Internal storage engine api
This API seems to be a subset of Spanner API.
Looks like it's easy to implement it on top of leveldb.
Some rationale:
- strings are used instead of []bytes as strings are immutable;
also returned values can point to char arrays allocated on C side
- writes can be done only as a part of transaction as Spanner and
Sqlite do it anyway, leveldb does a write as a WriteBatch with
one mutation
- no helpers for operations required by sync: for updating object
version read+write should happen anyway; to help simulating commit
log we can use Jatin's time stamps
- I like separation of read-write transactions and snapshots because
of typesafety; also Spanner does it
- I don't see why for transactions we need to have a consistent snapshot
that was taken not later than the first read operation in the
transaction; I feel that snapshot taken at some near future time
will still be OK
- Snapshot has Close() method as some structs may be allocated on C side
and in this case we need to do garbage collecting manually; in order
to get rid of it we can use go finalizers, but they are not as nice
as Java finalizers because you can't attach them in the middle of
your struct
- ResetForRetry is a small optimization in case of leveldb as it's
a bit faster to reuse WriteBatch std::string buffer instead of
allocating new struct; also Spanner has it
The next two steps will be:
1) forward method calls to leveldb, skipping transaction semantics
2) implement in-memory transactions
Change-Id: I0dcec921d57be8d3b5ec03deae9e00652b9bad64
2 files changed
tree: fb26b0e14fc2dc82b098b317573f85be4dbc353e
- services/
