SQLite

/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.446 2008/03/25 14:24:57 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

    */
    assert( !pBt->pCursor );
    sqlite3PagerClose(pBt->pPager);
    if( pBt->xFreeSchema && pBt->pSchema ){
      pBt->xFreeSchema(pBt->pSchema);
    }
    sqlite3_free(pBt->pSchema);
    sqlite3_free(pBt->pTmpSpace);
    sqlite3_free(pBt);
  }

#ifndef SQLITE_OMIT_SHARED_CACHE
  assert( p->wantToLock==0 );
  assert( p->locked==0 );
  if( p->pPrev ) p->pPrev->pNext = p->pNext;

    nReserve = pBt->pageSize - pBt->usableSize;
  }
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
    assert( (pageSize & 7)==0 );
    assert( !pBt->pPage1 && !pBt->pCursor );
    pBt->pageSize = pageSize;
    sqlite3_free(pBt->pTmpSpace);
    pBt->pTmpSpace = 0;
    rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
  }
  pBt->usableSize = pBt->pageSize - nReserve;
  sqlite3BtreeLeave(p);
  return rc;
}

      ** actually pageSize. Unlock the database, leave pBt->pPage1 at
      ** zero and return SQLITE_OK. The caller will call this function
      ** again with the correct page-size.
      */
      releasePage(pPage1);
      pBt->usableSize = usableSize;
      pBt->pageSize = pageSize;
      sqlite3_free(pBt->pTmpSpace);
      pBt->pTmpSpace = 0;
      sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
      return SQLITE_OK;
    }
    if( usableSize<500 ){
      goto page1_init_failed;
    }
    pBt->pageSize = pageSize;

      }
    }else if( p->pPage->pgno!=p->pgnoRoot ){
      moveToRoot(p);
    }
  }
  return SQLITE_OK;
}

/*
** Make sure pBt->pTmpSpace points to an allocation of 
** MX_CELL_SIZE(pBt) bytes.
*/
static void allocateTempSpace(BtShared *pBt){
  if( !pBt->pTmpSpace ){
    pBt->pTmpSpace = sqlite3_malloc(MX_CELL_SIZE(pBt));
  }
}

/*
** Insert a new record into the BTree.  The key is given by (pKey,nKey)
** and the data is given by (pData,nData).  The cursor is used only to
** define what table the record should be inserted into.  The cursor
** is left pointing at a random location.
**

  pPage = pCur->pPage;
  assert( pPage->intKey || nKey>=0 );
  assert( pPage->leaf || !pPage->leafData );
  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
          pCur->pgnoRoot, nKey, nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );
  allocateTempSpace(pBt);
  newCell = pBt->pTmpSpace;
  if( newCell==0 ) return SQLITE_NOMEM;
  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
  if( rc ) goto end_insert;
  assert( szNew==cellSizePtr(pPage, newCell) );
  assert( szNew<=MX_CELL_SIZE(pBt) );
  if( loc==0 && CURSOR_VALID==pCur->eState ){
    u16 szOld;

  rc = balance(pPage, 1);
  /* sqlite3BtreePageDump(pCur->pBt, pCur->pgnoRoot, 1); */
  /* fflush(stdout); */
  if( rc==SQLITE_OK ){
    moveToRoot(pCur);
  }
end_insert:

  return rc;
}

/*
** Delete the entry that the cursor is pointing to.  The cursor
** is left pointing at a random location.
*/

      u16 szNext;
      TRACE(("DELETE: table=%d delete internal from %d replace from leaf %d\n",
         pCur->pgnoRoot, pPage->pgno, leafCur.pPage->pgno));
      dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
      pNext = findCell(leafCur.pPage, leafCur.idx);
      szNext = cellSizePtr(leafCur.pPage, pNext);
      assert( MX_CELL_SIZE(pBt)>=szNext+4 );
      allocateTempSpace(pBt);
      tempCell = pBt->pTmpSpace;
      if( tempCell==0 ){
        rc = SQLITE_NOMEM;
      }
      if( rc==SQLITE_OK ){
        rc = insertCell(pPage, pCur->idx, pNext-4, szNext+4, tempCell, 0);
      }
      if( rc==SQLITE_OK ){
        put4byte(findOverflowCell(pPage, pCur->idx), pgnoChild);
        rc = balance(pPage, 0);
      }
      if( rc==SQLITE_OK ){
        dropCell(leafCur.pPage, leafCur.idx, szNext);
        rc = balance(leafCur.pPage, 0);
      }
    }

    sqlite3BtreeReleaseTempCursor(&leafCur);
  }else{
    TRACE(("DELETE: table=%d delete from leaf %d\n",
       pCur->pgnoRoot, pPage->pgno));
    dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
    rc = balance(pPage, 0);
  }

/*
** 2004 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btreeInt.h,v 1.19 2008/03/25 14:24:57 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

  BusyHandler busyHdr;  /* The busy handler for this btree */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nRef;             /* Number of references to this structure */
  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
  Btree *pExclusive;    /* Btree with an EXCLUSIVE lock on the whole db */
#endif
  u8 *pTmpSpace;        /* BtShared.pageSize bytes of space for tmp use */
};

/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure
** based on information extract from the raw disk page.
*/