[logutil]: Fix MaxDays and MaxBackups not working for slow-query-logger

[SabaPing]

What problem does this PR solve?

Fix MaxDays and MaxBackups not working for slow-query-logger

Issue Number: #25716

Problem Summary:

MaxDays and MaxBackups not working for slow-query-logger. This may causes unexpected disk usage.

What is changed and how it works?

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Manual test steps

Test MaxDays:

1. Create a directory named slowlog.
2. Create a file named slowlog-2021-11-01T23-00-00.001
3. Start TiDB with following config:

   [log.file]
   max-days = 1
   enable-slow-log = true
   slow-query-file = "PATH_TO_SLOWLOG_DIRECTORY/slowlog"

4. One should observe previously created file slowlog-2021-11-01T23-00-00.001 got deleted.

Test MaxBackups:

1. Create a directory named slowlog.
2. Create two files named slowlog-2021-11-01T23-00-00.001 and slowlog-2021-11-02T23-00-00.001.
3. Start TiDB with following config:

   [log.file]
   max-backups = 1
   enable-slow-log = true
   slow-query-file = "PATH_TO_SLOWLOG_DIRECTORY/slowlog"

4. One should observe previously created file slowlog-2021-11-01T23-00-00.001 got deleted.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix `MaxDays` and `MaxBackups` not working for slow log.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• qw4990
• wjhuang2016

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[crazycs520]

@bb7133 PTAL

[SabaPing]

/run-check_dev_2

[bb7133]

Hi @SabaPing did you verified the change locally?

[bb7133]

Please provide a 'manual test' in the PR description, thanks!

[jyz0309]

/run-check_dev_2

[jyz0309]

I have tested it, /cc @bb7133

[jyz0309]

/run-check_dev_2

[wjhuang2016]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 9667580

[jyz0309]

/run-check_dev_2

[ti-srebot]

cherry pick to release-5.2 in PR #29921

[YuJuncen]

/run-cherry-picker

[ti-srebot]

cherry pick to release-5.1 in PR #30171

[ti-srebot]

cherry pick to release-5.3 in PR #30172