fix clock bankhash mismatch

[jackcmay]

Problem

Deprecating segment from the clock sysval broke bankhash

Summary of Changes

Continue to calculate the correct values

follow-up to: #9992

[jackcmay]

@ryoqun fyi

[codecov]

Codecov Report

Merging #10078 into master will decrease coverage by 0.1%.
The diff coverage is 100.0%.

@@            Coverage Diff            @@
##           master   #10078     +/-   ##
=========================================
- Coverage    81.5%    81.4%   -0.2%     
=========================================
  Files         283      283             
  Lines       65797    65827     +30     
=========================================
- Hits        53659    53611     -48     
- Misses      12138    12216     +78     

[ryoqun]

Cool!!! So, we can just avoid a rather costly transition entirely. :)

Could you manually test this actually fixes vote mismatch errors according to these steps?: #9992 (comment)

[ryoqun]

And extra bonus is that this pr could contain a bank_hash deterministic test like this if you have extra bandwidth :) :

test_bank_hash() {
    genesis_bank = ... # some deterministic way with warm-up epoch
    next_bank = Bank::new_from_parent(genesis_bank)
    assert_eq!(genesis_bank.hash(), "81KbyqL4FmPEwLxdg4...........")
    # fast forward to next epoch
    while/loop/whatever {
      bank = new_from_parent(bank)
    }
    ....
    assert_eq!(bank_in_next_epoch.bank_hash(), "4Q8t8qk4qqAjiqs..........");
}

Which is actually on my due. ;)

[jackcmay]

Yup, I did verify it via those steps, thanks for the good writeup. I'll look into a representative test

[jackcmay]

@ryoqun how about this test? I ran it across different scenarios (with the owner in the hash, without, with my archiver's removed w and w/o this PR) and it looks like it accomplishes what we need. Let me know what you think.

[ryoqun]

perfect! That's what I'm looking for. :)

[ryoqun]

nits: why we stop at slot 4? I mean, why not 3 or 5? Is there specific reason? Some slots just to be safe? one line comment or const SOME_SLOT = 4; would be useful for future maintenance.

[jackcmay]

Just check some slots, I modified it to cross a epoch boundary

[ryoqun]

Thanks for working on this, even with tests. :)

Pull request has been modified.

[ryoqun]

LGTM!