[ISSUE apache#996] invoke user callback and return error info when as…

…ync process send resp error

internal/client.go

@@ -702,8 +702,7 @@ func (c *rmqClient) ProcessSendResponse(brokerName string, cmd *remote.RemotingC
 	case ResSuccess:
 		status = primitive.SendOK
 	default:
-		status = primitive.SendUnknownError
-		return errors.New(cmd.Remark)
+		return errors.New(fmt.Sprintf("CODE: %d, DESC: %s", cmd.Code, cmd.Remark))
 	}
 
 	msgIDs := make([]string, 0)

producer/producer.go

@@ -373,13 +373,18 @@ func (p *defaultProducer) sendAsync(ctx context.Context, msg *primitive.Message,
 	ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
 	err := p.client.InvokeAsync(ctx, addr, p.buildSendRequest(mq, msg), func(command *remote.RemotingCommand, err error) {
 		cancel()
+		if err != nil {
+			h(ctx, nil, err)
+		}
+
 		resp := primitive.NewSendResult()
+		err = p.client.ProcessSendResponse(mq.BrokerName, command, resp, msg)
 		if err != nil {
 			h(ctx, nil, err)
-		} else {
-			p.client.ProcessSendResponse(mq.BrokerName, command, resp, msg)
-			h(ctx, resp, nil)
+			return
 		}
+
+		h(ctx, resp, nil)
 	})
 
 	if err != nil {