org.eclipse.jdt.debug/jdi/org/eclipse/jdi/internal/event/EventQueueImpl.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdi.internal.event;


import java.io.IOException;

import org.eclipse.jdi.TimeoutException;
import org.eclipse.jdi.internal.MirrorImpl;
import org.eclipse.jdi.internal.VirtualMachineImpl;
import org.eclipse.jdi.internal.connect.PacketReceiveManager;
import org.eclipse.jdi.internal.jdwp.JdwpCommandPacket;
import org.eclipse.jdi.internal.request.RequestID;

import com.sun.jdi.VMDisconnectedException;
import com.sun.jdi.event.EventQueue;
import com.sun.jdi.event.EventSet;

/**
 * this class implements the corresponding interfaces
 * declared by the JDI specification. See the com.sun.jdi package
 * for more information.
 *
 */
public class EventQueueImpl extends MirrorImpl implements EventQueue {
	/** Flag used to see if a VMDisconnectEvent has already been generated. */
	private boolean genereatedVMDisconnectEvent = false;
	
	/**
	 * Creates new EventQueueImpl.
	 */
	public EventQueueImpl(VirtualMachineImpl vmImpl) {
		super("EventQueue", vmImpl); //$NON-NLS-1$
	}

	/*
	 * @return Returns next EventSet from Virtual Machine.
	 */
	public EventSet remove() throws InterruptedException {
		return remove(PacketReceiveManager.TIMEOUT_INFINITE);
	}

	/*
	 * @return Returns next EventSet from Virtual Machine, returns null if times out.
	 */
	public EventSet remove(long timeout) throws InterruptedException {
		// Return a received EventSet or null if no EventSet is received in time.
		// Note that handledJdwpEventSet() is not don in a 'finally' clause because
		// it must also be done when an 'empty' set is read (i.e. a set composed of internal
		// events only).
	 	try {
	 		// We remove elements from event sets that are generated from inside, therefore the set may become empty.
	 		EventSetImpl set;
	 		do {
	 			JdwpCommandPacket packet = getCommandVM(JdwpCommandPacket.E_COMPOSITE, timeout);
	 			initJdwpEventSet(packet);
	 			set = EventSetImpl.read(this, packet.dataInStream());
				handledJdwpEventSet();
	 		} while (set.isEmpty());
	 		return set;
		} catch (TimeoutException e) {
			// Timeout in getCommand, JDI spec says return null.
			handledJdwpEventSet();
			return null;
		} catch (IOException e) {
			// This means the already received data is invalid.
			handledJdwpEventSet();
			defaultIOExceptionHandler(e);
			return null;
		} catch(VMDisconnectedException e) {
			// JDI spec says that a VMDisconnectedException must always be preceeded by a VMDisconnectEvent.
			handledJdwpEventSet();
			if (!genereatedVMDisconnectEvent) {
				genereatedVMDisconnectEvent = true;
				return new EventSetImpl(virtualMachineImpl(), new VMDisconnectEventImpl(virtualMachineImpl(), RequestID.nullID));
			} 
			throw e;
	 	}
	}
}