| /* |
| * 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.hadoop.hbase.master; |
| |
| import java.io.IOException; |
| import java.io.InterruptedIOException; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.hbase.Server; |
| import org.apache.hadoop.hbase.ServerName; |
| import org.apache.hadoop.hbase.monitoring.MonitoredTask; |
| import org.apache.hadoop.hbase.util.Threads; |
| import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker; |
| import org.apache.hadoop.hbase.zookeeper.ZKWatcher; |
| import org.apache.zookeeper.KeeperException; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * An implementation of HMaster that always runs as a stand by and never transitions to active. |
| */ |
| public class AlwaysStandByHMaster extends HMaster { |
| /** |
| * An implementation of ActiveMasterManager that never transitions it's master to active state. It |
| * always remains as a stand by master. With the master registry implementation (HBASE-18095) it |
| * is expected to have at least one active / standby master always running at any point in time |
| * since they serve as the gateway for client connections. |
| * |
| * With this implementation, tests can simulate the scenario of not having an active master yet |
| * the client connections to the cluster succeed. |
| */ |
| private static class AlwaysStandByMasterManager extends ActiveMasterManager { |
| private static final Logger LOG = |
| LoggerFactory.getLogger(AlwaysStandByMasterManager.class); |
| |
| AlwaysStandByMasterManager(ZKWatcher watcher, ServerName sn, Server master) |
| throws InterruptedIOException { |
| super(watcher, sn, master); |
| } |
| |
| /** |
| * An implementation that never transitions to an active master. |
| */ |
| boolean blockUntilBecomingActiveMaster(int checkInterval, MonitoredTask startupStatus) { |
| while (!(master.isAborted() || master.isStopped())) { |
| startupStatus.setStatus("Forever looping to stay as a standby master."); |
| try { |
| activeMasterServerName = null; |
| try { |
| if (MasterAddressTracker.getMasterAddress(watcher) != null) { |
| clusterHasActiveMaster.set(true); |
| } |
| } catch (IOException e) { |
| // pass, we will get notified when some other active master creates the znode. |
| } |
| Threads.sleepWithoutInterrupt(1000); |
| } catch (KeeperException e) { |
| master.abort("Received an unexpected KeeperException, aborting", e); |
| return false; |
| } |
| synchronized (this.clusterHasActiveMaster) { |
| while (clusterHasActiveMaster.get() && !master.isStopped()) { |
| try { |
| clusterHasActiveMaster.wait(checkInterval); |
| } catch (InterruptedException e) { |
| // We expect to be interrupted when a master dies, |
| // will fall out if so |
| LOG.debug("Interrupted waiting for master to die", e); |
| } |
| } |
| if (clusterShutDown.get()) { |
| this.master.stop( |
| "Cluster went down before this master became active"); |
| } |
| } |
| } |
| return false; |
| } |
| } |
| |
| public AlwaysStandByHMaster(Configuration conf) throws IOException { |
| super(conf); |
| } |
| |
| protected ActiveMasterManager createActiveMasterManager(ZKWatcher zk, ServerName sn, |
| org.apache.hadoop.hbase.Server server) throws InterruptedIOException { |
| return new AlwaysStandByMasterManager(zk, sn, server); |
| } |
| } |