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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 | |
| 26 * @type Object.<string, Array.<number>> | |
| 27 */ | |
| 28 this.valueLists_ = {}; | |
| 29 | |
| 30 /** | |
| 31 * The first time, after this object was most recently initialized or emptied, | |
| 32 * at which a value was added to this object. | |
| 33 * @private | |
| 34 * @type {?number} | |
| 35 */ | |
| 36 this.timeOfFirstValue_ = null; | |
| 37 }; | |
| 38 | |
| 39 /** | |
| 40 * Adds values to this object. | |
| 41 * | |
| 42 * @param {Object.<string, number>} newValues | |
| 43 */ | |
| 44 remoting.StatsAccumulator.prototype.add = function(newValues) { | |
| 45 for (var key in newValues) { | |
| 46 this.getValueList(key).push(newValues[key]); | |
| 47 } | |
| 48 if (!this.timeOfFirstValue_) { | |
| 49 this.timeOfFirstValue_ = new Date().getTime(); | |
| 50 } | |
| 51 }; | |
| 52 | |
| 53 /** | |
| 54 * Empties this object. | |
| 55 */ | |
| 56 remoting.StatsAccumulator.prototype.empty = function() { | |
| 57 this.valueLists_ = {}; | |
| 58 this.timeOfFirstValue_ = null; | |
| 59 }; | |
| 60 | |
| 61 /** | |
| 62 * Gets the number of milliseconds since the first value was added to this | |
| 63 * object, after this object was most recently initialized or emptied. | |
| 64 * | |
| 65 * @return {number} milliseconds since the first value | |
| 66 */ | |
| 67 remoting.StatsAccumulator.prototype.getTimeSinceFirstValue = function() { | |
| 68 if (!this.timeOfFirstValue_) { | |
| 69 return 0; | |
| 70 } | |
| 71 return new Date().getTime() - this.timeOfFirstValue_; | |
| 72 }; | |
| 73 | |
| 74 /** | |
| 75 * Calculates the mean of the values for a given key. | |
| 76 * | |
| 77 * @param {string} key | |
| 78 * @return {number} the mean of the values for that key | |
| 79 */ | |
| 80 remoting.StatsAccumulator.prototype.calcMean = function(key) { | |
| 81 /** | |
| 82 * @param {Array.<number>} values | |
| 83 * @return {number} | |
| 84 */ | |
| 85 var calcMean = function(values) { | |
| 86 if (values.length == 0) { | |
| 87 return 0.0; | |
| 88 } | |
| 89 var sum = 0; | |
| 90 for (var i = 0; i < values.length; i++) { | |
| 91 sum += values[i]; | |
| 92 } | |
| 93 return sum / values.length; | |
| 94 }; | |
| 95 return this.map(key, calcMean); | |
| 96 }; | |
| 97 | |
| 98 /** | |
| 99 * Applies a given map to the list of values for a given key. | |
| 100 * | |
| 101 * @param {string} key | |
| 102 * @param {function(Array.<number>): number} map | |
| 103 * @return {number} the result of applying that map to the list of values for | |
| 104 * that key | |
| 105 */ | |
| 106 remoting.StatsAccumulator.prototype.map = function(key, map) { | |
| 107 return map(this.getValueList(key)); | |
| 108 }; | |
| 109 | |
| 110 /** | |
| 111 * Gets the list of values for a given key. | |
| 112 * If this object contains no values for that key, then this routine creates | |
| 113 * an empty list, stores it in this object, and returns it. | |
| 114 * | |
| 115 * @private | |
| 116 * @param {string} key | |
| 117 * @return {Array.<number>} the list of values for that key | |
| 118 */ | |
| 119 remoting.StatsAccumulator.prototype.getValueList = function(key) { | |
| 120 var valueList = this.valueLists_[key]; | |
| 121 if (!valueList) { | |
| 122 valueList = []; | |
| 123 this.valueLists_[key] = valueList; | |
| 124 } | |
| 125 return valueList; | |
| 126 }; | |
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