70 lines
2.6 KiB
Java
70 lines
2.6 KiB
Java
/**
|
|
* The MIT License
|
|
* Copyright (c) 2014 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.doublechecked.locking;
|
|
|
|
import org.slf4j.Logger;
|
|
import org.slf4j.LoggerFactory;
|
|
|
|
import java.util.concurrent.ExecutorService;
|
|
import java.util.concurrent.Executors;
|
|
import java.util.concurrent.TimeUnit;
|
|
|
|
/**
|
|
*
|
|
* Double Checked Locking is a concurrency design pattern used to reduce the overhead of acquiring a
|
|
* lock by first testing the locking criterion (the "lock hint") without actually acquiring the
|
|
* lock. Only if the locking criterion check indicates that locking is required does the actual
|
|
* locking logic proceed.
|
|
* <p>
|
|
* In {@link Inventory} we store the items with a given size. However, we do not store more items
|
|
* than the inventory size. To address concurrent access problems we use double checked locking to
|
|
* add item to inventory. In this method, the thread which gets the lock first adds the item.
|
|
*
|
|
*/
|
|
public class App {
|
|
|
|
private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
|
|
|
|
/**
|
|
* Program entry point
|
|
*
|
|
* @param args command line args
|
|
*/
|
|
public static void main(String[] args) {
|
|
final Inventory inventory = new Inventory(1000);
|
|
ExecutorService executorService = Executors.newFixedThreadPool(3);
|
|
for (int i = 0; i < 3; i++) {
|
|
executorService.execute(() -> {
|
|
while (inventory.addItem(new Item())) {};
|
|
});
|
|
}
|
|
|
|
executorService.shutdown();
|
|
try {
|
|
executorService.awaitTermination(5, TimeUnit.SECONDS);
|
|
} catch (InterruptedException e) {
|
|
LOGGER.error("Error waiting for ExecutorService shutdown");
|
|
}
|
|
}
|
|
}
|