commonstate.java

pastry 协议在peersim下的仿真环境。测试无误。在eclipse下打开源文件夹为工程即可使用和做仿真实验。

/*
 * 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.core;

import peersim.config.*;
import peersim.util.*;

/**
 * This is the common state of the simulation all objects see.
 * Static singleton. One of its purposes is
 * simplification of parameter structures and increasing efficiency by putting
 * state information here instead of passing parameters.
 *<p>
 * <em>The set methods should not be used by applications</em>,
 * they are for system
 * components. Use them only if you know exactly what you are doing, e.g.
 * if you are so advanced that you can write your own simulation engine.
 * Ideally, they should not be visible, but due to the lack of more
 * flexibility in java access rights, we are forced to make them public.
 */
public class CommonState
{

//======================= constants ===============================
//=================================================================

/**
* Constant that can be used as a value of simulation phase.
* It means that the simulation has finished.
* @see #getPhase
*/
public static final int POST_SIMULATION = 1;

/**
* Constant that can be used as a value of simulation phase.
* It means that the simulation phase information has not been set (unknown).
* @see #getPhase
*/
public static final int PHASE_UNKNOWN = 0;

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

/**
 * Current time. Note that this value is simulator independent, all simulation
 * models have a notion related to time. For example, in the cycle based model,
 * the cycle id gives time, while in even driven simulations there is a more
 * realistic notion of time.
 */
private static long time = 0;

/**
 * The maximal value {@link #time} can ever take.
 */
private static long endtime = -1;

/**
 * Number of used bits in the long representation of time, calculated
 * based on the endtime.
 */
private static int toshift = -1;

/**
 * Information about where exactly the simulation is.
 */
private static int phase = PHASE_UNKNOWN;

/**
 * The current pid.
 */
private static int pid;

/**
 * The current node.
 */
private static Node node;

/**
* This source of randomness should be used by all components.
* This field is public because it doesn't matter if it changes
* during an experiment (although it shouldn't) until no other sources of
* randomness are used within the system. Besides, we can save the cost
* of calling a wrapper method, which is important because this is needed
* very often.
*/
public static ExtendedRandom r = null;


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

/**
* Configuration parameter used to define which random generator
* class should be used. If not specified, the default implementation
* {@link ExtendedRandom} is used. User-specified random generators 
* must extend class {@link ExtendedRandom}. 
* @config
*/
public static final String PAR_RANDOM = "random";

/**
* Configuration parameter used to initialize the random seed.
* If it is not specified the current time is used.
* @config
*/
public static final String PAR_SEED = "random.seed";


/**
* Initializes the field {@link r} according to the configuration.
* Assumes that the configuration is already
* loaded.
*/
static {
	
	long seed =
		Configuration.getLong(PAR_SEED,System.currentTimeMillis());
	initializeRandom(seed);
}


/** Does nothing. To avoid construction but allow extension. */
protected CommonState() {}

// ======================= methods =================================
// =================================================================


/**
 * Returns current time. In event-driven simulations, returns the current
 * time (a long-value).
 * In cycle-driven simulations, returns the current cycle (a long that
 * can safely be cast into an integer).
 */
public static long getTime()
{
	return time;
}

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

/**
 * Returns current time in integer format. The purpose is to enhance the
 * performance of protocols (ints are smaller and faster) when absolute
 * precision is not required. It assumes that endtime has been set via
 * {@link #setEndTime} by the simulation engine. It uses the endtime for
 * the optimal mapping to get the maximal precision.
 * In particular, in the cycle
 * based model, time is the same as cycle which can be safely cast into
 * integer, so no precision is lost.
 */
public static int getIntTime()
{
	return (int)(time>>toshift);
}

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

/**
 * Sets the current time. 
 */
public static void setTime(long t)
{
	time = t;
}

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

/**
 * Returns endtime.
 * It is the maximal value {@link #getTime} ever returns. If it's negative, it
 * means the endtime is not known.
 */
public static long getEndTime()
{
	return endtime;
}

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

/**
 * Sets the endtime. 
 */
public static void setEndTime(long t)
{
	if( endtime >= 0 )
		throw new RuntimeException("You can set endtime only once");
	if( t < 0 )
		throw new RuntimeException("No negative values are allowed");
		
	endtime = t;
	toshift = 32-Long.numberOfLeadingZeros(t);
	if( toshift<0 ) toshift = 0;
}

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

/**
 * Returns the simulation phase. Currently the following phases are
 * understood.
 * <ul>
 * <li>{@link #PHASE_UNKNOWN} phase is unknown</li>
 * <li>{@link #POST_SIMULATION} the simulation is completed</li>
 * </ul>
 */
public static int getPhase()
{
	return phase;
}

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

public static void setPhase(int p)
{
	phase = p;
}

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

/**
* Returns the current protocol identifier. In other words, control is
* held by the indicated protocol on node {@link #getNode}.
*/
public static int getPid()
{
	return pid;
}

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

/** Sets the current protocol identifier.*/
public static void setPid(int p)
{
	pid = p;
}

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

/**
 * Returns the current node. When a protocol is executing, it is the node
 * hosting the protocol.
 */
public static Node getNode()
{
	return node;
}

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

/** Sets the current node */
public static void setNode(Node n)
{
	node = n;
}

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

public static void initializeRandom(long seed)
{
	if (r == null) {
		r = (ExtendedRandom) Configuration.getInstance(PAR_RANDOM, new ExtendedRandom(seed));
	}
	r.setSeed(seed);
}

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

/*
public static void main(String pars[]) {
	
	setEndTime(Long.parseLong(pars[0]));
	setTime(Long.parseLong(pars[1]));
	System.err.println(getTime()+" "+getIntTime());
}
*/
}