LMDB has a mode designed to do something similar, if anyone wants something like this with just a bit more structure to it like transactional updates via CoW an

LMDB has a mode designed to do something similar, if anyone wants something like this with just a bit more structure to it like transactional updates via CoW and garbage collection of old versions. It's single writer via a lock but readers are lock/coordination free. A long running read transaction can delay garbage collection however.