starni.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.core.*;
import peersim.config.Configuration;

/**
 * Initializes a node's neighbor list with a fixed center.
 */
public class StarNI implements NodeInitializer {


// ========================= fields =================================
// ==================================================================


/**
 * The protocol to operate on.
 * @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";

/**
 * The protocol we want to wire
 */
protected final int pid;

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

/**
 * Used as center: nodes will link to this node.
 */
protected Node center = null;


// ==================== initialization ==============================
//===================================================================


public StarNI(String prefix) {

	pid = Configuration.getPid(prefix+"."+PAR_PROT);
	pack = Configuration.contains(prefix+"."+PAR_PACK);
}


// ===================== public methods ==============================
// ===================================================================


/**
 * Adds a link to a fixed node, the center. This fixed node remains the same
 * throughout consecutive calls to this method. If the center fails in the
 * meantime, a new one is chosen so care should be taken. The center is the
 * first node that is not down (starting from node 0, 1, etc)
 * at the time of the first call to the function. When a new center needs to
 * be chosen (the current one is down), the new center is again the first
 * one which is up. If no nodes are up, the node with the last index is set
 * as center, and selection of a new center is always attempted when this
 * method is called again.
 */
public void initialize(Node n) {
	
	if( Network.size() == 0 ) return;
	
	for(int i=0; (center==null || !center.isUp()) && i<Network.size(); ++i)
		center=Network.get(i);
	
	((Linkable)n.getProtocol(pid)).addNeighbor(center);
	
	if(pack)
	{
		((Linkable)n.getProtocol(pid)).pack();
	}
}

}