[PATCH 3/8] libcamera: pipeline_handler: Add metadataAvailable() function

[Jacopo Mondi]

Hi Harvey

On Thu, Jan 02, 2025 at 05:13:36PM +0100, Cheng-Hao Yang wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Fri, Dec 6, 2024 at 5:07 PM Jacopo Mondi
> <jacopo.mondi at ideasonboard.com> wrote:
> >
> > Currently the way pipeline handlers have to store metadata results
> > for a Request is to access the Request::metadata_ list directly and
> > either merge a ControlList or set a single control value there.
> >
> > Direct access to Request::metadata_ is however problematic as even if
> > metadata would be available earlier, pipeline handlers can only
> > accumulate the results in Request::metadata_ and they're only available
> > for applications at Request complete time.
> >
> > Instead of letting pipeline handlers access Request::metadata_ directly
> > provide two helper functions, similar in spirit to
> > PipelineHandler::completeBuffer() and
> > PipelineHandler::completeRequest(), to allow pipeline handlers to
> > notify early availability of metadata.
> >
> > Provide two overloads, one that accepts a ControlList and merges it into
> > Request::metadata_ and one that allows to set a single metadata result
> > there without going through an intermediate copy.
> >
> > The newly provided helpers trigger the Camera::availableMetadata signal
> > from where applications can retrieve the list of ControlIds that have
> > just been made available by the pipeline handler.
> >
> > Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> > ---
> >  include/libcamera/internal/pipeline_handler.h | 41 ++++++++++
> >  src/libcamera/pipeline_handler.cpp            | 74 +++++++++++++++++++
> >  2 files changed, 115 insertions(+)
> >
> > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
> > index fb28a18d0f46..3ca6a0290b2b 100644
> > --- a/include/libcamera/internal/pipeline_handler.h
> > +++ b/include/libcamera/internal/pipeline_handler.h
> > @@ -11,13 +11,17 @@
> >  #include <queue>
> >  #include <string>
> >  #include <sys/types.h>
> > +#include <unordered_set>
> >  #include <vector>
> >
> >  #include <libcamera/base/object.h>
> >
> > +#include <libcamera/camera.h>
> >  #include <libcamera/controls.h>
> >  #include <libcamera/stream.h>
> >
> > +#include "libcamera/internal/request.h"
> > +
> >  namespace libcamera {
> >
> >  class Camera;
> > @@ -58,6 +62,43 @@ public:
> >         void registerRequest(Request *request);
> >         void queueRequest(Request *request);
> >
> > +       void metadataAvailable(Request *request, const ControlList &metadata);
> > +
> > +       template<typename T>
> > +       void metadataAvailable(Request *request, const Control<T> &ctrl,
> > +                              const T &value)
> > +       {
> > +               if (request->metadata().contains(ctrl.id()))
> > +                       return;
> > +
> > +               std::unordered_set<const ControlId *> ids;
> > +               ids.insert(&ctrl);
> > +
> > +               request->metadata().set<T, T>(ctrl, value);
> > +
> > +               Camera *camera = request->_d()->camera();
> > +               camera->metadataAvailable.emit(request, ids);
> > +       }
>
> One question: Have you considered wrapping `ctrls` and `value` into a
> ControlList, and reuse `void metadataAvailable(Request *request, const
> ControlList &metadata)` above?

If memory doesn't fail me, to wrap them I should create a ControlList
and set(), going through a copy, doesn't I ?

> I think this function doesn't check `request->metadata()->idMap()`
> while the above function does.

I think it's fine. In the templated versions ctrl is a Control<T>,
while in

void PipelineHandler::metadataAvailable(Request *request, const ControlList &metadata)

ctrl is an int, that's why I need to go through an id map.

Do you agree ?

Thanks
  j

>
> Same for the function below.
>
> BR,
> Harvey
>
>
> > +
> > +#ifndef __DOXYGEN__
> > +       template<typename T, std::size_t Size>
> > +       void metadataAvailable(Request *request,
> > +                              const Control<Span<const T, Size>> &ctrl,
> > +                              const Span<const T, Size> &value)
> > +       {
> > +               if (request->metadata().contains(ctrl.id()))
> > +                       return;
> > +
> > +               std::unordered_set<const ControlId *> ids;
> > +               ids.insert(&ctrl);
> > +
> > +               request->metadata().set(ctrl, value);
> > +
> > +               Camera *camera = request->_d()->camera();
> > +               camera->metadataAvailable.emit(request, ids);
> > +       }
> > +#endif
> > +
> >         bool completeBuffer(Request *request, FrameBuffer *buffer);
> >         void completeRequest(Request *request);
> >         void cancelRequest(Request *request);
> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > index caa5c20e7483..a69d789116ad 100644
> > --- a/src/libcamera/pipeline_handler.cpp
> > +++ b/src/libcamera/pipeline_handler.cpp
> > @@ -507,6 +507,80 @@ void PipelineHandler::doQueueRequests()
> >   * \return 0 on success or a negative error code otherwise
> >   */
> >
> > +/**
> > + * \brief Notify the availability of a list of metadata for \a request
> > + * \param[in] request The request the metadata belongs to
> > + * \param[in] metadata The metadata list
> > + *
> > + * This function should be called multiple times by pipeline handlers to signal
> > + * the availability of a list of metadata results. It notifies applications
> > + * by triggering the Camera::availableMetadata signal and accumulates the
> > + * metadata results in Request::metadata().
> > + *
> > + * Early metadata completion allows pipeline handlers to fast track delivery of
> > + * metadata results as soon as they are available before the completion of \a
> > + * request. The full list of metadata results of a Request is available at
> > + * Request completion time in Request::metadata().
> > + *
> > + * A metadata key is expected to be notified at most once. Metadata keys
> > + * notified multiple times are ignored.
> > + *
> > + * This overload allows to signal the availability of a list of metadata and
> > + * merges them in the Request::metadata() list. This operations is expensive
> > + * as controls are copied from \a metadata to Request::metadata().
> > + *
> > + * \context This function shall be called from the CameraManager thread.
> > + */
> > +void PipelineHandler::metadataAvailable(Request *request, const ControlList &metadata)
> > +{
> > +       std::unordered_set<const ControlId *> ids;
> > +       const ControlIdMap *idmap = request->metadata().idMap();
> > +
> > +       for (const auto &ctrl : metadata) {
> > +               if (request->metadata().contains(ctrl.first))
> > +                       continue;
> > +
> > +               ASSERT(idmap->count(ctrl.first));
> > +
> > +               ids.insert(idmap->at(ctrl.first));
> > +       }
> > +
> > +       if (ids.empty())
> > +               return;
> > +
> > +       request->metadata().merge(metadata);
> > +
> > +       Camera *camera = request->_d()->camera();
> > +       camera->metadataAvailable.emit(request, ids);
> > +}
> > +
> > +/**
> > + * \fn void PipelineHandler::metadataAvailable(Request *request, const Control<T> &ctrl, const T &value)
> > + * \brief Notify the availability of a metadata result for \a request
> > + * \param[in] request The request the metadata belongs to
> > + * \param[in] ctrl The control id to notify
> > + * \param[in] value the control value
> > + *
> > + * This function should be called multiple times by pipeline handlers to signal
> > + * the availability of a metadata result. It notifies applications
> > + * by triggering the Camera::availableMetadata signal and accumulates the
> > + * metadata result in Request::metadata().
> > + *
> > + * Early metadata completion allows pipeline handlers to fast track delivery of
> > + * metadata results as soon as they are available before the completion of \a
> > + * request. The full list of metadata results of a Request is available at
> > + * Request completion time in Request::metadata().
> > + *
> > + * A metadata key is expected to be notified at most once. Metadata keys
> > + * notified multiple times are ignored.
> > + *
> > + * This overload allows to signal the availability of a single metadata and
> > + * merge \a value in the Request::metadata() list. This operations copies \a
> > + * value in the Request::metadata() list without creating intermediate copies.
> > + *
> > + * \context This function shall be called from the CameraManager thread.
> > + */
> > +
> >  /**
> >   * \brief Complete a buffer for a request
> >   * \param[in] request The request the buffer belongs to
> > --
> > 2.47.1
> >