# Make a copy of a complex data structure that is thread-shared.
# If not thread sharing, then make a 'regular' copy.
sub shared_copy
{
    my $in = $_[0];

    # Make copies of array, hash and scalar refs
    if (my $ref_type = ref($in)) {
        # Copy an array ref
        if ($ref_type eq 'ARRAY') {
            # Make empty shared array ref
            my $out = ($threads::shared::threads_shared)
                            ? &threads::shared::share([])
                            : [];
            # Recursively copy and add contents
            for my $val (@$in) {
                push(@$out, shared_copy($val));
            }
            return ($out);
        }

        # Copy a hash ref
        if ($ref_type eq 'HASH') {
            # Make empty shared hash ref
            my $out = ($threads::shared::threads_shared)
                            ? &threads::shared::share({})
                            : {};
            # Recursively copy and add contents
            while (my ($key, $val) = each(%$in)) {
                $out->{$key} = shared_copy($val);
            }
            return ($out);
        }

        # Copy a scalar ref
        if ($ref_type eq 'SCALAR') {
            if ($threads::shared::threads_shared) {
                return (threads::shared::share($in));
            }
            # If not sharing, then make a copy of the scalar ref
            my $out = \do{ my $scalar; };
            $$out = $$in;
            return ($out);
        }
    }

    # Just return anything else
    # NOTE: This will generate an error if we're thread-sharing,
    #       and $in is not an ordinary scalar.
    return ($in);
}