force Singleton for some classes

Author: kerryjiang

src/SuperSocket.MySQL/MySQLConnection.cs

@@ -24,28 +24,14 @@ public class MySQLConnection : EasyClient<MySQLPacket>
         public bool IsAuthenticated { get; private set; }
 
         public MySQLConnection(string host, int port, string userName, string password)
-            : this(new MySQLPacketFactory()
-                .RegisterPacketType<HandshakePacket>(0x0A)
-                .RegisterPacketType<HandshakeResponsePacket>(0x00)
-                .RegisterPacketType<OKPacket>(0x00)
-                .RegisterPacketType<ErrorPacket>(0xFF))
+            : base(new MySQLPacketFilter(MySQLPacketDecoder.Singleton))
         {
             _host = host ?? throw new ArgumentNullException(nameof(host));
             _port = port > 0 ? port : DefaultPort;
             _userName = userName ?? throw new ArgumentNullException(nameof(userName));
             _password = password ?? throw new ArgumentNullException(nameof(password));
         }
 
-        internal MySQLConnection(IMySQLPacketFactory mySQLPacketFactory)
-            : this(new MySQLPacketDecoder(mySQLPacketFactory))
-        {
-        }
-
-        internal MySQLConnection(IPackageDecoder<MySQLPacket> packageDecoder)
-            : base(new MySQLPacketFilter(packageDecoder))
-        {
-        }
-
         public async Task ConnectAsync(CancellationToken cancellationToken = default)
         {
             if (string.IsNullOrEmpty(_host))

src/SuperSocket.MySQL/MySQLPacketDecoder.cs

@@ -6,9 +6,15 @@ namespace SuperSocket.MySQL
 {
     internal class MySQLPacketDecoder : IPackageDecoder<MySQLPacket>
     {
+        public static MySQLPacketDecoder Singleton { get; }
+        static MySQLPacketDecoder()
+        {
+            Singleton = new MySQLPacketDecoder(MySQLPacketFactory.Singleton);
+        }
+
         private readonly IMySQLPacketFactory _packetFactory;
 
-        public MySQLPacketDecoder(IMySQLPacketFactory packetFactory)
+        private MySQLPacketDecoder(IMySQLPacketFactory packetFactory)
         {
             _packetFactory = packetFactory ?? throw new ArgumentNullException(nameof(packetFactory));
         }

src/SuperSocket.MySQL/MySQLPacketFactory.cs

@@ -2,14 +2,31 @@
 using System.Buffers;
 using System.Collections.Generic;
 using System.IO;
+using SuperSocket.MySQL.Packets;
 
 namespace SuperSocket.MySQL
 {
     internal class MySQLPacketFactory : IMySQLPacketFactory
     {
-        private readonly Dictionary<int, Func<MySQLPacket>> _packetCreators = new ();
+        public static MySQLPacketFactory Singleton { get; }
 
-        public MySQLPacketFactory RegisterPacketType<TMySQLPacket>(int packageType)
+        static MySQLPacketFactory()
+        {
+            Singleton = new MySQLPacketFactory()
+                .RegisterPacketType<HandshakePacket>(0x0A)
+                .RegisterPacketType<HandshakeResponsePacket>(0x00)
+                .RegisterPacketType<OKPacket>(0x00)
+                .RegisterPacketType<ErrorPacket>(0xFF);
+        }
+
+        private readonly Dictionary<int, Func<MySQLPacket>> _packetCreators = new();
+
+        private MySQLPacketFactory()
+        {
+            // Private constructor to enforce singleton pattern
+        }
+
+        private MySQLPacketFactory RegisterPacketType<TMySQLPacket>(int packageType)
             where TMySQLPacket : MySQLPacket, new()
         {
             _packetCreators[packageType] = () => new TMySQLPacket();