[flutter_tools] add --analyze-size flag (#62697)

packages/flutter_tools/lib/src/android/gradle.dart

@@ -9,6 +9,7 @@ import 'package:meta/meta.dart';
 import 'package:xml/xml.dart';
 
 import '../artifacts.dart';
+import '../base/analyze_size.dart';
 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
@@ -18,6 +19,7 @@ import '../base/terminal.dart';
 import '../base/utils.dart';
 import '../build_info.dart';
 import '../cache.dart';
+import '../convert.dart';
 import '../flutter_manifest.dart';
 import '../globals.dart' as globals;
 import '../project.dart';
@@ -499,6 +501,25 @@ Future<void> buildGradleApp({
     '$successMark Built ${globals.fs.path.relative(apkFile.path)}$appSize.',
     color: TerminalColor.green,
   );
+
+  // Call size analyzer if --analyze-size flag was provided.
+  if (buildInfo.analyzeSize != null && !globals.platform.isWindows) {
+    final SizeAnalyzer sizeAnalyzer = SizeAnalyzer(
+      fileSystem: globals.fs,
+      logger: globals.logger,
+      processUtils: ProcessUtils.instance,
+    );
+    final Map<String, Object> output = await sizeAnalyzer.analyzeApkSizeAndAotSnapshot(
+      apk: apkFile,
+      aotSnapshot: globals.fs.file(buildInfo.analyzeSize),
+    );
+    final File outputFile = globals.fsUtils.getUniqueFile(globals.fs.currentDirectory, 'apk-analysis', 'json')
+      ..writeAsStringSync(jsonEncode(output));
+    // This message is used as a sentinel in analyze_apk_size_test.dart
+    globals.printStatus(
+      'A summary of your APK analysis can be found at: ${outputFile.path}',
+    );
+  }
 }
 
 /// Builds AAR and POM files.

packages/flutter_tools/lib/src/build_info.dart

@@ -33,6 +33,7 @@ class BuildInfo {
     this.performanceMeasurementFile,
     this.packagesPath = '.packages',
     this.nullSafetyMode = NullSafetyMode.autodetect,
+    this.analyzeSize,
   });
 
   final BuildMode mode;
@@ -113,6 +114,10 @@ class BuildInfo {
   /// rerun tasks.
   final String performanceMeasurementFile;
 
+  /// If provided, an output file where a v8-style heapsnapshot will be written for size
+  /// profiling.
+  final String analyzeSize;
+
   static const BuildInfo debug = BuildInfo(BuildMode.debug, null, treeShakeIcons: false);
   static const BuildInfo profile = BuildInfo(BuildMode.profile, null, treeShakeIcons: kIconTreeShakerEnabledDefault);
   static const BuildInfo jitRelease = BuildInfo(BuildMode.jitRelease, null, treeShakeIcons: kIconTreeShakerEnabledDefault);

packages/flutter_tools/lib/src/commands/build_apk.dart

@@ -34,6 +34,7 @@ class BuildApkCommand extends BuildSubCommand {
     addEnableExperimentation(hide: !verboseHelp);
     addBuildPerformanceFile(hide: !verboseHelp);
     addNullSafetyModeOptions(hide: !verboseHelp);
+    usesAnalyzeSizeFlag();
     argParser
       ..addFlag('split-per-abi',
         negatable: false,

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -112,6 +112,7 @@ class FlutterOptions {
   static const String kPerformanceMeasurementFile = 'performance-measurement-file';
   static const String kNullSafety = 'sound-null-safety';
   static const String kDeviceUser = 'device-user';
+  static const String kAnalyzeSize = 'analyze-size';
 }
 
 abstract class FlutterCommand extends Command<void> {
@@ -605,6 +606,15 @@ abstract class FlutterCommand extends Command<void> {
     );
   }
 
+  void usesAnalyzeSizeFlag() {
+    argParser.addFlag(
+      FlutterOptions.kAnalyzeSize,
+      defaultsTo: false,
+      help: 'Whether to produce additonal profile information for artifact output size. '
+        'This flag is only support on release builds on macOS/Linux hosts.'
+    );
+  }
+
   /// Compute the [BuildInfo] for the current flutter command.
   /// Commands that build multiple build modes can pass in a [forcedBuildMode]
   /// to be used instead of parsing flags.
@@ -640,6 +650,15 @@ abstract class FlutterCommand extends Command<void> {
       }
     }
 
+    String analyzeSize;
+    if (argParser.options.containsKey(FlutterOptions.kAnalyzeSize)
+      && boolArg(FlutterOptions.kAnalyzeSize)
+      && !globals.platform.isWindows) {
+      final File file = globals.fsUtils.getUniqueFile(globals.fs.currentDirectory, 'flutter_size', 'json');
+      extraGenSnapshotOptions.add('--write-v8-snapshot-profile-to=${file.path}');
+      analyzeSize = file.path;
+    }
+
     NullSafetyMode nullSafetyMode = NullSafetyMode.unsound;
     if (argParser.options.containsKey(FlutterOptions.kNullSafety)) {
       final bool nullSafety = boolArg(FlutterOptions.kNullSafety);
@@ -671,6 +690,10 @@ abstract class FlutterCommand extends Command<void> {
       );
     }
     final BuildMode buildMode = forcedBuildMode ?? getBuildMode();
+    if (buildMode != BuildMode.release && analyzeSize != null) {
+      throwToolExit('--analyze-size can only be used on release builds.');
+    }
+
     final bool treeShakeIcons = argParser.options.containsKey('tree-shake-icons')
       && buildMode.isPrecompiled
       && boolArg('tree-shake-icons');
@@ -715,6 +738,7 @@ abstract class FlutterCommand extends Command<void> {
       performanceMeasurementFile: performanceMeasurementFile,
       packagesPath: globalResults['packages'] as String ?? '.packages',
       nullSafetyMode: nullSafetyMode,
+      analyzeSize: analyzeSize,
     );
   }
 

packages/flutter_tools/test/integration.shard/analyze_size_apk_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/base/platform.dart';
+import 'package:process/process.dart';
+import 'package:flutter_tools/src/globals.dart' as globals;
+
+import '../src/common.dart';
+
+const String debugMessage = 'A summary of your APK analysis can be found at: ';
+
+void main() {
+  test('--analyze-size flag produces expected output on hello_world', () async {
+    final String flutterBin = globals.fs.path.join(getFlutterRoot(), 'bin', 'flutter');
+    final ProcessResult result = await const LocalProcessManager().run(<String>[
+      flutterBin,
+      'build',
+      'apk',
+      '--analyze-size',
+    ], workingDirectory: globals.fs.path.join(getFlutterRoot(), 'examples', 'hello_world'));
+
+    print(result.stdout);
+    print(result.stderr);
+    expect(result.stdout.toString(), contains('app-release.apk (total compressed)'));
+
+    final String line = result.stdout.toString()
+      .split('\n')
+      .firstWhere((String line) => line.contains(debugMessage));
+
+    expect(globals.fs.file(globals.fs.path.join(line.split(debugMessage).last.trim())).existsSync(), true);
+    expect(result.exitCode, 0);
+  }, skip: const LocalPlatform().isWindows); // Not yet supported on Windows
+}