From f1f8bdeb09d983720b0a22aceb8e9567a0b5aaab Mon Sep 17 00:00:00 2001
From: Matt Kotsenas <matt.kotsenas@gmail.com>
Date: Wed, 4 Sep 2024 14:39:14 -0700
Subject: [PATCH] Eliminate allocs in TypeConverterCache lookup path

---
 YamlDotNet/Helpers/DictionaryExtensions.cs         |  4 ++--
 .../Serialization/Utilities/TypeConverterCache.cs  | 14 +++++---------
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/YamlDotNet/Helpers/DictionaryExtensions.cs b/YamlDotNet/Helpers/DictionaryExtensions.cs
index f5038c91..96c9fd75 100644
--- a/YamlDotNet/Helpers/DictionaryExtensions.cs
+++ b/YamlDotNet/Helpers/DictionaryExtensions.cs
@@ -26,7 +26,7 @@ namespace YamlDotNet.Helpers
 {
     internal static class DictionaryExtensions
     {
-#if NETSTANDARD2_0 || NETFRAMEWORK
+#if NETSTANDARD || NETFRAMEWORK
         public static bool TryAdd<T, V>(this System.Collections.Generic.Dictionary<T, V> dictionary, T key, V value)
         {
             if (dictionary.ContainsKey(key))
@@ -39,7 +39,7 @@ public static bool TryAdd<T, V>(this System.Collections.Generic.Dictionary<T, V>
         }
 #endif
 
-#if NETSTANDARD2_0 || NETFRAMEWORK
+#if NETSTANDARD || NETFRAMEWORK
         public static TValue GetOrAdd<TKey, TValue, TArg>(this ConcurrentDictionary<TKey, TValue> dictionary, TKey key, Func<TKey, TArg, TValue> valueFactory, TArg arg)
         {
             if (dictionary == null) { throw new ArgumentNullException(nameof(dictionary)); }
diff --git a/YamlDotNet/Serialization/Utilities/TypeConverterCache.cs b/YamlDotNet/Serialization/Utilities/TypeConverterCache.cs
index 683658ea..288a08d4 100644
--- a/YamlDotNet/Serialization/Utilities/TypeConverterCache.cs
+++ b/YamlDotNet/Serialization/Utilities/TypeConverterCache.cs
@@ -24,6 +24,7 @@
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using YamlDotNet.Helpers;
 
 namespace YamlDotNet.Serialization.Utilities
 {
@@ -52,12 +53,7 @@ public TypeConverterCache(IYamlTypeConverter[] typeConverters)
         /// <returns><see langword="true"/> if a type converter was found; <see langword="false"/> otherwise.</returns>
         public bool TryGetConverterForType(Type type, [NotNullWhen(true)] out IYamlTypeConverter? typeConverter)
         {
-            var result = cache.GetOrAdd(type, (t) =>
-            {
-                var converter = LookupTypeConverter(type);
-                var found = converter != null;
-                return (found, converter);
-            });
+            var result = cache.GetOrAdd(type, static (t, tc) => LookupTypeConverter(t, tc), typeConverters);
 
             typeConverter = result.TypeConverter;
             return result.HasMatch;
@@ -87,18 +83,18 @@ public IYamlTypeConverter GetConverterByType(Type converter)
             throw new ArgumentException($"{nameof(IYamlTypeConverter)} of type {converter.FullName} not found", nameof(converter));
         }
 
-        private IYamlTypeConverter? LookupTypeConverter(Type type)
+        private static (bool HasMatch, IYamlTypeConverter? TypeConverter) LookupTypeConverter(Type type, IYamlTypeConverter[] typeConverters)
         {
             // Intentially avoids LINQ as this is on a hot path
             foreach (var typeConverter in typeConverters)
             {
                 if (typeConverter.Accepts(type))
                 {
-                    return typeConverter;
+                    return (true, typeConverter);
                 }
             }
 
-            return null;
+            return (false, null);
         }
     }
 }