org.apache.hadoop.hdfs.server.namenode
Class NameNode.NameNodeHAContext

java.lang.Object
  org.apache.hadoop.hdfs.server.namenode.NameNode.NameNodeHAContext

All Implemented Interfaces:

org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Enclosing class:

org.apache.hadoop.hdfs.server.namenode.NameNode

protected class NameNode.NameNodeHAContext
extends Object
implements org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Class used to expose NameNode as context to HAState

Constructor Summary

protected

NameNode.NameNodeHAContext()

Method Summary

boolean	allowStaleReads()
void	checkOperation(NameNode.OperationCategory op) Check if an operation of given category is allowed
org.apache.hadoop.hdfs.server.namenode.ha.HAState	getState() Get the state from the context
void	prepareToStopStandbyServices() Prepare to exit the standby state
void	setState(org.apache.hadoop.hdfs.server.namenode.ha.HAState s) Set the state of the context to given state
void	startActiveServices() Start the services required in active state
void	startStandbyServices() Start the services required in standby state
void	stopActiveServices() Stop the services when exiting active state
void	stopStandbyServices() Stop the services when exiting standby state
void	writeLock() Take a write-lock on the underlying namesystem so that no concurrent state transitions or edits can be made.
void	writeUnlock() Unlock the lock taken by HAContext.writeLock()

Methods inherited from class java.lang.Object

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

Constructor Detail

NameNode.NameNodeHAContext

protected NameNode.NameNodeHAContext()

Method Detail

setState

public void setState(org.apache.hadoop.hdfs.server.namenode.ha.HAState s)

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Set the state of the context to given state

Specified by:

setState in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

getState

public org.apache.hadoop.hdfs.server.namenode.ha.HAState getState()

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Get the state from the context

Specified by:

getState in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

startActiveServices

public void startActiveServices()
                         throws IOException

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Start the services required in active state

Specified by:

startActiveServices in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Throws:

IOException

stopActiveServices

public void stopActiveServices()
                        throws IOException

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Stop the services when exiting active state

Specified by:

stopActiveServices in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Throws:

IOException

startStandbyServices

public void startStandbyServices()
                          throws IOException

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Start the services required in standby state

Specified by:

startStandbyServices in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Throws:

IOException

prepareToStopStandbyServices

public void prepareToStopStandbyServices()
                                  throws org.apache.hadoop.ha.ServiceFailedException

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Prepare to exit the standby state

Specified by:

prepareToStopStandbyServices in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Throws:

org.apache.hadoop.ha.ServiceFailedException

stopStandbyServices

public void stopStandbyServices()
                         throws IOException

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Stop the services when exiting standby state

Specified by:

stopStandbyServices in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Throws:

IOException

writeLock

public void writeLock()

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Take a write-lock on the underlying namesystem so that no concurrent state transitions or edits can be made.

Specified by:

writeLock in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

writeUnlock

public void writeUnlock()

Description copied from interface: org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Unlock the lock taken by HAContext.writeLock()

Specified by:

writeUnlock in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

checkOperation

public void checkOperation(NameNode.OperationCategory op)
                    throws org.apache.hadoop.ipc.StandbyException

Check if an operation of given category is allowed

Specified by:

checkOperation in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Throws:

org.apache.hadoop.ipc.StandbyException

allowStaleReads

public boolean allowStaleReads()

Specified by:

allowStaleReads in interface org.apache.hadoop.hdfs.server.namenode.ha.HAContext

Returns:

true if the node should allow stale reads (ie reads while the namespace is not up to date)