ability to pass context to serialization (pydantic#7143)

[ornariece]

Change Summary

As described and discussed in pydantic#7143, it would make sense to be able to pass a context object to .model_dump()/.model_dump_json() in order to dynamically update the serialization behavior during runtime.
This PR is my attempt at implementing this feature. This is my first time with Rust, so you should be wary about it :).
I tested this implementation with (an accordingly-modified) pydantic and everything seemed to work.

Related issue number

pydantic#7143
The pydantic side of the change is very light, I have a commit ready for it in case this PR gets merged.

Checklist

• Unit tests for the changes exist
• Documentation reflects the changes where applicable
• Pydantic tests pass with this pydantic-core (except for expected changes)
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @adriangb

[codecov]

Codecov Report

Merging #1215 (617d086) into main (ab503cb) will decrease coverage by 0.36%.
Report is 28 commits behind head on main.
The diff coverage is 28.03%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1215      +/-   ##
==========================================
- Coverage   90.21%   89.86%   -0.36%     
==========================================
  Files         106      106              
  Lines       16339    16474     +135     
  Branches       36       40       +4     
==========================================
+ Hits        14740    14804      +64     
- Misses       1592     1651      +59     
- Partials        7       19      +12     

Files	Coverage Δ
python/pydantic_core/core_schema.py	94.70% <100.00%> (-0.07%)	⬇️
src/errors/validation_exception.rs	92.87% <100.00%> (ø)
src/serializers/extra.rs	99.54% <100.00%> (+0.01%)	⬆️
src/serializers/infer.rs	95.14% <100.00%> (+0.02%)	⬆️
src/serializers/mod.rs	100.00% <100.00%> (ø)
src/validators/function.rs	94.35% <0.00%> (-3.25%)	⬇️
src/serializers/type_serializers/generator.rs	80.12% <0.00%> (-14.73%)	⬇️
src/serializers/type_serializers/function.rs	86.58% <17.64%> (-9.81%)	⬇️

... and 6 files with indirect coverage changes

---

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[codspeed-hq]

CodSpeed Performance Report

Merging #1215 will not alter performance

_{Comparing ornariece:serialization-context (617d086) with main (a98b8b0)}

Summary

✅ 148 untouched benchmarks

[ornariece]

CodSpeed Performance Report

Merging #1215 will degrade performances by 22.47%

Comparing ornariece:serialization-context (e1e6bc7) with main (a98b8b0)

Summary

❌ 2 regressions ✅ 146 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

Benchmark main ornariece:serialization-context Change
❌ test_core_future_str 31.8 µs 39.4 µs -19.38%
❌ test_core_future 29.2 µs 37.6 µs -22.47%

I think this is an artefact? Those tests only involve validation, and I only touched the serialization... or so I think.

[ornariece]

as for the pypy3.9 test failing, i honestly have too little experience with Rust to have a clue as to why

[ornariece]

please review

[davidhewitt]

Thanks! Overall this looks great, clean implementation given first use of Rust! Hopefully you enjoyed the experience of working with Rust & PyO3 :)

I just have a few small thoughts which would nice to tidy up...

[davidhewitt]

As context is arbitrary user contents which might end up creating a circular reference, it's probably a good idea to add a __traverse__ implementation so that the Python GC can see into these fields. (Probably we should have already done this with include / exclude, though with proper use circular references seem less likely for those.)

Would you be willing to help add this please?

https://pyo3.rs/v0.20.3/class/protocols#garbage-collector-integration

[ornariece]

latest commit should resolve this :)

[davidhewitt]

as for the pypy3.9 test failing, i honestly have too little experience with Rust to have a clue as to why

This is sadly just PyPy flakiness which nobody can get to the bottom of, see it all over this place in PyO3/pyo3#3766

[davidhewitt]

Looks great, thanks very much!

[ornariece]

awesome, thank you! i'm gonna submit a PR for pydantic now 👍

[ornariece]

the PR is ready, i'll wait until the new pydantic-core release to submit it to pydantic @davidhewitt

[davidhewitt]

It might be worth opening the PR anyway, even if it doesn't build yet, so that we can remember this needs to go into pydantic 2.7.