95 lines
2.6 KiB
Java
95 lines
2.6 KiB
Java
// lowlevel/Restaurant.java
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// (c)2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// The producer-consumer approach to task cooperation
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import java.util.concurrent.*;
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class Meal {
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private final int orderNum;
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public Meal(int orderNum) { this.orderNum = orderNum; }
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@Override
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public String toString() { return "Meal " + orderNum; }
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}
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class WaitPerson implements Runnable {
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private Restaurant restaurant;
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public WaitPerson(Restaurant r) { restaurant = r; }
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@Override
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public void run() {
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try {
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while(!Thread.interrupted()) {
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synchronized(this) {
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while(restaurant.meal == null)
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wait(); // ... for the chef to produce a meal
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}
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System.out.println(
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"Waitperson got " + restaurant.meal);
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synchronized(restaurant.chef) {
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restaurant.meal = null;
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restaurant.chef.notifyAll(); // Ready for more
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}
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}
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} catch(InterruptedException e) {
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System.out.println("WaitPerson interrupted");
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}
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}
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}
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class Chef implements Runnable {
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private Restaurant restaurant;
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private int count = 0;
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public Chef(Restaurant r) { restaurant = r; }
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@Override
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public void run() {
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try {
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while(!Thread.interrupted()) {
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synchronized(this) {
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while(restaurant.meal != null)
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wait(); // ... for the meal to be taken
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}
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if(++count == 10) {
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System.out.println("Out of food, closing");
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restaurant.exec.shutdownNow();
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}
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System.out.print("Order up! ");
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synchronized(restaurant.waitPerson) {
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restaurant.meal = new Meal(count);
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restaurant.waitPerson.notifyAll();
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}
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TimeUnit.MILLISECONDS.sleep(100);
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}
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} catch(InterruptedException e) {
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System.out.println("Chef interrupted");
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}
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}
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}
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public class Restaurant {
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Meal meal;
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ExecutorService exec = Executors.newCachedThreadPool();
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WaitPerson waitPerson = new WaitPerson(this);
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Chef chef = new Chef(this);
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public Restaurant() {
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exec.execute(chef);
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exec.execute(waitPerson);
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}
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public static void main(String[] args) {
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new Restaurant();
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}
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}
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/* Output:
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Order up! Waitperson got Meal 1
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Order up! Waitperson got Meal 2
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Order up! Waitperson got Meal 3
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Order up! Waitperson got Meal 4
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Order up! Waitperson got Meal 5
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Order up! Waitperson got Meal 6
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Order up! Waitperson got Meal 7
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Order up! Waitperson got Meal 8
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Order up! Waitperson got Meal 9
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Out of food, closing
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Order up! WaitPerson interrupted
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Chef interrupted
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*/
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