Fast React ID Generator

src/React.Core/ReactComponent.cs

@@ -102,7 +102,7 @@ public ReactComponent(IReactEnvironment environment, IReactSiteConfiguration con
 			_environment = environment;
 			_configuration = configuration;
 			ComponentName = componentName;
-			ContainerId = string.IsNullOrEmpty(containerId) ? GenerateId() : containerId;
+			ContainerId = string.IsNullOrEmpty(containerId) ? ReactIdGenerator.Generate() : containerId;
 			ContainerTag = "div";
 		}
 
@@ -229,14 +229,5 @@ internal static void EnsureComponentNameValid(string componentName)
 				));
 			}
 		}
-
-		/// <summary>
-		/// Generates a unique identifier for this component, if one was not passed in.
-		/// </summary>
-		/// <returns></returns>
-		private static string GenerateId()
-		{
-			return "react_" + Guid.NewGuid().ToShortGuid();
-		}
 	}
 }

src/React.Core/ReactIdGenerator.cs

@@ -0,0 +1,62 @@
+/*
+ *  Copyright (c) 2016-Present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant 
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+using System;
+using System.Threading;
+
+namespace React
+{
+	/// <summary>
+	/// Extension methods relating to GUIDs.
+	/// </summary>
+	public static class ReactIdGenerator
+	{
+		private static readonly string _encode32Chars = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
+
+		private static long _random = DateTime.UtcNow.Ticks;
+
+		private static readonly char[] reactPrefix = "react_".ToCharArray();
+
+		[ThreadStatic]
+		private static char[] _chars;
+
+		/// <summary>
+		/// Returns a short react identifier starts with "react_".
+		/// </summary>
+		/// <returns></returns>
+		public static string Generate()
+		{
+			var chars = _chars;
+			if (chars == null)
+			{
+				_chars = chars = new char[19];
+				Array.Copy(reactPrefix, 0, chars, 0, reactPrefix.Length);
+			}
+
+			var id = Interlocked.Increment(ref _random);
+
+			//reactPrefix.Length == 6
+			chars[6] = _encode32Chars[(int)(id >> 60) & 31];
+			chars[7] = _encode32Chars[(int)(id >> 55) & 31];
+			chars[8] = _encode32Chars[(int)(id >> 50) & 31];
+			chars[9] = _encode32Chars[(int)(id >> 45) & 31];
+			chars[10] = _encode32Chars[(int)(id >> 40) & 31];
+			chars[11] = _encode32Chars[(int)(id >> 35) & 31];
+			chars[12] = _encode32Chars[(int)(id >> 30) & 31];
+			chars[13] = _encode32Chars[(int)(id >> 25) & 31];
+			chars[14] = _encode32Chars[(int)(id >> 20) & 31];
+			chars[15] = _encode32Chars[(int)(id >> 15) & 31];
+			chars[16] = _encode32Chars[(int)(id >> 10) & 31];
+			chars[17] = _encode32Chars[(int)(id >> 5) & 31];
+			chars[18] = _encode32Chars[(int)id & 31];
+
+			return new string(chars, 0, 19);
+		}
+	}
+}

tests/React.Tests/Core/ReactIdGeneratorTests.cs

@@ -0,0 +1,42 @@
+/*
+ *  Copyright (c) 2016-Present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant 
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+using System;
+using Xunit;
+
+namespace React.Tests.Core
+{
+	public class ReactIdGeneratorTests
+	{
+		[Fact]
+		public void GuidShouldHaveFixedRange()
+		{
+			var shortGuid = ReactIdGenerator.Generate();
+
+			Assert.Equal(19, shortGuid.Length);
+		}
+
+		[Fact]
+		public void ShouldStartsWithReact()
+		{
+			var shortGuid = ReactIdGenerator.Generate();
+
+			Assert.StartsWith("react_", shortGuid);
+		}
+
+		[Fact]
+		public void TwoGuidsShouldNotEqual()
+		{
+			var shortGuid1 = ReactIdGenerator.Generate();
+			var shortGuid2 = ReactIdGenerator.Generate();
+
+			Assert.NotEqual(shortGuid1, shortGuid2);
+		}
+	}
+}