slumberdb/slumberdb-service-model/src/main/java/org/boon/slumberdb/stores/log/BatchFileWriter.java
public boolean syncToDisk() {

        /** if we have a stream and we are dirty then flush. */
        if (outputStream != null && dirty) {

            try {
                //outputStream.flush ();

                if (outputStream instanceof FileChannel) {
                    FileChannel channel = (FileChannel) outputStream;
                    channel.force(true);
                }
                dirty = false;
                return true;
            } catch (Exception ex) {
                cleanupOutputStream();
                return false;
            }
        } else {
            return false;
        }
    }
public boolean syncToDisk() {

        /** if we have a stream and we are dirty then flush. */
        if (outputStream != null && dirty) {

            try {
                //outputStream.flush ();

                if (outputStream instanceof FileChannel) {
                    FileChannel channel = (FileChannel) outputStream;
                    channel.force(true);
                }
                dirty = false;
                return true;
            } catch (Exception ex) {
                cleanupOutputStream();
                return false;
            }
        } else {
            return false;
        }
    }
flush to disk.