Sometimes the mixer is temporarily prevented from applying updates, when
multiple sources need to be updated simultaneously for example, but does not
prevent mixing. If the mixer runs during that time and a voice was just
started, it would've mixed the voice without any internal properties being set
for it.
Not all IDE parsers necessarily choke on restrict, and even those that do can
probably have their own configuration to define macros that can hide the
parsing errors caused by it.
perf shows a 5% drop in relative execution time on the alffplay example with an
audio-only file (20% to 15%). Kinda figured the optimizer would handle it
better, but I guess not.
This will also allow backends to better synchronize the tracked clock time with
the device output latency, without necessarily needing to lock if the backend
API can allow for it.
Since the wet path is essentially the room response to a sound, the direction
of the sound to the listener doesn't change the amount of energy the room
receives. Instead, the surface area defined by the cones dictate the volume the
room gets for the sound.
If an unapplied update was superceded, it would be placed in the freelist with
its effect state object intact. This would cause another update with the same
effect state object to be placed into the freelist as well, or worse, cause it
to get deleted while in use when the container had its effect state cleared.
This necessitates a change in how source updates are handled. Rather than just
being able to update sources when a dependent object state is changed (e.g. a
listener gain change), now all source updates must be proactively provided.
Consequently, apps that do not utilize any deferring (AL_SOFT_defer_updates or
alcSuspendContext/alcProcessContext) may utilize more CPU since it'll be
filling out more update containers for the mixer thread to use.
The upside is that there's less blocking between the app's calling thread and
the mixer thread, particularly for vectors and other multi-value properties
(filters and sends). Deferring behavior when used is also improved, since
updates that shouldn't be applied yet are simply not provided. And when they
are provided, the mixer doesn't have to ignore them, meaning the actual
deferring of a context doesn't have to synchrnously force an update -- the
process call will send any pending updates, which the mixer will apply even if
another deferral occurs before the mixer runs, because it'll still be there
waiting on the next mixer invocation.
There is one slight bug introduced by this commit. When a listener change is
made, or changes to multiple sources while updates are being deferred, it is
possible for the mixer to run while the sources are prepping their updates,
causing some of the source updates to be seen before the other. This will be
fixed in short order.
Chris Robinson