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