add kcp

Src/UnityPluginsSupport/KumoKyaku/Kcp/KcpOutputWriter.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Buffers;
+using System.Collections.Generic;
+using System.Text;
+
+namespace System.Net.Sockets.Kcp
+{
+    public abstract class KcpOutputWriter : IKcpOutputWriter
+    {
+        public int UnflushedBytes { get; set; }
+        public IMemoryOwner<byte> MemoryOwner { get; set; }
+        public void Flush()
+        {
+            Output(MemoryOwner, UnflushedBytes);
+            MemoryOwner = null;
+            UnflushedBytes = 0;
+        }
+
+        public void Advance(int count)
+        {
+            UnflushedBytes += count;
+        }
+
+        public Memory<byte> GetMemory(int sizeHint = 0)
+        {
+            if (MemoryOwner == null)
+            {
+                MemoryOwner = MemoryPool<byte>.Shared.Rent(2048);
+            }
+            return MemoryOwner.Memory.Slice(UnflushedBytes);
+        }
+
+        public Span<byte> GetSpan(int sizeHint = 0)
+        {
+            if (MemoryOwner == null)
+            {
+                MemoryOwner = MemoryPool<byte>.Shared.Rent(2048);
+            }
+            return MemoryOwner.Memory.Span.Slice(UnflushedBytes);
+        }
+
+        /// <summary>
+        /// Socket发送是要pin byte[],为了不阻塞KcpFlush，动态缓存是必须的。
+        /// </summary>
+        /// <param name="buffer"></param>
+        /// <param name="avalidLength"></param>
+        public abstract void Output(IMemoryOwner<byte> buffer, int avalidLength);
+    }
+}
+
+
+
+