From b776c46d2f67dffd36e2a68a1152c0f0d7bef7e6 Mon Sep 17 00:00:00 2001
From: Brecht Van Lommel <brecht@blender.org>
Date: Mon, 17 Jan 2022 20:36:59 +0100
Subject: Fix T94715: multiple volumes using the same .vdb causes freeze

Needs more TBB task isolation, as even freeing an OpenVDB grid uses
multithreading.
---
 source/blender/blenkernel/intern/volume.cc | 40 +++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 14 deletions(-)

(limited to 'source/blender/blenkernel/intern/volume.cc')

diff --git a/source/blender/blenkernel/intern/volume.cc b/source/blender/blenkernel/intern/volume.cc
index c17706dc216..579526a051f 100644
--- a/source/blender/blenkernel/intern/volume.cc
+++ b/source/blender/blenkernel/intern/volume.cc
@@ -138,11 +138,19 @@ static struct VolumeFileCache {
       }
 
       std::lock_guard<std::mutex> lock(mutex);
-      return simplified_grids.lookup_or_add_cb(simplify_level, [&]() {
-        const float resolution_factor = 1.0f / (1 << simplify_level);
-        const VolumeGridType grid_type = BKE_volume_grid_type_openvdb(*grid);
-        return BKE_volume_grid_create_with_changed_resolution(grid_type, *grid, resolution_factor);
+      openvdb::GridBase::Ptr simple_grid;
+
+      /* Isolate creating grid since that's multithreaded and we are
+       * holding a mutex lock. */
+      blender::threading::isolate_task([&] {
+        simple_grid = simplified_grids.lookup_or_add_cb(simplify_level, [&]() {
+          const float resolution_factor = 1.0f / (1 << simplify_level);
+          const VolumeGridType grid_type = BKE_volume_grid_type_openvdb(*grid);
+          return BKE_volume_grid_create_with_changed_resolution(
+              grid_type, *grid, resolution_factor);
+        });
       });
+      return simple_grid;
     }
 
     /* Unique key: filename + grid name. */
@@ -247,16 +255,20 @@ static struct VolumeFileCache {
  protected:
   void update_for_remove_user(Entry &entry)
   {
-    if (entry.num_metadata_users + entry.num_tree_users == 0) {
-      cache.erase(entry);
-    }
-    else if (entry.num_tree_users == 0) {
-      /* Note we replace the grid rather than clearing, so that if there is
-       * any other shared pointer to the grid it will keep the tree. */
-      entry.grid = entry.grid->copyGridWithNewTree();
-      entry.simplified_grids.clear();
-      entry.is_loaded = false;
-    }
+    /* Isolate file unloading since that's multithreaded and we are
+     * holding a mutex lock. */
+    blender::threading::isolate_task([&] {
+      if (entry.num_metadata_users + entry.num_tree_users == 0) {
+        cache.erase(entry);
+      }
+      else if (entry.num_tree_users == 0) {
+        /* Note we replace the grid rather than clearing, so that if there is
+         * any other shared pointer to the grid it will keep the tree. */
+        entry.grid = entry.grid->copyGridWithNewTree();
+        entry.simplified_grids.clear();
+        entry.is_loaded = false;
+      }
+    });
   }
 
   /* Cache contents */
-- 
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