mirror of
https://github.com/hwchase17/langchain
synced 2024-11-10 01:10:59 +00:00
89 lines
2.8 KiB
Python
89 lines
2.8 KiB
Python
"""Cassandra-based chat message history, based on cassIO."""
|
|
from __future__ import annotations
|
|
|
|
import json
|
|
import typing
|
|
import uuid
|
|
from typing import List
|
|
|
|
if typing.TYPE_CHECKING:
|
|
from cassandra.cluster import Session
|
|
|
|
from langchain_core.chat_history import BaseChatMessageHistory
|
|
from langchain_core.messages import (
|
|
BaseMessage,
|
|
message_to_dict,
|
|
messages_from_dict,
|
|
)
|
|
|
|
DEFAULT_TABLE_NAME = "message_store"
|
|
DEFAULT_TTL_SECONDS = None
|
|
|
|
|
|
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: a Cassandra `Session` object (an open DB connection)
|
|
keyspace: name of the keyspace to use.
|
|
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,
|
|
session: Session,
|
|
keyspace: str,
|
|
table_name: str = DEFAULT_TABLE_NAME,
|
|
ttl_seconds: typing.Optional[int] = DEFAULT_TTL_SECONDS,
|
|
) -> None:
|
|
try:
|
|
from cassio.table import ClusteredCassandraTable
|
|
except (ImportError, ModuleNotFoundError):
|
|
raise ImportError(
|
|
"Could not import cassio python package. "
|
|
"Please install it with `pip install cassio`."
|
|
)
|
|
self.session_id = session_id
|
|
self.ttl_seconds = ttl_seconds
|
|
self.table = ClusteredCassandraTable(
|
|
session=session,
|
|
keyspace=keyspace,
|
|
table=table_name,
|
|
ttl_seconds=ttl_seconds,
|
|
primary_key_type=["TEXT", "TIMEUUID"],
|
|
ordering_in_partition="DESC",
|
|
)
|
|
|
|
@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
|
|
|
|
def add_message(self, message: BaseMessage) -> None:
|
|
"""Write a message to the table"""
|
|
this_row_id = uuid.uuid1()
|
|
self.table.put(
|
|
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)
|