inmem_store.go
func (i *InmemStore) DeleteRange(min, max uint64) error {
	i.l.Lock()
	defer i.l.Unlock()
	for j := min; j <= max; j++ {
		delete(i.logs, j)
	}
	if min <= i.lowIndex {
		i.lowIndex = max + 1
	}
	if max >= i.highIndex {
		i.highIndex = min - 1
	}
	if i.lowIndex > i.highIndex {
		i.lowIndex = 0
		i.highIndex = 0
	}
	return nil
}
func (i *InmemStore) DeleteRange(min, max uint64) error {
	i.l.Lock()
	defer i.l.Unlock()
	for j := min; j <= max; j++ {
		delete(i.logs, j)
	}
	if min <= i.lowIndex {
		i.lowIndex = max + 1
	}
	if max >= i.highIndex {
		i.highIndex = min - 1
	}
	if i.lowIndex > i.highIndex {
		i.lowIndex = 0
		i.highIndex = 0
	}
	return nil
}
// DeleteRange implements the LogStore interface.