open_lmdb_env
ret = open_lmdb_env(context, dbc, FALSE, readonly, &dbc->env);
ret = open_lmdb_env(context, dbc, TRUE, readonly, &dbc->lockout_env);
ret = open_lmdb_env(context, dbc, FALSE, FALSE, &dbc->env);
ret = open_lmdb_env(context, dbc, TRUE, FALSE, &dbc->lockout_env);