[libcamera-devel] [PATCH] libcamera: request: Make Request class Extensible

[Jacopo Mondi]

Hi Laurent,

On Mon, Oct 18, 2021 at 02:54:31PM +0300, Laurent Pinchart wrote:
> Implement the D-Pointer design pattern in the Request class to allow
> changing internal data without affecting the public ABI.
>
> Move a few internal fields that are not needed to implement the public
> API to the Request::Private class already. More fields may be moved
> later.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> I've had this patch in my tree for some time now, and in a recent
> conversation with Jacopo I realized it could be useful to address fence
> handling correctly. It's a bit of a work in progress in the sense that
> it doesn't go through all the members of the Request class to decide
> which ones to move to the private class, but I think it can be built
> upon.

It feels a bit wip as some members have been moved while others have
been not. Not a big deal, we can work on top

> ---
>  include/libcamera/internal/meson.build |  1 +
>  include/libcamera/internal/request.h   | 36 ++++++++++++++++
>  include/libcamera/request.h            |  8 ++--
>  src/libcamera/pipeline_handler.cpp     |  7 +--
>  src/libcamera/request.cpp              | 60 +++++++++++++++++++-------
>  5 files changed, 89 insertions(+), 23 deletions(-)
>  create mode 100644 include/libcamera/internal/request.h
>
> diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
> index 665fd6de4ed3..cae65b0604ff 100644
> --- a/include/libcamera/internal/meson.build
> +++ b/include/libcamera/internal/meson.build
> @@ -34,6 +34,7 @@ libcamera_internal_headers = files([
>      'pipeline_handler.h',
>      'process.h',
>      'pub_key.h',
> +    'request.h',
>      'source_paths.h',
>      'sysfs.h',
>      'v4l2_device.h',
> diff --git a/include/libcamera/internal/request.h b/include/libcamera/internal/request.h
> new file mode 100644
> index 000000000000..ca954f06f497
> --- /dev/null
> +++ b/include/libcamera/internal/request.h
> @@ -0,0 +1,36 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2019, Google Inc.

Is it worth to update copyright year ?

> + *
> + * request.h - Request class private data
> + */
> +#ifndef __LIBCAMERA_INTERNAL_REQUEST_H__
> +#define __LIBCAMERA_INTERNAL_REQUEST_H__
> +
> +#include <libcamera/request.h>
> +
> +namespace libcamera {
> +
> +class Camera;
> +class CameraControlValidator;
> +class FrameBuffer;

FrameBuffer is not used

Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
   j


> +
> +class Request::Private : public Extensible::Private
> +{
> +	LIBCAMERA_DECLARE_PUBLIC(Request)
> +
> +public:
> +	Private(Camera *camera);
> +	~Private();
> +
> +	Camera *camera() const { return camera_; }
> +
> +private:
> +	Camera *camera_;
> +	CameraControlValidator *validator_;
> +	bool cancelled_;
> +};
> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_INTERNAL_REQUEST_H__ */
> diff --git a/include/libcamera/request.h b/include/libcamera/request.h
> index 2d361c9d97dc..e378355f18fc 100644
> --- a/include/libcamera/request.h
> +++ b/include/libcamera/request.h
> @@ -21,12 +21,13 @@
>  namespace libcamera {
>
>  class Camera;
> -class CameraControlValidator;
>  class FrameBuffer;
>  class Stream;
>
> -class Request
> +class Request : public Extensible
>  {
> +	LIBCAMERA_DECLARE_PRIVATE()
> +
>  public:
>  	enum Status {
>  		RequestPending,
> @@ -70,8 +71,6 @@ private:
>
>  	bool completeBuffer(FrameBuffer *buffer);
>
> -	Camera *camera_;
> -	CameraControlValidator *validator_;
>  	ControlList *controls_;
>  	ControlList *metadata_;
>  	BufferMap bufferMap_;
> @@ -80,7 +79,6 @@ private:
>  	uint32_t sequence_;
>  	const uint64_t cookie_;
>  	Status status_;
> -	bool cancelled_;
>  };
>
>  } /* namespace libcamera */
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index f69c4f03b80f..cada864687ff 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -19,6 +19,7 @@
>  #include "libcamera/internal/camera.h"
>  #include "libcamera/internal/device_enumerator.h"
>  #include "libcamera/internal/media_device.h"
> +#include "libcamera/internal/request.h"
>  #include "libcamera/internal/tracepoints.h"
>
>  /**
> @@ -311,7 +312,7 @@ void PipelineHandler::queueRequest(Request *request)
>  {
>  	LIBCAMERA_TRACEPOINT(request_queue, request);
>
> -	Camera *camera = request->camera_;
> +	Camera *camera = request->_d()->camera();
>  	Camera::Private *data = camera->_d();
>  	data->queuedRequests_.push_back(request);
>
> @@ -360,7 +361,7 @@ void PipelineHandler::queueRequest(Request *request)
>   */
>  bool PipelineHandler::completeBuffer(Request *request, FrameBuffer *buffer)
>  {
> -	Camera *camera = request->camera_;
> +	Camera *camera = request->_d()->camera();
>  	camera->bufferCompleted.emit(request, buffer);
>  	return request->completeBuffer(buffer);
>  }
> @@ -381,7 +382,7 @@ bool PipelineHandler::completeBuffer(Request *request, FrameBuffer *buffer)
>   */
>  void PipelineHandler::completeRequest(Request *request)
>  {
> -	Camera *camera = request->camera_;
> +	Camera *camera = request->_d()->camera();
>
>  	request->complete();
>
> diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
> index f95ce4db5eaa..7863269f3139 100644
> --- a/src/libcamera/request.cpp
> +++ b/src/libcamera/request.cpp
> @@ -19,10 +19,11 @@
>
>  #include "libcamera/internal/camera_controls.h"
>  #include "libcamera/internal/framebuffer.h"
> +#include "libcamera/internal/request.h"
>  #include "libcamera/internal/tracepoints.h"
>
>  /**
> - * \file request.h
> + * \file libcamera/request.h
>   * \brief Describes a frame capture request to be processed by a camera
>   */
>
> @@ -30,6 +31,39 @@ namespace libcamera {
>
>  LOG_DEFINE_CATEGORY(Request)
>
> +/**
> + * \class Request::Private
> + * \brief Request private data
> + *
> + * The Request::Private class stores all private data associated with a
> + * request. It implements the d-pointer design pattern to hide core
> + * Request data from the public API, and exposes utility functions to
> + * internal users of the request (namely the PipelineHandler class and its
> + * subclasses).
> + */
> +
> +Request::Private::Private(Camera *camera)
> +	: camera_(camera), cancelled_(false)
> +{
> +	/**
> +	 * \todo Should the Camera expose a validator instance, to avoid
> +	 * creating a new instance for each request?
> +	 */
> +	validator_ = new CameraControlValidator(camera);
> +}
> +
> +Request::Private::~Private()
> +{
> +	delete validator_;
> +}
> +
> +/**
> + * \fn Request::Private::camera()
> + * \brief Retrieve the camera this request has been queued to
> + * \return The Camera this request has been queued to, or nullptr if the
> + * request hasn't been queued
> + */
> +
>  /**
>   * \enum Request::Status
>   * Request completion status
> @@ -74,15 +108,10 @@ LOG_DEFINE_CATEGORY(Request)
>   * completely opaque to libcamera.
>   */
>  Request::Request(Camera *camera, uint64_t cookie)
> -	: camera_(camera), sequence_(0), cookie_(cookie),
> -	  status_(RequestPending), cancelled_(false)
> +	: Extensible(std::make_unique<Private>(camera)), sequence_(0),
> +	  cookie_(cookie), status_(RequestPending)
>  {
> -	/**
> -	 * \todo Should the Camera expose a validator instance, to avoid
> -	 * creating a new instance for each request?
> -	 */
> -	validator_ = new CameraControlValidator(camera);
> -	controls_ = new ControlList(controls::controls, validator_);
> +	controls_ = new ControlList(controls::controls, _d()->validator_);
>
>  	/**
>  	 * \todo: Add a validator for metadata controls.
> @@ -100,7 +129,6 @@ Request::~Request()
>
>  	delete metadata_;
>  	delete controls_;
> -	delete validator_;
>  }
>
>  /**
> @@ -130,7 +158,7 @@ void Request::reuse(ReuseFlag flags)
>
>  	sequence_ = 0;
>  	status_ = RequestPending;
> -	cancelled_ = false;
> +	_d()->cancelled_ = false;
>
>  	controls_->clear();
>  	metadata_->clear();
> @@ -286,7 +314,7 @@ void Request::complete()
>  	ASSERT(status_ == RequestPending);
>  	ASSERT(!hasPendingBuffers());
>
> -	status_ = cancelled_ ? RequestCancelled : RequestComplete;
> +	status_ = _d()->cancelled_ ? RequestCancelled : RequestComplete;
>
>  	LOG(Request, Debug) << toString();
>
> @@ -303,17 +331,19 @@ void Request::complete()
>   */
>  void Request::cancel()
>  {
> +	Private *const d = _d();
> +
>  	LIBCAMERA_TRACEPOINT(request_cancel, this);
>
>  	ASSERT(status_ == RequestPending);
>
>  	for (FrameBuffer *buffer : pending_) {
>  		buffer->cancel();
> -		camera_->bufferCompleted.emit(this, buffer);
> +		d->camera_->bufferCompleted.emit(this, buffer);
>  	}
>
>  	pending_.clear();
> -	cancelled_ = true;
> +	d->cancelled_ = true;
>  }
>
>  /**
> @@ -339,7 +369,7 @@ bool Request::completeBuffer(FrameBuffer *buffer)
>  	buffer->_d()->setRequest(nullptr);
>
>  	if (buffer->metadata().status == FrameMetadata::FrameCancelled)
> -		cancelled_ = true;
> +		_d()->cancelled_ = true;
>
>  	return !hasPendingBuffers();
>  }
>
> base-commit: 2f75a7e5b8c6258dc12e9e3128cb30133f66b4f9
> --
> Regards,
>
> Laurent Pinchart
>