Fix material model update and signal recursion

CURA-6904

cura/Machines/Models/BaseMaterialsModel.py

@@ -1,9 +1,9 @@
 # Copyright (c) 2019 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
-from typing import Optional, Dict, Set
+from typing import Dict, Set
 
-from PyQt5.QtCore import Qt, pyqtSignal, pyqtProperty
+from PyQt5.QtCore import Qt, QTimer, pyqtSignal, pyqtProperty
 
 from UM.Qt.ListModel import ListModel
 
@@ -38,14 +38,25 @@ class BaseMaterialsModel(ListModel):
         self._extruder_stack = None
         self._enabled = True
 
+        # CURA-6904
+        # Updating the material model requires information from material nodes and containers. We use a timer here to
+        # make sure that an update function call will not be directly invoked by an event. Because the triggered event
+        # can be caused in the middle of a XMLMaterial loading, and the material container we try to find may not be
+        # in the system yet. This will cause an infinite recursion of (1) trying to load a material, (2) trying to
+        # update the material model, (3) cannot find the material container, load it, (4) repeat #1.
+        self._update_timer = QTimer()
+        self._update_timer.setInterval(100)
+        self._update_timer.setSingleShot(True)
+        self._update_timer.timeout.connect(self._update)
+
         # Update the stack and the model data when the machine changes
         self._machine_manager.globalContainerChanged.connect(self._updateExtruderStack)
         self._updateExtruderStack()
 
         # Update this model when switching machines, when adding materials or changing their metadata.
-        self._machine_manager.activeStackChanged.connect(self._update)
+        self._machine_manager.activeStackChanged.connect(self._onChanged)
         ContainerTree.getInstance().materialsChanged.connect(self._materialsListChanged)
-        self._application.getMaterialManagementModel().favoritesChanged.connect(self._update)
+        self._application.getMaterialManagementModel().favoritesChanged.connect(self._onChanged)
 
         self.addRoleName(Qt.UserRole + 1, "root_material_id")
         self.addRoleName(Qt.UserRole + 2, "id")
@@ -64,14 +75,17 @@ class BaseMaterialsModel(ListModel):
         self.addRoleName(Qt.UserRole + 15, "container_node")
         self.addRoleName(Qt.UserRole + 16, "is_favorite")
 
+    def _onChanged(self) -> None:
+        self._update_timer.start()
+
     def _updateExtruderStack(self):
         global_stack = self._machine_manager.activeMachine
         if global_stack is None:
             return
 
         if self._extruder_stack is not None:
-            self._extruder_stack.pyqtContainersChanged.disconnect(self._update)
+            self._extruder_stack.pyqtContainersChanged.disconnect(self._onChanged)
-            self._extruder_stack.approximateMaterialDiameterChanged.disconnect(self._update)
+            self._extruder_stack.approximateMaterialDiameterChanged.disconnect(self._onChanged)
 
         try:
             self._extruder_stack = global_stack.extruderList[self._extruder_position]
@@ -79,10 +93,10 @@ class BaseMaterialsModel(ListModel):
             self._extruder_stack = None
 
         if self._extruder_stack is not None:
-            self._extruder_stack.pyqtContainersChanged.connect(self._update)
+            self._extruder_stack.pyqtContainersChanged.connect(self._onChanged)
-            self._extruder_stack.approximateMaterialDiameterChanged.connect(self._update)
+            self._extruder_stack.approximateMaterialDiameterChanged.connect(self._onChanged)
         # Force update the model when the extruder stack changes
-        self._update()
+        self._onChanged()
 
     def setExtruderPosition(self, position: int):
         if self._extruder_stack is None or self._extruder_position != position:
@@ -99,7 +113,7 @@ class BaseMaterialsModel(ListModel):
             self._enabled = enabled
             if self._enabled:
                 # ensure the data is there again.
-                self._update()
+                self._onChanged()
             self.enabledChanged.emit()
 
     @pyqtProperty(bool, fset = setEnabled, notify = enabledChanged)
@@ -119,12 +133,12 @@ class BaseMaterialsModel(ListModel):
             return
         if material.variant.machine.container_id != global_stack.definition.getId():
             return
-        self._update()
+        self._onChanged()
 
     ##  Triggered when the list of favorite materials is changed.
     def _favoritesChanged(self, material_base_file: str) -> None:
         if material_base_file in self._available_materials:
-            self._update()
+            self._onChanged()
 
     ## This is an abstract method that needs to be implemented by the specific
     #  models themselves.

cura/Machines/Models/FavoriteMaterialsModel.py

@@ -9,14 +9,14 @@ class FavoriteMaterialsModel(BaseMaterialsModel):
     def __init__(self, parent = None):
         super().__init__(parent)
         cura.CuraApplication.CuraApplication.getInstance().getPreferences().preferenceChanged.connect(self._onFavoritesChanged)
-        self._update()
+        self._onChanged()
 
     ##  Triggered when any preference changes, but only handles it when the list
     #   of favourites is changed.
     def _onFavoritesChanged(self, preference_key: str) -> None:
         if preference_key != "cura/favorite_materials":
             return
-        self._update()
+        self._onChanged()
 
     def _update(self):
         if not self._canUpdate():

cura/Machines/Models/GenericMaterialsModel.py

@@ -7,7 +7,7 @@ class GenericMaterialsModel(BaseMaterialsModel):
 
     def __init__(self, parent = None):
         super().__init__(parent)
-        self._update()
+        self._onChanged()
 
     def _update(self):
         if not self._canUpdate():