Examples with NO_LEADER org.apache.kafka.metadata.LeaderConstants.NO_LEADER used on opensource projects

Example 1 with NO_LEADER

use of org.apache.kafka.metadata.LeaderConstants.NO_LEADER in project kafka by apache.

the class ReplicationControlManager method generateLeaderAndIsrUpdates.

/**
 * 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();
    // If the caller passed a valid broker ID for brokerToAdd, rather than passing
    // NO_LEADER, that node will be considered an acceptable leader even if it is
    // currently fenced. This is useful when handling unfencing. The reason is that
    // while we're generating the records to handle unfencing, the ClusterControlManager
    // still shows the node as fenced.
    // 
    // Similarly, if the caller passed a valid broker ID for brokerToRemove, rather
    // than passing NO_LEADER, that node will never be considered an acceptable leader.
    // This is useful when handling a newly fenced node. We also exclude brokerToRemove
    // from the target ISR, but we need to exclude it here too, to handle the case
    // where there is an unclean leader election which chooses a leader from outside
    // the ISR.
    Function<Integer, Boolean> isAcceptableLeader = r -> (r != brokerToRemove) && (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.");
        }
        PartitionRegistration partition = topic.parts.get(topicIdPart.partitionId());
        if (partition == null) {
            throw new RuntimeException("Partition " + topicIdPart + " existed in isrMembers, but not in the partitions map.");
        }
        PartitionChangeBuilder builder = new PartitionChangeBuilder(partition, topicIdPart.topicId(), topicIdPart.partitionId(), isAcceptableLeader, () -> configurationControl.uncleanLeaderElectionEnabledForTopic(topic.name));
        // Note: if brokerToRemove was passed as NO_LEADER, this is a no-op (the new
        // target ISR will be the same as the old one).
        builder.setTargetIsr(Replicas.toList(Replicas.copyWithout(partition.isr, brokerToRemove)));
        builder.build().ifPresent(records::add);
    }
    if (records.size() != oldSize) {
        if (log.isDebugEnabled()) {
            StringBuilder bld = new StringBuilder();
            String prefix = "";
            for (ListIterator<ApiMessageAndVersion> iter = records.listIterator(oldSize); iter.hasNext(); ) {
                ApiMessageAndVersion apiMessageAndVersion = iter.next();
                PartitionChangeRecord record = (PartitionChangeRecord) apiMessageAndVersion.message();
                bld.append(prefix).append(topics.get(record.topicId()).name).append("-").append(record.partitionId());
                prefix = ", ";
            }
            log.debug("{}: changing partition(s): {}", context, bld.toString());
        } else if (log.isInfoEnabled()) {
            log.info("{}: changing {} partition(s)", context, records.size() - oldSize);
        }
    }
}