EventLoop Class Referenceabstract

#include <Pt/System/EventLoop.h>

Thread-safe event loop supporting I/O multiplexing and Timers. More...

Inherits Connectable, and EventSink.

Inherited by MainLoop.

Public Member Functions

virtual ~EventLoop ()
void commitEvent (const Event &ev)
 Queues an event and triggers event processing.
Signal< const Event & > & eventReceived ()
 Reports all events.
void exit ()
 Stops the loop.
Signalexited ()
 Emited when the eventloop is exited.
void post (Selectable &s)
 Calls the selectables run function in the loop thread. More...
void processEvents ()
 Process all queued events.
void queueEvent (const Event &ev)
 Only queues an event.
void run ()
 Starts the loop.
void wake ()
 Triggers event processing.

Protected Member Functions

virtual void onCommitEvent (const Event &ev)=0
 Queues an event and triggers event processing.
virtual void onQueueEvent (const Event &ev)=0
 Only queues an event.
virtual void onWake ()=0
 Triggers event processing.

Detailed Description

The EventLoop can be used as the central entity of a thread or process to dispatch application events and wait on multiple Selectables, IODevices or Timers for activity.

Events can be added to the internal event queue, even from other threads using the method commitEvent() or queueEvent(). The first method will add the event to the internal queue and wake the event loop, the latter allows queing multiple events and it is up to the caller to wake the event loop by calling wake() when all events are added. When the event loop processes its event, the signal eventReceived is send for each processed event. Events are processed in the order they were added.

To start the MainLoop the method run() must be executed. It blocks until the event loop is stopped. To stop the loop, exit() can be called. The delivery of the events occurs inside the thread that started the execution of the event loop.

Member Function Documentation

void post ( Selectable s)

The event loop is woken up and the selectable's run function is called in the thread that called the event loop's run function. This function may be called from any thread, since it is meant to return to the event loop thread from a selectable, that is based on a parallel execution model e.g. using a worker thread.