module_loader: Split app initialization into separate steps

- Loading module is only for importing python modules and determining the order
in which they should be loaded.

- Initializing apps will create the instances which involves just creating the
components of the apps.

- Post initialization involves connecting to signals, running configuration
fixes, etc.

Tests:

- All apps that have post initialization step have been tested.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/__main__.py

@@ -112,6 +112,7 @@ def main():
         module_loader.include_urls()
         menu.init()
         module_loader.load_modules()
+        module_loader.apps_init()
         list_dependencies(arguments.list_dependencies)
 
     log.init()
@@ -129,6 +130,8 @@ def main():
     menu.init()
 
     module_loader.load_modules()
+    module_loader.apps_init()
+    module_loader.apps_post_init()
     frontpage.add_custom_shortcuts()
 
     if arguments.setup is not False:

plinth/module_loader.py

@@ -66,15 +66,9 @@ def load_modules():
         except KeyError:
             logger.error('Unsatified dependency for module - %s', module_name)
 
-    logger.info('Initializing apps - %s', ', '.join(ordered_modules))
-
     for module_name in ordered_modules:
-        _initialize_module(module_name, modules[module_name])
         loaded_modules[module_name] = modules[module_name]
 
-    logger.debug('App initialization completed.')
-    post_module_loading.send_robust(sender="module_loader")
-
 
 def _insert_modules(module_name, module, remaining_modules, ordered_modules):
     """Insert modules into a list based on dependency order"""
@@ -118,6 +112,13 @@ def _include_module_urls(module_import_path, module_name):
             raise
 
 
+def apps_init():
+    """Create apps by constructing them with components."""
+    logger.info('Initializing apps - %s', ', '.join(loaded_modules))
+    for module_name, module in loaded_modules.items():
+        _initialize_module(module_name, module)
+
+
 def _initialize_module(module_name, module):
     """Perform module initialization"""
 
@@ -131,10 +132,6 @@ def _initialize_module(module_name, module):
         ]
         if module_classes and app_class:
             module.app = app_class[0][1]()
-
-            if module.setup_helper.get_state(
-            ) != 'needs-setup' and module.app.is_enabled():
-                module.app.set_enabled(True)
     except Exception as exception:
         logger.exception('Exception while running init for %s: %s', module,
                          exception)
@@ -142,6 +139,27 @@ def _initialize_module(module_name, module):
             raise
 
 
+def apps_post_init():
+    """Run post initialization on each app."""
+    for module in loaded_modules.values():
+        if not hasattr(module, 'app') or not module.app:
+            continue
+
+        try:
+            module.app.post_init()
+            if module.setup_helper.get_state(
+            ) != 'needs-setup' and module.app.is_enabled():
+                module.app.set_enabled(True)
+        except Exception as exception:
+            logger.exception('Exception while running post init for %s: %s',
+                             module, exception)
+            if cfg.develop:
+                raise
+
+    logger.debug('App initialization completed.')
+    post_module_loading.send_robust(sender="module_loader")
+
+
 def get_modules_to_load():
     """Get the list of modules to be loaded"""
     global _modules_to_load