public boolean flush() {
        boolean ret = true;
        PrintWriter out = null;
        
        // Save source water marks
        try {
            // Backup the original file
            if (file.exists()) {
                if (fileOriginal.exists()) {
                    fileOriginal.delete();
                }

                file.renameTo(fileOriginal);
            }

            // Overwrite the existing file
            out = new PrintWriter(new FileOutputStream(file));
            for (String source : sourceWaterMarkMap.keySet()) {
                WaterMarkEntry wmEntry = sourceWaterMarkMap.get(source);
                out.println(wmEntry);
            }
            out.flush();
        } catch (IOException ioe) {
            logger.error("Failed to flush water marks", ioe);
            ret = false;
        } finally {
            if (out != null) {
                out.close();
                out = null;
            }
        }

        return ret;
    }
public boolean flush ( ) { boolean ret = true ; PrintWriter out = null ; try { if ( file . exists ( ) ) { if ( fileOriginal . exists ( ) ) { fileOriginal . delete ( ) ; } file . renameTo ( fileOriginal ) ; } out = new PrintWriter ( new FileOutputStream ( file ) ) ; for ( String source : sourceWaterMarkMap . keySet ( ) ) { WaterMarkEntry wmEntry = sourceWaterMarkMap . get ( source ) ; out . println ( wmEntry ) ; } out . flush ( ) ; } catch ( IOException ioe ) { logger . error ( "Failed to flush water marks" , ioe ) ; ret = false ; } finally { if ( out != null ) { out . close ( ) ; out = null ; } } return ret ; }
Flushes low water marks and high water marks for all the sources.

@return <tt>true</tt> if flush is successful.