[libcamera-devel] [PATCH v2 06/12] libcamera: pipeline_handler: Split request queueing

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Sat, Nov 20, 2021 at 12:13:07PM +0100, Jacopo Mondi wrote:
> In order to prepare to handle synchronization fences at Request
> queueing time, split the PipelineHandler::queueRequest() function in
> two, by creating a list of waiting requests and introducing the
> doQueueRequest() function that queues requests to the device in the
> order the pipeline has received them.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  include/libcamera/internal/pipeline_handler.h |  6 +++++
>  .../libcamera/internal/tracepoints/request.tp |  9 +++++++
>  src/libcamera/pipeline_handler.cpp            | 27 +++++++++++++++++++
>  3 files changed, 42 insertions(+)
> 
> diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
> index 41cba44d990f..608e6f79039f 100644
> --- a/include/libcamera/internal/pipeline_handler.h
> +++ b/include/libcamera/internal/pipeline_handler.h
> @@ -7,6 +7,7 @@
>  #ifndef __LIBCAMERA_INTERNAL_PIPELINE_HANDLER_H__
>  #define __LIBCAMERA_INTERNAL_PIPELINE_HANDLER_H__
>  
> +#include <deque>
>  #include <memory>
>  #include <set>
>  #include <string>
> @@ -76,9 +77,14 @@ private:
>  	void mediaDeviceDisconnected(MediaDevice *media);
>  	virtual void disconnect();
>  
> +	void doQueueRequest(Request *request);
> +	void doQueueRequests();
> +
>  	std::vector<std::shared_ptr<MediaDevice>> mediaDevices_;
>  	std::vector<std::weak_ptr<Camera>> cameras_;
>  
> +	std::deque<Request *> waitingRequests_;

Can you use a std::queue ?

> +
>  	const char *name_;
>  
>  	friend class PipelineHandlerFactory;
> diff --git a/include/libcamera/internal/tracepoints/request.tp b/include/libcamera/internal/tracepoints/request.tp
> index 37cd2f8864ce..87219b8d8e6f 100644
> --- a/include/libcamera/internal/tracepoints/request.tp
> +++ b/include/libcamera/internal/tracepoints/request.tp
> @@ -58,6 +58,15 @@ TRACEPOINT_EVENT_INSTANCE(
>  	)
>  )
>  
> +TRACEPOINT_EVENT_INSTANCE(
> +	libcamera,
> +	request,
> +	request_device_queue,

Maybe request_queue_device ?

> +	TP_ARGS(
> +		libcamera::Request *, req
> +	)
> +)
> +
>  TRACEPOINT_EVENT_INSTANCE(
>  	libcamera,
>  	request,
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 67fdf1d8db01..b8dd03647954 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -312,6 +312,17 @@ void PipelineHandler::queueRequest(Request *request)
>  {
>  	LIBCAMERA_TRACEPOINT(request_queue, request);
>  
> +	waitingRequests_.push_back(request);
> +	doQueueRequests();
> +}
> +
> +/**
> + * \brief Queue one requests to the device
> + */
> +void PipelineHandler::doQueueRequest(Request *request)
> +{
> +	LIBCAMERA_TRACEPOINT(request_device_queue, request);
> +
>  	Camera *camera = request->_d()->camera();
>  	Camera::Private *data = camera->_d();
>  	data->queuedRequests_.push_back(request);
> @@ -325,6 +336,22 @@ void PipelineHandler::queueRequest(Request *request)
>  	}
>  }
>  
> +/**
> + * \brief Queue requests to the device

We need more documentation here and for doQueueRequest(), to explain how
fences and requests are handled.

> + */
> +void PipelineHandler::doQueueRequests()
> +{
> +	while (true) {
> +		if (waitingRequests_.empty())
> +			return;
> +
> +		Request *request = waitingRequests_.front();
> +		waitingRequests_.pop_front();
> +
> +		doQueueRequest(request);
> +	}
> +}
> +
>  /**
>   * \fn PipelineHandler::queueRequestDevice()
>   * \brief Queue a request to the device

-- 
Regards,

Laurent Pinchart