Just wanted to say thanks for such a good write-up and the great work on Otter over the years. We've used Ristretto since the beginning of building SpiceDB and have been watching a lot of the progress in this space over time. We've carved out an interface for our cache usage a while back so that we could experiment with Theine, but it just hasn't been a priority. Some of these new features are exciting enough that I could justify an evaluation for Otter v2.

Another major for on-heap caches that wasn't mentioned their portability: for us that matters because they can compile to WebAssembly.

I actually modified SpiceDB to inject a groupcache and Redis cache implementation. My PoC was trying to build a leopard index that could materialize tuples into Redis and then serve them via the dispatch API. I found it easier to just use the aforementioned cache interface and have it delegate to Redis.