org.apache.hadoop.hdfs.conf.NameSpaceAddressManager.java Source code

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Here is the source code for org.apache.hadoop.hdfs.conf.NameSpaceAddressManager.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.hadoop.hdfs.conf;

import java.io.Closeable;
import java.io.IOException;
import java.net.UnknownHostException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.AvatarZooKeeperClient;
import org.apache.hadoop.hdfs.protocol.AvatarConstants.InstanceId;
import org.apache.zookeeper.KeeperException;

/**
 * The purpose of this class is to abstract out Zookeeper status
 * and configuration details from Avatar classes.
 * 
 */
public abstract class NameSpaceAddressManager implements Closeable {
    /** The configuration object for which this serves as a wrapper for */
    protected Configurable confSrc;
    private static final Log LOG = LogFactory.getLog(NameSpaceAddressManager.class.getName());
    protected NameNodeAddress nodeZero;
    protected NameNodeAddress nodeOne;
    protected NameNodeAddress primaryNode;
    protected NameNodeAddress standbyNode;

    /** The ZookeeperClient used to determine which AvatarNode is primary */
    protected AvatarZooKeeperClient zkClient;

    protected NameSpaceAddressManager(Configurable parent) {
        setConfSource(parent);
    }

    /**
     * The purpose of this method is to update in memory references to primary 
     * and standby. Please override this method and do the zookeeper specific 
     * logic in the method and call this method on successful zookeeper write.
     */
    public void setPrimary(InstanceId ofPrimary) throws IOException {
        if (ofPrimary == null) {
            // failover in progress
            primaryNode = null;
            standbyNode = null;
            return;
        }
        switch (ofPrimary) {
        case NODEZERO:
            primaryNode = getNodeZero();
            standbyNode = getNodeOne();
        case NODEONE:
            primaryNode = getNodeOne();
            standbyNode = getNodeZero();
        }
    }

    public boolean isFailoverInProgress() {
        return getPrimary() == null || getStandby() == null;
    }

    /**
     * Reads all the configuration related information from the
     * Zookeeper and updates the in memory references (instance variables)
     *  accordingly.
     */
    public abstract void refreshZookeeperInfo() throws IOException, KeeperException, InterruptedException;

    /**
     * Sets the backing configuration source
     */
    public void setConfSource(Configurable src) {
        validateConfigFile(src.getConf());
        confSrc = src;
        zkClient = new AvatarZooKeeperClient(confSrc.getConf(), null, true);
    }

    public void finalize() throws IOException {
        close();
    }

    public void close() {
        if (zkClient != null) {
            try {
                zkClient.shutdown();
            } catch (InterruptedException e) {
                LOG.warn(e);
            }
        }
    }

    /**
     * Validates the configuration file. Called at startup to fail fast and avoid
     * errors while running.
     */
    public abstract void validateConfigFile(Configuration parent);

    public NameNodeAddress getPrimary() {
        return primaryNode;
    }

    public NameNodeAddress getStandby() {
        return standbyNode;
    }

    public NameNodeAddress getNodeZero() {
        return nodeZero;
    }

    public NameNodeAddress getNodeOne() {
        return nodeOne;
    }

    public abstract String getTxidPath() throws UnknownHostException;

    public abstract String getSsidPath() throws UnknownHostException;
}