From b4b4fce55995563119cd2547d7ac04da24733359 Mon Sep 17 00:00:00 2001
From: Stefan Dirix <sdirix@eclipsesource.com>
Date: Wed, 27 Sep 2023 16:25:31 +0200
Subject: [PATCH] fix: restore src-gen frontend production behavior

Restores the usage of 'require' in production mode when loading
included modules.

At the moment, both in development as well as in production mode, the
frontend will be generated using the 'import' function. Webpack will
use this opportunity for code splitting, leading to the generation of
many small bundles. As they are sequentially loaded, this has a
negative effect on the startup speed of the frontend.

By using 'require' instead, wepack will produce a single bundle, which
is faster to transmit without additional roundtrips. This behavior was
used for production mode in all previous Theia versions and is now
restored.

Contributed on behalf of STMicroelectronics
---
 CHANGELOG.md                                       |  1 +
 .../src/generator/frontend-generator.ts            | 14 +++++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4940d003374e8..bd0d3a75e9c1b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 ## v1.42.0
 
 - [core] fixed logger level propagation when log config file changes at runtime [#12566](https://github.com/eclipse-theia/theia/pull/12566) - Contributed on behalf of STMicroelectronics
+- [dev-packages] restore src-gen frontend production behavior [12950](https://github.com/eclipse-theia/theia/pull/12950) - Contributed on behalf of STMicroelectronics
 - [vscode] stub TestController invalidateTestResults [#12944](https://github.com/eclipse-theia/theia/pull/12944) - Contributed by STMicroelectronics
 - [vscode] support iconPath in QuickPickItem [#12945](https://github.com/eclipse-theia/theia/pull/12945) - Contributed by STMicroelectronics
 - [vsx-registry] added a hint to extension fetching ENOTFOUND errors [#12858](https://github.com/eclipse-theia/theia/pull/12858) - Contributed by STMicroelectronics
diff --git a/dev-packages/application-manager/src/generator/frontend-generator.ts b/dev-packages/application-manager/src/generator/frontend-generator.ts
index 59cccab6e37b7..2155fdb31b36a 100644
--- a/dev-packages/application-manager/src/generator/frontend-generator.ts
+++ b/dev-packages/application-manager/src/generator/frontend-generator.ts
@@ -97,7 +97,7 @@ async function preload(parent) {
     container.parent = parent;
     try {
 ${Array.from(frontendPreloadModules.values(), jsModulePath => `\
-        await load(container, import('${jsModulePath}'));`).join(EOL)}
+        await load(container, ${this.importOrRequire()}('${jsModulePath}'));`).join(EOL)}
         const { Preloader } = require('@theia/core/lib/browser/preload/preloader');
         const preloader = container.get(Preloader);
         await preloader.initialize();
@@ -111,8 +111,8 @@ ${Array.from(frontendPreloadModules.values(), jsModulePath => `\
 
 module.exports = (async () => {
     const { messagingFrontendModule } = require('@theia/core/lib/${this.pck.isBrowser()
-            ? 'browser/messaging/messaging-frontend-module'
-            : 'electron-browser/messaging/electron-messaging-frontend-module'}');
+                ? 'browser/messaging/messaging-frontend-module'
+                : 'electron-browser/messaging/electron-messaging-frontend-module'}');
     const container = new Container();
     container.load(messagingFrontendModule);
     await preload(container);
@@ -125,9 +125,9 @@ module.exports = (async () => {
 
     try {
 ${Array.from(frontendModules.values(), jsModulePath => `\
-        await load(container, import('${jsModulePath}'));`).join(EOL)}
+        await load(container, ${this.importOrRequire()}('${jsModulePath}'));`).join(EOL)}
         await start();
-    } catch (reason) {
+    } catch (reason) {i
         console.error('Failed to start the frontend application.');
         if (reason) {
             console.error(reason);
@@ -142,6 +142,10 @@ ${Array.from(frontendModules.values(), jsModulePath => `\
 `;
     }
 
+    protected importOrRequire(): string {
+        return this.options.mode !== 'production' ? 'import' : 'require';
+    }
+
     /** HTML for secondary windows that contain an extracted widget. */
     protected compileSecondaryWindowHtml(): string {
         return `<!DOCTYPE html>