Package org.apache.hadoop.hdfs

Class DFSPacket

java.lang.Object

org.apache.hadoop.hdfs.DFSPacket

@Private
public class DFSPacket
extends java.lang.Object

DFSPacket is used by DataStreamer and DFSOutputStream. DFSOutputStream generates packets and then ask DatStreamer to send them to datanodes.

Field Summary

Fields

Modifier and Type	Field	Description
static long	HEART_BEAT_SEQNO

Constructor Summary

Constructors

Constructor	Description
DFSPacket(byte[] buf, int chunksPerPkt, long offsetInBlock, long seqno, int checksumSize, boolean lastPacketInBlock)	Create a new packet.

Method Summary

Modifier and Type	Method	Description
void	addTraceParent(org.apache.hadoop.tracing.Span span)	Add a trace parent span for this packet.
void	addTraceParent(org.apache.hadoop.tracing.SpanContext ctx)
org.apache.hadoop.tracing.Span	getSpan()
org.apache.hadoop.tracing.SpanContext[]	getTraceParents()	Get the trace parent spans for this packet.
void	setSpan(org.apache.hadoop.tracing.Span span)
java.lang.String	toString()
void	writeChecksum(byte[] inarray, int off, int len)	Write checksums to this packet
void	writeData(java.nio.ByteBuffer inBuffer, int len)
void	writeTo(java.io.DataOutputStream stm)	Write the full packet, including the header, to the given output stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

HEART_BEAT_SEQNO

public static final long HEART_BEAT_SEQNO

See Also:

Constant Field Values

Constructor Detail

DFSPacket

public DFSPacket(byte[] buf,
                 int chunksPerPkt,
                 long offsetInBlock,
                 long seqno,
                 int checksumSize,
                 boolean lastPacketInBlock)

Create a new packet.

Parameters:

buf - the buffer storing data and checksums

chunksPerPkt - maximum number of chunks per packet.

offsetInBlock - offset in bytes into the HDFS block.

seqno - the sequence number of this packet

checksumSize - the size of checksum

lastPacketInBlock - if this is the last packet

Method Detail

writeData

public void writeData(java.nio.ByteBuffer inBuffer,
                      int len)
               throws java.nio.channels.ClosedChannelException

Throws:

java.nio.channels.ClosedChannelException

writeChecksum

public void writeChecksum(byte[] inarray,
                          int off,
                          int len)
                   throws java.nio.channels.ClosedChannelException

Write checksums to this packet

Parameters:

inarray - input array of checksums

off - the offset of checksums to write

len - the length of checksums to write

Throws:

java.nio.channels.ClosedChannelException

writeTo

public void writeTo(java.io.DataOutputStream stm)
             throws java.io.IOException

Write the full packet, including the header, to the given output stream.

Throws:

java.io.IOException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

addTraceParent

public void addTraceParent(org.apache.hadoop.tracing.Span span)

Add a trace parent span for this packet.

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.

Protected by the DFSOutputStream dataQueue lock.

addTraceParent

public void addTraceParent(org.apache.hadoop.tracing.SpanContext ctx)

getTraceParents

public org.apache.hadoop.tracing.SpanContext[] getTraceParents()

Get the trace parent spans for this packet.

Will always be non-null.

Protected by the DFSOutputStream dataQueue lock.

setSpan

public void setSpan(org.apache.hadoop.tracing.Span span)

getSpan

public org.apache.hadoop.tracing.Span getSpan()