带有std :: shared_lock的std :: shared_mutex是读者还是作家更喜欢？ [英] std::shared_mutex with std::shared_lock is reader or writer preferring?

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

参考：

  // 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.

此答案详细说明了如何实现。

This answer details how that is accomplished.

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