Provide user feedback on slow Gradle operations (#11015)

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

@@ -360,7 +360,7 @@ class AndroidDevice extends Device {
       );
       // Package has been built, so we can get the updated application ID and
       // activity name from the .apk.
-      package = new AndroidApk.fromCurrentDirectory();
+      package = await AndroidApk.fromCurrentDirectory();
     }
 
     printTrace("Stopping app '${package.name}' on $name.");

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

@@ -25,6 +25,7 @@ const String gradleAppOutDirV1 = 'android/app/build/outputs/apk';
 const String gradleVersion = '3.3';
 
 String _cachedGradleAppOutDirV2;
+String _cachedGradleExecutable;
 
 enum FlutterPluginVersion {
   none,
@@ -57,7 +58,7 @@ FlutterPluginVersion get flutterPluginVersion {
   return FlutterPluginVersion.none;
 }
 
-String getGradleAppOut() {
+Future<String> getGradleAppOut() async {
   switch (flutterPluginVersion) {
     case FlutterPluginVersion.none:
       // Fall through. Pretend we're v1, and just go with it.
@@ -66,27 +67,29 @@ String getGradleAppOut() {
     case FlutterPluginVersion.managed:
       // Fall through. The managed plugin matches plugin v2 for now.
     case FlutterPluginVersion.v2:
-      return '${getGradleAppOutDirV2()}/app.apk';
+      return '${await _getGradleAppOutDirV2()}/app.apk';
   }
   return null;
 }
 
-String getGradleAppOutDirV2() {
+Future<String> _getGradleAppOutDirV2() async {
-  _cachedGradleAppOutDirV2 ??= _calculateGradleAppOutDirV2();
+  _cachedGradleAppOutDirV2 ??= await _calculateGradleAppOutDirV2();
   return _cachedGradleAppOutDirV2;
 }
 
-// Note: this call takes about a second to complete.
+// Note: Dependencies are resolved and possibly downloaded as a side-effect
-String _calculateGradleAppOutDirV2() {
+// of calculating the app properties using Gradle. This may take minutes.
-  final String gradle = ensureGradle();
+Future<String> _calculateGradleAppOutDirV2() async {
+  final String gradle = await _ensureGradle();
   updateLocalProperties();
   try {
-    final String properties = runCheckedSync(
+    final Status status = logger.startProgress('Resolving dependencies...', expectSlowOperation: true);
+    final RunResult runResult = await runCheckedAsync(
       <String>[gradle, 'app:properties'],
       workingDirectory: 'android',
-      hideStdout: true,
       environment: _gradleEnv,
     );
+    final String properties = runResult.stdout.trim();
     String buildDir = properties
         .split('\n')
         .firstWhere((String s) => s.startsWith('buildDir: '))
@@ -97,6 +100,7 @@ String _calculateGradleAppOutDirV2() {
       // Relativize path, snip current directory + separating '/'.
       buildDir = buildDir.substring(currentDirectory.length + 1);
     }
+    status.stop();
     return '$buildDir/outputs/apk';
   } catch (e) {
     printError('Error running gradle: $e');
@@ -105,7 +109,7 @@ String _calculateGradleAppOutDirV2() {
   return gradleAppOutDirV1;
 }
 
-String locateProjectGradlew({ bool ensureExecutable: true }) {
+String _locateProjectGradlew({ bool ensureExecutable: true }) {
   final String path = fs.path.join(
       'android', platform.isWindows ? 'gradlew.bat' : 'gradlew'
   );
@@ -120,12 +124,27 @@ String locateProjectGradlew({ bool ensureExecutable: true }) {
   }
 }
 
-String ensureGradle() {
+Future<String> _ensureGradle() async {
-  String gradle = locateProjectGradlew();
+  _cachedGradleExecutable ??= await _initializeGradle();
+  return _cachedGradleExecutable;
+}
+
+// Note: Gradle may be bootstrapped and possibly downloaded as a side-effect
+// of validating the Gradle executable. This may take several seconds.
+Future<String> _initializeGradle() async {
+  final Status status = logger.startProgress('Initializing Gradle...', expectSlowOperation: true);
+  String gradle = _locateProjectGradlew();
   if (gradle == null) {
     _injectGradleWrapper();
-    gradle = locateProjectGradlew();
+    gradle = _locateProjectGradlew();
   }
+  if (gradle == null)
+    throwToolExit('Unable to locate gradlew script');
+  printTrace('Using gradle from $gradle.');
+  // Validates the Gradle executable by asking for its version.
+  // Makes Gradle Wrapper download and install Gradle distribution, if needed.
+  await runCheckedAsync(<String>[gradle, '-v'], environment: _gradleEnv);
+  status.stop();
   return gradle;
 }
 
@@ -183,24 +202,24 @@ Future<Null> buildGradleProject(BuildMode buildMode, String target, String kerne
 
   injectPlugins();
 
-  final String gradle = ensureGradle();
+  final String gradle = await _ensureGradle();
 
   switch (flutterPluginVersion) {
     case FlutterPluginVersion.none:
       // Fall through. Pretend it's v1, and just go for it.
     case FlutterPluginVersion.v1:
-      return buildGradleProjectV1(gradle);
+      return _buildGradleProjectV1(gradle);
     case FlutterPluginVersion.managed:
       // Fall through. Managed plugin builds the same way as plugin v2.
     case FlutterPluginVersion.v2:
-      return buildGradleProjectV2(gradle, buildModeName, target, kernelPath);
+      return _buildGradleProjectV2(gradle, buildModeName, target, kernelPath);
   }
 }
 
-Future<Null> buildGradleProjectV1(String gradle) async {
+Future<Null> _buildGradleProjectV1(String gradle) async {
-  // Run 'gradle build'.
+  // Run 'gradlew build'.
-  final Status status = logger.startProgress('Running \'gradle build\'...', expectSlowOperation: true);
+  final Status status = logger.startProgress('Running \'gradlew build\'...', expectSlowOperation: true);
-  final int exitcode = await runCommandAndStreamOutput(
+  final int exitCode = await runCommandAndStreamOutput(
     <String>[fs.file(gradle).absolute.path, 'build'],
     workingDirectory: 'android',
     allowReentrantFlutter: true,
@@ -208,8 +227,8 @@ Future<Null> buildGradleProjectV1(String gradle) async {
   );
   status.stop();
 
-  if (exitcode != 0)
+  if (exitCode != 0)
-    throwToolExit('Gradle build failed: $exitcode', exitCode: exitcode);
+    throwToolExit('Gradle build failed: $exitCode', exitCode: exitCode);
 
   final File apkFile = fs.file(gradleAppOutV1);
   printStatus('Built $gradleAppOutV1 (${getSizeAsMB(apkFile.lengthSync())}).');
@@ -226,10 +245,10 @@ File findApkFile(String buildDirectory, String buildModeName) {
   return null;
 }
 
-Future<Null> buildGradleProjectV2(String gradle, String buildModeName, String target, String kernelPath) async {
+Future<Null> _buildGradleProjectV2(String gradle, String buildModeName, String target, String kernelPath) async {
   final String assembleTask = "assemble${toTitleCase(buildModeName)}";
 
-  // Run 'gradle assemble<BuildMode>'.
+  // Run 'gradlew assemble<BuildMode>'.
   final Status status = logger.startProgress('Running \'gradlew $assembleTask\'...', expectSlowOperation: true);
   final String gradlePath = fs.file(gradle).absolute.path;
   final List<String> command = <String>[gradlePath];
@@ -258,7 +277,7 @@ Future<Null> buildGradleProjectV2(String gradle, String buildModeName, String ta
   if (exitcode != 0)
     throwToolExit('Gradle build failed: $exitcode', exitCode: exitcode);
 
-  final String buildDirectory = getGradleAppOutDirV2();
+  final String buildDirectory = await _getGradleAppOutDirV2();
   final File apkFile = findApkFile(buildDirectory, buildModeName);
   if (apkFile == null)
     throwToolExit('Gradle build failed to produce an Android package.');

packages/flutter_tools/lib/src/application_package.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:meta/meta.dart' show required;
 import 'package:xml/xml.dart' as xml;
 
@@ -78,21 +80,21 @@ class AndroidApk extends ApplicationPackage {
   }
 
   /// Creates a new AndroidApk based on the information in the Android manifest.
-  factory AndroidApk.fromCurrentDirectory() {
+  static Future<AndroidApk> fromCurrentDirectory() async {
     String manifestPath;
     String apkPath;
 
     if (isProjectUsingGradle()) {
-      if (fs.file(getGradleAppOut()).existsSync()) {
+      final String apkPath = await getGradleAppOut();
+      if (fs.file(apkPath).existsSync()) {
         // Grab information from the .apk. The gradle build script might alter
         // the application Id, so we need to look at what was actually built.
-        return new AndroidApk.fromApk(getGradleAppOut());
+        return new AndroidApk.fromApk(apkPath);
       }
       // The .apk hasn't been built yet, so we work with what we have. The run
       // command will grab a new AndroidApk after building, to get the updated
       // IDs.
       manifestPath = gradleManifestPath;
-      apkPath = getGradleAppOut();
     } else {
       manifestPath = fs.path.join('android', 'AndroidManifest.xml');
       apkPath = fs.path.join(getAndroidBuildDirectory(), 'app.apk');
@@ -251,15 +253,15 @@ class PrebuiltIOSApp extends IOSApp {
   String get _bundlePath => bundleDir.path;
 }
 
-ApplicationPackage getApplicationPackageForPlatform(TargetPlatform platform, {
+Future<ApplicationPackage> getApplicationPackageForPlatform(TargetPlatform platform, {
   String applicationBinary
-}) {
+}) async {
   switch (platform) {
     case TargetPlatform.android_arm:
     case TargetPlatform.android_x64:
     case TargetPlatform.android_x86:
       return applicationBinary == null
-          ? new AndroidApk.fromCurrentDirectory()
+          ? await AndroidApk.fromCurrentDirectory()
           : new AndroidApk.fromApk(applicationBinary);
     case TargetPlatform.ios:
       return applicationBinary == null
@@ -281,12 +283,12 @@ class ApplicationPackageStore {
 
   ApplicationPackageStore({ this.android, this.iOS });
 
-  ApplicationPackage getPackageForPlatform(TargetPlatform platform) {
+  Future<ApplicationPackage> getPackageForPlatform(TargetPlatform platform) async {
     switch (platform) {
       case TargetPlatform.android_arm:
       case TargetPlatform.android_x64:
       case TargetPlatform.android_x86:
-        android ??= new AndroidApk.fromCurrentDirectory();
+        android ??= await AndroidApk.fromCurrentDirectory();
         return android;
       case TargetPlatform.ios:
         iOS ??= new IOSApp.fromCurrentDirectory();

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

@@ -45,7 +45,7 @@ class BuildIOSCommand extends BuildSubCommand {
     if (getCurrentHostPlatform() != HostPlatform.darwin_x64)
       throwToolExit('Building for iOS is only supported on the Mac.');
 
-    final BuildableIOSApp app = applicationPackages.getPackageForPlatform(TargetPlatform.ios);
+    final BuildableIOSApp app = await applicationPackages.getPackageForPlatform(TargetPlatform.ios);
 
     if (app == null)
       throwToolExit('Application not configured for iOS');

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

@@ -229,7 +229,7 @@ Future<LaunchResult> _startApp(DriveCommand command) async {
   await appStopper(command);
 
   printTrace('Installing application package.');
-  final ApplicationPackage package = command.applicationPackages
+  final ApplicationPackage package = await command.applicationPackages
       .getPackageForPlatform(await command.device.targetPlatform);
   if (await command.device.isAppInstalled(package))
     await command.device.uninstallApp(package);
@@ -304,7 +304,7 @@ void restoreAppStopper() {
 
 Future<bool> _stopApp(DriveCommand command) async {
   printTrace('Stopping application.');
-  final ApplicationPackage package = command.applicationPackages.getPackageForPlatform(await command.device.targetPlatform);
+  final ApplicationPackage package = await command.applicationPackages.getPackageForPlatform(await command.device.targetPlatform);
   final bool stopped = await command.device.stopApp(package);
   await command._deviceLogSubscription?.cancel();
   return stopped;

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

@@ -31,7 +31,7 @@ class InstallCommand extends FlutterCommand {
 
   @override
   Future<Null> runCommand() async {
-    final ApplicationPackage package = applicationPackages.getPackageForPlatform(await device.targetPlatform);
+    final ApplicationPackage package = await applicationPackages.getPackageForPlatform(await device.targetPlatform);
 
     Cache.releaseLockEarly();
 

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

@@ -32,7 +32,7 @@ class StopCommand extends FlutterCommand {
   @override
   Future<Null> runCommand() async {
     final TargetPlatform targetPlatform = await device.targetPlatform;
-    final ApplicationPackage app = applicationPackages.getPackageForPlatform(targetPlatform);
+    final ApplicationPackage app = await applicationPackages.getPackageForPlatform(targetPlatform);
     if (app == null) {
       final String platformName = getNameForTargetPlatform(targetPlatform);
       throwToolExit('No Flutter application for $platformName found in the current directory.');

packages/flutter_tools/lib/src/plugins.dart

@@ -179,7 +179,7 @@ void _writeIOSPluginRegistry(String directory, List<Plugin> plugins) {
 }
 
 /// Finds Flutter plugins in the pubspec.yaml, creates platform injection
-/// registries classes and add them to the build depedencies.
+/// registries classes and add them to the build dependencies.
 ///
 /// Returns whether any Flutter plugins are added.
 bool injectPlugins({String directory}) {

packages/flutter_tools/lib/src/resident_runner.dart

@@ -210,7 +210,7 @@ class FlutterDevice {
     printStatus('Launching ${getDisplayPath(hotRunner.mainPath)} on ${device.name} in $modeName mode...');
 
     final TargetPlatform targetPlatform = await device.targetPlatform;
-    package = getApplicationPackageForPlatform(
+    package = await getApplicationPackageForPlatform(
       targetPlatform,
       applicationBinary: hotRunner.applicationBinary
     );
@@ -261,7 +261,7 @@ class FlutterDevice {
     bool shouldBuild: true,
   }) async {
     final TargetPlatform targetPlatform = await device.targetPlatform;
-    package = getApplicationPackageForPlatform(
+    package = await getApplicationPackageForPlatform(
       targetPlatform,
       applicationBinary: coldRunner.applicationBinary
     );