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
}
