question: private void openLogFile ( ) throws IOException { try { close ( ) ; } catch ( IOException e ) { } logName = versionName ( logfilePrefix ) ; log = new RandomAccessFile ( logName , "rw" ) ; logFD = log . getFD ( ) ; if ( logBytes == 0 ) { format = FORMAT_PADDED ; writeInt ( log , MAGIC ) ; writeInt ( log , format ) ; logBytes = ( intBytes + intBytes ) ; } else { log . seek ( logBytes ) ; } log . setLength ( logBytes ) ; log . write ( zeroBuf ) ; logFD . sync ( ) ; }
target:  Opens the incremental update log file in read/write mode.  If the file does not exist, it is created.