feat: Update UTP to 1.4 and add ability to set UTP's MTU (#2716)

Author: simon-lemay-unity

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -34,6 +34,8 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 ### Changed
 
+- Updated dependency on `com.unity.transport` to version 1.4.0. (#2716)
+
 ## [1.6.0] - 2023-08-09
 
 ### Added

com.unity.netcode.gameobjects/Runtime/Transports/UTP/BatchedSendQueue.cs

@@ -242,7 +242,7 @@ public int FillWriterWithMessages(ref DataStreamWriter writer)
         /// Fill the given <see cref="DataStreamWriter"/> with as many bytes from the queue as
         /// possible, disregarding message boundaries.
         /// </summary>
-        ///<remarks>
+        /// <remarks>
         /// This does NOT actually consume anything from the queue. That is, calling this method
         /// does not reduce the length of the queue. Callers are expected to call
         /// <see cref="Consume"/> with the value returned by this method afterwards if the data can
@@ -252,15 +252,17 @@ public int FillWriterWithMessages(ref DataStreamWriter writer)
         /// this could lead to reading messages from a corrupted queue.
         /// </remarks>
         /// <param name="writer">The <see cref="DataStreamWriter"/> to write to.</param>
+        /// <param name="maxBytes">Max number of bytes to copy (0 means writer capacity).</param>
         /// <returns>How many bytes were written to the writer.</returns>
-        public int FillWriterWithBytes(ref DataStreamWriter writer)
+        public int FillWriterWithBytes(ref DataStreamWriter writer, int maxBytes = 0)
         {
             if (!IsCreated || Length == 0)
             {
                 return 0;
             }
 
-            var copyLength = Math.Min(writer.Capacity, Length);
+            var maxLength = maxBytes == 0 ? writer.Capacity : maxBytes;
+            var copyLength = Math.Min(maxLength, Length);
 
             unsafe
             {

com.unity.netcode.gameobjects/Runtime/Transports/UTP/UnityTransport.cs

@@ -727,6 +727,7 @@ private struct SendBatchedMessagesJob : IJob
             public SendTarget Target;
             public BatchedSendQueue Queue;
             public NetworkPipeline ReliablePipeline;
+            public int MTU;
 
             public void Execute()
             {
@@ -749,7 +750,7 @@ public void Execute()
                     // in the stream (the send queue does that automatically) we are sure they'll be
                     // reassembled properly at the other end. This allows us to lift the limit of ~44KB
                     // on reliable payloads (because of the reliable window size).
-                    var written = pipeline == ReliablePipeline ? Queue.FillWriterWithBytes(ref writer) : Queue.FillWriterWithMessages(ref writer);
+                    var written = pipeline == ReliablePipeline ? Queue.FillWriterWithBytes(ref writer, MTU) : Queue.FillWriterWithMessages(ref writer);
 
                     result = Driver.EndSend(writer);
                     if (result == written)
@@ -788,7 +789,8 @@ private void SendBatchedMessages(SendTarget sendTarget, BatchedSendQueue queue)
                 Driver = m_Driver.ToConcurrent(),
                 Target = sendTarget,
                 Queue = queue,
-                ReliablePipeline = m_ReliableSequencedPipeline
+                ReliablePipeline = m_ReliableSequencedPipeline,
+                MTU = NetworkManager ? NetworkManager.GetPeerMTU(sendTarget.ClientId) + m_Driver.MaxHeaderSize(sendTarget.NetworkPipeline) : 0,
             }.Run();
         }
 

com.unity.netcode.gameobjects/package.json

@@ -6,6 +6,6 @@
     "unity": "2020.3",
     "dependencies": {
         "com.unity.nuget.mono-cecil": "1.10.1",
-        "com.unity.transport": "1.3.4"
+        "com.unity.transport": "1.4.0"
     }
 }