[libcamera-devel] [PATCH 1/3] libcamera: pipeline_handler: Make cameraData() a const operation

Niklas Söderlund niklas.soderlund at ragnatech.se
Fri Aug 14 12:18:55 CEST 2020


Hi Laurent,

Thanks for your feedback.

On 2020-08-14 12:35:32 +0300, Laurent Pinchart wrote:
> Hi Niklas,
> 
> Thank you for the patch.
> 
> On Thu, Aug 06, 2020 at 02:53:28PM +0200, Niklas Söderlund wrote:
> > There is nothing blocking cameraData() from being a constant operation.
> > The assert already enforces that a std::map::at() operation would always
> > succeed. Switch to using at() and mark the method as a const operation.
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> > ---
> >  include/libcamera/internal/pipeline_handler.h | 2 +-
> >  src/libcamera/pipeline_handler.cpp            | 4 ++--
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
> > index 22e629a8401d1e4e..d5321ef56df358d0 100644
> > --- a/include/libcamera/internal/pipeline_handler.h
> > +++ b/include/libcamera/internal/pipeline_handler.h
> > @@ -96,7 +96,7 @@ protected:
> >  
> >  	virtual int queueRequestDevice(Camera *camera, Request *request) = 0;
> >  
> > -	CameraData *cameraData(const Camera *camera);
> > +	CameraData *cameraData(const Camera *camera) const;
> 
> CameraData holds part of the pipeline state. As such, returning a
> non-const pointer from a const function, while not breaking compilation,
> conceptually breaks const-correctness.
> 
> Would it be enough for your use case to have both
> 
> 	CameraData *cameraData(const Camera *camera);
> 	const CameraData *cameraData(const Camera *camera) const;
> 
> ?

Thanks for spotting this, not sure how this brain fart happened. Your 
proposed change solves my issue in a nicer and foremost correct way, 
will send a v2.

> 
> >  
> >  	CameraManager *manager_;
> >  
> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > index ccd45edc847b9e3f..bc9c1d4b09c5437d 100644
> > --- a/src/libcamera/pipeline_handler.cpp
> > +++ b/src/libcamera/pipeline_handler.cpp
> > @@ -595,10 +595,10 @@ void PipelineHandler::disconnect()
> >   * valid until the pipeline handler is destroyed. It shall not be deleted
> >   * manually by the caller.
> >   */
> > -CameraData *PipelineHandler::cameraData(const Camera *camera)
> > +CameraData *PipelineHandler::cameraData(const Camera *camera) const
> >  {
> >  	ASSERT(cameraData_.count(camera));
> > -	return cameraData_[camera].get();
> > +	return cameraData_.at(camera).get();
> >  }
> >  
> >  /**
> 
> -- 
> Regards,
> 
> Laurent Pinchart

-- 
Regards,
Niklas Söderlund


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