package concurrent;

import java.util.concurrent.*;

public class ConcurrentSemaphore extends Thread {

Semaphore sem;

String threadName;

public ConcurrentSemaphore(Semaphore sem, String threadName) {

super(threadName);

this.sem = sem;

this.threadName = threadName;

}

@Override

public void run() {

System.out.println(threadName + " is waiting for a permit.");

try {

sem.acquire();

} catch (Exception e) {

e.printStackTrace();

}

System.out.println(threadName + " gets a permit.");

for(int i = 0; i < 2; i++) {

boolean b =sem.hasQueuedThreads();

if(b) {

System.out.println("Length of Queue: " + sem.getQueueLength());

}

try {

Thread.sleep(100);

} catch(Exception e) {

e.printStackTrace();

}

}

System.out.println(threadName + " releases the permit.");

sem.release();

}

public static void main(String[] args) {

Semaphore sem = new Semaphore(3, true);

System.out.println("Is fairness enabled: " + sem.isFair());

sem.tryAcquire(2);

System.out.println("Avaialable permits: " + sem.availablePermits());

System.out.println("Number of permits drain by Main thread: " +sem.drainPermits());

sem.release(1);

ConcurrentSemaphore mt1 = new ConcurrentSemaphore(sem, "A");

ConcurrentSemaphore mt2 = new ConcurrentSemaphore(sem, "B");

mt1.start();

mt2.start();

System.out.println(sem.toString());

try {

mt1.join();

mt2.join();

} catch (Exception e) {

e.printStackTrace();

}

}

}