de.intarsys.tools.event.DeferredEventDispatcher Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of isrt Show documentation

The basic runtime tools and interfaces for intarsys components.

There is a newer version: 4.11

package de.intarsys.tools.event;

import java.util.ArrayList;
import java.util.List;

/**
 * Pluggable helper object for management and dispatching of events. This
 * utility is quite handsome when you
 * 
 * need to ensure event ordering in multithreaded scenarios
 * need to trigger events that you want to keep out of synchronized code
 * 
 * 
 * Events are forwarded upon "flush" to all listeners in the thread of the
 * caller.
 * 
 */
public class DeferredEventDispatcher implements INotificationListener,
		INotificationSupport {

	final private List events = new ArrayList();

	final private EventDispatcher dispatcher;

	final private Object lock = new Object();

	public DeferredEventDispatcher(EventDispatcher dispatcher) {
		this.dispatcher = dispatcher;
	}

	public DeferredEventDispatcher(Object owner) {
		this.dispatcher = new EventDispatcher(owner);
	}

	public void addNotificationListener(EventType type,
			INotificationListener listener) {
		dispatcher.addNotificationListener(type, listener);
	}

	public void flush() {
		List tempEvents;
		synchronized (lock) {
			tempEvents = new ArrayList(events);
			events.clear();
		}
		for (Event event : tempEvents) {
			dispatcher.handleEvent(event);
		}
	}

	public void handleEvent(Event event) {
		synchronized (lock) {
			events.add(event);
		}
	}

	public boolean hasListener() {
		return dispatcher.hasListener();
	}

	public void removeNotificationListener(EventType type,
			INotificationListener listener) {
		dispatcher.removeNotificationListener(type, listener);
	}
}