...
use constant { ...
my $re = qr{ ...
open my $log_fh, '<', $logfile or die $!;

while my $log_line (<$log_fh>) {
    $log_line =~ /$re/;
    my ($date, @info) = @+{qw{date ACTION FAN_A FAN_B SEND FAILURE}};

    # do something with $date and @info here
}