There is a need to open Blobovnicza instances in read-only mode in some
cases.
Add `ReadOnly` option. Do not create dir path in RO. Open underlying BoltDB
instance with ReadOnly flag. Document thal all writing operations should not
be called in ro (otherwise BoltDB txs fail).
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
In previous implementation `Blobovnicza.Iterate` op decoded object data only
and passed it to the handler. There is a need to iterate over all addresses
of the stored objects.
Add `DecodeAddresses` and `WithoutData` methods of `IteratePrm` type. Add
`Address` method to `IterationElement` type. Make `Iterate` to decode object
addresses if `DecodeAddress` was called and not read the data if
`WithoutData` was called. Implement `IterateAddresses` helper function to
simplify the code.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
In previous implementation Blobovnicza's stored objects in protocol format
which did not allow working with externally compressed objects. To achieve
this goal, operations Get and Put no longer work with the structure of the
object, but only with abstract binary data. Operation GetRange has become
incorrect in its original purpose to receive the payload range. In this
regard, BlobStor receives the payload range of the object through Get
operation. In the future either Blobovnicza will learn to compress objects
by itself, or the GetRange operation will be eliminated.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
