[PATCH 3/8] libcamera: pipeline_handler: Add metadataAvailable() function
Cheng-Hao Yang
chenghaoyang at chromium.org
Fri Jan 3 22:26:15 CET 2025
Hi Jacopo,
On Fri, Jan 3, 2025 at 6:08 PM Jacopo Mondi
<jacopo.mondi at ideasonboard.com> wrote:
>
> 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 ?
Ah got it, thanks for the explanation. I guess using rvalue reference
here (Control<T> &&ctrl) and expecting move semantics of users is an
overkill? Fine with the current way though.
>
> > 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 ?
Hmm, Control classes in libcamera have always been a headache to me,
while I thought that ControlList is just a list of `pair<Control<T>,
T>`...? (Observed as `void ControlList::set(const Control<T> &ctrl,
const V &value)`)
>
> 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
nit: I think `should` is a relatively strong term. Some pipeline
handlers might still be calling it once at the end of a Request?
> > > + * 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
nit: s/operations/operation
> > > + * 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);
If we're ignoring the whole `metadata` above when `ids.empty() ==
true`, why do we still want to merge the ids that are not listed in
`idmap`?
I suggest setting the valid id & value pairs in the for loop instead. WDYT?
BR,
Harvey
> > > +
> > > + 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
> > >
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