C#佇列學習筆記：RabbitMQ延遲佇列-有解無憂

一、引言

日常生活中，很多的APP都有延遲佇列的影子，比如在手機淘寶上，經常遇到APP派發的限時消費紅包，一般有幾個小時或24小時不等，假如在紅包倒計時的程序中，沒有消費掉紅包的話，紅包會自動失效，假如上述行為使用RabbitMQ延時佇列來理解的話，就是在你收到限時消費紅包的時候，手機淘寶會自動發一條延時訊息到佇列中以供消費，在規定時間內，則可正常消費，否則依TTL自動失效，

在RabbitMQ中，有兩種方式來實作延時佇列：一種是基于佇列方式，另外一種是基于訊息方式，

二、示例

2.1、發送端(生產端)

新建一個控制臺專案Send，并添加一個類RabbitMQConfig，

    class RabbitMQConfig
    {
        public static string Host { get; set; }

        public static string VirtualHost { get; set; }

        public static string UserName { get; set; }

        public static string Password { get; set; }

        public static int Port { get; set; }

        static RabbitMQConfig()
        {
            Host = "192.168.2.242";
            VirtualHost = "/";
            UserName = "hello";
            Password = "world";
            Port = 5672;
        }
    }

RabbitMQConfig.cs

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("C# RabbitMQ實作延遲佇列有以下兩種方式：");
            Console.WriteLine("1、基于佇列方式實作延遲佇列，請按1開始生產，");
            Console.WriteLine("2、基于訊息方式實作延遲佇列，請按2開始生產，");

            string chooseChar = Console.ReadLine();
            if (chooseChar == "1")
            {
                DelayMessagePublishByQueueExpires();
            }
            else if (chooseChar == "2")
            {
                DelayMessagePublishByMessageTTL();
            }
            Console.ReadLine();
        }

        /// <summary>
        /// 基于佇列方式實作延遲佇列
        /// 將佇列中所有訊息的TTL(Time To Live，即過期時間)設定為一樣
        /// </summary>
        private static void DelayMessagePublishByQueueExpires()
        {
            const string MessagePrefix = "message_";
            const int PublishMessageCount = 6;
            const int QuequeExpirySeconds = 1000 * 30;
            const int MessageExpirySeconds = 1000 * 10;

            var factory = new ConnectionFactory()
            {
                HostName = RabbitMQConfig.Host,
                Port = RabbitMQConfig.Port,
                VirtualHost = RabbitMQConfig.VirtualHost,
                UserName = RabbitMQConfig.UserName,
                Password = RabbitMQConfig.Password,
                Protocol = Protocols.DefaultProtocol
            };

            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    //當同時指定了queue和message的TTL值，則兩者中較小的那個才會起作用，
                    Dictionary<string, object> dict = new Dictionary<string, object>
                    {
                        { "x-expires", QuequeExpirySeconds },//佇列過期時間
                        { "x-message-ttl", MessageExpirySeconds },//訊息過期時間
                        { "x-dead-letter-exchange", "dead exchange 1" },//過期訊息轉向路由
                        { "x-dead-letter-routing-key", "dead routing key 1" }//過期訊息轉向路由的routing key
                    };

                    //宣告佇列
                    channel.QueueDeclare(queue: "delay1", durable: true, exclusive: false, autoDelete: false, arguments: dict);


                    //向該訊息佇列發送訊息message
                    for (int i = 0; i < PublishMessageCount; i++)
                    {
                        var message = MessagePrefix + i.ToString();
                        var body = Encoding.UTF8.GetBytes(message);
                        channel.BasicPublish(exchange: "", routingKey: "delay1", basicProperties: null, body: body);
                        Thread.Sleep(1000 * 2);
                        Console.WriteLine($"{DateTime.Now.ToString()} Send {message} MessageExpirySeconds {MessageExpirySeconds / 1000}");
                    }
                }
            }
        }

        /// <summary>
        /// 基于訊息方式實作延遲佇列
        /// 對佇列中訊息進行單獨設定，每條訊息的TTL可以不同，
        /// </summary>
        private static void DelayMessagePublishByMessageTTL()
        {
            const string MessagePrefix = "message_";
            const int PublishMessageCount = 6;
            int MessageExpirySeconds = 0;

            var factory = new ConnectionFactory()
            {
                HostName = RabbitMQConfig.Host,
                Port = RabbitMQConfig.Port,
                VirtualHost = RabbitMQConfig.VirtualHost,
                UserName = RabbitMQConfig.UserName,
                Password = RabbitMQConfig.Password,
                Protocol = Protocols.DefaultProtocol
            };

            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    Dictionary<string, object> dict = new Dictionary<string, object>
                    {
                        { "x-dead-letter-exchange", "dead exchange 2" },//過期訊息轉向路由
                        { "x-dead-letter-routing-key", "dead routing key 2" }//過期訊息轉向路由的routing key
                    };

                    //宣告佇列
                    channel.QueueDeclare(queue: "delay2", durable: true, exclusive: false, autoDelete: false, arguments: dict);

                    //向該訊息佇列發送訊息message
                    Random random = new Random();
                    for (int i = 0; i < PublishMessageCount; i++)
                    {
                        MessageExpirySeconds = i * 1000;
                        var properties = channel.CreateBasicProperties();
                        properties.Expiration = MessageExpirySeconds.ToString();
                        var message = MessagePrefix + i.ToString();
                        var body = Encoding.UTF8.GetBytes(message);
                        channel.BasicPublish(exchange: "", routingKey: "delay2", basicProperties: properties, body: body);
                        Console.WriteLine($"{DateTime.Now.ToString()} Send {message} MessageExpirySeconds {MessageExpirySeconds / 1000}");
                    }
                }
            }
        }
    }

Program.cs

2.2、接收端(消費端)

新建一個控制臺專案Receive，按住Alt鍵，將發送端RabbitMQConfig類拖一個快捷方式到Receive專案中，

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("C# RabbitMQ實作延遲佇列有以下兩種方式：");
            Console.WriteLine("1、基于佇列方式實作延遲佇列，請按1開始消費，");
            Console.WriteLine("2、基于訊息方式實作延遲佇列，請按2開始消費，");

            string chooseChar = Console.ReadLine();
            if (chooseChar == "1")
            {
                DelayMessageConsumeByQueueExpires();
            }
            else if (chooseChar == "2")
            {
                DelayMessageConsumeByMessageTTL();
            }
            Console.ReadLine();
        }

        public static void DelayMessageConsumeByQueueExpires()
        {
            var factory = new ConnectionFactory()
            {
                HostName = RabbitMQConfig.Host,
                Port = RabbitMQConfig.Port,
                VirtualHost = RabbitMQConfig.VirtualHost,
                UserName = RabbitMQConfig.UserName,
                Password = RabbitMQConfig.Password,
                Protocol = Protocols.DefaultProtocol
            };

            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare(exchange: "dead exchange 1", type: "direct");
                    string name = channel.QueueDeclare().QueueName;
                    channel.QueueBind(queue: name, exchange: "dead exchange 1", routingKey: "dead routing key 1");

                    var consumer = new EventingBasicConsumer(channel);
                    consumer.Received += (model, ea) =>
                    {
                        var message = Encoding.UTF8.GetString(ea.Body);
                        Console.WriteLine($"{DateTime.Now.ToString()} Received {message}");
                    };
                    channel.BasicConsume(queue: name, noAck: true, consumer: consumer);
                    Console.ReadKey();
                }
            }
        }

        public static void DelayMessageConsumeByMessageTTL()
        {
            var factory = new ConnectionFactory()
            {
                HostName = RabbitMQConfig.Host,
                Port = RabbitMQConfig.Port,
                VirtualHost = RabbitMQConfig.VirtualHost,
                UserName = RabbitMQConfig.UserName,
                Password = RabbitMQConfig.Password,
                Protocol = Protocols.DefaultProtocol
            };

            using (var connection = factory.CreateConnection())
            {
                using (var channel = connection.CreateModel())
                {
                    channel.ExchangeDeclare(exchange: "dead exchange 2", type: "direct");
                    string name = channel.QueueDeclare().QueueName;
                    channel.QueueBind(queue: name, exchange: "dead exchange 2", routingKey: "dead routing key 2");

                    var consumer = new EventingBasicConsumer(channel);
                    consumer.Received += (model, ea) =>
                    {
                        var message = Encoding.UTF8.GetString(ea.Body);
                        Console.WriteLine($"{DateTime.Now.ToString()} Received {message}");
                    };
                    channel.BasicConsume(queue: name, noAck: true, consumer: consumer);
                    Console.ReadKey();
                }
            }
        }
    }

Program.cs

2.3、運行結果

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標籤：C#

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