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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* event_notifier.cpp - File descriptor event notifier
*/
#include <libcamera/base/event_notifier.h>
#include <libcamera/base/event_dispatcher.h>
#include <libcamera/base/message.h>
#include <libcamera/base/thread.h>
#include <libcamera/camera_manager.h>
/**
* \file event_notifier.h
* \brief File descriptor event notifier
*/
namespace libcamera {
/**
* \class EventNotifier
* \brief Notify of activity on a file descriptor
*
* The EventNotifier models a file descriptor event source that can be
* monitored. It is created with the file descriptor to be monitored and the
* type of event, and is enabled by default. It will emit the \ref activated
* signal whenever an event of the monitored type occurs on the file descriptor.
*
* Supported type of events are EventNotifier::Read, EventNotifier::Write and
* EventNotifier::Exception. The type is specified when constructing the
* notifier, and can be retrieved using the type() function. To listen to
* multiple event types on the same file descriptor multiple notifiers must be
* created.
*
* The notifier can be disabled with the setEnabled() function. When the notifier
* is disabled it ignores events and does not emit the \ref activated signal.
* The notifier can then be re-enabled with the setEnabled() function.
*
* Creating multiple notifiers of the same type for the same file descriptor is
* not allowed and results in undefined behaviour.
*
* Notifier events are detected and dispatched from the
* EventDispatcher::processEvents() function.
*/
/**
* \enum EventNotifier::Type
* Type of file descriptor event to listen for.
* \var EventNotifier::Read
* Data is available to be read from the file descriptor
* \var EventNotifier::Write
* Data can be written to the file descriptor
* \var EventNotifier::Exception
* An exception has occurred on the file descriptor
*/
/**
* \brief Construct an event notifier with a file descriptor and event type
* \param[in] fd The file descriptor to monitor
* \param[in] type The event type to monitor
* \param[in] parent The parent Object
*/
EventNotifier::EventNotifier(int fd, Type type, Object *parent)
: Object(parent), fd_(fd), type_(type), enabled_(false)
{
setEnabled(true);
}
EventNotifier::~EventNotifier()
{
setEnabled(false);
}
/**
* \fn EventNotifier::type()
* \brief Retrieve the type of the event being monitored
* \return The type of the event
*/
/**
* \fn EventNotifier::fd()
* \brief Retrieve the file descriptor being monitored
* \return The file descriptor
*/
/**
* \fn EventNotifier::enabled()
* \brief Retrieve the notifier state
* \return True if the notifier is enabled, or false otherwise
* \sa setEnabled()
*/
/**
* \brief Enable or disable the notifier
* \param[in] enable True to enable the notifier, false to disable it
*
* This function enables or disables the notifier. A disabled notifier ignores
* events and does not emit the \ref activated signal.
*
* \context This function is \threadbound.
*/
void EventNotifier::setEnabled(bool enable)
{
if (enabled_ == enable)
return;
enabled_ = enable;
EventDispatcher *dispatcher = thread()->eventDispatcher();
if (enable)
dispatcher->registerEventNotifier(this);
else
dispatcher->unregisterEventNotifier(this);
}
/**
* \var EventNotifier::activated
* \brief Signal emitted when the event occurs
*
* This signal is emitted when the event \ref type() occurs on the file
* descriptor monitored by the notifier. The notifier pointer is passed as a
* parameter.
*/
void EventNotifier::message(Message *msg)
{
if (msg->type() == Message::ThreadMoveMessage) {
if (enabled_) {
setEnabled(false);
invokeMethod(&EventNotifier::setEnabled,
ConnectionTypeQueued, true);
}
}
Object::message(msg);
}
} /* namespace libcamera */
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