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header-processing.js
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header-processing.js
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/*
* Copyright 2020 New Relic Corporation. All rights reserved.
* SPDX-License-Identifier: Apache-2.0
*/
'use strict'
const REQUEST_START_HEADER = 'x-request-start'
const QUEUE_HEADER = 'x-queue-start'
const CONTENT_LENGTH_REGEX = /^Content-Length$/i
/**
* Extracts queue time from the incoming request headers.
*
* Queue time is provided by certain providers by stamping the request
* header with the time the request arrived at the router.
*
* @param {*} logger
* @param {*} requestHeaders
*/
function getQueueTime(logger, requestHeaders) {
const headerValue = requestHeaders[REQUEST_START_HEADER] || requestHeaders[QUEUE_HEADER]
if (!headerValue) {
return null
}
const split = headerValue.split('=')
const rawQueueTime = split.length > 1 ? split[1] : headerValue
const parsedQueueTime = parseFloat(rawQueueTime)
if (isNaN(parsedQueueTime)) {
logger.warn('Queue time header parsed as NaN. See trace level log for value.')
// This header can hold up to 4096 bytes which could quickly fill up logs.
// Do not log a level higher than debug.
logger.trace('Queue time: %s', rawQueueTime)
return null
}
return convertUnit(parsedQueueTime)
}
function convertUnit(time) {
let convertedTime = time
if (convertedTime > 1e18) {
// nano seconds
convertedTime = convertedTime / 1e6
} else if (convertedTime > 1e15) {
// micro seconds
convertedTime = convertedTime / 1e3
} else if (convertedTime < 1e12) {
// seconds
convertedTime = convertedTime * 1e3
}
return convertedTime
}
/**
* Returns the value of the Content-Length header
*
* If no header is found, returns -1
*
* @param {*} headers
*/
function getContentLengthFromHeaders(headers) {
const contentLength = -1
for (const [headerName, headerValue] of Object.entries(headers)) {
if (CONTENT_LENGTH_REGEX.test(headerName)) {
return headerValue
}
}
return contentLength
}
module.exports = {
getQueueTime,
getContentLengthFromHeaders
}