std::condition_variable 和 std::condition_variable_any 有什么区别? [英] What is the difference between std::condition_variable and std::condition_variable_any?

问题描述

我可能遗漏了一些明显的东西，但我看不出 std::condition_variable 和 std::condition_variable_any 之间有什么区别.为什么我们需要两者?

I'm probably missing something obvious, but I can't see any difference between std::condition_variable and std::condition_variable_any. Why do we need both?

推荐答案

std::condition_variable 更专业，因此在不需要 的灵活性时可以更高效std::condition_variable_any.

std::condition_variable is more specialized, and therefore can be more efficient when you don't need the flexibility of std::condition_variable_any.

来自 N3290 §30.5[thread.condition]/1

From N3290 §30.5[thread.condition]/1

类 condition_variable 提供一个只能等待 unique_lock 类型的对象的条件变量，允许最大在某些平台上的效率.condition_variable_any 类提供了一个通用条件变量可以等待用户提供的锁类型的对象.

Class condition_variable provides a condition variable that can only wait on an object of type unique_lock<mutex>, allowing maximum efficiency on some platforms. Class condition_variable_any provides a general condition variable that can wait on objects of user-supplied lock types.

实际上，在 LLVM 的 libc++ 中，condition_variable_any 是在 shared_mutex 上使用更专业的 condition_variable(使用 pthread_cond_t)实现的.

Actually, in LLVM's libc++, condition_variable_any is implemented using the more specialized condition_variable (which uses pthread_cond_t) on a shared_mutex.

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