53 lines
1.4 KiB
JavaScript
53 lines
1.4 KiB
JavaScript
'use strict'
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/**
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* @callback GenerateRequestId
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* @param {Object} req
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* @returns {string}
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*/
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/**
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* @param {string} [requestIdHeader]
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* @param {GenerateRequestId} [optGenReqId]
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* @returns {GenerateRequestId}
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*/
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function reqIdGenFactory (requestIdHeader, optGenReqId) {
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const genReqId = optGenReqId || buildDefaultGenReqId()
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if (requestIdHeader) {
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return buildOptionalHeaderReqId(requestIdHeader, genReqId)
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}
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return genReqId
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}
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function getGenReqId (contextServer, req) {
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return contextServer.genReqId(req)
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}
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function buildDefaultGenReqId () {
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// 2,147,483,647 (2^31 − 1) stands for max SMI value (an internal optimization of V8).
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// With this upper bound, if you'll be generating 1k ids/sec, you're going to hit it in ~25 days.
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// This is very likely to happen in real-world applications, hence the limit is enforced.
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// Growing beyond this value will make the id generation slower and cause a deopt.
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// In the worst cases, it will become a float, losing accuracy.
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const maxInt = 2147483647
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let nextReqId = 0
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return function defaultGenReqId () {
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nextReqId = (nextReqId + 1) & maxInt
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return `req-${nextReqId.toString(36)}`
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}
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}
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function buildOptionalHeaderReqId (requestIdHeader, genReqId) {
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return function (req) {
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return req.headers[requestIdHeader] || genReqId(req)
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}
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}
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module.exports = {
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getGenReqId,
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reqIdGenFactory
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}
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