| package org.apache.helix.controller.rebalancer.waged; |
| |
| /* |
| * 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. |
| */ |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Optional; |
| |
| import org.apache.helix.HelixRebalanceException; |
| import org.apache.helix.controller.dataproviders.ResourceControllerDataProvider; |
| import org.apache.helix.controller.rebalancer.waged.constraints.ConstraintBasedAlgorithmFactory; |
| import org.apache.helix.manager.zk.ZkBucketDataAccessor; |
| import org.apache.helix.model.ClusterConfig; |
| import org.apache.helix.model.ResourceAssignment; |
| |
| |
| /** |
| * This rebalancer is a version of WagedRebalancer that only reads the existing assignment metadata |
| * to compute the best possible assignment but never writes back the resulting assignment metadata |
| * from global or partial rebalance. It does so by using a modified version of |
| * AssignmentMetadataStore, ReadOnlyAssignmentMetadataStore. |
| * |
| * This class is to be used in the cluster verifiers, tests, or util methods. |
| */ |
| public class ReadOnlyWagedRebalancer extends WagedRebalancer { |
| public ReadOnlyWagedRebalancer(ZkBucketDataAccessor zkBucketDataAccessor, String clusterName, |
| Map<ClusterConfig.GlobalRebalancePreferenceKey, Integer> preferences) { |
| super(new ReadOnlyAssignmentMetadataStore(zkBucketDataAccessor, clusterName), |
| ConstraintBasedAlgorithmFactory.getInstance(preferences), Optional.empty()); |
| } |
| |
| @Override |
| protected List<HelixRebalanceException.Type> failureTypesToPropagate() { |
| // Also propagate FAILED_TO_CALCULATE for ReadOnlyWagedRebalancer |
| List<HelixRebalanceException.Type> failureTypes = |
| new ArrayList<>(super.failureTypesToPropagate()); |
| failureTypes.add(HelixRebalanceException.Type.FAILED_TO_CALCULATE); |
| return failureTypes; |
| } |
| |
| public void updateChangeDetectorSnapshots(ResourceControllerDataProvider dataProvider) { |
| getChangeDetector().updateSnapshots(dataProvider); |
| } |
| |
| private static class ReadOnlyAssignmentMetadataStore extends AssignmentMetadataStore { |
| |
| ReadOnlyAssignmentMetadataStore(ZkBucketDataAccessor zkBucketDataAccessor, String clusterName) { |
| super(zkBucketDataAccessor, clusterName); |
| } |
| |
| @Override |
| public boolean persistBaseline(Map<String, ResourceAssignment> globalBaseline) { |
| // If baseline hasn't changed, skip updating the metadata store |
| if (compareAssignments(_globalBaseline, globalBaseline)) { |
| return false; |
| } |
| // Update the in-memory reference only |
| _globalBaseline = globalBaseline; |
| return true; |
| } |
| |
| @Override |
| public boolean persistBestPossibleAssignment( |
| Map<String, ResourceAssignment> bestPossibleAssignment) { |
| // If bestPossibleAssignment hasn't changed, skip updating the metadata store |
| if (compareAssignments(_bestPossibleAssignment, bestPossibleAssignment)) { |
| return false; |
| } |
| // Update the in-memory reference only |
| _bestPossibleAssignment = bestPossibleAssignment; |
| return true; |
| } |
| |
| @Override |
| // BucketDataAccessor will be reused, won't be closed here. |
| public void close() { |
| } |
| } |
| } |