remove &mut for regular operations (get)

[joepio]

When getting a resource from a store, the store might not have it locally, and will therefore try to fetch it by sending a request to its subject URL. When this happens, we want to store the newly fetched data to our store for caching. Because of this, any get command can also mutate the store. This is kind of not cool, because &mut references are exclusive. I'm kind of new to rust, but I believe this will prevent that multiple threads can do anything with this same store. This could cause latency spikes that will affect performance.

atomic_lib uses Sled, an embedded Rust key-value database, and it works entirely without mutable references. There must be something to learn here... Interesting video by the creator of sled touching this subject here.

[joepio]

Perhaps related - I want Resource instances to have some connection to a store, but how? I don't want my resource to have an exclusive reference. I'm assuming the answer has something to do with Arc and RwLock.

[joepio]

I think I've got this, but I'm still not sure whether this approach is the right one. Now, getting a resource requires a .lock()