Add a simple benchmark for analysis and error reporting.

pkg/analyzer/benchmark/errors_in_all_libraries.dart

+#!/usr/bin/env dart
+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Resolves this library and everything it transitively imports and generates
+/// errors in all of those libraries. Does this in an infinite loop, starting
+/// from scratch each time, to show how VM warm-up affects things and to make
+/// it easier to connect to this with observatory.
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/java_io.dart';
+import 'package:analyzer/src/generated/sdk_io.dart' show DirectoryBasedDartSdk;
+import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/generated/source_io.dart';
+
+void main(List<String> args) {
+  JavaSystemIO.setProperty(
+      "com.google.dart.sdk",
+      p.normalize(
+          p.join(p.dirname(p.fromUri(Platform.script)), "../../../sdk")));
+
+  // Assumes you have run "pub get" in the analyzer directory itself and uses
+  // that "packages" directory as its package root.
+  var packageRoot =
+      p.normalize(p.join(p.dirname(p.fromUri(Platform.script)), "packages"));
+
+  var best = new Duration(days: 1);
+  while (true) {
+    var start = new DateTime.now();
+    AnalysisEngine.instance.clearCaches();
+
+    var context = AnalysisEngine.instance.createAnalysisContext();
+    context.sourceFactory = new SourceFactory([
+      new DartUriResolver(DirectoryBasedDartSdk.defaultSdk),
+      new FileUriResolver(),
+      new PackageUriResolver([new JavaFile(packageRoot)])
+    ]);
+
+    context.analysisOptions.strongMode = true;
+    context.analysisOptions.strongModeHints = true;
+
+    var mainSource =
+        new FileBasedSource(new JavaFile(p.fromUri(Platform.script)));
+    context.applyChanges(new ChangeSet()..addedSource(mainSource));
+
+    var initialLibrary =
+        context.resolveCompilationUnit2(mainSource, mainSource);
+
+    // Walk all of the transitively referenced libraries and compute errors.
+    var errorCount = 0;
+    var allLibraries = _reachableLibraries(initialLibrary.element.library);
+    for (var lib in allLibraries) {
+      for (var unit in lib.units) {
+        var source = unit.source;
+
+        // Skip core libraries.
+        if (source.uri.scheme == 'dart') continue;
+
+        var librarySource = context.getLibrariesContaining(source).single;
+        context.resolveCompilationUnit2(source, librarySource);
+        errorCount += context.computeErrors(source).length;
+      }
+    }
+
+    var elapsed = new DateTime.now().difference(start);
+    print("$elapsed : $errorCount errors ${elapsed < best ? "(best)" : ""}");
+    if (elapsed < best) best = elapsed;
+  }
+}
+
+/// Returns all libraries transitively imported or exported from [start].
+List<LibraryElement> _reachableLibraries(LibraryElement start) {
+  var results = <LibraryElement>[];
+  var seen = new Set();
+  void find(LibraryElement lib) {
+    if (seen.contains(lib)) return;
+    seen.add(lib);
+    results.add(lib);
+    lib.importedLibraries.forEach(find);
+    lib.exportedLibraries.forEach(find);
+  }
+  find(start);
+  return results;
+}