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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* event_dispatcher.cpp - Event dispatcher
*/
#include "libcamera/internal/event_dispatcher.h"
#include "libcamera/internal/log.h"
/**
* \file event_dispatcher.h
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(Event)
/**
* \class EventDispatcher
* \brief Interface to manage the libcamera events and timers
*
* The EventDispatcher class allows the integration of the application event
* loop with libcamera by abstracting how events and timers are managed and
* processed.
*
* To listen to events, libcamera creates EventNotifier instances and registers
* them with the dispatcher with registerEventNotifier(). The event notifier
* \ref EventNotifier::activated signal is then emitted by the dispatcher
* whenever the event is detected.
*
* To set timers, libcamera creates Timer instances and registers them with the
* dispatcher with registerTimer(). The timer \ref Timer::timeout signal is then
* emitted by the dispatcher when the timer times out.
*/
EventDispatcher::~EventDispatcher()
{
}
/**
* \fn EventDispatcher::registerEventNotifier()
* \brief Register an event notifier
* \param[in] notifier The event notifier to register
*
* Once the \a notifier is registered with the dispatcher, the dispatcher will
* emit the notifier \ref EventNotifier::activated signal whenever a
* corresponding event is detected on the notifier's file descriptor. The event
* is monitored until the notifier is unregistered with
* unregisterEventNotifier().
*
* Registering multiple notifiers for the same file descriptor and event type is
* not allowed and results in undefined behaviour.
*/
/**
* \fn EventDispatcher::unregisterEventNotifier()
* \brief Unregister an event notifier
* \param[in] notifier The event notifier to unregister
*
* After this function returns the \a notifier is guaranteed not to emit the
* \ref EventNotifier::activated signal.
*
* If the notifier isn't registered, this function performs no operation.
*/
/**
* \fn EventDispatcher::registerTimer()
* \brief Register a timer
* \param[in] timer The timer to register
*
* Once the \a timer is registered with the dispatcher, the dispatcher will emit
* the timer \ref Timer::timeout signal when the timer times out. The timer can
* be unregistered with unregisterTimer() before it times out, in which case the
* signal will not be emitted.
*
* When the \a timer times out, it is automatically unregistered by the
* dispatcher and can be registered back as early as from the \ref Timer::timeout
* signal handlers.
*
* Registering the same timer multiple times is not allowed and results in
* undefined behaviour.
*/
/**
* \fn EventDispatcher::unregisterTimer()
* \brief Unregister a timer
* \param[in] timer The timer to unregister
*
* After this function returns the \a timer is guaranteed not to emit the
* \ref Timer::timeout signal.
*
* If the timer isn't registered, this function performs no operation.
*/
/**
* \fn EventDispatcher::processEvents()
* \brief Wait for and process pending events
*
* This function processes all pending events associated with registered event
* notifiers and timers and signals the corresponding EventNotifier and Timer
* objects. If no events are pending, it waits for the first event and processes
* it before returning.
*/
/**
* \fn EventDispatcher::interrupt()
* \brief Interrupt any running processEvents() call as soon as possible
*
* Calling this function interrupts any blocking processEvents() call in
* progress. The processEvents() function will return as soon as possible,
* after processing pending timers and events. If processEvents() isn't in
* progress, it will be interrupted immediately the next time it gets called.
*/
} /* namespace libcamera */
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