How to use

ReplicaOutputStreams

in

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

  crcOut.getChannel().position(crcDiskSize);
 return new ReplicaOutputStreams(blockOut, crcOut, checksum,
   getVolume(), fileIoProvider);
} catch (IOException e) {

/**
 * Sets the offset in the meta file so that the
 * last checksum will be overwritten.
 */
@Override // FsDatasetSpi
public void adjustCrcChannelPosition(ExtendedBlock b, ReplicaOutputStreams streams, 
  int checksumSize) throws IOException {
 FileOutputStream file = (FileOutputStream)streams.getChecksumOut();
 FileChannel channel = file.getChannel();
 long oldPos = channel.position();
 long newPos = oldPos - checksumSize;
 if (LOG.isDebugEnabled()) {
  LOG.debug("Changing meta file offset of block " + b + " from " +
    oldPos + " to " + newPos);
 }
 channel.position(newPos);
}

if (syncOnClose && (streams.getDataOut() != null || checksumOut != null)) {
 datanode.metrics.incrFsyncCount();      
  if (syncOnClose) {
   long fsyncStartNanos = flushEndNanos;
   streams.syncChecksumOut();
   datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);
 if (streams.getDataOut() != null) {
  long flushStartNanos = System.nanoTime();
  streams.flushDataOut();
  long flushEndNanos = System.nanoTime();
  if (syncOnClose) {
   long fsyncStartNanos = flushEndNanos;
   streams.syncDataOut();
   datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);
  streams.closeDataStream();
 streams.close();

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

if (checksumReceivedLen == 0 && !streams.isTransientStorage()) {
  && streams.isTransientStorage();
try {
 long onDiskLen = replicaInfo.getBytesOnDisk();
  streams.writeDataToDisk(dataBuf.array(),
    startByteToDisk, numBytesToDisk);
  long duration = Time.monotonicNow() - begin;

this.diskChecksum = streams.getChecksum();
this.needsChecksumTranslation = !clientChecksum.equals(diskChecksum);
this.bytesPerChecksum = diskChecksum.getBytesPerChecksum();
this.checksumSize = diskChecksum.getChecksumSize();
this.out = streams.getDataOut();
if (out instanceof FileOutputStream) {
 this.outFd = ((FileOutputStream)out).getFD();
  streams.getChecksumOut(), HdfsConstants.SMALL_BUFFER_SIZE));

if (isSync) {
 long fsyncStartNanos = flushEndNanos;
 streams.syncChecksumOut();
 datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);
if (isSync) {
 long fsyncStartNanos = flushEndNanos;
 streams.syncDataOut();
 datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);

this.diskChecksum = streams.getChecksum();
this.needsChecksumTranslation = !clientChecksum.equals(diskChecksum);
this.bytesPerChecksum = diskChecksum.getBytesPerChecksum();
  streams.getChecksumOut(), DFSUtilClient.getSmallBufferSize(
  datanode.getConf())));

 streams = replicaInfo.createStreams(true,
   DataChecksum.newDataChecksum(DataChecksum.Type.CRC32, 512));
 streams.getChecksumOut().write('a');
 dn.data.initReplicaRecovery(new RecoveringBlock(block, null, RECOVERY_ID+1));
 try {
   anyBoolean(), any(DatanodeID[].class), any(String[].class));
} finally {
 streams.close();

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 {

IOUtils.closeStream(streams.getDataOut());

if (checksumReceivedLen == 0 && !streams.isTransientStorage()) {
  && streams.isTransientStorage();
try {
 long onDiskLen = replicaInfo.getBytesOnDisk();

this.diskChecksum = streams.getChecksum();
this.needsChecksumTranslation = !clientChecksum.equals(diskChecksum);
this.bytesPerChecksum = diskChecksum.getBytesPerChecksum();
this.checksumSize = diskChecksum.getChecksumSize();
this.out = streams.getDataOut();
if (out instanceof FileOutputStream) {
 this.outFd = ((FileOutputStream)out).getFD();
  streams.getChecksumOut(), HdfsConstants.SMALL_BUFFER_SIZE));

if (isSync) {
 long fsyncStartNanos = flushEndNanos;
 streams.syncChecksumOut();
 datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);
if (isSync) {
 long fsyncStartNanos = flushEndNanos;
 streams.syncDataOut();
 datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);

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

if (checksumReceivedLen == 0 && !streams.isTransientStorage()) {
  && streams.isTransientStorage();
try {
 long onDiskLen = replicaInfo.getBytesOnDisk();

@Override
public ReplicaOutputStreams createStreams(boolean isCreate,
  DataChecksum requestedChecksum) throws IOException {
 return new ReplicaOutputStreams(null, null, requestedChecksum, false);
}

if (syncOnClose) {
 long fsyncStartNanos = flushEndNanos;
 streams.syncChecksumOut();
 datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);
if (syncOnClose) {
 long fsyncStartNanos = flushEndNanos;
 streams.syncDataOut();
 datanode.metrics.addFsyncNanos(System.nanoTime() - fsyncStartNanos);

/**
 * Sets the offset in the meta file so that the
 * last checksum will be overwritten.
 */
@Override // FsDatasetSpi
public void adjustCrcChannelPosition(ExtendedBlock b, ReplicaOutputStreams streams, 
  int checksumSize) throws IOException {
 FileOutputStream file = (FileOutputStream)streams.getChecksumOut();
 FileChannel channel = file.getChannel();
 long oldPos = channel.position();
 long newPos = oldPos - checksumSize;
 if (LOG.isDebugEnabled()) {
  LOG.debug("Changing meta file offset of block " + b + " from " +
    oldPos + " to " + newPos);
 }
 channel.position(newPos);
}

@Override
synchronized public ReplicaOutputStreams createStreams(boolean isCreate,
  DataChecksum requestedChecksum) throws IOException {
 if (finalized) {
  throw new IOException("Trying to write to a finalized replica "
    + theBlock);
 } else {
  SimulatedOutputStream crcStream = new SimulatedOutputStream();
  return new ReplicaOutputStreams(oStream, crcStream, requestedChecksum,
    getStorage(theBlock).getVolume().isTransientStorage());
 }
}