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authorHirokazu Honda <hiroh@chromium.org>2021-12-01 16:53:47 +0900
committerLaurent Pinchart <laurent.pinchart@ideasonboard.com>2021-12-01 13:46:57 +0200
commit221cf408f316eb2dc1cb96986053e2005fd36f39 (patch)
treee6e9dba5a027a174fcdab95015c6d98b31420482 /src/qcam/assets/feathericons/globe.svg
parentf6807016a37fc11f8c93f105569f04fa1a2326e7 (diff)
android: camera_device: Add thread safety annotation
This applies clang thread safety annotation to CameraDevice. Signed-off-by: Hirokazu Honda <hiroh@chromium.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Umang Jain <umang.jain@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2018, Google Inc.
 *
 * camera_manager.h - Camera management
 */

#include <libcamera/camera_manager.h>

#include <condition_variable>
#include <map>

#include <libcamera/camera.h>
#include <libcamera/event_dispatcher.h>

#include "libcamera/internal/device_enumerator.h"
#include "libcamera/internal/event_dispatcher_poll.h"
#include "libcamera/internal/ipa_manager.h"
#include "libcamera/internal/log.h"
#include "libcamera/internal/pipeline_handler.h"
#include "libcamera/internal/thread.h"
#include "libcamera/internal/utils.h"

/**
 * \file camera_manager.h
 * \brief The camera manager
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(Camera)

class CameraManager::Private : public Thread
{
public:
	Private(CameraManager *cm);

	int start();
	void addCamera(std::shared_ptr<Camera> &camera,
		       const std::vector<dev_t> &devnums);
	void removeCamera(Camera *camera);

	/*
	 * This mutex protects
	 *
	 * - initialized_ and status_ during initialization
	 * - cameras_ and camerasByDevnum_ after initialization
	 */
	Mutex mutex_;
	std::vector<std::shared_ptr<Camera>> cameras_;
	std::map<dev_t, std::weak_ptr<Camera>> camerasByDevnum_;

protected:
	void run() override;

private:
	int init();
	void cleanup();

	CameraManager *cm_;

	std::condition_variable cv_;
	bool initialized_;
	int status_;

	std::vector<std::shared_ptr<PipelineHandler>> pipes_;
	std::unique_ptr<DeviceEnumerator> enumerator_;

	IPAManager ipaManager_;
};

CameraManager::Private::Private(CameraManager *cm)
	: cm_(cm), initialized_(false)
{
}

int CameraManager::Private::start()
{
	int status;

	/* Start the thread and wait for initialization to complete. */
	Thread::start();

	{
		MutexLocker locker(mutex_);
		cv_.wait(locker, [&] { return initialized_; });
		status = status_;
	}

	/* If a failure happened during initialization, stop the thread. */
	if (status < 0) {
		exit();
		wait();
		return status;
	}

	return 0;
}

void CameraManager::Private::run()
{
	LOG(Camera, Debug) << "Starting camera manager";

	int ret = init();

	mutex_.lock();
	status_ = ret;
	initialized_ = true;
	mutex_.unlock();
	cv_.notify_one();

	if (ret < 0)
		return;

	/* Now start processing events and messages. */
	exec();

	cleanup();
}

int CameraManager::Private::init()
{
	enumerator_ = DeviceEnumerator::create();
	if (!enumerator_ || enumerator_->enumerate())
		return -ENODEV;

	/*
	 * TODO: Try to read handlers and order from configuration
	 * file and only fallback on all handlers if there is no
	 * configuration file.
	 */
	std::vector<PipelineHandlerFactory *> &factories = PipelineHandlerFactory::factories();

	for (PipelineHandlerFactory *factory : factories) {
		/*
		 * Try each pipeline handler until it exhaust
		 * all pipelines it can provide.
		 */
		while (1) {
			std::shared_ptr<PipelineHandler> pipe = factory->create(cm_);
			if (!pipe->match(enumerator_.get()))
				break;

			LOG(Camera, Debug)
				<< "Pipeline handler \"" << factory->name()
				<< "\" matched";
			pipes_.push_back(std::move(pipe));
		}
	}

	/* TODO: register hot-plug callback here */

	return 0;
}

void CameraManager::Private::cleanup()
{
	/* TODO: unregister hot-plug callback here */

	/*
	 * Release all references to cameras and pipeline handlers to ensure
	 * they all get destroyed before the device enumerator deletes the
	 * media devices.
	 */
	pipes_.clear();
	cameras_.clear();

	enumerator_.reset(nullptr);
}

void CameraManager::Private::addCamera(std::shared_ptr<Camera> &camera,
				       const std::vector<dev_t> &devnums)
{
	MutexLocker locker(mutex_);

	for (std::shared_ptr<Camera> c : cameras_) {
		if (c->name() == camera->name()) {
			LOG(Camera, Warning)
				<< "Registering camera with duplicate name '"
				<< camera->name() << "'";
			break;
		}
	}

	cameras_.push_back(std::move(camera));

	unsigned int index = cameras_.size() - 1;
	for (dev_t devnum : devnums)
		camerasByDevnum_[devnum] = cameras_[index];
}

void CameraManager::Private::removeCamera(Camera *camera)
{
	MutexLocker locker(mutex_);

	auto iter = std::find_if(cameras_.begin(), cameras_.end(),
				 [camera](std::shared_ptr<Camera> &c) {
					 return c.get() == camera;
				 });
	if (iter == cameras_.end())
		return;

	LOG(Camera, Debug)
		<< "Unregistering camera '" << camera->name() << "'";

	auto iter_d = std::find_if(camerasByDevnum_.begin(), camerasByDevnum_.end(),
				   [camera](const std::pair<dev_t, std::weak_ptr<Camera>> &p) {
					   return p.second.lock().get() == camera;
				   });
	if (iter_d != camerasByDevnum_.end())
		camerasByDevnum_.erase(iter_d);

	cameras_.erase(iter);
}

/**
 * \class CameraManager
 * \brief Provide access and manage all cameras in the system
 *
 * The camera manager is the entry point to libcamera. It enumerates devices,
 * associates them with pipeline managers, and provides access to the cameras
 * in the system to applications. The manager owns all Camera objects and
 * handles hot-plugging and hot-unplugging to manage the lifetime of cameras.
 *
 * To interact with libcamera, an application starts by creating a camera
 * manager instance. Only a single instance of the camera manager may exist at
 * a time. Attempting to create a second instance without first deleting the
 * existing instance results in undefined behaviour.
 *
 * The manager is initially stopped, and shall be configured before being
 * started. In particular a custom event dispatcher shall be installed if
 * needed with CameraManager::setEventDispatcher().
 *
 * Once the camera manager is configured, it shall be started with start().
 * This will enumerate all the cameras present in the system, which can then be
 * listed with list() and retrieved with get().
 *
 * Cameras are shared through std::shared_ptr<>, ensuring that a camera will
 * stay valid until the last reference is released without requiring any special
 * action from the application. Once the application has released all the
 * references it held to cameras, the camera manager can be stopped with
 * stop().
 *
 * \todo Add interface to register a notification callback to the user to be
 * able to inform it new cameras have been hot-plugged or cameras have been
 * removed due to hot-unplug.
 */

CameraManager *CameraManager::self_ = nullptr;

CameraManager::CameraManager()
	: p_(new CameraManager::Private(this))
{
	if (self_)
		LOG(Camera, Fatal)
			<< "Multiple CameraManager objects are not allowed";

	self_ = this;
}

CameraManager::~CameraManager()
{
	stop();

	self_ = nullptr;
}

/**
 * \brief Start the camera manager
 *
 * Start the camera manager and enumerate all devices in the system. Once
 * the start has been confirmed the user is free to list and otherwise
 * interact with cameras in the system until either the camera manager
 * is stopped or the camera is unplugged from the system.
 *
 * \return 0 on success or a negative error code otherwise
 */
int CameraManager::start()
{
	LOG(Camera, Info) << "libcamera " << version_;

	int ret = p_->start();
	if (ret)
		LOG(Camera, Error) << "Failed to start camera manager: "
				   << strerror(-ret);

	return ret;
}

/**
 * \brief Stop the camera manager
 *
 * Before stopping the camera manager the caller is responsible for making
 * sure all cameras provided by the manager are returned to the manager.
 *
 * After the manager has been stopped no resource provided by the camera
 * manager should be consider valid or functional even if they for one