使用TDD驱除线程安全代码 [英] Using TDD to drive out thread-safe code

问题描述

利用TDD驱出线程安全代码的好方法是什么?例如，假设我有一个工厂方法，该方法利用惰性初始化仅创建一个类的实例，然后将其返回:

What's a good way to leverage TDD to drive out thread-safe code? For example, say I have a factory method that utilizes lazy initialization to create only one instance of a class, and return it thereafter:

private TextLineEncoder textLineEncoder;
...
public ProtocolEncoder getEncoder() throws Exception {
    if(textLineEncoder == null)
        textLineEncoder = new TextLineEncoder();
    return textLineEncoder;
}

现在，我想以良好的TDD方式编写一个测试，以强制我使此代码成为线程安全的.具体来说，当两个线程同时调用此方法时，我不想创建两个实例并丢弃一个实例.这很容易做到，但是我怎么写一个让我做的测试呢?

Now, I want to write a test in good TDD fashion that forces me to make this code thread-safe. Specifically, when two threads call this method at the same time, I don't want to create two instances and discard one. This is easily done, but how can I write a test that makes me do it?

我在用Java问这个问题，但是答案应该更广泛地适用.

I'm asking this in Java, but the answer should be more broadly applicable.

推荐答案

虽然可能，但很难-可能比其价值还难.已知的解决方案涉及检测被测代码. 此处的极端编程挑战十四" 值得仔细研究.

It's hard, though possible - possibly harder than it's worth. Known solutions involve instrumenting the code under test. The discussion here, "Extreme Programming Challenge Fourteen" is worth sifting through.

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