Add polling and reload callback for extensions.

modules/script_callbacks.py

@@ -74,21 +74,36 @@ def __init__(self, imgs, cols, rows):
     callbacks_infotext_pasted=[],
     callbacks_script_unloaded=[],
     callbacks_before_ui=[],
+    callbacks_on_reload=[],
+    callbacks_on_polling=[],
 )
 
 
 def clear_callbacks():
     for callback_list in callback_map.values():
         callback_list.clear()
 
-
 def app_started_callback(demo: Optional[Blocks], app: FastAPI):
     for c in callback_map['callbacks_app_started']:
         try:
             c.callback(demo, app)
         except Exception:
             report_exception(c, 'app_started_callback')
 
+def app_polling_callback(demo: Optional[Blocks], app: FastAPI):
+    for c in callback_map['callbacks_on_polling']:
+        try:
+            c.callback()
+        except Exception:
+            report_exception(c, 'callbacks_on_polling')
+
+def app_reload_callback(demo: Optional[Blocks], app: FastAPI):
+    for c in callback_map['callbacks_on_reload']:
+        try:
+            c.callback()
+        except Exception:
+            report_exception(c, 'callbacks_on_reload')
+
 
 def model_loaded_callback(sd_model):
     for c in callback_map['callbacks_model_loaded']:
@@ -227,6 +242,14 @@ def on_app_started(callback):
     add_callback(callback_map['callbacks_app_started'], callback)
 
 
+def on_polling(callback):
+    """register a function to be called on each polling of the server."""
+    add_callback(callback_map['callbacks_on_polling'], callback)
+
+def on_before_reload(callback):
+    """register a function to be called just before the server reloads."""
+    add_callback(callback_map['callbacks_on_reload'], callback)
+
 def on_model_loaded(callback):
     """register a function to be called when the stable diffusion model is created; the model is
     passed as an argument; this function is also called when the script is reloaded. """

webui.py

@@ -171,7 +171,9 @@ def create_api(app):
 def wait_on_server(demo=None):
     while 1:
         time.sleep(0.5)
+        modules.script_callbacks.app_polling_callback(None, demo)
         if shared.state.need_restart:
+            modules.script_callbacks.app_reload_callback(None, demo)
             shared.state.need_restart = False
             time.sleep(0.5)
             demo.close()