| // Package idm manages reservation/release of numerical ids from a configured set of contiguous ids |
| package idm |
| |
| import ( |
| "errors" |
| "fmt" |
| |
| "github.com/docker/libnetwork/bitseq" |
| "github.com/docker/libnetwork/datastore" |
| ) |
| |
| // Idm manages the reservation/release of numerical ids from a contiguous set |
| type Idm struct { |
| start uint64 |
| end uint64 |
| handle *bitseq.Handle |
| } |
| |
| // New returns an instance of id manager for a [start,end] set of numerical ids |
| func New(ds datastore.DataStore, id string, start, end uint64) (*Idm, error) { |
| if id == "" { |
| return nil, errors.New("Invalid id") |
| } |
| if end <= start { |
| return nil, fmt.Errorf("Invalid set range: [%d, %d]", start, end) |
| } |
| |
| h, err := bitseq.NewHandle("idm", ds, id, 1+end-start) |
| if err != nil { |
| return nil, fmt.Errorf("failed to initialize bit sequence handler: %s", err.Error()) |
| } |
| |
| return &Idm{start: start, end: end, handle: h}, nil |
| } |
| |
| // GetID returns the first available id in the set |
| func (i *Idm) GetID() (uint64, error) { |
| if i.handle == nil { |
| return 0, errors.New("ID set is not initialized") |
| } |
| ordinal, err := i.handle.SetAny() |
| return i.start + ordinal, err |
| } |
| |
| // GetSpecificID tries to reserve the specified id |
| func (i *Idm) GetSpecificID(id uint64) error { |
| if i.handle == nil { |
| return errors.New("ID set is not initialized") |
| } |
| |
| if id < i.start || id > i.end { |
| return errors.New("Requested id does not belong to the set") |
| } |
| |
| return i.handle.Set(id - i.start) |
| } |
| |
| // GetIDInRange returns the first available id in the set within a [start,end] range |
| func (i *Idm) GetIDInRange(start, end uint64) (uint64, error) { |
| if i.handle == nil { |
| return 0, errors.New("ID set is not initialized") |
| } |
| |
| if start < i.start || end > i.end { |
| return 0, errors.New("Requested range does not belong to the set") |
| } |
| |
| ordinal, err := i.handle.SetAnyInRange(start-i.start, end-i.start) |
| |
| return i.start + ordinal, err |
| } |
| |
| // Release releases the specified id |
| func (i *Idm) Release(id uint64) { |
| i.handle.Unset(id - i.start) |
| } |