/**
* Copyright 2010 The Apache Software Foundation
*
* 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.zookeeper;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.HServerAddress;
import org.apache.hadoop.hbase.HServerInfo;
import org.apache.hadoop.hbase.master.ServerManager;
import org.apache.zookeeper.KeeperException;
/**
* Tracks the online region servers via ZK.
*
* <p>Handling of new RSs checking in is done via RPC. This class
* is only responsible for watching for expired nodes. It handles
* listening for changes in the RS node list and watching each node.
*
* <p>If an RS node gets deleted, this automatically handles calling of
* {@link ServerManager#expireServer(org.apache.hadoop.hbase.HServerInfo)}.
*/
public class RegionServerTracker extends ZooKeeperListener {
private static final Log LOG = LogFactory.getLog(RegionServerTracker.class);
private ServerManager serverManager;
private Abortable abortable;
public RegionServerTracker(ZooKeeperWatcher watcher,
Abortable abortable, ServerManager serverManager) {
super(watcher);
this.abortable = abortable;
this.serverManager = serverManager;
}
/**
* Starts the tracking of online RegionServers.
*
* <p>All RSs will be tracked after this method is called.
*
* @throws KeeperException
*/
public void start() throws KeeperException {
watcher.registerListener(this);
ZKUtil.watchAndGetNewChildren(watcher, watcher.rsZNode);
}
@Override
public void nodeDeleted(String path) {
if(path.startsWith(watcher.rsZNode)) {
String serverName = ZKUtil.getNodeName(path);
LOG.info("RegionServer ephemeral node deleted, processing expiration [" +
serverName + "]");
HServerInfo hsi = serverManager.getServerInfo(serverName);
if(hsi == null) {
LOG.info("No HServerInfo found for " + serverName);
return;
}
serverManager.expireServer(hsi);
}
}
@Override
public void nodeChildrenChanged(String path) {
if(path.equals(watcher.rsZNode)) {
try {
ZKUtil.watchAndGetNewChildren(watcher, watcher.rsZNode);
} catch (KeeperException e) {
abortable.abort("Unexpected zk exception getting RS nodes", e);
}
}
}
/**
* Gets the online servers.
* @return list of online servers from zk
* @throws KeeperException
*/
public List<HServerAddress> getOnlineServers() throws KeeperException {
return ZKUtil.listChildrenAndGetAsAddresses(watcher, watcher.rsZNode);
}
}