Github user revans2 commented on a diff in the pull request: https://github.com/apache/storm/pull/1047#discussion_r50853930 --- Diff: storm-core/src/jvm/org/apache/storm/zookeeper/LeaderElectorImp.java --- @@ -0,0 +1,135 @@ +/** + * 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.storm.zookeeper; + +import org.apache.curator.framework.CuratorFramework; +import org.apache.curator.framework.recipes.leader.LeaderLatch; +import org.apache.curator.framework.recipes.leader.LeaderLatchListener; +import org.apache.curator.framework.recipes.leader.Participant; +import org.apache.storm.nimbus.ILeaderElector; +import org.apache.storm.nimbus.NimbusInfo; +import org.apache.storm.utils.Utils; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Collection; +import java.util.List; +import java.util.Map; +import java.util.concurrent.atomic.AtomicReference; + + +public class LeaderElectorImp implements ILeaderElector { + private static Logger LOG = LoggerFactory.getLogger(LeaderElectorImp.class); + private Map conf; + private List<String> servers; + private CuratorFramework zk; + private String leaderlockPath; + private String id; + private AtomicReference<LeaderLatch> leaderLatch; + private AtomicReference<LeaderLatchListener> leaderLatchListener; + + public LeaderElectorImp(Map conf, List<String> servers, CuratorFramework zk, String leaderlockPath, String id, AtomicReference<LeaderLatch> leaderLatch, + AtomicReference<LeaderLatchListener> leaderLatchListener) { + this.conf = conf; + this.servers = servers; + this.zk = zk; + this.leaderLatch = leaderLatch; + this.id = id; + this.leaderLatch = leaderLatch; + this.leaderLatchListener = leaderLatchListener; + } + + @Override + public void prepare(Map conf) { + LOG.info("no-op for zookeeper implementation"); + } + + @Override + public void addToLeaderLockQueue() { + // if this latch is already closed, we need to create new instance. + try { + if (LeaderLatch.State.CLOSED.equals(leaderLatch.get().getState())) { + leaderLatch.set(new LeaderLatch(zk, leaderlockPath)); + leaderLatchListener.set(Zookeeper.leaderLatchListenerImpl(conf, zk, leaderLatch.get())); + } + // Only if the latch is not already started we invoke start + if (LeaderLatch.State.LATENT.equals(leaderLatch.get().getState())) { + leaderLatch.get().addListener(leaderLatchListener.get()); + leaderLatch.get().start(); + LOG.info("Queued up for leader lock."); + } else { + LOG.info("Node already in queue for leader lock."); + } + } catch (Exception e) { + LOG.warn("failed to add LeaderLatchListener", e); + } + + } + + @Override + // Only started latches can be closed. + public void removeFromLeaderLockQueue() { + if (LeaderLatch.State.STARTED.equals(leaderLatch.get().getState())) { + try { + leaderLatch.get().close(); + LOG.info("Removed from leader lock queue."); + } catch (IOException e) { + LOG.warn("failed to close leaderLatch!!"); + } --- End diff -- Here too, lets not eat the exception. At least wrap it and rethrow it, but preferably update the Interface to allow us to throw it as is.
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