dd-trace/packages/datadog-instrumentations/src/express-session.js

Datadog APM tracing client for JavaScript

'use strict'

const shimmer = require('../../datadog-shimmer')
const { channel, addHook } = require('./helpers/instrument')

const sessionMiddlewareFinishCh = channel('datadog:express-session:middleware:finish')

function wrapSessionMiddleware (sessionMiddleware) {
  return function wrappedSessionMiddleware (...args) {
    const req = args[0]
    const res = args[1]
    // Mirror next's name/arity so wrapCallback skips its per-call identity rewrite.
    args[2] = shimmer.wrapCallback(args[2], original => function next (_error) {
      if (sessionMiddlewareFinishCh.hasSubscribers) {
        const abortController = new AbortController()

        sessionMiddlewareFinishCh.publish({ req, res, sessionId: req.sessionID, abortController })

        if (abortController.signal.aborted) return
      }

      return original.apply(this, arguments)
    })

    return Reflect.apply(sessionMiddleware, this, args)
  }
}

function wrapSession (session) {
  return function wrappedSession (...args) {
    const sessionMiddleware = session.apply(this, args)

    return shimmer.wrapFunction(sessionMiddleware, wrapSessionMiddleware)
  }
}

addHook({
  name: 'express-session',
  versions: ['>=1.5.0'],
}, session => {
  return shimmer.wrapFunction(session, wrapSession)
})