Implement an unlimited working queue

A work queue coordinates the relationship between the producer and the consumer. When a new object is added to the queue, the message is sent to the consumer until the next message arrives in empty.

 

public class WorkQueue {    LinkedList queue = new LinkedList();    // Add work to the work queue    public synchronized void addWork(Object o) {        queue.addLast(o);        notify();    }    // Retrieve work from the work queue; block if the queue is empty    public synchronized Object getWork() throws InterruptedException {        while (queue.isEmpty()) {            wait();        }        return queue.removeFirst();    }}

class Worker extends Thread {    // Special end-of-stream marker. If a worker retrieves    // an Integer that equals this marker, the worker will terminate.    static final Object NO_MORE_WORK = new Object();    WorkQueue q;    Worker(WorkQueue q) {        this.q = q;    }    public void run() {        try {            while (true) {                // Retrieve some work; block if the queue is empty                Object x = q.getWork();                // Terminate if the end-of-stream marker was retrieved                if (x == NO_MORE_WORK) {                    break;                }                // Compute the square of x                int y = ((Integer)x).intValue() * ((Integer)x).intValue();            }        } catch (InterruptedException e) {        }    }}

// Create the work queueWorkQueue queue = new WorkQueue();// Create a set of worker threadsfinal int numWorkers = 2;Worker[] workers = new Worker[numWorkers];for (int i=0; i<workers.length; i++) {    workers[i] = new Worker(queue);    workers[i].start();}// Add some work to the queue; block if the queue is full.// Note that null cannot be added to a blocking queue.for (int i=0; i<100; i++) {    queue.addWork(i);}// Add special end-of-stream markers to terminate the workersfor (int i=0; i<workers.length; i++) {    queue.addWork(Worker.NO_MORE_WORK);}