From 963b8ec82f44bb4b83ad0ff678420a15d6d21072 Mon Sep 17 00:00:00 2001
From: Bart <bartolomej.kozorog@gmail.com>
Date: Tue, 20 Sep 2022 16:39:11 +0200
Subject: [PATCH] start backend in seperate worker thread

---
 backend/src/projects/projects.service.ts |  3 +-
 frontend/src/targets/electron/main.ts    | 31 ++++-----------
 frontend/src/targets/electron/worker.ts  | 49 ++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 26 deletions(-)
 create mode 100644 frontend/src/targets/electron/worker.ts

diff --git a/backend/src/projects/projects.service.ts b/backend/src/projects/projects.service.ts
index cfa1790a..e14e122a 100644
--- a/backend/src/projects/projects.service.ts
+++ b/backend/src/projects/projects.service.ts
@@ -119,8 +119,7 @@ export class ProjectsService {
 
   async cleanupProject() {
     try {
-      // remove all existing data of previously used project
-      // TODO(milestone-x): persist data for projects by default?
+      // Remove all cached data of previously used project
       await this.commonService.removeBlockchainData();
     } catch (e) {
       throw new InternalServerErrorException("Database cleanup failed");
diff --git a/frontend/src/targets/electron/main.ts b/frontend/src/targets/electron/main.ts
index ca98eed5..addf92cd 100644
--- a/frontend/src/targets/electron/main.ts
+++ b/frontend/src/targets/electron/main.ts
@@ -1,33 +1,14 @@
 import * as path from "path";
 import { app, BrowserWindow, shell, dialog } from "electron";
-import { createApp, ProcessManagerService } from "@flowser/backend";
+import { ProcessManagerService } from "@flowser/backend";
 import fixPath from "fix-path";
-import { INestApplication } from "@nestjs/common";
+import * as worker from "./worker";
 
 fixPath();
 
 const minWidth = 900;
 const minHeight = 600;
 
-let backend: INestApplication;
-
-async function startBackend() {
-  const userDataPath = app.getPath("userData");
-  const databaseFilePath = path.join(userDataPath, "flowser.sqlite");
-  if (backend) {
-    await backend.close();
-  }
-  backend = await createApp({
-    database: {
-      type: "sqlite",
-      name: databaseFilePath,
-    },
-    common: {
-      httpServerPort: 6061,
-    },
-  });
-}
-
 async function createWindow() {
   const win = new BrowserWindow({
     width: minWidth,
@@ -54,7 +35,7 @@ async function createWindow() {
 
   async function handleStart() {
     try {
-      await startBackend();
+      await worker.start();
     } catch (error) {
       await handleBackendError({
         error,
@@ -87,8 +68,10 @@ app.on("activate", function () {
 
 app.on("will-quit", async function () {
   // Make sure to stop all child processes, so that they don't become orphans
-  const processManagerService = backend.get(ProcessManagerService);
-  await processManagerService.stopAll();
+  if (worker.backend) {
+    const processManagerService = worker.backend.get(ProcessManagerService);
+    await processManagerService.stopAll();
+  }
 });
 
 type ErrorWithCode = { code: string };
diff --git a/frontend/src/targets/electron/worker.ts b/frontend/src/targets/electron/worker.ts
new file mode 100644
index 00000000..fe7e8fc4
--- /dev/null
+++ b/frontend/src/targets/electron/worker.ts
@@ -0,0 +1,49 @@
+import { Worker, isMainThread, parentPort, workerData } from "worker_threads";
+import path from "path";
+import { app } from "electron";
+import { createApp } from "@flowser/backend";
+import { INestApplication } from "@nestjs/common";
+
+export let backend: INestApplication;
+
+async function startBackend({ userDataPath }: { userDataPath: string }) {
+  const databaseFilePath = path.join(userDataPath, "flowser.sqlite");
+  if (backend) {
+    await backend.close();
+  }
+  backend = await createApp({
+    database: {
+      type: "sqlite",
+      name: databaseFilePath,
+    },
+    common: {
+      httpServerPort: 6061,
+    },
+  });
+}
+
+export let start: () => Promise<unknown>;
+
+if (isMainThread) {
+  start = async function () {
+    const userDataPath = app.getPath("userData");
+    return new Promise((resolve, reject) => {
+      const worker = new Worker(__filename, {
+        workerData: {
+          userDataPath,
+        },
+      });
+      worker.on("message", resolve);
+      worker.on("error", reject);
+      worker.on("exit", (code) => {
+        if (code !== 0)
+          reject(new Error(`Worker stopped with exit code ${code}`));
+      });
+    });
+  };
+} else {
+  const { userDataPath } = workerData;
+  startBackend({
+    userDataPath,
+  }).then(() => parentPort?.postMessage("Backend started"));
+}