lock_guard<mutex> lock(mu);
auto type_it = types.cbegin();
for (const auto &key_and_metric : metrics) {
lock_guard<mutex> lock(mu);
auto type_it = types.cbegin();
for (const auto &key_and_metric : metrics) {
// It's the first time we print out any metric with this name,
// so add the type header.
if (type_it->second == TYPE_GAUGE) {
// It's the first time we print out any metric with this name,
// so add the type header.
if (type_it->second == TYPE_GAUGE) {