4d470eb37f
The new interrupt() function allows interrupting in-progress blocking processEvents() calls. This is useful to stop running event loops. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
118 lines
3.7 KiB
C++
118 lines
3.7 KiB
C++
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/*
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* Copyright (C) 2019, Google Inc.
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*
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* event_dispatcher.cpp - Event dispatcher
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*/
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#include <libcamera/event_dispatcher.h>
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#include "log.h"
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/**
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* \file event_dispatcher.h
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*/
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namespace libcamera {
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LOG_DEFINE_CATEGORY(Event)
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/**
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* \class EventDispatcher
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* \brief Interface to manage the libcamera events and timers
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*
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* The EventDispatcher class allows the integration of the application event
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* loop with libcamera by abstracting how events and timers are managed and
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* processed.
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*
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* To listen to events, libcamera creates EventNotifier instances and registers
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* them with the dispatcher with registerEventNotifier(). The event notifier
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* \ref EventNotifier::activated signal is then emitted by the dispatcher
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* whenever the event is detected.
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*
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* To set timers, libcamera creates Timer instances and registers them with the
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* dispatcher with registerTimer(). The timer \ref Timer::timeout signal is then
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* emitted by the dispatcher when the timer times out.
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*/
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EventDispatcher::~EventDispatcher()
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{
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}
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/**
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* \fn EventDispatcher::registerEventNotifier()
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* \brief Register an event notifier
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* \param notifier The event notifier to register
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*
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* Once the \a notifier is registered with the dispatcher, the dispatcher will
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* emit the notifier \ref EventNotifier::activated signal whenever a
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* corresponding event is detected on the notifier's file descriptor. The event
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* is monitored until the notifier is unregistered with
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* unregisterEventNotifier().
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*
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* Registering multiple notifiers for the same file descriptor and event type is
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* not allowed and results in undefined behaviour.
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*/
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/**
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* \fn EventDispatcher::unregisterEventNotifier()
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* \brief Unregister an event notifier
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* \param notifier The event notifier to unregister
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*
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* After this function returns the \a notifier is guaranteed not to emit the
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* \ref EventNotifier::activated signal.
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*
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* If the notifier isn't registered, this function performs no operation.
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*/
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/**
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* \fn EventDispatcher::registerTimer()
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* \brief Register a timer
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* \param timer The timer to register
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*
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* Once the \a timer is registered with the dispatcher, the dispatcher will emit
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* the timer \ref Timer::timeout signal when the timer times out. The timer can
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* be unregistered with unregisterTimer() before it times out, in which case the
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* signal will not be emitted.
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*
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* When the \a timer times out, it is automatically unregistered by the
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* dispatcher and can be registered back as early as from the \ref Timer::timeout
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* signal handlers.
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*
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* Registering the same timer multiple times is not allowed and results in
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* undefined behaviour.
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*/
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/**
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* \fn EventDispatcher::unregisterTimer()
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* \brief Unregister a timer
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* \param timer The timer to unregister
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*
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* After this function returns the \a timer is guaranteed not to emit the
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* \ref Timer::timeout signal.
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*
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* If the timer isn't registered, this function performs no operation.
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*/
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/**
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* \fn EventDispatcher::processEvents()
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* \brief Wait for and process pending events
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*
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* This function processes all pending events associated with registered event
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* notifiers and timers and signals the corresponding EventNotifier and Timer
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* objects. If no events are pending, it waits for the first event and processes
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* it before returning.
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*/
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/**
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* \fn EventDispatcher::interrupt()
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* \brief Interrupt any running processEvents() call as soon as possible
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*
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* Calling this function interrupts any blocking processEvents() call in
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* progress. The processEvents() function will return as soon as possible,
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* after processing pending timers and events. If processEvents() isn't in
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* progress, it will be interrupted immediately the next time it gets called.
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*/
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} /* namespace libcamera */
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