unique

type IDStore interface {
	io.Closer

	// Get returns the value by given key, if not exist return false.
	Get(key []byte) ([]byte, bool, error)
	// Put puts the value into store by given key.
	Put(key, val []byte) error
	// Merge puts the value into store by given key, if the key exist, will merge value in background.
	Merge(key, val []byte) error
	// Delete deletes the value by given key.
	Delete(key []byte) error
	// IterKeys iterates the key list by given prefix, returns the key list.
	IterKeys(prefix []byte, limit int) (rs [][]byte, err error)
	// Flush flushes the memory table data under pebble db.
	Flush() error
}

type Sequence interface {
	// HasNext checks if it has sequence in cache.
	HasNext() bool
	// Next returns next sequence from cache.
	Next() uint32
	// Current returns current sequence from cache.
	Current() uint32
	// Limit sets new limit value.
	Limit(limit uint32)
}