From 21ff749a790386f87e767a690c77948a6474ceaa Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Thu, 17 Jan 2019 16:23:25 +0200 Subject: libcamera: camera: Handle camera objects through shared pointers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The Camera class is explicitly reference-counted to manage the lifetime of camera objects. Replace this open-coded implementation with usage of the std::shared_ptr<> class. This API change prevents pipeline handlers from subclassing the Camera class. This isn't deemed to be an issue. Mark the class final to make this explicit. Signed-off-by: Laurent Pinchart Reviewed-by: Jacopo Mondi Reviewed-by: Niklas Söderlund --- src/libcamera/camera.cpp | 46 +++++++++++++++++++++++----------------- src/libcamera/camera_manager.cpp | 24 ++++++++++----------- src/libcamera/pipeline/vimc.cpp | 4 ++-- 3 files changed, 40 insertions(+), 34 deletions(-) (limited to 'src/libcamera') diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp index 6da2b201..acf912be 100644 --- a/src/libcamera/camera.cpp +++ b/src/libcamera/camera.cpp @@ -41,19 +41,36 @@ namespace libcamera { * streams from a single image source. It provides the main interface to * configuring and controlling the device, and capturing image streams. It is * the central object exposed by libcamera. + * + * To support the central nature of Camera objects, libcamera manages the + * lifetime of camera instances with std::shared_ptr<>. Instances shall be + * created with the create() function which returns a shared pointer. The + * Camera constructors and destructor are private, to prevent instances from + * being constructed and destroyed manually. */ /** - * \brief Construct a named camera device + * \brief Create a camera instance + * \param[in] name The name of the camera device * - * \param[in] name The name to set on the camera device + * The caller is responsible for guaranteeing unicity of the camera name. * - * The caller is responsible for guaranteeing unicity of the camera - * device name. + * \return A shared pointer to the newly created camera object */ -Camera::Camera(const std::string &name) - : ref_(1), name_(name) +std::shared_ptr Camera::create(const std::string &name) { + struct Allocator : std::allocator { + void construct(void *p, const std::string &name) + { + ::new(p) Camera(name); + } + void destroy(Camera *p) + { + p->~Camera(); + } + }; + + return std::allocate_shared(Allocator(), name); } /** @@ -66,24 +83,13 @@ const std::string &Camera::name() const return name_; } -/** - * \brief Acquire a reference to the camera - */ -void Camera::get() +Camera::Camera(const std::string &name) + : name_(name) { - ref_++; } -/** - * \brief Release a reference to the camera - * - * When the last reference is released the camera device is deleted. Callers - * shall not access the camera device after calling this function. - */ -void Camera::put() +Camera::~Camera() { - if (--ref_ == 0) - delete this; } } /* namespace libcamera */ diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp index 3fa9f23c..d76eaa7a 100644 --- a/src/libcamera/camera_manager.cpp +++ b/src/libcamera/camera_manager.cpp @@ -40,9 +40,11 @@ namespace libcamera { * This will enumerate all the cameras present in the system, which can then be * listed with list() and retrieved with get(). * - * Cameras are reference-counted, and shall be returned to the camera manager - * with Camera::put() after being used. Once all cameras have been returned to - * the manager, it can be stopped with stop(). + * 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 ability to add and remove media devices based on hot-(un)plug * events coming from the device enumerator. @@ -148,15 +150,13 @@ void CameraManager::stop() * \param[in] name Name of camera to get * * Before calling this function the caller is responsible for ensuring that - * the camera manger is running. A camera fetched this way shall be - * released by the user with the put() method of the Camera object once - * it is done using the camera. + * the camera manger is running. * - * \return Pointer to Camera object or nullptr if camera not found + * \return Shared pointer to Camera object or nullptr if camera not found */ -Camera *CameraManager::get(const std::string &name) +std::shared_ptr CameraManager::get(const std::string &name) { - for (Camera *camera : cameras_) { + for (std::shared_ptr camera : cameras_) { if (camera->name() == name) return camera; } @@ -172,9 +172,9 @@ Camera *CameraManager::get(const std::string &name) * handle with the camera manager. Registered cameras are immediately made * available to the system. */ -void CameraManager::addCamera(Camera *camera) +void CameraManager::addCamera(std::shared_ptr camera) { - for (Camera *c : cameras_) { + for (std::shared_ptr c : cameras_) { if (c->name() == camera->name()) { LOG(Warning) << "Registering camera with duplicate name '" << camera->name() << "'"; @@ -182,7 +182,7 @@ void CameraManager::addCamera(Camera *camera) } } - cameras_.push_back(camera); + cameras_.push_back(std::move(camera)); } /** diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp index 8742e0ba..82b9237a 100644 --- a/src/libcamera/pipeline/vimc.cpp +++ b/src/libcamera/pipeline/vimc.cpp @@ -64,8 +64,8 @@ bool PipeHandlerVimc::match(CameraManager *manager, DeviceEnumerator *enumerator * will be chosen depends on how the Camera * object is modeled. */ - Camera *camera = new Camera("Dummy VIMC Camera"); - manager->addCamera(camera); + std::shared_ptr camera = Camera::create("Dummy VIMC Camera"); + manager->addCamera(std::move(camera)); return true; } -- cgit v1.2.1