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How to implement the Binary Exponential Backoff for ContentionLan?? this is the code?
How to implement the Binary Exponential Backoff for ContentionLan??
this is the code?
/**
* Java Network Workbench 2 (JNW2)
* Copyright 2013-2017 Networking and Simulation Laboratory/George Mason University
*
* Implements Binary Exponential Backoff for ContentionLan
*
* @version 2.2.3
*/
package JNW2.interfaces;
import JNW2.*;
import JNW2.links.*;
import JNW2.nodes.*;
import JNW2.stack.*;
import JNW2.utility.*;
/**
* Implements Binary Exponential Backoff for ContentionLan
* @author JMP
*/
public class Backoff
{
private final static int MAX_BACKOFF = 16; // maxmimum times to backoff
private final static int MAX_DOUBLE = 10; // maxmimum times to double slots
private final static int FAIL = -1; // return this after MAX_BACKOFF tries
// instance variable
int backoffCount;
long seed;
private final RandomNumber random;
private final byte interfaceNumber;
private int maxBackoffSlots; // current max range of backoff values
public Backoff(byte lanInterfaceNumber)
{
interfaceNumber = lanInterfaceNumber;
seed = 100*lanInterfaceNumber + 1;
random = new RandomNumber(seed);
backoffCount = 0;
maxBackoffSlots = 0;
}
/**
* Binary exponential backoff algorithm:
* try up to sixteen times
* first 10 tries, return 2^n-1 for nth try
* next 6 tries, return 2^10-1
* after 16 tries, return -1
* @return number of backoff slots
*/
public int binaryExponentialBackoff()
{
// student solution goes below
// and be sure to include your name
// student name:
// **********student solution replaces the next line****************
if(true)return -1;
// ********** endstudent solution **********************************
double rand;
rand = random.getRandomFloat();
// return random int number of slots
return (int)Math.round(rand * maxBackoffSlots);
}
/**
* resets backoff count parameter to zero
*/
public void zeroBackoffCount()
{
backoffCount = 0;
maxBackoffSlots = 0;
}
/**
* returns current backoff count
* @return backoffCount
*/
public int getBackoffCount()
{
return backoffCount;
}
/**
* returns current max backoff slots
* @return maxBackoffSlots
*/
public int getMaxBackoffSlots()
{
return maxBackoffSlots;
}
/**
* tests the basic functions of Backoff
*/
static class BackoffTest
{
public BackoffTest()
{
// setup simulation environment
SimLogger simLogger = SimLogger.getInstance(SimLogger.INFO);
Topology topology = new Topology();
SimulationEngine simEngine = new SimulationEngine(topology);
simEngine.setInstance(simEngine);
// configure network and run test
try
{
// setup LAN and LanInterface where Backoff will exist
int[] lanDataRate = {0,10};
topology.setSubnetDataRate(lanDataRate);
ContentionLan lan = new ContentionLan(1);
Node node = new Node(1, 1, (byte)51, 1);
Stack stack = new Stack(node);
LanInterface lanInterface = new LanInterface(stack, 1, 1, (byte)1);
Backoff backoff = lanInterface.getBackoff();
// test backoff against spec
System.out.println("TRY RANDOM SLOTS MAX SLOTS");
for(int index=1; index<20; ++index)
System.out.println(index + " " +
backoff.binaryExponentialBackoff() + " " +
backoff.getMaxBackoffSlots());
backoff.zeroBackoffCount();
System.out.println("nRESET");
for(int index=1; index<20; ++index)
System.out.println(index + " " +
backoff.binaryExponentialBackoff() + " " +
backoff.getMaxBackoffSlots());
}
catch(Exception e)
{
System.err.println("Exception in BackoffTest:" + e.getMessage());
simLogger.logException(e);
}
}//end BackoffTest() constructor
}// end class BackoffTest
// Test Backoff
public static void main(String[] args)
{
BackoffTest backoffTest;
backoffTest = new BackoffTest();
}// end main()
}// end class Backoff
