perf(OpenAI Node): Use streaming for file operations (#18666)

packages/@n8n/nodes-langchain/nodes/vendors/OpenAi/helpers/binary-data.ts

@@ -0,0 +1,27 @@
+import type { IExecuteFunctions } from 'n8n-workflow';
+
+/** Chunk size to use for streaming. 256Kb */
+const CHUNK_SIZE = 256 * 1024;
+
+/**
+ * Gets the binary data file for the given item index and given property name.
+ * Returns the file name, content type and the file content. Uses streaming
+ * when possible.
+ */
+export async function getBinaryDataFile(
+	ctx: IExecuteFunctions,
+	itemIdx: number,
+	binaryPropertyName: string,
+) {
+	const binaryData = ctx.helpers.assertBinaryData(itemIdx, binaryPropertyName);
+
+	const fileContent = binaryData.id
+		? await ctx.helpers.getBinaryStream(binaryData.id, CHUNK_SIZE)
+		: await ctx.helpers.getBinaryDataBuffer(itemIdx, binaryPropertyName);
+
+	return {
+		filename: binaryData.fileName,
+		contentType: binaryData.mimeType,
+		fileContent,
+	};
+}