Moved BufferManager to handles again.

aster/include/aster/CMakeLists.txt

@@ -3,6 +3,7 @@
 cmake_minimum_required(VERSION 3.13)
 
 add_subdirectory("core")
+add_subdirectory("systems")
 add_subdirectory("util")
 
 target_sources(aster_core 

aster/include/aster/systems/buffer_manager.h

@@ -11,11 +11,14 @@
 
 namespace systems
 {
+
+using BufferHandle = Handle<Buffer>;
+
 class BufferManager final : public Manager<Buffer>
 {
   public:
     BufferManager(const Device *device, const u32 maxCount);
 
-    Ref CreateStorageBuffer(usize size, cstr name = nullptr);
+    Handle CreateStorageBuffer(usize size, cstr name = nullptr);
 };
 } // namespace systems

aster/include/aster/systems/manager.h

@@ -7,55 +7,53 @@
 
 #include "aster/aster.h"
 
-#include <EASTL/intrusive_ptr.h>
-
 struct Device;
 
+
 template <typename T>
-    requires std::is_default_constructible_v<T>
+concept IsDeviceDestructible = requires(T a, Device *p) {
+    { a.Destroy(p) } -> std::convertible_to<void>;
+};
+
+template <typename T>
+    requires IsDeviceDestructible<T>
+class Handle;
+
+template <typename T>
+    requires std::is_default_constructible_v<T> && IsDeviceDestructible<T>
 class Manager
 {
-    using InternalType = T;
+    friend Handle<T>;
 
   public:
-    struct Type : InternalType
+    using Type = T;
+    using Handle = Handle<Type>;
+    static_assert(sizeof(Handle) == sizeof(u32));
+
+    static Manager *
+    Instance()
     {
-        void
-        AddRef()
-        {
-            m_Instance->AddRef(this);
-        }
+        assert(m_Instance);
 
-        void
-        Release()
-        {
-            m_Instance->Release(this);
-        }
-
-        u32
-        GetIndex()
-        {
-            return m_Instance->GetIndex(this);
-        }
-    };
-    static_assert(sizeof(Type) == sizeof(InternalType));
-
-    using Ref = eastl::intrusive_ptr<Type>;
-
-    static Manager *Instance();
+        return m_Instance;
+    }
 
     explicit Manager(const Device *device, const u32 maxCount)
         : m_MaxCount{maxCount}
         , m_FreeHead{0}
         , m_Device{device}
     {
+        assert(!m_Instance);
+
         m_Data = new Type[m_MaxCount];
-        m_RefCount = new u32[m_MaxCount];
+        m_RefCount = new std::atomic<u32>[m_MaxCount];
 
         for (u32 i = 0; i < m_MaxCount; ++i)
         {
-            m_RefCount[i] = (i + 1);
+            *Recast<u32 *>(&m_Data[i]) = (i + 1);
         }
+
+        m_Instance = this;
     }
 
     virtual ~Manager()
@@ -79,69 +77,219 @@ class Manager
 
     PIN_MEMORY(Manager);
 
-    void
-    AddRef(Type *p)
-    {
-        auto index = GetIndex(p);
-
-        ++m_RefCount[index];
-    }
-
-    void
-    Release(Type *p)
-    {
-        assert(p->IsValid());
-
-        auto index = GetIndex(p);
-
-        auto rc = --m_RefCount[index];
-
-        // Overflow case.
-        assert(rc != MaxValue<u32>);
-        if (rc == 0)
-        {
-            p->Destroy(m_Device);
-
-            m_RefCount[index] = m_FreeHead;
-            m_FreeHead = index;
-        }
-    }
-
-    u32
-    GetIndex(Type *p)
-    {
-        auto index = p - m_Data;
-        assert(index >= 0 && index < m_MaxCount);
-
-        return Cast<u32>(index);
-    }
-
   private:
-    Type *m_Data = nullptr;
-    u32 *m_RefCount = nullptr;
+    Type *m_Data = nullptr; // Data also keeps the freelist during 'not use'.
+    std::atomic<u32> *m_RefCount = nullptr;
     u32 m_MaxCount = 0;
     u32 m_FreeHead = 0;
 
     static Manager *m_Instance;
 
+    void
+    AddRef(const u32 index)
+    {
+        assert(index < m_MaxCount);
+        ++m_RefCount[index];
+    }
+
+    void
+    Release(const u32 index)
+    {
+        assert(index < m_MaxCount);
+        const u32 rc = --m_RefCount[index];
+        assert(rc != MaxValue<u32>);
+        if (rc == 0)
+        {
+            m_Data[index].Destroy(m_Device);
+        }
+    }
+
+    Type *
+    Fetch(const u32 index)
+    {
+        assert(index < m_MaxCount);
+        return &m_Data[index];
+    }
+
   protected:
     const Device *m_Device;
 
-    void
-    SetInstance(Manager *instance)
-    {
-        assert(!m_Instance);
-        m_Instance = instance;
-    }
-
-    Ref
+    std::pair<Handle, Type *>
     Alloc()
     {
         ERROR_IF(m_FreeHead >= m_MaxCount, "Max buffers allocated.") THEN_ABORT(-1);
 
         const auto index = m_FreeHead;
-        m_FreeHead = m_RefCount[index];
-        m_RefCount[index] = 0;
-        return Ref{&m_Data[index]};
+        Type *pAlloc = &m_Data[index];
+        m_FreeHead = *Recast<u32 *>(pAlloc);
+        return {Handle{index}, pAlloc};
+    }
+};
+
+template <typename T>
+    requires IsDeviceDestructible<T>
+class Ref
+{
+  public:
+    using Type = T;
+    using Handle = Handle<Type>;
+    using Manager = Manager<Type>;
+
+  protected:
+    Handle m_Handle;
+    Type *m_Pointer = nullptr;
+
+    friend Handle;
+
+    void
+    InitPtr()
+    {
+        m_Pointer = m_Handle.Fetch();
+    }
+
+  public:
+    Type *
+    Get()
+    {
+        assert(m_Pointer);
+        return m_Pointer;
+    }
+
+    const Type *
+    Get() const
+    {
+        assert(m_Pointer);
+        return m_Pointer;
+    }
+
+    Type *
+    operator->()
+    {
+        return Get();
+    }
+
+    const Type *
+    operator->() const
+    {
+        return Get();
+    }
+
+    Type &
+    operator*()
+    {
+        return *Get();
+    }
+
+    const Type &
+    operator*() const
+    {
+        return Get();
+    }
+
+    // The only constructor requires a valid construction.
+    explicit Ref(Handle &&handle)
+        : m_Handle{handle}
+    {
+        InitPtr();
+    }
+
+    // The only constructor requires a valid construction.
+    explicit Ref(const Handle &&handle)
+        : m_Handle{handle}
+    {
+        InitPtr();
+    }
+
+    Ref(const Ref &other) = default;
+    Ref(Ref &&other) noexcept = default;
+    Ref &operator=(const Ref &other) = default;
+    Ref &operator=(Ref &&other) noexcept = default;
+    ~Ref() = default;
+};
+
+template <typename T>
+    requires IsDeviceDestructible<T>
+class Handle
+{
+  public:
+    using Type = T;
+    using Manager = Manager<Type>;
+
+  protected:
+    constexpr static u32 INVALID_HANDLE = MaxValue<u32>;
+    u32 m_Internal = INVALID_HANDLE;
+
+    // The only constructor requires a valid construction.
+    explicit Handle(const u32 index)
+        : m_Internal{index}
+    {
+        AddRef();
+    }
+
+    friend Manager;
+    friend Ref<T>;
+
+  public:
+    Handle(const Handle &other)
+        : m_Internal(other.m_Internal)
+    {
+        AddRef();
+    }
+
+    Handle(Handle &&other) noexcept
+    {
+        std::swap(this->m_Internal, other.m_Internal);
+    }
+
+    Handle &
+    operator=(const Handle &other)
+    {
+        if (this == &other)
+            return *this;
+        m_Internal = other.m_Internal;
+        AddRef();
+        return *this;
+    }
+
+    Handle &
+    operator=(Handle &&other) noexcept
+    {
+        if (this == &other)
+            return *this;
+        std::swap(m_Internal, other.m_Internal);
+        return *this;
+    }
+
+    ~Handle()
+    {
+        if (m_Internal != INVALID_HANDLE)
+        {
+            Release();
+        }
+    }
+
+    Ref<T>
+    ToPointer()
+    {
+        return Ref{std::move(*this)};   
+    }
+
+  protected:
+    void
+    AddRef()
+    {
+        Manager::Instance()->AddRef(m_Internal);
+    }
+
+    void
+    Release()
+    {
+        Manager::Instance()->Release(m_Internal);
+    }
+
+    Type *
+    Fetch()
+    {
+        return Manager::Instance()->Fetch(m_Internal);
     }
 };