public synchronized void flush() throws IOException {
        if (writer != null) {
            writer.flush();
        }
    }
This is called when we want to rotate the output file to
start writing the next file.  There are two scenarios when
we do this:
<UL>
<LI> initial case, when we have no file
<LI> when we have filled the file and want to rotate it
</UL>
logserver/src/main/java/com/yahoo/logserver/handlers/archive/LogWriter.java