JSON Encoding Performance

[osiegmar]

Discussed in #83

^{Originally posted by pschichtel June 22, 2022}
As part of the performance work I've been doing on the project I work on, I ended up completely rewriting the GelfEncoder to avoid allocations and remove overhead.

https://gist.github.com/pschichtel/cb5556b9d5b681e1e77afabb749186e9

I implemented it using Jackson and Kotlin, since we are using those anyway, so I don't expect any of this to be merged.

This implementation is significantly faster and generates a lot fewer objects then the original one.

However while implementing this I noticed two "issues":

1. the gelf version constant is not accessible
2. the GelfUdpAppender (I assume the same to be the case for the others) expect a subclass of GelfEncoder

The former could easily be solved by making it a public constant, not so sure about the latter, but it is also not really a problem.

[osiegmar]

I made some changes locally but in the end I decided to keep the code as it is (for maintainability reasons).