mirror of
https://gitlab.com/niansa/libcrosscoro.git
synced 2025-03-06 20:53:32 +01:00
82 lines
2.4 KiB
C++
82 lines
2.4 KiB
C++
#pragma once
|
|
|
|
#include <atomic>
|
|
#include <coroutine>
|
|
#include <mutex>
|
|
|
|
namespace coro
|
|
{
|
|
class semaphore
|
|
{
|
|
public:
|
|
explicit semaphore(std::ptrdiff_t least_max_value_and_starting_value);
|
|
explicit semaphore(std::ptrdiff_t least_max_value, std::ptrdiff_t starting_value);
|
|
~semaphore();
|
|
|
|
semaphore(const semaphore&) = delete;
|
|
semaphore(semaphore&&) = delete;
|
|
|
|
auto operator=(const semaphore&) noexcept -> semaphore& = delete;
|
|
auto operator=(semaphore&&) noexcept -> semaphore& = delete;
|
|
|
|
class acquire_operation
|
|
{
|
|
public:
|
|
explicit acquire_operation(semaphore& s);
|
|
|
|
auto await_ready() const noexcept -> bool;
|
|
auto await_suspend(std::coroutine_handle<> awaiting_coroutine) noexcept -> bool;
|
|
auto await_resume() const noexcept -> bool;
|
|
|
|
private:
|
|
friend semaphore;
|
|
|
|
semaphore& m_semaphore;
|
|
std::coroutine_handle<> m_awaiting_coroutine;
|
|
acquire_operation* m_next{nullptr};
|
|
};
|
|
|
|
auto release() -> void;
|
|
|
|
/**
|
|
* Acquires a resource from the semaphore, if the semaphore has no resources available then
|
|
* this will wait until a resource becomes available.
|
|
*/
|
|
[[nodiscard]] auto acquire() -> acquire_operation { return acquire_operation{*this}; }
|
|
|
|
/**
|
|
* Attemtps to acquire a resource if there is any resources available.
|
|
* @return True if the acquire operation was able to acquire a resource.
|
|
*/
|
|
auto try_acquire() -> bool;
|
|
|
|
/**
|
|
* @return The maximum number of resources the semaphore can contain.
|
|
*/
|
|
auto max() const noexcept -> std::ptrdiff_t { return m_least_max_value; }
|
|
|
|
/**
|
|
* The current number of resources available in this semaphore.
|
|
*/
|
|
auto value() const noexcept -> std::ptrdiff_t { return m_counter.load(std::memory_order::relaxed); }
|
|
|
|
/**
|
|
* Stops the semaphore and will notify all release/acquire waiters to wake up in a failed state.
|
|
* Once this is set it cannot be un-done and all future oprations on the semaphore will fail.
|
|
*/
|
|
auto stop_notify_all() noexcept -> void;
|
|
|
|
private:
|
|
friend class release_operation;
|
|
friend class acquire_operation;
|
|
|
|
const std::ptrdiff_t m_least_max_value;
|
|
std::atomic<std::ptrdiff_t> m_counter;
|
|
|
|
std::mutex m_waiter_mutex{};
|
|
acquire_operation* m_acquire_waiters{nullptr};
|
|
|
|
bool m_notify_all_set{false};
|
|
};
|
|
|
|
} // namespace coro
|