[FLINK-24409][connectors] Fix metrics errors with topics names with periods

[jherico]

What is the purpose of the change

• Fix the errors generated by the metrics code when reading from a Kafka topic that includes periods in the names. The filter for the metric tries to compare the topic name against the corresponding metric topic tag, but the metric tags execute a transform on the topic name that replaces any periods with underscores, so if you try to find the records-lag metric in via the changed function, it logs a WARN level log with an exception stack trace.

Brief change log

• Execute the required transformation in the getRecordsLagMetric function

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Unfortunately while some of the tests in KafkaSourceReaderTest cover this code and changing the topic name in that class to "Kafka.Source.Reader.Test" even causes the issue, it doesn't actually cause the tests to fail. Further, the KafkaSourceReaderMetricsTest doesn't have any coverage of the getRecordsLagMetric function at all, which is disappointing. I tried to add some coverage but I wasn't successful.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

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Automated Checks

Last check on commit fd01adb (Fri Oct 01 06:35:44 UTC 2021)

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[AHeise]

@PatrickRen could you PTAL? I think we should have a test case for record lag metric as well.

[PatrickRen]

Thanks @jherico for the patch! This looks good to me. As suggested by @AHeise I think adding a case for testing topic names with period would be better.

[AHeise]

@PatrickRen could you please give pointers to @jherico on how to approach the test?

[PatrickRen]

Sorry for my late response! @jherico Here's my implementation of the test case that might be helpful. Feel free to cherry-pick it or implement your own.

PatrickRen@7e7f0d4

Another choice is to use parameterized test in JUnit 5 for testing pendingRecords with different topic names including with special characters, but first you need to migrate KafkaPartitionSplitReaderTest to JUnit 5 style. Here's my implementation:

PatrickRen@e17ac77

[MartijnVisser]

@jherico Do you think you could add the tests or do you need some more help?

[jherico]

I can most likely add some tests, I've just been very busy lately and it hasn't been a priority. Will try to see if I can manage in the next week or so.

…

On Wed, Nov 10, 2021 at 3:58 AM MartijnVisser ***@***.***> wrote: @jherico <https://github.com/jherico> Do you think you could add the tests or do you need some more help? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#17401 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AALWNSSFRJKQ5RYJ6WJPFUDULJM5PANCNFSM5FD6JTWQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[MartijnVisser]

That would be great. There are multiple contributors who would like to help out (it's a bug that we would like to resolve asap) so do let know in case you need any help.

[AHeise]

Does it make sense to re-assign the task to someone else?

[jherico]

ok, it's a pretty small change I know, but I'm kind of irked that #17773 appears to include my exact changes but without my actual commit.

[fapaul]

@jherico sorry that was my fault :( I did not think about when copying your code instead of cherry-picking the commit.