py: Create PyCameraManager

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@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

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',

src/py/libcamera/py_camera_manager.cpp

@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+ */
+
+#include "py_camera_manager.h"
+
+#include <errno.h>
+#include <memory>
+#include <sys/eventfd.h>
+#include <system_error>
+#include <unistd.h>
+#include <vector>
+
+#include "py_main.h"
+
+namespace py = pybind11;
+
+using namespace libcamera;
+
+PyCameraManager::PyCameraManager()
+{
+	LOG(Python, Debug) << "PyCameraManager()";
+
+	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;
+
+	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;
+}
+
+std::vector<py::object> PyCameraManager::getReadyRequests()
+{
+	readFd();
+
+	std::vector<py::object> py_reqs;
+
+	for (Request *request : getCompletedRequests()) {
+		py::object o = py::cast(request);
+		/* Decrease the ref increased in Camera.queue_request() */
+		o.dec_ref();
+		py_reqs.push_back(o);
+	}
+
+	return py_reqs;
+}
+
+/* Note: Called from another thread */
+void PyCameraManager::handleRequestCompleted(Request *req)
+{
+	pushRequest(req);
+	writeFd();
+}
+
+void PyCameraManager::writeFd()
+{
+	uint64_t v = 1;
+
+	size_t s = write(eventFd_, &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";
+}
+
+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;
+}

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@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); }
+
+	static const std::string &version() { return CameraManager::version(); }
+
+	int eventFd() const { return eventFd_; }
+
+	std::vector<pybind11::object> getReadyRequests();
+
+	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();
+};

src/py/libcamera/py_main.cpp

@@ -7,10 +7,10 @@
 
 #include "py_main.h"
 
-#include <mutex>
+#include <memory>
 #include <stdexcept>
-#include <sys/eventfd.h>
+#include <string>
-#include <unistd.h>
+#include <vector>
 
 #include <libcamera/base/log.h>
 
@@ -21,6 +21,7 @@
 #include <pybind11/stl.h>
 #include <pybind11/stl_bind.h>
 
+#include "py_camera_manager.h"
 #include "py_helpers.h"
 
 namespace py = pybind11;
@@ -33,27 +34,11 @@ LOG_DEFINE_CATEGORY(Python)
 
 }
 
-static std::weak_ptr<CameraManager> gCameraManager;
+/*
-static int gEventfd;
+ * Note: global C++ destructors can be ran on this before the py module is
-static std::mutex gReqlistMutex;
+ * destructed.
-static std::vector<Request *> gReqList;
+ */
-
+static std::weak_ptr<PyCameraManager> gCameraManager;
-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";
-}
 
 void init_py_enums(py::module &m);
 void init_py_controls_generated(py::module &m);
@@ -76,7 +61,7 @@ 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 +95,22 @@ PYBIND11_MODULE(_libcamera, m)
 	/* Classes */
 	pyCameraManager
 		.def_static("singleton", []() {
-			std::shared_ptr<CameraManager> cm = gCameraManager.lock();
+			std::shared_ptr<PyCameraManager> cm = gCameraManager.lock();
-			if (cm)
-				return cm;
 
-			int fd = eventfd(0, 0);
+			if (!cm) {
-			if (fd == -1)
+				cm = std::make_shared<PyCameraManager>();
-				throw std::system_error(errno, std::generic_category(),
+				gCameraManager = cm;
-							"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)
+		.def_property_readonly("version", &PyCameraManager::version)
+		.def("get", &PyCameraManager::get, py::keep_alive<0, 1>())
+		.def_property_readonly("cameras", &PyCameraManager::cameras)
 
-		.def_property_readonly("event_fd", [](CameraManager &) {
+		.def_property_readonly("event_fd", &PyCameraManager::eventFd)
-			return gEventfd;
+		.def("get_ready_requests", &PyCameraManager::getReadyRequests);
-		})
-
-		.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);
-			}
-
-			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;
-		})
-
-		.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);
-			}
-
-			return l;
-		});
 
 	pyCamera
 		.def_property_readonly("id", &Camera::id)
@@ -191,7 +120,10 @@ 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 +134,7 @@ PYBIND11_MODULE(_libcamera, m)
 
 			int ret = self.start(&controlList);
 			if (ret) {
-				self.requestCompleted.disconnect(handleRequestCompleted);
+				self.requestCompleted.disconnect();
 				return ret;
 			}
 
@@ -214,7 +146,7 @@ PYBIND11_MODULE(_libcamera, m)
 			if (ret)
 				return ret;
 
-			self.requestCompleted.disconnect(handleRequestCompleted);
+			self.requestCompleted.disconnect();
 
 			return 0;
 		})