8.5.0 includes breaking changes on the statistics object

[g3n35i5]

With v8.5.0, the statistics object moved from

wrapped_function.retry.statistics to wrapped_function.statistics.

This is a breaking change to the API and thus needs to be a major version update imo.

I'd suggest to add a fallback reference to the wrapped function in order to remove the breaking change.

[vijaysitaram]

Seeing something similar. Sanitized sample of our code:

    @tenacity.retry(
        retry=tenacity.retry_if_exception_type(MyCustomError),
        stop=tenacity.stop_after_attempt(MAX_ATTEMPTS),
    )
    def _internal():
        attempt_number = _internal.retry.statistics["attempt_number"]
        ...

now gives this during execution

KeyError: 'attempt_number'

[jd]

@hasier is this something we could avoid breaking or should I just bump to version 9?

[hasier]

I'd say it's difficult to keep that API, as per #484 we need a new retry instance each time the function is called to avoid overwriting the retry context on recursive calls, so that retry object cannot be used for statistics anymore. Unless y'all can think of a different approach, maybe this does deserve a major version bump. Sorry about that.

[g3n35i5]

@hasier no worries, this can happen :)

I'm totally fine with the API change, but as you said this should be a major version bump.

[vijaysitaram]

@hasier same, gotta do what you gotta do. We ended up working around it in our code by using the previous implementation if it exists or falling back to the newer one, e.g. from
attempt_number = _internal.retry.statistics["attempt_number"]
to
attempt_number = _internal.retry.statistics.get("attempt_number") or _internal.statistics.get("attempt_number")

[steve-marmalade]

@vijaysitaram thanks for the one-liner; this helped us quickly patch our application code.

I agree with others that this should be a major version bump; we just got hit with the same error (and it hits a rare enough code path that we didn't catch it in staging).