//Producers consumers relationship.  from p. 300 Schildt
//multiple producers, multiple consumers.
//args: queue_size num_producers randomproduce_range num_consumers randomconsume_range

public class prod_cons {

    static java.util.Random rand;
    static {rand = new java.util.Random(System.currentTimeMillis());}

    public static void main(String[] args) {
	if (args.length != 5) {
	    System.out.println("Usage: prod_cons qSize num_producers "+
			       "prod_random num_consumers cons_random");
	    System.exit(1);
	}
	int qSize = Integer.parseInt(args[0]);
	int num_producers = Integer.parseInt(args[1]);
	int prodrand = Integer.parseInt(args[2]);
	int num_consumers = Integer.parseInt(args[3]);
	int consrand = Integer.parseInt(args[4]);
	Q q = new Q(qSize);
	for (int i=0; i<num_producers; i++)
	    new Producer(q,prodrand);
	for (int i=0; i<num_consumers; i++)
	    new Consumer(q,consrand);
    }
}


class Q {
    private int maxsize;
    private int tail;    //larger number, enqueue 
    private int head;    //trailing number, dequeue

    //not needed for single producer, single consumer case:
    //just wait and notify on this object
    private static class Wait{} //to have an object for producers waiting list
    private Wait producers = new Wait(); //list of waiting producers
    //    private Wait consumers = new Wait(); //list of waiting consumers

    Q (int size) {
	maxsize = size;
    }

    //    synchronized void put() {
    void put() {
	System.out.println("IN PUT");
	while (tail-head == maxsize)    //queue full
	    try {
		System.out.println("Producer waiting...");
		synchronized (producers) {
		    producers.wait();    //wait on producers object
		}
	    } catch (InterruptedException e) {
		System.out.println("Producer interrupted");
	    }
	//instead of synch on method:
	synchronized(this) {
	    tail++;   //enqueue
	}
	System.out.println("after put: head:"+head+"  tail:"+tail+
			   "  Q size:"+(tail-head));
	//synchronized (consumers) {
	//consumers.notify();//notify a consumer, not another producer
	synchronized(this) {
	    notify();//notify a consumer, not another producer
	}
	System.out.println("OUT PUT");
	
    }

    synchronized void get() {
	System.out.println("IN GET");

	while (tail == head)    //queue empty
	    try {
		System.out.println("Consumer waiting...");
		//synchronized (consumers) {
		//consumers.wait();  //wait on consumers list
		wait();  //wait on consumers list
		//}
	    } catch (InterruptedException e) {
		System.out.println("Consumer interrupted");
	    }
	head++;   //dequeue
	System.out.println("after get: head:"+head+"  tail:"+tail+
			   "  Q size:"+(tail-head));
	synchronized (producers) {
	    producers.notify();   //notify a producer, not another consumer
	}
	System.out.println("OUT GET");
    }


}


class Producer implements Runnable {
    static int nextid = 1;

    Q q;
    int randwait;
    int id;

    Producer(Q q, int prodrand) {
	this.q = q;
	this.randwait = prodrand;
	this.id = nextid++;
	System.out.println("Producer "+id+" running");
	new Thread(this,"Producer "+id).start();
    }

    public void run() {
	int worktime;
	while (true) {
	    try {
		worktime = prod_cons.rand.nextInt(randwait);
		System.out.println("Producer "+id+" work: "+worktime);
		Thread.sleep(worktime);
	    } catch (InterruptedException e) {
		System.out.println("Producer "+id+" sleep interrupted");
	    }
	    q.put();
	}
    }
}



class Consumer implements Runnable {
    static int nextid = 1;

    Q q;
    int randwait;
    int id;

    Consumer(Q q, int consrand) {
	this.q = q;
	this.randwait = consrand;
	this.id = nextid++;
	System.out.println("Consumer "+id+" running");
	new Thread(this,"Consumer "+id).start();
    }

    public void run() {
	int worktime;
	while (true) {
	    System.out.println("WANT IN GET ");
	    q.get();
	    try {
		worktime = prod_cons.rand.nextInt(randwait);
		System.out.println("Consumer "+id+" work: "+worktime);
		Thread.sleep(worktime);
	    } catch (InterruptedException e) {
		System.out.println("Consumer "+id+" sleep interrupted");
	    }
	}
    }
}