NekoCWD/libcamera
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libcamera: camera: Add acquire() and release()

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Exclusive access must be obtained before performing operations that
change the device state. Define an internal flag to track ownership and
provide a means of protecting functions that change device
configuration.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Laurent Pinchart 2018-12-19 02:21:28 +02:00 • committed by Niklas Söderlund
parent 51d442d5a1
commit ff96eb2ebb
2 changed files with 43 additions and 1 deletions
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5
include/libcamera/camera.h
View file

@ -29,6 +29,9 @@ public:
Signal<Camera *> disconnected;
int acquire();
void release();
private:
Camera(PipelineHandler *pipe, const std::string &name);
~Camera();
@ -38,6 +41,8 @@ private:
std::shared_ptr<PipelineHandler> pipe_;
std::string name_;
bool acquired_;
};
} /* namespace libcamera */

39
src/libcamera/camera.cpp
View file

@ -102,12 +102,14 @@ const std::string &Camera::name() const
*/
Camera::Camera(PipelineHandler *pipe, const std::string &name)
: pipe_(pipe->shared_from_this()), name_(name)
: pipe_(pipe->shared_from_this()), name_(name), acquired_(false)
{
}
Camera::~Camera()
{
if (acquired_)
LOG(Camera, Error) << "Removing camera while still in use";
}
/**
@ -127,4 +129,39 @@ void Camera::disconnect()
disconnected.emit(this);
}
/**
* \brief Acquire the camera device for exclusive access
*
* After opening the device with open(), exclusive access must be obtained
* before performing operations that change the device state. This function is
* not blocking, if the device has already been acquired (by the same or another
* process) the -EBUSY error code is returned.
*
* Once exclusive access isn't needed anymore, the device should be released
* with a call to the release() function.
*
* \todo Implement exclusive access across processes.
*
* \return 0 on success or a negative error code on error.
*/
int Camera::acquire()
{
if (acquired_)
return -EBUSY;
acquired_ = true;
return 0;
}
/**
* \brief Release exclusive access to the camera device
*
* Releasing the camera device allows other users to acquire exclusive access
* with the acquire() function.
*/
void Camera::release()
{
acquired_ = false;
}
} /* namespace libcamera */