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https://github.com/clusterio/clusterio.git
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Hornwitser
bfe119eaa3
Move all functions and classes currently available through lib/name and libName to be under a single flat namespace in lib. This make reorganising the lib namespace much simpler as the location of symbols can move without breaking the consumers of lib. The multi-entrypoint design was already problematic for the web plugin system which couldn't effectively use it due to how webpack's shared module system is awkward to set up with multiple entrypoints per package.
86 lines
2.7 KiB
JavaScript
86 lines
2.7 KiB
JavaScript
"use strict";
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/**
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* Helper class for implementing the exponential backoff algorithm
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*
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* Provides a convenient interface for implementing an exponential backoff
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* when reconnecting or resending in a distributed network.
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*
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* Once instantiated the delay method will return the next interval to wait
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* for in milliseconds before making another attempt. For each attempt the
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* delay chosen is a random value between 0 and the current maximum delay
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* wwhich starts at a value of 2 * `base` and doubles for ever attempt up to
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* the passed value of `max`. The value for the delay will reset back to
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* `base` if more time than the value for `reset` has passed between two
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* invocations of delay.
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*
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* @alias module:lib.ExponentialBackoff
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*/
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class ExponentialBackoff {
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/**
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* Construct ExponentialBackoff helper
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*
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* The options passed may also be modified on the instance at runtime.
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*
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* @param {object=} options -
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* Options for this exponential backoff helper
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* @param {number=} [options.base=1] -
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* Base delay in seconds. The first delay will on average be this
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* long, but can be anywhere between 0 and 2 times this value.
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* @param {number=} [options.max=60] -
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* Maximum delay in seconds. A delay will not take more than this
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* value.
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* @param {number=} [options.reset=2*max] -
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* Time in seconds between two invocations of delay which will cause
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* it to start over with `base` instead of doubling.
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*/
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constructor(options = {}) {
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/**
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* Base delay in seconds. The first delay will on average be this
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* long, but can be anywhere between 0 and 2 times this value.
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* @type {number}
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*/
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this.base = options.base || 1;
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/**
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* Maximum delay in seconds. A delay will not take more than this
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* value.
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* @type {number}
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*/
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this.max = options.max || 60;
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/**
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* Time in seconds between two invocations of delay which will cause
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* it to start over with `base` instead of doubling.
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* @type {number}
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*/
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this.reset = options.reset || 2 * this.max;
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this._exp = 0;
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this._lastInvocationTime = Date.now();
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}
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/**
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* Compute the next delay to wait
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*
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* Returns the next delay to wait according to the exponential backoff
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* algorithm. This is a value between 0 and min(2 * options.base *
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* 2<sup>retries</sup>, optinos.max).
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*
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* @returns {number} time in milliseconds to wait.
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*/
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delay() {
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let invocationTime = Date.now();
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let interval = (invocationTime - this._lastInvocationTime) / 1000;
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this._lastInvocationTime = invocationTime;
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if (interval > this.reset) {
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this._exp = 0;
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}
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this._exp = Math.min(this._exp + 1, Math.log2(this.max));
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return Math.random() * this.base * 2 ** this._exp * 1000;
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}
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}
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module.exports = ExponentialBackoff;
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