asyncpp::single_consumer_event Class Reference

Simple manual reset event supporting a single consumer. More...

#include <asyncpp/event.h>

Public Member Functions
constexpr	single_consumer_event (bool set_initially=false) noexcept
	Construct a new event.
bool	is_set () const noexcept
	Query if the event is currently set.
bool	is_awaited () const noexcept
	Query if the event is currently being awaited.
bool	set (dispatcher *resume_dispatcher=nullptr) noexcept
	Set the event.
void	reset () noexcept
	Reset the event back to unset.
auto	operator co_await () noexcept
	Suspend the current coroutine until the event is set.
constexpr auto	wait (dispatcher *resume_dispatcher=nullptr) noexcept
	Suspend the current coroutine until the event is set.

Detailed Description

Simple manual reset event supporting a single consumer.

This is similar in concept to a std::condition_variable and allows synchronization between coroutines, as well as normal code and coroutines. If the current coroutine co_await's the event it is suspended until some other coroutine or thread calls set(). If the event is already set when calling co_await the coroutine will directly continue execution in the current thread. If the event is not set, the coroutine gets resumed on the dispatcher that's passed into wait() or inside the call to set() if no dispatcher was provided. The operator co_await will behave as if wait() was called with the result of dispatcher::current(), meaning the coroutine is resumed on the same dispatcher it suspended (not necessarily the same thread, e.g. on a thread pool). If no dispatcher is associated with the current thread it is resumed inside set().

Note

single_consumer_event is threadsafe, however at most one coroutine can wait on it at any given time. Calling set(), reset() or is_set() from different threads at arbitrary times is fine, though it might be hard to predict the results.

Destroying a event thats currently being awaited can cause resource leaks as the waiting coroutine can never resume. (This asserts in debug mode)

Constructor & Destructor Documentation

single_consumer_event()

constexpr asyncpp::single_consumer_event::single_consumer_event ( bool set_initially = false )

inlineexplicitconstexprnoexcept

Construct a new event.

Parameters

set_initially

The initial state of the event (true => set, false => unset)

Member Function Documentation

is_awaited()

bool asyncpp::single_consumer_event::is_awaited ( ) const

inlinenoexcept

Query if the event is currently being awaited.

Note

Do not base decisions on this value, as it might change at any time by a call to set()

is_set()

bool asyncpp::single_consumer_event::is_set ( ) const

inlinenoexcept

Query if the event is currently set.

Note

Do not base decisions on this value, as it might change at any time by a call to reset()

operator co_await()

auto asyncpp::single_consumer_event::operator co_await ( )

inlinenoexcept

Suspend the current coroutine until the event is set.

If the event is already set, it resumes immediately on the current thread, otherwise the coroutine is suspended and waits until a call to set() is made. The coroutine will resume on the current dispatcher if the thread belongs to a dispatcher or inside set() if not.

Returns

Awaitable

set()

bool asyncpp::single_consumer_event::set ( dispatcher * resume_dispatcher = nullptr )

inlinenoexcept

Set the event.

Note

Depending on the way the event was awaited, the suspended coroutine might resume in this call.

Parameters

resume_dispatcher

Fallback dispatcher to use for resuming the coroutine if none was passed to wait()

Returns

true if a coroutine has been waiting and was resumed

wait()

constexpr auto asyncpp::single_consumer_event::wait ( dispatcher * resume_dispatcher = nullptr )

inlineconstexprnoexcept

Suspend the current coroutine until the event is set.

If the event is already set, it resumes immediately on the current thread, otherwise the coroutine is suspended and waits until a call to set() is made. The coroutine will resume on the provided dispatcher if not nullptr or inside set() if not.

Parameters

resume_dispatcher

The dispatcher to resume on or nullptr to resume inside set()

Returns

Awaitable

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The documentation for this class was generated from the following file:

• asyncpp/event.h