private:
void reserve_more();
bool reserve_block(const BlockIter &);
- void advance_to(const Block *);
+ void advance_front(const Block *, bool);
+ void advance_front(const Sensor *);
+ void advance_back();
void release_blocks_begin(const BlockList::iterator &);
void release_blocks_end(const BlockList::iterator &);
void release_block(const BlockList::iterator &);