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Changes to src/btree.c.

   625    625       pCur->eState = CURSOR_REQUIRESEEK;
   626    626     }
   627    627   
   628    628     invalidateOverflowCache(pCur);
   629    629     return rc;
   630    630   }
   631    631   
          632  +/* Forward reference */
          633  +static int SQLITE_NOINLINE saveCursorsOnList(BtCursor*,Pgno,BtCursor*);
          634  +
   632    635   /*
   633    636   ** Save the positions of all cursors (except pExcept) that are open on
   634         -** the table  with root-page iRoot. Usually, this is called just before cursor
   635         -** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
          637  +** the table with root-page iRoot.  "Saving the cursor position" means that
          638  +** the location in the btree is remembered in such a way that it can be
          639  +** moved back to the same spot after the btree has been modified.  This
          640  +** routine is called just before cursor pExcept is used to modify the
          641  +** table, for example in BtreeDelete() or BtreeInsert().
          642  +**
          643  +** Implementation note:  This routine merely checks to see if any cursors
          644  +** need to be saved.  It calls out to saveCursorsOnList() in the (unusual)
          645  +** event that cursors are in need to being saved.
   636    646   */
   637    647   static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
   638         -  BtCursor *p;
   639    648     assert( sqlite3_mutex_held(pBt->mutex) );
   640    649     assert( pExcept==0 || pExcept->pBt==pBt );
          650  +  BtCursor *p;
   641    651     for(p=pBt->pCursor; p; p=p->pNext){
          652  +    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ) break;
          653  +  }
          654  +  return p ? saveCursorsOnList(p, iRoot, pExcept) : SQLITE_OK;
          655  +}
          656  +
          657  +/* This helper routine to saveAllCursors does the actual work of saving
          658  +** the cursors if and when a cursor is found that actually requires saving.
          659  +** The common case is that no cursors need to be saved, so this routine is
          660  +** broken out from its caller to avoid unnecessary stack pointer movement.
          661  +*/
          662  +static int SQLITE_NOINLINE saveCursorsOnList(
          663  +  BtCursor *p,           /* The first cursor that needs saving */
          664  +  Pgno iRoot,            /* Only save cursor with this iRoot.  Save all if zero */
          665  +  BtCursor *pExcept      /* Do not save this cursor */
          666  +){
          667  +  do{
   642    668       if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) ){
   643    669         if( p->eState==CURSOR_VALID ){
   644    670           int rc = saveCursorPosition(p);
   645    671           if( SQLITE_OK!=rc ){
   646    672             return rc;
   647    673           }
   648    674         }else{
   649    675           testcase( p->iPage>0 );
   650    676           btreeReleaseAllCursorPages(p);
   651    677         }
   652    678       }
   653         -  }
          679  +    p = p->pNext;
          680  +  }while( p );
   654    681     return SQLITE_OK;
   655    682   }
   656    683   
   657    684   /*
   658    685   ** Clear the current cursor position.
   659    686   */
   660    687   void sqlite3BtreeClearCursor(BtCursor *pCur){