{

public:

when_all_counter(std::size_t count) noexcept

: m_count(count + 1)

, m_awaitingCoroutine(nullptr)

{}

bool is_ready() const noexcept

{

// We consider this complete if we're asking whether it's ready

// after a coroutine has already been registered.

return static_cast<bool>(m_awaitingCoroutine);

}

bool try_await(cppcoro::coroutine_handle<> awaitingCoroutine) noexcept

{

m_awaitingCoroutine = awaitingCoroutine;

return m_count.fetch_sub(1, std::memory_order_acq_rel) > 1;

}

void notify_awaitable_completed() noexcept

{

if (m_count.fetch_sub(1, std::memory_order_acq_rel) == 1)

{

m_awaitingCoroutine.resume();

}

}

protected:

std::atomic<std::size_t> m_count;

cppcoro::coroutine_handle<> m_awaitingCoroutine;