The point of this file was to be easily usable by applications that want
to generate capture files (or proxy them). The intention here is that we
only have SpCaptureReader/SpCaptureWriter (and associated bits necessary
to support that).
This makes sure that we do not use GObject from the libsysprof-capture-2.a
while still having GType's in the libsysprof-2.so dynamic library.
We also invert the GObject macro check so that the default is to not
register a GType which increases the chances that copy/paste code does
not run into double-registering a GType if used with an application that
links against libsysprof-2. (One such example could be if Gtk uses this
code for timers, as it would break Sysprof itself).
Max uint was more than we allow, since we steal the top 8 bits for some
other data. This instead checks for 24-bit and warns if the user tries to
store a counter value that was not registered.
We have an annoying issue where we look at all fiends of a counter values
chunk in the counter set frame. So we need those values set to zero. If
we are passed fewer counter values than can fit in the frame, we leave
some of that data uninitialized. This ensures that it is cleared.
This allows grouping marks together so that the UI can present marks within
the same group in the same visualizer row.
The goal here is that our perf stream with drm data will have "drm" or some
similar group name (resulting in one row). mutter/cogl/gnome-shell will
use the thread-id as the group name (or something else that is useful) so
their events are grouped together. gdk-wayland might have it's own group
name as well.
The end result is that we can get a mark row for each series of related
data.
The goal here is to have an API that allows us to record things like
frame timing data. We might iterate on this API a bit, but this gets us
started.
A SpCaptureMark with a zero duration should be treated like an epoch mark
once a visualizer is created. SpCaptureMark with a non-zero duration should
be treated like a begin/end of operation. This may be useful in generating
something like a flame graph.
This allows external tooling to write capture files that Sysprof can open.
Ideally, this will get used by GJS in the near future to implement profiler
output for Sysprof.
The lib/ directory was getting a bit out of hand, so this tries
to organize things a bit so it is easier going forward to locate
the code people want to patch.
