add support for specifying callback order in metadata

modules/script_callbacks.py

@@ -8,7 +8,7 @@ from typing import Optional, Any
 from fastapi import FastAPI
 from gradio import Blocks
 
-from modules import errors, timer, extensions, shared
+from modules import errors, timer, extensions, shared, util
 
 
 def report_exception(c, job):
@@ -149,6 +149,38 @@ def add_callback(callbacks, fun, *, name=None, category='unknown', filename=None
 
 def sort_callbacks(category, unordered_callbacks, *, enable_user_sort=True):
     callbacks = unordered_callbacks.copy()
+    callback_lookup = {x.name: x for x in callbacks}
+    dependencies = {}
+
+    order_instructions = {}
+    for extension in extensions.extensions:
+        for order_instruction in extension.metadata.list_callback_order_instructions():
+            if order_instruction.name in callback_lookup:
+                if order_instruction.name not in order_instructions:
+                    order_instructions[order_instruction.name] = []
+
+                order_instructions[order_instruction.name].append(order_instruction)
+
+    if order_instructions:
+        for callback in callbacks:
+            dependencies[callback.name] = []
+
+        for callback in callbacks:
+            for order_instruction in order_instructions.get(callback.name, []):
+                for after in order_instruction.after:
+                    if after not in callback_lookup:
+                        continue
+
+                    dependencies[callback.name].append(after)
+
+                for before in order_instruction.before:
+                    if before not in callback_lookup:
+                        continue
+
+                    dependencies[before].append(callback.name)
+
+        sorted_names = util.topological_sort(dependencies)
+        callbacks = [callback_lookup[x] for x in sorted_names]
 
     if enable_user_sort:
         for name in reversed(getattr(shared.opts, 'prioritized_callbacks_' + category, [])):