问题描述
在实现读写器锁时，我们可以使用 std :: shared_mutex 和 std :: shared_lock 和 std :: lock_guard 或 std :: unique_lock 。
In implementation of reader-writer lock, we can make use of the std::shared_mutex with std::shared_lock and std::lock_guard or std::unique_lock.
问题>是这个新功能的作家还是读者偏爱？
Question> Is this new feature writer or reader preferring?
根据安德鲁的评论进行更新
Update based on Andrew's comment
：
// Multiple threads/readers can read the counter's value at the same time.
unsigned int get() const {
std::shared_lock<std::shared_mutex> lock(mutex_);
return value_;
}
// Only one thread/writer can increment/write the counter's value.
void increment() {
std::unique_lock<std::shared_mutex> lock(mutex_);
value_++;
}
如上例所示，我无法控制阅读器/
As you can see from above example, I have no control on the reader/writer priority.
推荐答案
两者都不是（如果实施正确）。而是通过 fair 技术选择读者和作家作为下一个。这就是无法在API中设置此特征，也未指定该特征的原因。
It is neither (if implemented properly). Instead readers and writers are chosen to be next by a fair technique. And that is the reason that this characteristic is neither settable in the API, nor specified.
详细说明了如何实现。
This answer details how that is accomplished.
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