zad1

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package values;
import java.util.concurrent.Semaphore;
/**
 *
 * @author Rau7
 */
public class FirstValue {
    private static int A = 0;
    private static int B = 0;
    private static int C = 3;
    private static final int SLEEP = 1;
    //declare all necessary semaphores
    //private static final Semaphore NONAME = new Semaphore(1, true);
    private static final Semaphore a1 = new Semaphore(0, true);
    private static final Semaphore a2 = new Semaphore(1, true);
    private static final Semaphore a3 = new Semaphore(0, true);
    private static final Semaphore a4 = new Semaphore(0, true);
    public static void main(String[] args) {
        new P2().start();
        new P1().start();
        new P3().start();
        new P4().start();
        //Tutaj suma ma być równa 16
        /*
        Z wątku P2 wykonuję tylko B=B+C - ten startuje jako pierwszy
        Z wątku P1 wykonuję tylko A=10
        Suma 10+3+3 = 16
        Z wątku P4 wyswietlam wynik

        zwalniam pozostałe aktywne wątki, żeby nie "wisiały"
         */
    }
    private static final class P1 extends Thread {
        @Override
        public void run() {
            try {
                Thread.sleep(SLEEP);
                System.out.println("Thread P1 is running...");
                a1.acquire();//czekam na zezwolenie z wątku P1
                A = 10;
                a4.release();//zwalniam wątek P4 (drukowanie)
                a1.acquire();//i blokuję siebie przed wykonaniem kolejnych instrukcji
                B = B + 5;
                C = C + A;
                Thread.sleep(SLEEP);
                System.out.println("Thread P1 is done...");
            } catch (InterruptedException ex) {
                System.out.println("Ooops...");
                Thread.currentThread().interrupt();
                throw new RuntimeException(ex);
            }
        }
    }
    private static final class P2 extends Thread {
        @Override
        public void run() {
            try {
                Thread.sleep(SLEEP);
                System.out.println("Thread P2 is running...");
                B = B + C;
                a1.release();//zwalniam wątek P1
                a2.acquire();//blokuję siebie
                A = A + B;
                Thread.sleep(SLEEP);
                System.out.println("Thread P2 is done...");
            } catch (InterruptedException ex) {
                System.out.println("Ooops...");
                Thread.currentThread().interrupt();
                throw new RuntimeException(ex);
            }
        }
    }
    private static final class P3 extends Thread {
        @Override
        public void run() {
            try {
                Thread.sleep(SLEEP);
                System.out.println("Thread P3 is running...");
                a3.acquire();//czekam na zezwolenie
                C = B + 10;
                A = 2 * A;
                B = B + A;
                System.out.println("Thread P3 is done...");
                //Ten wątek kończy ostatni, nikogo nie musi wpuszczać
            } catch (InterruptedException ex) {
                System.out.println("Ooops...");
                Thread.currentThread().interrupt();
                throw new RuntimeException(ex);
            }
        }
    }
    private static final class P4 extends Thread {
        @Override
        public void run() {
            try {
                a4.acquire();
                System.out.println("Thread 4 is running");
                Thread.sleep(SLEEP);
                System.out.println("Sum result: " + A + " + " + B + " + " + C + " = " + (A + B + C));
                Thread.sleep(SLEEP);
                System.out.println("Thread P4 is done...");
                //Właściwie trzeba by puścić oczekujące wątki
                a1.release();
                a3.release();
            } catch (InterruptedException ex) {
                System.out.println("Ooops...");
                Thread.currentThread().interrupt();
                throw new RuntimeException(ex);
            }
        }
    }
}