Make @main_fn decorator support async functions. (#259)

Author: badmonster0

examples/gdrive_text_embedding/main.py

@@ -49,9 +49,9 @@ def gdrive_text_embedding_flow(flow_builder: cocoindex.FlowBuilder, data_scope:
     default_similarity_metric=cocoindex.VectorSimilarityMetric.COSINE_SIMILARITY)
 
 @cocoindex.main_fn()
-def _run():
+async def _run():
     # Use a `FlowLiveUpdater` to keep the flow data updated.
-    with cocoindex.FlowLiveUpdater(gdrive_text_embedding_flow):
+    async with cocoindex.FlowLiveUpdater(gdrive_text_embedding_flow):
         # Run queries in a loop to demonstrate the query capabilities.
         while True:
             try:
@@ -70,4 +70,5 @@ def _run():
 
 if __name__ == "__main__":
     load_dotenv(override=True)
-    _run()
+    import asyncio
+    asyncio.run(_run())

python/cocoindex/lib.py

@@ -1,10 +1,12 @@
 """
 Library level functions and states.
 """
-import json
 import os
 import sys
-from typing import Callable, Self
+import functools
+import inspect
+import asyncio
+from typing import Callable, Self, Any
 from dataclasses import dataclass
 
 from . import _engine
@@ -78,20 +80,40 @@ def main_fn(
 
     If the settings are not provided, they are loaded from the environment variables.
     """
-    def _main_wrapper(fn: Callable) -> Callable:
 
-        def _inner(*args, **kwargs):
-            effective_settings = settings or Settings.from_env()
-            init(effective_settings)
-            try:
-                if len(sys.argv) > 1 and sys.argv[1] == cocoindex_cmd:
-                    return cli.cli.main(sys.argv[2:], prog_name=f"{sys.argv[0]} {sys.argv[1]}")
-                else:
-                    return fn(*args, **kwargs)
-            finally:
-                stop()
+    def _pre_init() -> None:
+        effective_settings = settings or Settings.from_env()
+        init(effective_settings)
+
+    def _should_run_cli() -> bool:
+        return len(sys.argv) > 1 and sys.argv[1] == cocoindex_cmd
 
-        _inner.__name__ = fn.__name__
-        return _inner
+    def _run_cli():
+        return cli.cli.main(sys.argv[2:], prog_name=f"{sys.argv[0]} {sys.argv[1]}")
+
+    def _main_wrapper(fn: Callable) -> Callable:
+        if inspect.iscoroutinefunction(fn):
+            @functools.wraps(fn)
+            async def _inner(*args, **kwargs):
+                _pre_init()
+                try:
+                    if _should_run_cli():
+                        # Schedule to a separate thread as it invokes nested event loop.
+                        return await asyncio.to_thread(_run_cli)
+                    return await fn(*args, **kwargs)
+                finally:
+                    stop()
+            return _inner
+        else:
+            @functools.wraps(fn)
+            def _inner(*args, **kwargs):
+                _pre_init()
+                try:
+                    if _should_run_cli():
+                        return _run_cli()
+                    return fn(*args, **kwargs)
+                finally:
+                    stop()
+            return _inner
 
     return _main_wrapper