From a32815cfdff3432c8f890ed5e2099885379e88a6 Mon Sep 17 00:00:00 2001
From: sta <sta.blockhead@gmail.com>
Date: Tue, 6 Jun 2017 15:27:14 +0900
Subject: [PATCH] [Modify] Replace it

---
 websocket-sharp/Server/HttpServer.cs | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/websocket-sharp/Server/HttpServer.cs b/websocket-sharp/Server/HttpServer.cs
index 6b424367..31bf64f1 100644
--- a/websocket-sharp/Server/HttpServer.cs
+++ b/websocket-sharp/Server/HttpServer.cs
@@ -594,13 +594,20 @@ namespace WebSocketSharp.Server
       }
 
       set {
-        var msg = _state.CheckIfAvailable (true, false, false);
-        if (msg != null) {
-          _log.Error (msg);
+        string msg;
+        if (!canSet (out msg)) {
+          _log.Warn (msg);
           return;
         }
 
-        _listener.UserCredentialsFinder = value;
+        lock (_sync) {
+          if (!canSet (out msg)) {
+            _log.Warn (msg);
+            return;
+          }
+
+          _listener.UserCredentialsFinder = value;
+        }
       }
     }