community[minor]: Add async methods to CassandraChatMessageHistory (#21975)

libs/community/langchain_community/chat_message_histories/cassandra.py

@@ -3,10 +3,13 @@ from __future__ import annotations
 
 import json
 import uuid
-from typing import TYPE_CHECKING, List, Optional
+from typing import TYPE_CHECKING, Any, Dict, Iterable, List, Optional, Sequence
+
+from langchain_community.utilities.cassandra import SetupMode
 
 if TYPE_CHECKING:
     from cassandra.cluster import Session
+    from cassio.table.table_types import RowType
 
 from langchain_core.chat_history import BaseChatMessageHistory
 from langchain_core.messages import (
@@ -19,19 +22,14 @@ DEFAULT_TABLE_NAME = "message_store"
 DEFAULT_TTL_SECONDS = None
 
 
+def _rows_to_messages(rows: Iterable[RowType]) -> List[BaseMessage]:
+    message_blobs = [row["body_blob"] for row in rows][::-1]
+    items = [json.loads(message_blob) for message_blob in message_blobs]
+    messages = messages_from_dict(items)
+    return messages
+
+
 class CassandraChatMessageHistory(BaseChatMessageHistory):
-    """Chat message history that stores history in Cassandra.
-
-    Args:
-        session_id: arbitrary key that is used to store the messages
-            of a single chat session.
-        session: Cassandra driver session. If not provided, it is resolved from cassio.
-        keyspace: Cassandra key space. If not provided, it is resolved from cassio.
-        table_name: name of the table to use.
-        ttl_seconds: time-to-live (seconds) for automatic expiration
-            of stored entries. None (default) for no expiration.
-    """
-
     def __init__(
         self,
         session_id: str,
@@ -39,7 +37,22 @@ class CassandraChatMessageHistory(BaseChatMessageHistory):
         keyspace: Optional[str] = None,
         table_name: str = DEFAULT_TABLE_NAME,
         ttl_seconds: Optional[int] = DEFAULT_TTL_SECONDS,
+        *,
+        setup_mode: SetupMode = SetupMode.SYNC,
     ) -> None:
+        """Chat message history that stores history in Cassandra.
+
+        Args:
+            session_id: arbitrary key that is used to store the messages
+                of a single chat session.
+            session: Cassandra driver session.
+                If not provided, it is resolved from cassio.
+            keyspace: Cassandra key space. If not provided, it is resolved from cassio.
+            table_name: name of the table to use.
+            ttl_seconds: time-to-live (seconds) for automatic expiration
+                of stored entries. None (default) for no expiration.
+            setup_mode: mode used to create the Cassandra table (SYNC, ASYNC or OFF).
+        """
         try:
             from cassio.table import ClusteredCassandraTable
         except (ImportError, ModuleNotFoundError):
@@ -49,6 +62,9 @@ class CassandraChatMessageHistory(BaseChatMessageHistory):
             )
         self.session_id = session_id
         self.ttl_seconds = ttl_seconds
+        kwargs: Dict[str, Any] = {}
+        if setup_mode == SetupMode.ASYNC:
+            kwargs["async_setup"] = True
         self.table = ClusteredCassandraTable(
             session=session,
             keyspace=keyspace,
@@ -56,21 +72,26 @@ class CassandraChatMessageHistory(BaseChatMessageHistory):
             ttl_seconds=ttl_seconds,
             primary_key_type=["TEXT", "TIMEUUID"],
             ordering_in_partition="DESC",
+            skip_provisioning=setup_mode == SetupMode.OFF,
+            **kwargs,
         )
 
     @property
     def messages(self) -> List[BaseMessage]:  # type: ignore
         """Retrieve all session messages from DB"""
         # The latest are returned, in chronological order
-        message_blobs = [
-            row["body_blob"]
-            for row in self.table.get_partition(
-                partition_id=self.session_id,
-            )
-        ][::-1]
-        items = [json.loads(message_blob) for message_blob in message_blobs]
-        messages = messages_from_dict(items)
-        return messages
+        rows = self.table.get_partition(
+            partition_id=self.session_id,
+        )
+        return _rows_to_messages(rows)
+
+    async def aget_messages(self) -> List[BaseMessage]:
+        """Retrieve all session messages from DB"""
+        # The latest are returned, in chronological order
+        rows = await self.table.aget_partition(
+            partition_id=self.session_id,
+        )
+        return _rows_to_messages(rows)
 
     def add_message(self, message: BaseMessage) -> None:
         """Write a message to the table
@@ -86,6 +107,20 @@ class CassandraChatMessageHistory(BaseChatMessageHistory):
             ttl_seconds=self.ttl_seconds,
         )
 
+    async def aadd_messages(self, messages: Sequence[BaseMessage]) -> None:
+        for message in messages:
+            this_row_id = uuid.uuid1()
+            await self.table.aput(
+                partition_id=self.session_id,
+                row_id=this_row_id,
+                body_blob=json.dumps(message_to_dict(message)),
+                ttl_seconds=self.ttl_seconds,
+            )
+
     def clear(self) -> None:
         """Clear session memory from DB"""
         self.table.delete_partition(self.session_id)
+
+    async def aclear(self) -> None:
+        """Clear session memory from DB"""
+        await self.table.adelete_partition(self.session_id)

libs/community/tests/integration_tests/memory/test_memory_cassandra.py

@@ -1,6 +1,6 @@
 import os
 import time
-from typing import Optional
+from typing import Any, Optional
 
 from langchain.memory import ConversationBufferMemory
 from langchain_core.messages import AIMessage, HumanMessage
@@ -37,13 +37,15 @@ def _chat_message_history(
     # drop table if required
     if drop:
         session.execute(f"DROP TABLE IF EXISTS {keyspace}.{table_name}")
-    #
+
+    kwargs: Any = {} if ttl_seconds is None else {"ttl_seconds": ttl_seconds}
+
     return CassandraChatMessageHistory(
         session_id=session_id,
         session=session,
         keyspace=keyspace,
         table_name=table_name,
-        **({} if ttl_seconds is None else {"ttl_seconds": ttl_seconds}),
+        **kwargs,
     )