fix: langfuse trace get the right parent span (#6844)

* fix: langfuse trace get the right parent span

* [autofix.ci] apply automated fixes

* fix: langfuse callback from parent span

* [autofix.ci] apply automated fixes

---------

Co-authored-by: tianzhipeng-jk <tianzhipeng-jk@360shuke.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Ítalo Johnny <italojohnnydosanjos@gmail.com>

src/backend/base/langflow/services/tracing/langfuse.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import os
+from collections import OrderedDict
 from datetime import datetime, timezone
 from typing import TYPE_CHECKING, Any
 
@@ -14,7 +15,6 @@ if TYPE_CHECKING:
     from uuid import UUID
 
     from langchain.callbacks.base import BaseCallbackHandler
-    from langfuse.client import StatefulSpanClient
 
     from langflow.graph.vertex.base import Vertex
     from langflow.services.tracing.schema import Log
@@ -29,8 +29,7 @@ class LangFuseTracer(BaseTracer):
         self.trace_type = trace_type
         self.trace_id = trace_id
         self.flow_id = trace_name.split(" - ")[-1]
-        self.last_span: StatefulSpanClient | None = None
+        self.spans: dict = OrderedDict()  # spans that are not ended
-        self.spans: dict = {}
 
         config = self._get_config()
         self._ready: bool = self.setup_langfuse(config) if config else False
@@ -42,18 +41,10 @@ class LangFuseTracer(BaseTracer):
     def setup_langfuse(self, config) -> bool:
         try:
             from langfuse import Langfuse
-            from langfuse.callback.langchain import LangchainCallbackHandler
 
             self._client = Langfuse(**config)
             self.trace = self._client.trace(id=str(self.trace_id), name=self.flow_id)
 
-            config |= {
-                "trace_name": self.flow_id,
-                "stateful_client": self.trace,
-                "update_stateful_client": True,
-            }
-            self._callback = LangchainCallbackHandler(**config)
-
         except ImportError:
             logger.exception("Could not import langfuse. Please install it with `pip install langfuse`.")
             return False
@@ -67,7 +58,7 @@ class LangFuseTracer(BaseTracer):
     @override
     def add_trace(
         self,
-        trace_id: str,
+        trace_id: str,  # actualy component id
         trace_name: str,
         trace_type: str,
         inputs: dict[str, Any],
@@ -90,9 +81,12 @@ class LangFuseTracer(BaseTracer):
             "start_time": start_time,
         }
 
-        span = self.last_span.span(**content_span) if self.last_span else self.trace.span(**content_span)
+        if len(self.spans) > 0:
+            last_span = next(reversed(self.spans))
+            span = self.spans[last_span].span(**content_span)
+        else:
+            span = self.trace.span(**content_span)
 
-        self.last_span = span
         self.spans[trace_id] = span
 
     @override
@@ -108,7 +102,7 @@ class LangFuseTracer(BaseTracer):
         if not self._ready:
             return
 
-        span = self.spans.get(trace_id, None)
+        span = self.spans.pop(trace_id, None)
         if span:
             output: dict = {}
             output |= outputs or {}
@@ -133,7 +127,10 @@ class LangFuseTracer(BaseTracer):
     def get_langchain_callback(self) -> BaseCallbackHandler | None:
         if not self._ready:
             return None
-        return self._callback
+
+        # get callback from parent span
+        stateful_client = self.spans[next(reversed(self.spans))] if len(self.spans) > 0 else self.trace
+        return stateful_client.get_langchain_handler()
 
     @staticmethod
     def _get_config() -> dict: