[libcamera-devel] [PATCH/WIP] libcamera: controls: Add a function to merge two control lists

[Niklas Söderlund]

Hi Laurent,

Thanks for your work.

On 2021-02-22 15:21:21 +0200, Laurent Pinchart wrote:
> Add a new ControlList::merge() function to merge two control lists. The
> semantics is identical to std::unordered_map::merge(). This can be used
> by pipeline handlers to merge metadata they populate with metadata
> received from an IPA.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  include/libcamera/controls.h |  2 ++
>  src/libcamera/controls.cpp   | 20 ++++++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> Hello,
> 
> This may come handy for the IPU3 IPA. The patch hasn't been tested yet,
> I'm in particular not entirely sure of the idmap_ check. I've opted for
> an ASSERT() to be restrictive and catch potential issues, we may decide
> to relax the requirement (or handle it differently) if the assertion is
> triggered and the analysis of the problem shows that a different
> approach is required.

I think it make sens to have an ASSERT() check for this.

Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>

> 
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index 1a5690a5ccbe..16726ce9b1ed 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -363,7 +363,9 @@ public:
>  
>  	bool empty() const { return controls_.empty(); }
>  	std::size_t size() const { return controls_.size(); }
> +
>  	void clear() { controls_.clear(); }
> +	void merge(ControlList &source);
>  
>  	bool contains(const ControlId &id) const;
>  	bool contains(unsigned int id) const;
> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index c58ed3946f3b..58555ea64c95 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -874,6 +874,26 @@ ControlList::ControlList(const ControlInfoMap &infoMap, ControlValidator *valida
>   * \brief Removes all controls from the list
>   */
>  
> +/**
> + * \brief Merge the \a source into the ControlList
> + * \param[in] source The ControlList to merge into this object
> + *
> + * Merging two control lists extracts elements from the \a source and insert
> + * them in *this. If the \a source contains elements whose key is already
> + * present in *this, then those elements are not extracted. The semantics is
> + * identical to std::unordered_map::merge() in that only internal pointers to
> + * nodes are updated, without copying or moving the elements.
> + *
> + * Only control lists created from the same ControlIdMap or ControlInfoMap may
> + * be merged. Attempting to do otherwise results in undefined behaviour.
> + */
> +void ControlList::merge(ControlList &source)
> +{
> +	ASSERT(idmap_ == source.idmap_);
> +
> +	controls_.merge(source.controls_);
> +}
> +
>  /**
>   * \brief Check if the list contains a control with the specified \a id
>   * \param[in] id The control ID
> -- 
> Regards,
> 
> Laurent Pinchart
> 
> _______________________________________________
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> libcamera-devel at lists.libcamera.org
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-- 
Regards,
Niklas Söderlund