mcvsubbu commented on a change in pull request #4323: [Controller Separation] Add logic for lead controller resource URL: https://github.com/apache/incubator-pinot/pull/4323#discussion_r306449502
########## File path: pinot-controller/src/main/java/org/apache/pinot/controller/LeadControllerManager.java ########## @@ -0,0 +1,138 @@ +/** + * 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.pinot.controller; + +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import org.apache.pinot.common.config.TableNameBuilder; +import org.apache.pinot.common.utils.helix.LeadControllerUtils; +import org.apache.pinot.controller.helix.core.PinotHelixResourceManager; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import static org.apache.pinot.common.utils.CommonConstants.Helix.NUMBER_OF_PARTITIONS_IN_LEAD_CONTROLLER_RESOURCE; + + +public class LeadControllerManager { + private static final Logger LOGGER = LoggerFactory.getLogger(LeadControllerManager.class); + + private Set<Integer> _partitionIndexCache; + private PinotHelixResourceManager _pinotHelixResourceManager; + private volatile boolean _isLeadControllerResourceEnabled = false; + private volatile boolean _amIHelixLeader = false; + + public LeadControllerManager() { + _partitionIndexCache = ConcurrentHashMap.newKeySet(); + } + + /** + * Registers {@link PinotHelixResourceManager} in LeadControllerManager, which is needed to get the external view of lead controller resource. + */ + public void registerResourceManager(PinotHelixResourceManager pinotHelixResourceManager) { + _pinotHelixResourceManager = pinotHelixResourceManager; + } + + /** + * Marks the cached indices invalid and unregisters {@link PinotHelixResourceManager}. + */ + public void stop() { + _partitionIndexCache.clear(); + _pinotHelixResourceManager = null; + } + + /** + * Checks whether the current controller is the leader for the given table. Return true if current controller is the leader for this table. + * Otherwise check whether the current controller is helix leader if the resource is disabled. + * @param tableName table name with/without table type. + */ + public boolean isLeaderForTable(String tableName) { + if (isLeadControllerResourceEnabled()) { + String rawTableName = TableNameBuilder.extractRawTableName(tableName); + int partitionIndex = LeadControllerUtils.getPartitionIdForTable(rawTableName, NUMBER_OF_PARTITIONS_IN_LEAD_CONTROLLER_RESOURCE); + return _partitionIndexCache.contains(partitionIndex); + } else { + // Checks if it's Helix leader if lead controller resource is disabled. + return isHelixLeader(); + } + } + + /** + * Given a partition name, marks current controller as lead controller for this partition by caching the partition index to current controller. + * @param partitionName partition name in lead controller resource, e.g. leadControllerResource_0. + */ + public synchronized void addPartitionLeader(String partitionName) { + LOGGER.info("Add Partition: {} to LeadControllerManager", partitionName); + int partitionIndex = LeadControllerUtils.extractPartitionIndex(partitionName); + _partitionIndexCache.add(partitionIndex); + } + + /** + * Given a partition name, removes current controller as lead controller for this partition by removing the partition index from current controller. + * @param partitionName partition name in lead controller resource, e.g. leadControllerResource_0. + */ + public synchronized void removePartitionLeader(String partitionName) { + LOGGER.info("Remove Partition: {} from LeadControllerManager", partitionName); + int partitionIndex = LeadControllerUtils.extractPartitionIndex(partitionName); + _partitionIndexCache.remove(partitionIndex); + } + + /** + * Checks if the current controller host is Helix cluster leader. + */ + private boolean isHelixLeader() { + return _amIHelixLeader; + } + + public boolean isLeadControllerResourceEnabled() { + return _isLeadControllerResourceEnabled; + } + + /** + * Callback on changes in the controller. Should be registered to the controller callback. This callback is not needed when the resource is enabled. + * However, the resource can be disabled sometime while the cluster is in operation, so we keep it here. Plus, it does not add much overhead. + * At some point in future when we stop supporting the disabled resource, we will remove this line altogether and the logic that goes with it. + */ + void onHelixControllerChange() { + if (_pinotHelixResourceManager.isHelixLeader()) { Review comment: We don't unregister from helix during shutdown, right? So, we could get this call during shutdown of the controller, and we will throw an NPE because _pinotHelixResourceManager is null. I would prefer a volatile boolean _isShuttingDown. We should stop paying attention to state changes (either for leader controller resource or controller leadership change) if we are shutting down. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
