ao: avoid unnecessary wakeups

If ao_add_events() is used, but all events flags are already set, then
we don't need to wakeup the core again.

Also, make the underrun message "exact" by avoiding the race condition
mentioned in the comment.

Avoiding redundant wakeups is not really worth the trouble, and it's
actually just a bonus in the change making the ao_underrun_event()
function return whether a new underrun was set, which is needed by the
following commit.

1 files changed, 1 insertions, 1 deletions

diff --git a/audio/out/internal.h b/audio/out/internal.h
index d1d7482ec1..7d1d744991 100644
--- a/audio/out/internal.h
+++ b/audio/out/internal.h
@@ -211,7 +211,7 @@ struct pollfd;
 int ao_wait_poll(struct ao *ao, struct pollfd *fds, int num_fds,
                  pthread_mutex_t *lock);
 void ao_wakeup_poll(struct ao *ao);
-void ao_underrun_event(struct ao *ao);
+bool ao_underrun_event(struct ao *ao);
 
 bool ao_chmap_sel_adjust(struct ao *ao, const struct mp_chmap_sel *s,
                          struct mp_chmap *map);