cmccabe commented on a change in pull request #10564:
URL: https://github.com/apache/kafka/pull/10564#discussion_r621639045
##########
File path:
metadata/src/main/java/org/apache/kafka/controller/ReplicationControlManager.java
##########
@@ -1119,6 +1057,83 @@ void validateManualPartitionAssignment(List<Integer>
assignment,
}
}
+ /**
+ * Iterate over a sequence of partitions and generate ISR changes and/or
leader
+ * changes if necessary.
+ *
+ * @param context A human-readable context string used in log4j
logging.
+ * @param brokerToRemove NO_LEADER if no broker is being removed; the
ID of the
Review comment:
I think it's easier to use NO_LEADER since then I don't have to
special-case the comparisons (I can just compare with NO_LEADER and it will
fail when examining ISR members, for example).
##########
File path:
metadata/src/main/java/org/apache/kafka/controller/ReplicationControlManager.java
##########
@@ -1119,6 +1057,83 @@ void validateManualPartitionAssignment(List<Integer>
assignment,
}
}
+ /**
+ * Iterate over a sequence of partitions and generate ISR changes and/or
leader
+ * changes if necessary.
+ *
+ * @param context A human-readable context string used in log4j
logging.
+ * @param brokerToRemove NO_LEADER if no broker is being removed; the
ID of the
+ * broker to remove from the ISR and leadership,
otherwise.
+ * @param brokerToAdd NO_LEADER if no broker is being added; the ID
of the
+ * broker which is now eligible to be a leader,
otherwise.
+ * @param records A list of records which we will append to.
+ * @param iterator The iterator containing the partitions to
examine.
+ */
+ void generateLeaderAndIsrUpdates(String context,
+ int brokerToRemove,
+ int brokerToAdd,
+ List<ApiMessageAndVersion> records,
+ Iterator<TopicIdPartition> iterator) {
+ int oldSize = records.size();
+ Function<Integer, Boolean> isAcceptableLeader =
+ r -> r == brokerToAdd || clusterControl.unfenced(r);
+ while (iterator.hasNext()) {
+ TopicIdPartition topicIdPart = iterator.next();
+ TopicControlInfo topic = topics.get(topicIdPart.topicId());
+ if (topic == null) {
+ throw new RuntimeException("Topic ID " + topicIdPart.topicId()
+
+ " existed in isrMembers, but not in the topics map.");
+ }
+ PartitionControlInfo partition =
topic.parts.get(topicIdPart.partitionId());
+ if (partition == null) {
+ throw new RuntimeException("Partition " + topicIdPart +
+ " existed in isrMembers, but not in the partitions map.");
+ }
+ int[] newIsr = Replicas.copyWithout(partition.isr, brokerToRemove);
+ int newLeader;
+ if (isGoodLeader(newIsr, partition.leader)) {
+ // If the current leader is good, don't change.
+ newLeader = partition.leader;
+ } else {
+ // Choose a new leader.
+ boolean uncleanOk =
configurationControl.uncleanLeaderElectionEnabledForTopic(topic.name);
+ newLeader = bestLeader(partition.replicas, newIsr, uncleanOk,
isAcceptableLeader);
Review comment:
One thing I've been considering for controlled shutdown is that perhaps
we could just keep the shutting down replicas in the ISR but move the leaders.
I think that would be a bit more graceful than what we have now, but we'd have
to do some extra work to get there.
Anyway, let's consider this later, as you suggested...
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