[infinispan-issues] [JBoss JIRA] (ISPN-1541) NotifyingNotifiableFuture's FutureListener can not invoke Future API on FutureListener#futureDone callback

NotifyingNotifiableFuture's FutureListener can not invoke Future API on FutureListener#futureDone callback ---------------------------------------------------------------------------------------------------------- Key: ISPN-1541 URL: https://issues.jboss.org/browse/ISPN-1541 Project: Infinispan Issue Type: Bug Components: RPC Affects Versions: 5.0.1.FINAL, 5.1.0.BETA4 Reporter: Vladimir Blagojevic Assignee: Vladimir Blagojevic Fix For: 5.1.0.CR1 Invoking Future#get from a FutureListener attached to a NotifyingNotifiableFuture passed as a parameter to RpcManager#invokeRemotelyInFuture throws InterruptedException! Sounds more complicated than it really is! In another words, the following code throws InterruptedException {code}NotifyingFutureImpl f = ... f.attachListener(new FutureListener<Object>() { @Override public void futureDone(Future<Object> future) { try { future.get(); } catch (Exception e) { e.printStackTrace(); } } }); CommandsFactory cf = cache1.getAdvancedCache().getComponentRegistry().getComponent(CommandsFactory.class); cache1.getAdvancedCache().getRpcManager().invokeRemotelyInFuture(null, cf.buildPutKeyValueCommand("k","v", -1, -1, null), f); {code} the reason why we get InterruptedException is that we invoke notifyDone which in turn invokes futureDone from the same thread invoking the future's callable. In effect we invoke future#get followed by future#get on the same future instance using *the same thread*! {code} public final void invokeRemotelyInFuture(final Collection<Address> recipients, final ReplicableCommand rpc, final boolean usePriorityQueue, final NotifyingNotifiableFuture<Object> l, final long timeout) { if (trace) log.tracef("%s invoking in future call %s to recipient list %s", t.getAddress(), rpc, recipients); final CountDownLatch futureSet = new CountDownLatch(1); Callable<Object> c = new Callable<Object>() { public Object call() throws Exception { Object result = null; try { result = invokeRemotely(recipients, rpc, true, usePriorityQueue, timeout); } finally { try { futureSet.await(); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } finally { l.notifyDone(); } } return result; } }; l.setNetworkFuture(asyncExecutor.submit(c)); futureSet.countDown(); } {code} The solution is to wait for callable to finish and invoke notifyDone from the other thread. We have two choices here: a) invoke notifyDone from the same thread invoking invokeRemotelyInFuture. This in turn changes invokeRemotelyInFuture to be less async than it should be b) invoke callback on another thread {code} public final void invokeRemotelyInFuture(final Collection<Address> recipients, final ReplicableCommand rpc, final boolean usePriorityQueue, final NotifyingNotifiableFuture<Object> l, final long timeout) { if (trace) log.tracef("%s invoking in future call %s to recipient list %s", t.getAddress(), rpc, recipients); final CountDownLatch callableCompleted = new CountDownLatch(1); Callable<Object> c = new Callable<Object>() { public Object call() throws Exception { Object result = null; try { result = invokeRemotely(recipients, rpc, true, usePriorityQueue, timeout); } finally { callableCompleted.countDown(); } return result; } }; l.setNetworkFuture(asyncExecutor.submit(c)); asyncExecutor.submit(new Runnable() { @Override public void run() { try { callableCompleted.await(); } catch (Exception e) { } finally { l.notifyDone(); } } }); } {code} We can of course, leave things as they are right now but in such case we have to warn the implementer of FutureListener that he/she can not call future.get() from a FutureListener!