority ? ' LOW_PRIORITY' : '' ) .
                ' WRITE';
            $items[] = $tbl;
        }
        foreach ( $read as $table ) {
            $items[] = $this->tableName( $table ) . ' READ';
        }
        $sql = "LOCK TABLES " . implode( ',', $items );
        $this->query( $sql, $method );
 
        return true;
    }
 
    public function unlockTables( $method ) {
        $this->query( "UNLOCK TABLES", $method );
 
        return true;
    }
 
    public function getSearchEngine() {
        return 'SearchMySQL';
    }
 
    public function setBigSelects( $value = true ) {
        if ( $value === 'default' ) {
            if ( $this->mDefaultBigSelects === null ) {
                # Function hasn't been called before so it must already be set to the default
                return;
            } else {
                $value = $this->mDefaultBigSelects;
            }
        } elseif ( $this->mDefaultBigSelects === null ) {
            $this->mDefaultBigSelects = (bool)$this->selectField( false, '@@sql_big_selects' );
        }
        $encValue = $value ? '1' : '0';
        $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
    }
 
    function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__ ) {
        if ( !$conds ) {
            throw new DBUnexpectedError( $this, 'DatabaseBase::deleteJoin() called with empty $conds' );
        }
 
        $delTable = $this->tableName( $delTable );
        $joinTable = $this->tableName( $joinTable );
        $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
 
        if ( $conds != '*' ) {
            $sql .= ' AND ' . $this->makeList( $conds, LIST_AND );
        }
 
        return $this->query( $sql, $fname );
    }
 
    public function upsert( $table, array $rows, array $uniqueIndexes,
        array $set, $fname = __METHOD__
    ) {
        if ( !count( $rows ) ) {
            return true; // nothing to do
        }
 
        if ( !is_array( reset( $rows ) ) ) {
            $rows = array( $rows );
        }
 
        $table = $this->tableName( $table );
        $columns = array_keys( $rows[0] );
 
        $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
        $rowTuples = array();
        foreach ( $rows as $row ) {
            $rowTuples[] = '(' . $this->makeList( $row ) . ')';
        }
        $sql .= implode( ',', $rowTuples );
        $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, LIST_SET );
 
        return (bool)$this->query( $sql, $fname );
    }
 
    function getServerUptime() {
        $vars = $this->getMysqlStatus( 'Uptime' );
 
        return (int)$vars['Uptime'];
    }
 
    function wasDeadlock() {
        return $this->lastErrno() == 1213;
    }
 
    function wasLockTimeout() {
        return $this->lastErrno() == 1205;
    }
 
    function wasErrorReissuable() {
        return $this->lastErrno() == 2013 || $this->lastErrno() == 2006;
    }
 
    function wasReadOnlyError() {
        return $this->lastErrno() == 1223 ||
            ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
    }
 
    function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = __METHOD__ ) {
        $tmp = $temporary ? 'TEMPORARY ' : '';
        $newName = $this->addIdentifierQuotes( $newName );
        $oldName = $this->addIdentifierQuotes( $oldName );
        $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
 
        return $this->query( $query, $fname );
    }
 
    function listTables( $prefix = null, $fname = __METHOD__ ) {
        $result = $this->query( "SHOW TABLES", $fname );
 
        $endArray = array();
 
        foreach ( $result as $table ) {
            $vars = get_object_vars( $table );
            $table = array_pop( $vars );
 
            if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
                $endArray[] = $table;
            }
        }
 
        return $endArray;
    }
 
    public function dropTable( $tableName, $fName = __METHOD__ ) {
        if ( !$this->tableExists( $tableName, $fName ) ) {
            return false;
        }
 
        return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
    }
 
    protected function getDefaultSchemaVars() {
        $vars = parent::getDefaultSchemaVars();
        $vars['wgDBTableOptions'] = str_replace( 'TYPE', 'ENGINE', $GLOBALS['wgDBTableOptions'] );
        $vars['wgDBTableOptions'] = str_replace(
            'CHARSET=mysql4',
            'CHARSET=binary',
            $vars['wgDBTableOptions']
        );
 
        return $vars;
    }
 
    function getMysqlStatus( $which = "%" ) {
        $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
        $status = array();
 
        foreach ( $res as $row ) {
            $status[$row->Variable_name] = $row->Value;
        }
 
        return $status;
    }
 
    public function listViews( $prefix = null, $fname = __METHOD__ ) {
 
        if ( !isset( $this->allViews ) ) {
 
            // The name of the column containing the name of the VIEW
            $propertyName = 'Tables_in_' . $this->mDBname;
 
            // Query for the VIEWS
            $result = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
            $this->allViews = array();
            while ( ( $row = $this->fetchRow( $result ) ) !== false ) {
                array_push( $this->allViews, $row[$propertyName] );
            }
        }
 
        if ( is_null( $prefix ) || $prefix === '' ) {
            return $this->allViews;
        }
 
        $filteredViews = array();
        foreach ( $this->allViews as $viewName ) {
            // Does the name of this VIEW start with the table-prefix?
            if ( strpos( $viewName, $prefix ) === 0 ) {
                array_push( $filteredViews, $viewName );
            }
        }
 
        return $filteredViews;
    }
 
    public function isView( $name, $prefix = null ) {
        return in_array( $name, $this->listViews( $prefix ) );
    }
}
 
class MySQLField implements Field {
    private $name, $tablename, $default, $max_length, $nullable,
        $is_pk, $is_unique, $is_multiple, $is_key, $type, $binary;
 
    function __construct( $info ) {
        $this->name = $info->name;
        $this->tablename = $info->table;
        $this->default = $info->def;
        $this->max_length = $info->max_length;
        $this->nullable = !$info->not_null;
        $this->is_pk = $info->primary_key;
        $this->is_unique = $info->unique_key;
        $this->is_multiple = $info->multiple_key;
        $this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
        $this->type = $info->type;
        $this->binary = isset( $info->binary ) ? $info->binary : false;
    }
 
    function name() {
        return $this->name;
    }
 
    function tableName() {
        return $this->tableName;
    }
 
    function type() {
        return $this->type;
    }
 
    function isNullable() {
        return $this->nullable;
    }
 
    function defaultValue() {
        return $this->default;
    }
 
    function isKey() {
        return $this->is_key;
    }
 
    function isMultipleKey() {
        return $this->is_multiple;
    }
 
    function isBinary() {
        return $this->binary;
    }
}
 
class MySQLMasterPos implements DBMasterPos {
    public $file;
 
    public $pos;
 
    function __construct( $file, $pos ) {
        $this->file = $file;
        $this->pos = $pos;
    }
 
    function __toString() {
        // e.g db1034-bin.000976/843431247
        return "{$this->file}/{$this->pos}";
    }
 
    protected function getCoordinates() {
        $m = array();
        if ( preg_match( '!\.(\d+)/(\d+)$!', (string)$this, $m ) ) {
            return array( (int)$m[1], (int)$m[2] );
        }
 
        return false;
    }
 
    function hasReached( MySQLMasterPos $pos ) {
        $thisPos = $this->getCoordinates();
        $thatPos = $pos->getCoordinates();
 
        return ( $thisPos && $thatPos && $thisPos >= $thatPos );
    }
}