Package org.apache.hadoop.service.launcher

Class ServiceShutdownHook

java.lang.Object

org.apache.hadoop.service.launcher.ServiceShutdownHook

All Implemented Interfaces:

Runnable

@Private
@Unstable
public class ServiceShutdownHook
extends Object
implements Runnable

JVM Shutdown hook for Service which will stop the Service gracefully in case of JVM shutdown. This hook uses a weak reference to the service, and when shut down, calls Service.stop() if the reference is valid.

Constructor Summary

Constructors

Constructor	Description
ServiceShutdownHook(Service service)	Create an instance.

Method Summary

Modifier and Type	Method	Description
void	register(int priority)	Register the service for shutdown with Hadoop's ShutdownHookManager.
void	run()	Shutdown handler.
protected boolean	shutdown()	Shutdown operation.
void	unregister()	Unregister the hook.

Methods inherited from class java.lang.Object

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

Constructor Details

ServiceShutdownHook

public ServiceShutdownHook(Service service)

Create an instance.

Parameters:

service - the service

Method Details

register

public void register(int priority)

Register the service for shutdown with Hadoop's ShutdownHookManager.

Parameters:

priority - shutdown hook priority

unregister

public void unregister()

Unregister the hook.

run

public void run()

Shutdown handler. Query the service hook reference -if it is still valid the Service.stop() operation is invoked.

Specified by:

run in interface Runnable

shutdown

protected boolean shutdown()

Shutdown operation.

Subclasses may extend it, but it is primarily made available for testing.

Returns:

true if the service was stopped and no exception was raised.