1046213 - datetime_from() generates wrong dates if year < 1901

Status: RESOLVED FIXED

(Bugzilla :: Bugzilla-General, defect)

Description

[Frédéric Buclin]

Attachment: patch, v1

While investigating why datetime_from("1900-12-31") takes 5.74 seconds on my machine and datetime_from("1901-01-01") takes 0.10 second, I realized that datetime_from() was passing incorrect data to DateTime->new() if the date was older than 1901 (which can happen as we have date and datetime custom fields). That's because strptime() returns the full year if older than 1901. So datetime_from() was incorrectly converting year 1900 into year 3800, making DateTime() terribly slow.

Comment 1

[Simon Green]

Given that Date::Parse (which uses Date::Local) is known to be buggy (see https://metacpan.org/pod/Date::Parse#LIMITATION), wouldn't a better solution to be using something like DateTime::Format::Strptime ( https://metacpan.org/pod/DateTime::Format::Strptime ), especially considering we turn it into a DateTime object anyway?

Comment 2

[Frédéric Buclin]

(In reply to sgreen from comment #1)

That's an idea, but the problem is that DateTime::Format::Strptime::new() requires the pattern to be provided, i.e. you must know which format is used for the input datetime string, while Date::Parse::strptime() runs several regexps to guess which format is used. As datetime_from() is called from many places, it's hard to determine the pattern for sure, unless we run our own regexps first.

Comment 3

[Frédéric Buclin]

To ssh://[e-mail]/bugzilla/bugzilla.git
   ace2e1a..fc4350a  master -> master

To ssh://[e-mail]/bugzilla/bugzilla.git
   e74616b..76b3203  4.4 -> 4.4