Initialize ThreadCount as early as possible

This will allow you to inspect the property
in the Configure method.

Closes #404

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

@@ -73,34 +73,13 @@ namespace Microsoft.AspNet.Server.Kestrel
                 _disposables.Push(engine);
                 _disposables.Push(dateHeaderValueManager);
 
-                // Actual core count would be a better number 
+                var threadCount = information.ThreadCount;
-                // rather than logical cores which includes hyper-threaded cores.
-                // Divide by 2 for hyper-threading, and good defaults (still need threads to do webserving).
-                // Can be user overriden using IKestrelServerInformation.ThreadCount
-                var threadCount = Environment.ProcessorCount >> 1;
 
-                if (threadCount < 1)
+                if (threadCount <= 0)
                 {
-                    // Ensure shifted value is at least one
+                    throw new ArgumentOutOfRangeException(nameof(threadCount),
-                    threadCount = 1;
+                        threadCount,
-                }
+                        "ThreadCount must be positive.");
-                else if (threadCount > 16)
-                {
-                    // Receive Side Scaling RSS Processor count currently maxes out at 16
-                    // would be better to check the NIC's current hardware queues; but xplat...
-                    threadCount = 16;
-                }
-
-                if (information.ThreadCount < 0)
-                {
-                    throw new ArgumentOutOfRangeException(nameof(information.ThreadCount),
-                        information.ThreadCount,
-                        "ThreadCount cannot be negative");
-                }
-                else if (information.ThreadCount > 0)
-                {
-                    // ThreadCount has been user set, use that value
-                    threadCount = information.ThreadCount;
                 }
 
                 engine.Start(threadCount);

src/Microsoft.AspNet.Server.Kestrel/KestrelServerInformation.cs

@@ -11,21 +11,33 @@ namespace Microsoft.AspNet.Server.Kestrel
 {
     public class KestrelServerInformation : IKestrelServerInformation, IServerAddressesFeature
     {
-        public ICollection<string> Addresses { get; } = new List<string>();
+        public KestrelServerInformation(IConfiguration configuration, int threadCount)
+        {
+            Addresses = GetAddresses(configuration);
+            ThreadCount = threadCount;
+            NoDelay = true;
+        }
+
+        public ICollection<string> Addresses { get; }
 
         public int ThreadCount { get; set; }
 
-        public bool NoDelay { get; set; } = true;
+        public bool NoDelay { get; set; }
 
         public IConnectionFilter ConnectionFilter { get; set; }
 
-        public void Initialize(IConfiguration configuration)
+        private static ICollection<string> GetAddresses(IConfiguration configuration)
         {
-            var urls = configuration["server.urls"] ?? string.Empty;
+            var addresses = new List<string>();
-            foreach (var url in urls.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries))
+
+            var urls = configuration["server.urls"];
+
+            if (!string.IsNullOrEmpty(urls))
             {
-                Addresses.Add(url);
+                addresses.AddRange(urls.Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries));
             }
+
+            return addresses;
         }
     }
 }

src/Microsoft.AspNet.Server.Kestrel/ServerFactory.cs

@@ -1,6 +1,7 @@
 // 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.AspNet.Hosting;
 using Microsoft.AspNet.Hosting.Server;
 using Microsoft.AspNet.Http.Features;
@@ -26,12 +27,36 @@ namespace Microsoft.AspNet.Server.Kestrel
 
         public IServer CreateServer(IConfiguration configuration)
         {
-            var information = new KestrelServerInformation();
+            var threadCount = GetThreadCount();
-            information.Initialize(configuration);
+            var information = new KestrelServerInformation(configuration, threadCount);
             var serverFeatures = new FeatureCollection();
             serverFeatures.Set<IKestrelServerInformation>(information);
             serverFeatures.Set<IServerAddressesFeature>(information);
             return new KestrelServer(serverFeatures, _appLifetime, _loggerFactory.CreateLogger("Microsoft.AspNet.Server.Kestrel"));
         }
+
+        private static int GetThreadCount()
+        {
+            // Actual core count would be a better number
+            // rather than logical cores which includes hyper-threaded cores.
+            // Divide by 2 for hyper-threading, and good defaults (still need threads to do webserving).
+            // Can be user overriden using IKestrelServerInformation.ThreadCount
+            var threadCount = Environment.ProcessorCount >> 1;
+
+            if (threadCount < 1)
+            {
+                // Ensure shifted value is at least one
+                return 1;
+            }
+
+            if (threadCount > 16)
+            {
+                // Receive Side Scaling RSS Processor count currently maxes out at 16
+                // would be better to check the NIC's current hardware queues; but xplat...
+                return 16;
+            }
+
+            return threadCount;
+        }
     }
 }