org.apache.hadoop.yarn.event

Class AsyncDispatcher

java.lang.Object

org.apache.hadoop.service.AbstractService

org.apache.hadoop.yarn.event.AsyncDispatcher

All Implemented Interfaces:

Closeable, AutoCloseable, Service, Dispatcher

@InterfaceAudience.Public
@InterfaceStability.Evolving
public class AsyncDispatcher
extends AbstractService
implements Dispatcher

Dispatches Events in a separate thread. Currently only single thread does that. Potentially there could be multiple channels for each event type class and a thread pool can be used to dispatch the events.

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<Class<? extends Enum>,EventHandler>	eventDispatchers

Fields inherited from interface org.apache.hadoop.yarn.event.Dispatcher

DEFAULT_DISPATCHER_EXIT_ON_ERROR, DISPATCHER_EXIT_ON_ERROR_KEY

Constructor Summary

Constructors

Constructor and Description
AsyncDispatcher()
AsyncDispatcher(BlockingQueue<Event> eventQueue)

Method Summary

Methods

Modifier and Type	Method and Description
protected void	dispatch(Event event)
EventHandler	getEventHandler()
protected boolean	isEventThreadWaiting()
void	register(Class<? extends Enum> eventType, EventHandler handler)
protected void	serviceInit(Configuration conf) All initialization code needed by a service.
protected void	serviceStart() Actions called during the INITED to STARTED transition.
protected void	serviceStop() Actions called during the transition to the STOPPED state.
void	setDrainEventsOnStop()

Methods inherited from class org.apache.hadoop.service.AbstractService

close, getBlockers, getConfig, getFailureCause, getFailureState, getLifecycleHistory, getName, getServiceState, getStartTime, init, isInState, noteFailure, putBlocker, registerGlobalListener, registerServiceListener, removeBlocker, setConfig, start, stop, toString, unregisterGlobalListener, unregisterServiceListener, waitForServiceToStop

Methods inherited from class java.lang.Object

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

Field Detail

eventDispatchers

protected final Map<Class<? extends Enum>,EventHandler> eventDispatchers

Constructor Detail

AsyncDispatcher

public AsyncDispatcher()

AsyncDispatcher

public AsyncDispatcher(BlockingQueue<Event> eventQueue)

Method Detail

serviceInit

protected void serviceInit(Configuration conf)
                    throws Exception

Description copied from class: AbstractService

All initialization code needed by a service. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.init(Configuration) prevents re-entrancy. The base implementation checks to see if the subclass has created a new configuration instance, and if so, updates the base class value

Overrides:

serviceInit in class AbstractService

Parameters:

conf - configuration

Throws:

Exception - on a failure -these will be caught, possibly wrapped, and wil; trigger a service stop

serviceStart

protected void serviceStart()
                     throws Exception

Description copied from class: AbstractService

Actions called during the INITED to STARTED transition. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.start() prevents re-entrancy.

Overrides:

serviceStart in class AbstractService

Throws:

Exception - if needed -these will be caught, wrapped, and trigger a service stop

setDrainEventsOnStop

public void setDrainEventsOnStop()

serviceStop

protected void serviceStop()
                    throws Exception

Description copied from class: AbstractService

Actions called during the transition to the STOPPED state. This method will only ever be called once during the lifecycle of a specific service instance. Implementations do not need to be synchronized as the logic in AbstractService.stop() prevents re-entrancy. Implementations MUST write this to be robust against failures, including checks for null references -and for the first failure to not stop other attempts to shut down parts of the service.

Overrides:

serviceStop in class AbstractService

Throws:

Exception - if needed -these will be caught and logged.

dispatch

protected void dispatch(Event event)

register

public void register(Class<? extends Enum> eventType,
            EventHandler handler)

Specified by:

register in interface Dispatcher

getEventHandler

public EventHandler getEventHandler()

Specified by:

getEventHandler in interface Dispatcher

isEventThreadWaiting

protected boolean isEventThreadWaiting()