Hi Heiko, That actually makes a lot of sense. I keep forgetting that things within an actor happen on a message by message basis. Thanks for the clarification!
Luis On Tuesday, August 19, 2014 10:59:36 PM UTC-7, Heiko Seeberger wrote: > > Luis, > > As an actor only handles one message at a time, the order of `unstashAll` > and `context.become` doesn’t matter at all: Both happen while processing > the current message which means that no other message gets processed until > both methods (and the rest of the current behavior) have been executed. > Then, when the next message is about to get processed, both methods have > already been executed. > > BTW, I have seen many who have been thinking along the same lines ;-) > > Cheers > Heiko > > On 19 Aug 2014, at 19:09, Luis Medina <[email protected] <javascript:>> > wrote: > > Hi all, > > I'm working on implementing retry functionality in one of my actor's that > will retry writing a message to RabbitMQ if the original write fails. This > looks something like this: > > private String retryMessage; > > private void processMessage(String message) { > try { > writer.write(message); > } catch (IOException e) { > LOGGER.warn("Unable to write message to RabbitMQ. Retrying..."); > retryMessage = message; > context().become(retry); > sendTimeout(); > } > } > > private PartialFunction<Object, BoxedUnit> retry = ReceiveBuilder > .match(String.class, message -> stash()) > .match(ReceiveTimeout.class, receiveTimeout -> retryMessage()) > .build(); > > private void sendTimeout() { > long waitTime = getWaitTime(); > > context().setReceiveTimeout(Duration.Undefined()); > context().setReceiveTimeout(Duration.create(waitTime, > TimeUnit.MILLISECONDS)); > } > > private void retryMessage() { > try { > writer.write(retryMessage); > context().setReceiveTimeout(Duration.Undefined()); > context().unbecome(); > unstashAll(); > } catch (IOException e) { > LOGGER.warn("Unable to write message to RabbitMQ. Retrying..."); > sendTimeout(); > } > } > > As you can see, when the write fails, the actor switches to a "retry" > mode. In this retry mode, it will stash any incoming messages that are > meant to be written until it can successfully write the original message > that it failed on. To do a retry, I set a ReceiveTimeout that whose > duration increases exponentially with each failure. When the actor receives > a ReceiveTimeout, it simply tries to write it again. Now the part that I'm > curious about has to do with unstashing all of the messages and unbecoming > its retry mode. > > In the retryMessage() method, if the write is successful, the > ReceiveTimeout will be shut off, the actor will revert back to its original > state, and any messages that were stashed during this time will be > unstashed. In terms of reverting back to its original state and unstashing > messages, is this the right order in which to do this? In all of the > examples that I've seen, I noticed that the unstashAll() always came > before the context().unbecome() which is what I originally had. After > giving it some thought, however, I started to wonder if having this order > would cause me to lose any messages if they arrived in between the > unstashAll() and context().unbecome() operations thus causing them to get > stashed but never becoming unstashed again. This is why I ended up > reversing their order. Is my thinking correct? > > Luis > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > To post to this group, send email to [email protected] > <javascript:>. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > > > -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
