Use less memory when generating a GuidUdi (#13090)

* Use less memory when generating a GuidUdi

* PR feedback

Co-authored-by: Sebastiaan Janssen <sebastiaan@umbraco.com>

src/Umbraco.Core/Constants-Conventions.cs

@@ -348,5 +348,10 @@ public static partial class Constants
 
             // TODO: return a list of built in types so we can use that to prevent deletion in the uI
         }
+
+        public static class Udi
+        {
+            public const string Prefix = "umb://";
+        }
     }
 }

src/Umbraco.Core/GuidUdi.cs

@@ -1,4 +1,5 @@
 using System.ComponentModel;
+using Umbraco.Extensions;
 
 namespace Umbraco.Cms.Core;
 
@@ -14,7 +15,7 @@ public class GuidUdi : Udi
     /// <param name="entityType">The entity type part of the udi.</param>
     /// <param name="guid">The guid part of the udi.</param>
     public GuidUdi(string entityType, Guid guid)
-        : base(entityType, "umb://" + entityType + "/" + guid.ToString("N")) =>
+        : base(entityType, CreateStringValue(entityType, guid)) =>
         Guid = guid;
 
     /// <summary>
@@ -57,4 +58,19 @@ public class GuidUdi : Udi
         EnsureNotRoot();
         return this;
     }
+
+    private static string CreateStringValue(ReadOnlySpan<char> entityType, Guid guid)
+    {
+        var startUdiLength = Constants.Conventions.Udi.Prefix.Length;
+        var outputSize = entityType.Length + startUdiLength + 32 + 1; //Based on the format umb://entityType/guid (32 = Guid N format, 1 = / between entityType and guid)
+        Span<char> output = stackalloc char[outputSize];
+
+        //Add all the values of the format to the output
+        Constants.Conventions.Udi.Prefix.CopyTo(output[..startUdiLength]);
+        entityType.CopyTo(output.Slice(startUdiLength, entityType.Length));
+        output[startUdiLength + entityType.Length] = '/';
+        guid.TryFormat(output.Slice(outputSize - 32, 32), out _, "N");
+
+        return new string(output);
+    }
 }

src/Umbraco.Core/StringUdi.cs

@@ -14,7 +14,7 @@ public class StringUdi : Udi
     /// <param name="entityType">The entity type part of the udi.</param>
     /// <param name="id">The string id part of the udi.</param>
     public StringUdi(string entityType, string id)
-        : base(entityType, "umb://" + entityType + "/" + EscapeUriString(id)) =>
+        : base(entityType, Constants.Conventions.Udi.Prefix + entityType + "/" + EscapeUriString(id)) =>
         Id = id;
 
     /// <summary>

tests/Umbraco.Tests.Benchmarks/GuidUdiBenchmarks.cs

@@ -0,0 +1,88 @@
+using System;
+using BenchmarkDotNet.Attributes;
+using Umbraco.Cms.Core;
+using Umbraco.Tests.Benchmarks.Config;
+
+namespace Umbraco.Tests.Benchmarks
+{
+    [QuickRunWithMemoryDiagnoserConfig]
+    public class GuidUdiBenchmarks
+    {
+        private readonly Guid _guid = Guid.NewGuid();
+        private readonly string _entityType = Constants.UdiEntityType.DocumentType;
+
+        [Benchmark(Baseline = true)]
+        public Udi CurrentInit()
+        {
+            return new OldGuidUdi(_entityType, _guid);
+        }
+
+        [Benchmark()]
+        public Udi StringPolationInit()
+        {
+            return new StringPolationGuidUdi(_entityType, _guid);
+        }
+
+        [Benchmark]
+        public Udi NewInit()
+        {
+            return new NewGuidUdi(_entityType, _guid);
+        }
+
+        public class OldGuidUdi : Udi
+        {
+            public Guid Guid { get; }
+
+            public override bool IsRoot => throw new NotImplementedException();
+
+            public OldGuidUdi(string entityType, Guid guid)
+            : base(entityType, "umb://" + entityType + "/" + guid.ToString("N")) =>
+            Guid = guid;
+        }
+
+        public class StringPolationGuidUdi : Udi
+        {
+            public Guid Guid { get; }
+
+            public override bool IsRoot => throw new NotImplementedException();
+
+            public StringPolationGuidUdi(string entityType, Guid guid)
+            : base(entityType, $"umb://{entityType}/{guid:N}") =>
+            Guid = guid;
+        }
+
+        public class NewGuidUdi : Udi
+        {
+            public Guid Guid { get; }
+
+            public override bool IsRoot => throw new NotImplementedException();
+
+            public NewGuidUdi(string entityType, Guid guid) : base(entityType, GetStringValue(entityType, guid))
+            {
+                Guid = guid;
+            }
+
+            public static string GetStringValue(ReadOnlySpan<char> entityType, Guid guid)
+            {
+                var startUdiLength = Constants.Conventions.Udi.Prefix.Length;
+                var outputSize = entityType.Length + startUdiLength + 32 + 1;
+                Span<char> output = stackalloc char[outputSize];
+
+                Constants.Conventions.Udi.Prefix.CopyTo(output[..startUdiLength]);
+                entityType.CopyTo(output.Slice(startUdiLength, entityType.Length));
+                output[startUdiLength + entityType.Length] = '/';
+                guid.TryFormat(output.Slice(outputSize - 32, 32), out _, "N");
+
+                return new string(output);
+            }
+        }
+
+        // I think we are currently bottlenecked by the 'new Udi(string)' not accepting a span. If it did, then we wouldn't have to create a string mid creation and we would be able to cut back on the allocated data
+        //
+        //|             Method |     Mean |     Error |   StdDev | Ratio | RatioSD |  Gen 0 | Allocated |
+        //|------------------- |---------:|----------:|---------:|------:|--------:|-------:|----------:|
+        //|        CurrentInit | 562.2 ns | 242.84 ns | 13.31 ns |  1.00 |    0.00 | 0.1113 |     352 B |
+        //| StringPolationInit | 589.3 ns | 530.08 ns | 29.06 ns |  1.05 |    0.07 | 0.0811 |     264 B |
+        //|            NewInit | 533.6 ns |  40.55 ns |  2.22 ns |  0.95 |    0.03 | 0.0808 |     264 B |
+    }
+}