func (db *DB) zrank(key []byte, member []byte, reverse bool) (int64, error) { if err := checkZSetKMSize(key, member); err != nil { return 0, err } k := db.zEncodeSetKey(key, member) it := db.bucket.NewIterator() defer it.Close() if v := it.Find(k); v == nil { return -1, nil } else { if s, err := Int64(v, nil); err != nil { return 0, err } else { var rit *store.RangeLimitIterator sk := db.zEncodeScoreKey(key, member, s) if !reverse { minKey := db.zEncodeStartScoreKey(key, MinScore) rit = store.NewRangeIterator(it, &store.Range{minKey, sk, store.RangeClose}) } else { maxKey := db.zEncodeStopScoreKey(key, MaxScore) rit = store.NewRevRangeIterator(it, &store.Range{sk, maxKey, store.RangeClose}) } var lastKey []byte = nil var n int64 = 0 for ; rit.Valid(); rit.Next() { n++ lastKey = rit.BufKey(lastKey) } if _, m, _, err := db.zDecodeScoreKey(lastKey); err == nil && bytes.Equal(m, member) { n-- return n, nil } } } return -1, nil }