Fix SmoothingETA

[jonathanpoelen]

The value of smoothing_algorithm.update() was not used, therefore SmoothingETA was strictly identical to ETA.

I would like to take this opportunity to say that the constructor of SmoothingETA is particularly bad and incorrect in terms of typing:

    def __init__(
        self,
        smoothing_algorithm: type[
            algorithms.SmoothingAlgorithm
        ] = algorithms.ExponentialMovingAverage,
        smoothing_parameters: dict[str, float] | None = None,
        **kwargs,
    )

smoothing_parameters contradicts algorithms.SmoothingAlgorithm.__init__, which takes a dict[str, Any]. This typing also forces all inherited classes to use floats as parameters. This doesn't make sense. Furthermore, the constructor of algorithms.SmoothingAlgorithm throws an exception and forces you to create a __init__ function, even if it's not useful. algorithms.SmoothingAlgorithm shouldn't have a constructor.

The constructor of SmoothingETA should simply take an instance of algorithms.SmoothingAlgorithm and not have this horrible smoothing_parameters, which also makes IDE auto-completion unusable.

While I'm at it, what are the exponential_smoothing and exponential_smoothing_factor members and parameters of AdaptiveETA, since they are not used?

One last thing that's unrelated: time.time() is not monotonic, which creates bugs twice a year following daylight saving time changes or when there is an NTP synchronization that set back.

[gemini-code-assist]

Summary of Changes

Hello @jonathanpoelen, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical bug in the SmoothingETA widget where its smoothing functionality was not active due to an unassigned return value. By correctly capturing and using the smoothed value, this change ensures that SmoothingETA now functions as intended, providing more accurate and stable estimated times of arrival. The update also includes corresponding adjustments to test expectations and a minor documentation enhancement.

Highlights

• Core Bug Fix: Corrected an issue where SmoothingETA was effectively identical to ETA because the return value of smoothing_algorithm.update() was not being utilized. The fix now assigns the smoothed value back to value, ensuring the smoothing algorithm is actively applied.
• Documentation Update: Added SmoothingETA to the list of widgets in README.rst, improving documentation visibility.
• Test Updates: Updated expected ETA values in test_monitor_progress.py to reflect the correct behavior of SmoothingETA after the bug fix, showing the impact of the active smoothing.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a bug in SmoothingETA where the return value of smoothing_algorithm.update() was ignored, making the widget behave identically to ETA. The fix is correct and the tests have been updated accordingly.

Your analysis in the pull request description raises several excellent points about the library's design that are worth addressing:

1. SmoothingETA Constructor: Your suggestion to refactor the SmoothingETA constructor to accept an instantiated SmoothingAlgorithm object is a great idea. It would improve the API's flexibility and testability, following the Dependency Inversion Principle.
2. AdaptiveETA Unused Parameters: You are correct that exponential_smoothing and exponential_smoothing_factor in AdaptiveETA appear to be unused. This dead code should be removed.
3. Monotonic Time: Your point about time.time() not being monotonic is critical. For accurate duration calculations, the library should use time.monotonic() to avoid bugs related to system time adjustments.

These are valuable insights that would significantly improve the library. I recommend addressing them in separate, follow-up pull requests. This PR is good to merge as is for the immediate bug fix.

[wolph]

Very good catch! That does look like an improvement. I'm going to test it and get back to you.

With regards to monotonic, that would be a good idea indeed. I remember not using monotonic back when I wrote the code because it wasn't universally available, but I believe that's no longer the case so we can safely use it now.

The smoothing parameters is a legacy thing... I think I should just hide it with kwargs. It's basically meant to not break older code.