Mixin class for copying transactions into a storage.
The restore() and pack() methods share a need to copy data records and update pointers to data in earlier transaction records. This class provides the shared logic.
The mixin extends the FileStorageFormatter with a copy() method. It also requires that the concrete class provides the following attributes:
_tindex and _tvindex are updated by copy().
The copy() method does not do any locking.
There are no implemented interfaces.
There are no attributes in this class.
checkData(th, tpos, dh, pos)
checkTxn(th, pos)
copy(oid, serial, data, version, prev_txn, txnpos, datapos)
fail(pos, msg, *args)
getTxnFromData(oid, back)
Return transaction id for data at back.