[libcamera-devel] [PATCH v5 3/4] android: post_processor: Make post processing async
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Oct 21 15:10:11 CEST 2021
Hi Umang,
On Thu, Oct 21, 2021 at 01:07:50PM +0530, Umang Jain wrote:
> On 10/20/21 4:12 PM, Umang Jain wrote:
> > Introduce a dedicated worker class derived from libcamera::Thread.
> > The worker class maintains a queue for post-processing requests
> > and waits for a post-processing request to become available.
> > It will process them as per FIFO before de-queuing it from the
> > queue.
> >
> > To get access to the source and destination buffers in the worker
> > thread, we also need to save a pointer to them in the
> > Camera3RequestDescriptor.
> >
> > This patch also implements a flush() for the PostProcessorWorker
> > class which is responsible to purge post-processing requests
> > queued up while a camera is stopping/flushing. It is hooked with
> > CameraStream::flush(), which isn't used currently but will be
> > used when we handle flush/stop scnearios in greater detail
> > subsequently (in a different patchset).
> >
> > The libcamera request completion handler CameraDevice::requestComplete()
> > assumes that the request that has just completed is at the front of the
> > queue. Now that the post-processor runs asynchronously, this isn't true
> > anymore, a request being post-processed will stay in the queue and a new
> > libcamera request may complete. Remove that assumption, and use the
> > request cookie to obtain the Camera3RequestDescriptor.
> >
> > Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > src/android/camera_device.cpp | 46 +++++----------
> > src/android/camera_request.h | 4 ++
> > src/android/camera_stream.cpp | 107 +++++++++++++++++++++++++++++++---
> > src/android/camera_stream.h | 38 +++++++++++-
> > 4 files changed, 156 insertions(+), 39 deletions(-)
> >
> > diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> > index 541c2c81..b14416ce 100644
> > --- a/src/android/camera_device.cpp
> > +++ b/src/android/camera_device.cpp
> > @@ -1020,29 +1020,8 @@ int CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reques
> >
> > void CameraDevice::requestComplete(Request *request)
> > {
> > - Camera3RequestDescriptor *descriptor;
> > - {
> > - MutexLocker descriptorsLock(descriptorsMutex_);
> > - ASSERT(!descriptors_.empty());
> > - descriptor = descriptors_.front().get();
> > - }
> > -
> > - if (descriptor->request_->cookie() != request->cookie()) {
> > - /*
> > - * \todo Clarify if the Camera has to be closed on
> > - * ERROR_DEVICE.
> > - */
> > - LOG(HAL, Error)
> > - << "Out-of-order completion for request "
> > - << utils::hex(request->cookie());
> > -
> > - MutexLocker descriptorsLock(descriptorsMutex_);
> > - descriptors_.pop();
> > -
> > - notifyError(0, nullptr, CAMERA3_MSG_ERROR_DEVICE);
> > -
> > - return;
> > - }
> > + Camera3RequestDescriptor *descriptor =
> > + reinterpret_cast<Camera3RequestDescriptor *>(request->cookie());
> >
> > /*
> > * Prepare the capture result for the Android camera stack.
> > @@ -1120,12 +1099,7 @@ void CameraDevice::requestComplete(Request *request)
> > bool needsPostProcessing = false;
> > Camera3RequestDescriptor::Status processingStatus =
> > Camera3RequestDescriptor::Status::Pending;
> > - /*
> > - * \todo Apply streamsProcessMutex_ when post-processing is adapted to run
> > - * asynchronously. If we introduce the streamsProcessMutex_ right away, the
> > - * lock will be held forever since it is synchronous at this point
> > - * (see streamProcessingComplete).
> > - */
> > +
> > for (auto &buffer : descriptor->buffers_) {
> > CameraStream *stream = buffer.stream;
> >
> > @@ -1145,7 +1119,13 @@ void CameraDevice::requestComplete(Request *request)
> > buffer.internalBuffer = src;
> >
> > needsPostProcessing = true;
> > - int ret = stream->process(*src, buffer, descriptor);
> > +
> > + int ret;
> > + {
> > + MutexLocker locker(descriptor->streamsProcessMutex_);
> > + ret = stream->process(*src, buffer, descriptor);
> > + }
> > +
> > if (ret) {
> > setBufferStatus(stream, buffer, descriptor,
> > Camera3RequestDescriptor::Status::Error);
> > @@ -1156,6 +1136,12 @@ void CameraDevice::requestComplete(Request *request)
> > if (needsPostProcessing) {
> > if (processingStatus == Camera3RequestDescriptor::Status::Error) {
> > descriptor->status_ = processingStatus;
> > + /*
> > + * \todo This is problematic when some streams are
> > + * queued successfully, but some fail to get queued.
> > + * We might end up with use-after-free situation for
> > + * descriptor in streamProcessingComplete().
> > + */
> > sendCaptureResults();
> > }
> >
> > diff --git a/src/android/camera_request.h b/src/android/camera_request.h
> > index 3a2774e0..85274414 100644
> > --- a/src/android/camera_request.h
> > +++ b/src/android/camera_request.h
> > @@ -18,6 +18,7 @@
> >
> > #include <hardware/camera3.h>
> >
> > +#include "camera_buffer.h"
> > #include "camera_metadata.h"
> > #include "camera_worker.h"
> >
> > @@ -39,6 +40,9 @@ public:
> > int fence;
> > Status status;
> > libcamera::FrameBuffer *internalBuffer = nullptr;
> > + std::unique_ptr<CameraBuffer> destBuffer;
> > + const libcamera::FrameBuffer *srcBuffer;
> > + Camera3RequestDescriptor *request = nullptr;
> > };
> >
> > Camera3RequestDescriptor(libcamera::Camera *camera,
> > diff --git a/src/android/camera_stream.cpp b/src/android/camera_stream.cpp
> > index b3cb06a2..a29ce33b 100644
> > --- a/src/android/camera_stream.cpp
> > +++ b/src/android/camera_stream.cpp
> > @@ -99,6 +99,7 @@ int CameraStream::configure()
> > if (ret)
> > return ret;
> >
> > + worker_ = std::make_unique<PostProcessorWorker>(postProcessor_.get());
> > postProcessor_->processComplete.connect(
> > this, [&](Camera3RequestDescriptor *request, PostProcessor::Status status) {
> > Camera3RequestDescriptor::Status bufferStatus =
> > @@ -110,6 +111,7 @@ int CameraStream::configure()
> > cameraDevice_->streamProcessingComplete(this, request,
> > bufferStatus);
> > });
> > + worker_->start();
> > }
> >
> > if (type_ == Type::Internal) {
> > @@ -179,23 +181,31 @@ int CameraStream::process(const FrameBuffer &source,
> > if (!postProcessor_)
> > return 0;
> >
> > - /*
> > - * \todo Buffer mapping and processing should be moved to a
> > - * separate thread.
> > - */
> > const StreamConfiguration &output = configuration();
> > - CameraBuffer destBuffer(*dest.camera3Buffer, output.pixelFormat,
> > - output.size, PROT_READ | PROT_WRITE);
> > - if (!destBuffer.isValid()) {
> > + dest.destBuffer = std::make_unique<CameraBuffer>(
> > + *dest.camera3Buffer, output.pixelFormat, output.size, PROT_READ | PROT_WRITE);
> > + if (!dest.destBuffer->isValid()) {
> > LOG(HAL, Error) << "Failed to create destination buffer";
> > return -EINVAL;
> > }
> >
> > - postProcessor_->process(source, &destBuffer, request);
> > + dest.srcBuffer = &source;
> > + dest.request = request;
> > +
> > + /* Push the postProcessor request to the worker queue. */
> > + worker_->queueRequest(&dest);
> >
> > return 0;
> > }
> >
> > +void CameraStream::flush()
> > +{
> > + if (!postProcessor_)
> > + return;
> > +
> > + worker_->flush();
> > +}
> > +
> > FrameBuffer *CameraStream::getBuffer()
> > {
> > if (!allocator_)
> > @@ -223,3 +233,84 @@ void CameraStream::putBuffer(FrameBuffer *buffer)
> >
> > buffers_.push_back(buffer);
> > }
> > +
> > +CameraStream::PostProcessorWorker::PostProcessorWorker(PostProcessor *postProcessor)
> > + : postProcessor_(postProcessor)
> > +{
> > +}
> > +
> > +CameraStream::PostProcessorWorker::~PostProcessorWorker()
> > +{
> > + {
> > + libcamera::MutexLocker lock(mutex_);
> > + state_ = State::Stopped;
> > + }
> > +
> > + cv_.notify_one();
> > + wait();
> > +}
> > +
> > +void CameraStream::PostProcessorWorker::start()
> > +{
> > + {
> > + libcamera::MutexLocker lock(mutex_);
> > + state_ = State::Running;
> > + }
> > +
> > + Thread::start();
> > +}
> > +
> > +void CameraStream::PostProcessorWorker::queueRequest(Camera3RequestDescriptor::StreamBuffer *dest)
> > +{
> > + {
> > + MutexLocker lock(mutex_);
> > + ASSERT(state_ == State::Running);
> > + requests_.push(dest);
> > + }
> > +
> > + cv_.notify_one();
> > +}
> > +
> > +void CameraStream::PostProcessorWorker::run()
> > +{
> > + MutexLocker locker(mutex_);
> > +
> > + while (1) {
> > + cv_.wait(locker, [&] {
> > + return state_ != State::Running || !requests_.empty();
> > + });
> > +
> > + if (state_ != State::Running)
> > + break;
> > +
> > + Camera3RequestDescriptor::StreamBuffer *stream = requests_.front();
> > + requests_.pop();
> > + locker.unlock();
> > +
> > + postProcessor_->process(*stream->srcBuffer, stream->destBuffer.get(),
> > + stream->request);
>
> As I have received in reviews, processComplete should emit a
> Camera3RequestDescriptor::StreamBuffer pointer, instead of having
> emitted currently a pointer to Camera3RequestDescriptor
>
> Now looking postProcessor_->process() call above, I think I should
> further migrate its signature to:
>
> PostProcessor::process(Camera3RequestDescriptor::StreamBuffer *stream)
>
> and all the three elements can be accessed from there.
>
> Laurent, do you agree with the design decision?
Yes, that looks good to me. Maybe the variable could also be renamed to
streamBuffer here, to avoid confusing it with a stream.
> > +
> > + locker.lock();
> > + }
> > +
> > + if (state_ == State::Flushing) {
> > + while (!requests_.empty()) {
> > + postProcessor_->processComplete.emit(
> > + requests_.front()->request,
> > + PostProcessor::Status::Error);
> > + requests_.pop();
> > + }
> > +
> > + state_ = State::Stopped;
> > + locker.unlock();
> > + }
> > +}
> > +
> > +void CameraStream::PostProcessorWorker::flush()
> > +{
> > + libcamera::MutexLocker lock(mutex_);
> > + state_ = State::Flushing;
> > + lock.unlock();
> > +
> > + cv_.notify_one();
> > +}
> > diff --git a/src/android/camera_stream.h b/src/android/camera_stream.h
> > index f242336e..64e32c77 100644
> > --- a/src/android/camera_stream.h
> > +++ b/src/android/camera_stream.h
> > @@ -7,12 +7,16 @@
> > #ifndef __ANDROID_CAMERA_STREAM_H__
> > #define __ANDROID_CAMERA_STREAM_H__
> >
> > +#include <condition_variable>
> > #include <memory>
> > #include <mutex>
> > +#include <queue>
> > #include <vector>
> >
> > #include <hardware/camera3.h>
> >
> > +#include <libcamera/base/thread.h>
> > +
> > #include <libcamera/camera.h>
> > #include <libcamera/framebuffer.h>
> > #include <libcamera/framebuffer_allocator.h>
> > @@ -20,9 +24,9 @@
> > #include <libcamera/pixel_format.h>
> >
> > #include "camera_request.h"
> > +#include "post_processor.h"
> >
> > class CameraDevice;
> > -class PostProcessor;
> >
> > class CameraStream
> > {
> > @@ -126,8 +130,38 @@ public:
> > Camera3RequestDescriptor *request);
> > libcamera::FrameBuffer *getBuffer();
> > void putBuffer(libcamera::FrameBuffer *buffer);
> > + void flush();
> >
> > private:
> > + class PostProcessorWorker : public libcamera::Thread
> > + {
> > + public:
> > + enum class State {
> > + Stopped,
> > + Running,
> > + Flushing,
> > + };
> > +
> > + PostProcessorWorker(PostProcessor *postProcessor);
> > + ~PostProcessorWorker();
> > +
> > + void start();
> > + void queueRequest(Camera3RequestDescriptor::StreamBuffer *request);
> > + void flush();
> > +
> > + protected:
> > + void run() override;
> > +
> > + private:
> > + PostProcessor *postProcessor_;
> > +
> > + libcamera::Mutex mutex_;
> > + std::condition_variable cv_;
> > +
> > + std::queue<Camera3RequestDescriptor::StreamBuffer *> requests_;
> > + State state_;
> > + };
> > +
> > int waitFence(int fence);
> >
> > CameraDevice *const cameraDevice_;
> > @@ -144,6 +178,8 @@ private:
> > */
> > std::unique_ptr<std::mutex> mutex_;
> > std::unique_ptr<PostProcessor> postProcessor_;
> > +
> > + std::unique_ptr<PostProcessorWorker> worker_;
> > };
> >
> > #endif /* __ANDROID_CAMERA_STREAM__ */
--
Regards,
Laurent Pinchart
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