Invalidating Cache

[draganbozhinoski]

Hello,
I would like to ask if there is any way to invalidate caches on context changes(add or update or delete etc). I was going through the docs but did not find anything.

Thank you in advance.

[jodydonetti]

Hi @draganbozhinoski , do you mean invalidating single entries or the entire cache?

[jodydonetti]

No, not that I'm aware of, at least not yet.

[olliejm]

You may want to take a look at EFCoreSecondLevelCacheInterceptor. You'll need to write an implementation of IEFCacheServiceProvider for FusionCache, like an EFFusionCacheProvider then:

services.AddEFSecondLevelCache(options =>
{
    options.UseCustomCacheProvider<EFFusionCacheProvider>();
    // Other options here...
}

This setup works for us. The implementation of EFFusionCacheProvider is trivial, you can easily derive it from e.g. the EasyCaching.Core provider.

It's worth noting that this probably reverses the way you'd normally expect to work with the cache, and how e.g. the Fusion docs will show utilising the cache. You instead call EFCore/Linq at the higher level, and caching happens underneath via interception, rather than primarily interacting with the cache and passing factories to optionally go to DB.

[jodydonetti]

Hi @olliejm , thanks for chipping in!

I know about EFCoreSecondLevelCacheInterceptor and I'm looking at that from some time now, but from what I saw the current roadblock is this, which is not possible with FusionCache since there's no native Clear() method available (for good reasons).

I'm thinking about alternatives, but for now I haven't found any, do you happen to have any idea?

Thanks!

[olliejm]

Hey, yeah you are correct - I encountered the missing Clear() and assumed it was missing for a reason.

For now I ignored it, after analysing the EasyCaching.Core provider's Clear() implementation and seeing that execution is skipped for the EasyCaching hybrid caching mode.

With Fusion also being a hybrid cache, I assumed the reason for missing Clear() is related to the specifics of hybrid caching, and that given the official EasyCaching provider skips in that case, that it would also be OK (or at least not drastically bad) for us to skip.

So our implementation is a no-op currently.

I'm aware I made a bunch of potentially bad assumptions there, but so far we didn't encounter any obvious problems. You may well have a better picture than me about whether those assumptions are sound or not.

I'll take a look at related issues regarding Clear().

[jodydonetti]

Hi @olliejm , I think we'll have news about an EFCoreSecondLevelCacheInterceptor impl after v2 will come out soon 😬 (it will include both Tagging and Clear support).