Tracking: Re-write marker request function

There are two main things.

First, remove the marker index caching. Thins makes it possible to
safely use function from a threaded environment.

Second, replace linear search with binary search, which speeds up
random lookup.

There is no measurable difference in the stabilization which had a
comment about caching nature of track lookup. The random lookup
complexity changed from O(N) to O(log N). In practice this also
unlikely to be measurable, but thread-safety worth it.

1 files changed, 1 insertions, 5 deletions

diff --git a/source/blender/blenkernel/intern/tracking_stabilize.c b/source/blender/blenkernel/intern/tracking_stabilize.c
index 6f58416924f..46589a578a8 100644
--- a/source/blender/blenkernel/intern/tracking_stabilize.c
+++ b/source/blender/blenkernel/intern/tracking_stabilize.c
@@ -311,11 +311,7 @@ static void retrieve_next_lower_usable_frame(
  * translation stabilization, which has an enabled tracking marker at this very
  * frame. We search both for the next lower and next higher position, to allow
  * the caller to interpolate gaps and to extrapolate at the ends of the
- * definition range.
- *
- * NOTE: Regarding performance note that the individual tracks will cache the
- *       last search position.
- */
+ * definition range. */
 static void find_next_working_frames(StabContext *ctx,
                                      int framenr,
                                      int *next_lower,