hadoop PacketHeader 源码
haddop PacketHeader 代码
文件路径：/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/PacketHeader.java
/**
* 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.protocol.datatransfer;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.PacketHeaderProto;
import org.apache.hadoop.hdfs.util.ByteBufferOutputStream;
import org.apache.hadoop.util.Preconditions;
import org.apache.hadoop.thirdparty.com.google.common.primitives.Shorts;
import org.apache.hadoop.thirdparty.com.google.common.primitives.Ints;
import org.apache.hadoop.thirdparty.protobuf.InvalidProtocolBufferException;
/**
* Header data for each packet that goes through the read/write pipelines.
* Includes all of the information about the packet, excluding checksums and
* actual data.
*
* This data includes:
* - the offset in bytes into the HDFS block of the data in this packet
* - the sequence number of this packet in the pipeline
* - whether or not this is the last packet in the pipeline
* - the length of the data in this packet
* - whether or not this packet should be synced by the DNs.
*
* When serialized, this header is written out as a protocol buffer, preceded
* by a 4-byte integer representing the full packet length, and a 2-byte short
* representing the header length.
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class PacketHeader {
private static final int MAX_PROTO_SIZE = PacketHeaderProto.newBuilder()
.setOffsetInBlock(0)
.setSeqno(0)
.setLastPacketInBlock(false)
.setDataLen(0)
.setSyncBlock(false)
.build().getSerializedSize();
public static final int PKT_LENGTHS_LEN =
Ints.BYTES + Shorts.BYTES;
public static final int PKT_MAX_HEADER_LEN =
PKT_LENGTHS_LEN + MAX_PROTO_SIZE;
private int packetLen;
private PacketHeaderProto proto;
public PacketHeader() {
}
public PacketHeader(int packetLen, long offsetInBlock, long seqno,
boolean lastPacketInBlock, int dataLen, boolean syncBlock) {
this.packetLen = packetLen;
Preconditions.checkArgument(packetLen >= Ints.BYTES,
"packet len %s should always be at least 4 bytes",
packetLen);
PacketHeaderProto.Builder builder = PacketHeaderProto.newBuilder()
.setOffsetInBlock(offsetInBlock)
.setSeqno(seqno)
.setLastPacketInBlock(lastPacketInBlock)
.setDataLen(dataLen);
if (syncBlock) {
// Only set syncBlock if it is specified.
// This is wire-incompatible with Hadoop 2.0.0-alpha due to HDFS-3721
// because it changes the length of the packet header, and BlockReceiver
// in that version did not support variable-length headers.
builder.setSyncBlock(true);
}
proto = builder.build();
}
public int getDataLen() {
return proto.getDataLen();
}
public boolean isLastPacketInBlock() {
return proto.getLastPacketInBlock();
}
public long getSeqno() {
return proto.getSeqno();
}
public long getOffsetInBlock() {
return proto.getOffsetInBlock();
}
public int getPacketLen() {
return packetLen;
}
public boolean getSyncBlock() {
return proto.getSyncBlock();
}
@Override
public String toString() {
return "PacketHeader with packetLen=" + packetLen +
" header data: " +
proto.toString();
}
public void setFieldsFromData(
int packetLen, byte[] headerData) throws InvalidProtocolBufferException {
this.packetLen = packetLen;
proto = PacketHeaderProto.parseFrom(headerData);
}
public void readFields(ByteBuffer buf) throws IOException {
packetLen = buf.getInt();
short protoLen = buf.getShort();
byte[] data = new byte[protoLen];
buf.get(data);
proto = PacketHeaderProto.parseFrom(data);
}
public void readFields(DataInputStream in) throws IOException {
this.packetLen = in.readInt();
short protoLen = in.readShort();
byte[] data = new byte[protoLen];
in.readFully(data);
proto = PacketHeaderProto.parseFrom(data);
}
/**
* @return the number of bytes necessary to write out this header,
* including the length-prefixing of the payload and header
*/
public int getSerializedSize() {
return PKT_LENGTHS_LEN + proto.getSerializedSize();
}
/**
* Write the header into the buffer.
* This requires that PKT_HEADER_LEN bytes are available.
*/
public void putInBuffer(final ByteBuffer buf) {
assert proto.getSerializedSize() <= MAX_PROTO_SIZE
: "Expected " + (MAX_PROTO_SIZE) + " got: " + proto.getSerializedSize();
try {
buf.putInt(packetLen);
buf.putShort((short) proto.getSerializedSize());
proto.writeTo(new ByteBufferOutputStream(buf));
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public void write(DataOutputStream out) throws IOException {
assert proto.getSerializedSize() <= MAX_PROTO_SIZE
: "Expected " + (MAX_PROTO_SIZE) + " got: " + proto.getSerializedSize();
out.writeInt(packetLen);
out.writeShort(proto.getSerializedSize());
proto.writeTo(out);
}
public byte[] getBytes() {
ByteBuffer buf = ByteBuffer.allocate(getSerializedSize());
putInBuffer(buf);
return buf.array();
}
/**
* Perform a sanity check on the packet, returning true if it is sane.
* @param lastSeqNo the previous sequence number received - we expect the
* current sequence number to be larger by 1.
*/
public boolean sanityCheck(long lastSeqNo) {
// We should only have a non-positive data length for the last packet
if (proto.getDataLen() <= 0 && !proto.getLastPacketInBlock()) return false;
// The last packet should not contain data
if (proto.getLastPacketInBlock() && proto.getDataLen() != 0) return false;
// Seqnos should always increase by 1 with each packet received
return proto.getSeqno() == lastSeqNo + 1;
}
@Override
public boolean equals(Object o) {
if (!(o instanceof PacketHeader)) return false;
PacketHeader other = (PacketHeader)o;
return this.proto.equals(other.proto);
}
@Override
public int hashCode() {
return (int)proto.getSeqno();
}
}
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