Attempts to workaround a race condition between daemon thread and
GDBus worker thread during shutdown.
Ubuntu bug: https://bugs.launchpad.net/bugs/2127049
I've not been able to get a symbolic backtrace yet or reproduce it
myself, but the behaviour points to a threading bug. Hypothesis,
Main thread (1, daemon thread) shuts down, unregistering its plugins.
One of the plugins, module-permissions-portal, is triggered to
shutdown.
It tries to clear its GDBus connection handle without disconnecting
its signal handlers.
GDBus thread (2) is in the middle of writing a message on the same
connection handle.
Once finished, it also tries to clear its handle.
The main thread has already taken the signal lock and the signal
handler table ends up in an invalid state, triggering the assert.
I believe this could happen since
wp_portal_permissionstore_plugin_disable is not disconnecting its
signal handlers before trying to clear its DBus object.
See https://bugzilla.gnome.org/show_bug.cgi?id=730296 for more
discussion about this assert in the Glib signal handling code.
Now that we have proper module load order, we can have this shared
dbus connection in a module instead of the library. The module has
to be loaded before any other modules that need it, obviously.
The intention is to make checks for enabled log topics faster.
Every topic has its own structure that is statically defined in the file
where the logs are printed from. The structure is initialized transparently
when it is first used and it contains all the log level flags for the levels
that this topic should print messages. It is then checked on the wp_log()
macro before printing the message.
Topics from SPA/PipeWire are also handled natively, so messages are printed
directly without checking if the topic is enabled, since the PipeWire and SPA
macros do the checking themselves.
Messages coming from GLib are checked inside the handler.
An internal WpLogFields object is used to manage the state of each log
message, populating all the fields appropriately from the place they
are coming from (wp_log, spa_log, glib log), formatting the message and
then printing it. For printing to the journald, we still use the glib
message handler, converting all the needed fields to GLogField on demand.
That message handler does not do any checks for the topic or the level, so
we can just call it to send the message.
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.
