| 1 | package com.hammurapi.common.concurrent; |
| 2 | |
| 3 | import java.util.ArrayList; |
| 4 | import java.util.Collection; |
| 5 | import java.util.concurrent.Callable; |
| 6 | import java.util.concurrent.ExecutionException; |
| 7 | import java.util.concurrent.FutureTask; |
| 8 | |
| 9 | /** |
| 10 | * Future task which cannot block in get() indefinitely. If it is not yet started, |
| 11 | * the task gets executed in the caller thread. |
| 12 | * @author Pavel Vlasov |
| 13 | * |
| 14 | * @param <V> |
| 15 | */ |
| 16 | public class NonBlockingNotifyingFutureTask<V> extends FutureTask<V> implements NotifyingFuture<V> { |
| 17 | |
| 18 | private static class NotifyingCallable<T> implements Callable<T> { |
| 19 | |
| 20 | private Callable<T> master; |
| 21 | |
| 22 | Collection<CallableListener<T>> listeners = new ArrayList<CallableListener<T>>(); |
| 23 | |
| 24 | public NotifyingCallable(Callable<T> master) { |
| 25 | this.master = master; |
| 26 | } |
| 27 | |
| 28 | public T call() throws Exception { |
| 29 | try { |
| 30 | T ret = master.call(); |
| 31 | for (CallableListener<T> listener: copy()) { |
| 32 | listener.onCall(ret); |
| 33 | } |
| 34 | return ret; |
| 35 | } catch (Exception e) { |
| 36 | for (CallableListener<T> listener: copy()) { |
| 37 | listener.onException(e); |
| 38 | } |
| 39 | throw e; |
| 40 | } |
| 41 | } |
| 42 | |
| 43 | private Collection<CallableListener<T>> copy() { |
| 44 | synchronized (listeners) { |
| 45 | return new ArrayList<CallableListener<T>>(listeners); |
| 46 | } |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | private Collection<CallableListener<V>> listeners; |
| 51 | private TaskCounter taskCounter; |
| 52 | |
| 53 | public NonBlockingNotifyingFutureTask(Callable<V> callable, TaskCounter taskCounter) { |
| 54 | super(callable = new NotifyingCallable<V>(callable)); |
| 55 | this.listeners = ((NotifyingCallable<V>) callable).listeners; |
| 56 | if (taskCounter!=null) { |
| 57 | taskCounter.onTaskCreated(this); |
| 58 | } |
| 59 | this.taskCounter = taskCounter; |
| 60 | } |
| 61 | |
| 62 | @Override |
| 63 | public void run() { |
| 64 | try { |
| 65 | super.run(); |
| 66 | } finally { |
| 67 | if (taskCounter!=null) { |
| 68 | taskCounter.onTaskFinished(this); |
| 69 | } |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | @Override |
| 74 | public V get() throws InterruptedException, ExecutionException { |
| 75 | if (!isDone()) { |
| 76 | run(); |
| 77 | } |
| 78 | return super.get(); |
| 79 | } |
| 80 | |
| 81 | public void addListener(CallableListener<V> listener) { |
| 82 | synchronized (listeners) { |
| 83 | listeners.add(listener); |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | public void removeListener(CallableListener<V> listener) { |
| 88 | synchronized (listeners) { |
| 89 | listeners.remove(listener); |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | } |