Improve MessageGroupStoreReaper Algorithms [INT-2754]

[spring-operator]

Gary Russell opened INT-2754 and commented

Currently, the reaper pulls an expired group which is then considered for reaping after acquiring a lock. By the time the lock is acquired, the group could have changed; this means we have to re-fetch the group.

MessageGroupStore currently does not support simply obtaining just a group's lastModified time, so in both cases, the whole group is pulled.

Improvements can be made to this algorithm by adding ```
MessageGroupStore.getLastModified(Object groupId)

Also, the AbstractCorrelatingMessageHandler now supports the LockRegistry. With a global lock implementation of the registry, these reaper changes would support group reaping across a distributed environment.

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Affects: 2.2 M4

Issue Links:

• Add locking strategy to AbstractMessageGroupStore [INT-1117] #5123 Add locking strategy to AbstractMessageGroupStore

[spring-operator]

Artem Bilan commented

After introducing a MessageGroupFactory strategy: https://docs.spring.io/spring-integration/docs/current/reference/html/system-management.html#message-group-factory we don't load the whole group with its messages from the store by default: only metadata.

The AbstractCorrelatingMessageHandler.forceComplete(MessageGroup) now re-fetch the group for its actual data during the lock. See the comment in the source code for more info.

Therefore I treat this ticket as fixed.