Move ECONNRESET value check to server initialization.

src/Microsoft.AspNetCore.Server.Kestrel/Http/Connection.cs

@@ -40,8 +40,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
         private ConnectionState _connectionState;
         private TaskCompletionSource<object> _socketClosedTcs;
 
-        bool _eConnResetChecked = false;
-
         public Connection(ListenerContext context, UvStreamHandle socket) : base(context)
         {
             _socket = socket;
@@ -202,7 +200,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
                 if (_socketClosedTcs != null)
                 {
                     // This is always waited on synchronously, so it's safe to
-                    // call on the libuv thread. 
+                    // call on the libuv thread.
                     _socketClosedTcs.TrySetResult(null);
                 }
             }
@@ -274,12 +272,6 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Http
                 return;
             }
 
-            if (!_eConnResetChecked && !Constants.ECONNRESET.HasValue)
-            {
-                Log.LogWarning("Unable to determine ECONNRESET value on this platform.");
-                _eConnResetChecked = true;
-            }
-
             var normalRead = status > 0;
             var normalDone = status == Constants.ECONNRESET || status == Constants.EOF;
             var errorDone = !(normalDone || normalRead);

src/Microsoft.AspNetCore.Server.Kestrel/Infrastructure/Constants.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System;
 using Microsoft.Extensions.PlatformAbstractions;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Infrastructure

src/Microsoft.AspNetCore.Server.Kestrel/KestrelServer.cs

@@ -94,6 +94,11 @@ namespace Microsoft.AspNetCore.Server.Kestrel
                         "ThreadCount must be positive.");
                 }
 
+                if (!Constants.ECONNRESET.HasValue)
+                {
+                    _logger.LogWarning("Unable to determine ECONNRESET value on this platform.");
+                }
+
                 engine.Start(threadCount);
                 var atLeastOneListener = false;