/*
* Quasar: lightweight threads and actors for the JVM.
* Copyright (C) 2013, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.strands.channels;
import co.paralleluniverse.fibers.SuspendExecution;
import co.paralleluniverse.strands.Condition;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* An adapter that turns a DelayedVal into a ReceivePort that receives the DelayedVal's value and then closes.
*
* @author pron
*/
public class DelayedValChannel<V> implements ReceivePort<V>, Selectable<V> {
private final DelayedVal<V> dv;
private final AtomicBoolean closed = new AtomicBoolean();
public DelayedValChannel(DelayedVal<V> val) {
this.dv = val;
}
@Override
public V receive() throws SuspendExecution, InterruptedException {
if (closed.get())
return null;
final V v = dv.get();
close();
return v;
}
@Override
public V tryReceive() {
if (closed.get())
return null;
if (!dv.isDone())
return null;
final V v = dv.getValue();
close();
return v;
}
@Override
public V receive(long timeout, TimeUnit unit) throws SuspendExecution, InterruptedException {
if (closed.get())
return null;
final V v;
try {
v = dv.get(timeout, unit);
close();
return v;
} catch (TimeoutException ex) {
return null;
}
}
@Override
public void close() {
closed.set(true);
}
@Override
public boolean isClosed() {
return closed.get();
}
@Override
public Object register(SelectAction<V> action) {
if (action.isData())
throw new UnsupportedOperationException("Send is not supported by DelayedValChanel");
Condition sync = dv.getSync();
if (sync == null) {
if (!action.lease())
return null;
action.setItem(dv.getValue());
action.won();
return null;
}
sync.register();
return action;
}
@Override
public boolean tryNow(Object token) {
if(!dv.isDone())
return false;
SelectAction<V> action = (SelectAction<V>)token;
if (!action.lease())
return false;
action.setItem(dv.getValue());
action.won();
return true;
}
@Override
public void unregister(Object token) {
if (token == null)
return;
Condition sync = dv.getSync();
if (sync != null)
sync.unregister();
}
}