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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 /** | |
6 * @fileoverview | |
7 * The webapp reads the plugin's connection statistics frequently (once per | |
8 * second). It logs statistics to the server less frequently, to keep | |
9 * bandwidth and storage costs down. This class bridges that gap, by | |
10 * accumulating high-frequency numeric data, and providing statistics | |
11 * summarising that data. | |
12 */ | |
13 | |
14 'use strict'; | |
15 | |
16 /** @suppress {duplicate} */ | |
17 var remoting = remoting || {}; | |
18 | |
19 /** | |
20 * @constructor | |
21 */ | |
22 remoting.StatsAccumulator = function() { | |
23 /** | |
24 * A map from names to lists of values. | |
25 * @private {Object<string, Array<number>>} | |
26 */ | |
27 this.valueLists_ = {}; | |
28 | |
29 /** | |
30 * The first time, after this object was most recently initialized or emptied, | |
31 * at which a value was added to this object. | |
32 * @private {?number} | |
33 */ | |
34 this.timeOfFirstValue_ = null; | |
35 }; | |
36 | |
37 /** | |
38 * Adds values to this object. | |
39 * | |
40 * @param {Object<string, number>} newValues | |
41 */ | |
42 remoting.StatsAccumulator.prototype.add = function(newValues) { | |
43 for (var key in newValues) { | |
44 this.getValueList(key).push(newValues[key]); | |
45 } | |
46 if (!this.timeOfFirstValue_) { | |
47 this.timeOfFirstValue_ = new Date().getTime(); | |
48 } | |
49 }; | |
50 | |
51 /** | |
52 * Empties this object. | |
53 */ | |
54 remoting.StatsAccumulator.prototype.empty = function() { | |
55 this.valueLists_ = {}; | |
56 this.timeOfFirstValue_ = null; | |
57 }; | |
58 | |
59 /** | |
60 * Gets the number of milliseconds since the first value was added to this | |
61 * object, after this object was most recently initialized or emptied. | |
62 * | |
63 * @return {number} milliseconds since the first value | |
64 */ | |
65 remoting.StatsAccumulator.prototype.getTimeSinceFirstValue = function() { | |
66 if (!this.timeOfFirstValue_) { | |
67 return 0; | |
68 } | |
69 return new Date().getTime() - this.timeOfFirstValue_; | |
70 }; | |
71 | |
72 /** | |
73 * Calculates the mean of the values for a given key. | |
74 * | |
75 * @param {string} key | |
76 * @return {number} the mean of the values for that key | |
77 */ | |
78 remoting.StatsAccumulator.prototype.calcMean = function(key) { | |
79 /** | |
80 * @param {Array<number>} values | |
81 * @return {number} | |
82 */ | |
83 var calcMean = function(values) { | |
84 if (values.length == 0) { | |
85 return 0.0; | |
86 } | |
87 var sum = 0; | |
88 for (var i = 0; i < values.length; i++) { | |
89 sum += values[i]; | |
90 } | |
91 return sum / values.length; | |
92 }; | |
93 return this.map(key, calcMean); | |
94 }; | |
95 | |
96 /** | |
97 * Applies a given map to the list of values for a given key. | |
98 * | |
99 * @param {string} key | |
100 * @param {function(Array<number>): number} map | |
101 * @return {number} the result of applying that map to the list of values for | |
102 * that key | |
103 */ | |
104 remoting.StatsAccumulator.prototype.map = function(key, map) { | |
105 return map(this.getValueList(key)); | |
106 }; | |
107 | |
108 /** | |
109 * Gets the list of values for a given key. | |
110 * If this object contains no values for that key, then this routine creates | |
111 * an empty list, stores it in this object, and returns it. | |
112 * | |
113 * @private | |
114 * @param {string} key | |
115 * @return {Array<number>} the list of values for that key | |
116 */ | |
117 remoting.StatsAccumulator.prototype.getValueList = function(key) { | |
118 var valueList = this.valueLists_[key]; | |
119 if (!valueList) { | |
120 valueList = []; | |
121 this.valueLists_[key] = valueList; | |
122 } | |
123 return valueList; | |
124 }; | |
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