event_bus Class Reference

A typed, thread-safe, in-process publish/subscribe event bus. More...

#include <event_bus.hpp>

Collaboration diagram for event_bus:

Public Member Functions
	event_bus (const event_bus &)=delete
event_bus &	operator= (const event_bus &)=delete
	event_bus (event_bus &&)=delete
event_bus &	operator= (event_bus &&)=delete
template<typename Event >
subscription	subscribe (std::function< void(const Event &)> handler)
	Subscribe to events of a specific type.
template<typename Event >
void	publish (const Event &event)
	Publish an event to all subscribers.
template<typename Event >
std::size_t	subscriber_count () const
	Get the number of subscribers for a specific event type.

Detailed Description

A typed, thread-safe, in-process publish/subscribe event bus.

The event bus provides a decoupled communication mechanism between components. Publishers emit events without knowing who subscribes, and subscribers receive events without knowing who publishes them.

Thread Safety:

• All operations (publish, subscribe, unsubscribe) are thread-safe.
• Callbacks are invoked synchronously during publish(), so they should be non-blocking to avoid holding the lock for extended periods.

Usage:

event_bus bus;
 
// Subscribe to an event type
auto sub = bus.subscribe<my_event>([](const my_event& e) {
    // Handle event
});
 
// Publish an event
bus.publish(my_event{...});
 
// Subscription automatically cleaned up when 'sub' goes out of scope

Member Function Documentation

subscribe()

template<typename Event >

subscription subscribe

(

std::function< void(const Event &)>

handler

)

Subscribe to events of a specific type.

Template Parameters

Event

The event type to subscribe to.

Parameters

handler

The callback function to invoke when an event is published.

Returns

A subscription handle that unsubscribes when destroyed.

Note

The handler is invoked synchronously during publish(). It should be non-blocking to avoid holding the bus lock for extended periods.

publish()

template<typename Event >

void publish

(

const Event &

event

)

Publish an event to all subscribers.

Template Parameters

Event

The event type being published.

Parameters

event

The event instance to publish.

All registered handlers for this event type will be invoked synchronously. Exceptions thrown by handlers are caught and logged, but do not prevent other handlers from being called.

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subscriber_count()

template<typename Event >

std::size_t subscriber_count

(

)

const

Get the number of subscribers for a specific event type.

Template Parameters

Event

The event type to query.

Returns

The number of active subscriptions for this event type.