Package org.apache.hadoop.hdfs.server.protocol

Class CheckpointCommand

java.lang.Object

org.apache.hadoop.hdfs.server.protocol.ServerCommand

org.apache.hadoop.hdfs.server.protocol.NamenodeCommand

org.apache.hadoop.hdfs.server.protocol.CheckpointCommand

@Private
@Evolving
public class CheckpointCommand
extends NamenodeCommand

Checkpoint command.

Returned to the backup node by the name-node as a reply to the NamenodeProtocol.startCheckpoint(NamenodeRegistration) request.
Contains:

• CheckpointSignature identifying the particular checkpoint
• indicator whether the backup image should be discarded before starting the checkpoint
• indicator whether the image should be transfered back to the name-node upon completion of the checkpoint.

Constructor Summary

Constructors

Constructor	Description
CheckpointCommand()
CheckpointCommand(CheckpointSignature sig, boolean needToReturnImg)

Method Summary

Modifier and Type	Method	Description
CheckpointSignature	getSignature()	Checkpoint signature is used to ensure that nodes are talking about the same checkpoint.
boolean	needToReturnImage()	Indicates whether the new checkpoint image needs to be transfered back to the name-node after the checkpoint is done.

Methods inherited from class org.apache.hadoop.hdfs.server.protocol.ServerCommand

getAction, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

CheckpointCommand

public CheckpointCommand()

CheckpointCommand

public CheckpointCommand(CheckpointSignature sig,
                         boolean needToReturnImg)

Method Detail

getSignature

public CheckpointSignature getSignature()

Checkpoint signature is used to ensure that nodes are talking about the same checkpoint.

needToReturnImage

public boolean needToReturnImage()

Indicates whether the new checkpoint image needs to be transfered back to the name-node after the checkpoint is done.

Returns:

true if the checkpoint should be returned back.