Roll Observatory packages and add a roll script

usage/lib/src/usage_impl.dart

-// Copyright (c) 2014, 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.
-
-library usage_impl;
-
-import 'dart:async';
-import 'dart:math' as math;
-
-import 'uuid.dart';
-import '../usage.dart';
-
-final int _MAX_EXCEPTION_LENGTH = 100;
-
-String postEncode(Map<String, dynamic> map) {
-  // &foo=bar
-  return map.keys.map((key) {
-    String value = '${map[key]}';
-    return "${key}=${Uri.encodeComponent(value)}";
-  }).join('&');
-}
-
-/**
- * A throttling algorithim. This models the throttling after a bucket with
- * water dripping into it at the rate of 1 drop per second. If the bucket has
- * water when an operation is requested, 1 drop of water is removed and the
- * operation is performed. If not the operation is skipped. This algorithim
- * lets operations be peformed in bursts without throttling, but holds the
- * overall average rate of operations to 1 per second.
- */
-class ThrottlingBucket {
-  final int startingCount;
-  int drops;
-  int _lastReplenish;
-
-  ThrottlingBucket(this.startingCount) {
-    drops = startingCount;
-    _lastReplenish = new DateTime.now().millisecondsSinceEpoch;
-  }
-
-  bool removeDrop() {
-    _checkReplenish();
-
-    if (drops <= 0) {
-      return false;
-    } else {
-      drops--;
-      return true;
-    }
-  }
-
-  void _checkReplenish() {
-    int now = new DateTime.now().millisecondsSinceEpoch;
-
-    if (_lastReplenish + 1000 >= now) {
-      int inc = (now - _lastReplenish) ~/ 1000;
-      drops = math.min(drops + inc, startingCount);
-      _lastReplenish += (1000 * inc);
-    }
-  }
-}
-
-abstract class AnalyticsImpl extends Analytics {
-  static const String _GA_URL = 'https://www.google-analytics.com/collect';
-
-  /// Tracking ID / Property ID.
-  final String trackingId;
-
-  final PersistentProperties properties;
-  final PostHandler postHandler;
-
-  final ThrottlingBucket _bucket = new ThrottlingBucket(20);
-  final Map<String, dynamic> _variableMap = {};
-
-  final List<Future> _futures = [];
-
-  AnalyticsImpl(this.trackingId, this.properties, this.postHandler,
-      {String applicationName, String applicationVersion}) {
-    assert(trackingId != null);
-
-    if (applicationName != null) setSessionValue('an', applicationName);
-    if (applicationVersion != null) setSessionValue('av', applicationVersion);
-  }
-
-  bool get optIn => properties['optIn'] == true;
-
-  set optIn(bool value) {
-    properties['optIn'] = value;
-  }
-
-  bool get hasSetOptIn => properties['optIn'] != null;
-
-  Future sendScreenView(String viewName) {
-    Map args = {'cd': viewName};
-    return _sendPayload('screenview', args);
-  }
-
-  Future sendEvent(String category, String action, {String label, int value}) {
-    if (!optIn) return new Future.value();
-
-    Map args = {'ec': category, 'ea': action};
-    if (label != null) args['el'] = label;
-    if (value != null) args['ev'] = value;
-    return _sendPayload('event', args);
-  }
-
-  Future sendSocial(String network, String action, String target) {
-    if (!optIn) return new Future.value();
-
-    Map args = {'sn': network, 'sa': action, 'st': target};
-    return _sendPayload('social', args);
-  }
-
-  Future sendTiming(String variableName, int time, {String category,
-        String label}) {
-    if (!optIn) return new Future.value();
-
-    Map args = {'utv': variableName, 'utt': time};
-    if (label != null) args['utl'] = label;
-    if (category != null) args['utc'] = category;
-    return _sendPayload('timing', args);
-  }
-
-  AnalyticsTimer startTimer(String variableName, {String category, String label}) {
-    return new AnalyticsTimer(this,
-        variableName, category: category, label: label);
-  }
-
-  Future sendException(String description, {bool fatal}) {
-    if (!optIn) return new Future.value();
-
-    // In order to ensure that the client of this API is not sending any PII
-    // data, we strip out any stack trace that may reference a path on the
-    // user's drive (file:/...).
-    if (description.contains('file:/')) {
-      description = description.substring(0, description.indexOf('file:/'));
-    }
-
-    if (description != null && description.length > _MAX_EXCEPTION_LENGTH) {
-      description = description.substring(0, _MAX_EXCEPTION_LENGTH);
-    }
-
-    Map args = {'exd': description};
-    if (fatal != null && fatal) args['exf'] = '1';
-    return _sendPayload('exception', args);
-  }
-
-  void setSessionValue(String param, dynamic value) {
-    if (value == null) {
-      _variableMap.remove(param);
-    } else {
-      _variableMap[param] = value;
-    }
-  }
-
-  Future waitForLastPing({Duration timeout}) {
-    Future f = Future.wait(_futures).catchError((e) => null);
-
-    if (timeout != null) {
-      f = f.timeout(timeout, onTimeout: () => null);
-    }
-
-    return f;
-  }
-
-  /**
-   * Anonymous Client ID. The value of this field should be a random UUID v4.
-   */
-  String get _clientId => properties['clientId'];
-
-  void _initClientId() {
-    if (_clientId == null) {
-      properties['clientId'] = new Uuid().generateV4();
-    }
-  }
-
-  // Valid values for [hitType] are: 'pageview', 'screenview', 'event',
-  // 'transaction', 'item', 'social', 'exception', and 'timing'.
-  Future _sendPayload(String hitType, Map args) {
-    if (_bucket.removeDrop()) {
-      _initClientId();
-
-      _variableMap.forEach((key, value) {
-        args[key] = value;
-      });
-
-      args['v'] = '1'; // protocol version
-      args['tid'] = trackingId;
-      args['cid'] = _clientId;
-      args['t'] = hitType;
-
-      return _recordFuture(postHandler.sendPost(_GA_URL, args));
-    } else {
-      return new Future.value();
-    }
-  }
-
-  Future _recordFuture(Future f) {
-    _futures.add(f);
-    return f.whenComplete(() => _futures.remove(f));
-  }
-}
-
-/**
- * A persistent key/value store. An [AnalyticsImpl] instance expects to have one
- * of these injected into it. There are default implementations for `dart:io`
- * and `dart:html` clients.
- *
- * The [name] paramater is used to uniquely store these properties on disk /
- * persistent storage.
- */
-abstract class PersistentProperties {
-  final String name;
-
-  PersistentProperties(this.name);
-
-  dynamic operator[](String key);
-  void operator[]=(String key, dynamic value);
-}
-
-/**
- * A utility class to perform HTTP POSTs. An [AnalyticsImpl] instance expects to
- * have one of these injected into it. There are default implementations for
- * `dart:io` and `dart:html` clients.
- *
- * The POST information should be sent on a best-effort basis. The `Future` from
- * [sendPost] should complete when the operation is finished, but failures to
- * send the information should be silent.
- */
-abstract class PostHandler {
-  Future sendPost(String url, Map<String, String> parameters);
-}