libcamera: camera: Move private data members to private implementation

Use the d-pointer idiom ([1], [2]) to hide the private data members from
the Camera class interface. This will ease maintaining ABI
compatibility, and prepares for the implementation of the Camera class
threading model.

The FrameBufferAllocator class accesses the Camera private data members
directly. In order to hide them, this pattern is replaced with new
private member functions in the Camera class, and the
FrameBufferAllocator is updated accordingly.

[1] https://wiki.qt.io/D-Pointer
[2] https://en.cppreference.com/w/cpp/language/pimpl

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

3 files changed, 161 insertions, 134 deletions

diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
index 6597ade8..c37319ed 100644
--- a/include/libcamera/camera.h
+++ b/include/libcamera/camera.h
@@ -98,34 +98,22 @@ public:
 	int stop();
 
 private:
-	enum State {
-		CameraAvailable,
-		CameraAcquired,
-		CameraConfigured,
-		CameraRunning,
-	};
-
-	Camera(PipelineHandler *pipe, const std::string &name);
+	Camera(PipelineHandler *pipe, const std::string &name,
+	       const std::set<Stream *> &streams);
 	~Camera();
 
-	bool stateBetween(State low, State high) const;
-	bool stateIs(State state) const;
+	class Private;
+	std::unique_ptr<Private> p_;
 
 	friend class PipelineHandler;
 	void disconnect();
-
 	void requestComplete(Request *request);
 
-	std::shared_ptr<PipelineHandler> pipe_;
-	std::string name_;
-	std::set<Stream *> streams_;
-	std::set<Stream *> activeStreams_;
-
-	bool disconnected_;
-	State state_;
-
-	/* Needed to update allocator_ and to read state_ and activeStreams_. */
 	friend class FrameBufferAllocator;
+	int exportFrameBuffers(Stream *stream,
+			       std::vector<std::unique_ptr<FrameBuffer>> *buffers);
+	int freeFrameBuffers(Stream *stream);
+	/* \todo Remove allocator_ from the exposed API */
 	FrameBufferAllocator *allocator_;
 };
 
diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 79a5f994..d567148c 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -254,6 +254,75 @@ std::size_t CameraConfiguration::size() const
  * \brief The vector of stream configurations
  */
 
+class Camera::Private
+{
+public:
+	enum State {
+		CameraAvailable,
+		CameraAcquired,
+		CameraConfigured,
+		CameraRunning,
+	};
+
+	Private(PipelineHandler *pipe, const std::string &name,
+		const std::set<Stream *> &streams);
+
+	bool stateBetween(State low, State high) const;
+	bool stateIs(State state) const;
+
+	std::shared_ptr<PipelineHandler> pipe_;
+	std::string name_;
+	std::set<Stream *> streams_;
+	std::set<Stream *> activeStreams_;
+
+	bool disconnected_;
+	State state_;
+};
+
+Camera::Private::Private(PipelineHandler *pipe, const std::string &name,
+			 const std::set<Stream *> &streams)
+	: pipe_(pipe->shared_from_this()), name_(name), streams_(streams),
+	  disconnected_(false), state_(CameraAvailable)
+{
+}
+
+static const char *const camera_state_names[] = {
+	"Available",
+	"Acquired",
+	"Configured",
+	"Running",
+};
+
+bool Camera::Private::stateBetween(State low, State high) const
+{
+	if (state_ >= low && state_ <= high)
+		return true;
+
+	ASSERT(static_cast<unsigned int>(low) < ARRAY_SIZE(camera_state_names) &&
+	       static_cast<unsigned int>(high) < ARRAY_SIZE(camera_state_names));
+
+	LOG(Camera, Debug) << "Camera in " << camera_state_names[state_]
+			   << " state trying operation requiring state between "
+			   << camera_state_names[low] << " and "
+			   << camera_state_names[high];
+
+	return false;
+}
+
+bool Camera::Private::stateIs(State state) const
+{
+	if (state_ == state)
+		return true;
+
+	ASSERT(static_cast<unsigned int>(state) < ARRAY_SIZE(camera_state_names));
+
+	LOG(Camera, Debug) << "Camera in " << camera_state_names[state_]
+			   << " state trying operation requiring state "
+			   << camera_state_names[state];
+
+	return false;
+}
+
 /**
  * \class Camera
  * \brief Camera device
@@ -354,8 +423,7 @@ std::shared_ptr<Camera> Camera::create(PipelineHandler *pipe,
 		}
 	};
 
-	Camera *camera = new Camera(pipe, name);
-	camera->streams_ = streams;
+	Camera *camera = new Camera(pipe, name, streams);
 
 	return std::shared_ptr<Camera>(camera, Deleter());
 }
@@ -366,7 +434,7 @@ std::shared_ptr<Camera> Camera::create(PipelineHandler *pipe,
  */
 const std::string &Camera::name() const
 {
-	return name_;
+	return p_->name_;
 }
 
 /**
@@ -392,55 +460,18 @@ const std::string &Camera::name() const
  * application API calls by returning errors immediately.
  */
 
-Camera::Camera(PipelineHandler *pipe, const std::string &name)
-	: pipe_(pipe->shared_from_this()), name_(name), disconnected_(false),
-	  state_(CameraAvailable), allocator_(nullptr)
+Camera::Camera(PipelineHandler *pipe, const std::string &name,
+	       const std::set<Stream *> &streams)
+	: p_(new Private(pipe, name, streams)), allocator_(nullptr)
 {
 }
 
 Camera::~Camera()
 {
-	if (!stateIs(CameraAvailable))
+	if (!p_->stateIs(Private::CameraAvailable))
 		LOG(Camera, Error) << "Removing camera while still in use";
 }
 
-static const char *const camera_state_names[] = {
-	"Available",
-	"Acquired",
-	"Configured",
-	"Running",
-};
-
-bool Camera::stateBetween(State low, State high) const
-{
-	if (state_ >= low && state_ <= high)
-		return true;
-
-	ASSERT(static_cast<unsigned int>(low) < ARRAY_SIZE(camera_state_names) &&
-	       static_cast<unsigned int>(high) < ARRAY_SIZE(camera_state_names));
-
-	LOG(Camera, Debug) << "Camera in " << camera_state_names[state_]
-			   << " state trying operation requiring state between "
-			   << camera_state_names[low] << " and "
-			   << camera_state_names[high];
-
-	return false;
-}
-
-bool Camera::stateIs(State state) const
-{
-	if (state_ == state)
-		return true;
-
-	ASSERT(static_cast<unsigned int>(state) < ARRAY_SIZE(camera_state_names));
-
-	LOG(Camera, Debug) << "Camera in " << camera_state_names[state_]
-			   << " state trying operation requiring state "
-			   << camera_state_names[state];
-
-	return false;
-}
-
 /**
  * \brief Notify camera disconnection
  *
@@ -455,20 +486,45 @@ bool Camera::stateIs(State state) const
  */
 void Camera::disconnect()
 {
-	LOG(Camera, Debug) << "Disconnecting camera " << name_;
+	LOG(Camera, Debug) << "Disconnecting camera " << name();
 
 	/*
 	 * If the camera was running when the hardware was removed force the
 	 * state to Configured state to allow applications to free resources
 	 * and call release() before deleting the camera.
 	 */
-	if (state_ == CameraRunning)
-		state_ = CameraConfigured;
+	if (p_->state_ == Private::CameraRunning)
+		p_->state_ = Private::CameraConfigured;
 
-	disconnected_ = true;
+	p_->disconnected_ = true;
 	disconnected.emit(this);
 }
 
+int Camera::exportFrameBuffers(Stream *stream,
+			       std::vector<std::unique_ptr<FrameBuffer>> *buffers)
+{
+	if (!p_->stateIs(Private::CameraConfigured))
+		return -EACCES;
+
+	if (streams().find(stream) == streams().end())
+		return -EINVAL;
+
+	if (p_->activeStreams_.find(stream) == p_->activeStreams_.end())
+		return -EINVAL;
+
+	return p_->pipe_->exportFrameBuffers(this, stream, buffers);
+}
+
+int Camera::freeFrameBuffers(Stream *stream)
+{
+	if (!p_->stateIs(Private::CameraConfigured))
+		return -EACCES;
+
+	p_->pipe_->freeFrameBuffers(this, stream);
+
+	return 0;
+}
+
 /**
  * \brief Acquire the camera device for exclusive access
  *
@@ -494,19 +550,19 @@ void Camera::disconnect()
  */
 int Camera::acquire()
 {
-	if (disconnected_)
+	if (p_->disconnected_)
 		return -ENODEV;
 
-	if (!stateIs(CameraAvailable))
+	if (!p_->stateIs(Private::CameraAvailable))
 		return -EBUSY;
 
-	if (!pipe_->lock()) {
+	if (!p_->pipe_->lock()) {
 		LOG(Camera, Info)
 			<< "Pipeline handler in use by another process";
 		return -EBUSY;
 	}
 
-	state_ = CameraAcquired;
+	p_->state_ = Private::CameraAcquired;
 
 	return 0;
 }
@@ -524,7 +580,8 @@ int Camera::acquire()
  */
 int Camera::release()
 {
-	if (!stateBetween(CameraAvailable, CameraConfigured))
+	if (!p_->stateBetween(Private::CameraAvailable,
+			      Private::CameraConfigured))
 		return -EBUSY;
 
 	if (allocator_) {
@@ -537,9 +594,9 @@ int Camera::release()
 		return -EBUSY;
 	}
 
-	pipe_->unlock();
+	p_->pipe_->unlock();
 
-	state_ = CameraAvailable;
+	p_->state_ = Private::CameraAvailable;
 
 	return 0;
 }
@@ -553,7 +610,7 @@ int Camera::release()
  */
 const ControlInfoMap &Camera::controls()
 {
-	return pipe_->controls(this);
+	return p_->pipe_->controls(this);
 }
 
 /**
@@ -567,7 +624,7 @@ const ControlInfoMap &Camera::controls()
  */
 const std::set<Stream *> &Camera::streams() const
 {
-	return streams_;
+	return p_->streams_;
 }
 
 /**
@@ -586,10 +643,10 @@ const std::set<Stream *> &Camera::streams() const
  */
 std::unique_ptr<CameraConfiguration> Camera::generateConfiguration(const StreamRoles &roles)
 {
-	if (disconnected_ || roles.size() > streams_.size())
+	if (p_->disconnected_ || roles.size() > streams().size())
 		return nullptr;
 
-	CameraConfiguration *config = pipe_->generateConfiguration(this, roles);
+	CameraConfiguration *config = p_->pipe_->generateConfiguration(this, roles);
 	if (!config) {
 		LOG(Camera, Debug)
 			<< "Pipeline handler failed to generate configuration";
@@ -639,10 +696,11 @@ int Camera::configure(CameraConfiguration *config)
 {
 	int ret;
 
-	if (disconnected_)
+	if (p_->disconnected_)
 		return -ENODEV;
 
-	if (!stateBetween(CameraAcquired, CameraConfigured))
+	if (!p_->stateBetween(Private::CameraAcquired,
+			      Private::CameraConfigured))
 		return -EACCES;
 
 	if (allocator_ && allocator_->allocated()) {
@@ -667,11 +725,11 @@ int Camera::configure(CameraConfiguration *config)
 
 	LOG(Camera, Info) << msg.str();
 
-	ret = pipe_->configure(this, config);
+	ret = p_->pipe_->configure(this, config);
 	if (ret)
 		return ret;
 
-	activeStreams_.clear();
+	p_->activeStreams_.clear();
 	for (const StreamConfiguration &cfg : *config) {
 		Stream *stream = cfg.stream();
 		if (!stream)
@@ -679,10 +737,10 @@ int Camera::configure(CameraConfiguration *config)
 				<< "Pipeline handler failed to update stream configuration";
 
 		stream->configuration_ = cfg;
-		activeStreams_.insert(stream);
+		p_->activeStreams_.insert(stream);
 	}
 
-	state_ = CameraConfigured;
+	p_->state_ = Private::CameraConfigured;
 
 	return 0;
 }
@@ -709,7 +767,9 @@ int Camera::configure(CameraConfiguration *config)
  */
 Request *Camera::createRequest(uint64_t cookie)
 {
-	if (disconnected_ || !stateBetween(CameraConfigured, CameraRunning))
+	if (p_->disconnected_ ||
+	    !p_->stateBetween(Private::CameraConfigured,
+			      Private::CameraRunning))
 		return nullptr;
 
 	return new Request(this, cookie);
@@ -739,10 +799,10 @@ Request *Camera::createRequest(uint64_t cookie)
  */
 int Camera::queueRequest(Request *request)
 {
-	if (disconnected_)
+	if (p_->disconnected_)
 		return -ENODEV;
 
-	if (!stateIs(CameraRunning))
+	if (!p_->stateIs(Private::CameraRunning))
 		return -EACCES;
 
 	if (request->buffers().empty()) {
@@ -753,13 +813,13 @@ int Camera::queueRequest(Request *request)
 	for (auto const &it : request->buffers()) {
 		Stream *stream = it.first;
 
-		if (activeStreams_.find(stream) == activeStreams_.end()) {
+		if (p_->activeStreams_.find(stream) == p_->activeStreams_.end()) {
 			LOG(Camera, Error) << "Invalid request";
 			return -EINVAL;
 		}
 	}
 
-	return pipe_->queueRequest(this, request);
+	return p_->pipe_->queueRequest(this, request);
 }
 
 /**
@@ -777,26 +837,26 @@ int Camera::queueRequest(Request *request)
  */
 int Camera::start()
 {
-	if (disconnected_)
+	if (p_->disconnected_)
 		return -ENODEV;
 
-	if (!stateIs(CameraConfigured))
+	if (!p_->stateIs(Private::CameraConfigured))
 		return -EACCES;
 
 	LOG(Camera, Debug) << "Starting capture";
 
-	for (Stream *stream : activeStreams_) {
+	for (Stream *stream : p_->activeStreams_) {
 		if (allocator_ && !allocator_->buffers(stream).empty())
 			continue;
 
-		pipe_->importFrameBuffers(this, stream);
+		p_->pipe_->importFrameBuffers(this, stream);
 	}
 
-	int ret = pipe_->start(this);
+	int ret = p_->pipe_->start(this);
 	if (ret)
 		return ret;
 
-	state_ = CameraRunning;
+	p_->state_ = Private::CameraRunning;
 
 	return 0;
 }
@@ -815,23 +875,23 @@ int Camera::start()
  */
 int Camera::stop()
 {
-	if (disconnected_)
+	if (p_->disconnected_)
 		return -ENODEV;
 
-	if (!stateIs(CameraRunning))
+	if (!p_->stateIs(Private::CameraRunning))
 		return -EACCES;
 
 	LOG(Camera, Debug) << "Stopping capture";
 
-	state_ = CameraConfigured;
+	p_->state_ = Private::CameraConfigured;
 
-	pipe_->stop(this);
+	p_->pipe_->stop(this);
 
-	for (Stream *stream : activeStreams_) {
+	for (Stream *stream : p_->activeStreams_) {
 		if (allocator_ && !allocator_->buffers(stream).empty())
 			continue;
 
-		pipe_->freeFrameBuffers(this, stream);
+		p_->pipe_->freeFrameBuffers(this, stream);
 	}
 
 	return 0;
diff --git a/src/libcamera/framebuffer_allocator.cpp b/src/libcamera/framebuffer_allocator.cpp
index c772b516..4ced10cd 100644
--- a/src/libcamera/framebuffer_allocator.cpp
+++ b/src/libcamera/framebuffer_allocator.cpp
@@ -89,7 +89,7 @@ FrameBufferAllocator::~FrameBufferAllocator()
 {
 	for (auto &value : buffers_) {
 		Stream *stream = value.first;
-		camera_->pipe_->freeFrameBuffers(camera_.get(), stream);
+		camera_->freeFrameBuffers(stream);
 	}
 
 	buffers_.clear();
@@ -117,32 +117,17 @@ FrameBufferAllocator::~FrameBufferAllocator()
  */
 int FrameBufferAllocator::allocate(Stream *stream)
 {
-	if (camera_->state_ != Camera::CameraConfigured) {
-		LOG(Allocator, Error)
-			<< "Camera must be in the configured state to allocate buffers";
-		return -EACCES;
-	}
-
-	if (camera_->streams().find(stream) == camera_->streams().end()) {
-		LOG(Allocator, Error)
-			<< "Stream does not belong to " << camera_->name();
-		return -EINVAL;
-	}
-
-	if (camera_->activeStreams_.find(stream) == camera_->activeStreams_.end()) {
-		LOG(Allocator, Error)
-			<< "Stream is not part of " << camera_->name()
-			<< " active configuration";
-		return -EINVAL;
-	}
-
 	if (buffers_.count(stream)) {
 		LOG(Allocator, Error) << "Buffers already allocated for stream";
 		return -EBUSY;
 	}
 
-	return camera_->pipe_->exportFrameBuffers(camera_.get(), stream,
-						  &buffers_[stream]);
+	int ret = camera_->exportFrameBuffers(stream, &buffers_[stream]);
+	if (ret == -EINVAL)
+		LOG(Allocator, Error)
+			<< "Stream is not part of " << camera_->name()
+			<< " active configuration";
+	return ret;
 }
 
 /**
@@ -159,22 +144,16 @@ int FrameBufferAllocator::allocate(Stream *stream)
  */
 int FrameBufferAllocator::free(Stream *stream)
 {
-	if (camera_->state_ != Camera::CameraConfigured) {
-		LOG(Allocator, Error)
-			<< "Camera must be in the configured state to free buffers";
-		return -EACCES;
-	}
-
 	auto iter = buffers_.find(stream);
 	if (iter == buffers_.end())
 		return -EINVAL;
 
-	std::vector<std::unique_ptr<FrameBuffer>> &buffers = iter->second;
+	int ret = camera_->freeFrameBuffers(stream);
+	if (ret < 0)
+		return ret;
 
+	std::vector<std::unique_ptr<FrameBuffer>> &buffers = iter->second;
 	buffers.clear();
-
-	camera_->pipe_->freeFrameBuffers(camera_.get(), stream);
-
 	buffers_.erase(iter);
 
 	return 0;