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Standard library header <semaphore> (C++20)

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C++
Standard library headers

此头文件是 线程支持 库的组成部分。

类

(C++20)
模拟非负资源计数的信号量
(类模板)
(C++20)
仅有两种状态的信号量
(类型别名)

概要 

namespace std {
  template<ptrdiff_t LeastMaxValue = /* implementation-defined */>
    class counting_semaphore;
  using binary_semaphore = counting_semaphore<1>;
}

类模板 std::counting_semaphore 

namespace std {
  template<ptrdiff_t LeastMaxValue = /* 由实现定义 */>
  class counting_semaphore {
  public:
    static constexpr ptrdiff_t max() noexcept;
    constexpr explicit counting_semaphore(ptrdiff_t desired);
    ~counting_semaphore();
    counting_semaphore(const counting_semaphore&) = delete;
    counting_semaphore& operator=(const counting_semaphore&) = delete;
    void release(ptrdiff_t update = 1);
    void acquire();
    bool try_acquire() noexcept;
    template<class Rep, class Period>
      bool try_acquire_for(const chrono::duration<Rep, Period>& rel_time);
    template<class Clock, class Duration>
      bool try_acquire_until(const chrono::time_point<Clock, Duration>& abs_time);
  private:
    ptrdiff_t counter;          // 仅用于说明
  };
}