quarkus-cache programmatic API

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gwe...@gmail.com

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Nov 20, 2021, 5:58:58 PM11/20/21
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Hi everyone,

The annotations caching API from the quarkus-cache extension has been around for a while and since it was released almost 2 years ago, Quarkus users asked for a programmatic caching API multiple times.

Let's talk about the current oldest open PR in the Quarkus repo which contains a proposal for that API: https://github.com/quarkusio/quarkus/pull/8631.

Since #8631 already received quite a lot of comments, I'll try to make this discussion easier by summarizing below the main changes from that proposal. Before you continue reading this, I encourage you to read the #8631 doc update which includes several code examples explaining how to use the new API.

Here's also a reminder of a few undocumented parts of the programmatic API that have already been merged a while ago:
- It is already possible to inject a Cache bean (main branch link) in any CDI managed bean using the @CacheName qualifier (main branch link) as shown in the #8631 doc update.
- Injecting the CacheManager (main branch link) and then retrieving a Cache from its name is also possible already. This is also explained in the doc update.
However, in both cases the injected or retrieved cache cannot be used as-is because the Cache interface does not contain any method. This is where #8631 kicks in.

#8631 introduces the following methods in the Cache interface (#8631 link):

public interface Cache {
    String getName();
    Object getDefaultKey();
    <K, V> Uni<V> get(K key, Function<K, V> valueLoader);
    Uni<Void> invalidate(Object key);
    Uni<Void> invalidateAll();
    <T extends Cache> T asSpecializedCache(Class<T> type);
}

As you can see in the new signatures, the programmatic API main operations are asynchronous and depend on Mutiny.

#8631 also introduces the CaffeineCache interface which is meant to contain methods specific to the Caffeine caching provider which is currently the only available provider:

public interface CaffeineCache extends Cache {
    Set<Object> keySet();
}

As I suggested here, an alternative approach could consist in moving most of the Cache interface methods to the CaffeineCache interface:

public interface Cache {
    <T extends Cache> T asSpecializedCache(Class<T> type);
}

public interface CaffeineCache extends Cache {
    String getName(); // This could stay in Cache
    Object getDefaultKey(); // This as well
    <K, V> Uni<V> get(K key, Function<K, V> valueLoader);
    Uni<Void> invalidate(Object key);
    Uni<Void> invalidateAll();
    Set<Object> keySet();
}

That approach would probably make things easier if we wanted to add a new caching provider to the extension while still supporting Caffeine.

Now here comes my question to you, dear Quarkus community. Is it worth merging #8631 (with or without changes) or should that PR simply be closed? It's been open for a very long time and it looks pretty much ready to me.

What do you think?

Gwenneg

Georgios Andrianakis

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Nov 22, 2021, 2:49:53 AM11/22/21
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I haven't been involved in that much, but from the looks of it, I would say it should be rebased and merged.

What do you think?

Gwenneg

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Sérgio Sousa

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Nov 22, 2021, 3:51:01 AM11/22/21
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Gwenneg LEPAGE

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Nov 23, 2021, 3:51:16 PM11/23/21
to Sérgio Sousa, Georgios Andrianakis, Quarkus Development mailing list
Thank you for your answers.

@geoand I rebased the PR and fixed all conflicts.

Gwenneg
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