Merge DefaultHttpRequestIdentifierFeature and HttpRequestIdentifierFeature

Author: benaadams

Diff for: src/Microsoft.AspNet.Http/DefaultHttpContext.cs

@@ -123,7 +123,7 @@ private IHttpRequestIdentifierFeature RequestIdentifierFeature
                 return FeatureHelpers.GetOrCreate<IHttpRequestIdentifierFeature>(
                   this,
                   _features,
-                  () => new DefaultHttpRequestIdentifierFeature());
+                  () => new HttpRequestIdentifierFeature());
             }
             set
             {

Diff for: src/Microsoft.AspNet.Http/DefaultHttpRequestIdentifierFeature.cs

@@ -1,10 +1,64 @@
 // 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 System.Threading;
+
 namespace Microsoft.AspNet.Http.Features.Internal
 {
     public class HttpRequestIdentifierFeature : IHttpRequestIdentifierFeature
     {
-        public virtual string TraceIdentifier { get; set; }
+        // Base64 encoding - but in ascii sort order for easy text based sorting 
+        private static readonly string _encode32Chars = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
+        // Seed the _requestId for this application instance with 
+        // the number of 100-nanosecond intervals that have elapsed since 12:00:00 midnight, January 1, 0001
+        // for a roughly increasing _requestId over restarts
+        private static long _requestId = DateTime.UtcNow.Ticks;
+
+        private string _id = null;
+
+        public string TraceIdentifier
+        {
+            get
+            {
+                // Don't incur the cost of generating the request ID until it's asked for
+                if (_id == null)
+                {
+                    _id = GenerateRequestId(Interlocked.Increment(ref _requestId));
+                }
+                return _id;
+            }
+            set
+            {
+                _id = value;
+            }
+        }
+
+        private static unsafe string GenerateRequestId(long id)
+        {
+            // The following routine is ~310% faster than calling long.ToString() on x64
+            // and ~600% faster than calling long.ToString() on x86 in tight loops of 1 million+ iterations
+            // See: https://github.com/aspnet/Hosting/pull/385
+
+            // stackalloc to allocate array on stack rather than heap
+            char* charBuffer = stackalloc char[13];
+
+            charBuffer[0] = _encode32Chars[(int)(id >> 60) & 31];
+            charBuffer[1] = _encode32Chars[(int)(id >> 55) & 31];
+            charBuffer[2] = _encode32Chars[(int)(id >> 50) & 31];
+            charBuffer[3] = _encode32Chars[(int)(id >> 45) & 31];
+            charBuffer[4] = _encode32Chars[(int)(id >> 40) & 31];
+            charBuffer[5] = _encode32Chars[(int)(id >> 35) & 31];
+            charBuffer[6] = _encode32Chars[(int)(id >> 30) & 31];
+            charBuffer[7] = _encode32Chars[(int)(id >> 25) & 31];
+            charBuffer[8] = _encode32Chars[(int)(id >> 20) & 31];
+            charBuffer[9] = _encode32Chars[(int)(id >> 15) & 31];
+            charBuffer[10] = _encode32Chars[(int)(id >> 10) & 31];
+            charBuffer[11] = _encode32Chars[(int)(id >> 5) & 31];
+            charBuffer[12] = _encode32Chars[(int)id & 31];
+
+            // string ctor overload that takes char*
+            return new string(charBuffer, 0, 13);
+        }
     }
 }

Diff for: src/Microsoft.AspNet.Http/Features/HttpRequestIdentifierFeature.cs

@@ -6,8 +6,8 @@
         "url": "git://github.com/aspnet/httpabstractions"
     },
     "compilationOptions": {
-			"warningsAsErrors": true,
-			"allowUnsafe": true
+        "warningsAsErrors": true,
+        "allowUnsafe": true
     },
     "dependencies": {
         "Microsoft.AspNet.Http.Abstractions": "1.0.0-*",

Diff for: src/Microsoft.AspNet.Http/project.json

@@ -11,7 +11,7 @@ public class DeafultHttpRequestIdentifierFeatureTests
         [Fact]
         public void TraceIdentifier_ReturnsId()
         {
-            var feature = new DefaultHttpRequestIdentifierFeature();
+            var feature = new HttpRequestIdentifierFeature();
 
             var id = feature.TraceIdentifier;
 
@@ -21,7 +21,7 @@ public void TraceIdentifier_ReturnsId()
         [Fact]
         public void TraceIdentifier_ReturnsStableId()
         {
-            var feature = new DefaultHttpRequestIdentifierFeature();
+            var feature = new HttpRequestIdentifierFeature();
 
             var id1 = feature.TraceIdentifier;
             var id2 = feature.TraceIdentifier;
@@ -32,8 +32,8 @@ public void TraceIdentifier_ReturnsStableId()
         [Fact]
         public void TraceIdentifier_ReturnsUniqueIdForDifferentInstances()
         {
-            var feature1 = new DefaultHttpRequestIdentifierFeature();
-            var feature2 = new DefaultHttpRequestIdentifierFeature();
+            var feature1 = new HttpRequestIdentifierFeature();
+            var feature2 = new HttpRequestIdentifierFeature();
 
             var id1 = feature1.TraceIdentifier;
             var id2 = feature2.TraceIdentifier;