Support for async execution functions

This commit adds support for node execution functions defined as async. When
a node's execution function is defined as async, we can continue
executing other nodes while it is processing.

Standard uses of `await` should "just work", but people will still have
to be careful if they spawn actual threads. Because torch doesn't really
have async/await versions of functions, this won't particularly help
with most locally-executing nodes, but it does work for e.g. web
requests to other machines.

In addition to the execute function, the `VALIDATE_INPUTS` and
`check_lazy_status` functions can also be defined as async, though we'll
only resolve one node at a time right now for those.

main.py

@@ -11,6 +11,8 @@ import itertools
 import utils.extra_config
 import logging
 import sys
+from comfy_execution.progress import get_progress_state
+from comfy_execution.utils import get_executing_context
 
 if __name__ == "__main__":
     #NOTE: These do not do anything on core ComfyUI, they are for custom nodes.
@@ -128,7 +130,7 @@ import comfy.utils
 
 import execution
 import server
-from server import BinaryEventTypes
+from protocol import BinaryEventTypes
 import nodes
 import comfy.model_management
 import comfyui_version
@@ -218,14 +220,25 @@ async def run(server_instance, address='', port=8188, verbose=True, call_on_star
         server_instance.start_multi_address(addresses, call_on_start, verbose), server_instance.publish_loop()
     )
 
-
 def hijack_progress(server_instance):
-    def hook(value, total, preview_image):
+    def hook(value, total, preview_image, prompt_id=None, node_id=None):
+        executing_context = get_executing_context()
+        if prompt_id is None and executing_context is not None:
+            prompt_id = executing_context.prompt_id
+        if node_id is None and executing_context is not None:
+            node_id = executing_context.node_id
         comfy.model_management.throw_exception_if_processing_interrupted()
-        progress = {"value": value, "max": total, "prompt_id": server_instance.last_prompt_id, "node": server_instance.last_node_id}
+        if prompt_id is None:
+            prompt_id = server_instance.last_prompt_id
+        if node_id is None:
+            node_id = server_instance.last_node_id
+        progress = {"value": value, "max": total, "prompt_id": prompt_id, "node": node_id}
+        get_progress_state().update_progress(node_id, value, total, preview_image)
 
         server_instance.send_sync("progress", progress, server_instance.client_id)
         if preview_image is not None:
+            # Also send old method for backward compatibility
+            # TODO - Remove after this repo is updated to frontend with metadata support
             server_instance.send_sync(BinaryEventTypes.UNENCODED_PREVIEW_IMAGE, preview_image, server_instance.client_id)
 
     comfy.utils.set_progress_bar_global_hook(hook)