AtomicInteger 的实际用途

问题描述

我有点理解 AtomicInteger 和其他 Atomic 变量允许并发访问.在什么情况下通常使用这个类?

I sort of understand that AtomicInteger and other Atomic variables allow concurrent accesses. In what cases is this class typically used though?

推荐答案

AtomicInteger 主要有两个用途:

• 作为一个原子计数器(incrementAndGet()等)，可以被多个线程同时使用

• As an atomic counter (incrementAndGet(), etc) that can be used by many threads concurrently

作为支持 compare-and-swap 指令的原语(compareAndSet()) 来实现非阻塞算法.

As a primitive that supports compare-and-swap instruction (compareAndSet()) to implement non-blocking algorithms.

以下是来自 的非阻塞随机数生成器示例Brian Göetz 的 Java 并发实践:

public class AtomicPseudoRandom extends PseudoRandom {
    private AtomicInteger seed;
    AtomicPseudoRandom(int seed) {
        this.seed = new AtomicInteger(seed);
    }

    public int nextInt(int n) {
        while (true) {
            int s = seed.get();
            int nextSeed = calculateNext(s);
            if (seed.compareAndSet(s, nextSeed)) {
                int remainder = s % n;
                return remainder > 0 ? remainder : remainder + n;
            }
        }
    }
    ...
}

如您所见，它的工作方式与 incrementAndGet() 基本相同，但执行任意计算(calculateNext())而不是增量(并处理返回前的结果).

As you can see, it basically works almost the same way as incrementAndGet(), but performs arbitrary calculation (calculateNext()) instead of increment (and processes the result before return).

这篇关于AtomicInteger 的实际用途的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！