Package org.apache.hadoop.hdfs.protocol.datatransfer

Class PacketHeader

java.lang.Object

org.apache.hadoop.hdfs.protocol.datatransfer.PacketHeader

@Private
@Evolving
public class PacketHeader
extends java.lang.Object

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.

Field Summary

Fields

Modifier and Type	Field	Description
static int	PKT_LENGTHS_LEN
static int	PKT_MAX_HEADER_LEN

Constructor Summary

Constructors

Constructor	Description
PacketHeader()
PacketHeader(int packetLen, long offsetInBlock, long seqno, boolean lastPacketInBlock, int dataLen, boolean syncBlock)

Method Summary

Modifier and Type	Method	Description
boolean	equals(java.lang.Object o)
byte[]	getBytes()
int	getDataLen()
long	getOffsetInBlock()
int	getPacketLen()
long	getSeqno()
int	getSerializedSize()
boolean	getSyncBlock()
int	hashCode()
boolean	isLastPacketInBlock()
void	putInBuffer(java.nio.ByteBuffer buf)	Write the header into the buffer.
void	readFields(java.io.DataInputStream in)
void	readFields(java.nio.ByteBuffer buf)
boolean	sanityCheck(long lastSeqNo)	Perform a sanity check on the packet, returning true if it is sane.
void	setFieldsFromData(int packetLen, byte[] headerData)
java.lang.String	toString()
void	write(java.io.DataOutputStream out)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

PKT_LENGTHS_LEN

public static final int PKT_LENGTHS_LEN

See Also:

Constant Field Values

PKT_MAX_HEADER_LEN

public static final int PKT_MAX_HEADER_LEN

Constructor Detail

PacketHeader

public PacketHeader()

PacketHeader

public PacketHeader(int packetLen,
                    long offsetInBlock,
                    long seqno,
                    boolean lastPacketInBlock,
                    int dataLen,
                    boolean syncBlock)

Method Detail

getDataLen

public int getDataLen()

isLastPacketInBlock

public boolean isLastPacketInBlock()

getSeqno

public long getSeqno()

getOffsetInBlock

public long getOffsetInBlock()

getPacketLen

public int getPacketLen()

getSyncBlock

public boolean getSyncBlock()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

setFieldsFromData

public void setFieldsFromData(int packetLen,
                              byte[] headerData)
                       throws org.apache.hadoop.thirdparty.protobuf.InvalidProtocolBufferException

Throws:

org.apache.hadoop.thirdparty.protobuf.InvalidProtocolBufferException

readFields

public void readFields(java.nio.ByteBuffer buf)
                throws java.io.IOException

Throws:

java.io.IOException

readFields

public void readFields(java.io.DataInputStream in)
                throws java.io.IOException

Throws:

java.io.IOException

getSerializedSize

public int getSerializedSize()

Returns:

the number of bytes necessary to write out this header, including the length-prefixing of the payload and header

putInBuffer

public void putInBuffer(java.nio.ByteBuffer buf)

Write the header into the buffer. This requires that PKT_HEADER_LEN bytes are available.

write

public void write(java.io.DataOutputStream out)
           throws java.io.IOException

Throws:

java.io.IOException

getBytes

public byte[] getBytes()

sanityCheck

public boolean sanityCheck(long lastSeqNo)

Perform a sanity check on the packet, returning true if it is sane.

Parameters:

lastSeqNo - the previous sequence number received - we expect the current sequence number to be larger by 1.

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object