javascript - 如何使用lib amqp.node中的consume方法获取所有消息？

Question

大家好。
你能帮助我解决 node.js 中的异步问题吗？

问题:

我正在使用amqplib module与 RabbitMQ 一起工作这里有方法 consume，它从 RabbitMQ 提供消息，但是该方法首先返回有关他启动的 promise ，在这个 promise 启动后，他调用回调来获取数据 来自 RabbitMQ，我不知道如何捕获所有消息何时发送到我的 Node js 应用程序。

更多解释，这里是我的代码，在评论的末尾代码我写了我想要的内容:

/**
 * Here my test code
 *
 * requirng amqp.node lib
 */
let amqp = require('amqplib')
  , configConnection = { /* ..config options */ }
  , queue = 'users'
  , exchange = 'users.exchange'
  , type = 'fanout'

/**
 * declare annonymous function as async and immediately called it
 */
(async () => {
  /**
   * declare connection and channel with using async/await construction
   * who support version node.js >= 8.5.0
   */
  let conn = await amqp.connect(configConnection)
  let channel = await conn.createChannel()
  await channel.assertExchange(exchange, type)
  let response = await channel.assertQueue(queue)
  /**
   * response: { queue: 'users', messageCount: 10, consumerCount: 0 }
   */
  response = await channel.bindQueue(response.queue, exchange, '')
  response = await channel.consume(response.queue, logMessage, {noAck: false})
  /**
   * {noAck: false} false for not expect an acknowledgement
   */
  console.log('reading for query finish')

  function logMessage(msg) {
    console.log("[*] recieved: '%s'", msg.content.toString())
  }
})()
  /**
   * output will show:
   * reading for query finish
   * [*] recieved: 'message content'
   * [*] recieved: 'message content'
   * [*] recieved: 'message content'
   * ...
   *
   * But i'm need show message 'reading for query finish' after when
   * all consumes will executed
   *
   * Ask: How i can do this?
   */

Answer 1

我找到了问题的答案 here .

使用中的答案:EventEmitter && Promise

魔法(对我来说)就在这里:
await new Promise(resolve => eventEmitter.once('consumeDone', resolve))

所以结束的代码是:

/**
 * Here my test code
 *
 * requirng amqp.node lib
 */
let amqp = require('amqplib')
  , EventEmitter = require('events')
  , eventEmitter = new EventEmitter()
  , timeout = 10000
  , configConnection = { /* ..config options */ }
  , queue = 'users'
  , exchange = 'users.exchange'
  , type = 'fanout'

/**
 * declare annonymous function as async and immediately called it
 */
(async () => {
  /**
   * declare connection and channel with using async/await construction
   * who support version node.js >= 8.5.0
   */
  let conn = await amqp.connect(configConnection)
  let channel = await conn.createChannel()
  await channel.assertExchange(exchange, type)
  let response = await channel.assertQueue(queue)
  /**
   * response: { queue: 'users', messageCount: 10, consumerCount: 0 }
   */
  let messageCount = response.messageCount
  response = await channel.bindQueue(response.queue, exchange, '')
  response = await channel.consume(response.queue, logMessage(messageCount), {noAck: false})
  /**
   * {noAck: false} false for not expect an acknowledgement
   */

  /**
   * declare timeout if we have problems with emit event in consume
   * we waiting when event will be emit once 'consumeDone' and promise gain resolve
   * so we can go to the next step
   */
  setTimeout(() => eventEmitter.emit('consumeDone'), timeout)
  await new Promise(resolve => eventEmitter.once('consumeDone', resolve))
  console.log('reading for query finish')

  function logMessage(messageCount) {
    return msg => {
      console.log("[*] recieved: '%s'", msg.content.toString())
      if (messageCount == msg.fields.deliveryTag) {
        eventEmitter.emit('consumeDone')
      }
    }

  }
})()