perf: Adding buffer for local connection (#1621)

* Using writer for local connection

LocalConnectionBuffer

* removing assert

* fixing error and cleaning up code

* removing old queue

* tests for LocalConnectionBuffer

* removing field

* removing extra lines

* Update LocalConnections.cs

removing empty line

* adding comment for packet count

Assets/Mirror/Runtime/LocalConnections.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using UnityEngine;
 
 namespace Mirror
@@ -18,11 +17,8 @@ public ULocalConnectionToClient() : base(0)
 
         internal override bool Send(ArraySegment<byte> segment, int channelId = Channels.DefaultReliable)
         {
-            // LocalConnection doesn't support allocation-free sends yet.
-            // previously we allocated in Mirror. now we do it here.
-            byte[] data = new byte[segment.Count];
-            Array.Copy(segment.Array, segment.Offset, data, 0, segment.Count);
-            connectionToServer.packetQueue.Enqueue(data);
+            connectionToServer.buffer.Write(segment);
+
             return true;
         }
 
@@ -44,16 +40,48 @@ public override void Disconnect()
         }
     }
 
+    internal class LocalConnectionBuffer
+    {
+        readonly NetworkWriter writer = new NetworkWriter();
+        readonly NetworkReader reader = new NetworkReader(default(ArraySegment<byte>));
+        // The buffer is atleast 1500 bytes long. So need to keep track of
+        // packet count to know how many ArraySegments are in the buffer
+        int packetCount;
+
+        public void Write(ArraySegment<byte> segment)
+        {
+            writer.WriteBytesAndSizeSegment(segment);
+            packetCount++;
+
+            // update buffer incase writer's length has changed
+            reader.buffer = writer.ToArraySegment();
+        }
+
+        public bool HasPackets()
+        {
+            return packetCount > 0;
+        }
+        public ArraySegment<byte> GetNextPacket()
+        {
+            ArraySegment<byte> packet = reader.ReadBytesAndSizeSegment();
+            packetCount--;
+
+            return packet;
+        }
+
+        public void ResetBuffer()
+        {
+            writer.SetLength(0);
+            reader.Position = 0;
+        }
+    }
+
     // a localClient's connection TO a server.
     // send messages on this connection causes the server's handler function to be invoked directly.
     internal class ULocalConnectionToServer : NetworkConnectionToServer
     {
         internal ULocalConnectionToClient connectionToClient;
-
-        // local client in host mode might call Cmds/Rpcs during Update, but we
-        // want to apply them in LateUpdate like all other Transport messages
-        // to avoid race conditions. keep packets in Queue until LateUpdate.
-        internal Queue<byte[]> packetQueue = new Queue<byte[]>();
+        internal readonly LocalConnectionBuffer buffer = new LocalConnectionBuffer();
 
         public override string address => "localhost";
 
@@ -73,13 +101,16 @@ internal override bool Send(ArraySegment<byte> segment, int channelId = Channels
         internal void Update()
         {
             // process internal messages so they are applied at the correct time
-            while (packetQueue.Count > 0)
+            while (buffer.HasPackets())
             {
-                byte[] packet = packetQueue.Dequeue();
+                ArraySegment<byte> packet = buffer.GetNextPacket();
+
                 // Treat host player messages exactly like connected client
                 // to avoid deceptive / misleading behavior differences
-                TransportReceive(new ArraySegment<byte>(packet), Channels.DefaultReliable);
+                TransportReceive(packet, Channels.DefaultReliable);
             }
+
+            buffer.ResetBuffer();
         }
 
         /// <summary>

Assets/Mirror/Tests/Editor/LocalConnectionBufferTest.cs

@@ -0,0 +1,142 @@
+using System;
+using NUnit.Framework;
+
+namespace Mirror.Tests
+{
+    public class LocalConnectionBufferTest
+    {
+        readonly LocalConnectionBuffer buffer = new LocalConnectionBuffer();
+
+        [TearDown]
+        public void TearDown()
+        {
+            buffer.ResetBuffer();
+        }
+
+        [Test]
+        public void BufferHasPacketsAfterWriter()
+        {
+            using (PooledNetworkWriter writer = NetworkWriterPool.GetWriter())
+            {
+                writer.WriteString("Some Message");
+
+                buffer.Write(writer.ToArraySegment());
+            }
+
+            Assert.IsTrue(buffer.HasPackets());
+        }
+        [Test]
+        public void BufferHasNoPacketsAfterWriteAndReading()
+        {
+            using (PooledNetworkWriter writer = NetworkWriterPool.GetWriter())
+            {
+                writer.WriteString("Some Message");
+
+                buffer.Write(writer.ToArraySegment());
+            }
+            ArraySegment<byte> package = buffer.GetNextPacket();
+
+
+            Assert.IsFalse(buffer.HasPackets());
+        }
+        [Test]
+        public void BufferCanWriteAndReadPackages()
+        {
+            const string expectedMessage = "Some Message";
+            const float expectedValue = 46.8f;
+            using (PooledNetworkWriter writer = NetworkWriterPool.GetWriter())
+            {
+                writer.WriteString(expectedMessage);
+                writer.WriteSingle(expectedValue);
+
+                buffer.Write(writer.ToArraySegment());
+            }
+            ArraySegment<byte> package = buffer.GetNextPacket();
+
+            string message;
+            float value;
+            using (PooledNetworkReader reader = NetworkReaderPool.GetReader(package))
+            {
+                message = reader.ReadString();
+                value = reader.ReadSingle();
+            }
+
+            Assert.That(message, Is.EqualTo(expectedMessage));
+            Assert.That(value, Is.EqualTo(expectedValue));
+        }
+        [Test]
+        public void BufferReturnsMutliplePacketsInTheOrderTheyWereWriten()
+        {
+            const string expectedMessage1 = "first Message";
+            const string expectedMessage2 = "second Message";
+            using (PooledNetworkWriter writer = NetworkWriterPool.GetWriter())
+            {
+                writer.WriteString(expectedMessage1);
+
+                buffer.Write(writer.ToArraySegment());
+            }
+
+            using (PooledNetworkWriter writer = NetworkWriterPool.GetWriter())
+            {
+                writer.WriteString(expectedMessage2);
+
+                buffer.Write(writer.ToArraySegment());
+            }
+
+            string message1;
+            string message2;
+            ArraySegment<byte> package1 = buffer.GetNextPacket();
+
+            using (PooledNetworkReader reader = NetworkReaderPool.GetReader(package1))
+            {
+                message1 = reader.ReadString();
+            }
+
+            Assert.IsTrue(buffer.HasPackets());
+            ArraySegment<byte> package2 = buffer.GetNextPacket();
+
+            using (PooledNetworkReader reader = NetworkReaderPool.GetReader(package2))
+            {
+                message2 = reader.ReadString();
+            }
+
+            Assert.That(message1, Is.EqualTo(expectedMessage1));
+            Assert.That(message2, Is.EqualTo(expectedMessage2));
+        }
+        [Test]
+        public void BufferCanWriteReadMorePackageAfterCallingReset()
+        {
+            const string expectedMessage = "Some Message";
+            const float expectedValue = 46.8f;
+
+            for (int i = 0; i < 5; i++)
+            {
+                using (PooledNetworkWriter writer = NetworkWriterPool.GetWriter())
+                {
+                    writer.WriteInt32(i);
+                    writer.WriteString(expectedMessage);
+                    writer.WriteSingle(expectedValue);
+
+                    buffer.Write(writer.ToArraySegment());
+                }
+                ArraySegment<byte> package = buffer.GetNextPacket();
+
+                int index;
+                string message;
+                float value;
+                using (PooledNetworkReader reader = NetworkReaderPool.GetReader(package))
+                {
+                    index = reader.ReadInt32();
+                    message = reader.ReadString();
+                    value = reader.ReadSingle();
+                }
+
+                Assert.That(index, Is.EqualTo(i));
+                Assert.That(message, Is.EqualTo(expectedMessage));
+                Assert.That(value, Is.EqualTo(expectedValue));
+
+                buffer.ResetBuffer();
+            }
+        }
+    }
+}