chore: apply small refactoring

[tottoto]

Applies small refactoring.

[charlespierce]

Nice, I really appreciate cleanups like this! A couple small comments to make sure the behavior is correct.

Separately, is there a way we can confirm the value that we're writing is parseable by httpdate? While the current approach is convoluted, it is making sure to compare apples to apples by using the Expires struct directly for the comparison.

It actually looks like the Expires header provides an implementation of From<Expires> for SystemTime, so we might be able access the time directly, rather than needing to parse the string value.

Another important piece is we want to make sure any comparison is backwards-compatible with the existing expiry file.

[charlespierce]

It looks like the Header::name associated function returns a &'static reference to the HeaderName object. Given that, we can probably use the same here (&'static HeaderName) instead of needing to convert it to an owned value.

[tottoto]

Updated to use &'static HeaderName.

[charlespierce]

It's definitely possible I'm misreading, but I believe this might be inverting the condition. In the current code, when SystemTime::now() < expiry_date, then we read the cached file. However, in this one we're returning no cache with that same condition.

[tottoto]

I would think the behavior would be the same as the code before this change as the negation of this condition is evaluated.

[tottoto]

Separately, is there a way we can confirm the value that we're writing is parseable by httpdate? While the current approach is convoluted, it is making sure to compare apples to apples by using the Expires struct directly for the comparison.

As headers::Expires and httpdate both support HTTP-date format defined in rfc7231, they are compatible.

It actually looks like the Expires header provides an implementation of From for SystemTime, so we might be able access the time directly, rather than needing to parse the string value.

Yes. When using Expires, it is possible to evaluate like this SystemTime::now() < expiry_date.into().

Another important piece is we want to make sure any comparison is backwards-compatible with the existing expiry file.

Since headers crate actually uses httpdate to parse and format date and delegate the comparison to internal httpdate implementation, and the httpdate uses SystemTime for its comparison, it behaves exactly the same.

[charlespierce]

LGTM, thanks!