⚡ Bolt: [performance improvement] Optimize readFileSync encoding

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2024-05-24 - readFileSync toString buffer allocation bypass
+**Learning:** In standard Node.js applications, omitting the encoding parameter on `readFileSync` reads the file as a raw `Buffer`. If the immediate next operation is `.toString()`, this incurs an extra, temporary memory allocation for the intermediate buffer object that is then garbage collected. This is a common but subtle memory overhead pattern.
+**Action:** Always prefer `readFileSync(path, 'utf8')` over `readFileSync(path).toString()` to directly create the string from the C++ layer and skip intermediate buffer allocations.

packages/@expo/cli/src/utils/mergeGitIgnorePaths.ts

@@ -35,8 +35,8 @@ export function mergeGitIgnorePaths(
     return null;
   }
 
-  const targetGitIgnore = fs.readFileSync(targetGitIgnorePath).toString();
-  const sourceGitIgnore = fs.readFileSync(sourceGitIgnorePath).toString();
+  const targetGitIgnore = fs.readFileSync(targetGitIgnorePath, 'utf8');
+  const sourceGitIgnore = fs.readFileSync(sourceGitIgnorePath, 'utf8');
   const merged = mergeGitIgnoreContents(targetGitIgnore, sourceGitIgnore);
   // Only rewrite the file if it was modified.
   if (merged.contents) {

packages/@expo/config-plugins/src/android/Package.ts

@@ -125,7 +125,7 @@ export async function renameJniOnDiskForType({
   filesToUpdate.forEach((filepath: string) => {
     try {
       if (fs.lstatSync(filepath).isFile() && ['.h', '.cpp'].includes(path.extname(filepath))) {
-        let contents = fs.readFileSync(filepath).toString();
+        let contents = fs.readFileSync(filepath, 'utf8');
         contents = contents.replace(
           new RegExp(transformJavaClassDescriptor(currentPackageName).replace(/\//g, '\\/'), 'g'),
           transformJavaClassDescriptor(packageName)
@@ -207,7 +207,7 @@ export async function renamePackageOnDiskForType({
   filesToUpdate.forEach((filepath: string) => {
     try {
       if (fs.lstatSync(filepath).isFile()) {
-        let contents = fs.readFileSync(filepath).toString();
+        let contents = fs.readFileSync(filepath, 'utf8');
         if (path.extname(filepath) === '.kt') {
           contents = replacePackageName(contents, currentPackageName, kotlinSanitizedPackageName);
         } else {

packages/expo-brownfield/plugin/src/common/filesystem.ts

@@ -26,13 +26,14 @@ const maybeReadOverwrittenTemplate = (template: string, platform?: PlatformStrin
   try {
     accessSync(path.join(process.cwd(), '.brownfield-templates'));
     if (existsSync(path.join(process.cwd(), '.brownfield-templates', template))) {
-      return readFileSync(path.join(process.cwd(), '.brownfield-templates', template)).toString();
+      return readFileSync(path.join(process.cwd(), '.brownfield-templates', template), 'utf8');
     }
 
     if (existsSync(path.join(process.cwd(), '.brownfield-templates', platform ?? '.', template))) {
       return readFileSync(
-        path.join(process.cwd(), '.brownfield-templates', platform ?? '.', template)
-      ).toString();
+        path.join(process.cwd(), '.brownfield-templates', platform ?? '.', template),
+        'utf8'
+      );
     }
     // eslint-disable-next-line no-empty
   } catch {}
@@ -55,7 +56,7 @@ const readTemplate = (template: string, platform?: PlatformString): string => {
     throw new Error(`Template ${template} doesn't exist at ${templatePath}`);
   }
 
-  return readFileSync(templatePath).toString();
+  return readFileSync(templatePath, 'utf8');
 };
 
 const createFileFromTemplateInternal = (

packages/pod-install/src/index.ts

@@ -41,7 +41,7 @@ async function runAsync(maybeProjectDirectory?: string): Promise<void> {
       process.exit(1);
     }
 
-    const jsonData = JSON.parse(readFileSync(packageJsonPath).toString());
+    const jsonData = JSON.parse(readFileSync(packageJsonPath, 'utf8'));
     const hasExpoPackage = jsonData.dependencies?.hasOwnProperty('expo');
 
     if (hasExpoPackage) {