Fixes for avoidance of hosts taking backup in PRS & ERS

[ejortegau]

Description

This PR addresses fixes issues in PRS & ERS preference for tablets that are not taking backups. It does away with redundant field definitions in some of the proto messages and addresses segfault that could take place during ERS.

Related Issue(s)

#17299
#16997

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

N/A

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 70.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 67.41%. Comparing base (ab7b516) to head (b9ae5a5).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vttablet/tabletmanager/rpc_replication.go	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17300      +/-   ##
==========================================
- Coverage   67.41%   67.41%   -0.01%     
==========================================
  Files        1576     1576              
  Lines      253417   253430      +13     
==========================================
+ Hits       170846   170851       +5     
- Misses      82571    82579       +8     

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[deepthi]

LGTM

[deepthi]

While these changes look good, the fact that the previous PR caused vtctld to crash points to missing tests.
Can you come up with a test case that would reproduce that particular crash and add it into this PR please?

Re-review

[deepthi]

While these changes look good, the fact that the previous PR caused vtctld to crash points to missing tests. Can you come up with a test case that would reproduce that particular crash and add it into this PR please?

I noticed that one of the commits says "fix SIGSEGV in test". Which test was that, and how was it passing on the previous PR?

[ejortegau]

While these changes look good, the fact that the previous PR caused vtctld to crash points to missing tests. Can you come up with a test case that would reproduce that particular crash and add it into this PR please?

I noticed that one of the commits says "fix SIGSEGV in test". Which test was that, and how was it passing on the previous PR?

The first PR accessed the flag indicating whether a backup was or not running directly from a field in a struct. The new code access it from a field in a pointer to the struct. Thus the previous PR always found something there (even if it was the default false), whereas the new one could get a nil struct and crash. Hence why that commit wrapped that in some checks for the struct pointer not being null.

[ejortegau]

While these changes look good, the fact that the previous PR caused vtctld to crash points to missing tests. Can you come up with a test case that would reproduce that particular crash and add it into this PR please?

The crash during ERS was a consequence of my first attempt to fix the fact that I was using the wrong value for figuring out whether the backup was running or not. By replacing this with this I introduced stopReplicationStatus.After.BackupRunning when After might be null. This didn't exist in the original PR and hence a corresponding test didn't exist or made no sense back then.

In any case, I just added some test cases to ensure that the value of the map with backup state information is correct, and to verify that if the After replication state is null, no segfault takes place and the value is taken from the before state.

[deepthi]

I don't see any new tests, maybe you forgot to push the new commit?

[ejortegau]

I don't see any new tests, maybe you forgot to push the new commit?

They should be visible now.