OVR_Allocator.h

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/************************************************************************************

PublicHeader:   OVR.h
Filename    :   OVR_Allocator.h
Content     :   Installable memory allocator
Created     :   September 19, 2012
Notes       : 

Copyright   :   Copyright 2012 Oculus VR, Inc. All Rights reserved.

Use of this software is subject to the terms of the Oculus license
agreement provided at the time of installation or download, or which
otherwise accompanies this software in either electronic or hard copy form.

************************************************************************************/

#ifndef OVR_Allocator_h
#define OVR_Allocator_h

#include "OVR_Types.h"

//-----------------------------------------------------------------------------------

// ***** Disable template-unfriendly MS VC++ warnings
#if defined(OVR_CC_MSVC)
// Pragma to prevent long name warnings in in VC++
#pragma warning(disable : 4503)
#pragma warning(disable : 4786)
// In MSVC 7.1, warning about placement new POD default initializer
#pragma warning(disable : 4345)
#endif

// Un-define new so that placement constructors work
#undef new


//-----------------------------------------------------------------------------------
// ***** Placement new overrides

// Calls constructor on own memory created with "new(ptr) type"
#ifndef __PLACEMENT_NEW_INLINE
#define __PLACEMENT_NEW_INLINE

#   if defined(OVR_CC_MWERKS) || defined(OVR_CC_BORLAND) || defined(OVR_CC_GNU)
#      include <new>
#   else
    // Useful on MSVC
    OVR_FORCE_INLINE void* operator new     (OVR::UPInt n, void *ptr) { OVR_UNUSED(n); return ptr; }
    OVR_FORCE_INLINE void  operator delete  (void *, void *)     { }
#   endif

#endif // __PLACEMENT_NEW_INLINE



//------------------------------------------------------------------------
// ***** Macros to redefine class new/delete operators

// Types specifically declared to allow disambiguation of address in
// class member operator new.

#define OVR_MEMORY_REDEFINE_NEW_IMPL(class_name, check_delete)                          \
    void*   operator new(UPInt sz)                                                      \
    { void *p = OVR_ALLOC_DEBUG(sz, __FILE__, __LINE__); return p; }                                              \
    void*   operator new(UPInt sz, const char* file, int line)                          \
    { void* p = OVR_ALLOC_DEBUG(sz, file, line); OVR_UNUSED2(file, line); return p; }   \
    void    operator delete(void *p)                                                    \
    { check_delete(class_name, p); OVR_FREE(p); }                                       \
    void    operator delete(void *p, const char*, int)                                  \
    { check_delete(class_name, p); OVR_FREE(p); }                          

#define OVR_MEMORY_DEFINE_PLACEMENT_NEW                                                 \
    void*   operator new        (UPInt n, void *ptr)    { OVR_UNUSED(n); return ptr; }  \
    void    operator delete     (void *ptr, void *ptr2) { OVR_UNUSED2(ptr,ptr2); }


#define OVR_MEMORY_CHECK_DELETE_NONE(class_name, p)

// Redefined all delete/new operators in a class without custom memory initialization
#define OVR_MEMORY_REDEFINE_NEW(class_name) \
    OVR_MEMORY_REDEFINE_NEW_IMPL(class_name, OVR_MEMORY_CHECK_DELETE_NONE)


namespace OVR {

//-----------------------------------------------------------------------------------
// ***** Construct / Destruct

// Construct/Destruct functions are useful when new is redefined, as they can
// be called instead of placement new constructors.


template <class T>
OVR_FORCE_INLINE T*  Construct(void *p)
{
    return ::new(p) T;
}

template <class T>
OVR_FORCE_INLINE T*  Construct(void *p, const T& source)
{
    return ::new(p) T(source);
}

// Same as above, but allows for a different type of constructor.
template <class T, class S>
OVR_FORCE_INLINE T*  ConstructAlt(void *p, const S& source)
{
    return ::new(p) T(source);
}

template <class T, class S1, class S2>
OVR_FORCE_INLINE T*  ConstructAlt(void *p, const S1& src1, const S2& src2)
{
    return ::new(p) T(src1, src2);
}

template <class T>
OVR_FORCE_INLINE void ConstructArray(void *p, UPInt count)
{
    UByte *pdata = (UByte*)p;
    for (UPInt i=0; i< count; ++i, pdata += sizeof(T))
    {
        Construct<T>(pdata);
    }
}

template <class T>
OVR_FORCE_INLINE void ConstructArray(void *p, UPInt count, const T& source)
{
    UByte *pdata = (UByte*)p;
    for (UPInt i=0; i< count; ++i, pdata += sizeof(T))
    {
        Construct<T>(pdata, source);
    }
}

template <class T>
OVR_FORCE_INLINE void Destruct(T *pobj)
{
    pobj->~T();
    OVR_UNUSED1(pobj); // Fix incorrect 'unused variable' MSVC warning.
}

template <class T>
OVR_FORCE_INLINE void DestructArray(T *pobj, UPInt count)
{   
    for (UPInt i=0; i<count; ++i, ++pobj)
        pobj->~T();
}


//-----------------------------------------------------------------------------------
// ***** Allocator

// Allocator defines a memory allocation interface that developers can override
// to to provide memory for OVR; an instance of this class is typically created on
// application startup and passed into System or OVR::System constructor.
// 
//
// Users implementing this interface must provide three functions: Alloc, Free,
// and Realloc. Implementations of these functions must honor the requested alignment.
// Although arbitrary alignment requests are possible, requested alignment will
// typically be small, such as 16 bytes or less.

class Allocator
{
    friend class System;
public:

    // *** Standard Alignment Alloc/Free

    // Allocate memory of specified size with default alignment.
    // Alloc of size==0 will allocate a tiny block & return a valid pointer;
    // this makes it suitable for new operator.
    virtual void*   Alloc(UPInt size) = 0;
    // Same as Alloc, but provides an option of passing debug data.
    virtual void*   AllocDebug(UPInt size, const char* file, unsigned line)
    { OVR_UNUSED2(file, line); return Alloc(size); }

    // Reallocate memory block to a new size, copying data if necessary. Returns the pointer to
    // new memory block, which may be the same as original pointer. Will return 0 if reallocation
    // failed, in which case previous memory is still valid.
    // Realloc to decrease size will never fail.
    // Realloc of pointer == 0 is equivalent to Alloc
    // Realloc to size == 0, shrinks to the minimal size, pointer remains valid and requires Free().
    virtual void*   Realloc(void* p, UPInt newSize) = 0;

    // Frees memory allocated by Alloc/Realloc.
    // Free of null pointer is valid and will do nothing.
    virtual void    Free(void *p) = 0;


    // *** Standard Alignment Alloc/Free

    // Allocate memory of specified alignment.
    // Memory allocated with AllocAligned MUST be freed with FreeAligned.
    // Default implementation will delegate to Alloc/Free after doing rounding.
    virtual void*   AllocAligned(UPInt size, UPInt align);    
    // Frees memory allocated with AllocAligned.
    virtual void    FreeAligned(void* p);
    
    // Returns the pointer to the current globally installed Allocator instance.
    // This pointer is used for most of the memory allocations.
    static Allocator* GetInstance() { return pInstance; }


protected:
    // onSystemShutdown is called on the allocator during System::Shutdown.
    // At this point, all allocations should've been freed.
    virtual void    onSystemShutdown() { }

public:
    static  void    setInstance(Allocator* palloc)    
    {
        OVR_ASSERT((pInstance == 0) || (palloc == 0));
        pInstance = palloc;
    }

private:

    static Allocator* pInstance;
};



//------------------------------------------------------------------------
// ***** Allocator_SingletonSupport

// Allocator_SingletonSupport is a Allocator wrapper class that implements
// the InitSystemSingleton static function, used to create a global singleton
// used for the OVR::System default argument initialization.
//
// End users implementing custom Allocator interface don't need to make use of this base
// class; they can just create an instance of their own class on stack and pass it to System.

template<class D>
class Allocator_SingletonSupport : public Allocator
{
    struct AllocContainer
    {        
        UPInt Data[(sizeof(D) + sizeof(UPInt)-1) / sizeof(UPInt)];
        bool  Initialized;
        AllocContainer() : Initialized(0) { }
    };

    AllocContainer* pContainer;

public:
    Allocator_SingletonSupport() : pContainer(0) { }

    // Creates a singleton instance of this Allocator class used
    // on OVR_DEFAULT_ALLOCATOR during System initialization.
    static  D*  InitSystemSingleton()
    {
        static AllocContainer Container;
        OVR_ASSERT(Container.Initialized == false);

        Allocator_SingletonSupport<D> *presult = Construct<D>((void*)Container.Data);
        presult->pContainer   = &Container;
        Container.Initialized = true;
        return (D*)presult;
    }

protected:
    virtual void onSystemShutdown()
    {
        Allocator::onSystemShutdown();
        if (pContainer)
        {
            pContainer->Initialized = false;
            Destruct((D*)this);
            pContainer = 0;
        }
    }
};

//------------------------------------------------------------------------
// ***** Default Allocator

// This allocator is created and used if no other allocator is installed.
// Default allocator delegates to system malloc.

class DefaultAllocator : public Allocator_SingletonSupport<DefaultAllocator>
{
public:
    virtual void*   Alloc(UPInt size);
    virtual void*   AllocDebug(UPInt size, const char* file, unsigned line);
    virtual void*   Realloc(void* p, UPInt newSize);
    virtual void    Free(void *p);
};


//------------------------------------------------------------------------
// ***** Memory Allocation Macros

// These macros should be used for global allocation. In the future, these
// macros will allows allocation to be extended with debug file/line information
// if necessary.

#define OVR_REALLOC(p,s)        OVR::Allocator::GetInstance()->Realloc((p),(s))
#define OVR_FREE(p)             OVR::Allocator::GetInstance()->Free((p))
#define OVR_ALLOC_ALIGNED(s,a)  OVR::Allocator::GetInstance()->AllocAligned((s),(a))
#define OVR_FREE_ALIGNED(p)     OVR::Allocator::GetInstance()->FreeAligned((p))

#ifdef OVR_BUILD_DEBUG
#define OVR_ALLOC(s)            OVR::Allocator::GetInstance()->AllocDebug((s), __FILE__, __LINE__)
#define OVR_ALLOC_DEBUG(s,f,l)  OVR::Allocator::GetInstance()->AllocDebug((s), f, l)
#else
#define OVR_ALLOC(s)            OVR::Allocator::GetInstance()->Alloc((s))
#define OVR_ALLOC_DEBUG(s,f,l)  OVR::Allocator::GetInstance()->Alloc((s))
#endif

//------------------------------------------------------------------------

// Base class that overrides the new and delete operators.
// Deriving from this class, even as a multiple base, incurs no space overhead.
class NewOverrideBase
{
public:

    // Redefine all new & delete operators.
    OVR_MEMORY_REDEFINE_NEW(NewOverrideBase)
};


} // OVR


// Redefine operator 'new' if necessary.
#if defined(OVR_DEFINE_NEW)
#define new OVR_DEFINE_NEW
#endif


#endif // OVR_Memory