Fibonacci Numbers. Develop an actor program for computing Fibonacci numbers conc

Question

Fibonacci Numbers. Develop an actor program for computing Fibonacci numbers concurrently. Particularly, create an actor which receives a request for a particular Fibonacci number from a client actor. If it is one of the base cases, the actor replies with a message containing the answer; otherwise, it creates the two sub-problems you would normally create in a recursive implementation. It then creates two new (Fibonacci) actors, and hands one sub-problem to each. Once it has received replies from these actors, it adds them to produce its result, and sends it back to the computation's client.

Explanation / Answer

*** Try this code ****

import osl.manager.Actor;
import osl.manager.ActorName;
import osl.manager.RemoteCodeException;
import osl.manager.annotations.message;

/**
* This class represents another implementation of the fibonacci example actor.
* It has the same methods but here the main actor creates two new worker actors
* to perform the sub-calculations.
*
*/
public class FibonacciActor2 extends Actor {

//Number of responses we have received, if we are a worker fib actor
private int numResponses;

//The first response we have received from a child fib actor.
// We save this value until we receive the second response.
// We then send our client the sum of both values.
private int partialResponse;

//The name of the receiving client (if we are a worker fib actor)
private ActorName client;

//The method to invoke on the receiving client (if we are a worker fib actor)
private String meth;

//The default constructor
public FibonacciActor2() {
}

/**
* A constructor which tells us who to send the result when we have
* received all responses. We only use this constructor for building
* the response portion of a fibonacci request. I.e. this constructor
* should normally only be called internally.
*/
public FibonacciActor2(ActorName theClient, String theMeth) {
client = theClient;
meth = theMeth;
numResponses = 0;
}

private long startTime = 0;
private int requestedFibNumber = -1; //default value to show unacceptable

/**
* The boot() method is the initial method to start an Actor program
* This boot method, receives an argument and start the code
*
* @param nthFib
* the nth fibonacci number to be calculated
*/
@message
public void boot(Integer nthFib) throws SecurityException,
RemoteCodeException {
startTime = System.nanoTime();
requestedFibNumber = nthFib;
ActorName root = create(FibonacciActor2.class, self(), "finished");
sendByRef(root, "fib", nthFib);
}

// This method is called only when the final value is calculated
@message
public void finished(Integer finalVal) {
send(stdout, "println", requestedFibNumber + "th Fibonacci number is: "
+ finalVal + " calculated in "
+ ((System.nanoTime() - startTime) / 1000000) + "ms");

}

/**
* This method is called by a client to request a fib computation.
*
* @param currentFib
* indicating which fibonacci number should be computed in this call
* @param client
* the name of the client who is waiting for a
* @param meth
* name of the method to be invoked on the client when finishied
*/
@message
public void fib(Integer currentFib) throws RemoteCodeException {

// We already know the first 2 Fibonacci numbers:
if (currentFib == 0) {
sendByRef(client, meth, 0);
} else if (currentFib < 3) {
sendByRef(client, meth, currentFib-1);
} else {
// Otherwise, create two children to handle the two sub-problems and
//act yourself as the manager to add up their results
ActorName newChild1 = create(FibonacciActor2.class, self(), "result");
sendByRef(newChild1, "fib", currentFib - 1);
ActorName newChild2 = create(FibonacciActor2.class, self(), "result");
sendByRef(newChild2, "fib", currentFib - 2);
}
}

/**
* This method is called from another child actor to pass a partial result.
* We wait until we have two such results, sum them, and return the result
* to our client.
*
* @param currentFib
* the partial result passed from a child fib actor.
*/
@message
public void result(Integer currentFib) {
if (numResponses == 0) {
numResponses++;
partialResponse = currentFib;
} else {
// Send the answer
sendByRef(client, meth, currentFib + partialResponse);
}
}
}

Hope it will help you!!!!!!!!!!!

Thank you!!!!!!!!!!!!!

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