/**
*
* 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 com.alibaba.wasp.zookeeper;
import com.alibaba.wasp.ServerName;
import com.alibaba.wasp.master.FServerManager;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.Abortable;
import org.apache.zookeeper.KeeperException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.NavigableSet;
import java.util.TreeSet;
/**
* Tracks the online fservers 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 FS node gets deleted, this automatically handles calling of
* {@link com.alibaba.wasp.master.FServerManager#expireServer(com.alibaba.wasp.ServerName)}
*/
public class FServerTracker extends ZooKeeperListener {
protected static final Log LOG = LogFactory.getLog(FServerTracker.class);
private NavigableSet<ServerName> fservers = new TreeSet<ServerName>();
private FServerManager serverManager;
private Abortable abortable;
public FServerTracker(ZooKeeperWatcher watcher, Abortable abortable,
FServerManager serverManager) {
super(watcher);
this.abortable = abortable;
this.serverManager = serverManager;
}
/**
* Starts the tracking of online FServers.
*
* <p>
* All RSs will be tracked after this method is called.
*
* @throws org.apache.zookeeper.KeeperException
* @throws java.io.IOException
*/
public void start() throws KeeperException, IOException {
watcher.registerListener(this);
List<String> servers = ZKUtil.listChildrenAndWatchThem(watcher,
watcher.fsZNode);
add(servers);
}
protected void add(final List<String> servers) throws IOException {
synchronized (this.fservers) {
this.fservers.clear();
for (String n : servers) {
ServerName sn = ServerName.parseServerName(ZKUtil.getNodeName(n));
this.fservers.add(sn);
}
}
}
protected void remove(final ServerName sn) {
synchronized (this.fservers) {
this.fservers.remove(sn);
}
}
@Override
public void nodeDeleted(String path) {
if (path.startsWith(watcher.fsZNode)) {
String serverName = ZKUtil.getNodeName(path);
LOG.info("FServer ephemeral node deleted, processing expiration ["
+ serverName + "]");
ServerName sn = ServerName.parseServerName(serverName);
if (!serverManager.isServerOnline(sn)) {
LOG.warn(serverName.toString()
+ " is not online or isn't known to the master."
+ "The latter could be caused by a DNS misconfiguration.");
return;
}
remove(sn);
this.serverManager.expireServer(sn);
}
}
@Override
public void nodeChildrenChanged(String path) {
if (path.equals(watcher.fsZNode)) {
try {
List<String> servers = ZKUtil.listChildrenAndWatchThem(watcher,
watcher.fsZNode);
add(servers);
} catch (IOException e) {
abortable.abort("Unexpected zk exception getting RS nodes", e);
} catch (KeeperException e) {
abortable.abort("Unexpected zk exception getting RS nodes", e);
}
}
}
/**
* Gets the online servers.
*
* @return list of online servers
*/
public List<ServerName> getOnlineServers() {
synchronized (this.fservers) {
return new ArrayList<ServerName>(this.fservers);
}
}
}