mgao0 commented on a change in pull request #727: Add MetadataStoreRoutingDataWriter with DistributedLeaderElection URL: https://github.com/apache/helix/pull/727#discussion_r376660661
########## File path: helix-rest/src/main/java/org/apache/helix/rest/metadatastore/accessor/ZkRoutingDataWriter.java ########## @@ -0,0 +1,256 @@ +package org.apache.helix.rest.metadatastore.accessor; + +/* + * 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.Collections; +import java.util.List; +import java.util.Map; + +import org.I0Itec.zkclient.exception.ZkNodeExistsException; +import org.apache.helix.ZNRecord; +import org.apache.helix.manager.zk.ZNRecordSerializer; +import org.apache.helix.manager.zk.ZkBaseDataAccessor; +import org.apache.helix.manager.zk.client.DedicatedZkClientFactory; +import org.apache.helix.manager.zk.client.HelixZkClient; +import org.apache.helix.rest.metadatastore.concurrency.ZkDistributedLeaderElection; +import org.apache.helix.rest.metadatastore.constant.MetadataStoreRoutingConstants; +import org.apache.helix.rest.metadatastore.exceptions.ZkLockException; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +public class ZkRoutingDataWriter implements MetadataStoreRoutingDataWriter { + private static final Logger LOG = LoggerFactory.getLogger(ZkBaseDataAccessor.class); + + private final String _namespace; + private final String _zkAddress; + private final HelixZkClient _zkClient; + private final ZkDistributedLeaderElection _leaderElection; + + public ZkRoutingDataWriter(String namespace, String zkAddress) { + if (namespace == null || namespace.isEmpty()) { + throw new IllegalArgumentException("namespace cannot be null or empty!"); + } + _namespace = namespace; + if (zkAddress == null || zkAddress.isEmpty()) { + throw new IllegalArgumentException("Zk address cannot be null or empty!"); + } + _zkAddress = zkAddress; + _zkClient = DedicatedZkClientFactory.getInstance() + .buildZkClient(new HelixZkClient.ZkConnectionConfig(zkAddress), + new HelixZkClient.ZkClientConfig().setZkSerializer(new ZNRecordSerializer())); + + // Ensure that ROUTING_DATA_PATH exists in ZK. If not, create + // create() semantic will fail if it already exists + try { + _zkClient.createPersistent(MetadataStoreRoutingConstants.ROUTING_DATA_PATH); + } catch (ZkNodeExistsException e) { + // This is okay + } + + // Get the hostname (REST endpoint) from System property + ZNRecord myServerInfo = new ZNRecord("dummy hostname"); + _leaderElection = new ZkDistributedLeaderElection(_zkClient, + MetadataStoreRoutingConstants.LEADER_ELECTION_ZNODE, myServerInfo); + } + + @Override + public synchronized boolean addMetadataStoreRealm(String realm) { + if (_leaderElection.isLeader()) { + if (_zkClient.isClosed()) { + throw new IllegalStateException("ZkClient is closed!"); + } + return createZkRealm(realm); + } + + // TODO: Forward the request to leader + return true; + } + + @Override + public synchronized boolean deleteMetadataStoreRealm(String realm) { + if (_leaderElection.isLeader()) { + if (_zkClient.isClosed()) { + throw new IllegalStateException("ZkClient is closed!"); + } + return _zkClient.delete(MetadataStoreRoutingConstants.ROUTING_DATA_PATH + "/" + realm); + } + + // TODO: Forward the request to leader + return true; + } + + @Override + public synchronized boolean addShardingKey(String realm, String shardingKey) { + if (_leaderElection.isLeader()) { + if (_zkClient.isClosed()) { + throw new IllegalStateException("ZkClient is closed!"); + } + // If the realm does not exist already, then create the realm + if (!_zkClient.exists(MetadataStoreRoutingConstants.ROUTING_DATA_PATH + "/" + realm)) { Review comment: Can you create a variable for the path so you don't need to repeatedly type it out? ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
