bitmagnet/internal/bloom/stable.go

package bloom

import (
	"database/sql/driver"
	"errors"
	boom "github.com/tylertreat/BoomFilters"
)

type StableBloomFilter struct {
	boom.StableBloomFilter
}

const defaultCapacity = 100_000_000
const defaultD = 2
const defaultFpRate = 0.001

func NewDefaultStableBloomFilter() *StableBloomFilter {
	return &StableBloomFilter{*boom.NewStableBloomFilter(defaultCapacity, defaultD, defaultFpRate)}
}

func (s *StableBloomFilter) Scan(value interface{}) error {
	bytes, ok := value.([]byte)
	if !ok {
		return errors.New("invalid type for StableBloomFilter")
	}
	bf := boom.NewStableBloomFilter(0, 0, 0)
	if err := bf.GobDecode(bytes); err != nil {
		return err
	}
	s.StableBloomFilter = *bf
	return nil
}

func (s StableBloomFilter) Value() (driver.Value, error) {
	if s.Cells() == 0 {
		return nil, nil
	}
	return s.GobEncode()
}