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Postings from January 2006
Greetings fellow Perl hackers, I'm attracted to DateTime's very comprehensive approach at dealing with time (which I personally consider to be one of the biggest annoyances and challenges in programming). Unfortunately, I've been plagued by an oddity in the way DateTime handles leap seconds in face of the Olson timezone database for some time. This shows up as test failures: t/04epoch...............NOK 12# Failed test (t/04epoch.t at line 40) # got: '997120978' # expected: '997121000' t/04epoch...............NOK 14# Failed test (t/04epoch.t at line 43) # got: '2' # expected: '3' t/04epoch...............NOK 20# Failed test (t/04epoch.t at line 81) # got: '1049160580' # expected: '1049160602' t/04epoch...............NOK 22# Failed test (t/04epoch.t at line 84) # got: '29' # expected: '30' t/04epoch...............NOK 24# Failed test (t/04epoch.t at line 90) # got: '1049167780' # expected: '1049167802' t/04epoch...............ok 32/32# Looks like you failed 5 tests of 32. t/04epoch...............dubious This happens when /etc/localtime is linked to a timezone in /usr/share/zoneinfo/right as opposed to /usr/share/zoneinfo. The problem bites me in the ass, unfortunately, because I tend to store date / time values in SQL as an epoch rather than a native type (less back and forth conversion required). This can result in my events drifting 22 seconds, etc. Also, it's been clear to me that using DateTime heavily is a good way to quickly kill performance. Pages that took 20ms to render jump to 500ms when I try to do something "simple" like apply a recurrence set to a month. I started peering into DateTime internals and have noticed that the xs seems a little... lite? Curiously, I read the text supplied with the distribution and noticed this: NOTE TO FUTURE DEVELOPERS: Attempting to implement add_duration in XS actually seemed to slow date math operations down. Sad but true. Curious - what was the strategy? What do you assume to be the bottleneck? C has *got* to be faster at math than Perl, so I have a feeling the above remark is specific to a particular implementation approach. Along those lines, are there any known outstanding areas where DateTime could use some optimization? I'm handy with C, very handy with Perl and somewhat capable with XS... I'd like to help. Thanks, Chase VentersThread Next