[libcamera-devel] [PATCH v3 02/10] android: camera_device: Transform descriptors_ map to queue
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Wed Sep 22 00:16:59 CEST 2021
Hi Umang,
On Tue, Sep 21, 2021 at 09:56:22AM +0530, Umang Jain wrote:
> On 9/21/21 12:36 AM, Laurent Pinchart wrote:
> > On Mon, Sep 20, 2021 at 11:07:44PM +0530, Umang Jain wrote:
> >> The descriptors_ map hold Camera3RequestDescriptor(s) which are
> >> per-capture request placed by the framework to libcamera HAL.
> >> CameraDevice::requestComplete() looks for the descriptor for which the
> >> camera request has been completed and removes it from the map.
> >> However, this approach has its limitations going forwards.
> >>
> >> In subsequent commits, the post-processing operation which happens
> >> in requestComplete() synchronously, is going to be run asynchronously.
> >> Therefore, instead of a map for descriptors, a queue makes more sense
> >> going forwards and the framework expects capture results to be received
> >> in the same order as they were queued. When the async processing is
> >> completed, the descriptor queue is inspected to send back the capture
> >> results and then de-queued. This helps to maintain the order of sending
> >> back the capture results whilst preventing unnecessary complexity of
> >> using a map.
> >>
> >> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> >> ---
> >> src/android/camera_device.cpp | 89 ++++++++++++++++++-----------------
> >> src/android/camera_device.h | 5 +-
> >> 2 files changed, 48 insertions(+), 46 deletions(-)
> >>
> >> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> >> index f461e14c..0562c225 100644
> >> --- a/src/android/camera_device.cpp
> >> +++ b/src/android/camera_device.cpp
> >> @@ -926,7 +926,9 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >> * The descriptor and the associated memory reserved here are freed
> >> * at request complete time.
> >> */
> >> - Camera3RequestDescriptor descriptor(camera_.get(), camera3Request);
> >> + std::unique_ptr<Camera3RequestDescriptor> descriptor =
> >> + std::make_unique<Camera3RequestDescriptor>(camera_.get(),
> >> + camera3Request);
> >>
> >> /*
> >> * \todo The Android request model is incremental, settings passed in
> >> @@ -937,12 +939,12 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >> if (camera3Request->settings)
> >> lastSettings_ = camera3Request->settings;
> >> else
> >> - descriptor.settings_ = lastSettings_;
> >> + descriptor->settings_ = lastSettings_;
> >>
> >> - LOG(HAL, Debug) << "Queueing request " << descriptor.request_->cookie()
> >> - << " with " << descriptor.buffers_.size() << " streams";
> >> - for (unsigned int i = 0; i < descriptor.buffers_.size(); ++i) {
> >> - const camera3_stream_buffer_t &camera3Buffer = descriptor.buffers_[i];
> >> + LOG(HAL, Debug) << "Queueing request " << descriptor->request_->cookie()
> >> + << " with " << descriptor->buffers_.size() << " streams";
> >> + for (unsigned int i = 0; i < descriptor->buffers_.size(); ++i) {
> >> + const camera3_stream_buffer_t &camera3Buffer = descriptor->buffers_[i];
> >> camera3_stream *camera3Stream = camera3Buffer.stream;
> >> CameraStream *cameraStream = static_cast<CameraStream *>(camera3Stream->priv);
> >>
> >> @@ -977,7 +979,7 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >> buffer = createFrameBuffer(*camera3Buffer.buffer,
> >> cameraStream->configuration().pixelFormat,
> >> cameraStream->configuration().size);
> >> - descriptor.frameBuffers_.emplace_back(buffer);
> >> + descriptor->frameBuffers_.emplace_back(buffer);
> >> LOG(HAL, Debug) << ss.str() << " (direct)";
> >> break;
> >>
> >> @@ -999,7 +1001,7 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >> return -ENOMEM;
> >> }
> >>
> >> - descriptor.request_->addBuffer(cameraStream->stream(), buffer,
> >> + descriptor->request_->addBuffer(cameraStream->stream(), buffer,
> >> camera3Buffer.acquire_fence);
> >> }
> >>
> >> @@ -1007,7 +1009,7 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >> * Translate controls from Android to libcamera and queue the request
> >> * to the CameraWorker thread.
> >> */
> >> - int ret = processControls(&descriptor);
> >> + int ret = processControls(descriptor.get());
> >> if (ret)
> >> return ret;
> >>
> >> @@ -1035,11 +1037,11 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >> state_ = State::Running;
> >> }
> >>
> >> - worker_.queueRequest(descriptor.request_.get());
> >> + worker_.queueRequest(descriptor->request_.get());
> >>
> >> {
> >> MutexLocker descriptorsLock(descriptorsMutex_);
> >> - descriptors_[descriptor.request_->cookie()] = std::move(descriptor);
> >> + descriptors_.push_back(std::move(descriptor));
> >> }
> >
> > We have a race condition here, worker_.queueRequest() should go after
> > adding the request to the queue. Could you fix it in a patch on top ?
>
> Do you mean the race condition is existing already, with the
> descriptors_ map (that has been removed from this patch)?
Correct, it's already here.
> Yes, I can introduce a patch before this one, that fixes the race first
> in the map itself. Is my understanding correct?
Sounds good to me. It should be a small patch.
> >>
> >> return 0;
> >> @@ -1047,26 +1049,22 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >>
> >> void CameraDevice::requestComplete(Request *request)
> >> {
> >> - decltype(descriptors_)::node_type node;
> >> - {
> >> - MutexLocker descriptorsLock(descriptorsMutex_);
> >> - auto it = descriptors_.find(request->cookie());
> >> - if (it == descriptors_.end()) {
> >> - /*
> >> - * \todo Clarify if the Camera has to be closed on
> >> - * ERROR_DEVICE and possibly demote the Fatal to simple
> >> - * Error.
> >> - */
> >> - notifyError(0, nullptr, CAMERA3_MSG_ERROR_DEVICE);
> >> - LOG(HAL, Fatal)
> >> - << "Unknown request: " << request->cookie();
> >> + if (descriptors_.empty())
> >> + return;
> >>
> >> - return;
> >> - }
> >> + Camera3RequestDescriptor *descriptor = descriptors_.front().get();
> >
> > This needs to be protected by descriptorsMutex_.
> >
> > Camera3RequestDescriptor *descriptor;
> >
> > {
> > MutexLocker descriptorsLock(descriptorsMutex_);
> > descriptor = descriptors_.front().get();
> > }
> >
> >> + if (descriptor->request_->cookie() != request->cookie()) {
> >
> > This is correct as long as we handle post-processing synchronously.
> > Let's see how it evolves in subsequent patches.
>
> Why not valid for async post-processing?
>
> So this is requestComplete() function, invoked whenever a
> libcamera::Request is completed by libcamera::Camera. The completion is
> guaranteed to be done in order, right ? Later in this function, the
> post-processing shall happen (sync or async).
When we'll move to async post-processing, the request at the front of
the queue will be a request undergoing post-processing. libcamera may
signal completion of the next request before the post-processing is
complete, so the check will fail.
> >> + /*
> >> + * \todo Clarify if the Camera has to be closed on
> >> + * ERROR_DEVICE and possibly demote the Fatal to simple
> >> + * Error.
> >> + */
> >> + notifyError(0, nullptr, CAMERA3_MSG_ERROR_DEVICE);
> >> + LOG(HAL, Fatal)
> >> + << "Unknown request: " << request->cookie();
> >
> > I'd change the message to
> >
> > << "Out-of-order completion for request "
> > << request->cookie();
> >
> > By the way, with the cookie containing a pointer, I think it would be
> > more readable in hex. Maybe a patch on top to use utils::hex() ?
>
> Makes sense, I'll double check
>
> >>
> >> - node = descriptors_.extract(it);
> >> + return;
> >> }
> >> - Camera3RequestDescriptor &descriptor = node.mapped();
> >>
> >> /*
> >> * Prepare the capture result for the Android camera stack.
> >> @@ -1075,14 +1073,14 @@ void CameraDevice::requestComplete(Request *request)
> >> * post-processing/compression fails.
> >> */
> >> camera3_capture_result_t captureResult = {};
> >> - captureResult.frame_number = descriptor.frameNumber_;
> >> - captureResult.num_output_buffers = descriptor.buffers_.size();
> >> - for (camera3_stream_buffer_t &buffer : descriptor.buffers_) {
> >> + captureResult.frame_number = descriptor->frameNumber_;
> >> + captureResult.num_output_buffers = descriptor->buffers_.size();
> >> + for (camera3_stream_buffer_t &buffer : descriptor->buffers_) {
> >> buffer.acquire_fence = -1;
> >> buffer.release_fence = -1;
> >> buffer.status = CAMERA3_BUFFER_STATUS_OK;
> >> }
> >> - captureResult.output_buffers = descriptor.buffers_.data();
> >> + captureResult.output_buffers = descriptor->buffers_.data();
> >> captureResult.partial_result = 1;
> >>
> >> /*
> >> @@ -1094,14 +1092,15 @@ void CameraDevice::requestComplete(Request *request)
> >> << " not successfully completed: "
> >> << request->status();
> >>
> >> - notifyError(descriptor.frameNumber_, nullptr,
> >> + notifyError(descriptor->frameNumber_, nullptr,
> >> CAMERA3_MSG_ERROR_REQUEST);
> >>
> >> captureResult.partial_result = 0;
> >> - for (camera3_stream_buffer_t &buffer : descriptor.buffers_)
> >> + for (camera3_stream_buffer_t &buffer : descriptor->buffers_)
> >> buffer.status = CAMERA3_BUFFER_STATUS_ERROR;
> >> callbacks_->process_capture_result(callbacks_, &captureResult);
> >>
> >> + descriptors_.pop_front();
> >
> > I'm slightly concerned that in some paths we could complete the request
> > but forget to remove it from the queue. Maybe wrapping
> > callbacks_->process_capture_result() and descriptors_.pop_front() in a
> > function would be good. Let's see how it looks like with the whole
> > series applied.
>
> This is a good point and has been address already via
> sendCaptureResults() in subsequent patches.
>
> However, this particular error path you have pointed out here, is the
> /only/ part where queue.front() is dropped, other than ofcoourse in
> sendCaptureResults(). hmm, I'll take a look if I can figure it out too
> and have a singular place of processsing the queue.
>
> >> return;
> >> }
> >>
> >> @@ -1113,10 +1112,10 @@ void CameraDevice::requestComplete(Request *request)
> >> */
> >> uint64_t sensorTimestamp = static_cast<uint64_t>(request->metadata()
> >> .get(controls::SensorTimestamp));
> >> - notifyShutter(descriptor.frameNumber_, sensorTimestamp);
> >> + notifyShutter(descriptor->frameNumber_, sensorTimestamp);
> >>
> >> LOG(HAL, Debug) << "Request " << request->cookie() << " completed with "
> >> - << descriptor.buffers_.size() << " streams";
> >> + << descriptor->buffers_.size() << " streams";
> >>
> >> /*
> >> * Generate the metadata associated with the captured buffers.
> >> @@ -1126,14 +1125,14 @@ void CameraDevice::requestComplete(Request *request)
> >> */
> >> std::unique_ptr<CameraMetadata> resultMetadata = getResultMetadata(descriptor);
> >> if (!resultMetadata) {
> >> - notifyError(descriptor.frameNumber_, nullptr, CAMERA3_MSG_ERROR_RESULT);
> >> + notifyError(descriptor->frameNumber_, nullptr, CAMERA3_MSG_ERROR_RESULT);
> >>
> >> /* The camera framework expects an empty metadata pack on error. */
> >> resultMetadata = std::make_unique<CameraMetadata>(0, 0);
> >> }
> >>
> >> /* Handle any JPEG compression. */
> >> - for (camera3_stream_buffer_t &buffer : descriptor.buffers_) {
> >> + for (camera3_stream_buffer_t &buffer : descriptor->buffers_) {
> >> CameraStream *cameraStream =
> >> static_cast<CameraStream *>(buffer.stream->priv);
> >>
> >> @@ -1144,13 +1143,13 @@ void CameraDevice::requestComplete(Request *request)
> >> if (!src) {
> >> LOG(HAL, Error) << "Failed to find a source stream buffer";
> >> buffer.status = CAMERA3_BUFFER_STATUS_ERROR;
> >> - notifyError(descriptor.frameNumber_, buffer.stream,
> >> + notifyError(descriptor->frameNumber_, buffer.stream,
> >> CAMERA3_MSG_ERROR_BUFFER);
> >> continue;
> >> }
> >>
> >> int ret = cameraStream->process(*src, *buffer.buffer,
> >> - descriptor.settings_,
> >> + descriptor->settings_,
> >> resultMetadata.get());
> >> /*
> >> * Return the FrameBuffer to the CameraStream now that we're
> >> @@ -1161,13 +1160,15 @@ void CameraDevice::requestComplete(Request *request)
> >>
> >> if (ret) {
> >> buffer.status = CAMERA3_BUFFER_STATUS_ERROR;
> >> - notifyError(descriptor.frameNumber_, buffer.stream,
> >> + notifyError(descriptor->frameNumber_, buffer.stream,
> >> CAMERA3_MSG_ERROR_BUFFER);
> >> }
> >> }
> >>
> >> captureResult.result = resultMetadata->get();
> >> callbacks_->process_capture_result(callbacks_, &captureResult);
> >> +
> >> + descriptors_.pop_front();
> >> }
> >>
> >> std::string CameraDevice::logPrefix() const
> >> @@ -1203,10 +1204,10 @@ void CameraDevice::notifyError(uint32_t frameNumber, camera3_stream_t *stream,
> >> * Produce a set of fixed result metadata.
> >> */
> >> std::unique_ptr<CameraMetadata>
> >> -CameraDevice::getResultMetadata(const Camera3RequestDescriptor &descriptor) const
> >> +CameraDevice::getResultMetadata(const Camera3RequestDescriptor *descriptor) const
> >> {
> >> - const ControlList &metadata = descriptor.request_->metadata();
> >> - const CameraMetadata &settings = descriptor.settings_;
> >> + const ControlList &metadata = descriptor->request_->metadata();
> >> + const CameraMetadata &settings = descriptor->settings_;
> >> camera_metadata_ro_entry_t entry;
> >> bool found;
> >>
> >> diff --git a/src/android/camera_device.h b/src/android/camera_device.h
> >> index a5576927..9c895b25 100644
> >> --- a/src/android/camera_device.h
> >> +++ b/src/android/camera_device.h
> >> @@ -7,6 +7,7 @@
> >> #ifndef __ANDROID_CAMERA_DEVICE_H__
> >> #define __ANDROID_CAMERA_DEVICE_H__
> >>
> >> +#include <deque>
> >> #include <map>
> >> #include <memory>
> >> #include <mutex>
> >> @@ -103,7 +104,7 @@ private:
> >> camera3_error_msg_code code);
> >> int processControls(Camera3RequestDescriptor *descriptor);
> >> std::unique_ptr<CameraMetadata> getResultMetadata(
> >> - const Camera3RequestDescriptor &descriptor) const;
> >> + const Camera3RequestDescriptor *descriptor) const;
> >>
> >> unsigned int id_;
> >> camera3_device_t camera3Device_;
> >> @@ -123,7 +124,7 @@ private:
> >> std::vector<CameraStream> streams_;
> >>
> >> libcamera::Mutex descriptorsMutex_; /* Protects descriptors_. */
> >> - std::map<uint64_t, Camera3RequestDescriptor> descriptors_;
> >> + std::deque<std::unique_ptr<Camera3RequestDescriptor>> descriptors_;
> >
> > Could we use a std::queue instead ? It will be implemented on top of a
> > std::deque, so there will be no change in performances, but it gives us
> > the semantics we need (essentially, a FIFO).
>
> Yes, great! The deque is coming from earlier version where we need to
> iterate over the queue.
>
> I see, no place as such in v3, where the queue is iterated upon, so we
> can surely use std::queue.
>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> >
> >> std::string maker_;
> >> std::string model_;
--
Regards,
Laurent Pinchart
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