I'm using DateTime::Set to encode a radio station's program lineup.
It's about 170 weekly recurrences that are all mostly about an hour
apart. If I try to find the current event it's really slow and I get a
pile of warnings from Set::Infinite. I can get the warnings to go away
if I set $Set::Infinite::max_backtrack_depth to 52. I can get
semi-reasonable performance for the ->current call if I restrict the
set being queried to only the recent past.
The warning:
Set::Infinite: Backtrack too deep (more than 10 levels) at
/home/josh/bin/perl/5.8.8/lib/site_perl/5.8.8/DateTime/Set.pm line 535
I'm hoping someone here can suggest a better way to do this, get
better performance from the ->current query, avoid having to manually
guess the range I'll find an answer in, and what's the deal with the
warnings.
# Look up whatever is current for a date/time.
$THE_DATE = ...
$all_events = DateTime::Set->empty_set->set_time_zone( 'US/Central' )
for ( ... )
$all_events = $all_events->union(
DateTime::Event::Recurrence
->weekly( %$_ )
->set_time_zone( 'US/Central' )
)
local $Set::Infinite::max_backtrack_depth = 52 # Set::Infinite, shut up!
# Restrict $all_events to only the recent past because this makes
the query faster
$recent_past = $all_events->intersection(
DateTime::Span->from_datetimes(
from => $THE_DATE->clone->subtract( hours => 4 )->truncate(
to => 'hour' ),
end => $THE_DATE
)
)
$CURRENT = $recent_past->current( $THE_DATE )
Josh
