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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/internal/event_notifier.h"

#include <libcamera/camera_manager.h>

#include "libcamera/internal/event_dispatcher.h"
#include "libcamera/internal/message.h"
#include "libcamera/internal/thread.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()