/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hdfs;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.BufferOverflowException;
import java.nio.channels.ClosedChannelException;
import java.util.Arrays;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.protocol.datatransfer.PacketHeader;
import org.apache.hadoop.hdfs.util.ByteArrayManager;
import org.apache.htrace.Span;
/****************************************************************
* DFSPacket is used by DataStreamer and DFSOutputStream.
* DFSOutputStream generates packets and then ask DatStreamer
* to send them to datanodes.
****************************************************************/
@InterfaceAudience.Private
class DFSPacket {
public static final long HEART_BEAT_SEQNO = -1L;
private static long[] EMPTY = new long[0];
private final long seqno; // sequence number of buffer in block
private final long offsetInBlock; // offset in block
private boolean syncBlock; // this packet forces the current block to disk
private int numChunks; // number of chunks currently in packet
private final int maxChunks; // max chunks in packet
private byte[] buf;
private final boolean lastPacketInBlock; // is this the last packet in block?
/**
* buf is pointed into like follows:
* (C is checksum data, D is payload data)
*
* [_________CCCCCCCCC________________DDDDDDDDDDDDDDDD___]
* ^ ^ ^ ^
* | checksumPos dataStart dataPos
* checksumStart
*
* Right before sending, we move the checksum data to immediately precede
* the actual data, and then insert the header into the buffer immediately
* preceding the checksum data, so we make sure to keep enough space in
* front of the checksum data to support the largest conceivable header.
*/
private int checksumStart;
private int checksumPos;
private final int dataStart;
private int dataPos;
private long[] traceParents = EMPTY;
private int traceParentsUsed;
private Span span;
/**
* Create a new packet.
*
* @param buf the buffer storing data and checksums
* @param chunksPerPkt maximum number of chunks per packet.
* @param offsetInBlock offset in bytes into the HDFS block.
* @param seqno the sequence number of this packet
* @param checksumSize the size of checksum
* @param lastPacketInBlock if this is the last packet
*/
DFSPacket(byte[] buf, int chunksPerPkt, long offsetInBlock, long seqno,
int checksumSize, boolean lastPacketInBlock) {
this.lastPacketInBlock = lastPacketInBlock;
this.numChunks = 0;
this.offsetInBlock = offsetInBlock;
this.seqno = seqno;
this.buf = buf;
checksumStart = PacketHeader.PKT_MAX_HEADER_LEN;
checksumPos = checksumStart;
dataStart = checksumStart + (chunksPerPkt * checksumSize);
dataPos = dataStart;
maxChunks = chunksPerPkt;
}
/**
* Write data to this packet.
*
* @param inarray input array of data
* @param off the offset of data to write
* @param len the length of data to write
* @throws ClosedChannelException
*/
synchronized void writeData(byte[] inarray, int off, int len)
throws ClosedChannelException {
checkBuffer();
if (dataPos + len > buf.length) {
throw new BufferOverflowException();
}
System.arraycopy(inarray, off, buf, dataPos, len);
dataPos += len;
}
/**
* Write checksums to this packet
*
* @param inarray input array of checksums
* @param off the offset of checksums to write
* @param len the length of checksums to write
* @throws ClosedChannelException
*/
synchronized void writeChecksum(byte[] inarray, int off, int len)
throws ClosedChannelException {
checkBuffer();
if (len == 0) {
return;
}
if (checksumPos + len > dataStart) {
throw new BufferOverflowException();
}
System.arraycopy(inarray, off, buf, checksumPos, len);
checksumPos += len;
}
/**
* Write the full packet, including the header, to the given output stream.
*
* @param stm
* @throws IOException
*/
synchronized void writeTo(DataOutputStream stm) throws IOException {
checkBuffer();
final int dataLen = dataPos - dataStart;
final int checksumLen = checksumPos - checksumStart;
final int pktLen = HdfsConstants.BYTES_IN_INTEGER + dataLen + checksumLen;
PacketHeader header = new PacketHeader(
pktLen, offsetInBlock, seqno, lastPacketInBlock, dataLen, syncBlock);
if (checksumPos != dataStart) {
// Move the checksum to cover the gap. This can happen for the last
// packet or during an hflush/hsync call.
System.arraycopy(buf, checksumStart, buf,
dataStart - checksumLen , checksumLen);
checksumPos = dataStart;
checksumStart = checksumPos - checksumLen;
}
final int headerStart = checksumStart - header.getSerializedSize();
assert checksumStart + 1 >= header.getSerializedSize();
assert headerStart >= 0;
assert headerStart + header.getSerializedSize() == checksumStart;
// Copy the header data into the buffer immediately preceding the checksum
// data.
System.arraycopy(header.getBytes(), 0, buf, headerStart,
header.getSerializedSize());
// corrupt the data for testing.
if (DFSClientFaultInjector.get().corruptPacket()) {
buf[headerStart+header.getSerializedSize() + checksumLen + dataLen-1] ^= 0xff;
}
// Write the now contiguous full packet to the output stream.
stm.write(buf, headerStart, header.getSerializedSize() + checksumLen + dataLen);
// undo corruption.
if (DFSClientFaultInjector.get().uncorruptPacket()) {
buf[headerStart+header.getSerializedSize() + checksumLen + dataLen-1] ^= 0xff;
}
}
private synchronized void checkBuffer() throws ClosedChannelException {
if (buf == null) {
throw new ClosedChannelException();
}
}
/**
* Release the buffer in this packet to ByteArrayManager.
*
* @param bam
*/
synchronized void releaseBuffer(ByteArrayManager bam) {
bam.release(buf);
buf = null;
}
/**
* get the packet's last byte's offset in the block
*
* @return the packet's last byte's offset in the block
*/
synchronized long getLastByteOffsetBlock() {
return offsetInBlock + dataPos - dataStart;
}
/**
* Check if this packet is a heart beat packet
*
* @return true if the sequence number is HEART_BEAT_SEQNO
*/
boolean isHeartbeatPacket() {
return seqno == HEART_BEAT_SEQNO;
}
/**
* check if this packet is the last packet in block
*
* @return true if the packet is the last packet
*/
boolean isLastPacketInBlock(){
return lastPacketInBlock;
}
/**
* get sequence number of this packet
*
* @return the sequence number of this packet
*/
long getSeqno(){
return seqno;
}
/**
* get the number of chunks this packet contains
*
* @return the number of chunks in this packet
*/
synchronized int getNumChunks(){
return numChunks;
}
/**
* increase the number of chunks by one
*/
synchronized void incNumChunks(){
numChunks++;
}
/**
* get the maximum number of packets
*
* @return the maximum number of packets
*/
int getMaxChunks(){
return maxChunks;
}
/**
* set if to sync block
*
* @param syncBlock if to sync block
*/
synchronized void setSyncBlock(boolean syncBlock){
this.syncBlock = syncBlock;
}
@Override
public String toString() {
return "packet seqno: " + this.seqno +
" offsetInBlock: " + this.offsetInBlock +
" lastPacketInBlock: " + this.lastPacketInBlock +
" lastByteOffsetInBlock: " + this.getLastByteOffsetBlock();
}
/**
* Add a trace parent span for this packet.<p/>
*
* Trace parent spans for a packet are the trace spans responsible for
* adding data to that packet. We store them as an array of longs for
* efficiency.<p/>
*
* Protected by the DFSOutputStream dataQueue lock.
*/
public void addTraceParent(Span span) {
if (span == null) {
return;
}
addTraceParent(span.getSpanId());
}
public void addTraceParent(long id) {
if (traceParentsUsed == traceParents.length) {
int newLength = (traceParents.length == 0) ? 8 :
traceParents.length * 2;
traceParents = Arrays.copyOf(traceParents, newLength);
}
traceParents[traceParentsUsed] = id;
traceParentsUsed++;
}
/**
* Get the trace parent spans for this packet.<p/>
*
* Will always be non-null.<p/>
*
* Protected by the DFSOutputStream dataQueue lock.
*/
public long[] getTraceParents() {
// Remove duplicates from the array.
int len = traceParentsUsed;
Arrays.sort(traceParents, 0, len);
int i = 0, j = 0;
long prevVal = 0; // 0 is not a valid span id
while (true) {
if (i == len) {
break;
}
long val = traceParents[i];
if (val != prevVal) {
traceParents[j] = val;
j++;
prevVal = val;
}
i++;
}
if (j < traceParents.length) {
traceParents = Arrays.copyOf(traceParents, j);
traceParentsUsed = traceParents.length;
}
return traceParents;
}
public void setTraceSpan(Span span) {
this.span = span;
}
public Span getTraceSpan() {
return span;
}
}