libcamera: Document thread-safety attributes of core classes

Define the thread-safety attributes of the classes and methods that are
either thread-safe or thread-bound. The CameraManager, Camera and
PipelineHandler will be addressed separately.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/device_enumerator.cpp

@@ -190,6 +190,8 @@ DeviceEnumerator::~DeviceEnumerator()
  * with a warning message logged, without returning an error. Only errors that
  * prevent enumeration altogether shall be fatal.
  *
+ * \context This function is \threadbound.
+ *
  * \return 0 on success or a negative error code otherwise
  */
 

src/libcamera/event_notifier.cpp

@@ -99,6 +99,8 @@ EventNotifier::~EventNotifier()
  *
  * 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)
 {

src/libcamera/ipc_unixsocket.cpp

@@ -62,6 +62,8 @@ LOG_DEFINE_CATEGORY(IPCUnixSocket)
  * communication method. The remote side then instantiates a socket, and binds
  * it to the other side by passing the file descriptor to bind(). At that point
  * the channel is operation and communication is bidirectional and symmmetrical.
+ *
+ * \context This class is \threadbound.
  */
 
 IPCUnixSocket::IPCUnixSocket()

src/libcamera/object.cpp

@@ -110,6 +110,8 @@ Object::~Object()
  * Messages are delivered through the thread's event loop. If the thread is not
  * running its event loop the message will not be delivered until the event
  * loop gets started.
+ *
+ * \context This function is \threadsafe.
  */
 void Object::postMessage(std::unique_ptr<Message> msg)
 {
@@ -162,6 +164,8 @@ void Object::message(Message *msg)
  * are passed untouched. The caller shall ensure that any pointer argument
  * remains valid until the method is invoked.
  *
+ * \context This function is \threadsafe.
+ *
  * \return For connection types ConnectionTypeDirect and
  * ConnectionTypeBlocking, return the return value of the invoked method. For
  * connection type ConnectionTypeQueued, return a default-constructed R value.
@@ -170,6 +174,7 @@ void Object::message(Message *msg)
 /**
  * \fn Object::thread()
  * \brief Retrieve the thread the object is bound to
+ * \context This function is \threadsafe.
  * \return The thread the object is bound to
  */
 
@@ -178,8 +183,7 @@ void Object::message(Message *msg)
  * \param[in] thread The target thread
  *
  * This method moves the object and all its children from the current thread to
- * the new \a thread. It shall be called from the thread in which the object
- * currently lives, otherwise the behaviour is undefined.
+ * the new \a thread.
  *
  * Before the object is moved, a Message::ThreadMoveMessage message is sent to
  * it. The message() method can be reimplement in derived classes to be notified
@@ -187,6 +191,8 @@ void Object::message(Message *msg)
  *
  * Moving an object that has a parent is not allowed, and causes undefined
  * behaviour.
+ *
+ * \context This function is thread-bound.
  */
 void Object::moveToThread(Thread *thread)
 {

src/libcamera/thread.cpp

@@ -222,6 +222,8 @@ ThreadData *ThreadData::current()
  * called. A custom event dispatcher may be installed with
  * setEventDispatcher(), otherwise a poll-based event dispatcher is used. This
  * behaviour can be overriden by overloading the run() method.
+ *
+ * \context This class is \threadsafe.
  */
 
 /**

src/libcamera/timer.cpp

@@ -67,16 +67,18 @@ Timer::~Timer()
  * \brief Start or restart the timer with a timeout of \a msec
  * \param[in] msec The timer duration in milliseconds
  *
- * This method shall be called from the thread the timer is associated with. If
- * the timer is already running it will be stopped and restarted.
+ * If the timer is already running it will be stopped and restarted.
+ *
+ * \context This function is \threadbound.
  */
 
 /**
  * \brief Start or restart the timer with a timeout of \a duration
  * \param[in] duration The timer duration in milliseconds
  *
- * This method shall be called from the thread the timer is associated with. If
- * the timer is already running it will be stopped and restarted.
+ * If the timer is already running it will be stopped and restarted.
+ *
+ * \context This function is \threadbound.
  */
 void Timer::start(std::chrono::milliseconds duration)
 {
@@ -87,8 +89,9 @@ void Timer::start(std::chrono::milliseconds duration)
  * \brief Start or restart the timer with a \a deadline
  * \param[in] deadline The timer deadline
  *
- * This method shall be called from the thread the timer is associated with. If
- * the timer is already running it will be stopped and restarted.
+ * If the timer is already running it will be stopped and restarted.
+ *
+ * \context This function is \threadbound.
  */
 void Timer::start(std::chrono::steady_clock::time_point deadline)
 {
@@ -115,8 +118,9 @@ void Timer::start(std::chrono::steady_clock::time_point deadline)
  * After this function returns the timer is guaranteed not to emit the
  * \ref timeout signal.
  *
- * This method shall be called from the thread the timer is associated with. If
- * the timer is not running this function performs no operation.
+ * If the timer is not running this function performs no operation.
+ *
+ * \context This function is \threadbound.
  */
 void Timer::stop()
 {

src/libcamera/v4l2_videodevice.cpp

@@ -403,6 +403,8 @@ const std::string V4L2DeviceFormat::toString() const
  *
  * Upon destruction any device left open will be closed, and any resources
  * released.
+ *
+ * \context This class is \threadbound.
  */
 
 /**