content: /*
   * Copyright (c) 2017, Andreas Fagschlunger. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   *   - Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   *
   *   - Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package at.o2xfs.xfs.service.cmd;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import at.o2xfs.log.Logger;
  import at.o2xfs.log.LoggerFactory;
  import at.o2xfs.xfs.WFSResult;
  import at.o2xfs.xfs.service.events.XfsEventNotification;
  
  /**
   * @author Andreas Fagschlunger
   */
  public class EventQueue implements XfsEventNotification {
  
  	private static final Logger LOG = LoggerFactory.getLogger(EventQueue.class);
  
  	private final Thread dispatchThread;
  
  	private final List<WFSResult> intermediateEvents;
  
  	private final XfsEventNotification eventNotification;
  
  	private WFSResult operationCompleteEvent = null;
  
  	public EventQueue(final XfsEventNotification eventNotification) {
  		if (eventNotification == null) {
  			throw new IllegalArgumentException();
  		}
  		this.eventNotification = eventNotification;
  		intermediateEvents = new ArrayList<WFSResult>();
  		dispatchThread = new Thread(new Runnable() {
  
  			@Override
  			public void run() {
  				waitAndDispatch();
  			}
  		});
  		dispatchThread.start();
  	}
  
  	private void waitAndDispatch() {
  		final String method = "waitAndDispatch()";
  		try {
  			while (!dispatchThread.isInterrupted()) {
  				WFSResult intermediateEvent = null;
  				synchronized (this) {
  					while (intermediateEvents.isEmpty()
  							&& operationCompleteEvent == null) {
  						if (LOG.isDebugEnabled()) {
  							LOG.debug(method, "Waiting ...");
  						}
  						wait();
  					}
  					if (!intermediateEvents.isEmpty()) {
  						intermediateEvent = intermediateEvents.remove(0);
  					}
  				}
  				if (intermediateEvent != null) {
  					eventNotification.fireIntermediateEvent(intermediateEvent);
  				} else {
  					eventNotification
  							.fireOperationCompleteEvent(operationCompleteEvent);
  					return;
  				}
  			}
  		} catch (final InterruptedException e) {
  			if (LOG.isErrorEnabled()) {
  				LOG.error(method, "Interrupted while waiting", e);
  			}
  		}
  	}
  
  	@Override
  	public void fireIntermediateEvent(final WFSResult intermediateEvent) {
  		synchronized (this) {
  			intermediateEvents.add(intermediateEvent);
  			notifyAll();
  		}
  	}
  
  	@Override
  	public void fireOperationCompleteEvent(final WFSResult ocEvent) {
  		synchronized (this) {
  			operationCompleteEvent = ocEvent;
  			notifyAll();
  		}
  	}
  }