[libcamera-devel] [PATCH v7 7/7] android: post_processor: Make post processing async
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Tue Oct 26 00:05:13 CEST 2021
Hi Umang,
Thank you for the patch.
On Tue, Oct 26, 2021 at 02:08:33AM +0530, 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.
>
> The entire post-processing handling iteration is locked under
> streamProcessMutex_ which helps us to queue all the post-processing
s/streamProcessMutex_/streamsProcessMutex_/
> request at once, before any of the post-processing completion slot
> (streamProcessingComplete()) is allowed to run for post-processing
> requests completing in parallel. This helps us to manage both
> synchronous and asynchronous errors encountered during the entire
> post processing operation. Since a post-processing operation can
> even complete after CameraDevice::requestComplete() has returned,
> we need to check and complete the descriptor from
> streamProcessingComplete() running in the PostProcessorWorker's
> thread.
>
> 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 scenarios 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 | 44 ++++++---------
> src/android/camera_stream.cpp | 101 ++++++++++++++++++++++++++++++++--
> src/android/camera_stream.h | 37 +++++++++++++
> 3 files changed, 151 insertions(+), 31 deletions(-)
>
> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> index 3ded0f7e..53ebe0ea 100644
> --- a/src/android/camera_device.cpp
> +++ b/src/android/camera_device.cpp
> @@ -1027,29 +1027,8 @@ 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.
> @@ -1124,9 +1103,13 @@ void CameraDevice::requestComplete(Request *request)
> }
>
> /* Handle post-processing. */
> + MutexLocker locker(descriptor->streamsProcessMutex_);
> +
> /*
> - * \todo Protect the loop below with streamProcessMutex_ when post
In the patch that introduced this,
s/streamProcessMutex_/streamsProcessMutex_/
> - * processor runs asynchronously.
> + * Queue all the post-processing streams request at once. The completion
> + * slot streamProcessingComplete() can only execute when we are out
> + * this critical section. This helps to handle synchronous errors here
> + * itself.
> */
> auto iter = descriptor->pendingStreamsToProcess_.begin();
> while (iter != descriptor->pendingStreamsToProcess_.end()) {
> @@ -1158,8 +1141,10 @@ void CameraDevice::requestComplete(Request *request)
> }
> }
>
> - if (descriptor->pendingStreamsToProcess_.empty())
> + if (descriptor->pendingStreamsToProcess_.empty()) {
> + locker.unlock();
> completeDescriptor(descriptor);
> + }
> }
>
> void CameraDevice::completeDescriptor(Camera3RequestDescriptor *descriptor)
> @@ -1245,6 +1230,13 @@ void CameraDevice::streamProcessingComplete(Camera3RequestDescriptor::StreamBuff
> MutexLocker locker(request->streamsProcessMutex_);
>
> request->pendingStreamsToProcess_.erase(streamBuffer->stream);
> +
> + if (!request->pendingStreamsToProcess_.empty())
> + return;
> +
> + locker.unlock();
Maybe
{
MutexLocker locker(request->streamsProcessMutex_);
request->pendingStreamsToProcess_.erase(streamBuffer->stream);
if (!request->pendingStreamsToProcess_.empty())
return;
}
up to you.
> +
> + completeDescriptor(streamBuffer->request);
> }
>
> std::string CameraDevice::logPrefix() const
> diff --git a/src/android/camera_stream.cpp b/src/android/camera_stream.cpp
> index fed99022..9023c13c 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::StreamBuffer *streamBuffer,
> PostProcessor::Status status) {
> @@ -112,6 +113,8 @@ int CameraStream::configure()
> cameraDevice_->streamProcessingComplete(streamBuffer,
> bufferStatus);
> });
> +
> + worker_->start();
> }
>
> if (type_ == Type::Internal) {
> @@ -178,10 +181,6 @@ int CameraStream::process(Camera3RequestDescriptor::StreamBuffer *streamBuffer)
> streamBuffer->fence = -1;
> }
>
> - /*
> - * \todo Buffer mapping and processing should be moved to a
> - * separate thread.
> - */
> const StreamConfiguration &output = configuration();
> streamBuffer->dstBuffer = std::make_unique<CameraBuffer>(
> *streamBuffer->camera3Buffer, output.pixelFormat, output.size,
> @@ -191,11 +190,19 @@ int CameraStream::process(Camera3RequestDescriptor::StreamBuffer *streamBuffer)
> return -EINVAL;
> }
>
> - postProcessor_->process(streamBuffer);
> + worker_->queueRequest(streamBuffer);
>
> return 0;
> }
>
> +void CameraStream::flush()
> +{
> + if (!postProcessor_)
> + return;
> +
> + worker_->flush();
> +}
> +
> FrameBuffer *CameraStream::getBuffer()
> {
> if (!allocator_)
> @@ -223,3 +230,87 @@ 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_);
> + ASSERT(state_ != State::Running);
> + 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 *streamBuffer = requests_.front();
> + requests_.pop();
> + locker.unlock();
> +
> + postProcessor_->process(streamBuffer);
> +
> + locker.lock();
> + }
> +
> + if (state_ == State::Flushing) {
> + std::queue<Camera3RequestDescriptor::StreamBuffer *> requests =
> + std::move(requests_);
> + locker.unlock();
> +
> + while (!requests.empty()) {
> + postProcessor_->processComplete.emit(
> + requests.front(), PostProcessor::Status::Error);
> + requests.pop();
> + }
> +
> + locker.lock();
> + state_ = State::Stopped;
> + }
> +}
> +
> +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 e74a9a3b..1588938a 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>
> @@ -20,6 +24,7 @@
> #include <libcamera/pixel_format.h>
>
> #include "camera_request.h"
> +#include "post_processor.h"
>
> class CameraDevice;
> class PostProcessor;
You can drop the forward declaration.
> @@ -124,8 +129,38 @@ public:
> int process(Camera3RequestDescriptor::StreamBuffer *streamBuffer);
> 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_ = State::Stopped;
> + };
> +
> int waitFence(int fence);
>
> CameraDevice *const cameraDevice_;
> @@ -142,6 +177,8 @@ 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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