Refactor vertex building and streaming endpoints

src/backend/langflow/api/v1/chat.py

@@ -56,7 +56,22 @@ async def get_vertices(
     chat_service: "ChatService" = Depends(get_chat_service),
     session=Depends(get_session),
 ):
-    """Check the flow_id is in the flow_data_store."""
+    """
+    Retrieve the vertices order for a given flow.
+
+    Args:
+        flow_id (str): The ID of the flow.
+        stop_component_id (str, optional): The ID of the stop component. Defaults to None.
+        start_component_id (str, optional): The ID of the start component. Defaults to None.
+        chat_service (ChatService, optional): The chat service dependency. Defaults to Depends(get_chat_service).
+        session (Session, optional): The session dependency. Defaults to Depends(get_session).
+
+    Returns:
+        VerticesOrderResponse: The response containing the ordered vertex IDs and the run ID.
+
+    Raises:
+        HTTPException: If there is an error checking the build status.
+    """
     try:
         # First, we need to check if the flow_id is in the cache
         graph = None
@@ -100,7 +115,23 @@ async def build_vertex(
     chat_service: "ChatService" = Depends(get_chat_service),
     current_user=Depends(get_current_active_user),
 ):
-    """Build a vertex instead of the entire graph."""
+    """Build a vertex instead of the entire graph.
+
+    Args:
+        flow_id (str): The ID of the flow.
+        vertex_id (str): The ID of the vertex to build.
+        background_tasks (BackgroundTasks): The background tasks object for logging.
+        inputs (Optional[InputValueRequest], optional): The input values for the vertex. Defaults to None.
+        chat_service (ChatService, optional): The chat service dependency. Defaults to Depends(get_chat_service).
+        current_user (Any, optional): The current user dependency. Defaults to Depends(get_current_active_user).
+
+    Returns:
+        VertexBuildResponse: The response containing the built vertex information.
+
+    Raises:
+        HTTPException: If there is an error building the vertex.
+
+    """
 
     start_time = time.perf_counter()
     next_runnable_vertices = []
@@ -191,9 +222,6 @@ async def build_vertex(
         raise HTTPException(status_code=500, detail=str(exc)) from exc
 
 
-# Now onto an endpoint that is an SSE endpoint
-# it will receive a component_id and a flow_id
-#
 @router.get("/build/{flow_id}/{vertex_id}/stream", response_class=StreamingResponse)
 async def build_vertex_stream(
     flow_id: str,
@@ -202,7 +230,31 @@ async def build_vertex_stream(
     chat_service: "ChatService" = Depends(get_chat_service),
     session_service: "SessionService" = Depends(get_session_service),
 ):
-    """Build a vertex instead of the entire graph."""
+    """Build a vertex instead of the entire graph.
+
+    This function is responsible for building a single vertex instead of the entire graph.
+    It takes the `flow_id` and `vertex_id` as required parameters, and an optional `session_id`.
+    It also depends on the `ChatService` and `SessionService` services.
+
+    If `session_id` is not provided, it retrieves the graph from the cache using the `chat_service`.
+    If `session_id` is provided, it loads the session data using the `session_service`.
+
+    Once the graph is obtained, it retrieves the specified vertex using the `vertex_id`.
+    If the vertex does not support streaming, an error is raised.
+    If the vertex has a built result, it sends the result as a chunk.
+    If the vertex is not frozen or not built, it streams the vertex data.
+    If the vertex has a result, it sends the result as a chunk.
+    If none of the above conditions are met, an error is raised.
+
+    If any exception occurs during the process, an error message is sent.
+    Finally, the stream is closed.
+
+    Returns:
+        A `StreamingResponse` object with the streamed vertex data in text/event-stream format.
+
+    Raises:
+        HTTPException: If an error occurs while building the vertex.
+    """
     try:
 
         async def stream_vertex():