CNDB-7197: Added SAI_INDEX_METRICS_ENABLED to be able to enable/disable IndexMetrics

[ekaterinadimitrova2]

What is the issue

...
We want to be able to enable/disable IndexMetrics

What does this PR fix and why was it fixed

...
We add a flag to be able to do that - SAI_INDEX_METRICS_ENABLED("cassandra.sai.metrics.index.enabled", "true")
Also, added some simple unit tests to test the new parameter.

[github-actions]

Checklist before you submit for review

• This PR adheres to the Definition of Done
• Make sure there is a PR in the CNDB project updating the Converged Cassandra version
• Use NoSpamLogger for log lines that may appear frequently in the logs
• Verify test results on Butler
• Test coverage for new/modified code is > 80%
• Proper code formatting
• Proper title for each commit staring with the project-issue number, like CNDB-1234
• Each commit has a meaningful description
• Each commit is not very long and contains related changes
• Renames, moves and reformatting are in distinct commits
• All new files should contain the DataStax copyright header instead of the Apache License one

[adelapena]

There is a bunch of (probably harmless) dereferences like this one, and no external clue about IndexContext#getIndexMetrics being nullable. I think we could do that method return an Optional:

public Optional<IndexMetrics> getIndexMetrics()
{
    return Optional.ofNullable(indexMetrics);
}

and then use it this way:

Suggested change

	if (indexContext.getIndexMetrics() != null)
	indexContext.getIndexMetrics().segmentFlushErrors.inc();
	indexContext.getIndexMetrics().ifPresent(m -> m.segmentFlushErrors.inc());

[ekaterinadimitrova2]

Oh you are totally right. I was thinking about that and then forgot to fix it :( Thanks!

[pkolaczk]

+1

[adelapena]

We could use the inherited SAITester#assertMetricDoesNotExist. And since we have that method there, maybe we could move assertMetricExists to SAITester too?

[ekaterinadimitrova2]

CI finished ok, but Sonar complained about a missing test (one of the metrics never had a test, but because now we touched the code...), so I added that, removed a few imports I saw we don't need, and fixed one more warning from Sonar. That should be a wrap. @adelapena , @pkolaczk , please check the latest changes that you agree with everything. In the meantime I will update and run CI for the other PR.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
93.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cassci-bot]

❌ Build ds-cassandra-pr-gate/PR-2025 rejected by Butler

---

2 regressions found
See build details here

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Found 2 new test failures

Test	Explanation	Runs	Upstream
o.a.c.index.sai.cql.datamodels.QueryWriteLifecycleWithCompositePartitionKeyTest.testWriteLifecycle[ca]	<span title="The test is FAILING on feature but PASSING on upstream:
• Feature branch: FAILING in the recent 2 >= 2 minimum runs (1 actual failures, 1 missing/skipped) in 2 builds (1 to 3)
• Upstream branch: PASSING in the last 7 runs in 7 builds (1578 to 1587)">REGRESSION	🔴⚪	0 / 7
o.a.c.metrics.TopFrequencySamplerTest.testSamplerSingleInsertionsEqualMulti (compression)	<span title="The test is FLAKY on feature and PASSING on upstream:
• Feature branch: FLAKY because there are 1 passing, 1 failing, 0 missing, and 0 skipped runs in the last 2 runs in 2 builds (1 to 3)
• Upstream branch: PASSING in the last 7 runs in 7 builds (1578 to 1587)">REGRESSION	🔴🔵	0 / 7

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No known test failures found

[ekaterinadimitrova2]

testWriteLifecycle - known issue from #15218
testSamplerSingleInsertionsEqualMulti - it doesn't fail for me locally, and it doesn't seem related to me, so I suggest we open follow up ticket