hbase-server/src/test/java/org/apache/hadoop/hbase/master/AlwaysStandByHMaster.java

   1 /*
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.master;
  19
  20 import java.io.IOException;
  21 import java.io.InterruptedIOException;
  22 import org.apache.hadoop.conf.Configuration;
  23 import org.apache.hadoop.hbase.Server;
  24 import org.apache.hadoop.hbase.ServerName;
  25 import org.apache.hadoop.hbase.monitoring.MonitoredTask;
  26 import org.apache.hadoop.hbase.util.Threads;
  27 import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker;
  28 import org.apache.hadoop.hbase.zookeeper.ZKWatcher;
  29 import org.apache.zookeeper.KeeperException;
  30 import org.slf4j.Logger;
  31 import org.slf4j.LoggerFactory;
  32
  33 /**
  34  * An implementation of HMaster that always runs as a stand by and never transitions to active.
  35  */
  36 public class AlwaysStandByHMaster extends HMaster {
  37   /**
  38    * An implementation of ActiveMasterManager that never transitions it's master to active state. It
  39    * always remains as a stand by master. With the master registry implementation (HBASE-18095) it
  40    * is expected to have at least one active / standby master always running at any point in time
  41    * since they serve as the gateway for client connections.
  42    *
  43    * With this implementation, tests can simulate the scenario of not having an active master yet
  44    * the client connections to the cluster succeed.
  45    */
  46   private static class AlwaysStandByMasterManager extends ActiveMasterManager {
  47     private static final Logger LOG =
  48         LoggerFactory.getLogger(AlwaysStandByMasterManager.class);
  49
  50     AlwaysStandByMasterManager(ZKWatcher watcher, ServerName sn, Server master)
  51         throws InterruptedIOException {
  52       super(watcher, sn, master);
  53     }
  54
  55     /**
  56      * An implementation that never transitions to an active master.
  57      */
  58     boolean blockUntilBecomingActiveMaster(int checkInterval, MonitoredTask startupStatus) {
  59       while (!(master.isAborted() || master.isStopped())) {
  60         startupStatus.setStatus("Forever looping to stay as a standby master.");
  61         try {
  62           activeMasterServerName = null;
  63           try {
  64             if (MasterAddressTracker.getMasterAddress(watcher) != null) {
  65               clusterHasActiveMaster.set(true);
  66             }
  67           } catch (IOException e) {
  68             // pass, we will get notified when some other active master creates the znode.
  69           }
  70           Threads.sleepWithoutInterrupt(1000);
  71         } catch (KeeperException e) {
  72           master.abort("Received an unexpected KeeperException, aborting", e);
  73           return false;
  74         }
  75         synchronized (this.clusterHasActiveMaster) {
  76           while (clusterHasActiveMaster.get() && !master.isStopped()) {
  77             try {
  78               clusterHasActiveMaster.wait(checkInterval);
  79             } catch (InterruptedException e) {
  80               // We expect to be interrupted when a master dies,
  81               //  will fall out if so
  82               LOG.debug("Interrupted waiting for master to die", e);
  83             }
  84           }
  85           if (clusterShutDown.get()) {
  86             this.master.stop(
  87                 "Cluster went down before this master became active");
  88           }
  89         }
  90       }
  91       return false;
  92     }
  93   }
  94
  95   public AlwaysStandByHMaster(Configuration conf) throws IOException {
  96     super(conf);
  97   }
  98
  99   protected ActiveMasterManager createActiveMasterManager(ZKWatcher zk, ServerName sn,
 100       org.apache.hadoop.hbase.Server server) throws InterruptedIOException {
 101     return new AlwaysStandByMasterManager(zk, sn, server);
 102   }
 103 }