erizet / serversentevent4net Goto Github PK

表现：启用心跳，一段时间后，断开客户端。然后程序会在不存在的连接上试图发送心跳，因为缺少了异常的捕获，导致服务端崩溃，
异常如下：
System.IO.IOException ---> System.Net.HttpListenerException: 企图在不存在的网络连接上进行操作。
在 System.Net.HttpResponseStream.Write(Byte[] buffer, Int32 offset, Int32 size)
在 Microsoft.Owin.Host.HttpListener.RequestProcessing.ExceptionFilterStream.Write(Byte[] buffer, Int32 offset, Int32 count)
--- 内部异常堆栈跟踪的结尾 ---
在 Microsoft.Owin.Host.HttpListener.RequestProcessing.ExceptionFilterStream.Write(Byte[] buffer, Int32 offset, Int32 count)
在 System.Net.Http.Internal.DelegatingStream.Write(Byte[] buffer, Int32 offset, Int32 count)
在 System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
在 System.IO.StreamWriter.Flush()
在 ServerSentEvent4Net.ServerSentEvent.Client.Send(IMessage msg) 位置 D:\Code\TFS2012\QinQouShui\QouShui\QProtocol\ServerSentEvent4Net\ServerSentEvent.cs:行号 240
在 ServerSentEvent4Net.ServerSentEvent.<>c__DisplayClass24_0.b__0(Client c) 位置 D:\Code\TFS2012\QinQouShui\QouShui\QProtocol\ServerSentEvent4Net\ServerSentEvent.cs:行号 120
在 System.Collections.Generic.List1.ForEach(Action1 action)
在 ServerSentEvent4Net.ServerSentEvent.SendAndRemoveDisconneced(List`1 clientsToSendTo, Message msg) 位置 D:\Code\TFS2012\QinQouShui\QouShui\QProtocol\ServerSentEvent4Net\ServerSentEvent.cs:行号 120
在 ServerSentEvent4Net.ServerSentEvent.Send(Message msg) 位置 D:\Code\TFS2012\QinQouShui\QouShui\QProtocol\ServerSentEvent4Net\ServerSentEvent.cs:行号 108

修正方法：增加通用异常捕获，修正后的代码如下：
` public void Send(IMessage msg)
{
try
{
// Only send retry once for each connection
if (IsRetrySent)
msg.Retry = null;

                var text = msg.ToString();
                StreamWriter.WriteLine(text);
                StreamWriter.Flush();

                if (!Message.IsOnlyComment(msg))
                    LastMessageId = msg.Id;

                if (!string.IsNullOrWhiteSpace(msg.Retry))
                    IsRetrySent = true;
            }
            catch (HttpException ex)
            {
                if (ex.ErrorCode == -2147023667) // The remote host closed the connection. 
                {
                    IsConnected = false;
                }
            }
            catch (System.ServiceModel.CommunicationException)
            {
                IsConnected = false;
            }
            **catch (IOException ex)
            {
                //IO异常，可判定为已断开
                IsConnected = false;
                Console.WriteLine("SSE Send Error:" + GetErr(ex));
            }
            catch (Exception ex)
            {
                Console.WriteLine("SSE Send Error:" + GetErr(ex));
            }**
        }

        string GetErr(Exception ex)
        {
            Exception innerException = ex.InnerException;
            string err = ex.Message;
            while (innerException != null)
            {
                err = innerException.Message;
                innerException = innerException.InnerException;
            }
            return err;
        }`

When first event is sent client don't recieve it. Then events are recieved with delay. That is first sent event are recieved on second time, second event on third time.

Sometimes client may recieve two events and on the next time skip again.

I know that it is promblem in PushStreamContent and I also couldn't solve this problem before using ServerSentEvent4Net