[PATCH 1/1] libcamera: Camera: Add signals for completion of metadata as a partial result

[Cheng-Hao Yang]

Gentle ping: May we review this patch recently, so that I can continue
uploading the corresponding patches in Android Adapter?
Thanks :)

BR,
Harvey

On Thu, Sep 12, 2024 at 12:57 PM Harvey Yang <chenghaoyang at chromium.org> wrote:
>
> From: Han-Lin Chen <hanlinchen at chromium.org>
>
> Allows pipeline handler to signal metadata completion by adding the
> following signals to Camera:
>
> Signal<Request *, const ControlList &> metadataCompleted;
>
> Together with the bufferCompleted signal, the pipeline handler is allowed to
> return buffers and partial metadata at any stage of processing.
>
> Signed-off-by: Han-Lin Chen <hanlinchen at chromium.org>
> Co-developed-by: Harvey Yang <chenghaoyang at chromium.org>
> ---
>  include/libcamera/camera.h                    |  1 +
>  include/libcamera/internal/pipeline_handler.h |  1 +
>  include/libcamera/request.h                   |  5 +++
>  src/libcamera/camera.cpp                      |  6 +++
>  src/libcamera/pipeline_handler.cpp            | 37 +++++++++++++++++++
>  src/libcamera/request.cpp                     | 20 ++++++++++
>  6 files changed, 70 insertions(+)
>
> diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
> index 94cee7bd..08c5c58c 100644
> --- a/include/libcamera/camera.h
> +++ b/include/libcamera/camera.h
> @@ -122,6 +122,7 @@ public:
>
>         const std::string &id() const;
>
> +       Signal<Request *, const ControlList &> metadataCompleted;
>         Signal<Request *, FrameBuffer *> bufferCompleted;
>         Signal<Request *> requestCompleted;
>         Signal<> disconnected;
> diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
> index 0d380803..1af63a23 100644
> --- a/include/libcamera/internal/pipeline_handler.h
> +++ b/include/libcamera/internal/pipeline_handler.h
> @@ -58,6 +58,7 @@ public:
>         void registerRequest(Request *request);
>         void queueRequest(Request *request);
>
> +       void completeMetadata(Request *request, const ControlList &metadata);
>         bool completeBuffer(Request *request, FrameBuffer *buffer);
>         void completeRequest(Request *request);
>
> diff --git a/include/libcamera/request.h b/include/libcamera/request.h
> index e214a9d1..0200f4a1 100644
> --- a/include/libcamera/request.h
> +++ b/include/libcamera/request.h
> @@ -12,6 +12,7 @@
>  #include <ostream>
>  #include <stdint.h>
>  #include <string>
> +#include <unordered_set>
>
>  #include <libcamera/base/class.h>
>  #include <libcamera/base/signal.h>
> @@ -64,6 +65,8 @@ public:
>
>         std::string toString() const;
>
> +       ControlList addCompletedMetadata(const ControlList &metadata);
> +
>  private:
>         LIBCAMERA_DISABLE_COPY(Request)
>
> @@ -73,6 +76,8 @@ private:
>
>         const uint64_t cookie_;
>         Status status_;
> +
> +       std::unordered_set<unsigned int> completedMetadata_;
>  };
>
>  std::ostream &operator<<(std::ostream &out, const Request &r);
> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index a86f552a..5ffae23e 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp
> @@ -892,6 +892,12 @@ const std::string &Camera::id() const
>   * completed
>   */
>
> +/**
> + * \var Camera::metadataCompleted
> + * \brief Signal emitted when some metadata for a request is completed as a
> + * partial result
> + */
> +
>  /**
>   * \var Camera::requestCompleted
>   * \brief Signal emitted when a request queued to the camera has completed
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index e5940469..5d2999cb 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -535,6 +535,28 @@ bool PipelineHandler::completeBuffer(Request *request, FrameBuffer *buffer)
>         return request->_d()->completeBuffer(buffer);
>  }
>
> +/**
> + * \brief Complete part of metadata for a request
> + * \param[in] request The request the buffer belongs to
> + * \param[in] metadata The partial metadata that has completed
> + *
> + * This function could be called by pipeline handlers to signal completion of
> + * the \a metadata part of the \a request. It notifies applications of metadata
> + * completion.
> + *
> + * \context This function shall be called from the CameraManager thread.
> + */
> +void PipelineHandler::completeMetadata(Request *request, const ControlList &metadata)
> +{
> +       const ControlList &validMetadata = request->addCompletedMetadata(metadata);
> +       if (!validMetadata.empty()) {
> +               request->metadata().merge(validMetadata);
> +
> +               Camera *camera = request->_d()->camera();
> +               camera->metadataCompleted.emit(request, validMetadata);
> +       }
> +}
> +
>  /**
>   * \brief Signal request completion
>   * \param[in] request The request that has completed
> @@ -557,6 +579,21 @@ void PipelineHandler::completeRequest(Request *request)
>
>         Camera::Private *data = camera->_d();
>
> +       /*
> +        * Collect metadata which is not yet completed by the Camera, and
> +        * create one partial result to cover the missing metadata before
> +        * completing the whole request. This guarantees the aggregation of
> +        * metadata in completed partial results equals to the global metadata
> +        * in the request.
> +        *
> +        * \todo: Forbid merging metadata into request.metadata() directly and
> +        * force calling completeMetadata() to report metadata.
> +        */
> +       const ControlList &validMetadata = request->addCompletedMetadata(
> +               request->metadata());
> +       if (!validMetadata.empty())
> +               camera->metadataCompleted.emit(request, validMetadata);
> +
>         while (!data->queuedRequests_.empty()) {
>                 Request *req = data->queuedRequests_.front();
>                 if (req->status() == Request::RequestPending)
> diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
> index 8c56ed30..3ce23a8e 100644
> --- a/src/libcamera/request.cpp
> +++ b/src/libcamera/request.cpp
> @@ -598,6 +598,26 @@ std::string Request::toString() const
>         return ss.str();
>  }
>
> +/**
> + * \brief Add completed metadata, as a partial result
> + * \param[in] metadata The metadata completed
> + *
> + * Request will record the entries that has been sent to the application, to
> + * prevent duplicated controls.
> + *
> + * \return ControlList that hasn't been completed before
> + */
> +ControlList Request::addCompletedMetadata(const ControlList &metadata)
> +{
> +       ControlList resultMetadata;
> +       for (auto &[id, value] : metadata) {
> +               if (!completedMetadata_.count(id))
> +                       resultMetadata.set(id, value);
> +       }
> +
> +       return resultMetadata;
> +}
> +
>  /**
>   * \brief Insert a text representation of a Request into an output stream
>   * \param[in] out The output stream
> --
> 2.46.0.598.g6f2099f65c-goog
>