Attempt to encode the formatted log value given it's destination...

gistfile1.pl

has dest => "file";

sub format {
    my ($self, $level, @lines) = @_;
    my $txt = '[' . localtime(time) . "] [$level] " . join("\n", @lines, '');
    return "file" eq $self->dest ? encode('UTF-8', $txt) : $txt;
}

# ...

sub _message {
  my ($self, $level) = (shift, shift);

  return unless $self->is_level($level) && (my $handle = $self->handle);

  my $max     = $self->max_history_size;
  my $history = $self->history;
  $self->dest("history");
  push @$history, $self->format($level, @_);
  $self->dest("file");
  shift @$history while @$history > $max;

  flock $handle, LOCK_EX;
  $handle->print($self->format($level, @_)) or croak "Can't write to log: $!";
  flock $handle, LOCK_UN;
}