// set/reset the bit
func (h *Handle) set(ordinal, start, end uint64, any bool, release bool) (uint64, error) {
var (
bitPos uint64
bytePos uint64
ret uint64
err error
)
for {
var store datastore.DataStore
h.Lock()
store = h.store
h.Unlock()
if store != nil {
if err := store.GetObject(datastore.Key(h.Key()...), h); err != nil && err != datastore.ErrKeyNotFound {
return ret, err
}
}
h.Lock()
// Get position if available
if release {
bytePos, bitPos = ordinalToPos(ordinal)
} else {
if any {
bytePos, bitPos, err = getFirstAvailable(h.head, start)
ret = posToOrdinal(bytePos, bitPos)
if end < ret {
err = ErrNoBitAvailable
}
} else {
bytePos, bitPos, err = checkIfAvailable(h.head, ordinal)
ret = ordinal
}
}
if err != nil {
h.Unlock()
return ret, err
}
// Create a private copy of h and work on it
nh := h.getCopy()
h.Unlock()
nh.head = pushReservation(bytePos, bitPos, nh.head, release)
if release {
nh.unselected++
} else {
nh.unselected--
}
// Attempt to write private copy to store
if err := nh.writeToStore(); err != nil {
if _, ok := err.(types.RetryError); !ok {
return ret, fmt.Errorf("internal failure while setting the bit: %v", err)
}
// Retry
continue
}
// Previous atomic push was succesfull. Save private copy to local copy
h.Lock()
defer h.Unlock()
h.unselected = nh.unselected
h.head = nh.head
h.dbExists = nh.dbExists
h.dbIndex = nh.dbIndex
return ret, nil
}
}
