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https://issues.apache.org/jira/browse/CAMEL-25515?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Claus Ibsen resolved CAMEL-25515.
---------------------------------
Resolution: Fixed
> camel-jgroups-raft - the consumer's role change events do not handle the
> Learner role
> -------------------------------------------------------------------------------------
>
> Key: CAMEL-25515
> URL: https://issues.apache.org/jira/browse/CAMEL-25515
> Project: Camel
> Issue Type: Bug
> Components: camel-jgroups
> Reporter: Claus Ibsen
> Assignee: Andrea Cosentino
> Priority: Minor
> Fix For: 4.24.0
>
>
> The jgroups-raft consumer with {{enableRoleChangeEvents=true}} does not
> handle the {{Learner}} role.
> {{CamelRoleChangeListener.roleChanged}} only maps {{Leader}} and
> {{Follower}}, and throws {{JGroupsRaftException("Role [Learner] unknown.")}}
> for anything else:
> {code:java}
> switch (role) {
> case Leader: ... JGroupsRaftEventType.LEADER
> case Follower: ... JGroupsRaftEventType.FOLLOWER
> default:
> throw new JGroupsRaftException("Role [" + role + "] unknown.");
> }
> {code}
> jgroups-raft 1.1.x (Camel uses 1.1.4.Final) has a third role,
> {{org.jgroups.protocols.raft.Role.Learner}}. {{Learner extends Follower}}: it
> replicates the log but cannot vote or become leader. {{RAFT._removeServer()}}
> moves a node that is removed from the members straight from {{Leader}} to
> {{Learner}}, without passing through {{Follower}}.
> RAFT catches the exception thrown by the listener, so nothing crashes, but
> the consumer route gets no event when its node steps down from leader. A
> route that starts work on {{LEADER}} and stops it on {{FOLLOWER}} keeps
> acting as leader after the node was removed.
> {{JGroupsRaftEventType}} has no {{LEARNER}} value either.
> h3. Proposal
> * Add {{JGroupsRaftEventType.LEARNER}} and send it for {{Role.Learner}} (or,
> if a new event type is not wanted, send {{FOLLOWER}} for it, since a learner
> is a non-voting follower).
> * Do not throw for an unknown role; log it at WARN so a future role does not
> silently drop events.
> * Document the new event type in the component docs, and add a unit test that
> calls {{roleChanged(Role.Learner)}}.
> h3. Context
> Found while reviewing https://github.com/apache/camel/pull/27613 (CAMEL-25488
> / CAMEL-24598), which fixes the same gap in {{JGroupsRaftClusterView}} (the
> cluster service / master component side) but not in the consumer's
> {{CamelRoleChangeListener}}.
> _Created by Claude Code on behalf of Claus Ibsen._
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