junrao commented on a change in pull request #10753: URL: https://github.com/apache/kafka/pull/10753#discussion_r669208386
########## File path: metadata/src/main/java/org/apache/kafka/controller/PartitionReassignmentRevert.java ########## @@ -0,0 +1,89 @@ +/* + * 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.controller; + +import org.apache.kafka.metadata.PartitionRegistration; +import org.apache.kafka.metadata.Replicas; + +import java.util.ArrayList; +import java.util.Set; +import java.util.List; +import java.util.Objects; + + +class PartitionReassignmentRevert { + private final List<Integer> replicas; + private final List<Integer> isr; + + PartitionReassignmentRevert(PartitionRegistration registration) { + // Figure out the replica list and ISR that we will have after reverting the + // reassignment. In general, we want to take out any replica that the reassignment + // was adding, but keep the ones the reassignment was removing. (But see the + // special case below.) + Set<Integer> adding = Replicas.toSet(registration.addingReplicas); + this.replicas = new ArrayList<>(registration.replicas.length); + this.isr = new ArrayList<>(registration.isr.length); + for (int i = 0; i < registration.isr.length; i++) { + int replica = registration.isr[i]; + if (!adding.contains(replica)) { + this.isr.add(replica); + } else if (i == registration.isr.length - 1 && isr.isEmpty()) { + // This is a special case where taking out all the "adding" replicas is + // not possible. The reason it is not possible is that doing so would + // create an empty ISR, which is not allowed. + // + // In this case, we leave in one of the adding replicas permanently. Review comment: One weird side effect of doing this is that it can change the replication factor for a partition to be different from the original one. -- 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
