为什么不C＃允许空值被锁定？ [英] Why doesn't C# allow a null value to be locked?

问题描述

C＃不允许锁定在一个空值。我想我可以检查值是否为空或不是我锁定它之前，但因为我还没有锁定它的另一个线程可以一起去，使null值！我怎样才能避免这种竞争状态？

C# doesn't allow locking on a null value. I suppose I could check whether the value is null or not before I lock it, but because I haven't locked it another thread could come along and make the value null! How can I avoid this race condition?

推荐答案

锁定上是从来没有空，如：

Lock on a value that is never null, e.g.

Object _lockOnMe = new Object();
Object _iMightBeNull;
public void DoSomeKungFu() {
    if (_iMightBeNull == null) {
        lock (_lockOnMe) {
            if (_iMightBeNull == null) {
                _iMightBeNull = ...  whatever ...;
            }
        }
    }
}

另外要小心，以避免双重检查锁定这个有趣的比赛状态：在双重检查锁定

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