AsyncToken.java

/**
 *   GRANITE DATA SERVICES
 *   Copyright (C) 2006-2015 GRANITE DATA SERVICES S.A.S.
 *
 *   This file is part of the Granite Data Services Platform.
 *
 *   Granite Data Services is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   Granite Data Services is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
 *   General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 *   USA, or see <http://www.gnu.org/licenses/>.
 */
package org.granite.client.messaging.channel;

import java.util.ArrayList;
import java.util.List;
import java.util.TimerTask;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeoutException;

import org.granite.client.messaging.ResponseListener;
import org.granite.client.messaging.ResponseListenerDispatcher;
import org.granite.client.messaging.events.CancelledEvent;
import org.granite.client.messaging.events.Event;
import org.granite.client.messaging.events.FailureEvent;
import org.granite.client.messaging.events.FaultEvent;
import org.granite.client.messaging.events.ResultEvent;
import org.granite.client.messaging.events.TimeoutEvent;
import org.granite.client.messaging.messages.RequestMessage;
import org.granite.client.messaging.messages.ResponseMessage;
import org.granite.client.messaging.messages.requests.DisconnectMessage;
import org.granite.client.messaging.messages.responses.FaultMessage;
import org.granite.client.messaging.messages.responses.ResultMessage;
import org.granite.logging.Logger;

/**
 * @author Franck WOLFF
 */
public class AsyncToken extends TimerTask implements ResponseMessageFuture {
	
	private static final Logger log = Logger.getLogger(AsyncToken.class);
	
	private final RequestMessage request;
	private final List<ResponseListener> listeners = new ArrayList<ResponseListener>();
	
	private Event event = null;
	
	private ResponseListener channelListener = null;
	
	public AsyncToken(RequestMessage request) {
		this(request, (ResponseListener[])null);
	}
	
	public AsyncToken(RequestMessage request, ResponseListener listener) {
		this(request, (listener == null ? null : new ResponseListener[]{listener}));
	}
	
	public AsyncToken(RequestMessage request, ResponseListener[] listeners) {
		if (request == null)
			throw new NullPointerException("request cannot be null");
		this.request = request;
		
		if (listeners != null) {
			for (ResponseListener listener : listeners) {
				if (listener == null)
					throw new NullPointerException("listeners cannot contain null values");
				this.listeners.add(listener);
			}
		}
	}

	public String getId() {
		return request.getId();
	}

	public RequestMessage getRequest() {
		return request;
	}
	
	public boolean isDisconnectRequest() {
		return request instanceof DisconnectMessage;
	}
	
	public synchronized Event setChannelListener(ResponseListener channelListener) {
		if (event == null)
			this.channelListener = channelListener;
		return event;
	}

	@Override
	public void run() {
		try {
			// Try to dispatch a TimeoutEvent.
			dispatchTimeout(System.currentTimeMillis());
		}
		catch (Throwable e) {
			log.error(e, "Error while executing token task for request " + request);
		}
	}

	@Override
	public boolean cancel() {
		// Try to dispatch a CancelledEvent.
		return dispatchCancelled();
	}

	@Override
	public ResponseMessage get() throws InterruptedException, ExecutionException, TimeoutException {
		return get(0);
	}

	@Override
	public ResponseMessage get(long timeout) throws InterruptedException, ExecutionException, TimeoutException {
		synchronized (this) {
			if (event == null) {
				try {
					wait(timeout);
				}
				catch (InterruptedException e) {
					if (dispatchCancelled())
						throw e;
				}
			}
		}
		
		return ResponseListenerDispatcher.getResponseMessage(event);
	}

	@Override
	public synchronized boolean isCancelled() {
		return event instanceof CancelledEvent;
	}

	@Override
	public synchronized boolean isDone() {
		return event != null;
	}

	public boolean dispatchResult(ResultMessage result) {
		return dispatch(new ResultEvent(request, result));
	}

	public boolean dispatchFault(FaultMessage fault) {
		return dispatch(new FaultEvent(request, fault));
	}

	public boolean dispatchFailure(Exception e) {
		return dispatch(new FailureEvent(request, e));
	}

	public boolean dispatchTimeout(long millis) {
		return dispatch(new TimeoutEvent(request, millis));
	}

	public boolean dispatchCancelled() {
		return dispatch(new CancelledEvent(request));
	}
	
	private boolean dispatch(Event event) {
		
		// Cancel this TimerTask.
		super.cancel();
		
		synchronized (this) {
			
			// Make sure we didn't dispatch a previous event.
			if (this.event != null)
				return false;
			
			// Create the corresponding event.
			this.event = event;
			
			if (channelListener != null)
				ResponseListenerDispatcher.dispatch(channelListener, event);
			
			// Wake up all threads waiting on the get() method.
			notifyAll();
		}

		// Call all listeners.
		for (ResponseListener listener : listeners)
			ResponseListenerDispatcher.dispatch(listener, event);
		
		// Release references on listeners to help gc
		channelListener = null;
		listeners.clear();
		
		return true;
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == this)
			return true;
		return (obj instanceof AsyncToken) && request.getId().equals(((AsyncToken)obj).request.getId());
	}

	@Override
	public int hashCode() {
		return request.getId().hashCode();
	}

	@Override
	public String toString() {
		return getClass().getName() + " {request=" + request + "}";
	}
}