XComp commented on code in PR #22380:
URL: https://github.com/apache/flink/pull/22380#discussion_r1169826770
##########
flink-runtime/src/main/java/org/apache/flink/runtime/leaderelection/DefaultLeaderElectionService.java:
##########
@@ -77,22 +100,48 @@ public
DefaultLeaderElectionService(LeaderElectionDriverFactory leaderElectionDr
this.leaderElectionDriver = null;
this.confirmedLeaderInformation = LeaderInformation.empty();
+ }
- this.running = false;
+ /**
+ * Starts the leader election process. This method has to be called before
registering a {@link
+ * LeaderContender}.
+ */
+ public void startLeaderElectionBackend() throws Exception {
+ synchronized (lock) {
+ Preconditions.checkState(
+ leaderContender == null,
+ "No LeaderContender should have been registered, yet.");
+
+ leaderElectionDriver =
+ leaderElectionDriverFactory.createLeaderElectionDriver(
+ this, new LeaderElectionFatalErrorHandler());
+
+ LOG.info("Instantiating DefaultLeaderElectionService with {}.",
leaderElectionDriver);
+ }
}
@Override
public final void start(LeaderContender contender) throws Exception {
checkNotNull(contender, "Contender must not be null.");
- Preconditions.checkState(leaderContender == null, "Contender was
already set.");
synchronized (lock) {
- running = true;
+ Preconditions.checkState(
+ leaderContender == null,
+ "Only one LeaderContender is allowed to be registered to
this service.");
+ Preconditions.checkState(
+ leaderElectionDriver != null,
+ "The DefaultLeaderElectionService should have established
a connection to the backend before it's started.");
+
leaderContender = contender;
- leaderElectionDriver =
- leaderElectionDriverFactory.createLeaderElectionDriver(
- this, new LeaderElectionFatalErrorHandler());
- LOG.info("Starting DefaultLeaderElectionService with {}.",
leaderElectionDriver);
+
+ LOG.info(
+ "LeaderContender {} has been registered for {}.",
+ contender.getDescription(),
+ leaderElectionDriver);
+
+ if (hasLeadership()) {
+ notifyLeaderContenderOfLeadership();
Review Comment:
args, that's a good catch - I haven't thought about it in that way. I was
planning to include a `singleThreadExecutor` similarly to what we have in
`DefaultMultipleComponentLeaderElectionService` but hoped that it could be done
in a separate PR. But it looks like I have to integrate that one in here as
well. :roll_eyes: I'm going to work on it.
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