ableegoldman commented on code in PR #16052: URL: https://github.com/apache/kafka/pull/16052#discussion_r1613071356
########## streams/src/main/java/org/apache/kafka/streams/processor/assignment/assignors/StickyTaskAssignor.java: ########## @@ -0,0 +1,478 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * 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 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.kafka.streams.processor.assignment.assignors; + +import static java.util.Collections.unmodifiableMap; + +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Set; +import java.util.TreeSet; +import java.util.stream.Collectors; +import org.apache.kafka.streams.processor.TaskId; +import org.apache.kafka.streams.processor.assignment.ApplicationState; +import org.apache.kafka.streams.processor.assignment.KafkaStreamsAssignment; +import org.apache.kafka.streams.processor.assignment.KafkaStreamsAssignment.AssignedTask; +import org.apache.kafka.streams.processor.assignment.KafkaStreamsState; +import org.apache.kafka.streams.processor.assignment.ProcessId; +import org.apache.kafka.streams.processor.assignment.TaskAssignmentUtils; +import org.apache.kafka.streams.processor.assignment.TaskAssignor; +import org.apache.kafka.streams.processor.assignment.TaskInfo; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +public class StickyTaskAssignor implements TaskAssignor { + private static final Logger LOG = LoggerFactory.getLogger(StickyTaskAssignor.class); + + private Map<String, ?> configs = new HashMap<>(); + private final boolean mustPreserveActiveTaskAssignment; + + public StickyTaskAssignor() { + this(false); + } + + public StickyTaskAssignor(final boolean mustPreserveActiveTaskAssignment) { + this.mustPreserveActiveTaskAssignment = mustPreserveActiveTaskAssignment; + } + + @Override + public void configure(final Map<String, ?> configs) { + // TODO: The application state already has the assignment configs object, why should this + // assignor be configurable? + this.configs = configs; + } + + @Override + public TaskAssignment assign(final ApplicationState applicationState) { + final int taskCount = applicationState.allTasks().size(); + if (taskCount == 0) { + return new TaskAssignment(new ArrayList<>()); + } + + final Map<ProcessId, KafkaStreamsState> clients = applicationState.kafkaStreamsStates(false); + final Map<TaskId, ProcessId> previousActiveAssignment = mapPreviousActiveTasks(clients); + final Map<TaskId, Set<ProcessId>> previousStandbyAssignment = mapPreviousStandbyTasks(clients); + final AssignmentState assignmentState = new AssignmentState(applicationState, clients, + previousActiveAssignment, previousStandbyAssignment); + + assignActive(applicationState, clients.values(), assignmentState, this.mustPreserveActiveTaskAssignment); + optimizeActive(applicationState, assignmentState); + assignStandby(applicationState, assignmentState); + optimizeStandby(applicationState, assignmentState); + return null; + } + + private void optimizeActive(final ApplicationState applicationState, + final AssignmentState assignmentState) { + if (!TaskAssignmentUtils.hasValidRackInformation(applicationState)) { Review Comment: I see, the `hasValidRackInformation` API is from PR #9. I guess it depends which one gets merged first, but maybe we should aim for this one in which case you'll need to put in a stub implementation for the build to compile However...we can't add public methods to TaskAssignmentUtils that aren't in the KIP/supposed to be part of the public API. You can add an internal assignment utils class and put things in there, it just has to be separate from the TaskAssignmentUtils and under `internals`. There might already be a class for assignment related utilities, but feel free to create one if not -- 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
