[jira] [Resolved] (GEODE-4704) GatewaySender batch conflation can incorrectly conflate events causing out of order processing

["Barry Oglesby (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GEODE-4704?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Barry Oglesby resolved GEODE-4704.
----------------------------------
       Resolution: Fixed
    Fix Version/s: 1.5.0

> GatewaySender batch conflation can incorrectly conflate events causing out of order processing
> ----------------------------------------------------------------------------------------------
>
>                 Key: GEODE-4704
>                 URL: https://issues.apache.org/jira/browse/GEODE-4704
>             Project: Geode
>          Issue Type: Bug
>          Components: wan
>            Reporter: Barry Oglesby
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.5.0
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> In the current implementation of \{{AbstractGatewaySenderEventProcessor conflate}} can incorrectly conflate two create events on the same key.
> The else clause of the conflate method (meaning the event is not conflatable) assumes there isn't already a event with the same region, key and operation in the map. It just does a put:
> {noformat}
> ConflationKey key = new ConflationKey(gsEvent.getRegion().getFullPath(), gsEvent.getKeyToConflate(), gsEvent.getOperation());
> conflatedEventsMap.put(key, gsEvent);
> {noformat}
> In certain cases, there could already be a create event on the same region, key and operation in the batch, so the previous one gets replaced by the later once which causes the events to be processed out of order.
> These 4 events:
> {noformat}
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=100;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_13964;shadowKey=27709]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=101;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_14024;shadowKey=27822]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=102;bucketId=24];operation=DESTROY;region=/dataStoreRegion;key=Object_13964;shadowKey=27935]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=104;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_14024;shadowKey=28161]
> {noformat}
> Become these 3 events:
> {noformat}
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=100;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_13964;shadowKey=27709]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=104;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_14024;shadowKey=28161]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=102;bucketId=24];operation=DESTROY;region=/dataStoreRegion;key=Object_13964;shadowKey=27935]
> {noformat}
> Notice the shadowKeys and sequenceIds are out of order after the conflation.
> The fix will be to include the shadow key in hashCode and equals in the case where the event is not conflatable.



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