mirror of
https://github.com/shaka-project/shaka-player.git
synced 2026-06-20 16:57:25 +03:00
Joey Parrish
4cc4e96dbd
* Updates all Copyright years to 2015. * Adds licenses annotations to all JS. * Makes all licenses identical to avoid repeated appearance in the compiled output. * Drops fileoverview annotations, which do not affect docs output. * The linter still requires fileoverview on externs. This patch required a newer closure compiler, since the previous version we used had a bug regarding license annotations that caused the license comment block to appear in the output once per file regardless of uniqueness. Change-Id: I2e9272db680cba7ecc4613d97f1d3a94ac2244cc
78 lines
1.8 KiB
JavaScript
78 lines
1.8 KiB
JavaScript
/**
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* @license
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* Copyright 2015 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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goog.provide('shaka.util.EWMA');
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goog.require('shaka.asserts');
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/**
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* Computes an exponentionally-weighted moving average.
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*
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* @param {number} halfLife About half of the estimated value will be from the
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* last |halfLife| samples by weight.
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* @struct
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* @constructor
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*/
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shaka.util.EWMA = function(halfLife) {
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shaka.asserts.assert(halfLife > 0);
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/**
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* Larger values of alpha expire historical data more slowly.
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* @private {number}
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*/
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this.alpha_ = Math.exp(Math.log(0.5) / halfLife);
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/** @private {number} */
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this.estimate_ = 0;
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/** @private {number} */
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this.totalWeight_ = 0;
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};
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/**
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* Takes a sample.
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*
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* @param {number} weight
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* @param {number} value
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*/
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shaka.util.EWMA.prototype.sample = function(weight, value) {
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var adjAlpha = Math.pow(this.alpha_, weight);
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this.estimate_ = value * (1 - adjAlpha) + adjAlpha * this.estimate_;
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this.totalWeight_ += weight;
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};
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/**
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* @return {number}
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*/
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shaka.util.EWMA.prototype.getTotalWeight = function() {
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return this.totalWeight_;
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};
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/**
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* @return {number}
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*/
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shaka.util.EWMA.prototype.getEstimate = function() {
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var zeroFactor = 1 - Math.pow(this.alpha_, this.totalWeight_);
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return this.estimate_ / zeroFactor;
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};
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