org.apache.accumulo.server.master.TabletServerLoggers.java Source code

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Here is the source code for org.apache.accumulo.server.master.TabletServerLoggers.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 org.apache.accumulo.server.master;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.accumulo.core.Constants;
import org.apache.accumulo.core.conf.AccumuloConfiguration;
import org.apache.accumulo.core.zookeeper.ZooUtil;
import org.apache.accumulo.server.client.HdfsZooInstance;
import org.apache.accumulo.server.zookeeper.ZooCache;
import org.apache.log4j.Logger;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;

public class TabletServerLoggers implements Watcher {

    private static final Logger log = Logger.getLogger(TabletServerLoggers.class);

    // Map from zookeeper path to address
    private Map<String, String> names = new HashMap<String, String>();

    private ZooCache cache;
    private LoggerWatcher watcher;

    interface LoggerWatcher {
        void newLogger(String address);

        void deadLogger(String address);
    }

    public TabletServerLoggers(LoggerWatcher watcher, AccumuloConfiguration conf) {
        cache = new ZooCache(conf, this);
        this.watcher = watcher;
    }

    private String loggerPath() {
        return ZooUtil.getRoot(HdfsZooInstance.getInstance()) + Constants.ZLOGGERS;
    }

    synchronized public Map<String, String> getLoggersFromZooKeeper() {
        String path = loggerPath();
        Map<String, String> current = new HashMap<String, String>();
        for (String child : cache.getChildren(path)) {
            byte[] value = cache.get(path + "/" + child);
            if (value != null)
                current.put(child, new String(value));
        }
        return current;
    }

    synchronized public void scanZooKeeperForUpdates() {
        Map<String, String> current = getLoggersFromZooKeeper();
        if (log.isDebugEnabled()) {
            if (current.entrySet().size() < 100) {
                for (Entry<String, String> entry : current.entrySet())
                    log.debug("looking at logger " + entry.getKey() + " -> " + entry.getValue());
            } else {
                log.debug("looking at " + current.entrySet().size() + " loggers");
            }
        }
        Set<String> currentAddresses = new HashSet<String>(current.values());
        Set<String> deleted = new HashSet<String>(names.keySet());
        deleted.removeAll(current.keySet());
        Set<String> new_ = new HashSet<String>(current.keySet());
        new_.removeAll(names.keySet());
        for (String logger : deleted) {
            String address = names.get(logger);
            if (!currentAddresses.contains(address)) {
                watcher.deadLogger(address);
            }
        }
        for (String logger : new_) {
            String address = current.get(logger);
            watcher.newLogger(address);
        }
        names = current;
    }

    @Override
    public void process(WatchedEvent event) {
        try {
            scanZooKeeperForUpdates();
        } catch (Exception ex) {
            log.info("Got exception scanning zookeeper", ex);
        }
    }
}