ArenaAllocator.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "uLang/Common/Memory/Allocator.h"
#include "uLang/Common/Templates/Storage.h"
 
#define UE_API ULANGCORE_API
 
namespace uLang
{
 
class CArenaAllocator : public CAllocatorInstance
{
public:
 
    UE_API CArenaAllocator(uint32_t ArenaSize);
    UE_API ~CArenaAllocator();
 
    UE_API void   Merge(CArenaAllocator && Other);
 
    void * Allocate(uint32_t NumBytes);
    UE_API void   DeallocateAll();
 
protected:
 
    enum { Alignment = 8 }; 
 
    static UE_API void * Allocate(const CAllocatorInstance * This, size_t NumBytes);
    static UE_API void * Reallocate(const CAllocatorInstance * This, void * Memory, size_t NumBytes);
    static UE_API void   Deallocate(const CAllocatorInstance * This, void * Memory);
 
    // Get more memory
    UE_API void AllocateNewArena();
 
    struct SArenaHeader
    {
        SArenaHeader * _Next;
    };
 
    SArenaHeader *  _First;        
    const uint32_t  _ArenaSize;    
    uint32_t        _BytesLeftInFirstArena; 
 
#if ULANG_DO_CHECK
    uint32_t        _NumAllocations;
    bool            _MatchDeallocations;
    uint32_t        _NumArenas;
    uint32_t        _BytesAllocatedTotal;
#endif
};
 
//=======================================================================================
// CArenaAllocator Inline Methods
//=======================================================================================
 
ULANG_FORCEINLINE void * CArenaAllocator::Allocate(uint32_t NumBytes)
{
    NumBytes = AlignUp(NumBytes, Alignment);
 
#if ULANG_DO_CHECK
    ULANG_ASSERTF(NumBytes <= _ArenaSize, "Must not allocate a memory block larger than the arena size!");
#endif
 
    if (NumBytes > _BytesLeftInFirstArena)
    {
        AllocateNewArena();
    }
 
    uint8_t * Memory = ((uint8_t *)(_First + 1)) + (_ArenaSize - _BytesLeftInFirstArena);
    _BytesLeftInFirstArena -= NumBytes;
 
#if ULANG_DO_CHECK
    ++_NumAllocations;
    _BytesAllocatedTotal += NumBytes;
#endif
 
    return Memory;
}
 
}
 
#undef UE_API