Configure ArtifactStore for all commands and make 'package-root' universal

This makes the 'package-root' option universal for sky_tools and configures the
ArtifactStore with it statically at startup. The actual sky_engine revision
is computed on demand.

packages/flutter_tools/bin/sky_tools.dart

@@ -8,6 +8,7 @@ import 'package:args/args.dart';
 import 'package:args/command_runner.dart';
 import 'package:logging/logging.dart';
 import 'package:sky_tools/src/application_package.dart';
+import 'package:sky_tools/src/artifacts.dart';
 import 'package:sky_tools/src/build.dart';
 import 'package:sky_tools/src/cache.dart';
 import 'package:sky_tools/src/init.dart';
@@ -72,6 +73,9 @@ class FlutterCommandRunner extends CommandRunner {
             'Path to your iOS Simulator Release out directory, if you are building Sky locally. '
             'This path is relative to sky-src-path. Not normally required.',
         defaultsTo: 'out/ios_sim_Release/');
+    argParser.addOption('package-root',
+        help: 'Path to your packages directory.',
+        defaultsTo: 'packages');
   }
 
   Future<int> runCommand(ArgResults topLevelResults) async {
@@ -89,6 +93,7 @@ class FlutterCommandRunner extends CommandRunner {
   }
 
   void _setupPaths(ArgResults results) {
+    ArtifactStore.packageRoot = results['package-root'];
     if (results['debug'] || results['release']) {
       if (results['sky-src-path'] == null) {
         // TODO(iansf): Figure out how to get the default src path

packages/flutter_tools/lib/src/artifacts.dart

@@ -15,21 +15,21 @@ final Logger _logging = new Logger('sky_tools.artifacts');
 enum Artifact { FlutterCompiler, SkyViewerMojo, }
 
 class ArtifactStore {
-  String _engineRevision;
-  final String packageRoot;
+  static String packageRoot;
+  static String _engineRevision;
 
-  ArtifactStore(this.packageRoot) {
+  static String get engineRevision {
+    if (_engineRevision == null)
       _engineRevision = new File(path.join(packageRoot, 'sky_engine', 'REVISION')).readAsStringSync();
+    return _engineRevision;
   }
 
-  String get engineRevision => _engineRevision;
-
   // Keep in sync with https://github.com/flutter/engine/blob/master/sky/tools/big_red_button.py#L50
-  String googleStorageUrl(String category, String platform) {
+  static String googleStorageUrl(String category, String platform) {
     return 'https://storage.googleapis.com/mojo/sky/${category}/${platform}/${engineRevision}/';
   }
 
-  Future _downloadFile(String url, File file) async {
+  static Future _downloadFile(String url, File file) async {
     _logging.fine('Downloading $url to ${file.path}');
     HttpClient httpClient = new HttpClient();
     HttpClientRequest request = await httpClient.getUrl(Uri.parse(url));
@@ -42,7 +42,7 @@ class ArtifactStore {
     _logging.fine('Wrote file');
   }
 
-  Future<Directory> _cacheDir() async {
+  static Future<Directory> _cacheDir() async {
     Directory cacheDir = new Directory(path.join(packageRoot, 'sky_tools', 'cache'));
     if (!await cacheDir.exists()) {
       await cacheDir.create(recursive: true);
@@ -50,7 +50,7 @@ class ArtifactStore {
     return cacheDir;
   }
 
-  Future<Directory> _engineSpecificCacheDir() async {
+  static Future<Directory> _engineSpecificCacheDir() async {
     Directory cacheDir = await _cacheDir();
     // For now, all downloaded artifacts are release mode host binaries so use
     // a path that mirrors a local release build.
@@ -65,11 +65,11 @@ class ArtifactStore {
   }
 
   // Whether the artifact needs to be marked as executable on disk.
-  bool _needsToBeExecutable(Artifact artifact) {
+  static bool _needsToBeExecutable(Artifact artifact) {
     return artifact == Artifact.FlutterCompiler;
   }
 
-  Future<String> getPath(Artifact artifact) async {
+  static Future<String> getPath(Artifact artifact) async {
     Directory cacheDir = await _engineSpecificCacheDir();
 
     String category, name;
@@ -98,13 +98,13 @@ class ArtifactStore {
     return cachedFile.path;
   }
 
-  Future clear() async {
+  static Future clear() async {
     Directory cacheDir = await _cacheDir();
     _logging.fine('Clearing cache directory ${cacheDir.path}');
     await cacheDir.delete(recursive: true);
   }
 
-  Future populate() async {
+  static Future populate() async {
     for (Artifact artifact in Artifact.values) {
       _logging.fine('Populating cache with $artifact');
       await getPath(artifact);

packages/flutter_tools/lib/src/build.dart

@@ -105,8 +105,7 @@ Future _compileSnapshot({
   String snapshotPath
 }) async {
   if (compilerPath == null) {
-    ArtifactStore artifacts = new ArtifactStore(packageRoot);
-    compilerPath = await artifacts.getPath(Artifact.FlutterCompiler);
+    compilerPath = await ArtifactStore.getPath(Artifact.FlutterCompiler);
   }
   ProcessResult result = await Process.run(compilerPath, [
     mainPath,
@@ -135,7 +134,6 @@ class BuildCommand extends Command {
     argParser.addOption('main', defaultsTo: 'lib/main.dart');
     argParser.addOption('manifest');
     argParser.addOption('output-file', abbr: 'o', defaultsTo: 'app.flx');
-    argParser.addOption('package-root', defaultsTo: 'packages');
     argParser.addOption('snapshot', defaultsTo: 'snapshot_blob.bin');
   }
 

packages/flutter_tools/lib/src/cache.dart

@@ -25,14 +25,10 @@ class CacheCommand extends Command {
 class _ClearCommand extends Command {
   final name = 'clear';
   final description = 'Clears all artifacts from the cache.';
-  _ClearCommand() {
-    argParser.addOption('package-root', defaultsTo: 'packages');
-  }
 
   @override
   Future<int> run() async {
-    ArtifactStore artifacts = new ArtifactStore(argResults['package-root']);
-    await artifacts.clear();
+    await ArtifactStore.clear();
     return 0;
   }
 }
@@ -40,14 +36,10 @@ class _ClearCommand extends Command {
 class _PopulateCommand extends Command {
   final name = 'populate';
   final description = 'Populates the cache with all known artifacts.';
-  _PopulateCommand() {
-    argParser.addOption('package-root', defaultsTo: 'packages');
-  }
 
   @override
   Future<int> run() async {
-    ArtifactStore artifacts = new ArtifactStore(argResults['package-root']);
-    await artifacts.populate();
+    await ArtifactStore.populate();
     return 0;
   }
 }

packages/flutter_tools/lib/src/run_mojo.dart

@@ -38,8 +38,8 @@ class RunMojoCommand extends Command {
     return file.absolute.path;
   }
 
-  Future<int> _runAndroid(ArgResults results, String appPath, ArtifactStore artifacts) async {
-    String skyViewerUrl = artifacts.googleStorageUrl('viewer', 'android-arm');
+  Future<int> _runAndroid(ArgResults results, String appPath) async {
+    String skyViewerUrl = ArtifactStore.googleStorageUrl('viewer', 'android-arm');
     String command = await _makePathAbsolute(path.join(results['mojo-path'], 'mojo', 'devtools', 'common', 'mojo_run'));
     String appName = path.basename(appPath);
     String appDir = path.dirname(appPath);
@@ -62,8 +62,8 @@ class RunMojoCommand extends Command {
     return runCommandAndStreamOutput(command, args);
   }
 
-  Future<int> _runLinux(ArgResults results, String appPath, ArtifactStore artifacts) async {
-    String viewerPath = await _makePathAbsolute(await artifacts.getPath(Artifact.SkyViewerMojo));
+  Future<int> _runLinux(ArgResults results, String appPath) async {
+    String viewerPath = await _makePathAbsolute(await ArtifactStore.getPath(Artifact.SkyViewerMojo));
     String mojoBuildType = argResults['mojo-debug'] ? 'Debug' : 'Release';
     String mojoShellPath = await _makePathAbsolute(path.join(results['mojo-path'], 'out', mojoBuildType, 'mojo_shell'));
     List<String> args = [
@@ -84,13 +84,11 @@ class RunMojoCommand extends Command {
       _logging.severe('Cannot specify both --mojo-debug and --mojo-release');
       return 1;
     }
-    String packageRoot = argResults['package-root'];
-    ArtifactStore artifacts = new ArtifactStore(packageRoot);
     String appPath = await _makePathAbsolute(argResults['app']);
     if (argResults['android']) {
-      return _runAndroid(argResults, appPath, artifacts);
+      return _runAndroid(argResults, appPath);
     } else {
-      return _runLinux(argResults, appPath, artifacts);
+      return _runLinux(argResults, appPath);
     }
   }
 }