fix(rax_tree): Fix crash caused by destructor in RaxTreeMap

[BagritsevichStepan]

fixes #4172

The cause of the crash is double raxStop call: first time in the operator++ when raxNext returns false, second time in the destructor of the SeekIterator.

In this PR:

1. Remove double raxStop call
2. Fix bug when raxSeek returns 0 in the constructor
3. Wrap iterator to optional for more safety
4. Delete operator= for the SeekIterator
5. Fixed operator== for the FindIterator. We had some strange logic there: if (this->has_value() != !bool(rhs.it_.flags & RAX_ITER_EOF))
6. Add dcheks and logging for more safety

I also propose to change destructor of the RaxTreeMap. It should invoke raxFreeWithCallback. The problem is that this will require a capturing lambda, as we need to pass alloc_. Therefore, we need to copy and update the raxFreeWithCallback method for capturing lambdas.

[BagritsevichStepan]

https://github.com/dragonflydb/dragonfly/actions/runs/12082557873

[romange]

Can you please explain what the problem is in the PR description?
i.e. the cause of crash is ..., this solution solves the problem by .... , but i suggest the following solution ...

[BagritsevichStepan]

Can you please explain what the problem is in the PR description? i.e. the cause of crash is ..., this solution solves the problem by .... , but i suggest the following solution ...

Done

[BagritsevichStepan]

@kostasrim Run it again: https://github.com/dragonflydb/dragonfly/actions/runs/12140115454

[romange]

@BagritsevichStepan I agree that the interface of raxFreeWithCallback should be changed by accepting an additional void* arg argument that is passed by raxFreeWithCallback to each invocation of free_callback

[BagritsevichStepan]

@romange I decided to introduce Callback calling in the another PR #4255. I'm not sure if we should merge this before the release

[romange]

LGTM

[romange]

have you run on the traces you have to see it's working well?

[BagritsevichStepan]

have you run on the traces you have to see it's working well?

Yes, https://github.com/dragonflydb/dragonfly/actions/runs/12162671806