How to use

getDataOut

method

in

org.apache.hadoop.hdfs.server.datanode.fsdataset.ReplicaOutputStreams

if (streams.getDataOut() != null) {
 long flushStartNanos = System.nanoTime();
 streams.flushDataOut();
 dirSyncOnHSyncDone = true;
if (checksumOut != null || streams.getDataOut() != null) {
 datanode.metrics.addFlushNanos(flushTotalNanos);
 if (isSync) {

if (syncOnClose && (streams.getDataOut() != null || checksumOut != null)) {
 datanode.metrics.incrFsyncCount();      
 if (streams.getDataOut() != null) {
  long flushStartNanos = System.nanoTime();
  streams.flushDataOut();

IOUtils.closeStream(streams.getDataOut());

this.checksumSize = diskChecksum.getChecksumSize();
this.out = streams.getDataOut();
if (out instanceof FileOutputStream) {
 this.outFd = ((FileOutputStream)out).getFD();

this.checksumSize = diskChecksum.getChecksumSize();
this.out = streams.getDataOut();
if (out instanceof FileOutputStream) {
 this.outFd = ((FileOutputStream)out).getFD();

ReplicaOutputStreams outputStreams =
  rbw.createStreams(false, DEFAULT_CHECKSUM);
OutputStream dataOutput = outputStreams.getDataOut();

int addSomeBlocks(SimulatedFSDataset fsdataset, int startingBlockId)
  throws IOException {
 int bytesAdded = 0;
 for (int i = startingBlockId; i < startingBlockId+NUMBLOCKS; ++i) {
  ExtendedBlock b = new ExtendedBlock(bpid, i, 0, 0); 
  // we pass expected len as zero, - fsdataset should use the sizeof actual
  // data written
  ReplicaInPipelineInterface bInfo = fsdataset.createRbw(
    StorageType.DEFAULT, b, false).getReplica();
  ReplicaOutputStreams out = bInfo.createStreams(true,
    DataChecksum.newDataChecksum(DataChecksum.Type.CRC32, 512));
  try {
   OutputStream dataOut  = out.getDataOut();
   assertEquals(0, fsdataset.getLength(b));
   for (int j=1; j <= blockIdToLen(i); ++j) {
    dataOut.write(j);
    assertEquals(j, bInfo.getBytesOnDisk()); // correct length even as we write
    bytesAdded++;
   }
  } finally {
   out.close();
  }
  b.setNumBytes(blockIdToLen(i));
  fsdataset.finalizeBlock(b, false);
  assertEquals(blockIdToLen(i), fsdataset.getLength(b));
 }
 return bytesAdded;  
}
int addSomeBlocks(SimulatedFSDataset fsdataset ) throws IOException {