| /** |
| * 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 |
| * <p/> |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * <p/> |
| * 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.hadoop.metrics2.sink.timeline.availability; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.curator.CuratorZookeeperClient; |
| import org.apache.curator.RetryLoop; |
| import org.apache.curator.RetryPolicy; |
| import org.apache.curator.retry.BoundedExponentialBackoffRetry; |
| import org.apache.zookeeper.ZooKeeper; |
| import org.apache.zookeeper.data.Stat; |
| |
| import java.util.Collection; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| import java.util.concurrent.Callable; |
| |
| /** |
| * Find a live Collector instance from Zookeeper |
| * This class allows connect to ZK on-demand and |
| * does not add a watcher on the znode. |
| */ |
| public class MetricCollectorHAHelper { |
| private final String zookeeperConnectionURL; |
| private final int tryCount; |
| private final int sleepMsBetweenRetries; |
| |
| private static final int CONNECTION_TIMEOUT = 2000; |
| private static final int SESSION_TIMEOUT = 10000; |
| private static final String ZNODE = "/ambari-metrics-cluster"; |
| private static final String ZK_PATH = ZNODE + "/LIVEINSTANCES"; |
| private static final String INSTANCE_NAME_DELIMITER = "_"; |
| |
| |
| |
| private static final Log LOG = LogFactory.getLog(MetricCollectorHAHelper.class); |
| |
| public MetricCollectorHAHelper(String zookeeperConnectionURL, int tryCount, int sleepMsBetweenRetries) { |
| this.zookeeperConnectionURL = zookeeperConnectionURL; |
| this.tryCount = tryCount; |
| this.sleepMsBetweenRetries = sleepMsBetweenRetries; |
| } |
| |
| /** |
| * Connect to Zookeeper to find live instances of metrics collector |
| * @return {#link Collection} hostnames |
| */ |
| public Collection<String> findLiveCollectorHostsFromZNode() { |
| Set<String> collectors = new HashSet<>(); |
| |
| RetryPolicy retryPolicy = new BoundedExponentialBackoffRetry(sleepMsBetweenRetries, 10*sleepMsBetweenRetries, tryCount); |
| final CuratorZookeeperClient client = new CuratorZookeeperClient(zookeeperConnectionURL, |
| SESSION_TIMEOUT, CONNECTION_TIMEOUT, null, retryPolicy); |
| |
| List<String> liveInstances = null; |
| |
| try { |
| client.start(); |
| //Check if Znode exists |
| Stat stat = client.getZooKeeper().exists(ZNODE, false); |
| if (stat == null) { |
| LOG.info("/ambari-metrics-cluster znode does not exist. Skipping requesting live instances from zookeeper"); |
| return collectors; |
| } |
| liveInstances = RetryLoop.callWithRetry(client, new Callable<List<String>>() { |
| @Override |
| public List<String> call() throws Exception { |
| ZooKeeper zookeeper = client.getZooKeeper(); |
| return zookeeper.getChildren(ZK_PATH, false); |
| } |
| }); |
| } catch (Exception e) { |
| LOG.warn("Unable to connect to zookeeper.", e); |
| LOG.debug(e); |
| } finally { |
| try { |
| client.close(); |
| } catch (Exception e) { |
| LOG.error("Caught exception while trying to close Zk connection.",e); |
| } |
| } |
| |
| // [ambari-sid-3.c.pramod-thangali.internal_12001] |
| if (liveInstances != null && !liveInstances.isEmpty()) { |
| for (String instanceStr : liveInstances) { |
| collectors.add(instanceStr.substring(0, instanceStr.indexOf(INSTANCE_NAME_DELIMITER))); |
| } |
| } |
| |
| return collectors; |
| } |
| } |