[libcamera-devel] [PATCH v3 05/17] py: Create PyCameraManager
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Aug 18 21:18:18 CEST 2022
Hi Tomi
On Thu, Aug 18, 2022 at 04:22:30PM +0200, Jacopo Mondi wrote:
> On Fri, Jul 01, 2022 at 11:45:09AM +0300, Tomi Valkeinen wrote:
> > Wrap the CameraManager with a PyCameraManager class and move the related
> > code inside the new class.
> >
> > This helps understanding the life times of the used-to-be global
> > variables, gets rid of static handleRequestCompleted function, and
> > allows us to simplify the binding code as the more complex pieces are
> > inside the class.
> >
> > There should be no user visible functional changes.
> >
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
With Jacopo's comments addressed (except for the ones that got resolved
in the replies to your patch),
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > src/py/libcamera/meson.build | 1 +
> > src/py/libcamera/py_camera_manager.cpp | 125 +++++++++++++++++++++++++
> > src/py/libcamera/py_camera_manager.h | 44 +++++++++
> > src/py/libcamera/py_main.cpp | 117 +++++------------------
> > 4 files changed, 193 insertions(+), 94 deletions(-)
> > create mode 100644 src/py/libcamera/py_camera_manager.cpp
> > create mode 100644 src/py/libcamera/py_camera_manager.h
> >
> > diff --git a/src/py/libcamera/meson.build b/src/py/libcamera/meson.build
> > index 04578bac..ad2a6858 100644
> > --- a/src/py/libcamera/meson.build
> > +++ b/src/py/libcamera/meson.build
> > @@ -13,6 +13,7 @@ pybind11_proj = subproject('pybind11')
> > pybind11_dep = pybind11_proj.get_variable('pybind11_dep')
> >
> > pycamera_sources = files([
> > + 'py_camera_manager.cpp',
> > 'py_enums.cpp',
> > 'py_geometry.cpp',
> > 'py_helpers.cpp',
> > diff --git a/src/py/libcamera/py_camera_manager.cpp b/src/py/libcamera/py_camera_manager.cpp
> > new file mode 100644
> > index 00000000..ad47271d
> > --- /dev/null
> > +++ b/src/py/libcamera/py_camera_manager.cpp
> > @@ -0,0 +1,125 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
> > + */
> > +
> > +#include "py_camera_manager.h"
> > +
> > +#include <errno.h>
> > +#include <sys/eventfd.h>
> > +#include <system_error>
> > +#include <unistd.h>
> > +
> > +#include "py_main.h"
> > +
> > +namespace py = pybind11;
> > +
> > +using namespace libcamera;
> > +
> > +PyCameraManager::PyCameraManager()
> > +{
> > + LOG(Python, Debug) << "PyCameraManager()";
>
> Don't you need to LOG_DECLARE_CATEGORY() ?
>
> > +
> > + cameraManager_ = std::make_unique<CameraManager>();
> > +
> > + int fd = eventfd(0, 0);
> > + if (fd == -1)
> > + throw std::system_error(errno, std::generic_category(),
> > + "Failed to create eventfd");
> > +
> > + eventFd_ = fd;
>
> You can use UniqueFD() to avoid manually handling the eventfd file
> descriptor
>
> > +
> > + int ret = cameraManager_->start();
> > + if (ret) {
> > + close(fd);
> > + eventFd_ = -1;
> > + throw std::system_error(-ret, std::generic_category(),
> > + "Failed to start CameraManager");
> > + }
> > +}
> > +
> > +PyCameraManager::~PyCameraManager()
> > +{
> > + LOG(Python, Debug) << "~PyCameraManager()";
> > +
> > + if (eventFd_ != -1) {
> > + close(eventFd_);
> > + eventFd_ = -1;
> > + }
> > +}
> > +
> > +py::list PyCameraManager::cameras()
> > +{
> > + /*
> > + * Create a list of Cameras, where each camera has a keep-alive to
> > + * CameraManager.
> > + */
> > + py::list l;
> > +
> > + for (auto &camera : cameraManager_->cameras()) {
> > + py::object py_cm = py::cast(this);
> > + py::object py_cam = py::cast(camera);
> > + py::detail::keep_alive_impl(py_cam, py_cm);
> > + l.append(py_cam);
> > + }
> > +
> > + return l;
>
> I was about to suggest creating the list at creation time and cache
> it. But indeed cameras can be added or removed from the system
>
> > +}
> > +
> > +std::vector<py::object> PyCameraManager::getReadyRequests()
> > +{
> > + readFd();
> > +
> > + std::vector<py::object> ret;
> > +
> > + for (Request *request : getCompletedRequests()) {
> > + py::object o = py::cast(request);
> > + /* Decrease the ref increased in Camera.queue_request() */
> > + o.dec_ref();
> > + ret.push_back(o);
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +/* Note: Called from another thread */
> > +void PyCameraManager::handleRequestCompleted(Request *req)
> > +{
> > + pushRequest(req);
>
> Is this function only used here ?
> Should it be inlined ?
>
> > + writeFd();
> > +}
> > +
> > +void PyCameraManager::writeFd()
> > +{
> > + uint64_t v = 1;
> > +
> > + size_t s = write(eventFd_, &v, 8);
>
> Any reason to write an 8 byte uint64 ?
> Just curious
>
> > + /*
> > + * We should never fail, and have no simple means to manage the error,
> > + * so let's log a fatal error.
> > + */
> > + if (s != 8)
> > + LOG(Python, Fatal) << "Unable to write to eventfd";
> > +}
> > +
> > +void PyCameraManager::readFd()
> > +{
> > + uint8_t buf[8];
> > +
> > + if (read(eventFd_, buf, 8) != 8)
> > + throw std::system_error(errno, std::generic_category());
> > +}
> > +
> > +void PyCameraManager::pushRequest(Request *req)
> > +{
> > + std::lock_guard guard(completedRequestsMutex_);
> > + completedRequests_.push_back(req);
> > +}
> > +
> > +std::vector<Request *> PyCameraManager::getCompletedRequests()
> > +{
> > + std::vector<Request *> v;
> > + std::lock_guard guard(completedRequestsMutex_);
> > + swap(v, completedRequests_);
> > + return v;
> > +}
> > diff --git a/src/py/libcamera/py_camera_manager.h b/src/py/libcamera/py_camera_manager.h
> > new file mode 100644
> > index 00000000..9c15f814
> > --- /dev/null
> > +++ b/src/py/libcamera/py_camera_manager.h
> > @@ -0,0 +1,44 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
> > + */
> > +
> > +#pragma once
> > +
> > +#include <mutex>
> > +
> > +#include <libcamera/libcamera.h>
> > +
> > +#include <pybind11/smart_holder.h>
> > +
> > +using namespace libcamera;
> > +
> > +class PyCameraManager
> > +{
> > +public:
> > + PyCameraManager();
> > + ~PyCameraManager();
> > +
> > + pybind11::list cameras();
> > + std::shared_ptr<Camera> get(const std::string &name) { return cameraManager_->get(name); }
>
> Do you need to include <memory> ?
> > +
> > + static const std::string &version() { return CameraManager::version(); }
>
> Do you need to include <string>
>
> Should this method be marked as const ?
>
> > +
> > + int eventFd() const { return eventFd_; }
> > +
> > + std::vector<pybind11::object> getReadyRequests();
>
> Do you need to include vector ?
> > +
> > + void handleRequestCompleted(Request *req);
> > +
> > +private:
> > + std::unique_ptr<CameraManager> cameraManager_;
> > +
> > + int eventFd_ = -1;
> > + std::mutex completedRequestsMutex_;
> > + std::vector<Request *> completedRequests_;
> > +
> > + void writeFd();
> > + void readFd();
> > + void pushRequest(Request *req);
> > + std::vector<Request *> getCompletedRequests();
> > +};
> > diff --git a/src/py/libcamera/py_main.cpp b/src/py/libcamera/py_main.cpp
> > index e652837f..e7d078b5 100644
> > --- a/src/py/libcamera/py_main.cpp
> > +++ b/src/py/libcamera/py_main.cpp
> > @@ -7,10 +7,7 @@
> >
> > #include "py_main.h"
> >
> > -#include <mutex>
> > #include <stdexcept>
> > -#include <sys/eventfd.h>
> > -#include <unistd.h>
> >
> > #include <libcamera/base/log.h>
> >
> > @@ -21,6 +18,7 @@
> > #include <pybind11/stl.h>
> > #include <pybind11/stl_bind.h>
> >
> > +#include "py_camera_manager.h"
> > #include "py_helpers.h"
> >
> > namespace py = pybind11;
> > @@ -33,27 +31,11 @@ LOG_DEFINE_CATEGORY(Python)
> >
> > }
> >
> > -static std::weak_ptr<CameraManager> gCameraManager;
> > -static int gEventfd;
> > -static std::mutex gReqlistMutex;
> > -static std::vector<Request *> gReqList;
> > -
> > -static void handleRequestCompleted(Request *req)
> > -{
> > - {
> > - std::lock_guard guard(gReqlistMutex);
> > - gReqList.push_back(req);
> > - }
> > -
> > - uint64_t v = 1;
> > - size_t s = write(gEventfd, &v, 8);
> > - /*
> > - * We should never fail, and have no simple means to manage the error,
> > - * so let's log a fatal error.
> > - */
> > - if (s != 8)
> > - LOG(Python, Fatal) << "Unable to write to eventfd";
> > -}
> > +/*
> > + * Note: global C++ destructors can be ran on this before the py module is
> > + * destructed.
> > + */
> > +static std::weak_ptr<PyCameraManager> gCameraManager;
> >
> > void init_py_enums(py::module &m);
> > void init_py_controls_generated(py::module &m);
> > @@ -76,7 +58,7 @@ PYBIND11_MODULE(_libcamera, m)
> > * https://pybind11.readthedocs.io/en/latest/advanced/misc.html#avoiding-c-types-in-docstrings
> > */
> >
> > - auto pyCameraManager = py::class_<CameraManager>(m, "CameraManager");
> > + auto pyCameraManager = py::class_<PyCameraManager>(m, "CameraManager");
> > auto pyCamera = py::class_<Camera>(m, "Camera");
> > auto pyCameraConfiguration = py::class_<CameraConfiguration>(m, "CameraConfiguration");
> > auto pyCameraConfigurationStatus = py::enum_<CameraConfiguration::Status>(pyCameraConfiguration, "Status");
> > @@ -110,78 +92,22 @@ PYBIND11_MODULE(_libcamera, m)
> > /* Classes */
> > pyCameraManager
> > .def_static("singleton", []() {
> > - std::shared_ptr<CameraManager> cm = gCameraManager.lock();
> > - if (cm)
> > - return cm;
> > -
> > - int fd = eventfd(0, 0);
> > - if (fd == -1)
> > - throw std::system_error(errno, std::generic_category(),
> > - "Failed to create eventfd");
> > -
> > - cm = std::shared_ptr<CameraManager>(new CameraManager, [](auto p) {
> > - close(gEventfd);
> > - gEventfd = -1;
> > - delete p;
> > - });
> > -
> > - gEventfd = fd;
> > - gCameraManager = cm;
> > -
> > - int ret = cm->start();
> > - if (ret)
> > - throw std::system_error(-ret, std::generic_category(),
> > - "Failed to start CameraManager");
> > -
> > - return cm;
> > - })
> > -
> > - .def_property_readonly("version", &CameraManager::version)
> > + std::shared_ptr<PyCameraManager> cm = gCameraManager.lock();
> >
> > - .def_property_readonly("event_fd", [](CameraManager &) {
> > - return gEventfd;
> > - })
> > -
> > - .def("get_ready_requests", [](CameraManager &) {
> > - uint8_t buf[8];
> > -
> > - if (read(gEventfd, buf, 8) != 8)
> > - throw std::system_error(errno, std::generic_category());
> > -
> > - std::vector<Request *> v;
> > -
> > - {
> > - std::lock_guard guard(gReqlistMutex);
> > - swap(v, gReqList);
> > + if (!cm) {
> > + cm = std::make_shared<PyCameraManager>();
> > + gCameraManager = cm;
>
> What is the advantage of using a weak_ptr<> here ? Can't this be kept
> as a shared_ptr ?
>
> > }
> >
> > - std::vector<py::object> ret;
> > -
> > - for (Request *req : v) {
> > - py::object o = py::cast(req);
> > - /* Decrease the ref increased in Camera.queue_request() */
> > - o.dec_ref();
> > - ret.push_back(o);
> > - }
> > -
> > - return ret;
> > + return cm;
> > })
> >
> > - .def("get", py::overload_cast<const std::string &>(&CameraManager::get), py::keep_alive<0, 1>())
> > -
> > - /* Create a list of Cameras, where each camera has a keep-alive to CameraManager */
> > - .def_property_readonly("cameras", [](CameraManager &self) {
> > - py::list l;
> > -
> > - for (auto &c : self.cameras()) {
> > - py::object py_cm = py::cast(self);
> > - py::object py_cam = py::cast(c);
> > - py::detail::keep_alive_impl(py_cam, py_cm);
> > - l.append(py_cam);
> > - }
> > + .def_property_readonly("version", &PyCameraManager::version)
> > + .def("get", &PyCameraManager::get, py::keep_alive<0, 1>())
> > + .def_property_readonly("cameras", &PyCameraManager::cameras)
> >
> > - return l;
> > - });
> > + .def_property_readonly("event_fd", &PyCameraManager::eventFd)
>
> Is access to eventfs useful for applications ?
>
> > + .def("get_ready_requests", &PyCameraManager::getReadyRequests);
> >
> > pyCamera
> > .def_property_readonly("id", &Camera::id)
> > @@ -191,7 +117,10 @@ PYBIND11_MODULE(_libcamera, m)
> > const std::unordered_map<const ControlId *, py::object> &controls) {
> > /* \todo What happens if someone calls start() multiple times? */
> >
> > - self.requestCompleted.connect(handleRequestCompleted);
> > + auto cm = gCameraManager.lock();
> > + ASSERT(cm);
> > +
> > + self.requestCompleted.connect(cm.get(), &PyCameraManager::handleRequestCompleted);
> >
> > ControlList controlList(self.controls());
> >
> > @@ -202,7 +131,7 @@ PYBIND11_MODULE(_libcamera, m)
> >
> > int ret = self.start(&controlList);
> > if (ret) {
> > - self.requestCompleted.disconnect(handleRequestCompleted);
> > + self.requestCompleted.disconnect();
> > return ret;
> > }
> >
> > @@ -214,7 +143,7 @@ PYBIND11_MODULE(_libcamera, m)
> > if (ret)
> > return ret;
> >
> > - self.requestCompleted.disconnect(handleRequestCompleted);
> > + self.requestCompleted.disconnect();
> >
> > return 0;
> > })
--
Regards,
Laurent Pinchart
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