ceph源码片段——boost::intrusive_ptr

 //typedef boost::intrusive_ptr<PG> PGRef;
  for (list<PGRef>::iterator i = to_remove.begin();
       i != to_remove.end();
       to_remove.erase(i++)) {
    RWLock::WLocker locker(pg_map_lock);
    (*i)->lock();
    _remove_pg(&**i);//OSD::_remove_pg(PG *pg)
    (*i)->unlock();
  }