[jboss-jira] [JBoss JIRA] (JGRP-1851) RSVP: add option to not block caller

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1851?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13006747#comment-13006747 ] 

Bela Ban commented on JGRP-1851:
--------------------------------

Reducing the messages won't work:
* A sends an mcast RSVP beacon
* B creates an mcast RSVP entry, but doesn't send the beacon because A already did
* The RSVP response is received and marks A's and B's entry as done
* If B's message is dropped, we won't continue sending an mcast RSVP beacon for B, so B's message won't get retransmitted

However, we could combine all RSVP beacon mesages to a given dest and send all of the IDs in an _array_ in *one beacon message* rather than in separate beacon messages.

> RSVP: add option to not block caller
> ------------------------------------
>
>                 Key: JGRP-1851
>                 URL: https://issues.jboss.org/browse/JGRP-1851
>             Project: JGroups
>          Issue Type: Feature Request
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>            Priority: Minor
>             Fix For: 3.6
>
>
> In RSVP we have a {{resend_interval}} at which empty messages are sent to trigger retransmission and a {{timeout}} which is the max time a caller will block until all acks have been received.
> In the {{down()}} method, the caller blocks until all acks have been received or a timeout occured. Then the resend task is stopped and the entry removed from the {{ids}} map.
> In some cases, we may want to not block the caller, so that the calling thread returns immediately, but nevertheless perform resending until all acks have been received or the timeout occurred. This is a new property {{block}}. 
> An example of where this is useful is {{RpcDispatcher.callRemoteMethodsWithFuture()}}: here, we want the call to return immediately with a future, and then - later - potentially block on it. However, if we have the RSVP flag set, then sending the message will block in RSVP until all acks have been received. This breaks the semantics of {{callRemoteMethodsWithFuture()}}.
> Another example is async RPCs (mode={{GET_NONE}}); here we'd block if RSVP is set even though we shouldn't.



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