/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIESOR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.aries.blueprint.utils.threading.impl;
import java.util.Collections;
import java.util.Queue;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicReference;
public class DiscardableCallable<V> implements Callable<V>, Runnable, Discardable<Runnable>
{
private AtomicReference<Callable<V>> c = new AtomicReference<Callable<V>>();
private Queue<Discardable<Runnable>> _removeFromListOnCall;
public DiscardableCallable(Callable<V> call, Queue<Discardable<Runnable>> _unprocessedWork) {
c.set(call);
_removeFromListOnCall = _unprocessedWork;
_removeFromListOnCall.add(this);
}
private DiscardableCallable(Callable<V> call)
{
c.set(call);
_removeFromListOnCall = new LinkedBlockingQueue<Discardable<Runnable>>();
}
public Runnable discard()
{
_removeFromListOnCall.remove(this);
return new DiscardableCallable<V>(c.getAndSet(null)) ;
}
public V call() throws Exception
{
_removeFromListOnCall.remove(this);
Callable<V> call = c.get();
if (call != null) {
return call.call();
}
throw new CancellationException();
}
public void run()
{
try {
call();
} catch (Exception e) {
}
}
}