sub: uglify sub decoder with locking

The plan is to make the whole OSD thread-safe, and we start with this.

We just put locks on all entry points (fortunately, dec_sub.c and all
sd_*.c decoders are very closed off, and only the entry points in
dec_sub.h let you access it). I think this is pretty ugly, but at least
it's very simple.

There's a special case with sub_get_bitmaps(): this function returns
pointers to decoder data (specifically, libass images). There's no way
to synchronize this internally, so expose sub_lock/sub_unlock functions.

To make things simpler, and especially because the lock is sort-of
exposed to the outside world, make the locks recursive. Although the
only case where this is actually needed (although trivial) is
sub_set_extradata().

One corner case are ASS subtitles: for some reason, we keep a single
ASS_Renderer instance for subtitles around (probably to avoid rescanning
fonts with ordered chapters), and this ASS_Renderer instance is not
synchronized. Also, demux_libass.c loads ASS_Track objects, which are
directly passed to sd_ass.c. These things are not synchronized (and
would be hard to synchronize), and basically we're out of luck. But I
think for now, accesses happen reasonably serialized, so there is no
actual problem yet, even if we start to access OSD from other threads.

1 files changed, 6 insertions, 1 deletions

diff --git a/player/sub.c b/player/sub.c
index 734cbcf7e4..6d39ef2299 100644
--- a/player/sub.c
+++ b/player/sub.c
@@ -136,10 +136,15 @@ static void update_subtitle(struct MPContext *mpctx, int order)
 
     // Handle displaying subtitles on terminal; never done for secondary subs
     if (order == 0) {
-        if (!osd_obj->render_bitmap_subs || !mpctx->video_out)
+        if (!osd_obj->render_bitmap_subs || !mpctx->video_out) {
+            sub_lock(dec_sub);
             set_osd_subtitle(mpctx, sub_get_text(dec_sub, curpts_s));
+            sub_unlock(dec_sub);
+        }
     } else if (order == 1) {
+        sub_lock(dec_sub);
         osd_set_sub(mpctx->osd, osd_obj, sub_get_text(dec_sub, curpts_s));
+        sub_unlock(dec_sub);
     }
 }