wiregraph.java

peersim仿真chord协议的测试过的环境

/*
 * 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 peersim.dynamics;

import peersim.graph.Graph;
import peersim.core.*;
import peersim.config.Configuration;

/**
 * This class is the superclass of classes that
 * takes a {@link Linkable} protocol or a graph and add edges that define a
 * certain topology.
 * Note that no connections are removed, they are only added. So it can be used
 * in combination with other initializers.
 */
public abstract class WireGraph implements Control
{

// --------------------------------------------------------------------------
// Parameters
// --------------------------------------------------------------------------

/**
 * The {@link Linkable} protocol to operate on. If it is not specified,
 * then operates on {@link #g}. If {@link #g} is null, {@link #execute} throws
 * an Exception. Note that if {@link #g} is set, it will be used irrespective
 * of the setting of the protocol in this field.
 * @config
 */
private static final String PAR_PROT = "protocol";

/**
 * If this config property is defined, method {@link Linkable#pack()} is 
 * invoked on the specified protocol at the end of the wiring phase. 
 * Default to false.
 * @config
 */
private static final String PAR_PACK = "pack";

/**
 * If set, the generated graph is undirected. In other words, for each link
 * (i,j) a link (j,i) will also be added. Defaults to false.
 * @config
 */
private static final String PAR_UNDIR = "undir";

/**
* Alias for {@value #PAR_UNDIR}.
* @config
*/
private static final String PAR_UNDIR_ALT = "undirected";

// --------------------------------------------------------------------------
// Fields
// --------------------------------------------------------------------------

/**
 * The protocol we want to wire. It is negative if no protocol was set
 * (in that case, a graph must be specified, see {@link #g}).
 */
protected final int pid;

/** If true, method pack() is invoked on the initialized protocol */
private final boolean pack;

/** If true, edges are added in an undirected fashion.*/
public final boolean undir;

/**
* If set (not null), this is the graph to wire. If null, the current overlay
* is wired each time {@link #execute} is called, as specified by {@value
* #PAR_PROT}.
*/
public Graph g=null;

// --------------------------------------------------------------------------
// Initialization
// --------------------------------------------------------------------------

/**
 * Standard constructor that reads the configuration parameters. Normally
 * invoked by the simulation engine.
 * @param prefix
 *          the configuration prefix for this class
 */
protected WireGraph(String prefix) {

	if( Configuration.contains(prefix + "." + PAR_PROT) )
		pid = Configuration.getPid(prefix + "." + PAR_PROT);
	else
		pid = -10;
	pack = Configuration.contains(prefix + "." + PAR_PACK);
	undir = (Configuration.contains(prefix + "." + PAR_UNDIR) |
		Configuration.contains(prefix + "." + PAR_UNDIR_ALT));
}


//--------------------------------------------------------------------------
//Public methods
//--------------------------------------------------------------------------

/**
* Calls method {@link #wire} with the graph {@link #g},
* or if null, on the overlay specified by the protocol given by config
* parameter {@value #PAR_PROT}. If neither {@link #g}, nor {@value #PAR_PROT}
* is set, throws a RuntimException.
*/
public final boolean execute() {

	Graph gr;
	if(g==null && pid==-10)
	{
		throw new RuntimeException(
			"Neither a protocol, nor a graph is specified.");
	}
	if(g==null) gr = new OverlayGraph(pid,!undir);
	else gr=g;

	if(gr.size()==0) return false;
	wire(gr);
	
	if( g==null && pack)
	{
		int size = Network.size();
		for (int i = 0; i < size; i++)
		{
			Linkable link =
				(Linkable) Network.get(i).getProtocol(pid);
			link.pack();
		}
	}
	return false;
}

//--------------------------------------------------------------------------

/** The method that should wire (add edges to) the given graph. Has to
* be implemented by extending classes */
public abstract void wire(Graph g);

}