more TDB

source/libs/tdb/src/db/tdbBtree.c

@@ -752,13 +752,6 @@ static int tdbBtreeBalance(SBtCursor *pCur) {
     leaf = TDB_BTREE_PAGE_IS_LEAF(flags);
     root = TDB_BTREE_PAGE_IS_ROOT(flags);
 
-    // TODO: Get the page free space if not get yet
-    // if (pPage->nFree < 0) {
-    //   if (tdbBtreeComputeFreeSpace(pPage) < 0) {
-    //     return -1;
-    //   }
-    // }
-
     // when the page is not overflow and not too empty, the balance work
     // is finished. Just break out the balance loop.
     if (pPage->nOverflow == 0 /* TODO: && pPage->nFree <= */) {

source/libs/tdb/src/inc/tdbPage.h

@@ -107,6 +107,7 @@ void tdbPageZero(SPage *pPage, u8 szAmHdr, int (*xCellSize)(const SPage *, SCell
 void tdbPageInit(SPage *pPage, u8 szAmHdr, int (*xCellSize)(const SPage *, SCell *));
 int  tdbPageInsertCell(SPage *pPage, int idx, SCell *pCell, int szCell);
 int  tdbPageDropCell(SPage *pPage, int idx);
+void tdbPageCopy(SPage *pFromPage, SPage *pToPage);
 
 static inline SCell *tdbPageGetCell(SPage *pPage, int idx) {
   SCell *pCell;

source/libs/tdb/src/page/tdbPage.c

@@ -207,6 +207,16 @@ int tdbPageDropCell(SPage *pPage, int idx) {
   return 0;
 }
 
+void tdbPageCopy(SPage *pFromPage, SPage *pToPage) {
+  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);
+}
+
 static int tdbPageAllocate(SPage *pPage, int szCell, SCell **ppCell) {
   SCell *pFreeCell;
   u8    *pOffset;