/**
* Performs a selective receive. This method blocks (but for no longer than the given timeout)
* until a message that is {@link MessageProcessor#process(java.lang.Object) selected} by the
* given {@link MessageProcessor} is available in the mailbox, and returns the value returned by
* {@link MessageProcessor#process(java.lang.Object) MessageProcessor.process}. If the given
* timeout expires, this method returns {@code null}.
*
* <p>Messages that are not selected, are temporarily skipped. They will remain in the mailbox
* until another call to receive (selective or non-selective) retrieves them.
*
* @param <T> The type of the returned value
* @param timeout the duration to wait for a matching message to arrive.
* @param unit timeout's time unit.
* @param proc performs the selection.
* @return The non-null value returned by {@link MessageProcessor#process(java.lang.Object)
* MessageProcessor.process}, or {@code null} if the timeout expired.
* @throws InterruptedException
*/
public final <T> T receive(long timeout, TimeUnit unit, MessageProcessor<? super Message, T> proc)
throws TimeoutException, SuspendExecution, InterruptedException {
assert Actor.currentActor() == null || Actor.currentActor() == actor;
final Mailbox<Object> mailbox = actor.mailbox();
actor.checkThrownIn0();
mailbox.maybeSetCurrentStrandAsOwner();
final long start = timeout > 0 ? System.nanoTime() : 0;
long now;
long left = unit != null ? unit.toNanos(timeout) : 0;
final long deadline = start + left;
actor.monitorResetSkippedMessages();
QueueIterator<Object> it = mailbox.queue().iterator();
for (int i = 0; ; i++) {
if (actor.flightRecorder != null)
actor.record(
1,
"SelctiveReceiveHelper",
"receive",
"%s waiting for a message. %s",
this,
timeout > 0
? "millis left: " + TimeUnit.MILLISECONDS.convert(left, TimeUnit.NANOSECONDS)
: "");
mailbox.lock();
if (it.hasNext()) {
final Object m = it.next();
mailbox.unlock();
if (m == currentMessage) {
it.remove();
continue;
}
actor.record(1, "SelctiveReceiveHelper", "receive", "Received %s <- %s", this, m);
actor.monitorAddMessage();
if (m instanceof LifecycleMessage) {
it.remove();
handleLifecycleMessage((LifecycleMessage) m);
} else {
final Message msg = (Message) m;
currentMessage = msg;
try {
T res = proc.process(msg);
if (res != null) {
if (it.value()
== msg) // another call to receive from within the processor may have deleted msg
it.remove();
return res;
}
} catch (Exception e) {
if (it.value()
== msg) // another call to receive from within the processor may have deleted msg
it.remove();
throw e;
} finally {
currentMessage = null;
}
actor.record(1, "SelctiveReceiveHelper", "receive", "%s skipped %s", this, m);
actor.monitorSkippedMessage();
}
} else {
try {
if (unit == null) mailbox.await(i);
else if (timeout > 0) {
mailbox.await(i, left, TimeUnit.NANOSECONDS);
now = System.nanoTime();
left = deadline - now;
if (left <= 0) {
actor.record(1, "Actor", "receive", "%s timed out.", this);
throw new TimeoutException();
}
} else {
return null;
}
} finally {
mailbox.unlock();
}
}
}
}
