dart2js: add function coverage tracking in dart2js output, dumpinfo, and

pkg/compiler/tool/coverage_log_server.dart

Index: pkg/compiler/tool/coverage_log_server.dart
diff --git a/pkg/compiler/tool/coverage_log_server.dart b/pkg/compiler/tool/coverage_log_server.dart
new file mode 100644
index 0000000000000000000000000000000000000000..d2e860e46ad259a112835451f74dfc1f766b0f25
--- /dev/null
+++ b/pkg/compiler/tool/coverage_log_server.dart
@@ -0,0 +1,190 @@
+// Copyright (c) 2015, 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.
+
+/// A tool to gather coverage data from an app generated with dart2js.
+/// This tool starts a server that answers to mainly 2 requests:
+///    * a GET request to retrieve the application
+///    * POST requests to record coverage data.
+///
+/// It is intended to be used as follows:
+///    * generate an app by running dart2js with the environment boolean
+///      -DinstrumentForCoverage=true provided to the vm, and the --dump-info
+///      flag provided to dart2js.
+///    * start this server, and proxy requests from your normal frontend
+///      server to this one.
+library compiler.tool.coverage_log_server;
+
+import 'dart:convert';
+import 'dart:io';
+import 'dart:async';
+import 'package:path/path.dart' as path;
+import 'package:args/args.dart';
+import 'package:shelf/shelf.dart' as shelf;
+import 'package:shelf/shelf_io.dart' as shelf;
+
+const _DEFAULT_OUT_TEMPLATE = '<dart2js-out-file>.coverage.json';
+
+main(argv) async {
+  var parser = new ArgParser()
+    ..addOption('port', abbr: 'p', help: 'port number', defaultsTo: "8080")
+    ..addOption('host', help: 'host name (use 0.0.0.0 for all interfaces)',
+        defaultsTo: 'localhost')
+    ..addFlag('help', abbr: 'h', help: 'show this help message',
+        negatable: false)
+    ..addOption('uri-prefix',
+        help: 'uri path prefix that will hit this server. This will be injected'
+              ' into the .js file',
+        defaultsTo: '')
+    ..addOption('out', abbr: 'o', help: 'output log file',
+        defaultsTo: _DEFAULT_OUT_TEMPLATE);
+  var args = parser.parse(argv);
+  if (args['help'] == true || args.rest.isEmpty) {
+    print('usage: dart coverage_logging.dart [options] '
+        '<dart2js-out-file> [<html-file>]');
+    print(parser.usage);
+    exit(1);
+  }
+
+  var jsPath = args.rest[0];
+  var htmlPath = null;
+  if (args.rest.length > 1) {
+    htmlPath = args.rest[1];
+  }
+  var outPath = args['out'];
+  if (outPath == _DEFAULT_OUT_TEMPLATE) outPath = '$jsPath.coverage.json';
+  var server = new _Server(args['host'], int.parse(args['port']), jsPath,
+      htmlPath, outPath, args['uri-prefix']);
+  await server.run();
+}
+
+class _Server {
+  /// Server hostname, typically `localhost`,  but can be `0.0.0.0`.
+  final String hostname;
+
+  /// Port the server will listen to.
+  final int port;
+
+  /// JS file (previously generated by dart2js) to serve.
+  final String jsPath;
+
+  /// HTML file to serve, if any.
+  final String htmlPath;
+
+  /// Contents of jsPath, adjusted to use the appropriate server url.
+  String jsCode;
+
+  /// Location where we'll dump the coverage data.
+  final String outPath;
+
+  /// Uri prefix used on all requests to this server. This will be injected into
+  /// the .js file.
+  final String prefix;
+
+  // TODO(sigmund): add support to load also simple HTML files to test small
+  // simple apps.
+
+  /// Data received so far. The data is just an array of pairs, showing the
+  /// hashCode and name of the element used. This can be later cross-checked
+  /// against dump-info data.
+  Map data = {};
+
+  String get _serializedData => new JsonEncoder.withIndent(' ').convert(data);
+
+  _Server(this.hostname, this.port, String jsPath, this.htmlPath,
+      this.outPath, String prefix)
+      : jsPath = jsPath,
+        jsCode = _adjustRequestUrl(new File(jsPath).readAsStringSync(), prefix),
+        prefix = _normalize(prefix);
+
+  run() async {
+    await shelf.serve(_handler, hostname, port);
+    var urlBase = "http://$hostname:$port${prefix == '' ? '/' : '/$prefix/'}";
+    var htmlFilename = htmlPath == null ? '' : path.basename(htmlPath);
+    print("Server is listening\n"
+        "  - html page: $urlBase$htmlFilename\n"
+        "  - js code: $urlBase${path.basename(jsPath)}\n"
+        "  - coverage reporting: ${urlBase}coverage\n");
+  }
+
+  _expectedPath(String tail) => prefix == '' ? tail : '$prefix/$tail';
+
+  _handler(shelf.Request request) async {
+    var urlPath = request.url.path;
+    print('received request: $urlPath');
+    var baseJsName = path.basename(jsPath);
+    var baseHtmlName = htmlPath == null ? '' : path.basename(htmlPath);
+
+    // Serve an HTML file at the default prefix, or a path matching the HTML
+    // file name
+    if (urlPath == prefix || urlPath == '$prefix/'
+        || urlPath == _expectedPath(baseHtmlName)) {
+      var contents = htmlPath == null
+          ? '<html><script src="$baseJsName"></script>'
+          : await new File(htmlPath).readAsString();
+      return new shelf.Response.ok(contents, headers: HTML_HEADERS);
+    }
+
+    if (urlPath == _expectedPath(baseJsName)) {
+      return new shelf.Response.ok(jsCode, headers: JS_HEADERS);
+    }
+
+    // Handle POST requests to record coverage data, and GET requests to display
+    // the currently coverage resutls.
+    if (urlPath == _expectedPath('coverage')) {
+      if (request.method == 'GET') {
+        return new shelf.Response.ok(_serializedData, headers: TEXT_HEADERS);
+      }
+
+      if (request.method == 'POST') {
+        _record(JSON.decode(await request.readAsString()));
+        return new shelf.Response.ok("Thanks!");
+      }
+    }
+
+    // Any other request is not supported.
+    return new shelf.Response.notFound('Not found: "$urlPath"');
+  }
+
+  _record(List entries) {
+    for (var entry in entries) {
+      var id = entry[0];
+      data.putIfAbsent('$id', () => {'name': entry[1], 'count': 0});
+      data['$id']['count']++;
+    }
+    _enqueueSave();
+  }
+
+  bool _savePending = false;
+  int _total = 0;
+  _enqueueSave() async {
+    if (!_savePending) {
+      _savePending = true;
+      await new Future.delayed(new Duration(seconds: 3));
+      await new File(outPath).writeAsString(_serializedData);
+      var diff = data.length - _total;
+      print(diff ? ' - no new element covered'
+          : ' - $diff new elements covered');
+      _savePending = false;
+      _total = data.length;
+    }
+  }
+}
+
+/// Removes leading and trailing slashes of [uriPath].
+_normalize(String uriPath) {
+  if (uriPath.startsWith('/')) uriPath = uriPath.substring(1);
+  if (uriPath.endsWith('/')) uriPath = uriPath.substring(0, uriPath.length - 1);
+  return uriPath;
+}
+
+_adjustRequestUrl(String code, String prefix) {
+  var newUrl = prefix == '' ? 'coverage' : '$prefix/coverage';
+  return code.replaceFirst(
+      '"/coverage_uri_to_amend_by_server"',
+      '"/$newUrl" /*url-prefix updated!*/');
+}
+
+const HTML_HEADERS = const {'content-type': 'text/html'};
+const JS_HEADERS = const {'content-type': 'text/javascript'};
+const TEXT_HEADERS = const {'content-type': 'text/plain'};