Each component can optionally "provide" a feature, which is basically
a string that describes the feature (ex. "support.dbus"). If the
component loads successfully, the feature is marked as provided and
can be tested for its presence with wp_core_test_feature()
There is no reason to return the component object... all components
are supposed to be long-lived objects that are referenced by the
registry and there is API to find them. The caller is only interested
in the success or failure of the operation.
Do this in wp_core_load_component() and let the component loaders worry
only about creating the object.
Also run the main loop in tests while loading components, to ensure
that the async operation finishes before continuing execution. GTask
makes sure to make the operation async always, by emitting the callback
from an idle GSource.
Regarding the core parameter, the case used to be that WpComponentLoader
was a WpPlugin, so it had a reference to the core internally, but since
this is no longer a requirement, we need to pass this explicitly
This change completely refactors the way components are loaded in wireplumber:
- The module_init() function must return a GObject now. This object is either
a WpPlugin or a WpSiFactory in the current modules.
- When the component loader initializes a module, it automatically registers
the WpPlugin or WpSiFactory with their respective methods. There is no need
to register the WpPlugin or WpSiFactory in the module now.
- The wp_core_load_component() API has been refactored to be asynchronows. This
allows the component loader to automatically activate WpPlugin objects, and
therefore allows the application to directly get the WpPlugin without having
to find it. This simplifies a lot of things.
- The 'ifexists' and 'nofail' component flags now work even if the respective
WpPlugin could not be activated.
- The code that loads components in main.c has also been simplified a lot,
and the option to load dangling components has also been removed.
This removes both the policy-virtual-client.lua and policy-virtual-device.lua
scripts, and creates a new linking/find-virtual-target.lua script to link
clients with virtual session items if one of them can be found. In addition to
this, this patch also ports the policy-virtual-client-links.lua into a new
scripts/rescan-virtual-links.lua to use the event stack. The idea is for the
scripts/link-target.lua to create all links but only activate non virtual links,
and for the scripts/rescan-virtual-links.lua to activate/deactivate virtual
links based on role priorities.
