#include <async/oneshot-event.hpp>

oneshot_event is an event type that can be only raised once, and supports multiple waiters. After the initial raise, any further waits will complete immediately, and further raises will be a no-op.


struct oneshot_event {
	void raise(); // (1)

	sender wait(cancellation_token ct); // (2)
	sender wait(); // (3)
  1. Raises an event.
  2. Returns a sender for the wait operation. The operation waits for the event to be raised.
  3. Same as (2) but it cannot be cancelled.


  • ct - the cancellation token to use to listen for cancellation.

Return values

  1. This method doesn't return any value.
  2. This method returns a sender of unspecified type. The sender completes with either true to indicate success, or false to indicate that the wait was cancelled.
  3. Same as (2) except the sender completes without a value.


async::oneshot_event ev;

auto coro = [] (async::oneshot_event &ev) -> async::detached {
	std::cout << "Before wait" << std::endl;
	co_await ev.wait();
	std::cout << "After wait" << std::endl;

std::cout << "Before raise" << std::endl;
std::cout << "After raise" << std::endl;


Before wait
Before raise
After wait
After raise
Before wait
After wait