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dl |
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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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*/ |
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package java.util.concurrent; |
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/** |
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jozart |
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* A {@link CompletionService} that uses a supplied {@link Executor} |
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dl |
1.1 |
* to execute tasks. |
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*/ |
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public class ExecutorCompletionService<V> implements CompletionService<V> { |
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jozart |
1.2 |
private final Executor executor; |
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dl |
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private final LinkedBlockingQueue<Future<V>> cq = |
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new LinkedBlockingQueue<Future<V>>(); |
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/** |
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* FutureTask extension to enqueue upon completion |
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*/ |
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private class QueueingFuture<T> extends FutureTask<T> { |
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QueueingFuture(Callable<T> c) { super(c); } |
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QueueingFuture(Runnable t, T r) { super(t, r); } |
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protected void done() { cq.add((Future<V>)this); } |
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} |
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/** |
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* Creates an ExecutorCompletionService using the supplied |
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* executor for base task execution. Normally, this |
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* executor should be dedicated for use by this service |
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8 @throws NullPointerException if executor is null |
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*/ |
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jozart |
1.2 |
public ExecutorCompletionService(Executor executor) { |
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dl |
1.1 |
if (executor == null) |
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throw new NullPointerException(); |
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this.executor = executor; |
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} |
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/** |
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jozart |
1.2 |
* Return the {@link Executor} used for base |
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dl |
1.1 |
* task execution. This may for example be used to shut |
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* down the service. |
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* @return the executor |
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*/ |
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jozart |
1.2 |
public Executor getExecutor() { |
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dl |
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return executor; |
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} |
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public Future<V> submit(Callable<V> task) { |
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QueueingFuture<V> f = new QueueingFuture<V>(task); |
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executor.execute(f); |
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return f; |
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} |
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public Future<V> submit(Runnable task, V result) { |
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QueueingFuture<V> f = new QueueingFuture<V>(task, result); |
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executor.execute(f); |
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return f; |
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} |
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public Future<V> take() throws InterruptedException { |
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return cq.take(); |
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} |
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public Future<V> poll() { |
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return cq.poll(); |
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} |
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public Future<V> poll(long timeout, TimeUnit unit) throws InterruptedException { |
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return cq.poll(timeout, unit); |
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} |
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} |
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