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frontend/sync-client/src/debugging/slow-web-socket-factory.ts

@@ -0,0 +1,81 @@
+import { sleep } from "../utils/sleep";
+import { Locks } from "../utils/locks";
+import type { Logger } from "../tracing/logger";
+
+export function slowWebSocketFactory(
+	jitterScaleInSeconds: number,
+	logger: Logger
+): typeof WebSocket {
+	// eslint-disable-next-line
+	return class FlakyWebSocket extends WebSocket {
+		private static readonly RECEIVE_KEY = "websocket-receive";
+		private static readonly SEND_KEY = "websocket-send";
+
+		private readonly locks = new Locks(logger);
+
+		public set onopen(callback: (event: Event) => void) {
+			super.onopen = async (event: Event): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+
+				callback(event);
+			};
+		}
+
+		public set onmessage(callback: (event: MessageEvent) => void) {
+			super.onmessage = async (event: MessageEvent): Promise<void> => {
+				await this.locks.withLock(
+					FlakyWebSocket.RECEIVE_KEY,
+					async () => {
+						if (jitterScaleInSeconds > 0) {
+							await sleep(
+								Math.random() * jitterScaleInSeconds * 1000
+							);
+						}
+
+						callback(event);
+					}
+				);
+			};
+		}
+
+		public set onclose(callback: (event: CloseEvent) => void) {
+			super.onclose = async (event: CloseEvent): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+				callback(event);
+			};
+		}
+
+		public set onerror(callback: (event: Event) => void) {
+			super.onerror = async (event: Event): Promise<void> => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+				callback(event);
+			};
+		}
+
+		public send(
+			data: string | ArrayBufferLike | Blob | ArrayBufferView
+		): void {
+			this.waitingSend(data).catch((error: unknown) => {
+				logger.error(`Error sending WebSocket message: ${error}`);
+			});
+		}
+
+		private async waitingSend(
+			data: string | ArrayBufferLike | Blob | ArrayBufferView
+		): Promise<void> {
+			// maintain message order
+			await this.locks.withLock(FlakyWebSocket.SEND_KEY, async () => {
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+				super.send(data);
+			});
+		}
+	} as unknown as typeof WebSocket;
+}