[libcamera-devel] [PATCH v1 21/23] gst: pad: Add method to store retrieve pending buffers

[Laurent Pinchart]

Hi Nicolas,

Thank you for the patch.

On Tue, Jan 28, 2020 at 10:32:08PM -0500, Nicolas Dufresne wrote:
> From: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> 
> These will be useful for streaming. The requestComplete callback will
> store the buffers on each pads so that the _run() can pick them up
> and push them through the pads from a streaming thread.
> 
> Signed-off-by: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> ---
>  src/gstreamer/gstlibcamerapad.cpp | 28 ++++++++++++++++++++++++++++
>  src/gstreamer/gstlibcamerapad.h   |  4 ++++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/src/gstreamer/gstlibcamerapad.cpp b/src/gstreamer/gstlibcamerapad.cpp
> index 6401810..4a775e4 100644
> --- a/src/gstreamer/gstlibcamerapad.cpp
> +++ b/src/gstreamer/gstlibcamerapad.cpp
> @@ -17,6 +17,7 @@ struct _GstLibcameraPad {
>  	GstPad parent;
>  	StreamRole role;
>  	GstLibcameraPool *pool;
> +	GQueue pending_buffers;
>  };
>  
>  enum {
> @@ -136,3 +137,30 @@ gst_libcamera_pad_get_stream(GstPad *pad)
>  
>  	return nullptr;
>  }
> +
> +void
> +gst_libcamera_pad_queue_buffer(GstPad *pad, GstBuffer *buffer)
> +{
> +	GST_OBJECT_LOCKER(pad);
> +	auto *self = GST_LIBCAMERA_PAD(pad);
> +
> +	g_queue_push_head(&self->pending_buffers, buffer);
> +}
> +
> +GstFlowReturn
> +gst_libcamera_pad_push_pending(GstPad *pad)
> +{
> +	auto *self = GST_LIBCAMERA_PAD(pad);
> +	GstBuffer *buffer;
> +	GstFlowReturn ret = GST_FLOW_CUSTOM_SUCCESS;
> +
> +	{
> +		GST_OBJECT_LOCKER(self);
> +		buffer = (GstBuffer *)g_queue_pop_tail(&self->pending_buffers);
> +	}
> +
> +	if (buffer)
> +		ret = gst_pad_push(pad, buffer);
> +
> +	return ret;

You could write this

	if (!buffer)
		return GST_FLOW_CUSTOM_SUCCESS;

	return gst_pad_push(pad, buffer);

and drop the ret variable.

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

> +}
> diff --git a/src/gstreamer/gstlibcamerapad.h b/src/gstreamer/gstlibcamerapad.h
> index 81d0d58..d928570 100644
> --- a/src/gstreamer/gstlibcamerapad.h
> +++ b/src/gstreamer/gstlibcamerapad.h
> @@ -26,4 +26,8 @@ void gst_libcamera_pad_set_pool(GstPad *pad, GstLibcameraPool *pool);
>  
>  libcamera::Stream *gst_libcamera_pad_get_stream(GstPad *pad);
>  
> +void gst_libcamera_pad_queue_buffer(GstPad *pad, GstBuffer *buffer);
> +
> +GstFlowReturn gst_libcamera_pad_push_pending(GstPad *pad);
> +
>  #endif /* __GST_LIBCAMERA_PAD_H__ */

-- 
Regards,

Laurent Pinchart