intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 93 insertions, 0 deletions

diff --git a/util/memory/addstorage.h b/util/memory/addstorage.h
new file mode 100644
index 0000000000..597c73a988
--- /dev/null
+++ b/util/memory/addstorage.h
@@ -0,0 +1,93 @@
+#pragma once
+
+#include <util/system/align.h>
+#include <util/system/defaults.h>
+
+#include <new>
+
+namespace NPrivate {
+    class TAdditionalStorageInfo {
+    public:
+        constexpr TAdditionalStorageInfo(size_t length) noexcept
+            : Length_(length)
+        {
+        }
+
+        constexpr size_t Length() const noexcept {
+            return Length_;
+        }
+
+    private:
+        size_t Length_;
+    };
+}
+
+template <class T>
+class alignas(::NPrivate::TAdditionalStorageInfo) TAdditionalStorage {
+    using TInfo = ::NPrivate::TAdditionalStorageInfo;
+
+public:
+    inline TAdditionalStorage() noexcept = default;
+
+    inline ~TAdditionalStorage() = default;
+
+    inline void* operator new(size_t len1, size_t len2) {
+        static_assert(alignof(T) >= alignof(TInfo));
+        Y_ASSERT(len1 == sizeof(T));
+        void* data = ::operator new(CombinedSizeOfInstanceWithTInfo() + len2);
+        void* info = InfoPtr(static_cast<T*>(data));
+        Y_UNUSED(new (info) TInfo(len2));
+
+        return data;
+    }
+
+    inline void operator delete(void* ptr) noexcept {
+        DoDelete(ptr);
+    }
+
+    inline void operator delete(void* ptr, size_t) noexcept {
+        DoDelete(ptr);
+    }
+
+    inline void operator delete(void* ptr, size_t, size_t) noexcept {
+        /*
+         * this delete operator can be called automagically by compiler
+         */
+
+        DoDelete(ptr);
+    }
+
+    inline void* AdditionalData() const noexcept {
+        return (char*)(static_cast<const T*>(this)) + CombinedSizeOfInstanceWithTInfo();
+    }
+
+    static inline T* ObjectFromData(void* data) noexcept {
+        return reinterpret_cast<T*>(static_cast<char*>(data) - CombinedSizeOfInstanceWithTInfo());
+    }
+
+    inline size_t AdditionalDataLength() const noexcept {
+        return InfoPtr(static_cast<const T*>(this))->Length();
+    }
+
+private:
+    static inline void DoDelete(void* ptr) noexcept {
+        TInfo* info = InfoPtr(static_cast<T*>(ptr));
+        info->~TInfo();
+        ::operator delete(ptr);
+    }
+
+    static constexpr size_t CombinedSizeOfInstanceWithTInfo() noexcept {
+        return AlignUp(sizeof(T), alignof(TInfo)) + sizeof(TInfo);
+    }
+
+    static constexpr TInfo* InfoPtr(T* instance) noexcept {
+        return const_cast<TInfo*>(InfoPtr(static_cast<const T*>(instance)));
+    }
+
+    static constexpr const TInfo* InfoPtr(const T* instance) noexcept {
+        return reinterpret_cast<const TInfo*>(reinterpret_cast<const char*>(instance) + CombinedSizeOfInstanceWithTInfo() - sizeof(TInfo));
+    }
+
+private:
+    void* operator new(size_t) = delete;
+};