const { createHook, AsyncResource, executionAsyncId } = require('async_hooks')

const hook = createHook({
 init (asyncId, type, triggerAsyncId, resource) {},
 before (asyncId) {},
 after (asyncId) {},
 destroy (asyncId) {}
})
hook.enable()

function fn () {
 console.log(executionAsyncId())
}

const asyncResource = new AsyncResource('demo')
asyncResource.run(fn)
asyncResource.run(fn)
asyncResource.emitDestroy()

const http = require('http')
const { createHook, executionAsyncId } = require('async_hooks')
const fs = require('fs')

// 追蹤調(diào)用鏈并創(chuàng)建調(diào)用鏈存儲(chǔ)對(duì)象
const cache = {}
const hook = createHook({
 init (asyncId, type, triggerAsyncId, resource) {
  if (type === 'TickObject') return
  // 由于在 Node.js 中 console.log 也是異步行為，會(huì)導(dǎo)致觸發(fā) init 鉤子，所以我們只能通過同步方法記錄日志
  fs.appendFileSync('log.out', `init ${type}(${asyncId}: trigger: ${triggerAsyncId})\n`);
  // 判斷調(diào)用鏈存儲(chǔ)對(duì)象是否已經(jīng)初始化
  if (!cache[triggerAsyncId]) {
   cache[triggerAsyncId] = {}
  }
  // 將父節(jié)點(diǎn)的存儲(chǔ)與當(dāng)前異步資源通過引用共享
  cache[asyncId] = cache[triggerAsyncId]
 }
})
hook.enable()

// 改寫 http
const httpRequest = http.request
http.request = (options, callback) => {
 const client = httpRequest(options, callback)
 // 獲取當(dāng)前請(qǐng)求所屬異步資源對(duì)應(yīng)存儲(chǔ)的 request-id 寫入 header
 const requestId = cache[executionAsyncId()].requestId
 console.log('cache', cache[executionAsyncId()])
 client.setHeader('request-id', requestId)

 return client
}

function timeout () {
 return new Promise((resolve, reject) => {
  setTimeout(resolve, Math.random() * 1000)
 })
}
// 創(chuàng)建服務(wù)
http
 .createServer(async (req, res) => {
  // 獲取當(dāng)前請(qǐng)求的 request-id 寫入存儲(chǔ)
  cache[executionAsyncId()].requestId = req.headers['request-id']
  // 模擬一些其他耗時(shí)操作
  await timeout()
  // 發(fā)送一個(gè)請(qǐng)求
  http.request('http://www.baidu.com', (res) => {})
  res.write('hello\n')
  res.end()
 })
 .listen(3000)

  if (!cache[triggerAsyncId]) {
   cache[triggerAsyncId] = {
    id: triggerAsyncId
   }
  }

function timeout () {
 return new Promise((resolve, reject) => {
  setTimeout(resolve, [1000, 5000].pop())
 })
}

const http = require('http')
const { createHook, executionAsyncId } = require('async_hooks')
const fs = require('fs')
const cache = {}

const httpRequest = http.request
http.request = (options, callback) => {
 const client = httpRequest(options, callback)
 const requestId = cache[executionAsyncId()].requestId
 console.log('cache', cache[executionAsyncId()])
 client.setHeader('request-id', requestId)

 return client
}

// 將存儲(chǔ)的初始化提取為一個(gè)獨(dú)立的方法
async function cacheInit (callback) {
 // 利用 await 操作使得 await 后的代碼進(jìn)入一個(gè)全新的異步上下文
 await Promise.resolve()
 cache[executionAsyncId()] = {}
 // 使用 callback 執(zhí)行的方式，使得后續(xù)操作都屬于這個(gè)新的異步上下文
 return callback()
}

const hook = createHook({
 init (asyncId, type, triggerAsyncId, resource) {
  if (!cache[triggerAsyncId]) {
   // init hook 不再進(jìn)行初始化
   return fs.appendFileSync('log.out', `未使用 cacheInit 方法進(jìn)行初始化`)
  }
  cache[asyncId] = cache[triggerAsyncId]
 }
})
hook.enable()

function timeout () {
 return new Promise((resolve, reject) => {
  setTimeout(resolve, [1000, 5000].pop())
 })
}

http
.createServer(async (req, res) => {
 // 將后續(xù)操作作為 callback 傳入 cacheInit
 await cacheInit(async function fn() {
  cache[executionAsyncId()].requestId = req.headers['request-id']
  await timeout()
  http.request('http://www.baidu.com', (res) => {})
  res.write('hello\n')
  res.end()
 })
})
.listen(3000)

async function middleware (ctx, next) {
 await Promise.resolve()
 cache[executionAsyncId()] = {}
 return next()
}

const { AsyncLocalStorage } = require('async_hooks')
// 直接創(chuàng)建一個(gè) asyncLocalStorage 存儲(chǔ)實(shí)例，不再需要管理 async 生命周期鉤子
const asyncLocalStorage = new AsyncLocalStorage()
const storage = {
 enable (callback) {
  // 使用 run 方法創(chuàng)建全新的存儲(chǔ)，且需要讓后續(xù)操作作為 run 方法的回調(diào)執(zhí)行，以使用全新的異步資源上下文
  asyncLocalStorage.run({}, callback)
 },
 get (key) {
  return asyncLocalStorage.getStore()[key]
 },
 set (key, value) {
  asyncLocalStorage.getStore()[key] = value
 }
}

// 改寫 http
const httpRequest = http.request
http.request = (options, callback) => {
 const client = httpRequest(options, callback)
 // 獲取異步資源存儲(chǔ)的 request-id 寫入 header
 client.setHeader('request-id', storage.get('requestId'))

 return client
}

// 使用
http
 .createServer((req, res) => {
  storage.enable(async function () {
   // 獲取當(dāng)前請(qǐng)求的 request-id 寫入存儲(chǔ)
   storage.set('requestId', req.headers['request-id'])
   http.request('http://www.baidu.com', (res) => {})
   res.write('hello\n')
   res.end()
  })
 })
 .listen(3000)