什么时候我真的需要使用atomic< bool>而不是bool？ [英] When do I really need to use atomic<bool> instead of bool?

问题描述

不是 atomic< bool> 做了一些冗余的工作？我不认为有一个部分修改bool值。那么bool原子性质？我什么时候真的需要使用 atomic< bool> 而不是bool？

Isn't atomic<bool> did some redundant work? I don't think there is a partial modified bool value. So is bool atomic by nature? When do I really need to use atomic<bool> instead of bool?

推荐答案

除非是 std :: atomic * -something，否则C ++中的

否类型是

No type in C++ is "atomic by nature" unless it is an std::atomic*-something. That's because the standard says so.

在实际操作中，发出的操作 std :: atomic< bool> 可能（或可能不）与普通的 bool 相同，但原子是一个更大的概念，具有更广泛的分支（例如对编译器的限制 - ）。此外，一些操作（如否定）在原子操作上重载，以在硬件上创建与非原子变量的本地非原子读 - 修改 - 写入序列明显不同的指令。

In practice, the actual hardware instructions that are emitted to manipulate an std::atomic<bool> may (or may not) be the same as those for an ordinary bool, but being atomic is a larger concept with wider ramifications (e.g. restrictions on compiler re-ordering). Furthermore, some operations (like negation) are overloaded on the atomic operation to create a distinctly different instruction on the hardware than the native, non-atomic read-modify-write sequence of a non-atomic variable.

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