Engine - ECS: removed TreeNode.arrayHeap

Engine/src/ECS/Archetype/EntityStore.cs

@@ -77,7 +77,9 @@ public abstract partial class EntityStoreBase
     // --- nodes
     [Browse(Never)] internal            int                     entityCount;        //  4   - number of all entities
     // --- misc
-    [Browse(Never)] private   readonly  ArchetypeKey            searchKey;          //  8   - key buffer to find archetypes by key
+    [Browse(Never)] private  readonly   ArchetypeKey            searchKey;          //  8   - key buffer to find archetypes by key
+    [Browse(Never)] private  readonly   int[]                   singleIds;      //   8
+    [Browse(Never)] private             int                     singleIndex;    //   4
 
                     private             InternBase              internBase;         // 40
     /// <summary>Contains state of <see cref="EntityStoreBase"/> not relevant for application development.</summary>
@@ -135,13 +137,22 @@ protected EntityStoreBase()
         internBase.entityBatches        = new StackArray<EntityBatch>       (Array.Empty<EntityBatch>());
         internBase.createEntityBatches  = new StackArray<CreateEntityBatch> (Array.Empty<CreateEntityBatch>());
         internBase.entityLists          = new StackArray<EntityList>        (Array.Empty<EntityList>());
+        singleIds                       = new int[SingleMax];
     }
-
-    protected internal abstract void    UpdateEntityCompIndex(int id, int compIndex);
-
     #endregion
 
+    private const int SingleMax = 32;
 
+    /// safe alternative for unsafe variant using <see cref="System.Runtime.InteropServices.MemoryMarshal.CreateReadOnlySpan{T}"/>.
+    internal ReadOnlySpan<int> GetSpanId(int id) {
+        var ids     = singleIds;
+        var index   = singleIndex;
+        singleIndex = (index + 1) % SingleMax;
+        ids[index]  = id;
+        return new ReadOnlySpan<int>(ids, index, 1);
+    }
+
+    protected internal abstract void    UpdateEntityCompIndex(int id, int compIndex);
 
 #region exceptions
     /// <summary>

Engine/src/ECS/Collections/Entities.cs

@@ -5,7 +5,6 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Runtime.InteropServices;
 using System.Text;
 using static System.Diagnostics.DebuggerBrowsableState;
 using Browse = System.Diagnostics.DebuggerBrowsableAttribute;
@@ -15,21 +14,21 @@
 namespace Friflo.Engine.ECS;
 
 [DebuggerTypeProxy(typeof(EntitiesDebugView))]
-public struct Entities : IReadOnlyList<Entity>
+public readonly struct Entities : IReadOnlyList<Entity>
 {
 #region properties
     public              int                 Count       => count;
     public              EntityStore         EntityStore => store;
-    public              ReadOnlySpan<int>   Ids         => ids != null ? new ReadOnlySpan<int>(ids, start, count) : MemoryMarshal.CreateReadOnlySpan(ref id, 1);
+    public              ReadOnlySpan<int>   Ids         => ids != null ? new ReadOnlySpan<int>(ids, start, count) : store.GetSpanId(start);
     public   override   string              ToString()  => $"Entity[{count}]";
     #endregion
 
 #region interal fields
     internal readonly   int[]           ids;    //  8
     internal readonly   EntityStore     store;  //  8
+    /// id - if <see cref="ids"/> == null.
     internal readonly   int             start;  //  4
     internal readonly   int             count;  //  4
-    internal            int             id;     //  4
     #endregion
 
 #region general
@@ -47,7 +46,7 @@ internal Entities(EntityStore store) {
 
     internal Entities(EntityStore store, int id) {
         this.store  = store;
-        this.id     = id;
+        start       = id;
         count       = 1;
     }
 
@@ -58,7 +57,7 @@ public Entity this[int index] {
             }
             // case: count == 1
             if (index != 0) throw new IndexOutOfRangeException();
-            return new Entity(store, id);
+            return new Entity(store, start);
         }
     }
 
@@ -106,7 +105,7 @@ internal EntityEnumerator(in Entities entities) {
         store   = entities.store;
         start   = entities.start - 1;
         last    = start + entities.count;
-        id      = entities.id;
+        id      = entities.start;
         index   = start;
     }
 

Engine/src/ECS/Collections/EntityList.cs

@@ -144,7 +144,7 @@ private void AddEntityTree(Entity entity)
     {
         AddInternal(entity.Id);
         entity.TryGetTreeNode(out var node);
-        foreach (var id in node.ChildIds) {
+        foreach (var id in node.GetChildIds(entityStore)) {
             var child = new Entity(entityStore, id);
             AddEntityTree(child);
         }

Engine/src/ECS/Collections/IdArray/IdArray.cs

@@ -42,7 +42,7 @@ private string GetString()
 
 internal static class IdArrayExtensions {
 
-    public static ReadOnlySpan<int> GetIdSpan(this ref IdArray array, IdArrayHeap heap)
+    internal static ReadOnlySpan<int> GetIdSpan(this ref IdArray array, IdArrayHeap heap)
     {
         var count = array.count;
         switch (count) {

Engine/src/ECS/Components/TreeNode.cs

@@ -2,10 +2,7 @@
 // See LICENSE file in the project root for full license information.
 
 using System;
-using System.Runtime.InteropServices;
 using Friflo.Engine.ECS.Collections;
-using static System.Diagnostics.DebuggerBrowsableState;
-using Browse = System.Diagnostics.DebuggerBrowsableAttribute;
 
 // ReSharper disable once CheckNamespace
 namespace Friflo.Engine.ECS;
@@ -14,27 +11,22 @@ namespace Friflo.Engine.ECS;
 [ComponentKey(null)]
 public struct TreeNode : IComponent    // todo should be internal
 {
-    public                      ReadOnlySpan<int>   ChildIds    => GetChildIds();
     public                      int                 ChildCount  => childIds.count;
     public          override    string              ToString()  => $"ChildCount: {childIds.count}";
 
 //  [Browse(Never)] internal    int         parentId;   //  4   0 if entity has no parent
                     internal    IdArray     childIds;   //  8
-                    internal    IdArrayHeap arrayHeap;  //  8
-
-    internal TreeNode(IdArrayHeap arrayHeap) {
-        this.arrayHeap = arrayHeap;
-    }
+                    internal    int[]       dummy;      //  8  todo remove
 
     /// same as <see cref="IdArrayExtensions.GetIdSpan"/>
-    private ReadOnlySpan<int>  GetChildIds()
+    public ReadOnlySpan<int>  GetChildIds(EntityStore store)
     {
         var count = childIds.count;
         switch (count) {
-            case 0:     return default;
-            case 1:     return MemoryMarshal.CreateReadOnlySpan(ref childIds.start, 1);
+            case 0: return default;
+            case 1: return store.GetSpanId(childIds.start);
         }
         var curPoolIndex = IdArrayHeap.PoolIndex(count);
-        return new ReadOnlySpan<int>(arrayHeap.GetPool(curPoolIndex).Ids, childIds.start, count);
+        return new ReadOnlySpan<int>(store.extension.hierarchyHeap.GetPool(curPoolIndex).Ids, childIds.start, count);
     }
 }

Engine/src/ECS/Entity/ChildEntities.cs

@@ -23,7 +23,7 @@ public struct ChildEntities : IEnumerable<Entity>
 {
     // --- public properties
                         public              int                 Count           => node.childIds.count;
-                        public              ReadOnlySpan<int>   Ids             => node.ChildIds;
+                        public              ReadOnlySpan<int>   Ids             => node.GetChildIds(store);
 
                         public              Entity              this[int index] => new Entity(store, Ids[index]);
                         public override     string              ToString()      => $"Entity[{Count}]";
@@ -79,7 +79,7 @@ internal ChildEnumerator(in ChildEntities childEntities) {
     }
 
     // --- IEnumerator<>
-    public readonly Entity Current   => new Entity(store, node.childIds.Get(index - 1, node.arrayHeap));
+    public readonly Entity Current   => new Entity(store, node.childIds.Get(index - 1, store.extension.hierarchyHeap));
 
     // --- IEnumerator
     public bool MoveNext() {

Engine/src/ECS/Entity/Store/NodeTree.cs

@@ -62,9 +62,7 @@ private ref TreeNode GetTreeNodeRef(Entity entity)
             entity.AddComponent<TreeNode>(); // set entity.archetype
             heap = entity.archetype.heapMap[StructInfo<TreeNode>.Index];
         } 
-        ref var node = ref ((StructHeap<TreeNode>)heap).components[entity.compIndex];
-        node.arrayHeap = extension.hierarchyHeap;
-        return ref node;
+        return ref ((StructHeap<TreeNode>)heap).components[entity.compIndex];
     }
 
     internal int AddChild (int parentId, int childId)
@@ -98,7 +96,7 @@ internal int AddChild (int parentId, int childId)
         int index           = parent.childIds.count;
     //  childNode.parentId  = parentId;
         extension.parentMap[childId]  = parentId;
-        parent.childIds.AddId(childId, parent.arrayHeap);
+        parent.childIds.AddId(childId, extension.hierarchyHeap);
         SetTreeFlags(localNodes, childId, nodes[parentId].flags & NodeFlags.TreeNode);
 
         OnChildNodeAdd(parentId, childId, index);
@@ -187,7 +185,7 @@ internal Entity GetChildEntityByIndex(int parentId, int childIndex) {
     internal static int GetChildIndex(Entity parent, int childId)
     {
         parent.TryGetTreeNode(out var node);
-        var childIds    = node.ChildIds;
+        var childIds    = node.GetChildIds(parent.store);
         int count       = node.childIds.count;
         for (int n = 0; n < count; n++) {
             if (childId != childIds[n]) {
@@ -202,21 +200,21 @@ private int RemoveChildNode (int parentId, int childId)
     {
         var parent          = new Entity(this, parentId);
         ref var treeNode    = ref GetTreeNodeRef(parent);
-        var childIds        = treeNode.ChildIds;
+        var childIds        = treeNode.GetChildIds(this);
         int count           = treeNode.childIds.count;
         for (int n = 0; n < count; n++) {
             if (childId != childIds[n]) {
                 continue;
             }
-            treeNode.childIds.RemoveAt(n, treeNode.arrayHeap, keepOrder: true);
+            treeNode.childIds.RemoveAt(n, extension.hierarchyHeap, keepOrder: true);
             return n;
         }
         throw new InvalidOperationException($"unexpected state: child id not found. parent id: {parentId}, child id: {childId}");
     }
 
-    private static void InsertChildNode (ref TreeNode parent, int childId, int childIndex)
+    private void InsertChildNode (ref TreeNode parent, int childId, int childIndex)
     {
-        parent.childIds.InsertAt(childIndex, childId, parent.arrayHeap);
+        parent.childIds.InsertAt(childIndex, childId, extension.hierarchyHeap);
     }
 
     /*
@@ -244,13 +242,13 @@ private void SetChildNodes(Entity parent, ReadOnlySpan<int> newChildIds)
             return;
         }
     //  ref var node        = ref nodes[parent.Id];
-        var     newCount    = newChildIds.Length;
+
         /* if (!parent.HasTreeNode()) {    // todo could optimize
             parent.AddComponent(new TreeNode(extension.hierarchyHeap));
         } */
         ref var node = ref GetTreeNodeRef(parent);
-        node.childIds.SetArray(newChildIds, node.arrayHeap);
-        SetChildParents(node, newCount, parent.Id);
+        node.childIds.SetArray(newChildIds, extension.hierarchyHeap);
+        SetChildParents(node, parent.Id);
     }
 
     private void SetChildNodesWithEvents(Entity parent, ReadOnlySpan<int> newIds)
@@ -259,7 +257,6 @@ private void SetChildNodesWithEvents(Entity parent, ReadOnlySpan<int> newIds)
             parent.AddComponent(new TreeNode(extension.hierarchyHeap));
         } */
         ref var node    = ref GetTreeNodeRef(parent);
-        var newCount    = newIds.Length;
         // --- 1. Remove missing ids in new child ids.          E.g.    cur ids [2, 3, 4, 5]
         //                                                             *newIds  [6, 4, 2, 5]    => remove: 3
         //                                                              result  [2, 4, 5]
@@ -283,7 +280,7 @@ private void SetChildNodesWithEvents(Entity parent, ReadOnlySpan<int> newIds)
         ChildIds_RemoveRange(ref node, first, last, parent.Id);
         ChildIds_InsertRange(ref node, first, last, newIds, parent.Id);
 
-        SetChildParents     (    node, newCount, parent.Id);
+        SetChildParents     (    node, parent.Id);
     }
 
     // --- 1.
@@ -294,13 +291,13 @@ private void ChildIds_RemoveMissingIds(ReadOnlySpan<int> newIds, ref TreeNode no
         foreach (var id in newIds) {
             newIdSet.Add(id);
         }
-        var childIds = node.ChildIds;
+        var childIds = node.GetChildIds(this);
         for (int index = node.childIds.count - 1; index >= 0; index--) {
             var id = childIds[index];
             if (newIdSet.Contains(id)) {
                 continue;
             }
-            node.childIds.RemoveAt(index, node.arrayHeap, keepOrder: true);
+            node.childIds.RemoveAt(index, extension.hierarchyHeap, keepOrder: true);
         //  nodes[id].parentId          = Static.NoParentId;
             extension.parentMap.Remove(id);
         //  OnChildNodeRemove(node.id, id, index);
@@ -313,7 +310,7 @@ private void ChildIds_InsertNewIds(ReadOnlySpan<int> newIds, ref TreeNode node,
     {
         var curIdSet = idBufferSet;
         curIdSet.Clear();
-        foreach (var id in node.ChildIds) {
+        foreach (var id in node.GetChildIds(this)) {
             curIdSet.Add(id);
         }
         var newCount = newIds.Length;
@@ -325,15 +322,15 @@ private void ChildIds_InsertNewIds(ReadOnlySpan<int> newIds, ref TreeNode node,
                 continue;
             }
             // case: child ids does not contain id      => insert at specified position
-            node.childIds.InsertAt(index, id, node.arrayHeap);
+            node.childIds.InsertAt(index, id, extension.hierarchyHeap);
             OnChildNodeAdd(parentId, id, index);
         }
     }
 
     // --- 3.1
-    private static void ChildIds_GetRange(in TreeNode node, ReadOnlySpan<int> newIds, out int first, out int last)
+    private void ChildIds_GetRange(in TreeNode node, ReadOnlySpan<int> newIds, out int first, out int last)
     {
-        var childIds = node.ChildIds;
+        var childIds = node.GetChildIds(this);
         var count = newIds.Length;
         first = 0;
         for (; first < count; first++) {
@@ -358,10 +355,11 @@ private static void ChildIds_GetRange(in TreeNode node, ReadOnlySpan<int> newIds
     // --- 3.2
     private void ChildIds_RemoveRange(ref TreeNode node, int first, int last, int parentId)
     {
+        var heap = extension.hierarchyHeap;
         for (int index = last; index >= first; index--)
         {
-            int removedId = node.childIds.Get(index, node.arrayHeap);
-            node.childIds.RemoveAt(index, node.arrayHeap, keepOrder: true);
+            int removedId = node.childIds.Get(index, heap);
+            node.childIds.RemoveAt(index, heap, keepOrder: true);
         //  nodes[removedId].parentId   = Static.NoParentId;
             extension.parentMap.Remove(removedId);
             OnChildNodeRemove(parentId, removedId, index);
@@ -374,16 +372,15 @@ private void ChildIds_InsertRange(ref TreeNode node, int first, int last, ReadOn
         for (int index = first; index <= last; index++)
         {
             var addedId = newIds[index];
-            node.childIds.InsertAt(index, addedId, node.arrayHeap);
+            node.childIds.InsertAt(index, addedId, extension.hierarchyHeap);
             OnChildNodeAdd(parentId, addedId, index);
         }
     }
 
-    // todo - remove redundant count
-    private void SetChildParents(in TreeNode node, int count, int parentId)
+    private void SetChildParents(in TreeNode node, int parentId)
     {
     //  var localNodes = nodes;
-        foreach (int childId in  node.ChildIds)
+        foreach (int childId in  node.GetChildIds(this))
         {
         //  ref var child   = ref localNodes[childId];
             extension.parentMap.TryGetValue(childId, out int curParentId);
@@ -681,6 +678,6 @@ internal static ReadOnlySpan<int> GetChildIds(Entity entity)
     //  ref var node = ref store.nodes[id];
     //  return new ReadOnlySpan<int>(node.childIds, 0, node.childCount);
         entity.TryGetTreeNode(out var node);
-        return node.ChildIds;
+        return node.GetChildIds(entity.store);
     }
 }

Engine/src/Tests-internal/ECS/Test_IdArray.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Diagnostics;
-using System.Runtime.InteropServices;
 using Friflo.Engine.ECS.Collections;
 using NUnit.Framework;
 using Tests.Utils;

Engine/src/Tests/ECS/Entity/Test_Entity_Tree.cs

@@ -86,7 +86,7 @@ public static void Test_AddChild()
         AreEqual(1,         childEntities.Ids.Length);
         var rootNode = root.GetComponent<TreeNode>();
         AreEqual(1,         rootNode.ChildCount);
-        AreEqual(1,         rootNode.ChildIds.Length);
+        AreEqual(1,         rootNode.GetChildIds(store).Length);
         AreEqual("ChildCount: 1", rootNode.ToString());
     //  AreEqual("id: 1  \"root\"  [EntityName]  ChildCount: 1  flags: Created",  root.ToString()); TREE_NODE
         AreEqual("id: 1  \"root\"  [EntityName, TreeNode]",  root.ToString());
@@ -140,7 +140,7 @@ public static void Test_InsertChild()
             AreEqual(1,                                 childNodes.Ids.Length);
             var rootNode = root.GetComponent<TreeNode>();
             AreEqual(1,                                 rootNode.ChildCount);
-            AreEqual(1,                                 rootNode.ChildIds.Length);
+            AreEqual(1,                                 rootNode.GetChildIds(store).Length);
             AreEqual("id: 1  \"root\"  [EntityName, TreeNode]",  root.ToString());
             IsTrue(child4 ==                            childNodes[0]);
             events.RemoveHandler();

Engine/src/Tests/ECS/Serialize/Test_ComponentReader.cs

@@ -457,7 +457,7 @@ public static void Test_ComponentReader_Load_DataEntity_UsePidAsId()
         var entity20    = store.GetEntityById(20);
         AreEqual(10,    store.GetInternalParentId(entity20.Id));
         AreEqual(20,    entity20.Pid);
-        var childIds = treeNode.ChildIds;
+        var childIds = treeNode.GetChildIds(store);
         for (int n = 0; n < 100; n++) {
             AreEqual(n + 20, childIds[n]);
         }
@@ -487,7 +487,7 @@ public static void Test_ComponentReader_Load_DataEntity_RandomPids() {
         var entity2     = store.GetEntityById(2);
         AreEqual(1,     store.GetInternalParentId(entity2.Id));
         AreEqual(20,    entity2.Pid);
-        var childIds = treeNode1.ChildIds;
+        var childIds = treeNode1.GetChildIds(store);
         for (int n = 0; n < 100; n++) {
             AreEqual(n + 2, childIds[n]);
         }