fix(ffi): add methods to make QR login handlers exit cooperatively

[Johennes]

With my Filament hat on: This add new methods on the QR login handlers to make them exit cooperatively by first dropping the updates task and then returning. We've found this necessary when using the React Native FFI bindings in release builds to prevent crashes when the futures are cancelled.

• I've documented the public API changes in the appropriate changelog files (see Writing changelog entries).
• This PR was made with the help of AI.

[codecov]

Codecov Report

❌ Patch coverage is 93.91304% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.94%. Comparing base (374ed78) to head (0107945).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...atrix-sdk/src/authentication/oauth/qrcode/login.rs	91.42%	13 Missing and 2 partials ⚠️
...atrix-sdk/src/authentication/oauth/qrcode/grant.rs	95.01%	5 Missing and 8 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6677      +/-   ##
==========================================
+ Coverage   89.91%   89.94%   +0.03%     
==========================================
  Files         398      398              
  Lines      111154   111482     +328     
  Branches   111154   111482     +328     
==========================================
+ Hits        99948   100278     +330     
+ Misses       7415     7410       -5     
- Partials     3791     3794       +3     

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[codspeed-hq]

Merging this PR will not alter performance

✅ 50 untouched benchmarks

---

_{Comparing Johennes:johannes/cooperation (0107945) with main (374ed78)}

[Hywan]

Thanks for the contribution. I think it makes sense but I've added a couple comments.

Would it be possible to move that inside the matrix_sdk crate? First off, it would allow proper testing, and second, it can be useful for Rust users too. Keep in mind the FFI crate is only about bindings, no logic at all.

[Johennes]

Would it be possible to move that inside the matrix_sdk crate? First off, it would allow proper testing, and second, it can be useful for Rust users too. Keep in mind the FFI crate is only about bindings, no logic at all.

That would be great but I'm not entirely sure how. The problem only exists because of the progress tasks and those only exist in the FFI crate.

[Hywan]

The problem only exists because of the progress tasks and those only exist in the FFI crate.

Yes, but there is no interaction between the cancellation and the progress listener. I think it's a safe feature to move into matrix-sdk.

Or, alternatively (I don't want and I don't like this solution but I'm providing an alternative here), add tests in matrix-sdk-ffi for that. But please, consider moving this code (plus adding a test) in matrix-sdk first.

[Hywan]

One feedback unaddressed (about moving it to matrix-sdk).

[Johennes]

One feedback unaddressed (about moving it to matrix-sdk).

Yes, apologies. I'm still looking into that.

[Hywan]

No problem!

[Johennes]

Sorry for the long wait. I have moved the logic into the SDK in b731790. This is still missing tests in the granting case and updated changelog entries. But is this what you had in mind?

[Hywan]

Looks like it's the right direction.

[Johennes]

Somehow GitHub seems to have lost your comment about Notify vs. CancellationToken. I ran into ownership issues with Notify because it doesn't implement Clone. It's already used elsewhere in the project so I hoped it was ok to reuse here.

[Johennes]

Otherwise, this should finally be ready for review now.