Can Moka combine entries ?

[lynn2910]

Hello,
I've just discovered this crate and I'm thinking of using it, but I haven't found any information about combining inputs.

To put it simply, for my project, I have data that is not complete, and depending on what I receive from the API, I can update the cache with fields that have changed or are non-existent.
Is this possible with Moka?

[peter-scholtens]

The original author of the crate is hospitalized, see #352.

I think you can solve that problem by making an Arc<Mutex<T>> of your data T and store a clone of that in the cache while holding the original reference. As an example, see how I try to access the same data by Cache and by Btree in example #350

[tatsuya6502]

Sorry for a late reply.

Right, you can solve the problem by making an Arc<Mutex<T>> or Arc<RwLock<T>> of your data T. However there are some limitations on expiration, eviction listener and size-based eviction. This is because you are modifying cached value without calling any cache API so cache's internal data structures like the LRU queue and expiration timers cannot be updated. For more details of the limitations, see the lower part of this issue comment.

To remove such limitations, I am currently working on the following new feature:

• Add the upsert and compute methods for modifying a cached entry #370

You might want to use the and_upsert_with method, although you will still need to use Arc<Mutex<T>> or Arc<RwLock<T>>. For more details, see this example append_value_async.rs in the pull request.

[tatsuya6502]

I am reviewing #370 now and will merge it today. I will publish moka v0.12.3 hopefully in a few days.