org.apache.spark.util

Class AsynchronousListenerBus<L,E>

Object

org.apache.spark.util.AsynchronousListenerBus<L,E>

All Implemented Interfaces:

Logging, ListenerBus<L,E>

Direct Known Subclasses:

LiveListenerBus, StreamingListenerBus

public abstract class AsynchronousListenerBus<L,E>
extends Object
implements ListenerBus<L,E>

Asynchronously passes events to registered listeners.

Until start() is called, all posted events are only buffered. Only after this listener bus has started will events be actually propagated to all attached listeners. This listener bus is stopped when stop() is called, and it will drop further events after stopping.

Constructor Summary

Constructors

Constructor and Description
AsynchronousListenerBus(String name)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	listenerThreadIsAlive() For testing only.
abstract void	onDropEvent(E event) If the event queue exceeds its capacity, the new events will be dropped.
void	post(E event)
void	start() Start sending events to attached listeners.
void	stop() Stop the listener bus.
boolean	waitUntilEmpty(int timeoutMillis) For testing only.

Methods inherited from class Object

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

Methods inherited from interface org.apache.spark.util.ListenerBus

addListener, listeners, onPostEvent, postToAll

Methods inherited from interface org.apache.spark.Logging

initializeIfNecessary, initializeLogging, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning

Constructor Detail

AsynchronousListenerBus

public AsynchronousListenerBus(String name)

Method Detail

start

public void start()

Start sending events to attached listeners.

This first sends out all buffered events posted before this listener bus has started, then listens for any additional events asynchronously while the listener bus is still running. This should only be called once.

post

public void post(E event)

waitUntilEmpty

public boolean waitUntilEmpty(int timeoutMillis)

For testing only. Wait until there are no more events in the queue, or until the specified time has elapsed. Return true if the queue has emptied and false is the specified time elapsed before the queue emptied.

listenerThreadIsAlive

public boolean listenerThreadIsAlive()

For testing only. Return whether the listener daemon thread is still alive.

stop

public void stop()

Stop the listener bus. It will wait until the queued events have been processed, but drop the new events after stopping.

onDropEvent

public abstract void onDropEvent(E event)

If the event queue exceeds its capacity, the new events will be dropped. The subclasses will be notified with the dropped events.

Note: onDropEvent can be called in any thread.