[flutter_tools] don't compute hashes of well known artifacts (#53848)

packages/flutter_tools/lib/src/aot.dart

@@ -81,6 +81,9 @@ class AotBuilder {
       buildDir: FlutterProject.current().dartTool.childDirectory('flutter_build'),
       cacheDir: null,
       flutterRootDir: globals.fs.directory(Cache.flutterRoot),
+      engineVersion: globals.artifacts.isLocalEngine
+        ? null
+        : globals.flutterVersion.engineRevision,
       defines: <String, String>{
         kTargetFile: mainDartFile ?? globals.fs.path.join('lib', 'main.dart'),
         kBuildMode: getNameForBuildMode(buildInfo.mode),

packages/flutter_tools/lib/src/artifacts.dart

@@ -169,6 +169,9 @@ abstract class Artifacts {
   // Returns which set of engine artifacts is currently used for the [platform]
   // and [mode] combination.
   String getEngineType(TargetPlatform platform, [ BuildMode mode ]);
+
+  /// Whether these artifacts correspond to a non-versioned local engine.
+  bool get isLocalEngine;
 }
 
 
@@ -405,6 +408,9 @@ class CachedArtifacts extends Artifacts {
     assert(false, 'Invalid platform $platform.');
     return null;
   }
+
+  @override
+  bool get isLocalEngine => false;
 }
 
 TargetPlatform _currentHostPlatform(Platform platform) {
@@ -576,6 +582,9 @@ class LocalEngineArtifacts extends Artifacts {
     }
     throw Exception('Unsupported platform $platform.');
   }
+
+  @override
+  bool get isLocalEngine => true;
 }
 
 /// An implementation of [Artifacts] that provides individual overrides.
@@ -618,4 +627,7 @@ class OverrideArtifacts implements Artifacts {
 
   @override
   String getEngineType(TargetPlatform platform, [ BuildMode mode ]) => parent.getEngineType(platform, mode);
+
+  @override
+  bool get isLocalEngine => parent.isLocalEngine;
 }

packages/flutter_tools/lib/src/build_system/build_system.dart

@@ -284,6 +284,8 @@ abstract class Target {
 ///    }
 class Environment {
   /// Create a new [Environment] object.
+  ///
+  /// [engineVersion] should be set to null for local engine builds.
   factory Environment({
     @required Directory projectDir,
     @required Directory outputDir,
@@ -293,6 +295,7 @@ class Environment {
     @required Logger logger,
     @required Artifacts artifacts,
     @required ProcessManager processManager,
+    @required String engineVersion,
     Directory buildDir,
     Map<String, String> defines = const <String, String>{},
     Map<String, String> inputs = const <String, String>{},
@@ -303,6 +306,10 @@ class Environment {
     String buildPrefix;
     final List<String> keys = defines.keys.toList()..sort();
     final StringBuffer buffer = StringBuffer();
+    // The engine revision is `null` for local or custom engines.
+    if (engineVersion != null) {
+      buffer.write(engineVersion);
+    }
     for (final String key in keys) {
       buffer.write(key);
       buffer.write(defines[key]);
@@ -326,6 +333,7 @@ class Environment {
       logger: logger,
       artifacts: artifacts,
       processManager: processManager,
+      engineVersion: engineVersion,
       inputs: inputs,
     );
   }
@@ -333,6 +341,7 @@ class Environment {
   /// Create a new [Environment] object for unit testing.
   ///
   /// Any directories not provided will fallback to a [testDirectory]
+  @visibleForTesting
   factory Environment.test(Directory testDirectory, {
     Directory projectDir,
     Directory outputDir,
@@ -341,6 +350,7 @@ class Environment {
     Directory buildDir,
     Map<String, String> defines = const <String, String>{},
     Map<String, String> inputs = const <String, String>{},
+    String engineVersion,
     @required FileSystem fileSystem,
     @required Logger logger,
     @required Artifacts artifacts,
@@ -358,6 +368,7 @@ class Environment {
       logger: logger,
       artifacts: artifacts,
       processManager: processManager,
+      engineVersion: engineVersion,
     );
   }
 
@@ -373,6 +384,7 @@ class Environment {
     @required this.logger,
     @required this.fileSystem,
     @required this.artifacts,
+    @required this.engineVersion,
     @required this.inputs,
   });
 
@@ -448,6 +460,9 @@ class Environment {
   final Artifacts artifacts;
 
   final FileSystem fileSystem;
+
+  /// The version of the current engine, or `null` if built with a local engine.
+  final String engineVersion;
 }
 
 /// The result information from the build system.

packages/flutter_tools/lib/src/build_system/source.dart

@@ -166,7 +166,19 @@ class SourceVisitor implements ResolvedFiles {
   /// Visit a [Source] which is defined by an [Artifact] from the flutter cache.
   ///
   /// If the [Artifact] points to a directory then all child files are included.
+  /// To increase the performance of builds that use a known revision of Flutter,
+  /// these are updated to point towards the engine.version file instead of
+  /// the artifact itself.
   void visitArtifact(Artifact artifact, TargetPlatform platform, BuildMode mode) {
+    // This is not a local engine.
+    if (environment.engineVersion != null) {
+      sources.add(environment.flutterRootDir
+        .childDirectory('bin')
+        .childDirectory('internal')
+        .childFile('engine.version'),
+      );
+      return;
+    }
     final String path = environment.artifacts
       .getArtifactPath(artifact, platform: platform, mode: mode);
     if (environment.fileSystem.isDirectorySync(path)) {
@@ -175,9 +187,9 @@ class SourceVisitor implements ResolvedFiles {
           if (entity is File)
             entity,
       ]);
-    } else {
-      sources.add(environment.fileSystem.file(path));
+      return;
     }
+    sources.add(environment.fileSystem.file(path));
   }
 }
 

packages/flutter_tools/lib/src/bundle.dart

@@ -122,6 +122,9 @@ Future<void> buildWithAssemble({
     buildDir: flutterProject.dartTool.childDirectory('flutter_build'),
     cacheDir: globals.cache.getRoot(),
     flutterRootDir: globals.fs.directory(Cache.flutterRoot),
+    engineVersion: globals.artifacts.isLocalEngine
+      ? null
+      : globals.flutterVersion.engineRevision,
     defines: <String, String>{
       kTargetFile: mainPath,
       kBuildMode: getNameForBuildMode(buildMode),

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

@@ -164,6 +164,9 @@ class AssembleCommand extends FlutterCommand {
       fileSystem: globals.fs,
       logger: globals.logger,
       processManager: globals.processManager,
+      engineVersion: globals.artifacts.isLocalEngine
+        ? null
+        : globals.flutterVersion.engineRevision
     );
     return result;
   }

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

@@ -462,6 +462,9 @@ end
         fileSystem: globals.fs,
         logger: globals.logger,
         processManager: globals.processManager,
+        engineVersion: globals.artifacts.isLocalEngine
+          ? null
+          : globals.flutterVersion.engineRevision,
       );
       final BuildResult result = await buildSystem.build(target, environment);
       if (!result.success) {

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

@@ -13,6 +13,7 @@ import '../build_system/build_system.dart';
 import '../build_system/targets/dart.dart';
 import '../build_system/targets/icon_tree_shaker.dart';
 import '../build_system/targets/web.dart';
+import '../cache.dart';
 import '../globals.dart' as globals;
 import '../platform_plugins.dart';
 import '../plugins.dart';
@@ -37,8 +38,8 @@ Future<void> buildWeb(
   final Status status = globals.logger.startProgress('Compiling $target for the Web...', timeout: null);
   final Stopwatch sw = Stopwatch()..start();
   try {
-    final BuildResult result = await globals.buildSystem.build(const WebServiceWorker(), Environment.test(
-      globals.fs.currentDirectory,
+    final BuildResult result = await globals.buildSystem.build(const WebServiceWorker(), Environment(
+      projectDir: globals.fs.currentDirectory,
       outputDir: globals.fs.directory(getWebBuildDirectory()),
       buildDir: flutterProject.directory
         .childDirectory('.dart_tool')
@@ -56,6 +57,11 @@ Future<void> buildWeb(
       fileSystem: globals.fs,
       logger: globals.logger,
       processManager: globals.processManager,
+      cacheDir: globals.cache.getRoot(),
+      engineVersion: globals.artifacts.isLocalEngine
+        ? null
+        : globals.flutterVersion.engineRevision,
+      flutterRootDir: globals.fs.directory(Cache.flutterRoot),
     ));
     if (!result.success) {
       for (final ExceptionMeasurement measurement in result.exceptions.values) {

packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:args/command_runner.dart';
+import 'package:flutter_tools/src/artifacts.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/build_system/build_system.dart';
 import 'package:flutter_tools/src/cache.dart';
@@ -96,6 +97,22 @@ void main() {
     expect(testLogger.errorText, isNot(contains(testStackTrace.toString())));
   });
 
+  testbed.test('flutter assemble does not inject engine revision with local-engine', () async {
+    Environment environment;
+    when(globals.artifacts.isLocalEngine).thenReturn(true);
+    when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
+      .thenAnswer((Invocation invocation) async {
+        environment = invocation.positionalArguments[1] as Environment;
+        return BuildResult(success: true);
+      });
+    final CommandRunner<void> commandRunner = createTestCommandRunner(AssembleCommand());
+    await commandRunner.run(<String>['assemble', '-o Output', 'debug_macos_bundle_flutter_assets']);
+
+    expect(environment.engineVersion, isNull);
+  }, overrides: <Type, Generator>{
+    Artifacts: () => MockLocalEngineArtifacts()
+  });
+
   testbed.test('flutter assemble only writes input and output files when the values change', () async {
     when(globals.buildSystem.build(any, any, buildSystemConfig: anyNamed('buildSystemConfig')))
       .thenAnswer((Invocation invocation) async {
@@ -156,3 +173,4 @@ void main() {
 }
 
 class MockBuildSystem extends Mock implements BuildSystem {}
+class MockLocalEngineArtifacts extends Mock implements LocalEngineArtifacts {}

packages/flutter_tools/test/general.shard/build_system/build_system_test.dart

@@ -84,9 +84,11 @@ void main() {
       ..inputs = const <Source>[
         Source.pattern('{PROJECT_DIR}/foo.dart'),
       ];
+    final MockArtifacts artifacts = MockArtifacts();
+    when(artifacts.isLocalEngine).thenReturn(false);
     environment = Environment.test(
       fileSystem.currentDirectory,
-      artifacts: MockArtifacts(),
+      artifacts: artifacts,
       processManager: FakeProcessManager.any(),
       fileSystem: fileSystem,
       logger: BufferLogger.test(),

packages/flutter_tools/test/general.shard/build_system/source_test.dart

@@ -17,15 +17,16 @@ import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/testbed.dart';
 
+final Platform windowsPlatform = FakePlatform(
+  operatingSystem: 'windows',
+);
+
 void main() {
   Testbed testbed;
   SourceVisitor visitor;
   Environment environment;
-  MockPlatform mockPlatform;
 
   setUp(() {
-    mockPlatform = MockPlatform();
-    when(mockPlatform.isWindows).thenReturn(true);
     testbed = Testbed(setup: () {
       globals.fs.directory('cache').createSync();
       final Directory outputs = globals.fs.directory('outputs')
@@ -37,6 +38,7 @@ void main() {
         processManager: FakeProcessManager.any(),
         fileSystem: globals.fs,
         logger: globals.logger,
+        engineVersion: null, // simulate a local engine.
       );
       visitor = SourceVisitor(environment);
       environment.buildDir.createSync(recursive: true);
@@ -203,7 +205,7 @@ void main() {
     expect(visitor.sources.single.path, r'C:\foo\bar.txt');
     expect(visitor.containsNewDepfile, false);
   }, overrides: <Type, Generator>{
-    Platform: () => mockPlatform,
+    Platform: () => windowsPlatform,
   }));
 
   test('can parse depfile with spaces in paths', () => testbed.run(() {
@@ -214,7 +216,26 @@ void main() {
     expect(visitor.sources.single.path, r'foo bar.txt');
     expect(visitor.containsNewDepfile, false);
   }));
+
+  test('Non-local engine builds use the engine.version file as an Artifact dependency', () => testbed.run(() {
+    final MockArtifacts artifacts = MockArtifacts();
+    final Environment environment = Environment.test(
+      globals.fs.currentDirectory,
+      artifacts: artifacts, // using real artifacts
+      processManager: FakeProcessManager.any(),
+      fileSystem: globals.fs,
+      logger: globals.logger,
+      engineVersion: 'abcdefghijklmon' // Use a versioned engine.
+    );
+    visitor = SourceVisitor(environment);
+
+    const Source fizzSource = Source.artifact(Artifact.windowsDesktopPath, platform: TargetPlatform.windows_x64);
+    fizzSource.accept(visitor);
+
+    expect(visitor.sources.single.path, contains('engine.version'));
+    verifyNever(artifacts.getArtifactPath(
+      any, platform: anyNamed('platform'), mode: anyNamed('mode')));
+  }));
 }
 
-class MockPlatform extends Mock implements Platform {}
 class MockArtifacts extends Mock implements Artifacts {}

packages/flutter_tools/test/general.shard/tester/flutter_tester_test.dart

@@ -144,6 +144,8 @@ void main() {
           any,
           mode: anyNamed('mode')
         )).thenReturn(artifactPath);
+        when(mockArtifacts.isLocalEngine)
+          .thenReturn(false);
 
         when(mockBuildSystem.build(
           any,