OutputCaching extension cache stampede

[WeihanLi]

From the OutputCaching extension code

https://github.com/ZiggyCreatures/FusionCache/blob/0d424995e99874ed5ece4a9057612e4a8237fa3a/src/ZiggyCreatures.FusionCache.AspNetCore.OutputCaching/FusionOutputCacheStore.cs

seems it would not use the GetOrSet(Async) method which would avoid cache stampede

If we want to avoid the cache stampede, do we need to implement a customized output caching middleware?

[jodydonetti]

Hi @WeihanLi

seems it would not use the GetOrSet(Async) method which would avoid cache stampede

Correct, but 2 important things here:

• to support Output Caching what is needed is to implement the IOutputCacheStore interface, and that interface only has 3 methods to implement (see here): GetAsync, SetAsync and EvictByTagAsync
• cache stampede protection is built in the Output Cache system itself, not in the provider abstraction, so yo ustill have it (and is enabled by default, see here)

The aspnet team designed the interface that way, so there's nothing I can do to use the FusionCache version of the stampede protection.
I understand why they did that, I think the rationale was to have the stampede protection "for free" without the need for each implementer of the provider to re-implement it.

NOTE: a different design that may have been more powerful would have been to also have a GetOrSetAsync method in the interface, and provide an abstract class with the GetOrSetAsync method already implemented. In this way implementers could choose to only implement get/set/evict-by-tag and have the built in stampede protection, or implement everything if they want to go the extra mile. But this is what we have.

Hope this helps.

[WeihanLi]

Really helpful, thanks very much