averageobserver.java

peersim最新版1.0.4

/*
 * Copyright (c) 2003-2005 The BISON Project
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

package example.aggregation;

import peersim.config.*;
import peersim.core.*;
import peersim.vector.*;
import peersim.util.IncrementalStats;

/**
 * Print statistics for an average aggregation computation. Statistics printed
 * are defined by {@link IncrementalStats#toString}
 * 
 * @author Alberto Montresor
 * @version $Revision: 1.17 $
 */
public class AverageObserver implements Control {

    // /////////////////////////////////////////////////////////////////////
    // Constants
    // /////////////////////////////////////////////////////////////////////

    /**
     * Config parameter that determines the accuracy for standard deviation
     * before stopping the simulation. If not defined, a negative value is used
     * which makes sure the observer does not stop the simulation
     * 
     * @config
     */
    private static final String PAR_ACCURACY = "accuracy";

    /**
     * The protocol to operate on.
     * 
     * @config
     */
    private static final String PAR_PROT = "protocol";

    // /////////////////////////////////////////////////////////////////////
    // Fields
    // /////////////////////////////////////////////////////////////////////

    /**
     * The name of this observer in the configuration. Initialized by the
     * constructor parameter.
     */
    private final String name;

    /**
     * Accuracy for standard deviation used to stop the simulation; obtained
     * from config property {@link #PAR_ACCURACY}.
     */
    private final double accuracy;

    /** Protocol identifier; obtained from config property {@link #PAR_PROT}. */
    private final int pid;

    // /////////////////////////////////////////////////////////////////////
    // Constructor
    // /////////////////////////////////////////////////////////////////////

    /**
     * Creates a new observer reading configuration parameters.
     */
    public AverageObserver(String name) {
        this.name = name;
        accuracy = Configuration.getDouble(name + "." + PAR_ACCURACY, -1);
        pid = Configuration.getPid(name + "." + PAR_PROT);
    }

    // /////////////////////////////////////////////////////////////////////
    // Methods
    // /////////////////////////////////////////////////////////////////////

    /**
     * Print statistics for an average aggregation computation. Statistics
     * printed are defined by {@link IncrementalStats#toString}. The current
     * timestamp is also printed as a first field.
     * 
     * @return if the standard deviation is less than the given
     *         {@value #PAR_ACCURACY}.
     */
    public boolean execute() {
        long time = peersim.core.CommonState.getTime();

        IncrementalStats is = new IncrementalStats();

        for (int i = 0; i < Network.size(); i++) {

            SingleValue protocol = (SingleValue) Network.get(i)
                    .getProtocol(pid);
            is.add(protocol.getValue());
        }

        /* Printing statistics */
        System.out.println(name + ": " + time + " " + is);

        /* Terminate if accuracy target is reached */
        return (is.getStD() <= accuracy);
    }
}