-some usefull functions for IDManager

-added EntityManager.removeEntity(EntityID)
-EntitiesBlock now has ID usefull for updating first_free_block in EntityInfo

source/ecs/id_manager.d

@@ -30,6 +30,19 @@ struct IDManager
         m_ids_array[entity.id.id].entity = &entity;
     }
 
+    Entity* getEntityPointer(EntityID id)
+    {
+        Data* data = &m_ids_array[id.id];
+        if(data.counter != id.counter)return null;
+        else return data.entity;
+    }
+
+    bool isExist(EntityID id)
+    {
+        Data* data = &m_ids_array[id.id];
+        return data.counter == id.counter;
+    }
+
     struct Data
     {
         uint counter = 0;
@@ -61,5 +74,7 @@ unittest
     assert(id1 == EntityID(1,2));
     assert(id2 == EntityID(0,2));
     assert(id3 == EntityID(2,1));
+    assert(manager.isExist(id3));
+    assert(!manager.isExist(EntityID(0,1)));
 
 }

source/ecs/manager.d

@@ -54,7 +54,7 @@ class EntityManager
             string ret;
             foreach (i, param; Parameters!(Sys.update))
             {
-                ret ~= "system.components[" ~ i.to!string
+                ret ~= "system.m_components[" ~ i.to!string
                     ~ "] = components_map.get(types[" ~ i.to!string ~ "].stringof);\n";
             }
             return ret;
@@ -66,7 +66,7 @@ class EntityManager
             {
                 static if (hasMember!(Sys, "update"))
                 {
-                    Sys* s = cast(Sys*) data.system.system_pointer;
+                    Sys* s = cast(Sys*) data.system.m_system_pointer;
 
                     EntitiesBlock* block = data.info.first_block;
                     while (block !is null)
@@ -83,7 +83,7 @@ class EntityManager
                 }
             }
 
-            system.update = &callUpdate;
+            system.m_update = &callUpdate;
         }
 
         static if (hasMember!(Sys, "onEnable"))
@@ -110,9 +110,9 @@ class EntityManager
             system.m_disable = &callDisable;
         }
 
-        system.system_pointer = cast(void*) Mallocator.instance.make!Sys;
+        system.m_system_pointer = cast(void*) Mallocator.instance.make!Sys;
 
-        system.components = Mallocator.instance.makeArray!uint(types.length);
+        system.m_components = Mallocator.instance.makeArray!uint(types.length);
         mixin(genCompList());
 
         systems.add(system);
@@ -142,7 +142,7 @@ class EntityManager
             foreach (data; info.callers)
             {
                 if (data.system.enabled)
-                    (cast(SytemFuncType) data.system.update)(data, null); //caller(call_data,null);
+                    (cast(SytemFuncType) data.system.m_update)(data, null); //caller(call_data,null);
             }
         }
     }
@@ -176,7 +176,7 @@ class EntityManager
 
             foreach (ref system; systems)
             {
-                if (system.update is null)
+                if (system.m_update is null)
                     continue;
                 addEntityCaller(*info, system);
             }
@@ -193,9 +193,9 @@ class EntityManager
     void addEntityCaller(ref EntityInfo entity, ref System system)
     {
         CallData call_data = CallData(&system, &entity, null);
-        ushort[] deltas = (cast(ushort*) alloca(system.components.length * ushort.sizeof))[0
+        ushort[] deltas = (cast(ushort*) alloca(system.m_components.length * ushort.sizeof))[0
-            .. system.components.length];
+            .. system.m_components.length];
-        foreach (i, id; system.components)
+        foreach (i, id; system.m_components)
         {
             deltas[i] = ushort.max;
             foreach (i2, id2; entity.components)
@@ -214,7 +214,7 @@ class EntityManager
         }
         if (deltas)
         {
-            call_data.deltas = Mallocator.instance.makeArray(deltas); //Mallocator.instance.makeArray!ushort(system.components.length);
+            call_data.deltas = Mallocator.instance.makeArray(deltas); //Mallocator.instance.makeArray!ushort(system.m_components.length);
             entity.callers.add(call_data);
         }
     }
@@ -225,7 +225,7 @@ class EntityManager
         Mallocator.instance.dispose(template_);
     }
 
-    void addEntity(EntityTemplate* tmpl)
+    ref Entity addEntity(EntityTemplate* tmpl)
     {
         EntitiesBlock* previous_block;
         EntitiesBlock* block = tmpl.info.first_with_free_space; //tmpl.info.first_block;
@@ -241,10 +241,12 @@ class EntityManager
                 if (previous_block is null)
                 {
                     tmpl.info.first_block = block;
+                    block.id = 0;
                 }
                 else
                 {
                     previous_block.next_block = block;
+                    block.id = previous_block.id + 1;
                 }
                 tmpl.info.first_with_free_space = block;
                 break; // new block certainly has free space
@@ -267,6 +269,37 @@ class EntityManager
         entity.id = id_manager.getNewID();
         entity.updateID();
         block.entities_count++;
+        return *entity;
+    }
+
+    void removeEntity(EntityID id)
+    {
+        Entity* entity = id_manager.getEntityPointer(id);
+        if(entity is null)return;
+        EntitiesBlock* block = getMetaData(entity);
+        id_manager.releaseID(id);
+        
+        void* data_begin = block.dataBegin();
+        uint pos = cast(int)(cast(void*)entity - data_begin) / block.type_data.size;
+
+        block.entities_count--;
+
+        if(block.type_data.first_with_free_space.id > block.id)block.type_data.first_with_free_space = block;
+
+        if(pos == block.entities_count)return;
+
+        void* src = data_begin + block.entities_count * block.type_data.size;
+        void* dst = data_begin + pos * block.type_data.size;
+
+        memcpy(dst,src,block.type_data.size);
+
+        entity = cast(Entity*) dst;
+        entity.updateID();
+    }
+
+    EntitiesBlock* getMetaData(void* pointer)
+    {
+        return cast(EntitiesBlock*)(cast(size_t) pointer & (~cast(size_t)(page_size - 1)));
     }
 
     struct ComponentInfo
@@ -304,6 +337,7 @@ class EntityManager
 
         EntityInfo* type_data;
         uint entities_count;
+        uint id;
         EntitiesBlock* next_block;
         ///there is a loooot of data (4kB, pure magic)
     }
@@ -317,7 +351,9 @@ class EntityManager
 
     alias SytemFuncType = void function(ref EntityManager.CallData data, void* entity);
 
+    ///Single page size. Must be power of two.
     enum page_size = 4096;
+    ///Number of pages in block.
     enum pages_in_block = 128;
 
     IDManager id_manager;

source/ecs/system.d

@@ -5,15 +5,6 @@ import ecs.manager;
 
 struct System
 {
-    ///should system update and catch events?
-    bool m_enabled = false;
-    ///system priority
-    int prority;
-    ///pointer to system implementation
-    void* system_pointer;
-
-    uint[] components;
-
     bool enabled()
     {
         return m_enabled;
@@ -21,18 +12,34 @@ struct System
 
     void enable()
     {
-        if(!m_enabled && m_enable)m_enable(system_pointer);
+        if(!m_enabled && m_enable)m_enable(m_system_pointer);
         m_enabled = true;
     }
 
     void disable()
     {
-        if(m_enabled && m_disable)m_disable(system_pointer);
+        if(m_enabled && m_disable)m_disable(m_system_pointer);
         m_enabled = false;
     }
 
+    int priority()
+    {
+        return m_priority;
+    }
+
+package:
+
+    ///should system update and catch events?
+    bool m_enabled = false;
+    ///system priority
+    int m_priority;
+    ///pointer to system implementation
+    void* m_system_pointer;
+
+    uint[] m_components;
+
     //void function(ref EntityManager.CallData data, void* entity) update;
-    void* update; ///workaroud for DMD bug with upper line
+    void* m_update; ///workaroud for DMD bug with upper line
 
     void function(void* system_pointer) m_enable;
     void function(void* system_pointer) m_disable;

tests/tests.d

@@ -135,7 +135,33 @@ int main()
 
 	time = MonoTime.currTime;
 
-	foreach(i; 0..1_000_000)gEM.addEntity(tmpl);
+	//foreach(i; 0..1_000_000)gEM.addEntity(tmpl);
+
+	//foreach(i; 0..1_000_000)gEM.removeEntity(gEM.addEntity(tmpl).id);
+
+	EntityID[1000] idss;
+
+	foreach(i; 0..1_000)
+	{
+		foreach(j; 0..1_000)idss[j] = gEM.addEntity(tmpl).id;
+		foreach(j; 0..1_000)gEM.removeEntity(idss[j]);
+	}
+
+	uint blocks = 0;
+	foreach(info; &gEM.entities_infos.byValue)
+	{
+		EntityManager.EntitiesBlock* block = info.first_block;
+		while(block !is null)
+		{
+			block = block.next_block;
+			blocks++;
+		}
+	}
+	writeln("Entities blocks: ",blocks);
+
+	/*Entity entity = gEM.addEntity(tmpl);
+	gEM.removeEntity(entity.id);
+	gEM.addEntity(tmpl);*/
 
 	dur = (MonoTime.currTime - time).total!"usecs";
 	writeln("Entities adding: ",dur," usecs");