keeping stale values in case the backend is offline

[barkanido]

Hey,
First, thanks for this great library.
I would like to configure Caffeine to save stale values in case the backend is off. This means if you cache a DB query and the DB query, and the DB goes offline for some reason. The cache would preserve the same values even after they are considered stale. This is because, in a few use cases, a stale value is better than no value.
This is doable with refreshAfterWrite but this API is not as flexible as expireAfter. This might be a duplicate of #360 but I wonder if there is another way (even if less straightforward) of doing so.

[ben-manes]

Perhaps a victim cache would work? In that case when the writer synchronously evicts, you capture it into a secondary cache. A subsequent loader call could fetch it, resurrecting the entry. That might provide the lifecycle hack that you’re looking for.

[barkanido]

in that case when the writer synchronously evicts...

which writer? do you mean an external thread that invalidates the cache?

[ben-manes]

I meant if you supply a CacheWriter.

[barkanido]

do you mean a configuration like your comment here?

[ben-manes]

Yes, something like that might work?

[barkanido]

I think it might work. thanks!

[VytautasSer]

Hello,

Have you found a solution to this problem? Could you share it? Sad that there is no such thing out of the box.

[barkanido]

Look in the example above by @ben-manes . also, note that with a loadingCache, a backend failure will throw an exception and the mapping is unchanged so you get the old value by default (if it was there already)