use File::ReadBackwards;
use POSIX "strftime";

my $success;
my $items;
my $earliest = POSIX::strftime( "%Y-%m-%d %H:%M:%S", gmtime( time() - 30 * 60 ) );

$bw = File::ReadBackwards->new( 'log_file' ) or
                        die "can't read 'log_file' $!" ;
while ( defined( my $log_line = $bw->readline() ) ) {
    last if $log_line lt $earliest;

    $success ||= $log_line =~ /STATUS = SUCCESS/;
    $items ||= $log_line =~ /Found [1-9]\d* items to send/;

    last if $success && $items;
}