Stop looping execution (#4516)

* fix the problem when new scene events come during execution of a tree and execution start looping
* make scene handler close to impossible to cancel to prevent events which are impossible to handle

core/group_update_system.py

@@ -30,7 +30,9 @@ def control_center(event):
         for main_tree in trees_graph[event.tree]:
             us.UpdateTree.get(main_tree).add_outdated(trees_graph[main_tree, event.tree])
             if main_tree.sv_process:
-                ts.tasks.add(ts.Task(main_tree, us.UpdateTree.main_update(main_tree)))
+                ts.tasks.add(ts.Task(main_tree,
+                                     us.UpdateTree.main_update(main_tree),
+                                     is_scene_update=False))
 
     # topology of a group tree was changed
     elif type(event) is ev.GroupTreeEvent:
@@ -40,7 +42,9 @@ def control_center(event):
         for main_tree in trees_graph[event.tree]:
             us.UpdateTree.get(main_tree).add_outdated(trees_graph[main_tree, event.tree])
             if main_tree.sv_process:
-                ts.tasks.add(ts.Task(main_tree, us.UpdateTree.main_update(main_tree)))
+                ts.tasks.add(ts.Task(main_tree,
+                                     us.UpdateTree.main_update(main_tree),
+                                     is_scene_update=False))
 
     # Connections between trees were changed
     elif type(event) is ev.TreesGraphEvent:

core/tasks.py

@@ -36,13 +36,23 @@ def __bool__(self):
 
     def add(self, task: 'Task'):
         """Add new tasks to run them via timer"""
+
+        if task.is_scene_update:
+            # scene event can be excepted only as first event
+            # in all other cases it can be generated by tree evaluation
+            # and can lead to infinite loop of updates
+            if self._current is not None:
+                return
+
+        # print(f"Add {task=}")
         self._todo.add(task)
 
     @profile(section="UPDATE")
     def run(self):
         """Run given tasks to update trees and report execution process in the
         header of a node tree editor"""
-        max_duration = 0.15  # 0.15 is max timer frequency
+        # 0.15 is max timer frequency
+        max_duration = 10 if self.current.is_scene_update else 0.15
         duration = 0
 
         while self.current:
@@ -153,13 +163,14 @@ class Task:
     """Generator which should update some node tree. The task is hashable, and
     it is equal to another task if booth of them update the same tree.
     The generator is suspendable and can limit its execution by given time"""
-    def __init__(self, tree, updater):
+    def __init__(self, tree, updater, is_scene_update):
         """:tree: tree which should be updated
         :_updater: generator which should update given tree
         :is_exhausted: the status of the generator - read only
         :last_node: last node which going to be processed by the generator
         - read only"""
         self.tree: SvTree = tree
+        self.is_scene_update: bool = is_scene_update
         self.is_exhausted = False
         self.last_node = None
 

core/update_system.py

@@ -43,19 +43,25 @@ def control_center(event):
     elif type(event) is ev.SceneEvent:
         if event.tree.sv_scene_update and event.tree.sv_process:
             UpdateTree.get(event.tree).is_scene_updated = False
-            ts.tasks.add(ts.Task(event.tree, UpdateTree.main_update(event.tree)))
+            ts.tasks.add(ts.Task(event.tree,
+                                 UpdateTree.main_update(event.tree),
+                                 is_scene_update=True))
 
     # nodes changed properties
     elif type(event) is ev.PropertyEvent:
         tree = UpdateTree.get(event.tree)
         tree.add_outdated(event.updated_nodes)
         if event.tree.sv_process:
-            ts.tasks.add(ts.Task(event.tree, UpdateTree.main_update(event.tree)))
+            ts.tasks.add(ts.Task(event.tree,
+                                 UpdateTree.main_update(event.tree),
+                                 is_scene_update=False))
 
     # update the whole tree anyway
     elif type(event) is ev.ForceEvent:
         UpdateTree.reset_tree(event.tree)
-        ts.tasks.add(ts.Task(event.tree, UpdateTree.main_update(event.tree)))
+        ts.tasks.add(ts.Task(event.tree,
+                             UpdateTree.main_update(event.tree),
+                             is_scene_update=False))
 
     # mark that the tree topology has changed
     # also this can be called (by Blender) during undo event in this case all
@@ -64,7 +70,9 @@ def control_center(event):
     elif type(event) is ev.TreeEvent:
         UpdateTree.get(event.tree).is_updated = False
         if event.tree.sv_process:
-            ts.tasks.add(ts.Task(event.tree, UpdateTree.main_update(event.tree)))
+            ts.tasks.add(ts.Task(event.tree,
+                                 UpdateTree.main_update(event.tree),
+                                 is_scene_update=False))
 
     # new file opened
     elif type(event) is ev.FileEvent: