org.apache.hama.bsp.sync.ZKSyncBSPMasterClient.java Source code

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Here is the source code for org.apache.hama.bsp.sync.ZKSyncBSPMasterClient.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.hama.bsp.sync;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hama.Constants;
import org.apache.hama.HamaConfiguration;
import org.apache.hama.zookeeper.QuorumPeer;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

/**
 * Zookeeper sunchronization client that is used by BSPMaster to maintain global
 * state of cluster.
 */
public class ZKSyncBSPMasterClient extends ZKSyncClient implements MasterSyncClient {

    private ZooKeeper zk = null;
    private String bspRoot = null;

    Log LOG = LogFactory.getLog(ZKSyncBSPMasterClient.class);

    @Override
    public void init(HamaConfiguration conf) {
        try {
            zk = new ZooKeeper(QuorumPeer.getZKQuorumServersString(conf),
                    conf.getInt(Constants.ZOOKEEPER_SESSION_TIMEOUT, 1200000), this);
        } catch (IOException e) {
            LOG.error("Exception during reinitialization!", e);
        }

        bspRoot = conf.get(Constants.ZOOKEEPER_ROOT, Constants.DEFAULT_ZOOKEEPER_ROOT);
        LOG.info("Initialized ZK " + (null == zk));
        Stat s = null;
        if (zk != null) {
            initialize(zk, bspRoot);
            try {
                s = zk.exists(bspRoot, false);
            } catch (Exception e) {
                LOG.error(s, e);
            }

            if (s == null) {
                try {
                    zk.create(bspRoot, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
                } catch (KeeperException e) {
                    LOG.error(e);
                } catch (InterruptedException e) {
                    LOG.error(e);
                }
            } else {
                this.clearZKNodes();
            }
        }

    }

    private void createJobRoot(String string) {
        writeNode(string, null, true, null);
    }

    @Override
    public void clear() {
        clearZKNodes();
    }

    @Override
    public void registerJob(String string) {
        // TODO: delete job root if key is present.
        createJobRoot(bspRoot + "/" + string);
    }

    @Override
    public void deregisterJob(String string) {
        try {
            clearZKNodes(bspRoot + "/" + string);
            this.zk.delete(bspRoot + "/" + string, -1);
        } catch (KeeperException e) {
            LOG.error("Error deleting job " + string);
        } catch (InterruptedException e) {
            LOG.error("Error deleting job " + string);
        }

    }

    @Override
    public void close() {
        try {
            this.zk.close();
        } catch (InterruptedException e) {
            LOG.error("Error closing sync client", e);
        }

    }

    @Override
    public void process(WatchedEvent arg0) {
        LOG.debug("Processing event " + arg0.getPath());
        LOG.debug("Processing event type " + arg0.getType().toString());

    }

    public ZooKeeper getZK() {
        return this.zk;
    }

}