The statedb package provides a transactional in-memory database with per-table locking. The database indexes objects using Persistive Adaptive Radix Trees. (https://db.in.tum.de/~leis/papers/ART.pdf) As this is built around an immutable data structure and objects may have lockless readers the stored objects MUST NOT be mutated, but instead a copy must be made prior to mutation and insertion. See 'example/' for an example how to construct an application that uses this library.