Github user joshelser commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/236#discussion_r123116460
--- Diff:
phoenix-load-balancer/src/main/java/org/apache/phoenix/loadbalancer/service/LoadBalancer.java
---
@@ -0,0 +1,170 @@
+/**
+ *
+ * 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.phoenix.loadbalancer.service;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
+import com.google.common.net.HostAndPort;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.CuratorFrameworkFactory;
+import org.apache.curator.framework.api.UnhandledErrorListener;
+import org.apache.curator.framework.recipes.cache.PathChildrenCache;
+import org.apache.curator.framework.state.ConnectionState;
+import org.apache.curator.framework.state.ConnectionStateListener;
+import org.apache.curator.retry.ExponentialBackoffRetry;
+import org.apache.curator.utils.CloseableUtils;
+import org.apache.hadoop.hbase.HBaseConfiguration;
+
+import java.net.ConnectException;
+import java.util.ArrayList;
+import java.util.concurrent.ThreadLocalRandom;
+import java.io.Closeable;
+import java.util.List;
+
+
+public class LoadBalancer {
+
+ private static final LoadBalanceZookeeperConf CONFIG = new
LoadBalanceZookeeperConfImpl(HBaseConfiguration.create());
+ private static CuratorFramework curaFramework = null;
+ protected static final Log LOG = LogFactory.getLog(LoadBalancer.class);
+ private static PathChildrenCache cache = null;
+ private static final LoadBalancer loadBalancer = new LoadBalancer();
+ private ConnectionStateListener connectionStateListener = null;
+ private UnhandledErrorListener unhandledErrorListener = null;
+ private List<Closeable> closeAbles = Lists.newArrayList();
+
+ private LoadBalancer() {
+ try {
+ start();
+ }catch(Exception ex){
+ LOG.error("Exception while creating a zookeeper clients and
cache",ex);
+ if ((curaFramework != null) && (connectionStateListener !=
null)){
+ curaFramework.getConnectionStateListenable()
+ .removeListener(connectionStateListener);
+ }
+ if ((curaFramework != null) && (unhandledErrorListener !=
null)){
+ curaFramework.getUnhandledErrorListenable()
+ .removeListener(unhandledErrorListener);
+ }
+ for (Closeable closeable : closeAbles) {
+ CloseableUtils.closeQuietly(closeable);
+ }
+ }
+ }
+
+
+
+ /**
+ * Return Singleton Load Balancer every single time.
+ * @return LoadBalancer
+ */
+ public static LoadBalancer getLoadBalancer() {
+ return loadBalancer;
+ }
+
+ /**
+ * return the location of Phoenix Query Server
--- End diff --
Javadoc could use some updating to reflect the use of HostAndPort and alert
users that they will see an exception if there are no registered PQS instances.
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