[jboss-jira] [JBoss JIRA] Updated: (JBMESSAGING-247) Race condition - out of order delivery

[Ovidiu Feodorov (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBMESSAGING-247?page=all ]

Ovidiu Feodorov updated JBMESSAGING-247:
----------------------------------------

    Fix Version/s: 1.2.0.Alpha1
                       (was: 1.2)

> Race condition - out of order delivery
> --------------------------------------
>
>                 Key: JBMESSAGING-247
>                 URL: http://jira.jboss.com/jira/browse/JBMESSAGING-247
>             Project: JBoss Messaging
>          Issue Type: Bug
>            Reporter: Tim Fox
>         Assigned To: Tim Fox
>             Fix For: 1.2.0.Alpha1
>
>
> This race condition has never actually been observed, but should be possible:
> Out of sequence cancel.
> Consider the following.
> 1. client does a recieve(1000).
> 2. This causes serverconsumerdelegate.activate() to be called.
> 3. The client times out.
> 4. The serverconsumerdelegate accepts a message and sends it asynch to the client consumer.
> 5. serverconsumerdelegate.deactive() is called (too late though)
> 6. The message arrives at the messagecallbackhandler
> 7. The message is not accepted since the consumer is not receiving
> 8. ServerConsumerdelegate.cancel() is called.
> 9. client does another receive(1000)
> 10. This causes serverconsumerdelegate.activate() to be called.
> 11. A message is accepted and sent asynch to the client.
> 12. The cancel is processed. And the message put back on the queue
> 13. Wrong message is received at client!!
> Race condition in asynchronous cancelling of message:
> If consumer is waiting on receive(timeout) then times out, then just after that a message is received, it gets cancelled.
> But the cancellation could happen *after* the next receive occurs giving messages out of sequence.
> Solution to this is as follows:
> If a message arrives late, instead of cancelling then asynchonrously, a flag is set and the message id of the missed message is recorded
> in the message callback handler, then when the next receive occurs, this flag is checked and if true, then a cancel is done *before*
> the next receive.

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