Fixes #4466: CPU Usage performance metrics logging

[Sarthak2601]

Explanation

Fixes #4466: CPU Usage performance metrics logging.

Introduces a CpuPerformanceSnapshotter that leverages the abilities of an actor to sequentially log cpu usage. Cpu usage is logged after a certain delay which is calculated on the basis of current Iconification (foreground/background) of the app. This iconification is updated every time the app changes state, i.e. goes from foreground to background or vice-versa.

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• Any changes to scripts/assets files have their rationale included in the PR explanation.
• The PR follows the style guide.
• The PR does not contain any unnecessary code changes from Android Studio (reference).
• The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• The PR is assigned to the appropriate reviewers (reference).

[BenHenning]

Thanks @Sarthak2601. Sent my first batch of thoughts.

I think something else that would be really helpful here is including a detailed analysis in the opening comment demonstrating that this works as expected (e.g. by making the app simulate different types of loads on the system over different time periods to show that the computation is correct). I think we also need to make sure the solution works across multiple device images (which may require sharing a build with team members who have physical Android devices and can test the build in different configurations--you'll need to have a way to analyze the results).

I suspect the testing part can happen after this PR is merged (as part of verifying the dashboard changes), but we should at least verify it on a Google & non-Google physical device before merging.

[oppiabot]

Hi @Sarthak2601, I'm going to mark this PR as stale because it hasn't had any updates for 7 days. If no further activity occurs within 7 days, it will be automatically closed so that others can take up the issue.
If you are still working on this PR, please make a follow-up commit within 3 days (and submit it for review, if applicable). Please also let us know if you are stuck so we can help you!

[BenHenning]

Thanks @Sarthak2601. Took a high-level pass; there are some things I'm not sure that I fully understand conceptually so PTAL at the comments. It'd be helpful to resolve these, then I can another conceptual pass before you finish up the rest of the PR.

[BenHenning]

Thanks @Sarthak2601. Left some more thoughts, + some in chat (regarding availableProcessors() and potential downsides to using it).

[BenHenning]

Thanks @Sarthak2601! Just had a few comments (mostly nits and one functional clarification), but otherwise I think the tests look really good! The PR seems quite close to completion now.

[BenHenning]

Thanks @Sarthak2601! Overall, the PR looks fantastic. I just had a few small follow-up comments.

[BenHenning]

Thanks @Sarthak2601. Excellently done PR that completely LGTM. :)

[BenHenning]

Heads up that I think you'll need to sync to the latest develop branch before you can merge. Could you also update your latest require test to verify the exception message (since IllegalArgumentException is really generic)? No need to have me reapprove that specific change.

[oppiabot]

Hi @Sarthak2601, this PR is ready to be merged. Please address any remaining comments prior to merging, and feel free to merge this PR once the CI checks pass and you're happy with it. Thanks!

[Sarthak2601]

Heads up that I think you'll need to sync to the latest develop branch before you can merge. Could you also update your latest require test to verify the exception message (since IllegalArgumentException is really generic)? No need to have me reapprove that specific change.

Done with the change and synced to the latest develop.
Highly grateful for all the support @BenHenning!