ref_initable_backend

Returns either a newly-created or existing Backend for Source.

The returned Backend is referenced for thread-safety and must be unreferenced with unref when finished with it.

If the newly-created backend implements the Initable interface, then init is also called on it using cancellable and throws.

The this retains a strong reference to backend.

If no suitable BackendFactory exists, or if the Backend fails to initialize, the function sets throws and returns null.

Parameters:

this	an SubprocessFactory
uid	UID of an Source to open
backend_factory_type_name	the name of the backend factory type
module_filename	the name (full-path) of the backend module to be loaded
cancellable	optional Cancellable object, or null

Returns:

an Backend for source, or null