org.apache.kafka.streams.processor.internals.assignment.DefaultStandbyTaskAssignor Maven / Gradle / Ivy
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* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.kafka.streams.processor.internals.assignment;
import org.apache.kafka.streams.processor.TaskId;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Map;
import java.util.Set;
import java.util.UUID;
import static org.apache.kafka.streams.processor.internals.assignment.StandbyTaskAssignmentUtils.computeTasksToRemainingStandbys;
import static org.apache.kafka.streams.processor.internals.assignment.StandbyTaskAssignmentUtils.createLeastLoadedPrioritySetConstrainedByAssignedTask;
import static org.apache.kafka.streams.processor.internals.assignment.StandbyTaskAssignmentUtils.pollClientAndMaybeAssignAndUpdateRemainingStandbyTasks;
/**
* Default standby task assignor that distributes standby tasks to the least loaded clients.
*
* @see ClientTagAwareStandbyTaskAssignor
*/
class DefaultStandbyTaskAssignor implements StandbyTaskAssignor {
private static final Logger log = LoggerFactory.getLogger(DefaultStandbyTaskAssignor.class);
@Override
public boolean assign(final Map clients,
final Set allTaskIds,
final Set statefulTaskIds,
final AssignorConfiguration.AssignmentConfigs configs) {
final int numStandbyReplicas = configs.numStandbyReplicas;
final Map tasksToRemainingStandbys = computeTasksToRemainingStandbys(numStandbyReplicas,
statefulTaskIds);
final ConstrainedPrioritySet standbyTaskClientsByTaskLoad = createLeastLoadedPrioritySetConstrainedByAssignedTask(clients);
standbyTaskClientsByTaskLoad.offerAll(clients.keySet());
for (final TaskId task : statefulTaskIds) {
pollClientAndMaybeAssignAndUpdateRemainingStandbyTasks(numStandbyReplicas,
clients,
tasksToRemainingStandbys,
standbyTaskClientsByTaskLoad,
task,
log);
}
// returning false, because standby task assignment will never require a follow-up probing rebalance.
return false;
}
}