appender: add fallback to file creation date

[kaffarell]

When using the linux-musl target for rust, the file creation time cannot be retrieved, as the current version does not support it yet ( This will be fixed with ^0). In the meantime, we parse the datetime from the filename and use that as a fallback.

Fixes: #2999

[zerolfx]

You may need to handle the prefix and suffix before parsing the date (a reverse function of join_date).

https://github.com/tokio-rs/tracing/blob/c6bedbe2725830c1e78cbcdb9168de69c98e42fc/tracing-appender/src/rolling.rs#L551-L569

[kaffarell]

Oh, yeah, you're right. Thanks for the heads up, updated it now. Extracted the the datetime from the prefix/suffix, then converted to PrimitiveDateTime (because OffsetDateTime also takes a offset), then just assume it's utc (this is fine, because we also do this when writing AFAIK).

[zerolfx]

The prefix or suffix can also contain a dot.

[kaffarell]

Damn, forgot about that. Should work now!

[kaffarell]

Third time's the charm :) LMK what you think now!

[zerolfx]

replacen can occur within a string. We must ensure they are strictly prefixes or suffixes.

[kaffarell]

What do you mean exactly, could you paste an example? If the logfile prefix given is not actually the prefix in the filename, we will get a wrong date string and the parsing will fail, but this is intended.

[mladedav]

I think you could have suffix 2024 and then files like prefix-2024-01-01-2024 will get turned into -01-01-2024.

[kaffarell]

Oof, right. I could reverse the suffix and the whole filename string and then search through? Like that I would always get the first substring from behind. AFAIK rust doesn't have a function to make it more convention ...

[mladedav]

Wouldn't strip_prefix and strip_suffix work instead of replacen?

[bnjbvr]

Hi! what's the status of this PR? Looks like it addressed all the review comments, is it getting blocked for some reason? We'd love to have this fix to avoid using a fork of tracing that includes it, in a downstream project of ours :pray: Thanks for your work here!

[kaffarell]

@davidbarsky friendly ping :)

[cyt-666]

not work when rotation is set to Rotation::DAILY, PrimitiveDateTime::parse(datetime, &self.date_format) return None.

PrimitiveDateTime can not parse a str without time part.

let created:Option<SystemTime> = match self.rotation {
                    Rotation::DAILY => {
                        let day =Date::parse(datetime, &self.date_format).ok()?;
                        Some(PrimitiveDateTime::new(day, Time::MIDNIGHT).assume_utc().into())
                    },
                    _ => {
                        Some(PrimitiveDateTime::parse(datetime, &self.date_format)
                    .ok()?
                    .assume_utc().into())
                    }
                };