Optimize DecodeMapToType

MaxMind.Db/Decoder.cs

@@ -1,6 +1,9 @@
 #region
 
 using System;
+#if !NETSTANDARD2_0
+using System.Buffers;
+#endif
 using System.Collections;
 using System.Collections.Generic;
 using System.Numerics;
@@ -347,7 +350,15 @@ private object DecodeMapToType(
             )
         {
             var constructor = _typeAcivatorCreator.GetActivator(expectedType);
-            var parameters = constructor.DefaultParameters();
+
+#if !NETSTANDARD2_0
+            // N.B. Rent can return a larger arrays. This is fine because constructors allow arrays larger than the
+            // number of parameters.
+            object?[] parameters = ArrayPool<object?>.Shared.Rent(constructor.DefaultParameters.Length);
+#else
+            object?[] parameters = new object?[constructor.DefaultParameters.Length];
+#endif
+            constructor.DefaultParameters.CopyTo(parameters, 0);
 
             for (var i = 0; i < size; i++)
             {
@@ -370,12 +381,18 @@ private object DecodeMapToType(
             SetAlwaysCreatedParams(constructor, parameters, injectables, network);
 
             outOffset = offset;
-            return constructor.Activator(parameters);
+            object obj = constructor.Activator(parameters);
+
+#if !NETSTANDARD2_0
+            ArrayPool<object?>.Shared.Return(parameters);
+#endif
+
+            return obj;
         }
 
         private void SetAlwaysCreatedParams(
             TypeActivator constructor,
-            object[] parameters,
+            object?[] parameters,
             InjectableValues? injectables,
             Network? network
             )
@@ -385,15 +402,26 @@ private void SetAlwaysCreatedParams(
                 if (parameters[param.Position] != null) continue;
 
                 var activator = _typeAcivatorCreator.GetActivator(param.ParameterType);
-                var cstorParams = activator.DefaultParameters();
+
+#if !NETSTANDARD2_0
+                object?[] cstorParams = ArrayPool<object?>.Shared.Rent(activator.DefaultParameters.Length);
+#else
+                object?[] cstorParams = new object?[activator.DefaultParameters.Length];
+#endif
+                activator.DefaultParameters.CopyTo(cstorParams, 0);
+
                 SetInjectables(activator, cstorParams, injectables);
                 SetNetwork(activator, cstorParams, network);
                 SetAlwaysCreatedParams(activator, cstorParams, injectables, network);
                 parameters[param.Position] = activator.Activator(cstorParams);
+
+#if !NETSTANDARD2_0
+                ArrayPool<object?>.Shared.Return(cstorParams);
+#endif
             }
         }
 
-        private static void SetInjectables(TypeActivator constructor, object[] parameters, InjectableValues? injectables)
+        private static void SetInjectables(TypeActivator constructor, object?[] parameters, InjectableValues? injectables)
         {
             foreach (var item in constructor.InjectableParameters)
             {

MaxMind.Db/Key.cs

@@ -1,6 +1,8 @@
-namespace MaxMind.Db
+using System;
+
+namespace MaxMind.Db
 {
-    internal readonly struct Key
+    internal readonly struct Key : IEquatable<Key>
     {
         private readonly Buffer buffer;
         private readonly long offset;
@@ -21,15 +23,8 @@ public Key(Buffer buffer, long offset, int size)
             hashCode = code;
         }
 
-        public override bool Equals(object? obj)
+        public bool Equals(Key other)
         {
-            if ((obj == null) || !GetType().Equals(obj.GetType()))
-            {
-                return false;
-            }
-
-            var other = (Key)obj;
-
             if (size != other.size)
             {
                 return false;
@@ -42,9 +37,20 @@ public override bool Equals(object? obj)
                     return false;
                 }
             }
+
             return true;
         }
 
+        public override bool Equals(object? obj)
+        {
+            if (obj == null || typeof(Key) != obj.GetType())
+            {
+                return false;
+            }
+
+            return Equals((Key)obj);
+        }
+
         public override int GetHashCode()
         {
             return hashCode;

MaxMind.Db/ReflectionUtil.cs

@@ -8,7 +8,7 @@
 
 namespace MaxMind.Db
 {
-    internal delegate object ObjectActivator(params object[] args);
+    internal delegate object ObjectActivator(params object?[] args);
 
     internal static class ReflectionUtil
     {

MaxMind.Db/TypeAcivatorCreator.cs

@@ -11,22 +11,22 @@
 
 namespace MaxMind.Db
 {
-    internal readonly struct TypeActivator
+    internal class TypeActivator
     {
         internal readonly ObjectActivator Activator;
-        internal readonly List<ParameterInfo> AlwaysCreatedParameters;
-        private readonly object?[] _defaultParameters;
+        internal readonly ParameterInfo[] AlwaysCreatedParameters;
+        internal readonly object?[] DefaultParameters;
         internal readonly Dictionary<Key, ParameterInfo> DeserializationParameters;
-        internal readonly Dictionary<string, ParameterInfo> InjectableParameters;
-        internal readonly List<ParameterInfo> NetworkParameters;
+        internal readonly KeyValuePair<string, ParameterInfo>[] InjectableParameters;
+        internal readonly ParameterInfo[] NetworkParameters;
 
         internal TypeActivator(
             ObjectActivator activator,
             Dictionary<Key, ParameterInfo> deserializationParameters,
-            Dictionary<string, ParameterInfo> injectables,
-            List<ParameterInfo> networkParameters,
-            List<ParameterInfo> alwaysCreatedParameters
-            ) : this()
+            KeyValuePair<string, ParameterInfo>[] injectables,
+            ParameterInfo[] networkParameters,
+            ParameterInfo[] alwaysCreatedParameters
+            )
         {
             Activator = activator;
             AlwaysCreatedParameters = alwaysCreatedParameters;
@@ -35,11 +35,9 @@ List<ParameterInfo> alwaysCreatedParameters
 
             NetworkParameters = networkParameters;
             Type[] parameterTypes = deserializationParameters.Values.OrderBy(x => x.Position).Select(x => x.ParameterType).ToArray();
-            _defaultParameters = parameterTypes.Select(DefaultValue).ToArray();
+            DefaultParameters = parameterTypes.Select(DefaultValue).ToArray();
         }
 
-        internal object[] DefaultParameters() => (object[])_defaultParameters.Clone();
-
         private static object? DefaultValue(Type type)
         {
             if (type.GetTypeInfo().IsValueType && Nullable.GetUnderlyingType(type) == null)
@@ -78,15 +76,15 @@ private static TypeActivator ClassActivator(Type expectedType)
             var constructor = constructors[0];
             var parameters = constructor.GetParameters();
             var paramNameTypes = new Dictionary<Key, ParameterInfo>();
-            var injectables = new Dictionary<string, ParameterInfo>();
+            var injectables = new List<KeyValuePair<string, ParameterInfo>>();
             var networkParams = new List<ParameterInfo>();
             var alwaysCreated = new List<ParameterInfo>();
             foreach (var param in parameters)
             {
                 var injectableAttribute = param.GetCustomAttributes<InjectAttribute>().FirstOrDefault();
                 if (injectableAttribute != null)
                 {
-                    injectables.Add(injectableAttribute.ParameterName, param);
+                    injectables.Add(new KeyValuePair<string, ParameterInfo>(injectableAttribute.ParameterName, param));
                 }
                 var networkAttribute = param.GetCustomAttributes<NetworkAttribute>().FirstOrDefault();
                 if (networkAttribute != null)
@@ -113,7 +111,8 @@ private static TypeActivator ClassActivator(Type expectedType)
                 paramNameTypes.Add(new Key(new ArrayBuffer(bytes), 0, bytes.Length), param);
             }
             var activator = ReflectionUtil.CreateActivator(constructor);
-            var clsConstructor = new TypeActivator(activator, paramNameTypes, injectables, networkParams, alwaysCreated);
+            var clsConstructor = new TypeActivator(activator, paramNameTypes, injectables.ToArray(),
+                networkParams.ToArray(), alwaysCreated.ToArray());
             return clsConstructor;
         }
     }