change(chain): Refactor the handling of height differences

[upbqdn]

Motivation

Close #6279.

Solution

This PR handles height differences similarly to chrono::DateTime and chrono::Duration.

Reviewer Checklist

• Will the PR name make sense to users?
  • Does it need extra CHANGELOG info? (new features, breaking changes, large changes)
• Are the PR labels correct?
• Does the code do what the ticket and PR says?
  • Does it change concurrent code, unsafe code, or consensus rules?
• How do you know it works? Does it have tests?

[codecov]

Codecov Report

Merging #6330 (3238412) into main (e982a43) will increase coverage by 0.05%.
The diff coverage is 88.09%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6330      +/-   ##
==========================================
+ Coverage   77.69%   77.74%   +0.05%     
==========================================
  Files         304      304              
  Lines       39585    39639      +54     
==========================================
+ Hits        30756    30818      +62     
+ Misses       8829     8821       -8     

[upbqdn]

Tests for GBT RPCs are failing. I forgot to run them locally. I'm working on that.

[upbqdn]

Tests for GBT RPCs are failing. I forgot to run them locally. I'm working on that.

Fixed.

[arya2]

This looks excellent!

Feel free to ignore the couple trivial suggestions.

[mpguerra]

@upbqdn is going to be out for this week. Do we want to do anything with this PR in the meantime or should it wait until he gets back?

[teor2345]

@upbqdn is going to be out for this week. Do we want to do anything with this PR in the meantime or should it wait until he gets back?

@arya2 and I have enough context to finish it off, the remaining comments are mainly tweaks. I think it would be good to finish it to avoid merge conflicts with other work.

[teor2345]

It turns out if we make HeightDiff an i64, a whole lot of expect(), as, and other tricky interim checks go away. See a765be4 & 7ac8b89.

(We still have to check at the end of each calculation.)

[teor2345]

@arya2 this is ready for a re-review, the changes were a bit more substantial than I thought, but they helped remove a lot of code that's tricky to review.

I can do a video review if that would help?

[arya2]

This looks great!

I left a couple optional suggestions, feel free to ignore either or both of them.