/* * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt). * * The MIT License * Copyright © 2014-2022 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. * *

In this example, we create a new Lockable object with the SwordOfAragorn implementation of it. * Afterward 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. * */ @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 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(); } } }