feat: encode/decode anything as root value

[Chuckame]

This PR needed a big refactor to handle easily

• Now able to encode/decode anything as root value (not only records) such as maps, lists, primitives, value classes... (closes #80 and #116)
• Handle value classes and contextual (that encodes as string) for map keys (closes #114)
• No reflection at all, only kotlinx serializers & descriptors and improve naming by using @SerialName for namespace and record name when contains dots (closes #148 and #151)
• Handle unions on kotlin primitive fields (by example: if the given field schema is a union with an int, while calling encodeInt, then it's working)
• Encode by default char (code), byte and short to an avro int (was implicit before for byte and char)
• value classes 100% handled (so AvroInline removed as it prevent native value class serializers to work well) closes #131
• fields of kotlin classes are not forced to be in same order of avro schema fields
• unified and refactored encoders, decoders, schema generation and Avro user entry point. Pay attention of deprecations

147 partially done (encoder & decoder only). We still have one use case of reflection in schema generation, but will be done into another PR

[Chuckame]

Hey @thake , I'll leave some comments to let you focus or understand some specificities. I tried my best to touch on encoders classes, then decoders classes, then schemas classes.

I don't really know how to split this mess since a lot of things permits the new features together.

Except the encode everything in root, I'll put it into another commit (or PR, but it will need this PR to be merged...)

[Chuckame]

Next step: add some tests for the new features, and implement decode stuff

[thake]

Thanks, @Chuckame! I will look at it as soon as it is ready to merge if this is ok for you. I'm working on a PoC for encoding/decoding without avro library. I'll push a branch of it soon.

[Chuckame]

Cool @thake ! By the way, the work I've did on the encoder/decoder classes will help a lot to really easily encode and decode without using apache library, I would advice you to have a look, it's a common structure when doing kotlinx serialization 🚀

[Chuckame]

@thake It's ready for review. FYI, I will scope this PR only for encoders & decoders about the refactoring. But the main features are covered (read the PR description, there is all the fixes). Schemas are already handling everything as root, but with some reflection and weird stuff with custom serial descriptor. I have the solution (WIP), I'll create another PR !

Hope you'll appreciate this work 😄

btw, I won't have the time this 2 next days to make the benchmark, but it would be interesting. I think there is no real big improvement, but a lot of little things, especially the array/map allocation that is better, and naming that should be much less cpu intensive... Let's see !

[thake]

Just to let you know about how I work with GitHub PRs so that we don't have a misunderstanding: If I have submitted a review result, I won't look at the PR again until you "Re-request review".

So whenever you feel ready, just re-request my review :rocket:

[Chuckame]

Ok, good point 👍 I'm currently taking a pause about avro4k, I'll continue working on it in 1-2 weeks 😄

[Chuckame]

There is too much changes, I'll do some other atomic PRs instead of this big-bang PR

[thake]

Let's consolidate our efforts on this topic, because https://github.com/avro-kotlin/avro4k/tree/way-to-multiplatform also includes a fix for this problem.

[Chuckame]

I think first we should work to improve performance and readability as currently it's very difficult to add feature (kotlinx serialization framework not really well used), then maybe removing the avro lib dependency, and thinking about multiplatform.