RebitMQ二：Work Queues

RabitMQ二：Work Queues

概述

本文示例重点为：
- RabbitMQ的的消息及队列持久化（生产者服务挂了之后保证数据不丢失）
- RabbitMQ的消息应答（消费时服务挂了之后保证消息数据不丢失）

示例

NewTask

说明：
- QueueDeclare的参数durable表示设置队列是否持久化
- IBasicProperties.Persistent设置消息是否持久化（设置消息持久化需先设置队列为可持久化，不然服务重启后，队列丢失，消息持久化也就没作用了。）

class NewTask
{
    static void Main(string[] args)
    {
        var factory = new ConnectionFactory() { HostName = "127.0.0.1" };
        using (var connection = factory.CreateConnection())
        {
            using (var channel = connection.CreateModel())
            {
                channel.QueueDeclare(queue: "task_queue", durable: true, exclusive: false, autoDelete: false, arguments: null);
                var message = GetMessage(args);
                var body = Encoding.UTF8.GetBytes(message);

                var properties = channel.CreateBasicProperties();
                properties.Persistent = true;
                channel.BasicPublish(exchange: "", routingKey: "task_queue", basicProperties: properties, body: body);
                Console.WriteLine($"Sent: {message}");
            }
        }
        Console.WriteLine("Press [enter] to exit.");
        Console.ReadLine();
    }

    private static string GetMessage(string[] args)
    {
        return ((args.Length > 0) ? string.Join(" ", args) : "Hello World!");
    }
}

Worker

说明：

• 使用BasicQos方法和prefetchCount = 1设置告诉RabbitMQ不要一次向一个worker发生一条消息，即：在处理并确认前一个消息之前，不要向工作人员发送新消息。相反，它会将它发送给下一个仍然不忙的工人。
• 消息应答：当自动应答-autoAck(automatic acknowledgement mode)等于true的时候，表示当消费者一收到消息就表示消费者收到了消息，消费者收到了消息就会立即从队列中删除。为了保证数据不丢失，设置autoAck = false,

class Worker
{
    static void Main(string[] args)
    {
        var factory = new ConnectionFactory() { HostName = "127.0.0.1" };
        using (var connection = factory.CreateConnection())
        using (var channel = connection.CreateModel())
        {
            channel.QueueDeclare(queue: "task_queue", durable: true, exclusive: false, autoDelete: false, arguments: null);
            channel.BasicQos(prefetchSize: 0, prefetchCount: 1, global: false);
            Console.WriteLine($" [*] Waiting for message.");
            var consumer = new EventingBasicConsumer(channel);
            consumer.Received += (model, ea) =>
            {
                var body = ea.Body;
                var message = Encoding.UTF8.GetString(body);
                Console.WriteLine($" [x] Received {message}");

                int dots = message.Split('.').Length - 1;
                Thread.Sleep(dots * 10000);

                Console.WriteLine(" [x] Done.");
                channel.BasicAck(deliveryTag: ea.DeliveryTag, multiple: false);
            };
            channel.BasicConsume(queue: "task_queue", autoAck: false, consumer: consumer);
            Console.WriteLine("Press [enter] to exit.");
            Console.ReadLine();
        }
    }
}

附：

Work Queues

Github