Move constraints resolution off GUI thread

AddonManager.py

@@ -35,6 +35,7 @@
     GetBasicAddonStatsWorker,
     GetAddonScoreWorker,
     CheckForMissingDependenciesWorker,
+    LoadPythonConstraintsWorker,
 )
 from addonmanager_installer_gui import (
     AddonInstallerGUI,
@@ -108,6 +109,7 @@ class CommandAddonManager(QtCore.QObject):
         "get_basic_addon_stats_worker",
         "get_addon_score_worker",
         "check_missing_dependencies_worker",
+        "load_python_constraints_worker",
     ]
 
     lock = threading.Lock()
@@ -144,6 +146,7 @@ def __init__(self):
         self.get_addon_score_worker = None
         self.get_basic_addon_stats_worker = None
         self.check_missing_dependencies_worker = None
+        self.load_python_constraints_worker = None
 
         self.manage_python_packages_dialog = None
         self.missing_dependency_installer = None
@@ -350,6 +353,7 @@ def startup(self) -> None:
         # self.do_next_startup_phase if it is not launching a worker
         self.startup_sequence = [
             self.populate_packages_table,
+            self.load_python_constraints,
             self.activate_table_widgets,
             self.check_updates,
             self.check_missing_dependencies,
@@ -385,6 +389,14 @@ def populate_packages_table(self) -> None:
         self.create_addon_list_worker.progress_made.connect(self.update_progress_bar)
         self.create_addon_list_worker.start()
 
+    def load_python_constraints(self) -> None:
+        self.load_python_constraints_worker = LoadPythonConstraintsWorker()
+        self.update_progress_bar(
+            translate("AddonsInstaller", "Loading Python package constraints"), 0, 100
+        )
+        self.load_python_constraints_worker.finished.connect(self.do_next_startup_phase)
+        self.load_python_constraints_worker.start()
+
     def activate_table_widgets(self) -> None:
         self.composite_view.package_list.setEnabled(True)
         self.composite_view.package_list.ui.view_bar.search.setFocus()

AddonManagerTest/app/test_workers_startup.py

@@ -775,3 +775,13 @@ def test_missing_icon_is_not_fatal(self, mock_network_manager, _):
 
         self.assertEqual("My Custom Addon", addon.display_name)
         self.assertFalse(addon.icon_data)
+
+
+class TestLoadPythonConstraintsWorker(unittest.TestCase):
+
+    @patch("addonmanager_workers_startup.get_constraints")
+    def test_run_reloads_the_shared_constraints(self, mock_get_constraints):
+        """Running the worker fetches the constraints, so later GUI-thread users find them loaded."""
+        addonmanager_workers_startup.LoadPythonConstraintsWorker().run()
+
+        mock_get_constraints.return_value.reload.assert_called_once_with()

addonmanager_workers_startup.py

@@ -51,6 +51,7 @@
     get_branch_from_metadata,
     get_icon_from_metadata,
 )
+from addonmanager_python_constraints import get_constraints
 import addonmanager_utilities as utils
 import addonmanager_freecad_interface as fci
 
@@ -949,3 +950,11 @@ def run(self):
         else:
             fci.Console.PrintLog(message)
         fci.Console.PrintLog(details)
+
+
+class LoadPythonConstraintsWorker(QtCore.QThread):
+    """A worker class to fetch the vetted Python package constraints. This uses a blocking network
+    fetch, so cannot run on the main GUI thread."""
+
+    def run(self):
+        get_constraints().reload()