core[patch]: fix no current event loop for sql history in async mode (#…

…22933)

- **Description:** When use
RunnableWithMessageHistory/SQLChatMessageHistory in async mode, we'll
get the following error:
```
Error in RootListenersTracer.on_chain_end callback: RuntimeError("There is no current event loop in thread 'asyncio_3'.")
```
which throwed by
https://github.com/langchain-ai/langchain/blob/ddfbca38dfa22954eaeda38614c6e1ec0cdecaa9/libs/community/langchain_community/chat_message_histories/sql.py#L259.
and no message history will be add to database.

In this patch, a new _aexit_history function which will'be called in
async mode is added, and in turn aadd_messages will be called.

In this patch, we use `afunc` attribute of a Runnable to check if the
end listener should be run in async mode or not.

  - **Issue:** #22021, #22022 
  - **Dependencies:** N/A

libs/community/langchain_community/chat_message_histories/sql.py

@@ -1,4 +1,3 @@
-import asyncio
 import contextlib
 import json
 import logging
@@ -252,17 +251,11 @@ async def aadd_message(self, message: BaseMessage) -> None:
  await session.commit()
 
  def add_messages(self, messages: Sequence[BaseMessage]) -> None:
- # The method RunnableWithMessageHistory._exit_history() call
- # add_message method by mistake and not aadd_message.
- # See https://github.com/langchain-ai/langchain/issues/22021
- if self.async_mode:
- loop = asyncio.get_event_loop()
- loop.run_until_complete(self.aadd_messages(messages))
- else:
- with self._make_sync_session() as session:
- for message in messages:
- session.add(self.converter.to_sql_model(message, self.session_id))
- session.commit()
+ # Add all messages in one transaction
+ with self._make_sync_session() as session:
+ for message in messages:
+ session.add(self.converter.to_sql_model(message, self.session_id))
+ session.commit()
 
  async def aadd_messages(self, messages: Sequence[BaseMessage]) -> None:
  # Add all messages in one transaction

libs/core/langchain_core/runnables/history.py

@@ -16,6 +16,7 @@
 from langchain_core.chat_history import BaseChatMessageHistory
 from langchain_core.load.load import load
 from langchain_core.pydantic_v1 import BaseModel
+from langchain_core.runnables import RunnableBranch
 from langchain_core.runnables.base import Runnable, RunnableBindingBase, RunnableLambda
 from langchain_core.runnables.passthrough import RunnablePassthrough
 from langchain_core.runnables.utils import (
@@ -306,8 +307,17 @@ def get_session_history(
  history_chain = RunnablePassthrough.assign(
  **{messages_key: history_chain}
  ).with_config(run_name="insert_history")
- bound = (
- history_chain | runnable.with_listeners(on_end=self._exit_history)
+ bound: Runnable = (
+ history_chain
+ | RunnableBranch(
+ (
+ RunnableLambda(
+ self._is_not_async, afunc=self._is_async
+ ).with_config(run_name="RunnableWithMessageHistoryInAsyncMode"),
+ runnable.with_alisteners(on_end=self._aexit_history),
+ ),
+ runnable.with_listeners(on_end=self._exit_history),
+ )
  ).with_config(run_name="RunnableWithMessageHistory")
 
  if history_factory_config:
@@ -367,6 +377,12 @@ def get_input_schema(
  else:
  return super_schema
 
+ def _is_not_async(self, *args: Sequence[Any], **kwargs: Dict[str, Any]) -> bool:
+ return False
+
+ async def _is_async(self, *args: Sequence[Any], **kwargs: Dict[str, Any]) -> bool:
+ return True
+
  def _get_input_messages(
  self, input_val: Union[str, BaseMessage, Sequence[BaseMessage], dict]
  ) -> List[BaseMessage]:
@@ -483,6 +499,23 @@ def _exit_history(self, run: Run, config: RunnableConfig) -> None:
  output_messages = self._get_output_messages(output_val)
  hist.add_messages(input_messages + output_messages)
 
+ async def _aexit_history(self, run: Run, config: RunnableConfig) -> None:
+ hist: BaseChatMessageHistory = config["configurable"]["message_history"]
+
+ # Get the input messages
+ inputs = load(run.inputs)
+ input_messages = self._get_input_messages(inputs)
+ # If historic messages were prepended to the input messages, remove them to
+ # avoid adding duplicate messages to history.
+ if not self.history_messages_key:
+ historic_messages = config["configurable"]["message_history"].messages
+ input_messages = input_messages[len(historic_messages) :]
+
+ # Get the output messages
+ output_val = load(run.outputs)
+ output_messages = self._get_output_messages(output_val)
+ await hist.aadd_messages(input_messages + output_messages)
+
  def _merge_configs(self, *configs: Optional[RunnableConfig]) -> RunnableConfig:
  config = super()._merge_configs(*configs)
  expected_keys = [field_spec.id for field_spec in self.history_factory_config]