[libcamera-devel] [PATCH v2 3/3] android: camera_device: Send capture results by inspecting the queue

[Umang Jain]

Hi

On 9/29/21 3:00 AM, Laurent Pinchart wrote:
> Hi Umang,
>
> Thank you for the patch.
>
> On Tue, Sep 28, 2021 at 09:55:36PM +0530, Umang Jain wrote:
>> There is a possibility that an out-of-order completion of capture
>> request happens by calling process_capture_result() directly on error
>> paths. The framework expects that errors should be notified as soon as
>> possible, but the request completion order should remain intact.
>> An existing instance of this is abortRequest(), which sends the capture
>> results on flushing state, without considering order-of-completion.
>>
>> Since we have a queue of Camera3RequestDescriptor tracking each
>> capture request placed by framework to libcamera HAL, we should be only
>> sending back capture results from a single location, by inspecting
>> the queue. As per the patch, this now happens in
>> CameraDevice::sendCaptureResults().
>>
>> Each descriptor is now equipped with its own status to denote whether
>> the capture request is complete and ready to send back to the framework
>> or needs to be waited upon. This ensures that the order of completion is
>> respected for the requests.
>>
>> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
>> ---
>>   src/android/camera_device.cpp | 44 +++++++++++++++++++++++++----------
>>   src/android/camera_device.h   | 15 +++++++++++-
>>   2 files changed, 46 insertions(+), 13 deletions(-)
>>
>> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
>> index a3b8a549..83030366 100644
>> --- a/src/android/camera_device.cpp
>> +++ b/src/android/camera_device.cpp
>> @@ -861,11 +861,12 @@ int CameraDevice::processControls(Camera3RequestDescriptor *descriptor)
>>   	return 0;
>>   }
>>   
>> -void CameraDevice::abortRequest(camera3_capture_request_t *request)
>> +void CameraDevice::abortRequest(Camera3RequestDescriptor *descriptor,
>> +				camera3_capture_request_t *request)
> I don't think I've seen a reply to my review comment in v1:


Oh, I think I did reply and had a brief discussion with you about it on 
IRC. Nevermind, I think I got confused a bit yesterday and now I  have 
addressed the comment locally here as well. Works fine.

>
> Could this function take a Camera3RequestDescriptor pointer only ? It
> should contain all the needed data. This can be done as a patch before
> this one if desired, or here as it shouldn't be much extra work.
>
> This function uses the num_output_buffers, frame_number and
> output_buffers members of camera3_capture_request_t. Those are copied to
> the Camera3RequestDescriptor buffers_ and frameNumber_ members which you
> can use here.
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>
>>   {
>>   	notifyError(request->frame_number, nullptr, CAMERA3_MSG_ERROR_REQUEST);
>>   
>> -	camera3_capture_result_t result = {};
>> +	camera3_capture_result_t &result = descriptor->captureResult_;
>>   	result.num_output_buffers = request->num_output_buffers;
>>   	result.frame_number = request->frame_number;
>>   	result.partial_result = 0;
>> @@ -879,7 +880,7 @@ void CameraDevice::abortRequest(camera3_capture_request_t *request)
>>   	}
>>   	result.output_buffers = resultBuffers.data();
>>   
>> -	callbacks_->process_capture_result(callbacks_, &result);
>> +	descriptor->status_ = Camera3RequestDescriptor::Status::Error;
>>   }
>>   
>>   bool CameraDevice::isValidRequest(camera3_capture_request_t *camera3Request) const
>> @@ -1052,13 +1053,19 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
>>   		return ret;
>>   
>>   	/*
>> -	 * If flush is in progress abort the request. If the camera has been
>> -	 * stopped we have to re-start it to be able to process the request.
>> +	 * If flush is in progress abort the request and push the descriptor to
>> +	 * the queue. If the camera has been stopped we have to re-start it to
>> +	 * be able to process the request.
>>   	 */
>>   	MutexLocker stateLock(stateMutex_);
>>   
>>   	if (state_ == State::Flushing) {
>> -		abortRequest(camera3Request);
>> +		abortRequest(descriptors_.back().get(), camera3Request);
>> +		{
>> +			MutexLocker descriptorsLock(descriptorsMutex_);
>> +			descriptors_.push(std::move(descriptor));
>> +		}
>> +		sendCaptureResults();
>>   		return 0;
>>   	}
>>   
>> @@ -1116,7 +1123,7 @@ void CameraDevice::requestComplete(Request *request)
>>   	 * The buffer status is set to OK and later changed to ERROR if
>>   	 * post-processing/compression fails.
>>   	 */
>> -	camera3_capture_result_t captureResult = {};
>> +	camera3_capture_result_t &captureResult = descriptor->captureResult_;
>>   	captureResult.frame_number = descriptor->frameNumber_;
>>   	captureResult.num_output_buffers = descriptor->buffers_.size();
>>   	for (camera3_stream_buffer_t &buffer : descriptor->buffers_) {
>> @@ -1166,9 +1173,9 @@ void CameraDevice::requestComplete(Request *request)
>>   			buffer.status = CAMERA3_BUFFER_STATUS_ERROR;
>>   		}
>>   
>> -		callbacks_->process_capture_result(callbacks_, &captureResult);
>> +		descriptor->status_ = Camera3RequestDescriptor::Status::Error;
>> +		sendCaptureResults();
>>   
>> -		descriptors_.pop();
>>   		return;
>>   	}
>>   
>> @@ -1234,10 +1241,23 @@ void CameraDevice::requestComplete(Request *request)
>>   	}
>>   
>>   	captureResult.result = resultMetadata->get();
>> -	callbacks_->process_capture_result(callbacks_, &captureResult);
>> +	descriptor->status_ = Camera3RequestDescriptor::Status::Success;
>> +	sendCaptureResults();
>> +}
>>   
>> -	MutexLocker descriptorsLock(descriptorsMutex_);
>> -	descriptors_.pop();
>> +void CameraDevice::sendCaptureResults()
>> +{
>> +	MutexLocker lock(descriptorsMutex_);
>> +	while (!descriptors_.empty() && !descriptors_.front()->isPending()) {
>> +		std::unique_ptr<Camera3RequestDescriptor> descriptor =
>> +			std::move(descriptors_.front());
>> +		descriptors_.pop();
>> +
>> +		lock.unlock();
>> +		callbacks_->process_capture_result(callbacks_,
>> +						   &descriptor->captureResult_);
>> +		lock.lock();
>> +	}
>>   }
>>   
>>   std::string CameraDevice::logPrefix() const
>> diff --git a/src/android/camera_device.h b/src/android/camera_device.h
>> index 9ec510d5..dbfa7431 100644
>> --- a/src/android/camera_device.h
>> +++ b/src/android/camera_device.h
>> @@ -74,17 +74,28 @@ private:
>>   	CameraDevice(unsigned int id, std::shared_ptr<libcamera::Camera> camera);
>>   
>>   	struct Camera3RequestDescriptor {
>> +		enum class Status {
>> +			Pending,
>> +			Success,
>> +			Error,
>> +		};
>> +
>>   		Camera3RequestDescriptor() = default;
>>   		~Camera3RequestDescriptor() = default;
>>   		Camera3RequestDescriptor(libcamera::Camera *camera,
>>   					 const camera3_capture_request_t *camera3Request);
>>   		Camera3RequestDescriptor &operator=(Camera3RequestDescriptor &&) = default;
>>   
>> +		bool isPending() const { return status_ == Status::Pending; }
>> +
>>   		uint32_t frameNumber_ = 0;
>>   		std::vector<camera3_stream_buffer_t> buffers_;
>>   		std::vector<std::unique_ptr<libcamera::FrameBuffer>> frameBuffers_;
>>   		CameraMetadata settings_;
>>   		std::unique_ptr<CaptureRequest> request_;
>> +
>> +		camera3_capture_result_t captureResult_ = {};
>> +		Status status_ = Status::Pending;
>>   	};
>>   
>>   	enum class State {
>> @@ -99,12 +110,14 @@ private:
>>   	createFrameBuffer(const buffer_handle_t camera3buffer,
>>   			  libcamera::PixelFormat pixelFormat,
>>   			  const libcamera::Size &size);
>> -	void abortRequest(camera3_capture_request_t *request);
>> +	void abortRequest(Camera3RequestDescriptor *descriptor,
>> +			  camera3_capture_request_t *request);
>>   	bool isValidRequest(camera3_capture_request_t *request) const;
>>   	void notifyShutter(uint32_t frameNumber, uint64_t timestamp);
>>   	void notifyError(uint32_t frameNumber, camera3_stream_t *stream,
>>   			 camera3_error_msg_code code);
>>   	int processControls(Camera3RequestDescriptor *descriptor);
>> +	void sendCaptureResults();
>>   	std::unique_ptr<CameraMetadata> getResultMetadata(
>>   		const Camera3RequestDescriptor &descriptor) const;
>>