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Re: Selecting the "fastest" server listed in an array

by kyle (Abbot)
on Sep 11, 2007 at 01:40 UTC ( #638202=note: print w/replies, xml ) Need Help??


in reply to Selecting the "fastest" server listed in an array

This may work (I haven't tested it):

use Time::HiRes qw( ualarm tv_interval gettimeofday ); my $ua = LWP::UserAgent->new; my $fastest = undef; MIRROR: foreach my $mirror ( @mirrors ) { my $url = "$mirror/file.tar.bz2"; my $request = HTTP::Request->new(HEAD => $url); # if we have a possible fastest mirror, set an alarm ualarm( $fastest->{response_time} * 1_000_000 ) if defined $fastest; # attempt to fetch from this mirror in less time # than the fastest so far my ( $start_time, $response ); eval { local $SIG{ALRM} = sub { die 'alarm' }; $start_time = [gettimeofday]; $response = $ua->request($request); ualarm( 0 ); }; # if the alarm went off (or some other error), # try next mirror next MIRROR if $@; my $response_time = tv_interval( $start_time ); my $status = $response->status_line; # if this was successful, if ( $status == 200 ) { # if we haven't found a fast mirror yet, # or this one's faster, if ( ! defined $fastest || $fastest->{response_time} > $response_time ) { # store this one as the fastest $fastest = { mirror => $mirror, response_time => $response_time }; } } }

What's nice about this:

  • No forking.
  • If I've found a live site, I never wait for a dead one. In fact, I never wait for a site slower than the fastest one I've seen.
  • The $fastest that I find is a hash ref, so I can stash more info (such as the actual response) in there later, if I want.

I don't know how netselect works, so I can't speak to how well this works by comparison. I just hope to give you a good starting point.

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