cmccabe commented on code in PR #12513: URL: https://github.com/apache/kafka/pull/12513#discussion_r949680410
########## metadata/src/main/java/org/apache/kafka/controller/QuorumController.java: ########## @@ -1118,6 +1059,65 @@ private void updateWriteOffset(long offset) { } } + private void claim(int epoch) { + try { + if (curClaimEpoch != -1) { + throw new RuntimeException("Cannot claim leadership because we are already the " + + "active controller."); + } + curClaimEpoch = epoch; + controllerMetrics.setActive(true); + updateWriteOffset(lastCommittedOffset); + clusterControl.activate(); + + // Before switching to active, create an in-memory snapshot at the last committed + // offset. This is required because the active controller assumes that there is always + // an in-memory snapshot at the last committed offset. + snapshotRegistry.getOrCreateSnapshot(lastCommittedOffset); + + // Prepend the activate event. It is important that this event go at the beginning + // of the queue rather than the end (hence prepend rather than append). It's also + // important not to use prepend for anything else, to preserve the ordering here. + queue.prepend(new ControllerWriteEvent<>("completeActivation[" + epoch + "]", + new CompleteActivationEvent())); + } catch (Throwable e) { + fatalFaultHandler.handleFault("exception while claiming leadership", e); + } + } + + class CompleteActivationEvent implements ControllerWriteOperation<Void> { + @Override + public ControllerResult<Void> generateRecordsAndResult() throws Exception { + List<ApiMessageAndVersion> records = new ArrayList<>(); + if (logReplayTracker.empty()) { + // If no records have been replayed, we need to write out the bootstrap records. + // This will include the new metadata.version, as well as things like SCRAM + // initialization, etc. + log.warn("The metadata log appears to be empty. Appending {} bootstrap record(s) " + Review Comment: Ehh... `warn` seems appropriate. We are upgrading your `metadata.version`, it's kind of a big deal. You will also only ever see this once -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org