Class semaphore

examples/semaphore.cpp:10–22

#include <vector>

class semaphore {
   public:
    explicit semaphore(std::size_t limit) : chan_{limit} {}

    void acquire() { chan_ << empty_; }

    void release() { chan_ >> empty_; }

   private:
    struct empty {};
    msd::channel<empty> chan_;
    empty empty_{};  // See EBO starting C++20: https://en.cppreference.com/w/cpp/language/ebo.html
};

int simulate_heavy_computation(const int value)
{