104 lines
2.5 KiB
JavaScript
104 lines
2.5 KiB
JavaScript
// Copyright 2011 The Closure Library Authors. All Rights Reserved.
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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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* @fileoverview Utility class to manage the mathematics behind computing an
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* exponential backoff model. Given an initial backoff value and a maximum
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* backoff value, every call to backoff() will double the value until maximum
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* backoff value is reached.
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*
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*/
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goog.provide('goog.math.ExponentialBackoff');
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goog.require('goog.asserts');
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/**
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* @constructor
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*
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* @param {number} initialValue The initial backoff value.
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* @param {number} maxValue The maximum backoff value.
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*/
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goog.math.ExponentialBackoff = function(initialValue, maxValue) {
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goog.asserts.assert(initialValue > 0,
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'Initial value must be greater than zero.');
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goog.asserts.assert(maxValue >= initialValue,
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'Max value should be at least as large as initial value.');
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/**
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* @type {number}
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* @private
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*/
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this.initialValue_ = initialValue;
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/**
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* @type {number}
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* @private
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*/
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this.maxValue_ = maxValue;
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/**
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* The current backoff value.
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* @type {number}
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* @private
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*/
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this.currValue_ = initialValue;
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};
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/**
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* The number of backoffs that have happened.
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* @type {number}
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* @private
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*/
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goog.math.ExponentialBackoff.prototype.currCount_ = 0;
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/**
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* Resets the backoff value to its initial value.
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*/
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goog.math.ExponentialBackoff.prototype.reset = function() {
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this.currValue_ = this.initialValue_;
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this.currCount_ = 0;
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};
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/**
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* @return {number} The current backoff value.
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*/
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goog.math.ExponentialBackoff.prototype.getValue = function() {
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return this.currValue_;
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};
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/**
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* @return {number} The number of times this class has backed off.
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*/
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goog.math.ExponentialBackoff.prototype.getBackoffCount = function() {
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return this.currCount_;
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};
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/**
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* Initiates a backoff.
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*/
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goog.math.ExponentialBackoff.prototype.backoff = function() {
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this.currValue_ = Math.min(this.maxValue_, this.currValue_ * 2);
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this.currCount_++;
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};
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