component updates at end of frame

encompass-cs/ComponentManager.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Encompass.Exceptions;
 
 namespace Encompass
 {
@@ -22,6 +23,8 @@ namespace Encompass
         private readonly HashSet<Guid> componentsMarkedForDeactivation = new HashSet<Guid>();
         private readonly HashSet<Guid> componentsMarkedForRemoval = new HashSet<Guid>();
 
+        private readonly Dictionary<Guid, IComponent> pendingUpdates = new Dictionary<Guid, IComponent>();
+
         //shared references with EntityManager
         private readonly HashSet<Guid> entitiesWithAddedComponents;
         private readonly HashSet<Guid> entitiesWithRemovedComponents;
@@ -149,9 +152,24 @@ namespace Encompass
             return componentIDToEntityID[componentID];
         }
 
-        internal void UpdateComponent<TComponent>(Guid componentID, TComponent newComponentValue) where TComponent : struct, IComponent
+        internal void AddUpdateComponentOperation<TComponent>(Guid componentID, TComponent newComponentValue) where TComponent : struct, IComponent
         {
-            IDToComponent[componentID] = newComponentValue;
+            if (pendingUpdates.ContainsKey(componentID))
+            {
+                throw new RepeatUpdateComponentException("Component with ID {0} was updated multiple times this frame", componentID);
+            }
+
+            pendingUpdates.Add(componentID, newComponentValue);
+        }
+
+        internal void PerformComponentUpdates()
+        {
+            foreach (var idPair in pendingUpdates)
+            {
+                IDToComponent[idPair.Key] = idPair.Value;
+            }
+
+            pendingUpdates.Clear();
         }
 
         internal void MarkAllComponentsOnEntityForRemoval(Guid entityID)

encompass-cs/Engine.cs

@@ -134,7 +134,7 @@ namespace Encompass
                 throw new IllegalWriteException("Engine {0} tried to write undeclared Component {1}", this.GetType().Name, typeof(TComponent).Name);
             }
 
-            componentManager.UpdateComponent(componentID, newComponent);
+            componentManager.AddUpdateComponentOperation(componentID, newComponent);
         }
 
         protected void UpdateComponent<TComponent>(Guid componentID, TComponent newComponentValue) where TComponent : struct, IComponent

encompass-cs/Exceptions/RepeatUpdateComponentException.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace Encompass.Exceptions
+{
+    public class RepeatUpdateComponentException : Exception
+    {
+        public RepeatUpdateComponentException(
+            string format,
+            params object[] args
+        ) : base(string.Format(format, args)) { }
+    }
+}

encompass-cs/World.cs

@@ -35,6 +35,7 @@ namespace Encompass
             messageManager.ClearMessages();
             entityManager.DestroyMarkedEntities();
 
+            componentManager.PerformComponentUpdates();
             componentManager.ActivateMarkedComponents();
             componentManager.DeactivateMarkedComponents();
             componentManager.RemoveMarkedComponents();

encompass-cs/WorldBuilder.cs

@@ -224,6 +224,7 @@ namespace Encompass
                 renderManager
             );
 
+            componentManager.PerformComponentUpdates();
             componentManager.ActivateMarkedComponents();
             componentManager.DeactivateMarkedComponents();
             componentManager.RemoveMarkedComponents();

test/EngineTest.cs

@@ -31,6 +31,7 @@ namespace Tests
             }
         }
 
+
         public class ReadComponentTestEngine : Engine
         {
             public override void Update(double dt)
@@ -126,16 +127,17 @@ namespace Tests
                 component.myInt = 420;
                 component.myString = "blaze it";
                 UpdateComponent(componentID, component);
+            }
+        }
 
-                resultComponent = ReadComponent<MockComponent>().Item2;
+        // this test needs to be improved...
-            }
-        }
 
         [Test]
         public void UpdateComponent()
         {
             var worldBuilder = new WorldBuilder();
             worldBuilder.AddEngine(new UpdateComponentTestEngine());
+            worldBuilder.AddEngine(new ReadComponentTestEngine());
 
             var entity = worldBuilder.CreateEntity();
 
@@ -147,7 +149,8 @@ namespace Tests
 
             var world = worldBuilder.Build();
 
-            world.Update(0.01f);
+            world.Update(0.01);
+            world.Update(0.01);
 
             Assert.AreEqual(420, resultComponent.myInt);
             Assert.AreEqual("blaze it", resultComponent.myString);
@@ -642,5 +645,48 @@ namespace Tests
             
             Assert.Throws<ComponentAndMessageWriteException>(() => worldBuilder.AddEngine(new EngineThatWritesComponentAndMessage()));
         }
+
+        struct MockComponentUpdateMessage : IMessage
+        {
+            public Guid componentID;
+            public MockComponent mockComponent;
+        }
+
+        [Reads(typeof(MockComponentUpdateMessage))]
+        [Writes(typeof(MockComponent))]
+        class RepeatUpdateEngine : Engine
+        {
+            public override void Update(double dt)
+            {
+                foreach (var mockComponentUpdateMessage in ReadMessages<MockComponentUpdateMessage>())
+                {
+                    UpdateComponent(mockComponentUpdateMessage.componentID, mockComponentUpdateMessage.mockComponent);
+                    UpdateComponent(mockComponentUpdateMessage.componentID, mockComponentUpdateMessage.mockComponent);
+                }
+            }
+        }
+
+        [Test]
+        public void EngineUpdatesComponentMultipleTimes()
+        {
+            var worldBuilder = new WorldBuilder();
+            worldBuilder.AddEngine(new RepeatUpdateEngine());
+
+            var entity = worldBuilder.CreateEntity();
+
+            MockComponent mockComponent;
+            mockComponent.myInt = 1;
+            mockComponent.myString = "5";
+
+            var mockComponentID = worldBuilder.AddComponent(entity, mockComponent);
+
+            MockComponentUpdateMessage mockComponentUpdateMessage;
+            mockComponentUpdateMessage.componentID = mockComponentID;
+            mockComponentUpdateMessage.mockComponent = mockComponent;
+            worldBuilder.EmitMessage(mockComponentUpdateMessage);
+
+            var world = worldBuilder.Build();
+            Assert.Throws<RepeatUpdateComponentException>(() => world.Update(0.01));
+        }
     }
 }