func (v *Volume) get(n *needle.Needle) (err error) { var ( ok bool nc int64 offset uint32 size int32 key = n.Key now = time.Now().UnixNano() ) // pread syscall is atomic, so use rlock v.lock.RLock() if nc, ok = v.needles[key]; ok { if offset, size = needle.Cache(nc); offset != needle.CacheDelOffset { n.TotalSize = size err = v.Block.ReadAt(offset, n) } else { err = errors.ErrNeedleDeleted } } else { err = errors.ErrNeedleNotExist } v.lock.RUnlock() if err != nil { return } if err = n.Parse(); err != nil { return } if n.Key != key { return errors.ErrNeedleKey } if n.TotalSize != size { return errors.ErrNeedleSize } if log.V(1) { log.Infof("get needle key: %d, cookie: %d, offset: %d, size: %d", n.Key, n.Cookie, offset, size) log.Infof("%v\n", n) } // needles map may be out-dated, recheck if n.Flag == needle.FlagDel { v.lock.Lock() v.needles[key] = needle.NewCache(needle.CacheDelOffset, size) v.lock.Unlock() err = errors.ErrNeedleDeleted } else { atomic.AddUint64(&v.Stats.TotalGetProcessed, 1) atomic.AddUint64(&v.Stats.TotalReadBytes, uint64(size)) atomic.AddUint64(&v.Stats.TotalGetDelay, uint64(time.Now().UnixNano()-now)) } return }