05
Mar

Producer Consumer queue mediator

Producer Consumer queue mediator :
==================================

Step 1: Definition of Consumer / Producer which executes common mediator's get

class Consumer extends Thread {
	private CubbyHole cubbyhole;
	private int number;

	public Consumer(CubbyHole c, int number) {
		cubbyhole = c;
		this.number = number;
	}

	public void run() {
		int value = 0;
		for (int i = 0; i < 10; i++) {
			value = cubbyhole.get();
			System.out.println("Consumer #" + this.number + " got: " + value);
		}
	}
}



class Producer extends Thread {
	private CubbyHole cubbyhole;
	private int number;

	public Producer(CubbyHole c, int number) {
		cubbyhole = c;
		this.number = number;
	}

	public void run() {
		for (int i = 0; i < 10; i++) {
			cubbyhole.put(i);
			System.out.println("Producer #" + this.number + " put: " + i);
			try {
				sleep((int) (Math.random() * 100));
			} catch (InterruptedException e) {
			}
		}
	}
}



Step 2: Define queue which acts as mediator between Consumer and Producer

class CubbyHole {
	private int contents;
	private boolean available = false;

	public synchronized int get() {
		while (available == false) {
			try {
				wait();
			} catch (InterruptedException e) {
			}
		}
		available = false;
		notifyAll();
		return contents;
	}

	public synchronized void put(int value) {
		while (available == true) {
			try {
				wait();
			} catch (InterruptedException e) {
			}
		}
		contents = value;
		available = true;
		notifyAll();
	}
}




Step 3:  Client for Producer/Consumer

package procon;

public class ProducerConsumerTest {
	public static void main(String[] args) {
		CubbyHole c = new CubbyHole();
		Producer p1 = new Producer(c, 1);
		Consumer c1 = new Consumer(c, 1);
		p1.start();
		c1.start();
	}
}



Output:

Consumer #1 got: 0
Producer #1 put: 0
Producer #1 put: 1
Consumer #1 got: 1
Producer #1 put: 2
Consumer #1 got: 2
Producer #1 put: 3
Consumer #1 got: 3
Producer #1 put: 4
Consumer #1 got: 4
Producer #1 put: 5
Consumer #1 got: 5
Producer #1 put: 6
Consumer #1 got: 6
Consumer #1 got: 7
Producer #1 put: 7
Producer #1 put: 8
Consumer #1 got: 8
Producer #1 put: 9
Consumer #1 got: 9