[Bf-blender-cvs] [9ae35fafb60] blender-v2.79-release: Fix T52149: LoopTriArray computation was not correctly protected against concurrency.
Bastien Montagne
noreply at git.blender.org
Fri Sep 8 12:08:28 CEST 2017
Commit: 9ae35fafb60e76a70c33d6236671a627ac458e4f
Author: Bastien Montagne
Date: Fri Aug 11 16:51:19 2017 +0200
Branches: blender-v2.79-release
https://developer.blender.org/rB9ae35fafb60e76a70c33d6236671a627ac458e4f
Fix T52149: LoopTriArray computation was not correctly protected against concurrency.
Note: this commit seems to work as expected (also with transform
snapping etc.). However, it is rather unsafe - not enough for 2.79 at
least, unless we get much more testing on it. It also depends on three
previous ones.
Note that using a global lock here is far from ideal, we should rather
have a lock per DM, but that will do for now, whole DM thing is doomed
to oblivion anyway in 2.8.
Also, we may need a `DM_DIRTY_LOOPTRIS` dirty flag at some point. Looks
like we can survive without it for now though... Probably because cached
looptris are never copied accross DM's?
===================================================================
M source/blender/blenkernel/BKE_DerivedMesh.h
M source/blender/blenkernel/intern/DerivedMesh.c
M source/blender/blenkernel/intern/subsurf_ccg.c
===================================================================
diff --git a/source/blender/blenkernel/BKE_DerivedMesh.h b/source/blender/blenkernel/BKE_DerivedMesh.h
index 5a4fdcf2510..e2577689101 100644
--- a/source/blender/blenkernel/BKE_DerivedMesh.h
+++ b/source/blender/blenkernel/BKE_DerivedMesh.h
@@ -220,7 +220,7 @@ struct DerivedMesh {
/** Recalculates mesh tessellation */
void (*recalcTessellation)(DerivedMesh *dm);
- /** Loop tessellation cache */
+ /** Loop tessellation cache (WARNING! Only call inside threading-protected code!) */
void (*recalcLoopTri)(DerivedMesh *dm);
/** accessor functions */
const struct MLoopTri *(*getLoopTriArray)(DerivedMesh * dm);
diff --git a/source/blender/blenkernel/intern/DerivedMesh.c b/source/blender/blenkernel/intern/DerivedMesh.c
index 7a05ab4530c..e53f14291b7 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.c
+++ b/source/blender/blenkernel/intern/DerivedMesh.c
@@ -93,6 +93,10 @@ static DerivedMesh *navmesh_dm_createNavMeshForVisualization(DerivedMesh *dm);
# define ASSERT_IS_VALID_DM(dm)
#endif
+
+static ThreadMutex loops_cache_lock = BLI_MUTEX_INITIALIZER;
+
+
static void add_shapekey_layers(DerivedMesh *dm, Mesh *me, Object *ob);
static void shapekey_layers_to_keyblocks(DerivedMesh *dm, Mesh *me, int actshape_uid);
@@ -241,7 +245,13 @@ static const MLoopTri *dm_getLoopTriArray(DerivedMesh *dm)
BLI_assert(dm->getNumLoopTri(dm) == dm->looptris.num);
}
else {
- dm->recalcLoopTri(dm);
+ BLI_mutex_lock(&loops_cache_lock);
+ /* We need to ensure array is still NULL inside mutex-protected code, some other thread might have already
+ * recomputed those looptris. */
+ if (dm->looptris.array == NULL) {
+ dm->recalcLoopTri(dm);
+ }
+ BLI_mutex_unlock(&loops_cache_lock);
}
return dm->looptris.array;
}
diff --git a/source/blender/blenkernel/intern/subsurf_ccg.c b/source/blender/blenkernel/intern/subsurf_ccg.c
index 47dea5ea282..ff0682258c6 100644
--- a/source/blender/blenkernel/intern/subsurf_ccg.c
+++ b/source/blender/blenkernel/intern/subsurf_ccg.c
@@ -4474,10 +4474,10 @@ static void ccgDM_recalcTessellation(DerivedMesh *UNUSED(dm))
/* Nothing to do: CCG handles creating its own tessfaces */
}
+/* WARNING! *MUST* be called in an 'loops_cache_rwlock' protected thread context! */
static void ccgDM_recalcLoopTri(DerivedMesh *dm)
{
- BLI_rw_mutex_lock(&loops_cache_rwlock, THREAD_LOCK_WRITE);
- MLoopTri *mlooptri;
+ MLoopTri *mlooptri = dm->looptris.array;
const int tottri = dm->numPolyData * 2;
int i, poly_index;
@@ -4502,7 +4502,6 @@ static void ccgDM_recalcLoopTri(DerivedMesh *dm)
lt->tri[2] = (poly_index * 4) + 2;
lt->poly = poly_index;
}
- BLI_rw_mutex_unlock(&loops_cache_rwlock);
}
static void ccgDM_calcNormals(DerivedMesh *dm)
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