From a2cbcf05191f98c501c6cf4c8a6636f8222115dc Mon Sep 17 00:00:00 2001
From: Andras Schmelczer <andras@schmelczer.dev>
Date: Sat, 16 Aug 2025 12:21:41 +0100
Subject: [PATCH] SLow down requests for development

---
 .../src/debugging/flaky-websocket-factory.ts  | 71 +++++++++++++++++++
 .../src/debugging/slow-fetch-factory.ts       | 14 ++++
 frontend/obsidian-plugin/src/utils/sleep.ts   |  3 +
 .../obsidian-plugin/src/vault-link-plugin.ts  | 11 +++
 4 files changed, 99 insertions(+)
 create mode 100644 frontend/obsidian-plugin/src/debugging/flaky-websocket-factory.ts
 create mode 100644 frontend/obsidian-plugin/src/debugging/slow-fetch-factory.ts
 create mode 100644 frontend/obsidian-plugin/src/utils/sleep.ts

diff --git a/frontend/obsidian-plugin/src/debugging/flaky-websocket-factory.ts b/frontend/obsidian-plugin/src/debugging/flaky-websocket-factory.ts
new file mode 100644
index 00000000..f2f3db0a
--- /dev/null
+++ b/frontend/obsidian-plugin/src/debugging/flaky-websocket-factory.ts
@@ -0,0 +1,71 @@
+import { helpers, Logger } from "sync-client";
+
+export function flakyWebSocketFactory(
+	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 helpers.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.waitForLock(FlakyWebSocket.RECEIVE_KEY);
+
+				if (jitterScaleInSeconds > 0) {
+					await sleep(Math.random() * jitterScaleInSeconds * 1000);
+				}
+
+				callback(event);
+
+				this.locks.unlock(FlakyWebSocket.RECEIVE_KEY);
+			};
+		}
+
+		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 async send(
+			data: string | ArrayBufferLike | Blob | ArrayBufferView
+		): Promise<void> {
+			// maintain message order
+			await this.locks.waitForLock(FlakyWebSocket.SEND_KEY);
+
+			if (jitterScaleInSeconds > 0) {
+				await sleep(Math.random() * jitterScaleInSeconds * 1000);
+			}
+
+			super.send(data);
+
+			this.locks.unlock(FlakyWebSocket.SEND_KEY);
+		}
+	} as unknown as typeof WebSocket;
+}
diff --git a/frontend/obsidian-plugin/src/debugging/slow-fetch-factory.ts b/frontend/obsidian-plugin/src/debugging/slow-fetch-factory.ts
new file mode 100644
index 00000000..5fe6c3ef
--- /dev/null
+++ b/frontend/obsidian-plugin/src/debugging/slow-fetch-factory.ts
@@ -0,0 +1,14 @@
+export const slowFetchFactory =
+	(jitterScaleInSeconds: number) =>
+	async (
+		input: string | URL | globalThis.Request,
+		init?: RequestInit
+	): Promise<Response> => {
+		if (jitterScaleInSeconds > 0) {
+			await sleep(Math.random() * jitterScaleInSeconds * 1000);
+		}
+
+		const response = await fetch(input, init);
+
+		return response;
+	};
diff --git a/frontend/obsidian-plugin/src/utils/sleep.ts b/frontend/obsidian-plugin/src/utils/sleep.ts
new file mode 100644
index 00000000..638fc019
--- /dev/null
+++ b/frontend/obsidian-plugin/src/utils/sleep.ts
@@ -0,0 +1,3 @@
+export async function sleep(ms: number): Promise<void> {
+	return new Promise((resolve) => setTimeout(resolve, ms));
+}
diff --git a/frontend/obsidian-plugin/src/vault-link-plugin.ts b/frontend/obsidian-plugin/src/vault-link-plugin.ts
index 6e8e4cf7..0f3e5fb8 100644
--- a/frontend/obsidian-plugin/src/vault-link-plugin.ts
+++ b/frontend/obsidian-plugin/src/vault-link-plugin.ts
@@ -22,6 +22,8 @@ import {
 	setCursors
 } from "./views/cursors/remote-cursors-plugin";
 import { LocalCursorUpdateListener } from "./views/cursors/local-cursor-update-listener";
+import { slowFetchFactory } from "./debugging/slow-fetch-factory";
+import { flakyWebSocketFactory } from "./debugging/flaky-websocket-factory";
 
 const MIN_WAIT_BETWEEN_UPDATES_IN_MS = 250;
 export default class VaultLinkPlugin extends Plugin {
@@ -41,6 +43,15 @@ export default class VaultLinkPlugin extends Plugin {
 			".trash/**"
 		);
 
+		const isDebugBuild = process.env.NODE_ENV === "development";
+
+		const debugOptions = isDebugBuild
+			? {
+					fetch: slowFetchFactory(1),
+					webSocket: flakyWebSocketFactory(1, new Logger())
+				}
+			: {};
+
 		this.client = await SyncClient.create({
 			fs: new ObsidianFileSystemOperations(
 				this.app.vault,