Preserve a log file's modification time on rotation

[spinitron]

What steps will reproduce the problem?

Use Yii's FileTarget enough to cause log file rotation.

What is the expected result?

FS modification time of each log file indicates the date-time when that log file was last written.

What do you get instead?

It indicates when the file was last copied in a rotation.

It is likely enough to add one line to the FileTarget::rotateByCopy() function

        @touch($newFile, filemtime($rotateFile));

[samdark]

Is there a big difference? Why does it matter?

[rob006]

Why do we even use copy() for older logs. Renaming active log file could be problematic, but it should be safe for older log files.

[spinitron]

Is there a big difference?

Difference can be big. Say you have a log that rotates approx. every month and you keep 5. If when you go to look at the logs the rotation happened an hour ago, all 5 files have an mtime of one hour ago.

Why does it matter?

It matters because the correct mtime tells you when a file was last written. So if you want to look at logs surrounding a given timestamp, you can choose the file to look at from ls -l without needing to examine the files themselves.

[spinitron]

Why do we even use copy() for older logs. Renaming active log file could be problematic, but it should be safe for older log files.

Good question. I guess it's because the code to copy the active file and rename the older ones would be more complex and nobody got around to writing it.

[spinitron]

I can code this but I have no idea how to write the tests for it.

[samdark]

Yeah. Time-based tests that include file system are tricky.

[handcode]

Why do we even use copy()

JFTR: The option to use rotateByRename has been removed here: #19259

[samdark]

@spinitron is the issue still valid considering copy() was removed?

[rob006]

@samdark copy() usage was not removed, it is enforced since #19259

[samdark]

Right!