[Bootstrap] Add multi-instance handling

README.md

@@ -43,6 +43,7 @@ You can configure OpenAsar via `settings.json` (found in your Discord app data /
 - `quickstart` (bool, default false) - whether to use Quickstart (experimental)
 - `skipStartupUpdateChecks` (bool, default false) - skips startup update checking (Linux-only)
 - `autoupdate` (bool, default true) - whether to autoupdate OpenAsar after Discord startup
+- `multiInstance` (bool, default false) - whether to enable multi-instance
 
 An example of a settings.json with OpenAsar config:
 ```json

src/bootstrap.js

@@ -68,6 +68,8 @@ const startUpdate = () => {
   });
 };
 
+const hasArgvFlag = (flag) => (process.argv || []).slice(1).includes(flag);
+
 module.exports = () => {
   // Paths logging
   log('Paths', `Init! Returns:
@@ -77,6 +79,14 @@ getResources: ${paths.getResources()}
 getModuleDataPath: ${paths.getModuleDataPath()}
 getInstallPath: ${paths.getInstallPath()}`);
 
+  const instanceLock = app.requestSingleInstanceLock();
+  const allowMultiInstance = hasArgvFlag('--multi-instance') || oaConfig.multiInstance; // argv flag or config
+
+  if (!instanceLock && !allowMultiInstance) {
+    log('Bootstrap', 'Non-first instance, quitting (multi-instance disabled)');
+    return app.quit();
+  }
+
   if (app.isReady()) {
     startUpdate();
   } else {