Initialize from dill on tests (#20414)

packages/flutter_tools/lib/src/compile.dart

@@ -248,14 +248,16 @@ class _CompileExpressionRequest extends _CompilationRequest {
 class ResidentCompiler {
   ResidentCompiler(this._sdkRoot, {bool trackWidgetCreation = false,
       String packagesPath, List<String> fileSystemRoots, String fileSystemScheme ,
-      CompilerMessageConsumer compilerMessageConsumer = printError})
+      CompilerMessageConsumer compilerMessageConsumer = printError,
+      String initializeFromDill})
     : assert(_sdkRoot != null),
       _trackWidgetCreation = trackWidgetCreation,
       _packagesPath = packagesPath,
       _fileSystemRoots = fileSystemRoots,
       _fileSystemScheme = fileSystemScheme,
       _stdoutHandler = new _StdoutHandler(consumer: compilerMessageConsumer),
-      _controller = new StreamController<_CompilationRequest>() {
+      _controller = new StreamController<_CompilationRequest>(),
+      _initializeFromDill = initializeFromDill {
     // This is a URI, not a file path, so the forward slash is correct even on Windows.
     if (!_sdkRoot.endsWith('/'))
       _sdkRoot = '$_sdkRoot/';
@@ -268,6 +270,7 @@ class ResidentCompiler {
   String _sdkRoot;
   Process _server;
   final _StdoutHandler _stdoutHandler;
+  String _initializeFromDill;
 
   final StreamController<_CompilationRequest> _controller;
 
@@ -362,6 +365,9 @@ class ResidentCompiler {
     if (_fileSystemScheme != null) {
       command.addAll(<String>['--filesystem-scheme', _fileSystemScheme]);
     }
+    if (_initializeFromDill != null) {
+      command.addAll(<String>['--initialize-from-dill', _initializeFromDill]);
+    }
     printTrace(command.join(' '));
     _server = await processManager.start(command);
     _server.stdout

packages/flutter_tools/lib/src/test/flutter_platform.dart

@@ -18,6 +18,7 @@ import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../base/process_manager.dart';
+import '../build_info.dart';
 import '../compile.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
@@ -74,6 +75,7 @@ void installHook({
   bool updateGoldens = false,
   int observatoryPort,
   InternetAddressType serverType = InternetAddressType.IPv4,
+  Uri projectRootDirectory,
 }) {
   assert(!enableObservatory || (!startPaused && observatoryPort == null));
   hack.registerPlatformPlugin(
@@ -91,6 +93,7 @@ void installHook({
       precompiledDillPath: precompiledDillPath,
       trackWidgetCreation: trackWidgetCreation,
       updateGoldens: updateGoldens,
+      projectRootDirectory: projectRootDirectory,
     ),
   );
 }
@@ -198,7 +201,7 @@ class _CompilationRequest {
 // This class is a wrapper around compiler that allows multiple isolates to
 // enqueue compilation requests, but ensures only one compilation at a time.
 class _Compiler {
-  _Compiler(bool trackWidgetCreation) {
+  _Compiler(bool trackWidgetCreation, Uri projectRootDirectory) {
     // Compiler maintains and updates single incremental dill file.
     // Incremental compilation requests done for each test copy that file away
     // for independent execution.
@@ -223,12 +226,15 @@ class _Compiler {
       printError('$message');
     }
 
+    final String testFilePath = fs.path.join(fs.path.fromUri(projectRootDirectory), getBuildDirectory(), 'testfile.dill');
+
     ResidentCompiler createCompiler() {
       return new ResidentCompiler(
         artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
         packagesPath: PackageMap.globalPackagesPath,
         trackWidgetCreation: trackWidgetCreation,
         compilerMessageConsumer: reportCompilerMessage,
+        initializeFromDill: testFilePath
       );
     }
 
@@ -244,7 +250,11 @@ class _Compiler {
           final _CompilationRequest request = compilationQueue.first;
           printTrace('Compiling ${request.path}');
           final Stopwatch compilerTime = new Stopwatch()..start();
-          compiler ??= createCompiler();
+          bool firstCompile = false;
+          if (compiler == null) {
+            compiler = createCompiler();
+            firstCompile = true;
+          }
           suppressOutput = false;
           final CompilerOutput compilerOutput = await handleTimeout<CompilerOutput>(
               compiler.recompile(
@@ -262,8 +272,16 @@ class _Compiler {
             request.result.complete(null);
             await _shutdown();
           } else {
-            final File kernelReadyToRun =
-                await fs.file(outputPath).copy('${request.path}.dill');
+            final File outputFile = fs.file(outputPath);
+            final File kernelReadyToRun = await outputFile.copy('${request.path}.dill');
+            final File testCache = fs.file(testFilePath);
+            if (firstCompile || !testCache.existsSync() || (testCache.lengthSync() < outputFile.lengthSync())) {
+              // The idea is to keep the cache file up-to-date and include as
+              // much as possible in an effort to re-use as many packages as
+              // possible.
+              ensureDirectoryExists(testFilePath);
+              await outputFile.copy(testFilePath);
+            }
             request.result.complete(kernelReadyToRun.path);
             compiler.accept();
             compiler.reset();
@@ -326,6 +344,7 @@ class _FlutterPlatform extends PlatformPlugin {
     this.precompiledDillPath,
     this.trackWidgetCreation,
     this.updateGoldens,
+    this.projectRootDirectory,
   }) : assert(shellPath != null);
 
   final String shellPath;
@@ -340,6 +359,7 @@ class _FlutterPlatform extends PlatformPlugin {
   final String precompiledDillPath;
   final bool trackWidgetCreation;
   final bool updateGoldens;
+  final Uri projectRootDirectory;
 
   Directory fontsDirectory;
   _Compiler compiler;
@@ -437,7 +457,7 @@ class _FlutterPlatform extends PlatformPlugin {
 
       if (previewDart2 && precompiledDillPath == null) {
         // Lazily instantiate compiler so it is built only if it is actually used.
-        compiler ??= new _Compiler(trackWidgetCreation);
+        compiler ??= new _Compiler(trackWidgetCreation, projectRootDirectory);
         mainDart = await compiler.compile(mainDart);
 
         if (mainDart == null) {

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

@@ -87,6 +87,7 @@ Future<int> runTests(
     precompiledDillPath: precompiledDillPath,
     trackWidgetCreation: trackWidgetCreation,
     updateGoldens: updateGoldens,
+    projectRootDirectory: fs.currentDirectory.uri,
   );
 
   // Make the global packages path absolute.