/**
* sendBlock() is used to read block and its metadata and stream the data to either a client or to
* another datanode.
*
* @param out stream to which the block is written to
* @param baseStream optional. if non-null, <code>out</code> is assumed to be a wrapper over this
* stream. This enables optimizations for sending the data, e.g. {@link
* SocketOutputStream#transferToFully(FileChannel, long, int)}.
* @param throttler for sending data.
* @return total bytes reads, including crc.
*/
long sendBlock(DataOutputStream out, OutputStream baseStream, DataTransferThrottler throttler)
throws IOException {
if (out == null) {
throw new IOException("out stream is null");
}
this.throttler = throttler;
long initialOffset = offset;
long totalRead = 0;
OutputStream streamForSendChunks = out;
final long startTime = ClientTraceLog.isInfoEnabled() ? System.nanoTime() : 0;
try {
try {
checksum.writeHeader(out);
if (chunkOffsetOK) {
out.writeLong(offset);
}
out.flush();
} catch (IOException e) { // socket error
throw ioeToSocketException(e);
}
int maxChunksPerPacket;
int pktSize = PacketHeader.PKT_HEADER_LEN;
if (transferToAllowed
&& !verifyChecksum
&& baseStream instanceof SocketOutputStream
&& blockIn instanceof FileInputStream) {
FileChannel fileChannel = ((FileInputStream) blockIn).getChannel();
// blockInPosition also indicates sendChunks() uses transferTo.
blockInPosition = fileChannel.position();
streamForSendChunks = baseStream;
// assure a mininum buffer size.
maxChunksPerPacket =
(Math.max(BUFFER_SIZE, MIN_BUFFER_WITH_TRANSFERTO) + bytesPerChecksum - 1)
/ bytesPerChecksum;
// allocate smaller buffer while using transferTo().
pktSize += checksumSize * maxChunksPerPacket;
} else {
maxChunksPerPacket = Math.max(1, (BUFFER_SIZE + bytesPerChecksum - 1) / bytesPerChecksum);
pktSize += (bytesPerChecksum + checksumSize) * maxChunksPerPacket;
}
ByteBuffer pktBuf = ByteBuffer.allocate(pktSize);
while (endOffset > offset) {
long len = sendChunks(pktBuf, maxChunksPerPacket, streamForSendChunks);
offset += len;
totalRead += len + ((len + bytesPerChecksum - 1) / bytesPerChecksum * checksumSize);
seqno++;
}
try {
// send an empty packet to mark the end of the block
sendChunks(pktBuf, maxChunksPerPacket, streamForSendChunks);
out.flush();
} catch (IOException e) { // socket error
throw ioeToSocketException(e);
}
sentEntireByteRange = true;
} finally {
if (clientTraceFmt != null) {
final long endTime = System.nanoTime();
ClientTraceLog.info(
String.format(clientTraceFmt, totalRead, initialOffset, endTime - startTime));
}
close();
}
blockReadFully = initialOffset == 0 && offset >= replicaVisibleLength;
return totalRead;
}
