一、前言

需求：电商秒杀场景中，如果用户下单10分钟未支付，需要进行库存归还

本篇是用PHP+Laravel+RabbitMQ来实现异步延迟消息队列

二、场景

在电商项目中，当我们下单之后，一般需要 20 分钟之内或者 30 分钟之内付款，否则订单就会进入异常处理逻辑中，被取消，那么进入到异常处理逻辑中，就可以当成是一个延迟队列

公司的会议预定系统，在会议预定成功后，会在会议开始前半小时通知所有预定该会议的用户

安全工单超过 24 小时未处理，则自动拉企业微信群提醒相关责任人

用户下单外卖以后，距离超时时间还有 10 分钟时提醒外卖小哥即将超时

…

很多场景下我们都需要延迟队列。

本文以 RabbitMQ 为例来和大家聊一聊延迟队列的玩法。

使用 RabbitMQ 的 rabbitmq_delayed_message_exchange 插件来实现定时任务，这种方案较简单。

三、安装RabbitMQ延迟队列插件

官网插件下载地址

我这里直接下载了最新版本，你们根据自己的rabbitmq版本号进行下载

把下载好的文件移动到rabbitmq的插件plugins下，以我自己的Mac为例子，放到了如下路径

然后执行安装插件指令，如下

rabbitmq-plugins enable rabbitmq_delayed_message_exchange

最后重启rabbitmq服务，并刷新查看exchanges交换机有没有该插件

如上图则延迟消息队列插件安装完成

四、在Laravel框架中进行使用

新建rabbitmq服务类，包含延迟消息队列生产消息，和消费消息，如下

代码如下：

<?php

namespace App\Http\Controllers\Service;

use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;
use PhpAmqpLib\Wire\AMQPTable;

class RabbitmqServer
{
    private $host = "127.0.0.1";
    private $port = 5672;
    private $user = "guest";
    private $password = "guest";

    private $msg;
    private $channel;
    private $connection;

    //  过期时间
    const TIMEOUT_5_S = 5;     // 5s
    const TIMEOUT_10_S = 10;    // 10s

    private $exchange_logs = "logs";
    private $exchange_direct = "direct";
    private $exchange_delayed = "delayed";

    private $queue_delayed = "delayedQueue";

    const EXCHANGETYPE_FANOUT = "fanout";
    const EXCHANGETYPE_DIRECT = "direct";
    const EXCHANGETYPE_DELAYED = "x-delayed-message";

    public function __construct($type = false)
{
        $this->connection = new AMQPStreamConnection($this->host, $this->port, $this->user, $this->password);
        $this->channel = $this->connection->channel();
        // 声明Exchange
        $this->channel->exchange_declare($this->exchange_delayed, self::EXCHANGETYPE_DELAYED, false, true, false, false, false, new AMQPTable(["x-delayed-type" => self::EXCHANGETYPE_DIRECT]));
        $this->channel->queue_declare($this->queue_delayed, false, true, false, false);
        $this->channel->queue_bind($this->queue_delayed, $this->exchange_delayed, $this->queue_delayed);
    }

    /**
     * delay creat message
     */
    public function createMessageDelay($msg, $time)
{
        $delayConfig = [
            'delivery_mode' => AMQPMessage::DELIVERY_MODE_PERSISTENT,
            'application_headers' => new AMQPTable(['x-delay' => $time * 1000])
        ];
        $msg = new AMQPMessage($msg, $delayConfig);
        return $msg;
    }

    /**
     * delay send message
     */
    public function sendDelay($msg, $time = self::TIMEOUT_10_S)
{
        $msg = $this->createMessageDelay($msg, $time);;
        $this->channel->basic_publish($msg, $this->exchange_delayed, $this->queue_delayed);
        $this->channel->close();
        $this->connection->close();
    }

    /**
     * delay consum
     */
    public function consumDelay()
{
        $callback = function ($msg) {
            echo ' [x] ', $msg->body, "\n";
            $this->channel->basic_ack($msg->delivery_info['delivery_tag'], false);
        };
        $this->channel->basic_qos(null, 1, null);
        $this->channel->basic_consume($this->queue_delayed, '', false, false, false, false, $callback);
        echo ' [*] Waiting for logs. To exit press CTRL+C', "\n";
        while (count($this->channel->callbacks)) {
            $this->channel->wait();
        }

        $this->channel->close();
        $this->connection->close();
    }
}

比如新建QueueController控制器，进行测试生产消息放到延迟消息队列中

代码如下：

<?php

namespace App\Http\Controllers\Api\v1;

use App\Http\Controllers\Controller;
use App\Http\Controllers\Service\RabbitmqServer;
use App\Jobs\Queue;
use Illuminate\Http\Request;

class QueueController extends Controller
{
    //
    public function index(Request $request)
{
        //比如说现在是下订单操作
        //需求：如果用户10分钟之内不支付订单就要取消订单，并且库存归还
        $msg = $request->post();
        $Rabbit = new RabbitmqServer("x-delayed-message");
        //第一个参数发送的消息，第二个参数延迟多少秒
        $Rabbit->sendDelay(json_encode($msg),5);
    }
}

至此通过接口调试工具进行模拟生产消息即可

消息生产完毕要进行消费，这里使用的是Laravel的任务调度，代码如下

<?php

namespace App\Console\Commands;

use App\Http\Controllers\Service\RabbitmqServer;
use Illuminate\Console\Command;
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;

class RabbitmqConsumerCommand extends Command
{
    /**
     * The name and signature of the console command.
     *
     * @var string
     */
    protected $signature = 'rabbitmq_consumer';//给消费者起个command名称

    /**
     * The console command description.
     *
     * @var string
     */
    protected $description = 'Command description';

    /**
     * Create a new command instance.
     *
     * @return void
     */
    public function __construct()
{
        parent::__construct();
    }

    /**
     * Execute the console command.
     * @return int
     */
    public function handle()
{
        $Rabbit = new RabbitmqServer("x-delayed-message");
        $Rabbit->consumDelay();
    }
}

五、执行生产消息和消费消息

用postman模拟生产消息，效果如下：

然后消费消息，用一下命令，如果延迟5秒执行消费则成功

至此，就完成了rabbitmq异步延迟消息队列