libcamera: Drop emitter object pointer from signal arguments

Many signals used in internal and public APIs carry the emitter pointer
as a signal argument. This was done to allow slots connected to multiple
signal instances to differentiate between emitters. While starting from
a good intention of facilitating the implementation of slots, it turned
out to be a bad API design as the signal isn't meant to know what it
will be connected to, and thus shouldn't carry parameters that are
solely meant to support a use case specific to the connected slot.

These pointers turn out to be unused in all slots but one. In the only
case where it is needed, it can be obtained by wrapping the slot in a
lambda function when connecting the signal. Do so, and drop the emitter
pointer from all signals.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

src/libcamera/base/event_dispatcher_poll.cpp

@@ -278,7 +278,7 @@ void EventDispatcherPoll::processNotifiers(const std::vector<struct pollfd> &pol
 			}
 
 			if (pfd.revents & event.events)
-				notifier->activated.emit(notifier);
+				notifier->activated.emit();
 		}
 
 		/* Erase the notifiers_ entry if it is now empty. */
@@ -300,7 +300,7 @@ void EventDispatcherPoll::processTimers()
 
 		timers_.pop_front();
 		timer->stop();
-		timer->timeout.emit(timer);
+		timer->timeout.emit();
 	}
 }
 

src/libcamera/base/thread.cpp

@@ -384,7 +384,7 @@ void Thread::finishThread()
 	data_->running_ = false;
 	data_->mutex_.unlock();
 
-	finished.emit(this);
+	finished.emit();
 	data_->cv_.notify_all();
 }
 

src/libcamera/camera.cpp

@@ -688,7 +688,7 @@ void Camera::disconnect()
 	LOG(Camera, Debug) << "Disconnecting camera " << id();
 
 	_d()->disconnect();
-	disconnected.emit(this);
+	disconnected.emit();
 }
 
 int Camera::exportFrameBuffers(Stream *stream,

src/libcamera/device_enumerator.cpp

@@ -288,7 +288,7 @@ void DeviceEnumerator::removeDevice(const std::string &deviceNode)
 	LOG(DeviceEnumerator, Debug)
 		<< "Media device for node " << deviceNode << " removed.";
 
-	media->disconnected.emit(media.get());
+	media->disconnected.emit();
 }
 
 /**

src/libcamera/device_enumerator_udev.cpp

@@ -327,7 +327,7 @@ int DeviceEnumeratorUdev::addV4L2Device(dev_t devnum)
 	return 0;
 }
 
-void DeviceEnumeratorUdev::udevNotify([[maybe_unused]] EventNotifier *notifier)
+void DeviceEnumeratorUdev::udevNotify()
 {
 	struct udev_device *dev = udev_monitor_receive_device(monitor_);
 	std::string action(udev_device_get_action(dev));

src/libcamera/ipc_pipe_unixsocket.cpp

@@ -82,7 +82,7 @@ int IPCPipeUnixSocket::sendAsync(const IPCMessage &data)
 	return 0;
 }
 
-void IPCPipeUnixSocket::readyRead([[maybe_unused]] IPCUnixSocket *socket)
+void IPCPipeUnixSocket::readyRead()
 {
 	IPCUnixSocket::Payload payload;
 	int ret = socket_->receive(&payload);

src/libcamera/ipc_unixsocket.cpp

@@ -311,7 +311,7 @@ int IPCUnixSocket::recvData(void *buffer, size_t length,
 	return 0;
 }
 
-void IPCUnixSocket::dataNotifier([[maybe_unused]] EventNotifier *notifier)
+void IPCUnixSocket::dataNotifier()
 {
 	int ret;
 
@@ -342,7 +342,7 @@ void IPCUnixSocket::dataNotifier([[maybe_unused]] EventNotifier *notifier)
 		return;
 
 	notifier_->setEnabled(false);
-	readyRead.emit(this);
+	readyRead.emit();
 }
 
 } /* namespace libcamera */

src/libcamera/pipeline_handler.cpp

@@ -448,7 +448,7 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
  */
 void PipelineHandler::hotplugMediaDevice(MediaDevice *media)
 {
-	media->disconnected.connect(this, &PipelineHandler::mediaDeviceDisconnected);
+	media->disconnected.connect(this, [=]() { mediaDeviceDisconnected(media); });
 }
 
 /**

src/libcamera/process.cpp

@@ -66,7 +66,7 @@ void sigact(int signal, siginfo_t *info, void *ucontext)
 
 } /* namespace */
 
-void ProcessManager::sighandler([[maybe_unused]] EventNotifier *notifier)
+void ProcessManager::sighandler()
 {
 	char data;
 	ssize_t ret = read(pipe_[0], &data, sizeof(data));
@@ -326,7 +326,7 @@ void Process::died(int wstatus)
 	exitStatus_ = WIFEXITED(wstatus) ? NormalExit : SignalExit;
 	exitCode_ = exitStatus_ == NormalExit ? WEXITSTATUS(wstatus) : -1;
 
-	finished.emit(this, exitStatus_, exitCode_);
+	finished.emit(exitStatus_, exitCode_);
 }
 
 /**

src/libcamera/v4l2_device.cpp

@@ -705,12 +705,11 @@ void V4L2Device::updateControls(ControlList *ctrls,
 
 /**
  * \brief Slot to handle V4L2 events from the V4L2 device
- * \param[in] notifier The event notifier
  *
  * When this slot is called, a V4L2 event is available to be dequeued from the
  * device.
  */
-void V4L2Device::eventAvailable([[maybe_unused]] EventNotifier *notifier)
+void V4L2Device::eventAvailable()
 {
 	struct v4l2_event event{};
 	int ret = ioctl(VIDIOC_DQEVENT, &event);

src/libcamera/v4l2_videodevice.cpp

@@ -1524,7 +1524,6 @@ int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
 
 /**
  * \brief Slot to handle completed buffer events from the V4L2 video device
- * \param[in] notifier The event notifier
  *
  * When this slot is called, a Buffer has become available from the device, and
  * will be emitted through the bufferReady Signal.
@@ -1532,7 +1531,7 @@ int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
  * For Capture video devices the FrameBuffer will contain valid data.
  * For Output video devices the FrameBuffer can be considered empty.
  */
-void V4L2VideoDevice::bufferAvailable([[maybe_unused]] EventNotifier *notifier)
+void V4L2VideoDevice::bufferAvailable()
 {
 	FrameBuffer *buffer = dequeueBuffer();
 	if (!buffer)