101 lines
3.9 KiB
Java
101 lines
3.9 KiB
Java
/*
|
|
* The MIT License
|
|
* Copyright © 2014-2021 Ilkka Seppälä
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
|
|
package com.iluwatar.lockableobject;
|
|
|
|
import com.iluwatar.lockableobject.domain.Creature;
|
|
import com.iluwatar.lockableobject.domain.Elf;
|
|
import com.iluwatar.lockableobject.domain.Feind;
|
|
import com.iluwatar.lockableobject.domain.Human;
|
|
import com.iluwatar.lockableobject.domain.Orc;
|
|
import java.util.ArrayList;
|
|
import java.util.List;
|
|
import java.util.concurrent.ExecutorService;
|
|
import java.util.concurrent.Executors;
|
|
import java.util.concurrent.TimeUnit;
|
|
import lombok.extern.slf4j.Slf4j;
|
|
|
|
/**
|
|
* The Lockable Object pattern is a concurrency pattern. Instead of using the "synchronized" word
|
|
* upon the methods to be synchronized, the object which implements the Lockable interface handles
|
|
* the request.
|
|
*
|
|
* <p>In this example, we create a new Lockable object with the SwordOfAragorn implementation of it.
|
|
* Afterwards we create 6 Creatures with the Elf, Orc and Human implementations and assign them each
|
|
* to a Fiend object and the Sword is the target object. Because there is only one Sword and it uses
|
|
* the Lockable Object pattern, only one creature can hold the sword at a given time. When the sword
|
|
* is locked, any other alive Fiends will try to lock, which will result in a race to lock the
|
|
* sword.
|
|
*
|
|
* @author Noam Greenshtain
|
|
*/
|
|
@Slf4j
|
|
public class App implements Runnable {
|
|
|
|
private static final int WAIT_TIME = 3;
|
|
private static final int WORKERS = 2;
|
|
private static final int MULTIPLICATION_FACTOR = 3;
|
|
|
|
/**
|
|
* main method.
|
|
*
|
|
* @param args as arguments for the main method.
|
|
*/
|
|
public static void main(String[] args) {
|
|
var app = new App();
|
|
app.run();
|
|
}
|
|
|
|
@Override
|
|
public void run() {
|
|
// The target object for this example.
|
|
var sword = new SwordOfAragorn();
|
|
// Creation of creatures.
|
|
List<Creature> creatures = new ArrayList<>();
|
|
for (var i = 0; i < WORKERS; i++) {
|
|
creatures.add(new Elf(String.format("Elf %s", i)));
|
|
creatures.add(new Orc(String.format("Orc %s", i)));
|
|
creatures.add(new Human(String.format("Human %s", i)));
|
|
}
|
|
int totalFiends = WORKERS * MULTIPLICATION_FACTOR;
|
|
ExecutorService service = Executors.newFixedThreadPool(totalFiends);
|
|
// Attach every creature and the sword is a Fiend to fight for the sword.
|
|
for (var i = 0; i < totalFiends; i = i + MULTIPLICATION_FACTOR) {
|
|
service.submit(new Feind(creatures.get(i), sword));
|
|
service.submit(new Feind(creatures.get(i + 1), sword));
|
|
service.submit(new Feind(creatures.get(i + 2), sword));
|
|
}
|
|
// Wait for program to terminate.
|
|
try {
|
|
if (!service.awaitTermination(WAIT_TIME, TimeUnit.SECONDS)) {
|
|
LOGGER.info("The master of the sword is now {}.", sword.getLocker().getName());
|
|
}
|
|
} catch (InterruptedException e) {
|
|
LOGGER.error(e.getMessage());
|
|
Thread.currentThread().interrupt();
|
|
} finally {
|
|
service.shutdown();
|
|
}
|
|
}
|
|
}
|