Package dev.langchain4j.memory.chat

Class TokenWindowChatMemory

java.lang.Object

dev.langchain4j.memory.chat.TokenWindowChatMemory

All Implemented Interfaces:

ChatMemory

public class TokenWindowChatMemory
extends Object
implements ChatMemory

This chat memory operates as a sliding window of maxTokens tokens. It retains as many of the most recent messages as can fit into the window. If there isn't enough space for a new message, the oldest one (or multiple) is evicted. Messages are indivisible. If a message doesn't fit, it is evicted completely.

Once added, a SystemMessage is always retained. Only one SystemMessage can be held at a time. If a new SystemMessage with the same content is added, it is ignored. If a new SystemMessage with different content is added, the previous SystemMessage is removed.

If an AiMessage containing ToolExecutionRequest(s) is evicted, the following orphan ToolExecutionResultMessage(s) are also automatically evicted to avoid problems with some LLM providers (such as OpenAI) that prohibit sending orphan ToolExecutionResultMessage(s) in the request.

The state of chat memory is stored in ChatMemoryStore (InMemoryChatMemoryStore is used by default).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	TokenWindowChatMemory.Builder

Method Summary

Modifier and Type	Method	Description
void	add(ChatMessage message)	Adds a message to the chat memory.
static TokenWindowChatMemory.Builder	builder()
void	clear()	Clears the chat memory.
Object	id()	The ID of the ChatMemory.
List<ChatMessage>	messages()	Retrieves messages from the chat memory.
static TokenWindowChatMemory	withMaxTokens(int maxTokens, Tokenizer tokenizer)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

id

public Object id()

Description copied from interface: ChatMemory

The ID of the ChatMemory.

Specified by:

id in interface ChatMemory

Returns:

The ID of the ChatMemory.

add

public void add(ChatMessage message)

Description copied from interface: ChatMemory

Adds a message to the chat memory.

Specified by:

add in interface ChatMemory

Parameters:

message - The ChatMessage to add.

messages

public List<ChatMessage> messages()

Description copied from interface: ChatMemory

Retrieves messages from the chat memory. Depending on the implementation, it may not return all previously added messages, but rather a subset, a summary, or a combination thereof.

Specified by:

messages in interface ChatMemory

Returns:

A list of ChatMessage objects that represent the current state of the chat memory.

clear

public void clear()

Description copied from interface: ChatMemory

Clears the chat memory.

Specified by:

clear in interface ChatMemory

builder

public static TokenWindowChatMemory.Builder builder()

withMaxTokens

public static TokenWindowChatMemory withMaxTokens(int maxTokens,
 Tokenizer tokenizer)