Merge pull request #1645 from Ultimaker/CURA-9159_fix_threaded_tree_crash

[CURA-9159] Fix occasional crash due to unsafe threading in tree support.

3 files changed, 15 insertions, 5 deletions

diff --git a/src/TreeModelVolumes.cpp b/src/TreeModelVolumes.cpp
index 7479d5a82..1c6889ee8 100644
--- a/src/TreeModelVolumes.cpp
+++ b/src/TreeModelVolumes.cpp
@@ -104,6 +104,8 @@ const Polygons& TreeModelVolumes::calculateCollision(const RadiusLayerPair& key)
             collision_areas = collision_areas.unionPolygons(collision_model.offset(radius));
         }
     }
+
+    const std::lock_guard<std::mutex> lock(object_mutex_);
     const auto ret = collision_cache_.insert({key, std::move(collision_areas)});
     assert(ret.second);
     return ret.first->second;
@@ -135,6 +137,8 @@ const Polygons& TreeModelVolumes::calculateAvoidance(const RadiusLayerPair& key)
     }
     auto avoidance_areas = getAvoidance(radius, layer_idx - 1).offset(-max_move_).smooth(5);
     avoidance_areas = avoidance_areas.unionPolygons(getCollision(radius, layer_idx));
+
+    const std::lock_guard<std::mutex> lock(object_mutex_);
     const auto ret = avoidance_cache_.insert({key, std::move(avoidance_areas)});
     assert(ret.second);
     return ret.first->second;
@@ -144,8 +148,9 @@ const Polygons& TreeModelVolumes::calculateInternalModel(const RadiusLayerPair&
 {
     const auto& radius = key.first;
     const auto& layer_idx = key.second;
-
     const auto& internal_areas = getAvoidance(radius, layer_idx).difference(getCollision(radius, layer_idx));
+
+    const std::lock_guard<std::mutex> lock(object_mutex_);
     const auto ret = internal_model_cache_.insert({key, internal_areas});
     assert(ret.second);
     return ret.first->second;
diff --git a/src/TreeModelVolumes.h b/src/TreeModelVolumes.h
index 74f2b4cc3..29d23b0d6 100644
--- a/src/TreeModelVolumes.h
+++ b/src/TreeModelVolumes.h
@@ -4,6 +4,7 @@
 #ifndef TREEMODELVOLUMES_H
 #define TREEMODELVOLUMES_H
 
+#include <mutex>
 #include <unordered_map>
 
 #include "settings/EnumSettings.h" //To store whether X/Y or Z distance gets priority.
@@ -20,7 +21,7 @@ class Settings;
 /*!
  * \brief Lazily generates tree guidance volumes.
  *
- * \warning This class is not currently thread-safe and should not be accessed in OpenMP blocks
+ * \warning This class blocks on thread access. Use calls to this in threaded blocks sparingly.
  */
 class TreeModelVolumes
 {
@@ -195,6 +196,11 @@ private:
     mutable std::unordered_map<RadiusLayerPair, Polygons> collision_cache_;
     mutable std::unordered_map<RadiusLayerPair, Polygons> avoidance_cache_;
     mutable std::unordered_map<RadiusLayerPair, Polygons> internal_model_cache_;
+
+    /*!
+     * \brief Used to make the class thread-safe.
+     */
+    mutable std::mutex object_mutex_;
 };
 
 }
diff --git a/src/TreeSupport.cpp b/src/TreeSupport.cpp
index 6edfa7f29..278cd3e16 100644
--- a/src/TreeSupport.cpp
+++ b/src/TreeSupport.cpp
@@ -31,10 +31,9 @@
 namespace cura
 {
 
-TreeSupport::TreeSupport(const SliceDataStorage& storage)
+TreeSupport::TreeSupport(const SliceDataStorage& storage) :
+    volumes_(storage, Application::getInstance().current_slice->scene.current_mesh_group->settings)
 {
-    const Settings& mesh_group_settings = Application::getInstance().current_slice->scene.current_mesh_group->settings;
-    volumes_ = TreeModelVolumes(storage, mesh_group_settings);
 }
 
 void TreeSupport::generateSupportAreas(SliceDataStorage& storage)