Merge pull request #2561 from justinvp/httpmethod

Optimize HttpMethod.GetHashCode()

src/System.Net.Http/src/System/Net/Http/HttpMethod.cs

@@ -1,17 +1,14 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-using System;
-using System.Collections.Generic;
-using System.Text;
-using System.Threading.Tasks;
-using System.Diagnostics.Contracts;
+using System.Diagnostics;
 
 namespace System.Net.Http
 {
     public class HttpMethod : IEquatable<HttpMethod>
     {
-        private string _method;
+        private readonly string _method;
+        private int _hashcode;
 
         private static readonly HttpMethod s_getMethod = new HttpMethod("GET");
         private static readonly HttpMethod s_putMethod = new HttpMethod("PUT");
@@ -21,7 +18,7 @@ public class HttpMethod : IEquatable<HttpMethod>
         private static readonly HttpMethod s_optionsMethod = new HttpMethod("OPTIONS");
         private static readonly HttpMethod s_traceMethod = new HttpMethod("TRACE");
 
-        // Don't expose CONNECT as static property, since it's used by the transport to connect to a proxy. 
+        // Don't expose CONNECT as static property, since it's used by the transport to connect to a proxy.
         // CONNECT is not used by users directly.
 
         public static HttpMethod Get
@@ -106,7 +103,17 @@ public override bool Equals(object obj)
 
         public override int GetHashCode()
         {
-            return _method.ToUpperInvariant().GetHashCode();
+            if (_hashcode == 0)
+            {
+                // If _method is already uppercase, _method.GetHashCode() can be
+                // used instead of _method.ToUpperInvariant().GetHashCode(),
+                // avoiding the unnecessary extra string allocation.
+                _hashcode = IsUpperAscii(_method) ?
+                    _method.GetHashCode() :
+                    _method.ToUpperInvariant().GetHashCode();
+            }
+
+            return _hashcode;
         }
 
         public override string ToString()
@@ -132,5 +139,19 @@ public override string ToString()
         {
             return !(left == right);
         }
+
+        private static bool IsUpperAscii(string value)
+        {
+            for (int i = 0; i < value.Length; i++)
+            {
+                char c = value[i];
+                if (!(c >= 'A' && c <= 'Z'))
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
     }
 }

src/System.Net.Http/tests/FunctionalTests/HttpMethodTest.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System;
+using System.Collections.Generic;
 using System.Net;
 using System.Net.Http;
 
@@ -11,6 +12,19 @@ namespace System.Net.Http.Tests
 {
     public class HttpMethodTest
     {
+        private static readonly object[][] s_staticHttpMethods =
+        {
+            new object[] { HttpMethod.Get },
+            new object[] { HttpMethod.Put },
+            new object[] { HttpMethod.Post },
+            new object[] { HttpMethod.Delete },
+            new object[] { HttpMethod.Head },
+            new object[] { HttpMethod.Options },
+            new object[] { HttpMethod.Trace }
+        };
+
+        public static IEnumerable<object[]> StaticHttpMethods { get { return s_staticHttpMethods; } }
+
         [Fact]
         public void StaticProperties_VerifyValues_PropertyNameMatchesHttpMethodName()
         {
@@ -80,12 +94,23 @@ public void Equals_NullComparand_ReturnsFalse()
             Assert.False(HttpMethod.Trace == null);
         }
 
-        [Fact]
-        public void GetHashCode_UseCustomStringMethod_SameAsStringHashCode()
+        [Theory]
+        [InlineData("GET")]
+        [InlineData("get")]
+        [InlineData("Get")]
+        [InlineData("CUSTOM")]
+        [InlineData("cUsToM")]
+        public void GetHashCode_CustomStringMethod_SameAsStringToUpperInvariantHashCode(string input)
         {
-            string custom = "CUSTOM";
-            HttpMethod method = new HttpMethod(custom);
-            Assert.Equal(custom.GetHashCode(), method.GetHashCode());
+            HttpMethod method = new HttpMethod(input);
+            Assert.Equal(input.ToUpperInvariant().GetHashCode(), method.GetHashCode());
+        }
+
+        [Theory]
+        [MemberData("StaticHttpMethods")]
+        public void GetHashCode_StaticMethods_SameAsStringToUpperInvariantHashCode(HttpMethod method)
+        {
+            Assert.Equal(method.ToString().ToUpperInvariant().GetHashCode(), method.GetHashCode());
         }
 
         [Fact]