目錄

• 前言
• 實(shí)現(xiàn)延時(shí)隊(duì)列的兩種方式
• 利用rabbitmq死信隊(duì)列x-dead-letter-exchange和x-dead-letter-routing-key
• .NETCore實(shí)現(xiàn)方式
• rabbitmq通過(guò)安裝插件的形式實(shí)現(xiàn)(推薦)
• .NET Core 實(shí)現(xiàn)
• 第一種方式的缺陷以及解決方案

前言

此文章用來(lái)記錄自己學(xué)習(xí)延時(shí)隊(duì)列過(guò)程的文章，并用.NET這兩種方式實(shí)現(xiàn)了簡(jiǎn)單的Demo。

延時(shí)隊(duì)列的應(yīng)用場(chǎng)景 應(yīng)用下單后，30分鐘沒(méi)有支付的話(huà)，則自動(dòng)取消訂單活動(dòng)開(kāi)始前30分鐘，提醒參賽者參加活動(dòng)。活動(dòng)結(jié)束后，30分鐘后提醒未進(jìn)行評(píng)價(jià)的參賽人員進(jìn)行評(píng)價(jià)…

上述的場(chǎng)景都可以使用延時(shí)隊(duì)列進(jìn)行對(duì)應(yīng)的處理。

上面的場(chǎng)景雖說(shuō)可以通過(guò)定時(shí)器也可以處理，但有點(diǎn)浪費(fèi)資源， 而上述的場(chǎng)景時(shí)間是不定的，例如有兩個(gè)活動(dòng)需要提醒參賽者參加，一個(gè)是7點(diǎn)開(kāi)始 ，另一個(gè)是8點(diǎn)開(kāi)始，那么觸發(fā)處理的一個(gè)是6點(diǎn)半，一個(gè)是7點(diǎn)半。

實(shí)現(xiàn)延時(shí)隊(duì)列的兩種方式

使用Rabbitmq實(shí)現(xiàn)延時(shí)隊(duì)列可以讓消息持久化，也支持分布式

缺點(diǎn)第一種第一種方式的缺陷以及解決方案第二種這個(gè)插件的當(dāng)前設(shè)計(jì)并不真正適合具有大量延遲消息（例如成百上千或數(shù)百萬(wàn)）的場(chǎng)景。詳情信息

利用rabbitmq死信隊(duì)列x-dead-letter-exchange和x-dead-letter-routing-key

實(shí)現(xiàn)需要?jiǎng)?chuàng)建兩對(duì)交換機(jī)和隊(duì)列，其中需要對(duì)其中一對(duì)的隊(duì)列進(jìn)行設(shè)置x-dead-letter-exchange和x-dead-letter-routing-key屬性，屬性指定轉(zhuǎn)發(fā)到另一對(duì)的交換機(jī)，

隨后實(shí)現(xiàn)流程圖如下：

.NETCore實(shí)現(xiàn)方式

項(xiàng)目：.NET Core 控制臺(tái)項(xiàng)目

install-package RabbitMQ.Client

生產(chǎn)者代碼：

    ConnectionFactory connectionFactory = new ConnectionFactory    {UserName = "guest",Password = "guest",HostName = "127.0.0.1"    };    //創(chuàng)建連接    var connection = connectionFactory.CreateConnection();    //創(chuàng)建通道    var channl = connection.CreateModel();   //指定隊(duì)列的x-dead-letter-exchange和x-dead-letter-routing-key    Dictionary<string, object> queueArgs = new Dictionary<string, object>()    {{ "x-dead-letter-exchange","exchange.business.test" },{"x-dead-letter-routing-key","businessRoutingkey" }    };    //延時(shí)的交換機(jī)和隊(duì)列綁定    channl.ExchangeDeclare("exchange.business.dlx", "direct", true, false, null);    channl.QueueDeclare("queue.business.dlx", true, false, false, queueArgs);    channl.QueueBind("queue.business.dlx", "exchange.business.dlx", "");    //業(yè)務(wù)的交換機(jī)和隊(duì)列綁定    channl.ExchangeDeclare("exchange.business.test", "direct", true, false, null);    channl.QueueDeclare("queue.business.test", true, false, false, null);    channl.QueueBind("queue.business.test", "exchange.business.test", "businessRoutingkey", null);    Console.WriteLine("生產(chǎn)者開(kāi)始發(fā)送消息");    while (true)    {string message = Console.ReadLine();var body = Encoding.UTF8.GetBytes(message);var properties = channl.CreateBasicProperties();properties.Persistent = true;properties.Expiration = "5000";//發(fā)送一條延時(shí)5秒的消息channl.BasicPublish("exchange.business.dlx", "", properties, body);    }

消費(fèi)者

    ConnectionFactory connectionFactory = new ConnectionFactory    {UserName = "guest",Password = "guest",HostName = "127.0.0.1"    };    //創(chuàng)建連接    var connection = connectionFactory.CreateConnection();    var channel = connection.CreateModel();    EventingBasicConsumer consumer = new EventingBasicConsumer(channel);    //給消費(fèi)時(shí)添加一個(gè)委托    consumer.Received += (obj, ea) =>    {var message = Encoding.UTF8.GetString(ea.Body.ToArray());//打印消費(fèi)的消息Console.WriteLine(message);channel.BasicAck(ea.DeliveryTag, false);    };    //消費(fèi)queue.business.test隊(duì)列的消息    channel.BasicConsume("queue.business.test", false, consumer);    Console.ReadKey();    channel.Dispose();    connection.Close();

實(shí)現(xiàn)效果：

rabbitmq通過(guò)安裝插件的形式實(shí)現(xiàn)(推薦)

使用rabbitmq_delayed_message_exchange 插件提供的x-delayed-message類(lèi)型的交換機(jī)

下載插件的地址：https://www.rabbitmq.com/community-plugins.html
選中rabbitmq_delayed_message_exchange插件

該插件使用只需要聲明交換機(jī)的時(shí)候，指定x-delayed-message類(lèi)型，然后添加x-delayed-type參數(shù)即可

.NET Core 實(shí)現(xiàn)

生產(chǎn)者

    ConnectionFactory connectionFactory = new ConnectionFactory()    {UserName = "guest",Password = "guest",HostName = "127.0.0.1"    };    var connection = connectionFactory.CreateConnection();    var channel = connection.CreateModel();    Dictionary<string, object> exchangeArgs = new Dictionary<string, object>()    {{"x-delayed-type","direct" }    };    //指定x-delayed-message 類(lèi)型的交換機(jī)，并且添加x-delayed-type屬性    channel.ExchangeDeclare("plug.delay.exchange", "x-delayed-message", true, false, exchangeArgs);    channel.QueueDeclare("plug.delay.queue", true, false, false, null);    channel.QueueBind("plug.delay.queue", "plug.delay.exchange", "plugdelay");    var properties = channel.CreateBasicProperties();    Console.WriteLine("生產(chǎn)者開(kāi)始發(fā)送消息");    Dictionary<string, object> headers = new Dictionary<string, object>()    {{"x-delay","5000" }    };    properties.Persistent = true;    properties.Headers = headers;    while (true)    {string message = Console.ReadLine();var body = Encoding.UTF8.GetBytes(message);channel.BasicPublish("plug.delay.exchange", "plugdelay", properties, body);    }

消費(fèi)者：

    ConnectionFactory connectionFactory = new ConnectionFactory    {UserName = "guest",Password = "guest",HostName = "127.0.0.1"    };    //創(chuàng)建連接    var connection = connectionFactory.CreateConnection();    var channel = connection.CreateModel();    EventingBasicConsumer consumer = new EventingBasicConsumer(channel);    consumer.Received += (obj, ea) =>    {var message = Encoding.UTF8.GetString(ea.Body.ToArray());Console.WriteLine(message);channel.BasicAck(ea.DeliveryTag, false);    };    channel.BasicConsume("plug.delay.queue", false, consumer);    Console.ReadKey();    channel.Dispose();    connection.Close();

實(shí)現(xiàn)效果：

第一種方式的缺陷以及解決方案

如果存在A、B消息進(jìn)入了隊(duì)列中，A在前，B在后，如果B消息的過(guò)期時(shí)間比A的過(guò)期時(shí)間要早，消費(fèi)的時(shí)候，并不會(huì)先消費(fèi)B，再消費(fèi)A，而是B會(huì)等A先消費(fèi)，即使A要晚過(guò)期

舉例

生產(chǎn)者代碼修改成如下：

    ConnectionFactory connectionFactory = new ConnectionFactory    {UserName = "guest",Password = "guest",HostName = "127.0.0.1"    };    //創(chuàng)建連接    var connection = connectionFactory.CreateConnection();    //創(chuàng)建通道    var channl = connection.CreateModel();    Dictionary<string, object> queueArgs = new Dictionary<string, object>()    {{ "x-dead-letter-exchange","exchange.business.test" },{"x-dead-letter-routing-key","businessRoutingkey" }    };    //延時(shí)的交換機(jī)和隊(duì)列綁定    channl.ExchangeDeclare("exchange.business.dlx", "direct", true, false, null);    channl.QueueDeclare("queue.business.dlx", true, false, false, queueArgs);    channl.QueueBind("queue.business.dlx", "exchange.business.dlx", "");    //業(yè)務(wù)的交換機(jī)和隊(duì)列綁定    channl.ExchangeDeclare("exchange.business.test", "direct", true, false, null);    channl.QueueDeclare("queue.business.test", true, false, false, null);    channl.QueueBind("queue.business.test", "exchange.business.test", "businessRoutingkey", null);    string message1 = "Hello Word!1";    string message2 = "Hello Word!2";    var body1 = Encoding.UTF8.GetBytes(message1);    var body2 = Encoding.UTF8.GetBytes(message2);    var properties = channl.CreateBasicProperties();    properties.Persistent = true;    //先發(fā)送過(guò)期時(shí)間5秒的消息    properties.Expiration = "5000";    channl.BasicPublish("exchange.business.dlx", "", properties, body2);    //再發(fā)送過(guò)期時(shí)間3秒的消息    properties.Expiration = "3000";    channl.BasicPublish("exchange.business.dlx", "", properties, body1);

結(jié)果：

這里先發(fā)了延時(shí)20秒的A消息，然后又發(fā)了延時(shí)10秒的B消息，但是最終結(jié)果并不是先消費(fèi)了B消息，而是等A消息過(guò)期后，立刻再去消費(fèi)B。

這個(gè)會(huì)影響什么業(yè)務(wù)呢？好比兩個(gè)C、D活動(dòng)，C活動(dòng)開(kāi)始時(shí)間是7點(diǎn)，D活動(dòng)開(kāi)始時(shí)間是5點(diǎn)，那么D活動(dòng)提醒需要等到C活動(dòng)提醒后，才會(huì)立刻提醒，這明顯不符合我們的業(yè)務(wù)需求。

解決方案 每個(gè)活動(dòng)都是單獨(dú)的創(chuàng)建自己的交換機(jī)和隊(duì)列使用第二種實(shí)現(xiàn)方式，即使用插件的形式。

第一種不太現(xiàn)實(shí)，因?yàn)槿绻顒?dòng)多的話(huà)，則會(huì)創(chuàng)建很多的隊(duì)列，而且只會(huì)使用一次。

業(yè)務(wù)上還是推薦使用插件的實(shí)現(xiàn)方式。

第二種方式的效果

github地址：

https://github.com/MDZZ3/RabbitmqDelay

到此這篇關(guān)于.NETCore基于RabbitMQ實(shí)現(xiàn)延時(shí)隊(duì)列的兩方法的文章就介紹到這了,更多相關(guān).NETCore RabbitMQ 內(nèi)容請(qǐng)搜索以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持！