Bug 7391: Fix out-of-order LeaderStateChange events 01/49701/3
authorTom Pantelis <tpanteli@brocade.com>
Wed, 21 Dec 2016 14:20:36 +0000 (09:20 -0500)
committerTom Pantelis <tpanteli@brocade.com>
Thu, 22 Dec 2016 13:28:47 +0000 (13:28 +0000)
commit000960f6451af770f5463e41e1fb6defb6f3ab27
treee8d1fa2537183d19b22d5f5c8ed14f4c49887a99
parent457556047a855fdcf5fcc0570bc94b2d322997c2
Bug 7391: Fix out-of-order LeaderStateChange events

On leader transition, the current leader first sends out
LeaderTransitioning events to each follower to tell them the
current leader is being deposed. The followers send out a
LeaderStateChange event with a null leaderId which is picked
up by the ShardManager to delay subsequent transactions activity
to the shard until a new leader is elected. However it's possible
the LeaderStateChange message does not reach a follower until after
the leader transition occurs (eg due to dispatching delay in the
caller or the network). This results in a LeaderStateChange event
with a null leaderId being delivered after the LeaderStateChange
with the new leaderId. I wrote a unit test that reproduces it.

We need to handle LeaderTransitioning events in a CAS-like manner,
ie include the leaderId with the LeaderTransitioning message and
only issue the LeaderStateChange event with a null leaderId if the
current leaderId matches the leaderId in the LeaderTransitioning
message.

Change-Id: I24e8bbf7707858ac4ed62f3a979cc0403daff8ac
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>
opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActor.java
opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActorLeadershipTransferCohort.java
opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/base/messages/LeaderTransitioning.java
opendaylight/md-sal/sal-akka-raft/src/test/java/org/opendaylight/controller/cluster/raft/LeadershipTransferIntegrationTest.java
opendaylight/md-sal/sal-akka-raft/src/test/java/org/opendaylight/controller/cluster/raft/RaftActorTest.java

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