[libcamera-devel] [PATCH v3 24/30] py: MappedFrameBuffer: Support non-contextmanager use

[Laurent Pinchart]

Hi Tomi,

Thank you for the patch.

On Fri, May 27, 2022 at 05:44:41PM +0300, Tomi Valkeinen wrote:
> Implement non-contextmanager use to MappedFrameBuffer so that we can
> either:
> 
> with MappedFrameBuffer(fb) as mfb:
> 	...
> 
> or
> 
> mfb = MappedFrameBuffer(fb)
> mfb.mmap()
> ...
> mfb.munmap()
> 
> While at it, improve the error handling a bit.
> 
> Note that the mmap() returns self. In other words, one can do this:
> 
> mfb = MappedFrameBuffer(fb).mmap()
> ...
> mfb.munmap()
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> ---
>  src/py/libcamera/utils/MappedFrameBuffer.py | 22 ++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/src/py/libcamera/utils/MappedFrameBuffer.py b/src/py/libcamera/utils/MappedFrameBuffer.py
> index 69315e76..4b20f904 100644
> --- a/src/py/libcamera/utils/MappedFrameBuffer.py
> +++ b/src/py/libcamera/utils/MappedFrameBuffer.py
> @@ -10,8 +10,19 @@ class MappedFrameBuffer:
>      """
>      def __init__(self, fb: libcamera.FrameBuffer):
>          self.__fb = fb
> +        self.__planes = ()
> +        self.__maps = ()
>  
>      def __enter__(self):
> +        return self.mmap()
> +
> +    def __exit__(self, exc_type, exc_value, exc_traceback):
> +        self.munmap()
> +
> +    def mmap(self):
> +        if self.__planes:
> +            raise RuntimeError('MappedFrameBuffer already mmapped')
> +
>          import os
>          import mmap
>  
> @@ -68,14 +79,23 @@ class MappedFrameBuffer:
>  
>          return self
>  
> -    def __exit__(self, exc_type, exc_value, exc_traceback):
> +    def munmap(self):
> +        if not self.__planes:
> +            raise RuntimeError('MappedFrameBuffer not mmapped')
> +
>          for p in self.__planes:
>              p.release()
>  
>          for mm in self.__maps:
>              mm.close()
>  
> +        self.__planes = ()
> +        self.__maps = ()
> +
>      @property
>      def planes(self) -> Tuple[memoryview, ...]:
>          """memoryviews for the planes"""
> +        if not self.__planes:
> +            raise RuntimeError('MappedFrameBuffer not mmapped')
> +
>          return self.__planes

-- 
Regards,

Laurent Pinchart