nrEngine::EventChannel Class Reference
[Event-Management]

Event channel used for communication between application/engine's components. More...

Public Member Functions
	EventChannel (EventManager *manager, const std::string &name)
	Create a new instance of the communication channel.
virtual	~EventChannel ()
	Releas eused memory and destroy hte instance.
Result	add (EventActor *actor, bool notice=true)
Result	del (EventActor *actor, bool notice=true)
NR_FORCEINLINE const std::string &	getName () const
void	emit (SharedPtr< Event > event)
void	push (SharedPtr< Event > event)
void	deliver ()
Protected Types
typedef std::map< std::string, EventActor * >	ActorDatabase
	Store here the mapping between actor names and their connections.
typedef std::priority_queue< SharedPtr< Event >, std::vector< SharedPtr< Event > >, GreatEvent< SharedPtr< Event > > >	EventQueue
	We store our event messages in a priority queue.
Protected Member Functions
bool	isConnected (const std::string &name)
	Check whenever a given actor is already connected.
void	_disconnectAll ()
	Disconnect all actors from the channel.
Protected Attributes
std::string	mName
	Unique name of the communication channel.
EventManager *	mParentManager
	We always does store a pointer to the event manager where this channel belongs to.
ActorDatabase	mActorDb
	Connected actor database.
EventQueue	mEventQueue
	Store the event messages in this variable.
Friends
class	EventManager
	The event manager system is a friend to this class.
Data Structures
struct	GreatEvent

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Detailed Description

Event channel used for communication between application/engine's components.

EventChannel represents a message bus for the communication between system components. Events/messages could be send through this channel to all listeners connected to this channel.

In our engine we mix the concept of event messaging and state machines. So we do not have only events but also states. The states are stored in communication channels, so each listener of a channel could also be noticed if any state changes. This is also how we handle it in the nrEngine.

The communication actors are connected to the channel by its name. Also the lifetime of each actor is tracked. So if an actor is removed from the memory, so it will be automaticaly disconnected from the database. We do not use smart pointers for this purpose, because it will cause in undefined working flow. i.e. if you think the actor is removed from the memory because you have deleted it, it still get noticed about the things going on the channel. So this will ends up in undefined state.In our implementation the destructor of EventActor does simply say all channels it connected to, that the object does not exists anymore, so it can be disconnected.

Definition at line 52 of file EventChannel.h.

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Member Function Documentation

Result nrEngine::EventChannel::add	(	EventActor *	actor,
		bool	notice = true
	)

Connect a new actor to the channel. The actor will be connected so it get noticed about any communication on the channel.

The actor has to implement default event reactions needed for our channel communication system. Compilation error will occur if the reactions to the default events are not implemented.

Parameters:

	actor	An actor to connect to the channel
	notice	Should channel let notice the actor that he is connected now (default YES)

Definition at line 34 of file EventChannel.cpp.

References nrEngine::EventActor::_noticeConnected(), nrEngine::EVENT_ALREADY_CONNECTED, nrEngine::EVENT_NO_VALID_ACTOR, getName(), nrEngine::EventActor::getName(), isConnected(), nrEngine::Log::LL_DEBUG, nrEngine::Log::LL_ERROR, nrEngine::Log::LOG_ENGINE, mActorDb, and nrEngine::OK.

Result nrEngine::EventChannel::del	(	EventActor *	actor,
		bool	notice = true
	)

Disconnect an actor from the channel. It is a good coding style if you call this function, when you do not need the connection anymore. However our engine does provide you the possibility to forget about disconnecting the actors from the channel, because the lifetime of an actor will be tracked. If the object does not exists anymore, so it will be automaticaly disconnected.

If you want to be performant, so remove actors from the channels, if they do not need the connection anymore.

Parameters:

	actor	An actor already connected to the channel
	notice	Should channel notice the actor, about disconnection (default YES)

Definition at line 60 of file EventChannel.cpp.

References nrEngine::EventActor::_noticeDisconnected(), nrEngine::EVENT_NOT_CONNECTED, getName(), nrEngine::EventActor::getName(), isConnected(), nrEngine::Log::LL_DEBUG, nrEngine::Log::LOG_ENGINE, mActorDb, and nrEngine::OK.

NR_FORCEINLINE const std::string& nrEngine::EventChannel::getName

(

)

const

Get the name of the channel

Definition at line 93 of file EventChannel.h.

Referenced by _disconnectAll(), nrEngine::EventActor::_noticeConnected(), nrEngine::EventActor::_noticeDisconnected(), add(), and del().

void nrEngine::EventChannel::emit

(

SharedPtr< Event >

event

)

Emit a certain event to a channel. This will send this event to all connected actors, so they get noticed about new event.

Parameters:

event

Smart pointer to an event object

Definition at line 105 of file EventChannel.cpp.

References mActorDb.

Referenced by deliver(), and push().

void nrEngine::EventChannel::push

(

SharedPtr< Event >

event

)

Instead of emit() this will not send the message directly to the channel listeners, but it store the message first in a queue based on priority numbers of the events. When you call deliver(), then all messages are getting delivered to the channel listeners

Parameters:

event

Smart pointer to the event message

NOTE: If event priority is immediately so the message will be emitted immediately without be stored in the queue

Definition at line 115 of file EventChannel.cpp.

References emit(), nrEngine::CPriority::IMMEDIATE, and mEventQueue.

void nrEngine::EventChannel::deliver

(

)

Deliver all stored event messages from the queue to the actors connected to the channel.

Definition at line 127 of file EventChannel.cpp.

References emit(), and mEventQueue.

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

• EventChannel.h
• EventChannel.cpp

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