[flutter_tools] skip copying 1GB of data from chrome cache dirs (#81170)

* [flutter_tools] skip copying 1GB of data from chrome cache dirs

* Update chrome.dart

packages/flutter_tools/lib/src/base/file_system.dart

@@ -107,10 +107,12 @@ String getDisplayPath(String fullPath, FileSystem fileSystem) {
 /// source/destination file pair.
 ///
 /// Skips files if [shouldCopyFile] returns `false`.
+/// Does not recurse over directories if [shouldCopyDirectory] returns `false`.
 void copyDirectory(
   Directory srcDir,
   Directory destDir, {
   bool Function(File srcFile, File destFile)? shouldCopyFile,
+  bool Function(Directory)? shouldCopyDirectory,
   void Function(File srcFile, File destFile)? onFileCopied,
 }) {
   if (!srcDir.existsSync()) {
@@ -134,6 +136,9 @@ void copyDirectory(
       newFile.writeAsBytesSync(entity.readAsBytesSync());
       onFileCopied?.call(entity, newFile);
     } else if (entity is Directory) {
+      if (shouldCopyDirectory != null && !shouldCopyDirectory(entity)) {
+        continue;
+      }
       copyDirectory(
         entity,
         destDir.fileSystem.directory(newPath),

packages/flutter_tools/lib/src/web/chrome.dart

@@ -318,13 +318,24 @@ class ChromiumLauncher {
   ///
   /// Note: more detailed docs of the Chrome user preferences store exists here:
   /// https://www.chromium.org/developers/design-documents/preferences.
+  ///
+  /// This intentionally skips the Cache, Code Cache, and GPUCache directories.
+  /// While we're not sure exactly what is in them, this constitutes nearly 1 GB
+  /// of data for a fresh flutter run and adds significant overhead to all startups.
+  /// For workflows that may require this data, using the start-paused flag and
+  /// dart debug extension with a user controlled browser profile will lead to a
+  /// better experience.
   void _cacheUserSessionInformation(Directory userDataDir, Directory cacheDir) {
     final Directory targetChromeDefault = _fileSystem.directory(_fileSystem.path.join(cacheDir.path, _chromeDefaultPath));
     final Directory sourceChromeDefault = _fileSystem.directory(_fileSystem.path.join(userDataDir.path, _chromeDefaultPath));
     if (sourceChromeDefault.existsSync()) {
       targetChromeDefault.createSync(recursive: true);
       try {
-        copyDirectory(sourceChromeDefault, targetChromeDefault);
+        copyDirectory(
+          sourceChromeDefault,
+          targetChromeDefault,
+          shouldCopyDirectory: _isNotCacheDirectory
+        );
       } on FileSystemException catch (err) {
         // This is a best-effort update. Display the message in case the failure is relevant.
         // one possible example is a file lock due to multiple running chrome instances.
@@ -352,13 +363,24 @@ class ChromiumLauncher {
     try {
       if (sourceChromeDefault.existsSync()) {
         targetChromeDefault.createSync(recursive: true);
-        copyDirectory(sourceChromeDefault, targetChromeDefault);
+        copyDirectory(
+          sourceChromeDefault,
+          targetChromeDefault,
+          shouldCopyDirectory: _isNotCacheDirectory,
+        );
       }
     } on FileSystemException catch (err) {
       _logger.printError('Failed to restore Chrome preferences: $err');
     }
   }
 
+  // Cache, Code Cache, and GPUCache are nearly 1GB of data
+  bool _isNotCacheDirectory(Directory directory) {
+    return !directory.path.endsWith('Cache') &&
+           !directory.path.endsWith('Code Cache') &&
+           !directory.path.endsWith('GPUCache');
+  }
+
   Future<Chromium> _connect(Chromium chrome, bool skipCheck) async {
     // The connection is lazy. Try a simple call to make sure the provided
     // connection is valid.

packages/flutter_tools/test/general.shard/base/file_system_test.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:io' as io;
 
 import 'package:file/memory.dart';
+import 'package:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/platform.dart';
@@ -99,6 +100,25 @@ void main() {
       expect(destination.childFile('a.txt').existsSync(), isFalse);
       expect(destination.childDirectory('nested').childFile('a.txt').existsSync(), isFalse);
     });
+
+    testWithoutContext('Skip directories if shouldCopyDirectory returns false', () {
+      final MemoryFileSystem fileSystem = MemoryFileSystem.test();
+      final Directory origin = fileSystem.directory('/origin');
+      origin.createSync();
+      fileSystem.file(fileSystem.path.join('origin', 'a.txt')).writeAsStringSync('irrelevant');
+      fileSystem.directory('/origin/nested').createSync();
+      fileSystem.file(fileSystem.path.join('origin', 'nested', 'a.txt')).writeAsStringSync('irrelevant');
+      fileSystem.file(fileSystem.path.join('origin', 'nested', 'b.txt')).writeAsStringSync('irrelevant');
+
+      final Directory destination = fileSystem.directory('/destination');
+      copyDirectory(origin, destination, shouldCopyDirectory: (Directory directory) {
+        return !directory.path.endsWith('nested');
+      });
+
+      expect(destination, exists);
+      expect(destination.childDirectory('nested'), isNot(exists));
+      expect(destination.childDirectory('nested').childFile('b.txt'),isNot(exists));
+    });
   });
 
   group('escapePath', () {

packages/flutter_tools/test/general.shard/web/chrome_test.dart

@@ -5,6 +5,7 @@
 import 'dart:async';
 
 import 'package:file/memory.dart';
+import 'package:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/os.dart';
@@ -26,6 +27,12 @@ const List<String> kChromeArgs = <String>[
   '--disable-translate',
 ];
 
+const List<String> kCodeCache = <String>[
+  'Cache',
+  'Code Cache',
+  'GPUCache',
+];
+
 const String kDevtoolsStderr = '\n\nDevTools listening\n\n';
 
 void main() {
@@ -351,7 +358,7 @@ void main() {
     );
   });
 
-  testWithoutContext('can seed chrome temp directory with existing session data', () async {
+  testWithoutContext('can seed chrome temp directory with existing session data, excluding Cache folder', () async {
     final Completer<void> exitCompleter = Completer<void>.sync();
     final Directory dataDir = fileSystem.directory('chrome-stuff');
     final File preferencesFile = dataDir
@@ -362,9 +369,16 @@ void main() {
       ..writeAsStringSync('"exit_type":"Crashed"');
 
     final Directory defaultContentDirectory = dataDir
+      .childDirectory('Default')
+      .childDirectory('Foo');
+    defaultContentDirectory.createSync(recursive: true);
+    // Create Cache directories that should be skipped
+    for (final String cache in kCodeCache) {
+      dataDir
         .childDirectory('Default')
-        .childDirectory('Foo');
-        defaultContentDirectory.createSync(recursive: true);
+        .childDirectory(cache)
+        .createSync(recursive: true);
+    }
 
     processManager.addCommand(FakeCommand(
       command: const <String>[
@@ -397,7 +411,15 @@ void main() {
         .childDirectory('Default')
         .childDirectory('Foo');
 
-    expect(defaultContentDir.existsSync(), true);
+    expect(defaultContentDir, exists);
+
+    // Validate cache dirs are not copied.
+    for (final String cache in kCodeCache) {
+      expect(fileSystem
+        .directory('.tmp_rand0/flutter_tools_chrome_device.rand0')
+        .childDirectory('Default')
+        .childDirectory(cache), isNot(exists));
+    }
   });
 
   testWithoutContext('can retry launch when glibc bug happens', () async {