Re: (ITS#7771) liblmdb cursor issues

[h.b.furuseth@usit.uio.no]

On 22/12/13 23:09, h.b.furuseth@usit.uio.no wrote:
> I.e. lots more code needs something like
>      if ((leaf->mn_flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA)
>          m2->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
> before using an xcursor.  I tried that everywhere before
> using xcursors: That helped, but it was not enough.  E.g.
> after mdb_cursor_del() calls mdb_node_shrink(), it tracks
> cursors in the same sub-page but not nearby sub-pages.

Such fixups do heal this ITS's test program with current mdb.master,
though.  That is, perl -i -pe '
s/\b(\w+)->mc_xcursor->mx_cursor\./mdb_subcursor($1)->/gx;
s/\&(\w+)->mc_xcursor->mx_cursor/mdb_subcursor($1)/gx;' mdb.c

plus this function:

static MDB_cursor *
mdb_subcursor(MDB_cursor *mc)
{
     MDB_xcursor *mx = mc->mc_xcursor;
     MDB_cursor *subc = NULL;
     MDB_page *mp = mc->mc_pg[mc->mc_top];
     if (mx) {
         subc = &mx->mx_cursor;
         if (((mc->mc_flags | subc->mc_flags) & C_INITIALIZED) &&
             mp && !(mp->mp_flags & (P_BRANCH|P_LEAF2|P_SUBP)))
         {
             MDB_node *leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
             if ((leaf->mn_flags & (F_SUBDATA|F_DUPDATA)) == F_DUPDATA)
                 subc->mc_pg[0] = NODEDATA(leaf);
         }
     }
     return subc;
}