hashstash

It's like git but for your Rust data structures.

hashstash provides means to concisely hash and serialize data structures and later de-serialize the same or new data structures, allowing you to capture snapshots in time and rollback to or recreate those states later.

Types that you want to hash or serialize implement the Stashable trait, which uses its single stash method to transparently do both hashing and serializing. Stashed objects are stored in a Stash and referred to via a StashHandle<T>. From a StashHandle<T>, you can recreate new instances of T in the state it was stashed with that handle if T is Unstashable. You can also modify the original object or other objects of type T in-place to recreate the state the handle represents if T is UnstashableInplace. Deserializing objects in place is risky, so UnstashableInplace uses a two- phase approach where stashed contents are read through in a practice run before being read through a second time when the object is actually modified.

Under the hood, hashstash implements a content-addressable storage system in the form of the Stash struct, such that objects with identical hashes are only serialized once. This automatically deduplicates serialized data and means that the marginal cost of stashing the same objects multiple times is free.