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community[patch]: history size support for DynamoDBChatMessageHistory (#16794)

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**Description:** PR adds support for limiting number of messages
preserved in a session history for DynamoDBChatMessageHistory

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>
This commit is contained in:
Luka Krapic 2024-03-29 19:56:21 +01:00 committed by GitHub
parent 6dbf1a2de0
commit 727a2ea9f1
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1 changed files with 7 additions and 0 deletions
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7
libs/community/langchain_community/chat_message_histories/dynamodb.py
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@ -43,6 +43,8 @@ class DynamoDBChatMessageHistory(BaseChatMessageHistory):
table. DynamoDB handles deletion of expired items without consuming
write throughput. To enable this feature on the table, follow the
[AWS DynamoDB documentation](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/time-to-live-ttl-how-to.html)
history_size: Maximum number of messages to store. If None then there is no
limit. If not None then only the latest `history_size` messages are stored.
"""
def __init__(
@ -56,6 +58,7 @@ class DynamoDBChatMessageHistory(BaseChatMessageHistory):
kms_key_id: Optional[str] = None,
ttl: Optional[int] = None,
ttl_key_name: str = "expireAt",
history_size: Optional[int] = None,
):
if boto3_session:
client = boto3_session.resource("dynamodb", endpoint_url=endpoint_url)
@ -75,6 +78,7 @@ class DynamoDBChatMessageHistory(BaseChatMessageHistory):
self.key: Dict = key or {primary_key_name: session_id}
self.ttl = ttl
self.ttl_key_name = ttl_key_name
self.history_size = history_size
if kms_key_id:
try:
@ -149,6 +153,9 @@ class DynamoDBChatMessageHistory(BaseChatMessageHistory):
_message = message_to_dict(message)
messages.append(_message)
if self.history_size:
messages = messages[-self.history_size :]
try:
if self.ttl:
import time