Introduce EnumCache to reduce performance impact of reflection

Author: mibac138

Source/Common/ByteReader.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Text;
+using Multiplayer.Common.Util;
 
 namespace Multiplayer.Common
 {
@@ -139,7 +140,7 @@ public virtual ulong[] ReadPrefixedULongs()
 
         public virtual T ReadEnum<T>() where T : Enum
         {
-            var values = Enum.GetValues(typeof(T));
+            var values = EnumCache.GetValues(typeof(T));
             ushort enumIndex = values.Length switch
             {
                 <= byte.MaxValue => ReadByte(),

Source/Common/ByteWriter.cs

@@ -4,6 +4,7 @@
 using System.IO;
 using System.Runtime.CompilerServices;
 using System.Text;
+using Multiplayer.Common.Util;
 
 namespace Multiplayer.Common
 {
@@ -85,7 +86,7 @@ public virtual ByteWriter WriteString(string? s)
 
         public virtual void WriteEnum<T>(T value) where T : Enum
         {
-            var values = Enum.GetValues(value.GetType());
+            var values = EnumCache.GetValues(value.GetType());
             var index = Array.IndexOf(values, value);
             switch (values.Length)
             {

Source/Common/ScheduledCommand.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 
 namespace Multiplayer.Common
 {
@@ -32,7 +31,8 @@ public ScheduledCommand(CommandType type, int ticks, int factionId, int mapId, i
         public static byte[] Serialize(ScheduledCommand cmd)
         {
             ByteWriter writer = new ByteWriter();
-            writer.WriteEnum(cmd.type);
+            // Use WriteByte directly instead of WriteEnum for better performance, as this is frequently used.
+            writer.WriteByte((byte)cmd.type);
             writer.WriteInt32(cmd.ticks);
             writer.WriteInt32(cmd.factionId);
             writer.WriteInt32(cmd.mapId);
@@ -44,7 +44,8 @@ public static byte[] Serialize(ScheduledCommand cmd)
 
         public static ScheduledCommand Deserialize(ByteReader data)
         {
-            CommandType cmd = data.ReadEnum<CommandType>();
+            // Use ReadByte directly instead of ReadEnum for better performance, as this is frequently used.
+            CommandType cmd = (CommandType)data.ReadByte();
             int ticks = data.ReadInt32();
             int factionId = data.ReadInt32();
             int mapId = data.ReadInt32();

Source/Common/Util/EnumCache.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Concurrent;
+
+namespace Multiplayer.Common.Util;
+
+internal static class EnumCache
+{
+    private static readonly ConcurrentDictionary<Type, Array> Cache = new();
+
+    public static Array GetValues(Type enumType) => Cache.GetOrAdd(enumType, Enum.GetValues);
+}