print-leaked-events.js

'use strict'

const asyncHooks = require('async_hooks')

const asyncIds = new Set()

const asyncHook = asyncHooks.createHook({
  init (asyncId, type, triggerAsyncId, resource) {
    const eid = asyncHooks.executionAsyncId()
    process._rawDebug(`${type}(${asyncId}): trigger: ${triggerAsyncId} execution: ${eid}`, resource)
  },
  before (asyncId) {
    process._rawDebug(`before(${asyncId})`)
    asyncIds.add(asyncId)
  },
  after (asyncId) {
    process._rawDebug(`after(${asyncId})`)
    asyncIds.delete(asyncId)
  },
  destroy (asyncId) {
    process._rawDebug(`destroy(${asyncId})`)
  }
})

asyncHook.enable()

async function printLeakedEvents (f) {
  process._rawDebug('-- printLeakedEvents start')

  const before = new Set(asyncIds.values())

  const value = await f()
  process._rawDebug('-- value:', value)

  const diff = difference(asyncIds, before)

  process._rawDebug('-- before:', before)
  process._rawDebug('-- after:', asyncIds)
  process._rawDebug('-- diff:', diff)
  process._rawDebug('-- printLeakedEvents end')
}

function difference (setA, setB) {
  var _difference = new Set(setA)
  for (var elem of setB) {
    _difference.delete(elem)
  }
  return _difference
}

async function main () {
  await printLeakedEvents(async () => 0)
  await printLeakedEvents(async () => 1)
  await printLeakedEvents(async () => new Promise(function (resolve) { resolve(2) }))
  await printLeakedEvents(async () => {
    new Promise(function (resolve, reject) {
      process._rawDebug('-- resolving...')
      resolve()
    })
  })
}

main()