feat: Native container serialization (#2375)

Author: ShadauxCat

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -10,6 +10,7 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 ### Added
 
+- Added support for serializing `NativeArray<>` and `NativeList<>` in `FastBufferReader`/`FastBufferWriter`, `BufferSerializer`, `NetworkVariable`, and RPCs. (#2375)
 - The location of the automatically-created default network prefab list can now be configured (#2544)
 - Added: Message size limits (max single message and max fragmented message) can now be set using NetworkManager.SetMaxSingleMessageSize() and NetworkManager.SetMaxFragmentedMessageSize() for transports that don't work with the default values (#2530)
 - Added `NetworkObject.SpawnWithObservers` property (default is true) that when set to false will spawn a `NetworkObject` with no observers and will not be spawned on any client until `NetworkObject.NetworkShow` is invoked. (#2568)

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

@@ -123,7 +123,10 @@ 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.__initializeVariables) || methodDefinition.Name == nameof(NetworkBehaviour.__nameNetworkVariable))
+                    methodDefinition.Name == nameof(NetworkBehaviour.__endSendClientRpc) ||
+                    methodDefinition.Name == nameof(NetworkBehaviour.__initializeVariables) ||
+                    methodDefinition.Name == nameof(NetworkBehaviour.__nameNetworkVariable) ||
+                    methodDefinition.Name == nameof(NetworkBehaviour.__createNativeList))
                 {
                     methodDefinition.IsFamily = true;
                 }

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

@@ -275,6 +275,14 @@ internal void __endSendClientRpc(ref FastBufferWriter bufferWriter, uint rpcMeth
 #endif
         }
 
+#pragma warning disable IDE1006 // disable naming rule violation check
+        // RuntimeAccessModifiersILPP will make this `protected`
+        internal static NativeList<T> __createNativeList<T>() where T : unmanaged
+#pragma warning restore IDE1006 // restore naming rule violation check
+        {
+            return new NativeList<T>(Allocator.Temp);
+        }
+
         internal string GenerateObserverErrorMessage(ClientRpcParams clientRpcParams, ulong targetClientId)
         {
             var containerNameHoldingId = clientRpcParams.Send.TargetClientIds != null ? nameof(ClientRpcParams.Send.TargetClientIds) : nameof(ClientRpcParams.Send.TargetClientIdsNativeArray);

com.unity.netcode.gameobjects/Runtime/Core/NetworkBehaviour.cs

@@ -33,6 +33,13 @@ public NetworkVariable(T value = default,
             : base(readPerm, writePerm)
         {
             m_InternalValue = value;
+            // Since we start with IsDirty = true, this doesn't need to be duplicated
+            // right away. It won't get read until after ResetDirty() is called, and
+            // the duplicate will be made there. Avoiding calling
+            // NetworkVariableSerialization<T>.Duplicate() is important because calling
+            // it in the constructor might not give users enough time to set the
+            // DuplicateValue callback if they're using UserNetworkVariableSerialization
+            m_PreviousValue = default;
         }
 
         /// <summary>
@@ -41,6 +48,11 @@ public NetworkVariable(T value = default,
         [SerializeField]
         private protected T m_InternalValue;
 
+        private protected T m_PreviousValue;
+
+        private bool m_HasPreviousValue;
+        private bool m_IsDisposed;
+
         /// <summary>
         /// The value of the NetworkVariable container
         /// </summary>
@@ -61,9 +73,83 @@ public virtual T Value
                 }
 
                 Set(value);
+                m_IsDisposed = false;
             }
         }
 
+        internal ref T RefValue()
+        {
+            return ref m_InternalValue;
+        }
+
+        public override void Dispose()
+        {
+            if (m_IsDisposed)
+            {
+                return;
+            }
+
+            m_IsDisposed = true;
+            if (m_InternalValue is IDisposable internalValueDisposable)
+            {
+                internalValueDisposable.Dispose();
+            }
+
+            m_InternalValue = default;
+            if (m_HasPreviousValue && m_PreviousValue is IDisposable previousValueDisposable)
+            {
+                m_HasPreviousValue = false;
+                previousValueDisposable.Dispose();
+            }
+
+            m_PreviousValue = default;
+        }
+
+        ~NetworkVariable()
+        {
+            Dispose();
+        }
+
+        /// <summary>
+        /// Gets Whether or not the container is dirty
+        /// </summary>
+        /// <returns>Whether or not the container is dirty</returns>
+        public override bool IsDirty()
+        {
+            // For most cases we can use the dirty flag.
+            // This doesn't work for cases where we're wrapping more complex types
+            // like INetworkSerializable, NativeList, NativeArray, etc.
+            // Changes to the values in those types don't call the Value.set method,
+            // so we can't catch those changes and need to compare the current value
+            // against the previous one.
+            if (base.IsDirty())
+            {
+                return true;
+            }
+
+            // Cache the dirty value so we don't perform this again if we already know we're dirty
+            // Unfortunately we can't cache the NOT dirty state, because that might change
+            // in between to checks... but the DIRTY state won't change until ResetDirty()
+            // is called.
+            var dirty = !NetworkVariableSerialization<T>.AreEqual(ref m_PreviousValue, ref m_InternalValue);
+            SetDirty(dirty);
+            return dirty;
+        }
+
+        /// <summary>
+        /// Resets the dirty state and marks the variable as synced / clean
+        /// </summary>
+        public override void ResetDirty()
+        {
+            base.ResetDirty();
+            // Resetting the dirty value declares that the current value is not dirty
+            // Therefore, we set the m_PreviousValue field to a duplicate of the current
+            // field, so that our next dirty check is made against the current "not dirty"
+            // value.
+            m_HasPreviousValue = true;
+            NetworkVariableSerialization<T>.Serializer.Duplicate(m_InternalValue, ref m_PreviousValue);
+        }
+
         /// <summary>
         /// Sets the <see cref="Value"/>, marks the <see cref="NetworkVariable{T}"/> dirty, and invokes the <see cref="OnValueChanged"/> callback
         /// if there are subscribers to that event.