HybridCache serialization issues when in-memory

[BrianVallelunga]

Description

I'm not sure if this is a bug or a misunderstanding, but when storing only locally, why is the data being serialized? I'd assume I could store any sort of object (interfaces, classes, etc) in a local, memory cache.

Reproduction Steps

My factory function returns a Task of an interface (IBloomFilter in this case). I'm passing the HybridCacheEntryFlags.DisableDistributedCache flag into the cache method as follows:

return hybridCache.GetOrCreate("BloomFilter", factory, HybridCacheEntryFlags.DisableDistributedCache)

Expected behavior

The object wouldn't go through serialization when caching locally in memory.

Actual behavior

An exception is thrown: System.NotSupportedException: Deserialization of interface or abstract types is not supported. Type 'BloomFilter.IBloomFilter'

Regression?

No response

Known Workarounds

No response

Configuration

.NET 9, HybridCache 9.2.0-preview1.25105.6

Other information

No response

[Mizuwokiru]

I haven't tested it yet but try to do this:

1. Use a type that has an attribute [ImmutableObject(true)].
2. Use DisableDistributedCache and DisableLocalCacheWrite flags. According to the code here it seems you need DisableLocalCacheWrite flag too to disable local cache serialization.

[BrianVallelunga]

Thanks @Mizuwokiru , but if I set DisableLocalCacheWrite along with DisableDistributedCache then I'm not caching anything at all, right?

[jodydonetti]

To the best of my knowledge, HybridCache tries to be consistent with IDistributedCache in not returning live references, to "avoid surprises". To do that, it serialize/deserialize the result to clone it, basically.

I remember at the beginning there was supposed to be an option to disable this behavior, but right now I don't see it in the docs.

Hope this helps.

[BrianVallelunga]

It would be nice if it could provide a true superset of IMemoryCache's abilities. While I can still use that in my code, using a single caching mechanism would be ideal.

[jodydonetti]

Hi @BrianVallelunga , if in fact there's no way to do that with HybridCache for now, you can take a look at FusionCache (creator here, shameless plug).

You can use it either directly or, if you prefer staying with the HybridCache abstraction, via the available adapter.

Hope this helps.

[snakex64]

Hello! I added a PR to fix this by adding a new "DisableLocalCacheSerialization" flag. The flag is temporarily not in the right place since it required changing the runtime repo (the enum is in the "Abstractions" project, which is not in the same repo as the actual implementation).

Like I described in the PR, I wanted to get the conversation going again before spending more time on it. Feel free to give your opinion :)

#7641