edu.umass.cs.msocket.proxy.GnsTimerKeepalive.java Source code

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Here is the source code for edu.umass.cs.msocket.proxy.GnsTimerKeepalive.java

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/*******************************************************************************
 *
 * Mobility First - mSocket library
 * Copyright (C) 2013, 2014 - University of Massachusetts Amherst
 * Contact: arun@cs.umass.edu
 *
 * Licensed 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. 
 *
 * Initial developer(s): Arun Venkataramani, Aditya Yadav, Emmanuel Cecchet.
 * Contributor(s): ______________________.
 *
 *******************************************************************************/

package edu.umass.cs.msocket.proxy;

import java.util.logging.Level;
import java.util.logging.Logger;

import org.json.JSONArray;

import edu.umass.cs.gns.client.GnsProtocol.AccessType;
import edu.umass.cs.gns.client.GuidEntry;
import edu.umass.cs.gns.client.UniversalGnsClient;
import edu.umass.cs.msocket.common.GnsConstants;
import edu.umass.cs.msocket.gns.GnsCredentials;

/**
 * This class defines a GnsTimerKeepalive
 * 
 * @author <a href="mailto:cecchet@cs.umass.edu">Emmanuel Cecchet</a>
 * @version 1.0
 */
public class GnsTimerKeepalive extends Thread {

    private GnsCredentials gnsCredentials;
    private GuidEntry guid;
    private int publishFrequency;
    private boolean killed = false;
    private static final Logger logger = Logger.getLogger("KeepAliveTimer");

    /**
     * Creates a new <code>GnsTimerKeepalive</code> object
     * 
     * @param gnsCredentials
     * @param myGuid
     * @param publishFrequency
     * @throws Exception if a GNS error occurs
     */
    public GnsTimerKeepalive(GnsCredentials gnsCredentials, GuidEntry myGuid, int publishFrequency)
            throws Exception {
        this.gnsCredentials = gnsCredentials;
        this.guid = myGuid;
        this.publishFrequency = publishFrequency;
        logger.fine("Publishing start time");
        final long now = System.currentTimeMillis();
        UniversalGnsClient gnsClient = gnsCredentials.getGnsClient();
        gnsClient.fieldReplaceOrCreate(myGuid.getGuid(), GnsConstants.START_TIME, new JSONArray().put(now), myGuid);
        gnsClient.aclAdd(AccessType.READ_WHITELIST, myGuid, GnsConstants.START_TIME, null);
        gnsClient.fieldReplaceOrCreate(myGuid.getGuid(), GnsConstants.TIME_REFRESH_INTERVAL,
                new JSONArray().put(publishFrequency), myGuid);
        gnsClient.aclAdd(AccessType.READ_WHITELIST, myGuid, GnsConstants.TIME_REFRESH_INTERVAL, null);
        gnsClient.fieldReplaceOrCreate(guid.getGuid(), GnsConstants.CURRENT_TIME, new JSONArray().put(now), myGuid);
        gnsClient.aclAdd(AccessType.READ_WHITELIST, myGuid, GnsConstants.CURRENT_TIME, null);
        logger.setLevel(Level.FINE);
    }

    /**
     * Call this method to terminate the thread
     */
    public void killIt() {
        killed = true;
    }

    /**
     * @see java.lang.Thread#run()
     */
    @Override
    public void run() {
        long last = System.currentTimeMillis();
        while (!killed) {
            long sleepFor = last + publishFrequency - System.currentTimeMillis();
            if (sleepFor > 0)
                try {
                    Thread.sleep(sleepFor);
                } catch (InterruptedException ignore) {
                }

            last = System.currentTimeMillis();
            try {
                gnsCredentials.getGnsClient().fieldReplace(guid.getGuid(), GnsConstants.CURRENT_TIME,
                        new JSONArray().put(last), guid);
                logger.fine("Updated current time to " + last);
            } catch (Exception e) {
                logger.log(Level.WARNING, "Failed to update CURRENT_TIME with " + last, e);
            }
        }
    }

}