Straggler handling Follow-up

[ishant162]

This pull request is a follow-up to the Straggler Handling PR #996 . Based on the feedback from @MasterSkepticista and @teoparvanov , the review comments have been addressed and incorporated accordingly.

Summary of changes:

• Relocated straggler_handling to the openfl/component/aggregator directory.

• Consolidated all policies into openfl/component/aggregator/straggler_handling.py

• Renamed CutoffTimeBasedStragglerHandling to CutoffTimePolicy and PercentageBasedStragglerHandling to PercentagePolicy

• Removed the attribute deletion functionality from CutoffTimePolicy

• Validate OpenFL Security through regression testing

[teoparvanov]

@ishant162 , did you test for regression by raising a PR in OpenFL-Security?

[scngupta-dsp]

@ishant162 , did you test for regression by raising a PR in OpenFL-Security?

This needs to be done @teoparvanov . We will feedback once it is done

[MasterSkepticista]

This is a good improvement over the previous layout.

Most suggestions, though seem like nitpicks, have measurable changes on developers and users in the look-and-feel of the framework. Please take a look.

[ishant162]

@MasterSkepticista, @teoparvanov: With the regression checks on the openfl-security repository (PR: 657) successfully completed , this PR is now ready for review / merge

@psfoley: Based on inputs received during the review, Straggler handling policies have been renamed for ease of use and improved readability

• CutoffTimeBasedStragglerHandling to CutoffTimePolicy and
• PercentageBasedStragglerHandling to PercentagePolicy

Due to this existing users of Straggler Handling functionality may need to do following minor updates to plan.yaml. For e.g.

Current

straggler_handling_policy :
template : openfl.component.straggler_handling_functions.PercentageBasedStragglerHandling
settings :
percent_collaborators_needed : 0.5
minimum_reporting : 1

Updated

straggler_handling_policy :
template : openfl.component.aggregator.straggler_handling.PercentagePolicy
settings :
percent_collaborators_needed : 0.5
minimum_reporting : 1

To assist users in migration this aspect needs to be mentioned in release notes as a guide to users migrating to OpenFL v1.8

[teoparvanov]

Nice work, thanks @ishant162 ! I just have a couple of minor comments: