refactor: caching in jsonld processor

[aholovko]

This PR is a proposal on refactoring caching functionality in jsold processor.

There are 2 major issues that I have with the current approach:

• it doesn't save from the repetitive code

Using WithDocumentLoaderCache might look like a robust solution but in practice, it requires a lot of boilerplate code (examples in Trustbloc projects: here, here, and similar should be added to edge-agent).

• problems with API consistency

Cache is preloaded in one case and is not in another: here and here. It's also not necessarily clear that under the hood framework adds some additional opts to ones that you have specified explicitly. There is also hardcoded usage of ld.NewCachingDocumentLoader. The latter is a problem because I might want to use ld.NewCachingDocumentLoader with preloaded contexts and be able to pass it to the processor using WithDocumentLoader(...) - the current implementation will wrap it with one more ld.NewCachingDocumentLoader. UPD: existing code has guards against such scenario here

The current PR simplifies logic and adds more consistency to API. ld.NewCachingDocumentLoader with predefined contexts in the cache is used as a default. You can override it to any loader you want with options. I also moved cache.go from proof package to jsonld - for me it looks more like a processor concern.

Signed-off-by: Andriy Holovko [email protected]

[codecov]

Codecov Report

Merging #2487 (1c929ca) into main (34e1819) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2487      +/-   ##
==========================================
- Coverage   89.29%   89.28%   -0.02%     
==========================================
  Files         250      250              
  Lines       18851    18822      -29     
==========================================
- Hits        16833    16805      -28     
+ Misses       1187     1186       -1     
  Partials      831      831              

Impacted Files	Coverage Δ
pkg/doc/signature/proof/data.go	90.00% <ø> (-0.25%)	⬇️
pkg/doc/signature/jsonld/processor.go	82.03% <100.00%> (-1.99%)	⬇️
pkg/doc/signature/proof/jws.go	89.47% <100.00%> (-0.19%)	⬇️

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[llorllale]

Does this fix #1833?

[aholovko]

Does this fix #1833?

It looks like the mentioned issue describes two problems:

• handling of "JsonWebSignature2020" context

targeted by this PR

• panic when the loader with pre-loaded contexts is used

I am trying to reproduce this panic with the old code. And then check it with the updated one (but I think that the problem has gone).

@llorllale plz correct me if I didn't get it right.

[aholovko]

During the discussion with @kdimak, we decided that the caching functionality requires more consideration and also should account for other issues like the one mentioned by George. I am closing the current PR as it doesn't bring enough benefits to justify the risk of breaking the core stuff.