homework-jianmu/source/libs/tdb/src/db/tdbPage.c

595 lines
19 KiB
C

/*
* Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
*
* This program is free software: you can use, redistribute, and/or modify
* it under the terms of the GNU Affero General Public License, version 3
* or later ("AGPL"), as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "tdbInt.h"
extern SPageMethods pageMethods;
extern SPageMethods pageLargeMethods;
#define TDB_PAGE_HDR_SIZE(pPage) ((pPage)->pPageMethods->szPageHdr)
#define TDB_PAGE_FREE_CELL_SIZE(pPage) ((pPage)->pPageMethods->szFreeCell)
#define TDB_PAGE_NCELLS(pPage) (*(pPage)->pPageMethods->getCellNum)(pPage)
#define TDB_PAGE_CCELLS(pPage) (*(pPage)->pPageMethods->getCellBody)(pPage)
#define TDB_PAGE_FCELL(pPage) (*(pPage)->pPageMethods->getCellFree)(pPage)
#define TDB_PAGE_NFREE(pPage) (*(pPage)->pPageMethods->getFreeBytes)(pPage)
#define TDB_PAGE_CELL_OFFSET_AT(pPage, idx) (*(pPage)->pPageMethods->getCellOffset)(pPage, idx)
#define TDB_PAGE_NCELLS_SET(pPage, NCELLS) (*(pPage)->pPageMethods->setCellNum)(pPage, NCELLS)
#define TDB_PAGE_CCELLS_SET(pPage, CCELLS) (*(pPage)->pPageMethods->setCellBody)(pPage, CCELLS)
#define TDB_PAGE_FCELL_SET(pPage, FCELL) (*(pPage)->pPageMethods->setCellFree)(pPage, FCELL)
#define TDB_PAGE_NFREE_SET(pPage, NFREE) (*(pPage)->pPageMethods->setFreeBytes)(pPage, NFREE)
#define TDB_PAGE_CELL_OFFSET_AT_SET(pPage, idx, OFFSET) (*(pPage)->pPageMethods->setCellOffset)(pPage, idx, OFFSET)
#define TDB_PAGE_CELL_AT(pPage, idx) ((pPage)->pData + TDB_PAGE_CELL_OFFSET_AT(pPage, idx))
#define TDB_PAGE_MAX_FREE_BLOCK(pPage, szAmHdr) \
((pPage)->pageSize - (szAmHdr)-TDB_PAGE_HDR_SIZE(pPage) - sizeof(SPageFtr))
static int tdbPageAllocate(SPage *pPage, int size, SCell **ppCell);
static int tdbPageDefragment(SPage *pPage);
static int tdbPageFree(SPage *pPage, int idx, SCell *pCell, int szCell);
int tdbPageCreate(int pageSize, SPage **ppPage, void *(*xMalloc)(void *, size_t), void *arg) {
SPage *pPage;
u8 *ptr;
int size;
ASSERT(TDB_IS_PGSIZE_VLD(pageSize));
*ppPage = NULL;
size = pageSize + sizeof(*pPage);
if (xMalloc == NULL) {
xMalloc = tdbDefaultMalloc;
}
ptr = (u8 *)((*xMalloc)(arg, size));
if (ptr == NULL) {
return -1;
}
memset(ptr, 0, size);
pPage = (SPage *)(ptr + pageSize);
TDB_INIT_PAGE_LOCK(pPage);
pPage->pageSize = pageSize;
pPage->pData = ptr;
if (pageSize < 65536) {
pPage->pPageMethods = &pageMethods;
} else {
pPage->pPageMethods = &pageLargeMethods;
}
*ppPage = pPage;
return 0;
}
int tdbPageDestroy(SPage *pPage, void (*xFree)(void *arg, void *ptr), void *arg) {
u8 *ptr;
if (!xFree) {
xFree = tdbDefaultFree;
}
ptr = pPage->pData;
(*xFree)(arg, ptr);
return 0;
}
void tdbPageZero(SPage *pPage, u8 szAmHdr, int (*xCellSize)(const SPage *, SCell *)) {
pPage->pPageHdr = pPage->pData + szAmHdr;
TDB_PAGE_NCELLS_SET(pPage, 0);
TDB_PAGE_CCELLS_SET(pPage, pPage->pageSize - sizeof(SPageFtr));
TDB_PAGE_FCELL_SET(pPage, 0);
TDB_PAGE_NFREE_SET(pPage, TDB_PAGE_MAX_FREE_BLOCK(pPage, szAmHdr));
pPage->pCellIdx = pPage->pPageHdr + TDB_PAGE_HDR_SIZE(pPage);
pPage->pFreeStart = pPage->pCellIdx;
pPage->pFreeEnd = pPage->pData + TDB_PAGE_CCELLS(pPage);
pPage->pPageFtr = (SPageFtr *)(pPage->pData + pPage->pageSize - sizeof(SPageFtr));
pPage->nOverflow = 0;
pPage->xCellSize = xCellSize;
ASSERT((u8 *)pPage->pPageFtr == pPage->pFreeEnd);
}
void tdbPageInit(SPage *pPage, u8 szAmHdr, int (*xCellSize)(const SPage *, SCell *)) {
pPage->pPageHdr = pPage->pData + szAmHdr;
pPage->pCellIdx = pPage->pPageHdr + TDB_PAGE_HDR_SIZE(pPage);
pPage->pFreeStart = pPage->pCellIdx + TDB_PAGE_OFFSET_SIZE(pPage) * TDB_PAGE_NCELLS(pPage);
pPage->pFreeEnd = pPage->pData + TDB_PAGE_CCELLS(pPage);
pPage->pPageFtr = (SPageFtr *)(pPage->pData + pPage->pageSize - sizeof(SPageFtr));
pPage->nOverflow = 0;
pPage->xCellSize = xCellSize;
ASSERT(pPage->pFreeEnd >= pPage->pFreeStart);
ASSERT(pPage->pFreeEnd - pPage->pFreeStart <= TDB_PAGE_NFREE(pPage));
}
int tdbPageInsertCell(SPage *pPage, int idx, SCell *pCell, int szCell, u8 asOvfl) {
int nFree;
int nCells;
int iOvfl;
int lidx; // local idx
SCell *pNewCell;
ASSERT(szCell <= TDB_PAGE_MAX_FREE_BLOCK(pPage, pPage->pPageHdr - pPage->pData));
nFree = TDB_PAGE_NFREE(pPage);
nCells = TDB_PAGE_NCELLS(pPage);
iOvfl = 0;
for (; iOvfl < pPage->nOverflow; iOvfl++) {
if (pPage->aiOvfl[iOvfl] >= idx) {
break;
}
}
lidx = idx - iOvfl;
if (asOvfl || nFree < szCell + TDB_PAGE_OFFSET_SIZE(pPage)) {
// TODO: make it extensible
// add the cell as an overflow cell
for (int i = pPage->nOverflow; i > iOvfl; i--) {
pPage->apOvfl[i] = pPage->apOvfl[i - 1];
pPage->aiOvfl[i] = pPage->aiOvfl[i - 1];
}
// TODO: here has memory leak
pNewCell = (SCell *)tdbOsMalloc(szCell);
memcpy(pNewCell, pCell, szCell);
pPage->apOvfl[iOvfl] = pNewCell;
pPage->aiOvfl[iOvfl] = idx;
pPage->nOverflow++;
iOvfl++;
} else {
// page must has enough space to hold the cell locally
tdbPageAllocate(pPage, szCell, &pNewCell);
memcpy(pNewCell, pCell, szCell);
// no overflow cell exists in this page
u8 *src = pPage->pCellIdx + TDB_PAGE_OFFSET_SIZE(pPage) * lidx;
u8 *dest = src + TDB_PAGE_OFFSET_SIZE(pPage);
memmove(dest, src, pPage->pFreeStart - dest);
TDB_PAGE_CELL_OFFSET_AT_SET(pPage, lidx, pNewCell - pPage->pData);
TDB_PAGE_NCELLS_SET(pPage, nCells + 1);
ASSERT(pPage->pFreeStart == pPage->pCellIdx + TDB_PAGE_OFFSET_SIZE(pPage) * (nCells + 1));
}
for (; iOvfl < pPage->nOverflow; iOvfl++) {
pPage->aiOvfl[iOvfl]++;
}
return 0;
}
int tdbPageDropCell(SPage *pPage, int idx) {
int lidx;
SCell *pCell;
int szCell;
int nCells;
int iOvfl;
nCells = TDB_PAGE_NCELLS(pPage);
ASSERT(idx >= 0 && idx < nCells + pPage->nOverflow);
iOvfl = 0;
for (; iOvfl < pPage->nOverflow; iOvfl++) {
if (pPage->aiOvfl[iOvfl] == idx) {
// remove the over flow cell
for (; (++iOvfl) < pPage->nOverflow;) {
pPage->aiOvfl[iOvfl - 1] = pPage->aiOvfl[iOvfl] - 1;
pPage->apOvfl[iOvfl - 1] = pPage->apOvfl[iOvfl];
}
pPage->nOverflow--;
return 0;
} else if (pPage->aiOvfl[iOvfl] > idx) {
break;
}
}
lidx = idx - iOvfl;
pCell = TDB_PAGE_CELL_AT(pPage, lidx);
szCell = (*pPage->xCellSize)(pPage, pCell);
tdbPageFree(pPage, lidx, pCell, szCell);
TDB_PAGE_NCELLS_SET(pPage, nCells - 1);
for (; iOvfl < pPage->nOverflow; iOvfl++) {
pPage->aiOvfl[iOvfl]--;
ASSERT(pPage->aiOvfl[iOvfl] > 0);
}
return 0;
}
void tdbPageCopy(SPage *pFromPage, SPage *pToPage) {
int delta, nFree;
pToPage->pFreeStart = pToPage->pPageHdr + (pFromPage->pFreeStart - pFromPage->pPageHdr);
pToPage->pFreeEnd = (u8 *)(pToPage->pPageFtr) - ((u8 *)pFromPage->pPageFtr - pFromPage->pFreeEnd);
ASSERT(pToPage->pFreeEnd >= pToPage->pFreeStart);
memcpy(pToPage->pPageHdr, pFromPage->pPageHdr, pFromPage->pFreeStart - pFromPage->pPageHdr);
memcpy(pToPage->pFreeEnd, pFromPage->pFreeEnd, (u8 *)pFromPage->pPageFtr - pFromPage->pFreeEnd);
ASSERT(TDB_PAGE_CCELLS(pToPage) == pToPage->pFreeEnd - pToPage->pData);
delta = (pToPage->pPageHdr - pToPage->pData) - (pFromPage->pPageHdr - pFromPage->pData);
if (delta != 0) {
nFree = TDB_PAGE_NFREE(pFromPage);
TDB_PAGE_NFREE_SET(pToPage, nFree - delta);
}
// Copy the overflow cells
for (int iOvfl = 0; iOvfl < pFromPage->nOverflow; iOvfl++) {
pToPage->aiOvfl[iOvfl] = pFromPage->aiOvfl[iOvfl];
pToPage->apOvfl[iOvfl] = pFromPage->apOvfl[iOvfl];
}
pToPage->nOverflow = pFromPage->nOverflow;
}
int tdbPageCapacity(int pageSize, int amHdrSize) {
int szPageHdr;
if (pageSize < 65536) {
szPageHdr = pageMethods.szPageHdr;
} else {
szPageHdr = pageLargeMethods.szPageHdr;
}
return pageSize - szPageHdr - amHdrSize;
}
static int tdbPageAllocate(SPage *pPage, int szCell, SCell **ppCell) {
SCell *pFreeCell;
u8 *pOffset;
int nFree;
int ret;
int cellFree;
SCell *pCell = NULL;
*ppCell = NULL;
nFree = TDB_PAGE_NFREE(pPage);
ASSERT(nFree >= szCell + TDB_PAGE_OFFSET_SIZE(pPage));
ASSERT(TDB_PAGE_CCELLS(pPage) == pPage->pFreeEnd - pPage->pData);
// 1. Try to allocate from the free space block area
if (pPage->pFreeEnd - pPage->pFreeStart >= szCell + TDB_PAGE_OFFSET_SIZE(pPage)) {
pPage->pFreeEnd -= szCell;
pCell = pPage->pFreeEnd;
TDB_PAGE_CCELLS_SET(pPage, pPage->pFreeEnd - pPage->pData);
goto _alloc_finish;
}
// 2. Try to allocate from the page free list
cellFree = TDB_PAGE_FCELL(pPage);
ASSERT(cellFree == 0 || cellFree > pPage->pFreeEnd - pPage->pData);
if (cellFree && pPage->pFreeEnd - pPage->pFreeStart >= TDB_PAGE_OFFSET_SIZE(pPage)) {
SCell *pPrevFreeCell = NULL;
int szPrevFreeCell;
int szFreeCell;
int nxFreeCell;
int newSize;
for (;;) {
if (cellFree == 0) break;
pFreeCell = pPage->pData + cellFree;
pPage->pPageMethods->getFreeCellInfo(pFreeCell, &szFreeCell, &nxFreeCell);
if (szFreeCell >= szCell) {
pCell = pFreeCell;
newSize = szFreeCell - szCell;
pFreeCell += szCell;
if (newSize >= TDB_PAGE_FREE_CELL_SIZE(pPage)) {
pPage->pPageMethods->setFreeCellInfo(pFreeCell, newSize, nxFreeCell);
if (pPrevFreeCell) {
pPage->pPageMethods->setFreeCellInfo(pPrevFreeCell, szPrevFreeCell, pFreeCell - pPage->pData);
} else {
TDB_PAGE_FCELL_SET(pPage, pFreeCell - pPage->pData);
}
} else {
if (pPrevFreeCell) {
pPage->pPageMethods->setFreeCellInfo(pPrevFreeCell, szPrevFreeCell, nxFreeCell);
} else {
TDB_PAGE_FCELL_SET(pPage, nxFreeCell);
}
}
goto _alloc_finish;
} else {
pPrevFreeCell = pFreeCell;
szPrevFreeCell = szFreeCell;
cellFree = nxFreeCell;
}
}
}
// 3. Try to dfragment and allocate again
tdbPageDefragment(pPage);
ASSERT(pPage->pFreeEnd - pPage->pFreeStart == nFree);
ASSERT(nFree == TDB_PAGE_NFREE(pPage));
ASSERT(pPage->pFreeEnd - pPage->pData == TDB_PAGE_CCELLS(pPage));
pPage->pFreeEnd -= szCell;
pCell = pPage->pFreeEnd;
TDB_PAGE_CCELLS_SET(pPage, pPage->pFreeEnd - pPage->pData);
_alloc_finish:
ASSERT(pCell);
pPage->pFreeStart += TDB_PAGE_OFFSET_SIZE(pPage);
TDB_PAGE_NFREE_SET(pPage, nFree - szCell - TDB_PAGE_OFFSET_SIZE(pPage));
*ppCell = pCell;
return 0;
}
static int tdbPageFree(SPage *pPage, int idx, SCell *pCell, int szCell) {
int nFree;
int cellFree;
u8 *dest;
u8 *src;
ASSERT(pCell >= pPage->pFreeEnd);
ASSERT(pCell + szCell <= (u8 *)(pPage->pPageFtr));
ASSERT(pCell == TDB_PAGE_CELL_AT(pPage, idx));
nFree = TDB_PAGE_NFREE(pPage);
if (pCell == pPage->pFreeEnd) {
pPage->pFreeEnd += szCell;
TDB_PAGE_CCELLS_SET(pPage, pPage->pFreeEnd - pPage->pData);
} else {
if (szCell >= TDB_PAGE_FREE_CELL_SIZE(pPage)) {
cellFree = TDB_PAGE_FCELL(pPage);
pPage->pPageMethods->setFreeCellInfo(pCell, szCell, cellFree);
TDB_PAGE_FCELL_SET(pPage, pCell - pPage->pData);
} else {
ASSERT(0);
}
}
dest = pPage->pCellIdx + TDB_PAGE_OFFSET_SIZE(pPage) * idx;
src = dest + TDB_PAGE_OFFSET_SIZE(pPage);
memmove(dest, src, pPage->pFreeStart - src);
pPage->pFreeStart -= TDB_PAGE_OFFSET_SIZE(pPage);
nFree = nFree + szCell + TDB_PAGE_OFFSET_SIZE(pPage);
TDB_PAGE_NFREE_SET(pPage, nFree);
return 0;
}
static int tdbPageDefragment(SPage *pPage) {
int nFree;
int nCells;
SCell *pCell;
SCell *pNextCell;
SCell *pTCell;
int szCell;
int idx;
int iCell;
nFree = TDB_PAGE_NFREE(pPage);
nCells = TDB_PAGE_NCELLS(pPage);
ASSERT(pPage->pFreeEnd - pPage->pFreeStart < nFree);
// Loop to compact the page content
// Here we use an O(n^2) algorithm to do the job since
// this is a low frequency job.
pNextCell = (u8 *)pPage->pPageFtr;
pCell = NULL;
for (iCell = 0;; iCell++) {
// compact over
if (iCell == nCells) {
pPage->pFreeEnd = pNextCell;
break;
}
for (int i = 0; i < nCells; i++) {
if (TDB_PAGE_CELL_OFFSET_AT(pPage, i) < pNextCell - pPage->pData) {
pTCell = TDB_PAGE_CELL_AT(pPage, i);
if (pCell == NULL || pCell < pTCell) {
pCell = pTCell;
idx = i;
}
} else {
continue;
}
}
ASSERT(pCell != NULL);
szCell = (*pPage->xCellSize)(pPage, pCell);
ASSERT(pCell + szCell <= pNextCell);
if (pCell + szCell < pNextCell) {
memmove(pNextCell - szCell, pCell, szCell);
}
pCell = NULL;
pNextCell = pNextCell - szCell;
TDB_PAGE_CELL_OFFSET_AT_SET(pPage, idx, pNextCell - pPage->pData);
}
ASSERT(pPage->pFreeEnd - pPage->pFreeStart == nFree);
TDB_PAGE_CCELLS_SET(pPage, pPage->pFreeEnd - pPage->pData);
TDB_PAGE_FCELL_SET(pPage, 0);
return 0;
}
/* ---------------------------------------------------------------------------------------------------------- */
typedef struct __attribute__((__packed__)) {
u16 cellNum;
u16 cellBody;
u16 cellFree;
u16 nFree;
} SPageHdr;
typedef struct __attribute__((__packed__)) {
u16 szCell;
u16 nxOffset;
} SFreeCell;
// cellNum
static inline int getPageCellNum(SPage *pPage) { return ((SPageHdr *)(pPage->pPageHdr))[0].cellNum; }
static inline void setPageCellNum(SPage *pPage, int cellNum) {
ASSERT(cellNum < 65536);
((SPageHdr *)(pPage->pPageHdr))[0].cellNum = (u16)cellNum;
}
// cellBody
static inline int getPageCellBody(SPage *pPage) { return ((SPageHdr *)(pPage->pPageHdr))[0].cellBody; }
static inline void setPageCellBody(SPage *pPage, int cellBody) {
ASSERT(cellBody < 65536);
((SPageHdr *)(pPage->pPageHdr))[0].cellBody = (u16)cellBody;
}
// cellFree
static inline int getPageCellFree(SPage *pPage) { return ((SPageHdr *)(pPage->pPageHdr))[0].cellFree; }
static inline void setPageCellFree(SPage *pPage, int cellFree) {
ASSERT(cellFree < 65536);
((SPageHdr *)(pPage->pPageHdr))[0].cellFree = (u16)cellFree;
}
// nFree
static inline int getPageNFree(SPage *pPage) { return ((SPageHdr *)(pPage->pPageHdr))[0].nFree; }
static inline void setPageNFree(SPage *pPage, int nFree) {
ASSERT(nFree < 65536);
((SPageHdr *)(pPage->pPageHdr))[0].nFree = (u16)nFree;
}
// cell offset
static inline int getPageCellOffset(SPage *pPage, int idx) {
ASSERT(idx >= 0 && idx < getPageCellNum(pPage));
return ((u16 *)pPage->pCellIdx)[idx];
}
static inline void setPageCellOffset(SPage *pPage, int idx, int offset) {
ASSERT(offset < 65536);
((u16 *)pPage->pCellIdx)[idx] = (u16)offset;
}
// free cell info
static inline void getPageFreeCellInfo(SCell *pCell, int *szCell, int *nxOffset) {
SFreeCell *pFreeCell = (SFreeCell *)pCell;
*szCell = pFreeCell->szCell;
*nxOffset = pFreeCell->nxOffset;
}
static inline void setPageFreeCellInfo(SCell *pCell, int szCell, int nxOffset) {
SFreeCell *pFreeCell = (SFreeCell *)pCell;
pFreeCell->szCell = szCell;
pFreeCell->nxOffset = nxOffset;
}
SPageMethods pageMethods = {
2, // szOffset
sizeof(SPageHdr), // szPageHdr
sizeof(SFreeCell), // szFreeCell
getPageCellNum, // getCellNum
setPageCellNum, // setCellNum
getPageCellBody, // getCellBody
setPageCellBody, // setCellBody
getPageCellFree, // getCellFree
setPageCellFree, // setCellFree
getPageNFree, // getFreeBytes
setPageNFree, // setFreeBytes
getPageCellOffset, // getCellOffset
setPageCellOffset, // setCellOffset
getPageFreeCellInfo, // getFreeCellInfo
setPageFreeCellInfo // setFreeCellInfo
};
typedef struct __attribute__((__packed__)) {
u8 cellNum[3];
u8 cellBody[3];
u8 cellFree[3];
u8 nFree[3];
} SPageHdrL;
typedef struct __attribute__((__packed__)) {
u8 szCell[3];
u8 nxOffset[3];
} SFreeCellL;
// cellNum
static inline int getLPageCellNum(SPage *pPage) { return TDB_GET_U24(((SPageHdrL *)(pPage->pPageHdr))[0].cellNum); }
static inline void setLPageCellNum(SPage *pPage, int cellNum) {
TDB_PUT_U24(((SPageHdrL *)(pPage->pPageHdr))[0].cellNum, cellNum);
}
// cellBody
static inline int getLPageCellBody(SPage *pPage) { return TDB_GET_U24(((SPageHdrL *)(pPage->pPageHdr))[0].cellBody); }
static inline void setLPageCellBody(SPage *pPage, int cellBody) {
TDB_PUT_U24(((SPageHdrL *)(pPage->pPageHdr))[0].cellBody, cellBody);
}
// cellFree
static inline int getLPageCellFree(SPage *pPage) { return TDB_GET_U24(((SPageHdrL *)(pPage->pPageHdr))[0].cellFree); }
static inline void setLPageCellFree(SPage *pPage, int cellFree) {
TDB_PUT_U24(((SPageHdrL *)(pPage->pPageHdr))[0].cellFree, cellFree);
}
// nFree
static inline int getLPageNFree(SPage *pPage) { return TDB_GET_U24(((SPageHdrL *)(pPage->pPageHdr))[0].nFree); }
static inline void setLPageNFree(SPage *pPage, int nFree) {
TDB_PUT_U24(((SPageHdrL *)(pPage->pPageHdr))[0].nFree, nFree);
}
// cell offset
static inline int getLPageCellOffset(SPage *pPage, int idx) {
ASSERT(idx >= 0 && idx < getPageCellNum(pPage));
return TDB_GET_U24(pPage->pCellIdx + 3 * idx);
}
static inline void setLPageCellOffset(SPage *pPage, int idx, int offset) {
TDB_PUT_U24(pPage->pCellIdx + 3 * idx, offset);
}
// free cell info
static inline void getLPageFreeCellInfo(SCell *pCell, int *szCell, int *nxOffset) {
SFreeCellL *pFreeCell = (SFreeCellL *)pCell;
*szCell = TDB_GET_U24(pFreeCell->szCell);
*nxOffset = TDB_GET_U24(pFreeCell->nxOffset);
}
static inline void setLPageFreeCellInfo(SCell *pCell, int szCell, int nxOffset) {
SFreeCellL *pFreeCell = (SFreeCellL *)pCell;
TDB_PUT_U24(pFreeCell->szCell, szCell);
TDB_PUT_U24(pFreeCell->nxOffset, nxOffset);
}
SPageMethods pageLargeMethods = {
3, // szOffset
sizeof(SPageHdrL), // szPageHdr
sizeof(SFreeCellL), // szFreeCell
getLPageCellNum, // getCellNum
setLPageCellNum, // setCellNum
getLPageCellBody, // getCellBody
setLPageCellBody, // setCellBody
getLPageCellFree, // getCellFree
setLPageCellFree, // setCellFree
getLPageNFree, // getFreeBytes
setLPageNFree, // setFreeBytes
getLPageCellOffset, // getCellOffset
setLPageCellOffset, // setCellOffset
getLPageFreeCellInfo, // getFreeCellInfo
setLPageFreeCellInfo // setFreeCellInfo
};