Cdb.php

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<?php
abstract class CdbReader {
        public static function open( $fileName ) {
                if ( self::haveExtension() ) {
                        return new CdbReader_DBA( $fileName );
                } else {
                        wfDebug( "Warning: no dba extension found, using emulation.\n" );
                        return new CdbReader_PHP( $fileName );
                }
        }

        public static function haveExtension() {
                if ( !function_exists( 'dba_handlers' ) ) {
                        return false;
                }
                $handlers = dba_handlers();
                if ( !in_array( 'cdb', $handlers ) || !in_array( 'cdb_make', $handlers ) ) {
                        return false;
                }
                return true;
        }

        abstract function __construct( $fileName );

        abstract function close();

        abstract public function get( $key );
}

abstract class CdbWriter {
        public static function open( $fileName ) {
                if ( CdbReader::haveExtension() ) {
                        return new CdbWriter_DBA( $fileName );
                } else {
                        wfDebug( "Warning: no dba extension found, using emulation.\n" );
                        return new CdbWriter_PHP( $fileName );
                }
        }

        abstract function __construct( $fileName );

        abstract public function set( $key, $value );

        abstract public function close();
}

class CdbReader_DBA {
        var $handle;

        function __construct( $fileName ) {
                $this->handle = dba_open( $fileName, 'r-', 'cdb' );
                if ( !$this->handle ) {
                        throw new MWException( 'Unable to open CDB file "' . $fileName . '"' );
                }
        }

        function close() {
                if( isset($this->handle) )
                        dba_close( $this->handle );
                unset( $this->handle );
        }

        function get( $key ) {
                return dba_fetch( $key, $this->handle );
        }
}


class CdbWriter_DBA {
        var $handle, $realFileName, $tmpFileName;

        function __construct( $fileName ) {
                $this->realFileName = $fileName;
                $this->tmpFileName = $fileName . '.tmp.' . mt_rand( 0, 0x7fffffff );
                $this->handle = dba_open( $this->tmpFileName, 'n', 'cdb_make' );
                if ( !$this->handle ) {
                        throw new MWException( 'Unable to open CDB file for write "' . $fileName . '"' );
                }
        }

        function set( $key, $value ) {
                return dba_insert( $key, $value, $this->handle );
        }

        function close() {
                if( isset($this->handle) )
                        dba_close( $this->handle );
                if ( wfIsWindows() ) {
                        unlink( $this->realFileName );
                }
                if ( !rename( $this->tmpFileName, $this->realFileName ) ) {
                        throw new MWException( 'Unable to move the new CDB file into place.' );
                }
                unset( $this->handle );
        }

        function __destruct() {
                if ( isset( $this->handle ) ) {
                        $this->close();
                }
        }
}