com.alibaba.wasp.zookeeper.FServerTracker.java Source code

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Here is the source code for com.alibaba.wasp.zookeeper.FServerTracker.java

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/**
 *
 * 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);
        }
    }
}