async_hooksで遊んでみた

test.js

const async_hooks = require('async_hooks')

const map = new Map()

let beforeCount = 0
let afterCount = 0

const hook = async_hooks.createHook({
  init(asyncId, type, triggerAsyncId, resource) {
    const context = map.get(triggerAsyncId)
    if (!context) {
      return
    }
    map.set(asyncId, { ...context })
  },

  before(asyncId) {
    if (beforeCount % 500 === 0) {
      console.log('before', asyncId)
    }
    beforeCount++
  },

  after(asyncId) {
    if (afterCount % 500 === 0) {
      console.log('after', asyncId)
    }
    afterCount++
  },

  promiseResolve(asyncId) {},

  destroy(asyncId) {
    map.delete(asyncId)
  },
})

hook.enable()

function getContext() {
  const asyncId = async_hooks.executionAsyncId()
  console.log('getContext', asyncId)
  return map.get(asyncId)
}

function setContext(context) {
  const asyncId = async_hooks.executionAsyncId()
  map.set(asyncId, context)
}

function dumpContext() {
  console.log(getContext())
}

dumpContext()
setContext({ id: 'test' })
dumpContext()
dumpContext()
dumpContext()

setTimeout(() => {
  const asyncId = async_hooks.executionAsyncId()
  console.log(asyncId)
  dumpContext()
  new Promise((r) => {
    r()
  }).then(() => {
    const asyncId = async_hooks.executionAsyncId()
    console.log(asyncId)
    dumpContext()
  })
})