first commit

packages/@n8n/nodes-langchain/nodes/memory/MemoryBufferWindow/MemoryBufferWindow.node.ts

@@ -0,0 +1,183 @@
+import type { BufferWindowMemoryInput } from '@langchain/classic/memory';
+import { BufferWindowMemory } from '@langchain/classic/memory';
+import {
+	NodeConnectionTypes,
+	type INodeType,
+	type INodeTypeDescription,
+	type ISupplyDataFunctions,
+	type SupplyData,
+} from 'n8n-workflow';
+
+import { getSessionId } from '@utils/helpers';
+import { logWrapper, getConnectionHintNoticeField } from '@n8n/ai-utilities';
+
+import {
+	sessionIdOption,
+	sessionKeyProperty,
+	contextWindowLengthProperty,
+	expressionSessionKeyProperty,
+} from '../descriptions';
+
+class MemoryChatBufferSingleton {
+	private static instance: MemoryChatBufferSingleton;
+
+	private memoryBuffer: Map<
+		string,
+		{ buffer: BufferWindowMemory; created: Date; last_accessed: Date }
+	>;
+
+	private constructor() {
+		this.memoryBuffer = new Map();
+	}
+
+	static getInstance(): MemoryChatBufferSingleton {
+		if (!MemoryChatBufferSingleton.instance) {
+			MemoryChatBufferSingleton.instance = new MemoryChatBufferSingleton();
+		}
+		return MemoryChatBufferSingleton.instance;
+	}
+
+	async getMemory(
+		sessionKey: string,
+		memoryParams: BufferWindowMemoryInput,
+	): Promise<BufferWindowMemory> {
+		await this.cleanupStaleBuffers();
+
+		let memoryInstance = this.memoryBuffer.get(sessionKey);
+		if (memoryInstance) {
+			memoryInstance.last_accessed = new Date();
+		} else {
+			const newMemory = new BufferWindowMemory(memoryParams);
+
+			memoryInstance = {
+				buffer: newMemory,
+				created: new Date(),
+				last_accessed: new Date(),
+			};
+			this.memoryBuffer.set(sessionKey, memoryInstance);
+		}
+		return memoryInstance.buffer;
+	}
+
+	private async cleanupStaleBuffers(): Promise<void> {
+		const oneHourAgo = new Date(Date.now() - 60 * 60 * 1000);
+
+		for (const [key, memoryInstance] of this.memoryBuffer.entries()) {
+			if (memoryInstance.last_accessed < oneHourAgo) {
+				await this.memoryBuffer.get(key)?.buffer.clear();
+				this.memoryBuffer.delete(key);
+			}
+		}
+	}
+}
+
+export class MemoryBufferWindow implements INodeType {
+	description: INodeTypeDescription = {
+		displayName: 'Simple Memory',
+		name: 'memoryBufferWindow',
+		icon: 'fa:database',
+		iconColor: 'black',
+		group: ['transform'],
+		version: [1, 1.1, 1.2, 1.3],
+		description: 'Stores in n8n memory, so no credentials required',
+		defaults: {
+			name: 'Simple Memory',
+		},
+		codex: {
+			categories: ['AI'],
+			subcategories: {
+				AI: ['Memory'],
+				Memory: ['For beginners'],
+			},
+			resources: {
+				primaryDocumentation: [
+					{
+						url: 'https://docs.n8n.io/integrations/builtin/cluster-nodes/sub-nodes/n8n-nodes-langchain.memorybufferwindow/',
+					},
+				],
+			},
+		},
+		builderHint: {
+			message:
+				'Reuse with multiple agents in the same workflow by connecting to multiple agent nodes so agents have a shared context.',
+		},
+
+		inputs: [],
+
+		outputs: [NodeConnectionTypes.AiMemory],
+		outputNames: ['Memory'],
+		properties: [
+			getConnectionHintNoticeField([NodeConnectionTypes.AiAgent]),
+			{
+				displayName:
+					'This node stores memory locally in the n8n instance. It is not compatible with Queue Mode or Multi-Main setups, as memory will not be shared across workers. For production use with scaling, consider using an external memory store such as Redis, Postgres, or another persistent memory node.',
+				name: 'scalingNotice',
+				type: 'notice',
+				default: '',
+			},
+			{
+				displayName: 'Session Key',
+				name: 'sessionKey',
+				type: 'string',
+				default: 'chat_history',
+				description: 'The key to use to store the memory in the workflow data',
+				displayOptions: {
+					show: {
+						'@version': [1],
+					},
+				},
+			},
+			{
+				displayName: 'Session ID',
+				name: 'sessionKey',
+				type: 'string',
+				default: '={{ $json.sessionId }}',
+				description: 'The key to use to store the memory',
+				displayOptions: {
+					show: {
+						'@version': [1.1],
+					},
+				},
+			},
+			{
+				...sessionIdOption,
+				displayOptions: {
+					show: {
+						'@version': [{ _cnd: { gte: 1.2 } }],
+					},
+				},
+			},
+			expressionSessionKeyProperty(1.3),
+			sessionKeyProperty,
+			contextWindowLengthProperty,
+		],
+	};
+
+	async supplyData(this: ISupplyDataFunctions, itemIndex: number): Promise<SupplyData> {
+		const contextWindowLength = this.getNodeParameter('contextWindowLength', itemIndex) as number;
+		const workflowId = this.getWorkflow().id;
+		const memoryInstance = MemoryChatBufferSingleton.getInstance();
+
+		const nodeVersion = this.getNode().typeVersion;
+
+		let sessionId;
+
+		if (nodeVersion >= 1.2) {
+			sessionId = getSessionId(this, itemIndex);
+		} else {
+			sessionId = this.getNodeParameter('sessionKey', itemIndex) as string;
+		}
+
+		const memory = await memoryInstance.getMemory(`${workflowId}__${sessionId}`, {
+			k: contextWindowLength,
+			inputKey: 'input',
+			memoryKey: 'chat_history',
+			outputKey: 'output',
+			returnMessages: true,
+		});
+
+		return {
+			response: logWrapper(memory, this),
+		};
+	}
+}