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();
        }
    }
}