EM_Task/CoreUObject/Private/UObject/UObjectAllocator.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

/*=============================================================================
        UnObjAllocator.cpp: Unreal object allocation
=============================================================================*/

#include "UObject/UObjectAllocator.h"
#include "UObject/UObjectGlobals.h"

DEFINE_LOG_CATEGORY_STATIC(LogUObjectAllocator, Log, All);

/** Global UObjectBase allocator							*/
COREUOBJECT_API FUObjectAllocator GUObjectAllocator;

/**
 * Allocates and initializes the permanent object pool
 *
 * @param InPermanentObjectPoolSize size of permanent object pool
 */
void FUObjectAllocator::AllocatePermanentObjectPool(int32 InPermanentObjectPoolSize)
{
    PermanentObjectPoolSize         = InPermanentObjectPoolSize;
    PermanentObjectPool             = (uint8*)FMemory::MallocPersistentAuxiliary(PermanentObjectPoolSize);
    PermanentObjectPoolTail         = PermanentObjectPool;
    PermanentObjectPoolExceededTail = PermanentObjectPoolTail;
}

/**
 * Prints a debugf message to allow tuning
 */
void FUObjectAllocator::BootMessage()
{
    if (PermanentObjectPoolSize && PermanentObjectPoolExceededTail - PermanentObjectPool > PermanentObjectPoolSize)
    {
        UE_LOG(LogUObjectAllocator, Warning, TEXT("%i Exceeds size of permanent object pool %i, please tune SizeOfPermanentObjectPool."), PermanentObjectPoolExceededTail - PermanentObjectPool, PermanentObjectPoolSize);
    }
    else
    {
        UE_LOG(LogUObjectAllocator, Log, TEXT("%i out of %i bytes used by permanent object pool."), PermanentObjectPoolExceededTail - PermanentObjectPool, PermanentObjectPoolSize);
    }
}

/**
 * Allocates a UObjectBase from the free store or the permanent object pool
 *
 * @param Size size of uobject to allocate
 * @param Alignment alignment of uobject to allocate
 * @param bAllowPermanent if true, allow allocation in the permanent object pool, if it fits
 * @return newly allocated UObjectBase (not really a UObjectBase yet, no constructor like thing has been called).
 */
UObjectBase* FUObjectAllocator::AllocateUObject(int32 Size, int32 Alignment, bool bAllowPermanent)
{
    // Force alignment to 16 bytes
    Alignment               = 16;
    int32 AlignedSize       = Align(Size, Alignment);
    UObjectBase* Result     = NULL;

    const bool bPlaceInPerm = bAllowPermanent && (Align(PermanentObjectPoolTail, Alignment) + Size) <= (PermanentObjectPool + PermanentObjectPoolSize);
    if (bAllowPermanent && !bPlaceInPerm)
    {
        // advance anyway so we can determine how much space we should set aside in the ini
        uint8* AlignedPtr               = Align(PermanentObjectPoolExceededTail, Alignment);
        PermanentObjectPoolExceededTail = AlignedPtr + Size;
    }
    // Use object memory pool for objects disregarded by GC (initially loaded ones). This allows identifying their
    // GC status by simply looking at their address.
    if (bPlaceInPerm)
    {
        // Align current tail pointer and use it for object.
        uint8* AlignedPtr = Align(PermanentObjectPoolTail, Alignment);
        // Update tail pointer.
        PermanentObjectPoolTail = AlignedPtr + Size;
        Result                  = (UObjectBase*)AlignedPtr;
        if (PermanentObjectPoolExceededTail < PermanentObjectPoolTail)
        {
            PermanentObjectPoolExceededTail = PermanentObjectPoolTail;
        }
    }
    else
    {
        // Allocate new memory of the appropriate size and alignment.
        Result = (UObjectBase*)FMemory::DebugMalloc(AlignedSize);
    }
    return Result;
}

/**
 * Returns a UObjectBase to the free store, unless it is in the permanent object pool
 *
 * @param Object object to free
 */
void FUObjectAllocator::FreeUObject(UObjectBase* Object) const
{
    check(Object);
    // Only free memory if it was allocated directly from allocator and not from permanent object pool.
    if (ResidesInPermanentPool(Object) == false)
    {
        FMemory::DebugFree(Object);
    }
    // We only destroy objects residing in permanent object pool during the exit purge.
    else
    {
        check(GExitPurge);
    }
}