/interpreter/tags/at2dist110511/src/edu/vub/at/actors/natives/NATRemoteFarRef.java

  1/**
  2 * AmbientTalk/2 Project
  3 * NATRemoteFarRef.java created on 22-dec-2006 at 11:35:01
  4 * (c) Programming Technology Lab, 2006 - 2007
  5 * Authors: Tom Van Cutsem & Stijn Mostinckx
  6 * 
  7 * Permission is hereby granted, free of charge, to any person
  8 * obtaining a copy of this software and associated documentation
  9 * files (the "Software"), to deal in the Software without
 10 * restriction, including without limitation the rights to use,
 11 * copy, modify, merge, publish, distribute, sublicense, and/or
 12 * sell copies of the Software, and to permit persons to whom the
 13 * Software is furnished to do so, subject to the following
 14 * conditions:
 15 *
 16 * The above copyright notice and this permission notice shall be
 17 * included in all copies or substantial portions of the Software.
 18 *
 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 21 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 23 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 24 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 26 * OTHER DEALINGS IN THE SOFTWARE.
 27 */
 28package edu.vub.at.actors.natives;
 29
 30import edu.vub.at.actors.ATLetter;
 31import edu.vub.at.actors.eventloops.BlockingFuture;
 32import edu.vub.at.actors.id.ATObjectID;
 33import edu.vub.at.eval.Evaluator;
 34import edu.vub.at.exceptions.InterpreterException;
 35import edu.vub.at.exceptions.XTypeMismatch;
 36import edu.vub.at.objects.ATObject;
 37import edu.vub.at.objects.ATTable;
 38import edu.vub.at.objects.ATTypeTag;
 39
 40/**
 41 * Instances of NATRemoteFarRef represent far references to physically remote actors.
 42 * By 'physically remote', we mean in a separate address space.
 43 * 
 44 * @author tvcutsem
 45 */
 46public class NATRemoteFarRef extends NATFarReference {
 47	
 48	/**
 49	 * When a remote far reference is passed on to another virtual machine, the sendLoop
 50	 * is not taken with it. At the remote end, the sendLoop is bound to the 
 51	 * FarReferencesThreadPool of the receiving actor.
 52	 */
 53	private transient final FarReferencesThreadPool sendLoop_;
 54	
 55	/** boolean that keeps track if there is a thread of the FarReferencesThreadPool
 56	 *  currently transmitting a message. It is used to make meta_retract() wait  
 57	 *  for the success/failure of the message currently being sent.
 58	 */
 59    private transient boolean transmitting_;
 60    
 61	public NATRemoteFarRef(ATObjectID objectId, ELActor hostActor, ATTypeTag[] types, boolean isConnected) {
 62		super(objectId, types, hostActor, isConnected);
 63		sendLoop_ = hostActor.getHost().farReferencesThreadPool_; 
 64		transmitting_ = false;
 65	}
 66	
 67	/**
 68	 * Inserts an AmbientTalk message into this far reference's outbox
 69	 * and signals a transmit event to the corresponding FarReferencesThreadPool
 70	 * to schedule its transmission.
 71	 */
 72	protected void transmit(ATLetter letter) throws InterpreterException {
 73		outbox_.addLast(letter);
 74		impl_transmit();
 75	}
 76	
 77	public ATTable meta_retractUnsentMessages() throws InterpreterException {
 78		return sendLoop_.sync_event_retractUnsentMessages(this);
 79	}
 80	
 81	protected synchronized void notifyStateToSendLoop(boolean state){
 82		//if notifying reconnection, start flushing the outbox serially
 83		if (state) { impl_transmit(); }
 84	}
 85	
 86	public NATRemoteFarRef asNativeRemoteFarReference() throws XTypeMismatch { return this;}
 87
 88	/* Following methods are called by a thread within FarReferencesThreadPool */
 89	
 90	public ATObject impl_serve() throws InterpreterException{
 91		synchronized(this) {
 92			if (outbox_.size() > 0 && connected_) {
 93				NATOutboxLetter next = (NATOutboxLetter) outbox_.removeLast();
 94				setTransmitting(true);
 95				return next;
 96			}
 97		}
 98		return Evaluator.getNil();
 99	}
100    
101	// called from a FarReferencesThreadPool#TransmissionEvent 
102	// after successfully sending a message to 
103	// cause the transmission of next message if any.
104	// Also called from ELActor after adding a message in this outbox.
105	public void impl_transmit() {
106		sendLoop_.event_serve(this);
107	}	
108	// called from a FarReferencesThreadPool#TransmissionEvent 
109	// after the message being transmitted failed.
110	public void impl_transmitFailed(ATLetter letter) {
111		disconnected();
112		// add the message back to the outbox.
113		// it cannot happen that this event_transmit is followed by an event_transmit for another message, 
114		// so the order will be preserved.
115		synchronized(this){
116		  outbox_.addFirst(letter);
117		}
118		setTransmitting(false);
119	}
120	
121	public synchronized void setTransmitting(boolean status) {
122		transmitting_ = status;
123	}
124	
125	public synchronized boolean getTransmitting(){
126		return transmitting_;
127	}
128}