org.apache.hadoop.corona.ClusterManagerAvailabilityChecker.java Source code

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Here is the source code for org.apache.hadoop.corona.ClusterManagerAvailabilityChecker.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.corona;

import org.apache.hadoop.net.NetUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.thrift.TException;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.transport.TFramedTransport;
import org.apache.thrift.transport.TSocket;

import java.io.IOException;
import java.net.InetSocketAddress;

/**
 * Has helper method(s) related to the availability of the ClusterManager
 */
public class ClusterManagerAvailabilityChecker {
    static final Log LOG = LogFactory.getLog(ClusterManagerAvailabilityChecker.class);

    /**
     * Used for getting a client to the CoronaProxyJobTracker
     * @param conf
     * @return Returns a client to the CPJT
     * @throws IOException
     */
    public static CoronaProxyJobTrackerService.Client getPJTClient(CoronaConf conf) throws IOException {
        InetSocketAddress address = NetUtils.createSocketAddr(conf.getProxyJobTrackerThriftAddress());
        TFramedTransport transport = new TFramedTransport(new TSocket(address.getHostName(), address.getPort()));
        CoronaProxyJobTrackerService.Client client = new CoronaProxyJobTrackerService.Client(
                new TBinaryProtocol(transport));
        try {
            transport.open();
        } catch (TException e) {
            LOG.info("Transport Exception: ", e);
        }
        return client;
    }

    /**
     * This helper method simply polls the ProxyJobTracker if and until the
     * clusterManagerSafeMode flag is set there.
     * @param conf
     * @throws IOException
     */
    public static void waitWhileClusterManagerInSafeMode(CoronaConf conf) throws IOException {

        CoronaProxyJobTrackerService.Client pjtClient = getPJTClient(conf);
        while (true) {
            try {
                // If this condition holds true, then two things can happen:
                // 1. The CM was never in Safe Mode
                // 2. CM was in Safe Mode, just before we made this method call, and
                //    came out of Safe Mode before the RPC call.
                if (!pjtClient.getClusterManagerSafeModeFlag()) {
                    break;
                }

                // If the safe mode flag is indeed set
                LOG.info("Safe mode flag is set on the ProxyJobTracker");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    throw new IOException(e);
                }
            } catch (TException e) {
                throw new IOException("Could not check the safe mode flag on the ProxyJobTracker", e);
            }
        }
    }
}