Weaver Rpc code doesn't manually construct the message anymore. The NetworkWriter is now passed to NetworkBehaviour.SendRPCInternal, where the message is properly constructed. Reduces dependencies on NetworkConnection.SendBytes and avoids expensive GetComponent calls that the Weaver previously generated.

Unity-Technologies-networking/Runtime/ClientScene.cs

@@ -612,22 +612,21 @@ static void OnUpdateVarsMessage(NetworkMessage netMsg)
 
         static void OnRPCMessage(NetworkMessage netMsg)
         {
-            var cmdHash = (int)netMsg.reader.ReadPackedUInt32();
-            var netId = netMsg.reader.ReadNetworkId();
+            RpcMessage message = netMsg.ReadMessage<RpcMessage>();
 
-            if (LogFilter.logDebug) { Debug.Log("ClientScene::OnRPCMessage hash:" + cmdHash + " netId:" + netId); }
+            if (LogFilter.logDebug) { Debug.Log("ClientScene::OnRPCMessage hash:" + message.rpcHash + " netId:" + message.netId); }
 
             NetworkIdentity uv;
-            if (s_NetworkScene.GetNetworkIdentity(netId, out uv))
+            if (s_NetworkScene.GetNetworkIdentity(message.netId, out uv))
             {
-                uv.HandleRPC(cmdHash, netMsg.reader);
+                uv.HandleRPC(message.rpcHash, new NetworkReader(message.payload));
             }
             else
             {
                 if (LogFilter.logWarn)
                 {
-                    string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
-                    Debug.LogWarningFormat("Could not find target object with netId:{0} for RPC call {1}", netId, errorCmdName);
+                    string errorRpcName = NetworkBehaviour.GetCmdHashHandlerName(message.rpcHash);
+                    Debug.LogWarningFormat("Could not find target object with netId:{0} for RPC call {1}", message.netId, errorRpcName);
                 }
             }
         }

Unity-Technologies-networking/Runtime/Messages.cs

@@ -161,13 +161,28 @@ public override void Serialize(NetworkWriter writer)
         }
     }
 
-    /* These are not used directly but manually serialized, these are here for reference.
-    public struct RPCMessage
+    class RpcMessage : MessageBase
     {
-        public NetworkId netId;
-        public int cmdHash;
-        public byte[] payload;
+        public NetworkInstanceId netId;
+        public int rpcHash;
+        public byte[] payload; // the parameters for the Rpc function
+
+        public override void Deserialize(NetworkReader reader)
+        {
+            netId = reader.ReadNetworkId();
+            rpcHash = reader.ReadInt32(); // hash is always 4 full bytes, WritePackedInt would send 1 extra byte here
+            payload = reader.ReadBytesAndSize();
+        }
+
+        public override void Serialize(NetworkWriter writer)
+        {
+            writer.Write(netId);
+            writer.Write(rpcHash);
+            writer.WriteBytesAndSize(payload);
+        }
     }
+
+    /* These are not used directly but manually serialized, these are here for reference.
     public struct SyncEventMessage
     {
         public NetworkId netId;

Unity-Technologies-networking/Runtime/NetworkBehaviour.cs

@@ -92,7 +92,7 @@ public virtual bool InvokeCommand(int cmdHash, NetworkReader reader)
         // ----------------------------- Client RPCs --------------------------------
 
         [EditorBrowsable(EditorBrowsableState.Never)]
-        protected void SendRPCInternal(NetworkWriter writer, int channelId, string rpcName)
+        protected void SendRPCInternal(int rpcHash, NetworkWriter writer, int channelId, string rpcName)
         {
             // This cannot use NetworkServer.active, as that is not specific to this object.
             if (!isServer)
@@ -101,8 +101,13 @@ protected void SendRPCInternal(NetworkWriter writer, int channelId, string rpcNa
                 return;
             }
 
-            writer.FinishMessage();
-            NetworkServer.SendBytesToReady(gameObject, writer.ToArray(), channelId);
+            // construct the message
+            RpcMessage message = new RpcMessage();
+            message.netId = netId;
+            message.rpcHash = rpcHash;
+            message.payload = writer.ToArray();
+
+            NetworkServer.SendByChannelToReady(gameObject, (short)MsgType.Rpc, message, channelId);
 
 #if UNITY_EDITOR
             UnityEditor.NetworkDetailStats.IncrementStat(

Unity-Technologies-networking/Weaver/UNetBehaviourProcessor.cs

@@ -1368,6 +1368,18 @@ MethodDefinition ProcessTargetRpcCall(MethodDefinition md, CustomAttribute ca)
             return rpc;
         }
 
+        /* generates code like:
+        public void CallRpcTest (int param)
+        {
+            if (!NetworkServer.get_active ()) {
+                Debug.LogError ((object)"RPC Function RpcTest called on client.");
+            } else {
+                NetworkWriter writer = new NetworkWriter ();
+                writer.WritePackedUInt32((uint)param);
+                base.SendRPCInternal(Player.kRpcRpcTest, writer, 0, "RpcTest");
+            }
+        }
+        */
         MethodDefinition ProcessRpcCall(MethodDefinition md, CustomAttribute ca)
         {
             MethodDefinition rpc = new MethodDefinition("Call" +  md.Name, MethodAttributes.Public |
@@ -1389,34 +1401,17 @@ MethodDefinition ProcessRpcCall(MethodDefinition md, CustomAttribute ca)
 
             WriteCreateWriter(rpcWorker);
 
-            WriteMessageSize(rpcWorker);
-
-            WriteMessageId(rpcWorker, 2); // UNetwork.SYSTEM_RPC
-
-            // create the command id constant
+            // create the rpc id constant
             FieldDefinition rpcConstant = new FieldDefinition("kRpc" + md.Name,
                     FieldAttributes.Static | FieldAttributes.Private,
                     Weaver.int32Type);
             m_td.Fields.Add(rpcConstant);
 
-            // write command constant
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Ldloc_0));
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Ldsfld, rpcConstant));
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Callvirt, Weaver.NetworkWriterWritePacked32));
-
-            // write this.unetView.netId
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Ldloc_0));
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Ldarg_0));
-            // load unetviewfield
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Call, Weaver.getComponentReference));
-            // load and write netId field
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Callvirt, Weaver.getUNetIdReference));
-            rpcWorker.Append(rpcWorker.Create(OpCodes.Callvirt, Weaver.NetworkWriterWriteNetworkInstanceId));
-
+            // write all the arguments that the user passed to the Rpc call
             if (!WriteArguments(rpcWorker, md, "RPC", false))
                 return null;
 
-            // find channel for SyncEvent
+            // find channel for Rpc
             int channel = 0;
             foreach (var field in ca.Fields)
             {
@@ -1435,6 +1430,7 @@ MethodDefinition ProcessRpcCall(MethodDefinition md, CustomAttribute ca)
 
             // invoke SendInternal and return
             rpcWorker.Append(rpcWorker.Create(OpCodes.Ldarg_0)); // this
+            rpcWorker.Append(rpcWorker.Create(OpCodes.Ldsfld, rpcConstant)); // rpcHash
             rpcWorker.Append(rpcWorker.Create(OpCodes.Ldloc_0)); // writer
             rpcWorker.Append(rpcWorker.Create(OpCodes.Ldc_I4, channel)); // QoS transport channel (reliable/unreliable)
             rpcWorker.Append(rpcWorker.Create(OpCodes.Ldstr, rpcName));