[jboss-jira] [JBoss JIRA] (JGRP-1545) UNICAST2: message sent before channel is connected leads to exception

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1545?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12737759#comment-12737759 ] 

Bela Ban commented on JGRP-1545:
--------------------------------

Re my comment at 10:43am: this won't work as we need some unicasts to pass, e.g. a JOIN-RSP needs to pass, or else a new joiner will never even get the BECOME-SERVER event and thus flush the queued messages received before BECOME-SERVER was received !

A possible solution might be:
- Before starting the socket listener (UDP.start() triggered by JChannel._preConnext(), we set a variable 'connecting' to true
- Any message sent when state=connecting is queued
- When transitioning from connecting to connected, we flush that queue
- When transitioning from connecting to open (connect() failed) or closed, we trash the queue's contents

                
> UNICAST2: message sent before channel is connected leads to exception
> ---------------------------------------------------------------------
>
>                 Key: JGRP-1545
>                 URL: https://issues.jboss.org/browse/JGRP-1545
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 3.3
>
>
> When a *unicast* request is received before the first view is received (which sets the channel to connected), and a response to the request is sent, then the response sending throws an exception as the channel hasn't yet been connected (see stack trace below).
> Reason:
> What happens when a channel is created is:
> - JChannel.connect() is called by the user
> - As part of this, start() is called in every protocol
> - UDP.start() creates the sockets and starts the socket listener which will receive messages from now on and pass them up
> - Connect() now sends a JOIN request to the coordinator and receives the JOIN response or become singleton member
> - In either case, a new view is installed, which sets the channel to connected
> If, between starting the socket listener and setting the channel to connected, a *unicast* message is received, and it sends a response then you'll get the behavior below.
> In NAKACK2, this doesn't happen, as all messages received in the same time frame are queued and replayed when the channel becomes connected.
> I could implement the same behavior for UNICAST2, but I'd like to know more about how you got into this situation. What were the steps executed ?
> The only way this could happen I can think of is that the coordinator sent a unicast message to P right after it sent the JOIN response to P, e.g. in the view change which includes P. Does this happen in Infinispan code ?
> {quote}
> 13:29:45,467 ERROR (OOB-1,ISPN,NodeB-50197:) [UNICAST2] couldn't deliver OOB message [dst: NodeB-50197, src: NodeA-40526 (3 headers), size=118 bytes, flags=OOB|DONT_BUNDLE]
> java.lang.IllegalStateException: channel is not connected
>     at org.jgroups.blocks.MessageDispatcher$ProtocolAdapter.down(MessageDispatcher.java:621)
>     at org.jgroups.blocks.RequestCorrelator.handleRequest(RequestCorrelator.java:535)
>     at org.jgroups.blocks.RequestCorrelator.receiveMessage(RequestCorrelator.java:390)
>     at org.jgroups.blocks.RequestCorrelator.receive(RequestCorrelator.java:248)
>     at org.jgroups.blocks.MessageDispatcher$ProtocolAdapter.up(MessageDispatcher.java:604)
>     at org.jgroups.JChannel.up(JChannel.java:688)
>     at org.jgroups.stack.ProtocolStack.up(ProtocolStack.java:1020)
>     at org.jgroups.protocols.FRAG2.up(FRAG2.java:181)
>     at org.jgroups.protocols.FC.up(FC.java:479)
>     at org.jgroups.protocols.pbcast.GMS.up(GMS.java:896)
>     at org.jgroups.protocols.pbcast.STABLE.up(STABLE.java:244)
>     at org.jgroups.protocols.UNICAST2.handleDataReceived(UNICAST2.java:736)
>     at org.jgroups.protocols.UNICAST2.up(UNICAST2.java:414)
>     at org.jgroups.protocols.pbcast.NAKACK2.up(NAKACK2.java:606)
>     at org.jgroups.protocols.MERGE2.up(MERGE2.java:205)
>     at org.jgroups.protocols.Discovery.up(Discovery.java:359)
>     at org.jgroups.protocols.TP.passMessageUp(TP.java:1294)
>     at org.jgroups.protocols.TP$IncomingPacket.handleMyMessage(TP.java:1857)
>     at org.jgroups.protocols.TP$IncomingPacket.run(TP.java:1830)
>     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
>     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
>     at java.lang.Thread.run(Thread.java:722)
> {quote}

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