libcamera::EventNotifier Class Reference

Notify of activity on a file descriptor. More...

Inheritance diagram for libcamera::EventNotifier:

Collaboration diagram for libcamera::EventNotifier:

Public Types
enum	Type { Read, Write, Exception }

Public Member Functions
	EventNotifier (int fd, Type type, Object *parent=nullptr)
	Construct an event notifier with a file descriptor and event type. More...
Type	type () const
	Retrieve the type of the event being monitored. More...
int	fd () const
	Retrieve the file descriptor being monitored. More...
bool	enabled () const
	Retrieve the notifier state. More...
void	setEnabled (bool enable)
	Enable or disable the notifier. More...
Public Member Functions inherited from libcamera::Object
	Object (Object *parent=nullptr)
	Construct an Object instance. More...
virtual	~Object ()
	Destroy an Object instance. More...
void	deleteLater ()
	Schedule deletion of the instance in the thread it belongs to. More...
void	postMessage (std::unique_ptr< Message > msg)
	Post a message to the object's thread. More...
template<typename T , typename R , typename... FuncArgs, typename... Args, std::enable_if_t< std::is_base_of< Object, T >::value > * = nullptr>
R	invokeMethod (R(T::*func)(FuncArgs...), ConnectionType type, Args &&... args)
	Invoke a method asynchronously on an Object instance. More...
Thread *	thread () const
	Retrieve the thread the object is bound to. More...
void	moveToThread (Thread *thread)
	Move the object and all its children to a different thread. More...
Object *	parent () const
	Retrieve the object's parent. More...

Public Attributes
Signal	activated
	Signal emitted when the event occurs. More...

Protected Member Functions
void	message (Message *msg) override
	Message handler for the object. More...
Protected Member Functions inherited from libcamera::Object
bool	assertThreadBound (const char *message)
	Check if the caller complies with thread-bound constraints. More...

Detailed Description

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 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 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.

Member Enumeration Documentation

Type

enum libcamera::EventNotifier::Type

Type of file descriptor event to listen for.

Enumerator
Read	Data is available to be read from the file descriptor
Write	Data can be written to the file descriptor
Exception	An exception has occurred on the file descriptor

Constructor & Destructor Documentation

EventNotifier()

libcamera::EventNotifier::EventNotifier	(	int	fd,
		Type	type,
		Object *	parent = nullptr
	)

Construct an event notifier with a file descriptor and event type.

Parameters

[in]	fd	The file descriptor to monitor
[in]	type	The event type to monitor
[in]	parent	The parent Object

Member Function Documentation

enabled()

libcamera::EventNotifier::enabled ( ) const

inline

Retrieve the notifier state.

Returns

True if the notifier is enabled, or false otherwise

See also

setEnabled()

fd()

libcamera::EventNotifier::fd ( ) const

inline

Retrieve the file descriptor being monitored.

Returns

The file descriptor

message()

void libcamera::EventNotifier::message ( Message *  msg )

overrideprotectedvirtual

Message handler for the object.

Parameters

[in]

msg

The message

This virtual function receives messages for the object. It is called in the context of the object's thread, and can be overridden to process custom messages. The parent Object::message() function shall be called for any message not handled by the override function.

The message msg is valid only for the duration of the call, no reference to it shall be kept after this function returns.

Reimplemented from libcamera::Object.

setEnabled()

void libcamera::EventNotifier::setEnabled

(

bool

enable

)

Enable or disable the notifier.

Parameters

[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 activated signal.

Thread Safety:

This function is thread-bound.

type()

libcamera::EventNotifier::type ( ) const

inline

Retrieve the type of the event being monitored.

Returns

The type of the event

Member Data Documentation

activated

libcamera::EventNotifier::activated

Signal emitted when the event occurs.

This signal is emitted when the event type() occurs on the file descriptor monitored by the notifier. The notifier pointer is passed as a parameter.

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The documentation for this class was generated from the following files:

• include/libcamera/base/event_notifier.h
• src/libcamera/base/event_notifier.cpp