The Doxygen "Modules" page is not very illuminative, as different parts
of the API are mixed together and not all parts are included.
Try to address this:
Put all parts of the public API to some Doxygen group, usually one group
per header file. Use short, systematic names.
Make these groups sub-groups of a few top-level groups, roughly
corresponding to the different logical parts of the API (core, impl,
stream, filter, spa, utilities).
Subdirectories buffer, control, debug, monitor, pod, support and utils, others
are still missing. Headers are grouped either per subdirectory (e.g. buffer/
gets added to group spa_buffer) or per-file (e.g. spa_json is a separate
group), whatever seemed like the most sensible approach.
Because the signal can't be removed from the callback we can
simply iterate backwards and then forwards.
The first added hook (the unlock/lock pair) is called last before
going into the poll and first when leaving. This executes all other
callbacks inside a locked situation. And removing them with the lock
is not going to cause problems.
Make a method to find the memory block for the given ptr. We can
use this to find the memfd of the memory if there is any. We can
then remove the Shared metadata on buffers.
