add MQ exceptions message to log.

src/DotNetCore.CAP.Kafka/KafkaConsumerClient.cs

@@ -12,7 +12,9 @@ namespace DotNetCore.CAP.Kafka
         private readonly KafkaOptions _kafkaOptions;
         private Consumer<Null, string> _consumerClient;
 
-        public event EventHandler<MessageContext> MessageReceieved;
+        public event EventHandler<MessageContext> OnMessageReceieved;
+
+        public event EventHandler<string> OnError;
 
         public IDeserializer<string> StringDeserializer { get; set; }
 
@@ -67,6 +69,7 @@ namespace DotNetCore.CAP.Kafka
             _consumerClient = new Consumer<Null, string>(config, null, StringDeserializer);
 
             _consumerClient.OnMessage += ConsumerClient_OnMessage;
+            _consumerClient.OnError += ConsumerClient_OnError;
         }
 
         private void ConsumerClient_OnMessage(object sender, Message<Null, string> e)
@@ -77,7 +80,12 @@ namespace DotNetCore.CAP.Kafka
                 Name = e.Topic,
                 Content = e.Value
             };
-            MessageReceieved?.Invoke(sender, message);
+            OnMessageReceieved?.Invoke(sender, message);
+        }
+
+        private void ConsumerClient_OnError(object sender, Error e)
+        {
+            OnError?.Invoke(sender, e.Reason);
         }
 
         #endregion private methods

src/DotNetCore.CAP.RabbitMQ/RabbitMQConsumerClient.cs

@@ -18,7 +18,8 @@ namespace DotNetCore.CAP.RabbitMQ
         private IModel _channel;
         private ulong _deliveryTag;
 
-        public event EventHandler<MessageContext> MessageReceieved;
+        public event EventHandler<MessageContext> OnMessageReceieved;
+        public event EventHandler<string> OnError;
 
         public RabbitMQConsumerClient(string queueName, RabbitMQOptions options)
         {
@@ -53,6 +54,7 @@ namespace DotNetCore.CAP.RabbitMQ
         {
             var consumer = new EventingBasicConsumer(_channel);
             consumer.Received += OnConsumerReceived;
+            consumer.Shutdown += OnConsumerShutdown;
             _channel.BasicConsume(_queueName, false, consumer);
             while (true)
             {
@@ -90,7 +92,12 @@ namespace DotNetCore.CAP.RabbitMQ
                 Name = e.RoutingKey,
                 Content = Encoding.UTF8.GetString(e.Body)
             };
-            MessageReceieved?.Invoke(sender, message);
+            OnMessageReceieved?.Invoke(sender, message);
+        }
+
+        private void OnConsumerShutdown(object sender, ShutdownEventArgs e)
+        {
+            OnError?.Invoke(sender, e.Cause?.ToString());
         }
     }
 }
\ No newline at end of file

src/DotNetCore.CAP/IConsumerClient.cs

 using System;
 using System.Threading;
-using DotNetCore.CAP.Infrastructure;
 
 namespace DotNetCore.CAP
 {
@@ -17,6 +16,8 @@ namespace DotNetCore.CAP
 
         void Commit();
 
-        event EventHandler<MessageContext> MessageReceieved;
+        event EventHandler<MessageContext> OnMessageReceieved;
+
+        event EventHandler<string> OnError;
     }
 }
\ No newline at end of file

src/DotNetCore.CAP/IConsumerHandler.Default.cs

@@ -95,7 +95,7 @@ namespace DotNetCore.CAP
 
         private void RegisterMessageProcessor(IConsumerClient client)
         {
-            client.MessageReceieved += (sender, message) =>
+            client.OnMessageReceieved += (sender, message) =>
             {
                 _logger.EnqueuingReceivedMessage(message.Name, message.Content);
 
@@ -106,6 +106,11 @@ namespace DotNetCore.CAP
                 }
                 Pulse();
             };
+
+            client.OnError += (sender, reason) =>
+            {
+                _logger.LogError(reason);
+            };
         }
 
         private CapReceivedMessage StoreMessage(IServiceScope serviceScope, MessageContext messageContext)