AMQP + NodeJS 等待通道

Question

我在 FeathersJS 中有一个服务，它启动到 RabbitMQ 的连接，问题是如何在接收请求之前等待通道准备好：

class Service {
  constructor({ amqpConnection, queueName }) {
    this.amqpConnection = amqpConnection;
    this.queueName = queueName;
    this.replyQueueName = queueName + "Reply"
  }

  async create(data, params) {
    new Promise(resolve => {
      if (!this.channel) await this.createChannel();
      channel.responseEmitter.once(correlationId, resolve);
      channel.sendToQueue(this.queueName, Buffer.from(data), {
        correlationId: asyncLocalStorage.getStore(),
        replyTo: this.replyQueueName,
      });
    });
  }

  async createChannel() {
    let connection = this.amqpConnection();
    let channel = await connection.createChannel();

    await channel.assertQueue(this.queueName, {
      durable: false,
    });

    this.channel = channel;
    channel.responseEmitter = new EventEmitter();
    channel.responseEmitter.setMaxListeners(0);
    channel.consume(
      this.replyQueueName,
      (msg) => {
        channel.responseEmitter.emit(
          msg.properties.correlationId,
          msg.content.toString("utf8")
        );
      },
      { noAck: true }
    );
  }
  ....
}

在请求期间等待创建通道似乎是一种浪费。这应该如何“正确”完成？

Answer 1

Feathers 服务可以实现一个setup method，它会在服务器启动时调用（或者你自己调用app.setup()）：

class Service {
  async setup () {
    await this.createChannel();
  }
}