fix: Dispose of PooledBitStream used in the MessageBatcher (#436)

* fix: Dispose of PooledBitStream used in the MessageBatcher, also stores only the FrameQueueItem's channel, as opposed to the whole FrameQueueItem
MTT-193 MTT-250

* perf: avoid transport issues by dropping message size

* style: using 'using' instead of manually 'dispose'ing

Co-authored-by: Jeffrey Rainy <jeffrey.rainy@unity3d.com>
Co-authored-by: M. Fatih MAR <mfatihmar@gmail.com>

Author: 3 people

com.unity.multiplayer.mlapi/Runtime/Core/MessageBatcher.cs

@@ -13,7 +13,7 @@ class MessageBatcher
     {
         public class SendStream
         {
-            public FrameQueueItem Item;
+            public string channel;
             public PooledBitStream Stream = PooledBitStream.Get();
             public bool Empty = true;
         }
@@ -114,7 +114,7 @@ public void QueueItem(in FrameQueueItem item)
                 if (SendDict[clientId].Empty)
                 {
                     SendDict[clientId].Empty = false;
-                    SendDict[clientId].Item = item;
+                    SendDict[clientId].channel = item.Channel;
                     Writer.SetStream(SendDict[clientId].Stream);
 
                     Writer.WriteBit(false); // Encrypted
@@ -187,6 +187,7 @@ public void SendItems(int threshold, SendCallbackType sendCallback)
         /// <param name="receiveTime"> the packet receive time to pass back to callback</param>
         public int ReceiveItems(in BitStream messageStream, ReceiveCallbackType receiveCallback, MLAPI.RPCQueueManager.QueueItemType messageType, ulong clientId, float receiveTime)
         {
+            using PooledBitStream copy = PooledBitStream.Get();
             do
             {
                 // read the length of the next RPC
@@ -200,7 +201,6 @@ public int ReceiveItems(in BitStream messageStream, ReceiveCallbackType receiveC
 
                 // copy what comes after current stream position
                 long pos = messageStream.Position;
-                BitStream copy = PooledBitStream.Get();
                 copy.SetLength(rpcSize);
                 copy.Position = 0;
                 Buffer.BlockCopy(messageStream.GetBuffer(), (int)pos, copy.GetBuffer(), 0, rpcSize);

com.unity.multiplayer.mlapi/Runtime/Core/RPCQueue/RPCQueueProcessing.cs

@@ -25,7 +25,7 @@ internal class RPCQueueProcessing
 #endif
         // Batcher object used to manage the RPC batching on the send side
         private MessageBatcher batcher = new MessageBatcher();
-        private int BatchThreshold = 1000;
+        private int BatchThreshold = 512;
 
         //NSS-TODO: Need to determine how we want to handle all other MLAPI send types
         //Temporary place to keep internal MLAPI messages
@@ -208,7 +208,7 @@ private static void SendCallback(ulong clientId, MLAPI.MessageBatcher.SendStream
             ArraySegment<byte> sendBuffer = new ArraySegment<byte>(bytes, 0, length);
 
             NetworkingManager.Singleton.NetworkConfig.NetworkTransport.Send(clientId, sendBuffer,
-                string.IsNullOrEmpty(sendStream.Item.Channel) ? "MLAPI_DEFAULT_MESSAGE" : sendStream.Item.Channel);
+                string.IsNullOrEmpty(sendStream.channel) ? "MLAPI_DEFAULT_MESSAGE" : sendStream.channel);
         }
     }
 }