今天和大家分享一个简单的rabbit实现延迟任务的方法，rabbit实现延迟队列有两种方式，一种是队列或者消息的TTL（Time To Live），另一种是rabbit的rabbitmq-delayed-message-exchange插件，今天我和大家分享下TTL的使用方法。

rabbit有Per-Queue Message TTL和Per-Message TTL两种设置超时的方式，分别指针对消息和队列的，给消息添加过期时间相对比较灵活，这样不用每一种过期时间都去建立一个队列去监听，给消息设置过期时间方法

$msg = new AMQPMessage('hello expiration!');
$msg->set("expiration","5000");    //关键一点：超时时间必须设置成字符串，否则不会生效！单位是ms

好了这会儿大家会想超时之后的处理在哪写呢，总有个超时的回调或者什么吧，rabbit可以给队列设置一个x-dead-letter-exchange，Dead letter routing key，意思是消息超时后的转发队列。

$channel->queue_declare("waitSendQueue",false,false,false,false,false,new AMQPTable(array
("x-dead-letter-exchange"=>"expireExchange")));     

waitSendQueue上的消息如果超时了会转发给expireExchange，那我只要去监听expireExchange上的消息，拿到消息去处理业务，就完成了我们的延迟任务，那么接下来上代码.。
客户端：

/**
 * Created by PhpStorm.
 * User: qyc
 * Date: 2017/8/14
 * Time: 下午2:18
 */

require_once dirname(__DIR__) . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;
use PhpAmqpLib\Wire\AMQPTable;
$con = new AMQPStreamConnection('localhost', 5672, "guest", "guest");

$channel = $con->channel();
//定义等待exchange
$channel->exchange_declare('waitSendExchange', 'fanout', false, false, false);
//定义过期exchange
$channel->exchange_declare('expireExchange', 'fanout', false, false, false);
//定义过期queue
$channel->queue_declare("expireQueue",false,false,false,false,false);
//定义等待queue
$channel->queue_declare("waitSendQueue",false,false,false,false,false,new AMQPTable(array
("x-dead-letter-exchange"=>"expireExchange")));
$channel->queue_bind("waitSendQueue","waitSendExchange");
$channel->queue_bind("expireQueue","expireExchange");

$msg = new AMQPMessage('hello expiration!');
/*
 * 设置超时时间
 */
$msg->set("expiration","5000");

/**
 * 向等待exchage发布消息
 */
$channel->basic_publish($msg, 'waitSendExchange');

echo 'send1:' . date('Y-m-d H:i:s') . "\n";

$channel->close();
$con->close();

服务端

/**
 * Created by PhpStorm.
 * User: qyc
 * Date: 2017/8/14
 * Time: 下午2:30
 */

require_once dirname(__DIR__) . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Wire\AMQPTable;

$con  = new AMQPStreamConnection("localhost",5672,"guest","guest");
$channel = $con->channel();

$channel = $con->channel();
//定义等待exchange
$channel->exchange_declare('waitSendExchange', 'fanout', false, false, false);
//定义过期exchange
$channel->exchange_declare('expireExchange', 'fanout', false, false, false);
//定义过期queue
$channel->queue_declare("expireQueue",false,false,false,false,false);
//定义等待queue
$channel->queue_declare("waitSendQueue",false,false,false,false,false,new AMQPTable(array
("x-dead-letter-exchange"=>"expireExchange")));
$channel->queue_bind("waitSendQueue","waitSendExchange");
$channel->queue_bind("expireQueue","expireExchange");

$callback = function ($msg){
    echo "\n".' [x] ', $msg->body, "\n";
    echo "receive2:".date("Y-m-d H:i:s")."\n";
};
/**
 * 订阅超时queue
 */
$channel->basic_consume("expireQueue","",false,true,false,false,$callback);

while (count($channel->callbacks)){
    $channel->wait();
}

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

结果：
发送：

image.png

接受：

image.png