[libcamera-devel] [PATCH v4 4/4] android: camera_device: Send capture results by inspecting the queue
Umang Jain
umang.jain at ideasonboard.com
Thu Sep 30 07:13:58 CEST 2021
Hi Jacopo
On 9/30/21 12:20 AM, Jacopo Mondi wrote:
> Hi Umang,
>
> On Wed, Sep 29, 2021 at 07:00:30PM +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
> ready to be sent
>
>> or needs to be waited upon. This ensures that the order of completion is
>> respected for the requests.
>>
>> Since we are fixing out-of-order request completion in abortRequest(),
>> change the function to read from the Camera3RequestDescriptor directly,
>> instead of camera3_capture_request_t. The descriptor should have all the
>> information necessary to set the request buffers' state to error.
>>
>> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
>> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> Reviewed-by: Hirokazu Honda <hiroh at chromium.org>
>> ---
>> src/android/camera_device.cpp | 59 ++++++++++++++++++++++++-----------
>> src/android/camera_device.h | 14 ++++++++-
>> 2 files changed, 54 insertions(+), 19 deletions(-)
>>
>> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
>> index 45350563..38c64bb7 100644
>> --- a/src/android/camera_device.cpp
>> +++ b/src/android/camera_device.cpp
>> @@ -860,25 +860,25 @@ int CameraDevice::processControls(Camera3RequestDescriptor *descriptor)
>> return 0;
>> }
>>
>> -void CameraDevice::abortRequest(camera3_capture_request_t *request) const
>> +void CameraDevice::abortRequest(Camera3RequestDescriptor *descriptor) const
>> {
>> - notifyError(request->frame_number, nullptr, CAMERA3_MSG_ERROR_REQUEST);
>> + notifyError(descriptor->frameNumber_, nullptr, CAMERA3_MSG_ERROR_REQUEST);
>>
>> - camera3_capture_result_t result = {};
>> - result.num_output_buffers = request->num_output_buffers;
>> - result.frame_number = request->frame_number;
>> + camera3_capture_result_t &result = descriptor->captureResult_;
>> + result.num_output_buffers = descriptor->buffers_.size();
>> + result.frame_number = descriptor->frameNumber_;
>> result.partial_result = 0;
>>
>> std::vector<camera3_stream_buffer_t> resultBuffers(result.num_output_buffers);
>> for (auto [i, buffer] : utils::enumerate(resultBuffers)) {
>> - buffer = request->output_buffers[i];
>> - buffer.release_fence = request->output_buffers[i].acquire_fence;
>> + buffer = descriptor->buffers_[i];
>> + buffer.release_fence = descriptor->buffers_[i].acquire_fence;
>> buffer.acquire_fence = -1;
>> buffer.status = CAMERA3_BUFFER_STATUS_ERROR;
>> }
>> 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
>> @@ -1050,13 +1050,21 @@ 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 set the request status to error and place it
>> + * on the queue to be later completed. 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(descriptor.get());
>> + {
>> + MutexLocker descriptorsLock(descriptorsMutex_);
>> + descriptors_.push(std::move(descriptor));
>> + }
>> +
>> + sendCaptureResults();
>> +
>> return 0;
>> }
>>
>> @@ -1116,7 +1124,7 @@ 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_) {
>> @@ -1166,10 +1174,9 @@ void CameraDevice::requestComplete(Request *request)
>> buffer.status = CAMERA3_BUFFER_STATUS_ERROR;
>> }
>>
>> - callbacks_->process_capture_result(callbacks_, &captureResult);
>> + descriptor->status_ = Camera3RequestDescriptor::Status::Error;
>> + sendCaptureResults();
>>
>> - MutexLocker descriptorsLock(descriptorsMutex_);
>> - descriptors_.pop();
>> return;
>> }
>>
>> @@ -1235,10 +1242,26 @@ 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()) {
>> + auto descriptor = std::move(descriptors_.front());
>> + descriptors_.pop();
>> +
>> + /*
>> + * \todo Measure performance impact of grain locking here against
>> + * coarse locking.
> I find this a bit hard to parse. Maybe
>
> * \todo Releasing and re-acquiring the critical
> * section for every request completion might have an
> * impact on performaces which should be measured.
s/performaces/performance/
I have updated to:
* \todo Releasing and re-acquiring the critical section for
* every request completion (grain-locking) might have an
* impact on performance which should be measured.
>
> Up to you, really.
>
> All minors might be optionally fixed when applying
>
> Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
Thanks!
>
>> + */
>> + 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 85497921..b7d774fe 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 +110,13 @@ private:
>> createFrameBuffer(const buffer_handle_t camera3buffer,
>> libcamera::PixelFormat pixelFormat,
>> const libcamera::Size &size);
>> - void abortRequest(camera3_capture_request_t *request) const;
>> + void abortRequest(Camera3RequestDescriptor *descriptor) const;
>> 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) const;
>> int processControls(Camera3RequestDescriptor *descriptor);
>> + void sendCaptureResults();
>> std::unique_ptr<CameraMetadata> getResultMetadata(
>> const Camera3RequestDescriptor &descriptor) const;
>>
>> --
>> 2.31.0
>>
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