On Sat, November 22, 2008 12:50 am, Daisuke Maki wrote:
> So I have this requirement to make DateTime leaner, in terms of speed,
> load time, and the amount of memory consumed. The target is for casual
> users, so the use of XS code is not an option either.
In terms of speed, one of the things that's unique (AFAIK) to
DateTime is being able to thread-safely convert a datetime from
one timezone to another.
I'd be curious to know how it fares in this regard. Here's a
benchmark that for me shows DateTime proper almost ten times as
slow as non-thread-safely using libc routines (suggestions for
improvement enthusiastically welcomed):
#!/usr/bin/perl -l
use strict;
use warnings;
use DateTime;
use Env::C;
use POSIX "mktime";
sub convert_timezone_datetime {
my ($y,$mo,$d,$h,$m,$s,$tz,$new_tz) = @_;
my $dt = DateTime->new(year=>$y, month=>$mo, day=>$d, hour=>$h,
minute=>$m, second=>$s,time_zone=>$tz);
$dt->set_time_zone($new_tz);
return map $dt->$_, qw/year month day hour minute second/;
}
sub convert_timezone_env_c {
my ($y,$mo,$d,$h,$m,$s,$tz,$new_tz) = @_;
my $save_tz = Env::C::getenv("TZ");
Env::C::setenv("TZ",$tz,1);
my $time = POSIX::mktime($s,$m,$h,$d,$mo-1,$y-1900,0,0,-1);
Env::C::setenv("TZ",$new_tz,1);
POSIX::tzset(); # localtime_r bug
($s,$m,$h,$d,$mo,$y) = localtime($time);
$mo++; $y+=1900;
# this belongs in a destructor
if (defined $save_tz) { Env::C::setenv("TZ",$save_tz,1) }
else { Env::C::unsetenv("TZ") }
return ($y,$mo,$d,$h,$m,$s);
}
sub convert_timezone_system {
my ($y,$mo,$d,$h,$m,$s,$tz,$new_tz) = @_;
local $ENV{"TZ"} = $tz;
my $time = POSIX::mktime($s,$m,$h,$d,$mo-1,$y-1900,0,0,-1);
$ENV{"TZ"} = $new_tz;
POSIX::tzset(); # localtime_r bug
($s,$m,$h,$d,$mo,$y) = localtime($time);
$mo++; $y+=1900;
return ($y,$mo,$d,$h,$m,$s);
}
print join ",",
datetime=>convert_timezone_datetime(2008,7,3,23,2,3,"America/Denver","America/New_York");
print join ",",
registry=>convert_timezone_env_c(2008,7,3,23,2,3,"America/Denver","America/New_York");
print join ",",
"system"=>convert_timezone_system(2008,7,3,23,2,3,"America/Denver","America/New_York");
use Benchmark "timethese";
timethese(-5, {
datetime => sub { my ($y,$mo,$d,$h,$m,$s) =
convert_timezone_datetime(2008,7,3,23,2,3,"America/Denver","America/New_York");
return },
env_c => sub { my ($y,$mo,$d,$h,$m,$s) =
convert_timezone_env_c(2008,7,3,23,2,3,"America/Denver","America/New_York");
return },
"system" => sub { my ($y,$mo,$d,$h,$m,$s) =
convert_timezone_system(2008,7,3,23,2,3,"America/Denver","America/New_York");
return },
} );
