fix: support async function tracing in trace_call and trace_function (#595)

backend/app/rag/tracing.py

@@ -57,6 +57,28 @@ def _build_traceable(name: str, run_type: str, metadata: Optional[dict[str, Any]
         return _langsmith_traceable(name=name, run_type=run_type)
 
 
+import inspect
+
+async def async_trace_call(
+    name: str,
+    fn: Callable[..., Any],
+    *args: Any,
+    run_type: str = "chain",
+    metadata: Optional[dict[str, Any]] = None,
+    **kwargs: Any,
+) -> Any:
+    """Execute an asynchronous callable with LangSmith tracing when available."""
+    if not LANGSMITH_ENABLED:
+        return await fn(*args, **kwargs)
+
+    decorator = _build_traceable(name, run_type, metadata)
+    if decorator is None:
+        return await fn(*args, **kwargs)
+
+    traced_fn = decorator(fn)
+    return await traced_fn(*args, **kwargs)
+
+
 def trace_call(
     name: str,
     fn: Callable[..., Any],
@@ -65,7 +87,10 @@ def trace_call(
     metadata: Optional[dict[str, Any]] = None,
     **kwargs: Any,
 ) -> Any:
-    """Execute a callable with LangSmith tracing when available."""
+    """Execute a callable with LangSmith tracing when available. Supports both sync and async."""
+    if inspect.iscoroutinefunction(fn):
+        return async_trace_call(name, fn, *args, run_type=run_type, metadata=metadata, **kwargs)
+
     if not LANGSMITH_ENABLED:
         return fn(*args, **kwargs)
 
@@ -83,8 +108,22 @@ def trace_function(
     run_type: str = "chain",
     metadata_factory: Optional[Callable[..., dict[str, Any]]] = None,
 ) -> Callable[[Callable[..., Any]], Callable[..., Any]]:
-    """Decorator wrapper that becomes a no-op when LangSmith is disabled."""
+    """Decorator wrapper that becomes a no-op when LangSmith is disabled. Supports both sync and async."""
     def decorator(fn: Callable[..., Any]) -> Callable[..., Any]:
+        if inspect.iscoroutinefunction(fn):
+            @wraps(fn)
+            async def async_wrapped(*args: Any, **kwargs: Any) -> Any:
+                metadata = metadata_factory(*args, **kwargs) if metadata_factory else None
+                return await trace_call(
+                    name,
+                    fn,
+                    *args,
+                    run_type=run_type,
+                    metadata=metadata,
+                    **kwargs,
+                )
+            return async_wrapped
+
         @wraps(fn)
         def wrapped(*args: Any, **kwargs: Any) -> Any:
             metadata = metadata_factory(*args, **kwargs) if metadata_factory else None
@@ -96,7 +135,6 @@ def wrapped(*args: Any, **kwargs: Any) -> Any:
                 metadata=metadata,
                 **kwargs,
             )
-
         return wrapped
 
-    return decorator
+    return decorator