Vkm::Engine::Bus< EventT > Class Template Reference

Listener list plus deferred-event queue for a single event type. More...

#include <bus.h>

Inheritance diagram for Vkm::Engine::Bus< EventT >:

Public Member Functions
ListenerId	subscribe (std::function< void(const EventT &)> cb)
	Append a listener and return its new id.
bool	remove (ListenerId id)
	Erase the listener with id.
void	emit (const EventT &event)
	Dispatch event to every current listener synchronously.
void	enqueue (EventT event)
	Buffer event for delivery on the next flush().
void	takeQueue () override
	Swap the queue aside so what a listener enqueues cannot join it.
void	deliver () override
	Deliver the batch takeQueue set aside to every current listener.
bool	hasListeners () const override
	Whether any live listener remains, mid-dispatch removals aside.

Detailed Description

template<typename EventT>
class Vkm::Engine::Bus< EventT >

Listener list plus deferred-event queue for a single event type.

Driven only through EventBus.

Member Function Documentation

subscribe()

template<typename EventT>

ListenerId Vkm::Engine::Bus< EventT >::subscribe ( std::function< void(const EventT &)> cb )

inline

Append a listener and return its new id.

Mid-dispatch, the entry joins once the outermost dispatch unwinds: appending could reallocate the list and destroy the std::function whose operator() is on the stack.

Parameters

cb	Called with each event of this type delivered from now on.

Returns

The id remove() takes.

remove()

template<typename EventT>

bool Vkm::Engine::Bus< EventT >::remove ( ListenerId id )

inline

Erase the listener with id.

Callable from a listener, on itself too. Mid-dispatch the entry is only marked dead, reaped by admitPending: erasing would shift the index walk and skip a listener, and clearing the std::function would free the captures of the callback still running. An entry still in m_pending is erased outright, since nothing walks it.

Parameters

id	What subscribe() returned.

Returns

true if it was found - erased, or marked dead mid-dispatch.

emit()

template<typename EventT>

void Vkm::Engine::Bus< EventT >::emit ( const EventT & event )

inline

Dispatch event to every current listener synchronously.

Parameters

event

Passed to each listener.

enqueue()

template<typename EventT>

void Vkm::Engine::Bus< EventT >::enqueue ( EventT event )

inline

Buffer event for delivery on the next flush().

Parameters

event

Event to queue; moved in.

takeQueue()

template<typename EventT>

void Vkm::Engine::Bus< EventT >::takeQueue ( )

inlineoverridevirtual

Swap the queue aside so what a listener enqueues cannot join it.

Swaps with a retained member, so a steady frame allocates nothing.

Implements Vkm::Engine::IBus.

deliver()

template<typename EventT>

void Vkm::Engine::Bus< EventT >::deliver ( )

inlineoverridevirtual

Deliver the batch takeQueue set aside to every current listener.

An event a listener enqueues now fires on the next flush, whatever its type.

Implements Vkm::Engine::IBus.

hasListeners()

template<typename EventT>

bool Vkm::Engine::Bus< EventT >::hasListeners ( ) const

inlineoverridevirtual

Whether any live listener remains, mid-dispatch removals aside.

Returns

True while at least one live entry remains.

Implements Vkm::Engine::IBus.

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

• core/event/bus.h