Support hot reload with a prebuilt loader (#6743)

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

@@ -785,7 +785,6 @@ class _AdbLogReader extends DeviceLogReader {
       DateTime time = _adbTimestampToDateTime(timestamp);
       if (time.isBefore(_timeOrigin)) {
         // Ignore log messages before the origin.
-        printTrace('skipped old log line: $line');
         return;
       }
     }
@@ -816,7 +815,6 @@ class _AdbLogReader extends DeviceLogReader {
         return;
       }
     }
-    printTrace('skipped log line: $line');
   }
 
   void _stop() {

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

@@ -62,6 +62,15 @@ class RunCommand extends RunCommandBase {
     argParser.addOption('use-application-binary',
         hide: !verboseHelp,
         help: 'Specify a pre-built application binary to use when running.');
+    argParser.addOption('snapshotter',
+        hide: !verboseHelp,
+        help: 'Specify the path to the sky_snapshot binary.');
+    argParser.addOption('packages',
+        hide: !verboseHelp,
+        help: 'Specify the path to the .packages file.');
+    argParser.addOption('project_root',
+        hide: !verboseHelp,
+        help: 'Specify the project root directory.');
     argParser.addFlag('machine',
         hide: !verboseHelp,
         help: 'Handle machine structured JSON command input\n'
@@ -138,7 +147,7 @@ class RunCommand extends RunCommandBase {
 
   bool shouldUseHotMode() {
     bool hotArg = argResults['hot'] ?? false;
-    final bool shouldUseHotMode = hotArg && !runningWithPrebuiltApplication;
+    final bool shouldUseHotMode = hotArg;
     return (getBuildMode() == BuildMode.debug) && shouldUseHotMode;
   }
 
@@ -220,7 +229,10 @@ class RunCommand extends RunCommandBase {
         device,
         target: targetFile,
         debuggingOptions: options,
-        benchmarkMode: argResults['benchmark']
+        benchmarkMode: argResults['benchmark'],
+        applicationBinary: argResults['use-application-binary'],
+        projectRootPath: argResults['project_root'],
+        packagesFilePath: argResults['packages'],
       );
     } else {
       runner = new RunAndStayResident(

packages/flutter_tools/lib/src/devfs.dart

@@ -252,20 +252,31 @@ class DevFS {
   /// Create a [DevFS] named [fsName] for the local files in [directory].
   DevFS(VMService serviceProtocol,
         String fsName,
-        this.rootDirectory)
+        this.rootDirectory, {
+        String packagesFilePath
+      })
     : _operations = new ServiceProtocolDevFSOperations(serviceProtocol),
       _httpWriter = new _DevFSHttpWriter(fsName, serviceProtocol),
-      fsName = fsName;
+      fsName = fsName {
+    _packagesFilePath =
+        packagesFilePath ?? path.join(rootDirectory.path, kPackagesFileName);
+  }
 
   DevFS.operations(this._operations,
                    this.fsName,
-                   this.rootDirectory)
+                   this.rootDirectory, {
-    : _httpWriter = null;
+                   String packagesFilePath,
+      })
+    : _httpWriter = null {
+    _packagesFilePath =
+        packagesFilePath ?? path.join(rootDirectory.path, kPackagesFileName);
+  }
 
   final DevFSOperations _operations;
   final _DevFSHttpWriter _httpWriter;
   final String fsName;
   final Directory rootDirectory;
+  String _packagesFilePath;
   final Map<String, DevFSEntry> _entries = <String, DevFSEntry>{};
   final Set<DevFSEntry> _dirtyEntries = new Set<DevFSEntry>();
   final Set<DevFSEntry> _deletedEntries = new Set<DevFSEntry>();
@@ -318,10 +329,10 @@ class DevFS {
                          fileFilter: fileFilter);
 
     printTrace('Scanning package files');
-    String packagesFilePath = path.join(rootDirectory.path, kPackagesFileName);
+
     StringBuffer sb;
-    if (FileSystemEntity.isFileSync(packagesFilePath)) {
+    if (FileSystemEntity.isFileSync(_packagesFilePath)) {
-      PackageMap packageMap = new PackageMap(kPackagesFileName);
+      PackageMap packageMap = new PackageMap(_packagesFilePath);
 
       for (String packageName in packageMap.map.keys) {
         Uri uri = packageMap.map[packageName];

packages/flutter_tools/lib/src/hot.dart

@@ -40,10 +40,12 @@ String getDevFSLoaderScript() {
 
 class DartDependencySetBuilder {
   DartDependencySetBuilder(this.mainScriptPath,
-                           this.projectRootPath);
+                           this.projectRootPath,
+                           this.packagesFilePath);
 
   final String mainScriptPath;
   final String projectRootPath;
+  final String packagesFilePath;
 
   Set<String> build() {
     final String skySnapshotPath =
@@ -51,7 +53,7 @@ class DartDependencySetBuilder {
 
     final List<String> args = <String>[
       skySnapshotPath,
-      '--packages=${path.absolute(PackageMap.globalPackagesPath)}',
+      '--packages=$packagesFilePath',
       '--print-deps',
       mainScriptPath
     ];
@@ -120,16 +122,24 @@ class HotRunner extends ResidentRunner {
     DebuggingOptions debuggingOptions,
     bool usesTerminalUI: true,
     this.benchmarkMode: false,
+    this.applicationBinary,
+    String projectRootPath,
+    String packagesFilePath,
   }) : super(device,
              target: target,
              debuggingOptions: debuggingOptions,
              usesTerminalUI: usesTerminalUI) {
-    _projectRootPath = Directory.current.path;
+    _projectRootPath = projectRootPath ?? Directory.current.path;
+    _packagesFilePath =
+            packagesFilePath ?? path.absolute(PackageMap.globalPackagesPath);
   }
 
   ApplicationPackage _package;
   String _mainPath;
   String _projectRootPath;
+  String _packagesFilePath;
+  final String applicationBinary;
+  bool get prebuiltMode => applicationBinary != null;
   Set<String> _dartDependencies;
   int _observatoryPort;
   final AssetBundle bundle = new AssetBundle();
@@ -144,6 +154,7 @@ class HotRunner extends ResidentRunner {
     bool shouldBuild: true
   }) {
     // Don't let uncaught errors kill the process.
+    assert(shouldBuild == !prebuiltMode);
     return Chain.capture(() {
       return _run(
         connectionInfoCompleter: connectionInfoCompleter,
@@ -162,7 +173,8 @@ class HotRunner extends ResidentRunner {
       return true;
     }
     DartDependencySetBuilder dartDependencySetBuilder =
-        new DartDependencySetBuilder(_mainPath, _projectRootPath);
+        new DartDependencySetBuilder(
+              _mainPath, _projectRootPath, _packagesFilePath);
     try {
       _dartDependencies = dartDependencySetBuilder.build();
     } catch (error) {
@@ -188,7 +200,7 @@ class HotRunner extends ResidentRunner {
       return 1;
     }
 
-    _package = getApplicationPackageForPlatform(device.platform);
+    _package = getApplicationPackageForPlatform(device.platform, applicationBinary: applicationBinary);
 
     if (_package == null) {
       String message = 'No application found for ${device.platform}.';
@@ -222,15 +234,10 @@ class HotRunner extends ResidentRunner {
     // TODO(devoncarew): Move this into the device.startApp() impls.
     if (_package != null) {
       printTrace("Stopping app '${_package.name}' on ${device.name}.");
-      // We don't wait for the stop command to complete.
+      await device.stopApp(_package);
-      device.stopApp(_package);
     }
 
-    // Allow any stop commands from above to start work.
+    if (prebuiltMode || device is AndroidDevice) {
-    await new Future<Duration>.delayed(Duration.ZERO);
-
-    // TODO(devoncarew): This fails for ios devices - we haven't built yet.
-    if (device is AndroidDevice) {
       printTrace('Running install command.');
       if (!(installApp(device, _package, uninstall: false)))
         return 1;
@@ -249,7 +256,8 @@ class HotRunner extends ResidentRunner {
       mainPath: getDevFSLoaderScript(),
       debuggingOptions: debuggingOptions,
       platformArgs: platformArgs,
-      route: route
+      route: route,
+      prebuiltApplication: prebuiltMode
     );
 
     LaunchResult result = await futureResult;
@@ -369,7 +377,8 @@ class HotRunner extends ResidentRunner {
     String fsName = path.basename(_projectRootPath);
     _devFS = new DevFS(vmService,
                        fsName,
-                       new Directory(_projectRootPath));
+                       new Directory(_projectRootPath),
+                       packagesFilePath: _packagesFilePath);
     return _devFS.create();
   }
 

packages/flutter_tools/test/src/context.dart

@@ -73,7 +73,10 @@ void testUsingContext(String description, dynamic testMethod(), {
         if (bufferLogger.errorText.isNotEmpty)
           print(bufferLogger.errorText);
       }
-      throw error;
+      // Previously the following line read "throw error;". This is bad because
+      // it drops the error's actual stacktrace. Use 'rethrow' to preserve
+      // the stacktrace.
+      rethrow;
     }
 
   }, timeout: timeout);