Add cache support to DidResolver

[bnonni]

Add DIDCache to constructor method signature.

https://github.com/TBD54566975/dwn-sdk-js/blob/fcea84929e12dd3e3ef0e8866b0e592a025786fa/src/did/did-resolver.ts#L9-L17

[thehenrytsai]

High level requirements:

1. Inject the cache via constructor
2. We've implemented an in-memory cache that can be used as the default cache.

[Cxxshyy]

i'd like to try this out if someone could guide me

[thehenrytsai]

@Cxxshyy, the idea is to:

1. Every time DID resolution occurs, check the cache first to see if there is a match:
2. If there is match, just return the cached result; if not
3. Proceed with normal path of fetching the document from the method resolver, and then cache the result.

Let me know if I am not making sense!

[Cxxshyy]

yes i think so. 1st i add the resolvers to the local cache using the set method then in the resolve method i add the get function from cache to check whether the resolver is currently residing in cache at that point in time? elt me know if this is correct.

[thehenrytsai]

No no, it's not the list of DidMethodResolver themselves that need caching, it's the result returned by the resolve(...) call, specfically:

const resolutionResult = await didResolver.resolve(did);

resolve(...) is possibly expensive, so adding a cache in front of it would help with perf. Let me know if this still does not make sense.

[Cxxshyy]

oh yes that's what i meant by my explanation but i guess i didn't convey it great sorry.

[Cxxshyy]

#124 aims to tackle this issue

[Cxxshyy]

im now getting this error

[Cxxshyy]

although this file hasnt been modified

[thehenrytsai]

I think you pulled recently, but you'll also need to do an npm install 'coz dependencies have changed.

[thehenrytsai]

Addressed by #155.