source: trunk/essentials/dev-lang/perl/win32/vmem.h@ 3296

/* vmem.h
 *
 * (c) 1999 Microsoft Corporation. All rights reserved. 
 * Portions (c) 1999 ActiveState Tool Corp, http://www.ActiveState.com/
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 * Options:
 *
 * Defining _USE_MSVCRT_MEM_ALLOC will cause all memory allocations
 * to be forwarded to MSVCRT.DLL. Defining _USE_LINKED_LIST as well will
 * track all allocations in a doubly linked list, so that the host can
 * free all memory allocated when it goes away.
 * If _USE_MSVCRT_MEM_ALLOC is not defined then Knuth's boundary tag algorithm
 * is used; defining _USE_BUDDY_BLOCKS will use Knuth's algorithm R
 * (Buddy system reservation)
 *
 */

#ifndef ___VMEM_H_INC___
#define ___VMEM_H_INC___

#define _USE_MSVCRT_MEM_ALLOC
#define _USE_LINKED_LIST

// #define _USE_BUDDY_BLOCKS

// #define _DEBUG_MEM
#ifdef _DEBUG_MEM
#define ASSERT(f) if(!(f)) DebugBreak();

inline void MEMODS(char *str)
{
    OutputDebugString(str);
    OutputDebugString("\n");
}

inline void MEMODSlx(char *str, long x)
{
    char szBuffer[512]; 
    sprintf(szBuffer, "%s %lx\n", str, x);
    OutputDebugString(szBuffer);
}

#define WALKHEAP() WalkHeap(0)
#define WALKHEAPTRACE() WalkHeap(1)

#else

#define ASSERT(f)
#define MEMODS(x)
#define MEMODSlx(x, y)
#define WALKHEAP()
#define WALKHEAPTRACE()

#endif

#ifdef _USE_MSVCRT_MEM_ALLOC

#ifndef _USE_LINKED_LIST
// #define _USE_LINKED_LIST
#endif

/* 
 * Pass all memory requests throught to msvcrt.dll 
 * optionaly track by using a doubly linked header
 */

typedef void (*LPFREE)(void *block);
typedef void* (*LPMALLOC)(size_t size);
typedef void* (*LPREALLOC)(void *block, size_t size);
#ifdef _USE_LINKED_LIST
class VMem;
typedef struct _MemoryBlockHeader* PMEMORY_BLOCK_HEADER;
typedef struct _MemoryBlockHeader {
    PMEMORY_BLOCK_HEADER    pNext;
    PMEMORY_BLOCK_HEADER    pPrev;
    VMem *owner;
} MEMORY_BLOCK_HEADER, *PMEMORY_BLOCK_HEADER;
#endif

class VMem
{
public:
    VMem();
    ~VMem();
    virtual void* Malloc(size_t size);
    virtual void* Realloc(void* pMem, size_t size);
    virtual void Free(void* pMem);
    virtual void GetLock(void);
    virtual void FreeLock(void);
    virtual int IsLocked(void);
    virtual long Release(void);
    virtual long AddRef(void);

    inline BOOL CreateOk(void)
    {
        return TRUE;
    };

protected:
#ifdef _USE_LINKED_LIST
    void LinkBlock(PMEMORY_BLOCK_HEADER ptr)
    {
        PMEMORY_BLOCK_HEADER next = m_Dummy.pNext;
        m_Dummy.pNext = ptr;
        ptr->pPrev = &m_Dummy;
        ptr->pNext = next;
        ptr->owner = this;
        next->pPrev = ptr;
    }
    void UnlinkBlock(PMEMORY_BLOCK_HEADER ptr)
    {
        PMEMORY_BLOCK_HEADER next = ptr->pNext;
        PMEMORY_BLOCK_HEADER prev = ptr->pPrev;
        prev->pNext = next;
        next->pPrev = prev;
    }

    MEMORY_BLOCK_HEADER m_Dummy;
#endif

    long                m_lRefCount;    // number of current users
    CRITICAL_SECTION    m_cs;           // access lock
    HINSTANCE           m_hLib;
    LPFREE              m_pfree;
    LPMALLOC            m_pmalloc;
    LPREALLOC           m_prealloc;
};

VMem::VMem()
{
    m_lRefCount = 1;
    InitializeCriticalSection(&m_cs);
#ifdef _USE_LINKED_LIST
    m_Dummy.pNext = m_Dummy.pPrev =  &m_Dummy;
    m_Dummy.owner = this;
#endif
    m_hLib = LoadLibrary("msvcrt.dll");
    if (m_hLib) {
        m_pfree = (LPFREE)GetProcAddress(m_hLib, "free");
        m_pmalloc = (LPMALLOC)GetProcAddress(m_hLib, "malloc");
        m_prealloc = (LPREALLOC)GetProcAddress(m_hLib, "realloc");
    }
}

VMem::~VMem(void)
{
#ifdef _USE_LINKED_LIST
    while (m_Dummy.pNext != &m_Dummy) {
        Free(m_Dummy.pNext+1);
    }
#endif
    if (m_hLib)
        FreeLibrary(m_hLib);
    DeleteCriticalSection(&m_cs);
}

void* VMem::Malloc(size_t size)
{
#ifdef _USE_LINKED_LIST
    GetLock();
    PMEMORY_BLOCK_HEADER ptr = (PMEMORY_BLOCK_HEADER)m_pmalloc(size+sizeof(MEMORY_BLOCK_HEADER));
    LinkBlock(ptr);
    FreeLock();
    return (ptr+1);
#else
    return m_pmalloc(size);
#endif
}

void* VMem::Realloc(void* pMem, size_t size)
{
#ifdef _USE_LINKED_LIST
    if (!pMem)
        return Malloc(size);

    if (!size) {
        Free(pMem);
        return NULL;
    }

    GetLock();
    PMEMORY_BLOCK_HEADER ptr = (PMEMORY_BLOCK_HEADER)(((char*)pMem)-sizeof(MEMORY_BLOCK_HEADER));
    UnlinkBlock(ptr);
    ptr = (PMEMORY_BLOCK_HEADER)m_prealloc(ptr, size+sizeof(MEMORY_BLOCK_HEADER));
    LinkBlock(ptr);
    FreeLock();

    return (ptr+1);
#else
    return m_prealloc(pMem, size);
#endif
}

void VMem::Free(void* pMem)
{
#ifdef _USE_LINKED_LIST
    if (pMem) {
        PMEMORY_BLOCK_HEADER ptr = (PMEMORY_BLOCK_HEADER)(((char*)pMem)-sizeof(MEMORY_BLOCK_HEADER));
        if (ptr->owner != this) {
            if (ptr->owner) {
#if 1
                dTHX;
                int *nowhere = NULL;
                Perl_warn(aTHX_ "Free to wrong pool %p not %p",this,ptr->owner);
                *nowhere = 0;
#else
                ptr->owner->Free(pMem); 
#endif
            }
            return;
        }
        GetLock();
        UnlinkBlock(ptr);
        ptr->owner = NULL;
        m_pfree(ptr);
        FreeLock();
    }
#else
    m_pfree(pMem);
#endif
}

void VMem::GetLock(void)
{
    EnterCriticalSection(&m_cs);
}

void VMem::FreeLock(void)
{
    LeaveCriticalSection(&m_cs);
}

int VMem::IsLocked(void)
{
#if 0
    /* XXX TryEnterCriticalSection() is not available in some versions
     * of Windows 95.  Since this code is not used anywhere yet, we 
     * skirt the issue for now. */
    BOOL bAccessed = TryEnterCriticalSection(&m_cs);
    if(bAccessed) {
        LeaveCriticalSection(&m_cs);
    }
    return !bAccessed;
#else
    ASSERT(0);  /* alarm bells for when somebody calls this */
    return 0;
#endif
}

long VMem::Release(void)
{
    long lCount = InterlockedDecrement(&m_lRefCount);
    if(!lCount)
        delete this;
    return lCount;
}

long VMem::AddRef(void)
{
    long lCount = InterlockedIncrement(&m_lRefCount);
    return lCount;
}

#else   /* _USE_MSVCRT_MEM_ALLOC */

/*
 * Knuth's boundary tag algorithm Vol #1, Page 440.
 *
 * Each block in the heap has tag words before and after it,
 *  TAG
 *  block
 *  TAG
 * The size is stored in these tags as a long word, and includes the 8 bytes
 * of overhead that the boundary tags consume.  Blocks are allocated on long
 * word boundaries, so the size is always multiples of long words.  When the
 * block is allocated, bit 0, (the tag bit), of the size is set to 1.  When 
 * a block is freed, it is merged with adjacent free blocks, and the tag bit
 * is set to 0.
 *
 * A linked list is used to manage the free list. The first two long words of
 * the block contain double links.  These links are only valid when the block
 * is freed, therefore space needs to be reserved for them.  Thus, the minimum
 * block size (not counting the tags) is 8 bytes.
 *
 * Since memory allocation may occur on a single threaded, explict locks are not
 * provided.
 * 
 */

const long lAllocStart = 0x00020000; /* start at 128K */
const long minBlockSize = sizeof(void*)*2;
const long sizeofTag = sizeof(long);
const long blockOverhead = sizeofTag*2;
const long minAllocSize = minBlockSize+blockOverhead;
#ifdef _USE_BUDDY_BLOCKS
const long lSmallBlockSize = 1024;
const size_t nListEntries = ((lSmallBlockSize-minAllocSize)/sizeof(long));

inline size_t CalcEntry(size_t size)
{
    ASSERT((size&(sizeof(long)-1)) == 0);
    return ((size - minAllocSize) / sizeof(long));
}
#endif

typedef BYTE* PBLOCK;   /* pointer to a memory block */

/*
 * Macros for accessing hidden fields in a memory block:
 *
 * SIZE     size of this block (tag bit 0 is 1 if block is allocated)
 * PSIZE    size of previous physical block
 */

#define SIZE(block)     (*(ULONG*)(((PBLOCK)(block))-sizeofTag))
#define PSIZE(block)    (*(ULONG*)(((PBLOCK)(block))-(blockOverhead)))
inline void SetTags(PBLOCK block, long size)
{
    SIZE(block) = size;
    PSIZE(block+(size&~1)) = size;
}

/*
 * Free list pointers
 * PREV pointer to previous block
 * NEXT pointer to next block
 */

#define PREV(block)     (*(PBLOCK*)(block))
#define NEXT(block)     (*(PBLOCK*)((block)+sizeof(PBLOCK)))
inline void SetLink(PBLOCK block, PBLOCK prev, PBLOCK next)
{
    PREV(block) = prev;
    NEXT(block) = next;
}
inline void Unlink(PBLOCK p)
{
    PBLOCK next = NEXT(p);
    PBLOCK prev = PREV(p);
    NEXT(prev) = next;
    PREV(next) = prev;
}
#ifndef _USE_BUDDY_BLOCKS
inline void AddToFreeList(PBLOCK block, PBLOCK pInList)
{
    PBLOCK next = NEXT(pInList);
    NEXT(pInList) = block;
    SetLink(block, pInList, next);
    PREV(next) = block;
}
#endif

/* Macro for rounding up to the next sizeof(long) */
#define ROUND_UP(n)     (((ULONG)(n)+sizeof(long)-1)&~(sizeof(long)-1))
#define ROUND_UP64K(n)  (((ULONG)(n)+0x10000-1)&~(0x10000-1))
#define ROUND_DOWN(n)   ((ULONG)(n)&~(sizeof(long)-1))

/*
 * HeapRec - a list of all non-contiguous heap areas
 *
 * Each record in this array contains information about a non-contiguous heap area.
 */

const int maxHeaps = 32; /* 64 was overkill */
const long lAllocMax   = 0x80000000; /* max size of allocation */

#ifdef _USE_BUDDY_BLOCKS
typedef struct _FreeListEntry
{
    BYTE    Dummy[minAllocSize];        // dummy free block
} FREE_LIST_ENTRY, *PFREE_LIST_ENTRY;
#endif

#ifndef _USE_BUDDY_BLOCKS
#define USE_BIGBLOCK_ALLOC
#endif
/*
 * performance tuning
 * Use VirtualAlloc() for blocks bigger than nMaxHeapAllocSize since
 * Windows 95/98/Me have heap managers that are designed for memory 
 * blocks smaller than four megabytes.
 */

#ifdef USE_BIGBLOCK_ALLOC
const int nMaxHeapAllocSize = (1024*512);  /* don't allocate anything larger than this from the heap */
#endif

typedef struct _HeapRec
{
    PBLOCK      base;   /* base of heap area */
    ULONG       len;    /* size of heap area */
#ifdef USE_BIGBLOCK_ALLOC
    BOOL        bBigBlock;  /* was allocate using VirtualAlloc */
#endif
} HeapRec;

class VMem
{
public:
    VMem();
    ~VMem();
    virtual void* Malloc(size_t size);