perf: Remove reflection from NetworkBehaviour code to improve performance. [MTT-1968] (#2522)

* perf: Remove reflection from NetworkBehaviour code to improve performance.

* changelog

* - Added some comments to clarify some ILPP code
- Added an extra error handler to catch an edge case I missed before
- Added a bit more info to the changelog
- Fixed testproject-tools-integration tests

* Apply suggestions from code review

Co-authored-by: Fatih Mar <mfatihmar@gmail.com>

---------

Co-authored-by: Fatih Mar <mfatihmar@gmail.com>

Author: ShadauxCat

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -19,6 +19,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 - Fixed some errors that could occur if a connection is lost and the loss is detected when attempting to write to the socket. (#2495)
 
 ## Changed
+- Improved performance of NetworkBehaviour initialization by replacing reflection when initializing NetworkVariables with compile-time code generation, which should help reduce hitching during additive scene loads. (#2522)
 
 
 ## [1.4.0] - 2023-04-10

com.unity.netcode.gameobjects/Editor/CodeGen/CodeGenHelpers.cs

@@ -10,6 +10,7 @@
 using Unity.CompilationPipeline.Common.Diagnostics;
 using Unity.CompilationPipeline.Common.ILPostProcessing;
 using UnityEngine;
+using Object = System.Object;
 
 namespace Unity.Netcode.Editor.CodeGen
 {
@@ -112,6 +113,60 @@ public static string FullNameWithGenericParameters(this TypeReference typeRefere
 
             return name;
         }
+        public static TypeReference MakeGenericType(this TypeReference self, params TypeReference[] arguments)
+        {
+            if (self.GenericParameters.Count != arguments.Length)
+            {
+                throw new ArgumentException();
+            }
+
+            var instance = new GenericInstanceType(self);
+            foreach (var argument in arguments)
+            {
+                instance.GenericArguments.Add(argument);
+            }
+
+            return instance;
+        }
+
+        public static MethodReference MakeGeneric(this MethodReference self, params TypeReference[] arguments)
+        {
+            var reference = new MethodReference(self.Name, self.ReturnType)
+            {
+                DeclaringType = self.DeclaringType.MakeGenericType(arguments),
+                HasThis = self.HasThis,
+                ExplicitThis = self.ExplicitThis,
+                CallingConvention = self.CallingConvention,
+            };
+
+            foreach (var parameter in self.Parameters)
+            {
+                reference.Parameters.Add(new ParameterDefinition(parameter.ParameterType));
+            }
+
+            foreach (var generic_parameter in self.GenericParameters)
+            {
+                reference.GenericParameters.Add(new GenericParameter(generic_parameter.Name, reference));
+            }
+
+            return reference;
+        }
+
+        public static bool IsSubclassOf(this TypeReference typeReference, TypeReference baseClass)
+        {
+            var type = typeReference.Resolve();
+            if (type.BaseType == null || type.BaseType.Name == nameof(Object))
+            {
+                return false;
+            }
+
+            if (type.BaseType.Resolve() == baseClass.Resolve())
+            {
+                return true;
+            }
+
+            return type.BaseType.IsSubclassOf(baseClass);
+        }
 
         public static bool HasInterface(this TypeReference typeReference, string interfaceTypeFullName)
         {

com.unity.netcode.gameobjects/Editor/CodeGen/NetworkBehaviourILPP.cs

@@ -166,6 +166,11 @@ private void CreateNetworkVariableTypeInitializers(AssemblyDefinition assembly)
 
                     foreach (var type in m_WrappedNetworkVariableTypes)
                     {
+                        if (type.Resolve() == null)
+                        {
+                            continue;
+                        }
+
                         if (IsSpecialCaseType(type))
                         {
                             continue;
@@ -251,11 +256,15 @@ private void CreateNetworkVariableTypeInitializers(AssemblyDefinition assembly)
         private FieldReference m_NetworkManager_rpc_name_table_FieldRef;
         private MethodReference m_NetworkManager_rpc_name_table_Add_MethodRef;
         private TypeReference m_NetworkBehaviour_TypeRef;
+        private TypeReference m_NetworkVariableBase_TypeRef;
+        private MethodReference m_NetworkVariableBase_Initialize_MethodRef;
+        private MethodReference m_NetworkBehaviour___nameNetworkVariable_MethodRef;
         private MethodReference m_NetworkBehaviour_beginSendServerRpc_MethodRef;
         private MethodReference m_NetworkBehaviour_endSendServerRpc_MethodRef;
         private MethodReference m_NetworkBehaviour_beginSendClientRpc_MethodRef;
         private MethodReference m_NetworkBehaviour_endSendClientRpc_MethodRef;
         private FieldReference m_NetworkBehaviour_rpc_exec_stage_FieldRef;
+        private FieldReference m_NetworkBehaviour_NetworkVariableFields_FieldRef;
         private MethodReference m_NetworkBehaviour_getNetworkManager_MethodRef;
         private MethodReference m_NetworkBehaviour_getOwnerClientId_MethodRef;
         private MethodReference m_NetworkHandlerDelegateCtor_MethodRef;
@@ -275,6 +284,9 @@ private void CreateNetworkVariableTypeInitializers(AssemblyDefinition assembly)
         private MethodReference m_NetworkVariableSerializationTypes_InitializeEqualityChecker_UnmanagedValueEquals_MethodRef;
         private MethodReference m_NetworkVariableSerializationTypes_InitializeEqualityChecker_ManagedClassEquals_MethodRef;
 
+        private MethodReference m_ExceptionCtorMethodReference;
+        private MethodReference m_List_NetworkVariableBase_Add;
+
         private MethodReference m_BytePacker_WriteValueBitPacked_Short_MethodRef;
         private MethodReference m_BytePacker_WriteValueBitPacked_UShort_MethodRef;
         private MethodReference m_BytePacker_WriteValueBitPacked_Int_MethodRef;
@@ -348,12 +360,17 @@ private void CreateNetworkVariableTypeInitializers(AssemblyDefinition assembly)
         private const string k_NetworkManager_rpc_name_table = nameof(NetworkManager.__rpc_name_table);
 
         private const string k_NetworkBehaviour_rpc_exec_stage = nameof(NetworkBehaviour.__rpc_exec_stage);
+        private const string k_NetworkBehaviour_NetworkVariableFields = nameof(NetworkBehaviour.NetworkVariableFields);
         private const string k_NetworkBehaviour_beginSendServerRpc = nameof(NetworkBehaviour.__beginSendServerRpc);
         private const string k_NetworkBehaviour_endSendServerRpc = nameof(NetworkBehaviour.__endSendServerRpc);
         private const string k_NetworkBehaviour_beginSendClientRpc = nameof(NetworkBehaviour.__beginSendClientRpc);
         private const string k_NetworkBehaviour_endSendClientRpc = nameof(NetworkBehaviour.__endSendClientRpc);
+        private const string k_NetworkBehaviour___initializeVariables = nameof(NetworkBehaviour.__initializeVariables);
         private const string k_NetworkBehaviour_NetworkManager = nameof(NetworkBehaviour.NetworkManager);
         private const string k_NetworkBehaviour_OwnerClientId = nameof(NetworkBehaviour.OwnerClientId);
+        private const string k_NetworkBehaviour___nameNetworkVariable = nameof(NetworkBehaviour.__nameNetworkVariable);
+
+        private const string k_NetworkVariableBase_Initialize = nameof(NetworkVariableBase.Initialize);
 
         private const string k_RpcAttribute_Delivery = nameof(RpcAttribute.Delivery);
         private const string k_ServerRpcAttribute_RequireOwnership = nameof(ServerRpcAttribute.RequireOwnership);
@@ -379,6 +396,7 @@ private bool ImportReferences(ModuleDefinition moduleDefinition)
 
             TypeDefinition networkManagerTypeDef = null;
             TypeDefinition networkBehaviourTypeDef = null;
+            TypeDefinition networkVariableBaseTypeDef = null;
             TypeDefinition networkHandlerDelegateTypeDef = null;
             TypeDefinition rpcParamsTypeDef = null;
             TypeDefinition serverRpcParamsTypeDef = null;
@@ -402,6 +420,12 @@ private bool ImportReferences(ModuleDefinition moduleDefinition)
                     continue;
                 }
 
+                if (networkVariableBaseTypeDef == null && netcodeTypeDef.Name == nameof(NetworkVariableBase))
+                {
+                    networkVariableBaseTypeDef = netcodeTypeDef;
+                    continue;
+                }
+
                 if (networkHandlerDelegateTypeDef == null && netcodeTypeDef.Name == nameof(NetworkManager.RpcReceiveHandler))
                 {
                     networkHandlerDelegateTypeDef = netcodeTypeDef;
@@ -548,6 +572,9 @@ private bool ImportReferences(ModuleDefinition moduleDefinition)
                     case k_NetworkBehaviour_endSendClientRpc:
                         m_NetworkBehaviour_endSendClientRpc_MethodRef = moduleDefinition.ImportReference(methodDef);
                         break;
+                    case k_NetworkBehaviour___nameNetworkVariable:
+                        m_NetworkBehaviour___nameNetworkVariable_MethodRef = moduleDefinition.ImportReference(methodDef);
+                        break;
                 }
             }
 
@@ -558,6 +585,21 @@ private bool ImportReferences(ModuleDefinition moduleDefinition)
                     case k_NetworkBehaviour_rpc_exec_stage:
                         m_NetworkBehaviour_rpc_exec_stage_FieldRef = moduleDefinition.ImportReference(fieldDef);
                         break;
+                    case k_NetworkBehaviour_NetworkVariableFields:
+                        m_NetworkBehaviour_NetworkVariableFields_FieldRef = moduleDefinition.ImportReference(fieldDef);
+                        break;
+                }
+            }
+
+
+            m_NetworkVariableBase_TypeRef = moduleDefinition.ImportReference(networkVariableBaseTypeDef);
+            foreach (var methodDef in networkVariableBaseTypeDef.Methods)
+            {
+                switch (methodDef.Name)
+                {
+                    case k_NetworkVariableBase_Initialize:
+                        m_NetworkVariableBase_Initialize_MethodRef = moduleDefinition.ImportReference(methodDef);
+                        break;
                 }
             }
 
@@ -785,6 +827,16 @@ private bool ImportReferences(ModuleDefinition moduleDefinition)
                 }
             }
 
+            // Standard types are really hard to reliably find using the Mono Cecil way, they resolve differently in Mono vs .NET Core
+            // Importing with typeof() is less dangerous for standard framework types though, so we can just do it
+            var exceptionType = typeof(Exception);
+            var exceptionCtor = exceptionType.GetConstructor(new[] { typeof(string) });
+            m_ExceptionCtorMethodReference = m_MainModule.ImportReference(exceptionCtor);
+
+            var listType = typeof(List<NetworkVariableBase>);
+            var addMethod = listType.GetMethod(nameof(List<NetworkVariableBase>.Add), new[] { typeof(NetworkVariableBase) });
+            m_List_NetworkVariableBase_Add = moduleDefinition.ImportReference(addMethod);
+
             return true;
         }
 
@@ -931,6 +983,8 @@ private void ProcessNetworkBehaviour(TypeDefinition typeDefinition, string[] ass
                 }
             }
 
+            GenerateVariableInitialization(typeDefinition);
+
             if (!typeDefinition.HasGenericParameters && !typeDefinition.IsGenericInstance)
             {
                 var fieldTypes = new List<TypeReference>();
@@ -1889,6 +1943,132 @@ private void InjectWriteAndCallBlocks(MethodDefinition methodDefinition, CustomA
             instructions.ForEach(instruction => processor.Body.Instructions.Insert(0, instruction));
         }
 
+        private void GenerateVariableInitialization(TypeDefinition type)
+        {
+            foreach (var methodDefinition in type.Methods)
+            {
+                if (methodDefinition.Name == k_NetworkBehaviour___initializeVariables)
+                {
+                    // If this hits, we've already generated the method for this class because a child class got processed first.
+                    return;
+                }
+            }
+
+            var method = new MethodDefinition(
+                k_NetworkBehaviour___initializeVariables,
+                MethodAttributes.Family | MethodAttributes.Virtual | MethodAttributes.HideBySig,
+                m_MainModule.TypeSystem.Void);
+
+            var processor = method.Body.GetILProcessor();
+
+            method.Body.Variables.Add(new VariableDefinition(m_MainModule.TypeSystem.Boolean));
+
+            processor.Emit(OpCodes.Nop);
+
+            foreach (var fieldDefinition in type.Fields)
+            {
+                FieldReference field = fieldDefinition;
+                if (type.HasGenericParameters)
+                {
+                    var genericType = new GenericInstanceType(fieldDefinition.DeclaringType);
+                    foreach (var parameter in fieldDefinition.DeclaringType.GenericParameters)
+                    {
+                        genericType.GenericArguments.Add(parameter);
+                    }
+                    field = new FieldReference(fieldDefinition.Name, fieldDefinition.FieldType, genericType);
+                }
+                if (field.FieldType.IsSubclassOf(m_NetworkVariableBase_TypeRef))
+                {
+                    // if({variable} != null) {
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Ldfld, field);
+                    processor.Emit(OpCodes.Ldnull);
+                    processor.Emit(OpCodes.Ceq);
+                    processor.Emit(OpCodes.Stloc_0);
+                    processor.Emit(OpCodes.Ldloc_0);
+
+                    var afterThrowInstruction = processor.Create(OpCodes.Nop);
+
+                    processor.Emit(OpCodes.Brfalse, afterThrowInstruction);
+
+                    // throw new Exception("...");
+                    processor.Emit(OpCodes.Nop);
+                    processor.Emit(OpCodes.Ldstr, $"{type.Name}.{field.Name} cannot be null. All {nameof(NetworkVariableBase)} instances must be initialized.");
+                    processor.Emit(OpCodes.Newobj, m_ExceptionCtorMethodReference);
+                    processor.Emit(OpCodes.Throw);
+
+                    // }
+                    processor.Append(afterThrowInstruction);
+
+                    // {variable}.Initialize(this);
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Ldfld, field);
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Callvirt, m_NetworkVariableBase_Initialize_MethodRef);
+
+                    // __nameNetworkVariable({variable}, "{variable}");
+                    processor.Emit(OpCodes.Nop);
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Ldfld, field);
+                    processor.Emit(OpCodes.Ldstr, field.Name.Replace("<", string.Empty).Replace(">k__BackingField", string.Empty));
+                    processor.Emit(OpCodes.Call, m_NetworkBehaviour___nameNetworkVariable_MethodRef);
+
+                    // NetworkVariableFields.Add({variable});
+                    processor.Emit(OpCodes.Nop);
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Ldfld, m_NetworkBehaviour_NetworkVariableFields_FieldRef);
+                    processor.Emit(OpCodes.Ldarg_0);
+                    processor.Emit(OpCodes.Ldfld, field);
+                    processor.Emit(OpCodes.Callvirt, m_List_NetworkVariableBase_Add);
+                }
+            }
+
+            // Find the base method...
+            MethodReference initializeVariablesBaseReference = null;
+            foreach (var methodDefinition in type.BaseType.Resolve().Methods)
+            {
+                if (methodDefinition.Name == k_NetworkBehaviour___initializeVariables)
+                {
+                    initializeVariablesBaseReference = m_MainModule.ImportReference(methodDefinition);
+                    break;
+                }
+            }
+
+            if (initializeVariablesBaseReference == null)
+            {
+                // If we couldn't find it, we have to go ahead and add it.
+                // The base class could be in another assembly... that's ok, this won't
+                // actually save but it'll generate the same method the same way later,
+                // so this at least allows us to reference it.
+                GenerateVariableInitialization(type.BaseType.Resolve());
+                foreach (var methodDefinition in type.BaseType.Resolve().Methods)
+                {
+                    if (methodDefinition.Name == k_NetworkBehaviour___initializeVariables)
+                    {
+                        initializeVariablesBaseReference = m_MainModule.ImportReference(methodDefinition);
+                        break;
+                    }
+                }
+            }
+
+            if (type.BaseType.Resolve().HasGenericParameters)
+            {
+                var baseTypeInstance = (GenericInstanceType)type.BaseType;
+                initializeVariablesBaseReference = initializeVariablesBaseReference.MakeGeneric(baseTypeInstance.GenericArguments.ToArray());
+            }
+
+            // base.__initializeVariables();
+            processor.Emit(OpCodes.Nop);
+            processor.Emit(OpCodes.Ldarg_0);
+            processor.Emit(OpCodes.Call, initializeVariablesBaseReference);
+            processor.Emit(OpCodes.Nop);
+
+            processor.Emit(OpCodes.Ret);
+
+            type.Methods.Add(method);
+        }
+
         private MethodDefinition GenerateStaticHandler(MethodDefinition methodDefinition, CustomAttribute rpcAttribute, uint rpcMethodId)
         {
             var typeSystem = methodDefinition.Module.TypeSystem;

com.unity.netcode.gameobjects/Editor/CodeGen/RuntimeAccessModifiersILPP.cs

@@ -112,7 +112,7 @@ private void ProcessNetworkBehaviour(TypeDefinition typeDefinition)
 
             foreach (var fieldDefinition in typeDefinition.Fields)
             {
-                if (fieldDefinition.Name == nameof(NetworkBehaviour.__rpc_exec_stage))
+                if (fieldDefinition.Name == nameof(NetworkBehaviour.__rpc_exec_stage) || fieldDefinition.Name == nameof(NetworkBehaviour.NetworkVariableFields))
                 {
                     fieldDefinition.IsFamily = true;
                 }
@@ -123,7 +123,7 @@ private void ProcessNetworkBehaviour(TypeDefinition typeDefinition)
                 if (methodDefinition.Name == nameof(NetworkBehaviour.__beginSendServerRpc) ||
                     methodDefinition.Name == nameof(NetworkBehaviour.__endSendServerRpc) ||
                     methodDefinition.Name == nameof(NetworkBehaviour.__beginSendClientRpc) ||
-                    methodDefinition.Name == nameof(NetworkBehaviour.__endSendClientRpc))
+                    methodDefinition.Name == nameof(NetworkBehaviour.__endSendClientRpc) || methodDefinition.Name == nameof(NetworkBehaviour.__initializeVariables) || methodDefinition.Name == nameof(NetworkBehaviour.__nameNetworkVariable))
                 {
                     methodDefinition.IsFamily = true;
                 }