on_retriever_start() — langchain Function Reference

Architecture documentation for the on_retriever_start() function in base.py from the langchain codebase.

Function python Observability Tracers calls 3 called by 1

Entity Profile

Observability→ Tracers→ on_retriever_start() — langchain Function Reference

Dependency Diagram

graph TD
  34d4aff3_df37_afe5_eda8_47ac51eeebe3["on_retriever_start()"]
  b3ab8001_c14c_4191_ca53_2dbabc99917f["AsyncBaseTracer"]
  34d4aff3_df37_afe5_eda8_47ac51eeebe3 -->|defined in| b3ab8001_c14c_4191_ca53_2dbabc99917f
  bf4d8a61_6642_64fa_e8e9_3dcdfaf802ca["on_retriever_start()"]
  bf4d8a61_6642_64fa_e8e9_3dcdfaf802ca -->|calls| 34d4aff3_df37_afe5_eda8_47ac51eeebe3
  6f36dacc_adf3_1223_4aff_3ae256a05ed8["_start_trace()"]
  34d4aff3_df37_afe5_eda8_47ac51eeebe3 -->|calls| 6f36dacc_adf3_1223_4aff_3ae256a05ed8
  936f68f6_447f_a14f_b3cf_7e3383599589["_on_retriever_start()"]
  34d4aff3_df37_afe5_eda8_47ac51eeebe3 -->|calls| 936f68f6_447f_a14f_b3cf_7e3383599589
  bf4d8a61_6642_64fa_e8e9_3dcdfaf802ca["on_retriever_start()"]
  34d4aff3_df37_afe5_eda8_47ac51eeebe3 -->|calls| bf4d8a61_6642_64fa_e8e9_3dcdfaf802ca
  style 34d4aff3_df37_afe5_eda8_47ac51eeebe3 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/tracers/base.py lines 803–828

    async def on_retriever_start(
        self,
        serialized: dict[str, Any],
        query: str,
        *,
        run_id: UUID,
        parent_run_id: UUID | None = None,
        tags: list[str] | None = None,
        metadata: dict[str, Any] | None = None,
        name: str | None = None,
        **kwargs: Any,
    ) -> None:
        retriever_run = self._create_retrieval_run(
            serialized=serialized,
            query=query,
            run_id=run_id,
            parent_run_id=parent_run_id,
            tags=tags,
            metadata=metadata,
            name=name,
        )
        tasks = [
            self._start_trace(retriever_run),
            self._on_retriever_start(retriever_run),
        ]
        await asyncio.gather(*tasks)