Move arrpc server into a worker thread to reduce stutters (#1053)

Co-authored-by: V <vendicated@riseup.net>

scripts/build/build.mts

@@ -58,6 +58,12 @@ await Promise.all([
         outfile: "dist/js/main.js",
         footer: { js: "//# sourceURL=VCDMain" }
     }),
+    createContext({
+        ...NodeCommonOpts,
+        entryPoints: ["src/main/arrpc/worker.ts"],
+        outfile: "dist/js/arRpcWorker.js",
+        footer: { js: "//# sourceURL=VCDArRpcWorker" }
+    }),
     createContext({
         ...NodeCommonOpts,
         entryPoints: ["src/preload/index.ts"],

src/main/arrpc.ts

@@ -1,37 +0,0 @@
-/*
- * Vesktop, a desktop app aiming to give you a snappier Discord Experience
- * Copyright (c) 2023 Vendicated and Vencord contributors
- * SPDX-License-Identifier: GPL-3.0-or-later
- */
-
-import Server from "arrpc";
-import { IpcCommands } from "shared/IpcEvents";
-
-import { sendRendererCommand } from "./ipcCommands";
-import { Settings } from "./settings";
-
-let server: any;
-
-const inviteCodeRegex = /^(\w|-)+$/;
-
-export async function initArRPC() {
-    if (server || !Settings.store.arRPC) return;
-
-    try {
-        server = await new Server();
-        server.on("activity", (data: any) => sendRendererCommand(IpcCommands.RPC_ACTIVITY, JSON.stringify(data)));
-        server.on("invite", async (invite: string, callback: (valid: boolean) => void) => {
-            invite = String(invite);
-            if (!inviteCodeRegex.test(invite)) return callback(false);
-
-            await sendRendererCommand(IpcCommands.RPC_INVITE, invite).then(callback);
-        });
-        server.on("link", async (data: any, deepCallback: (valid: boolean) => void) => {
-            await sendRendererCommand(IpcCommands.RPC_DEEP_LINK, data).then(deepCallback);
-        });
-    } catch (e) {
-        console.error("Failed to start arRPC server", e);
-    }
-}
-
-Settings.addChangeListener("arRPC", initArRPC);

src/main/arrpc/index.ts

@@ -0,0 +1,83 @@
+/*
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2023 Vendicated and Vencord contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+import { resolve } from "path";
+import { IpcCommands } from "shared/IpcEvents";
+import { MessageChannel, Worker } from "worker_threads";
+
+import { sendRendererCommand } from "../ipcCommands";
+import { Settings } from "../settings";
+import { ArRpcEvent, ArRpcHostEvent } from "./types";
+
+let worker: Worker;
+
+const inviteCodeRegex = /^(\w|-)+$/;
+
+export async function initArRPC() {
+    if (worker || !Settings.store.arRPC) return;
+
+    try {
+        const { port1: hostPort, port2: workerPort } = new MessageChannel();
+
+        worker = new Worker(resolve(__dirname, "./arRpcWorker.js"), {
+            workerData: {
+                workerPort
+            },
+            transferList: [workerPort]
+        });
+
+        hostPort.on("message", async (e: ArRpcEvent) => {
+            switch (e.type) {
+                case "activity": {
+                    sendRendererCommand(IpcCommands.RPC_ACTIVITY, e.data);
+                    break;
+                }
+
+                case "invite": {
+                    const invite = String(e.data);
+
+                    const response: ArRpcHostEvent = {
+                        type: "ack-invite",
+                        nonce: e.nonce,
+                        data: false
+                    };
+
+                    if (!inviteCodeRegex.test(invite)) {
+                        return hostPort.postMessage(response);
+                    }
+
+                    response.data = await sendRendererCommand(IpcCommands.RPC_INVITE, invite).catch(() => false);
+
+                    hostPort.postMessage(response);
+                    break;
+                }
+
+                case "link": {
+                    const link = String(e.data);
+
+                    const response: ArRpcHostEvent = {
+                        type: "ack-link",
+                        nonce: e.nonce,
+                        data: false
+                    };
+
+                    if (!inviteCodeRegex.test(link)) {
+                        return hostPort.postMessage(response);
+                    }
+
+                    response.data = await sendRendererCommand(IpcCommands.RPC_DEEP_LINK, link).catch(() => false);
+
+                    hostPort.postMessage(response);
+                    break;
+                }
+            }
+        });
+    } catch (e) {
+        console.error("Failed to start arRPC server", e);
+    }
+}
+
+Settings.addChangeListener("arRPC", initArRPC);

src/main/arrpc/types.ts

@@ -0,0 +1,37 @@
+/*
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2025 Vendicated and Vesktop contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+export type ArRpcEvent = ArRpcActivityEvent | ArRpcInviteEvent | ArRpcLinkEvent;
+export type ArRpcHostEvent = ArRpcHostAckInviteEvent | ArRpcHostAckLinkEvent;
+
+export interface ArRpcActivityEvent {
+    type: "activity";
+    data: string;
+}
+
+export interface ArRpcInviteEvent {
+    type: "invite";
+    nonce: string;
+    data: string;
+}
+
+export interface ArRpcLinkEvent {
+    type: "link";
+    nonce: string;
+    data: string;
+}
+
+export interface ArRpcHostAckInviteEvent {
+    type: "ack-invite";
+    nonce: string;
+    data: boolean;
+}
+
+export interface ArRpcHostAckLinkEvent {
+    type: "ack-link";
+    nonce: string;
+    data: boolean;
+}

src/main/arrpc/worker.ts

@@ -0,0 +1,60 @@
+/*
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2025 Vendicated and Vesktop contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+import Server from "arrpc";
+import { randomUUID } from "crypto";
+import { MessagePort, workerData } from "worker_threads";
+
+import { ArRpcEvent, ArRpcHostEvent } from "./types";
+
+let server: any;
+
+type InviteCallback = (valid: boolean) => void;
+type LinkCallback = InviteCallback;
+
+const inviteCallbacks = new Map<string, InviteCallback>();
+const linkCallbacks = new Map<string, LinkCallback>();
+
+(async function () {
+    const { workerPort } = workerData as { workerPort: MessagePort };
+
+    server = await new Server();
+
+    server.on("activity", (data: any) => {
+        const event: ArRpcEvent = {
+            type: "activity",
+            data: JSON.stringify(data)
+        };
+        workerPort.postMessage(event);
+    });
+
+    server.on("invite", (invite: string, callback: InviteCallback) => {
+        const nonce = randomUUID();
+        inviteCallbacks.set(nonce, callback);
+
+        const event: ArRpcEvent = {
+            type: "invite",
+            data: invite,
+            nonce
+        };
+        workerPort.postMessage(event);
+    });
+
+    workerPort.on("message", (e: ArRpcHostEvent) => {
+        switch (e.type) {
+            case "ack-invite": {
+                inviteCallbacks.get(e.nonce)?.(e.data);
+                inviteCallbacks.delete(e.nonce);
+                break;
+            }
+            case "ack-link": {
+                linkCallbacks.get(e.nonce)?.(e.data);
+                linkCallbacks.delete(e.nonce);
+                break;
+            }
+        }
+    });
+})();

src/shared/IpcEvents.ts

@@ -49,8 +49,6 @@ export const enum IpcEvents {
     VIRT_MIC_START_SYSTEM = "VCD_VIRT_MIC_START_ALL",
     VIRT_MIC_STOP = "VCD_VIRT_MIC_STOP",
 
-    ARRPC_ACTIVITY = "VCD_ARRPC_ACTIVITY",
-
     CLIPBOARD_COPY_IMAGE = "VCD_CLIPBOARD_COPY_IMAGE",
 
     DEBUG_LAUNCH_GPU = "VCD_DEBUG_LAUNCH_GPU",