/* An example to demonstrate rendez-vous mechanismus
 implemented in Java. 
 
 It implements a ClientServer that receives a parameter from another
 ClientServer object, increments it and passes it to another 
 ClientServer object. This classe can run in normal mode, or in main mode.
 It runs in main mode when its the thread that first receives the parameter
 from the main programs, and initiates the cycle passing it to the next thread. 

 It implements main program that shoul be started :
 java Program nThreads nIterations Parameter 
 where:
  nThreads is the number of ClientServer threads
  nIterations is the number of times that the cicle will be run
  Parameter is the parameter to be passed to the main Thread  */

class ClientServer extends Thread { //thread
    ClientServer pred, suc;

    private Entry e;

    int parameter, n;

    boolean main = false;

    //Normal constructor
    ClientServer(int n) {
        e = new Entry();
        this.n = n;
    }

    //Constructor for main thread
    ClientServer(int n, int parameter) {
        e = new Entry();
        this.n = n;
        main = true;
        this.parameter=parameter;
    }

    void setSuccessor(ClientServer suc) {
        this.suc = suc;
    }

    //entry procedure
    synchronized void entry_1(int n) {
        e.call_entry();
        parameter = n;
        e.release_entry();
        
    }

    public void run() {
        
        //for main thread
        if (main) {
            int originalParameter = parameter;
            for (int i = 0; i < n; i++) {
                suc.entry_1(originalParameter);
                e.accept_entry();
                System.out.println("Iteration " + i
                        + " :Main thread received parameter " + parameter);
            }
        } 
        
        //for other threads
        else {
            for (int i = 0; i < n; i++) {
                e.accept_entry();
                System.out.println("Iteration " + i +": "+ this.getName() + " received parameter " + parameter);
                parameter++;
                suc.entry_1(parameter);
            }
        }
    }
}

public class Example2 {
    public static void main(String[] argv) {
        int nIterations = 0, param = 0, nThreads = 0;

        if (argv.length == 3) { //checking number of arguments
            try { //trying convert string to int
                nThreads = Integer.valueOf(argv[0]).intValue();
                nIterations = Integer.valueOf(argv[1]).intValue();
                param = Integer.valueOf(argv[2]).intValue();

            } catch (NumberFormatException e) {
                System.out.println("Invalid number format!");
            }

            if (nIterations > 0 && nThreads > 0) {

                ClientServer[] array = new ClientServer[nThreads];

                //Create the objects
                array[0] = new ClientServer(nIterations, param);
                for (int i = 1; i < nThreads; i++) {
                    array[i] = new ClientServer(nIterations);
                }

                //Set the successors
                array[nThreads-1].setSuccessor(array[0]);
                for (int i = 0; i < nThreads - 1; i++) {
                    array[i].setSuccessor(array[i + 1]);
                }

                //Initialize the threads
                for (int i = 0; i <nThreads ; i++) {
                    array[i].start();
                }

                try {

                    for (int i = 0; i < nThreads; i++) {
                        array[i].join();
                    }
                } catch (InterruptedException e) {
                }
            } else {
                System.out.println("nThreads and nIterations must be greater than 0!");
            }
        } else {
            System.out.println("Parameters: nThreads nIterations Parameter");

        }
    }
}