]> git.sesse.net Git - nageru/blobdiff - metrics.cpp
Update the queue length metric after trimming, not before.
[nageru] / metrics.cpp
index fd5e54c1c7f48b09d38f64ddd91d84bee4a3b6c0..5079acb2064e5515a1a549af00c35924edcc57dd 100644 (file)
@@ -18,12 +18,15 @@ double get_timestamp_for_metrics()
        return duration<double>(system_clock::now().time_since_epoch()).count();
 }
 
-namespace {
+string Metrics::serialize_name(const string &name, const vector<pair<string, string>> &labels)
+{
+       return "nageru_" + name + serialize_labels(labels);
+}
 
-string serialize_name(const string &name, const vector<pair<string, string>> &labels)
+string Metrics::serialize_labels(const vector<pair<string, string>> &labels)
 {
        if (labels.empty()) {
-               return "nageru_" + name;
+               return "";
        }
 
        string label_str;
@@ -33,21 +36,17 @@ string serialize_name(const string &name, const vector<pair<string, string>> &la
                }
                label_str += label.first + "=\"" + label.second + "\"";
        }
-       return "nageru_" + name + "{" + label_str + "}";
+       return "{" + label_str + "}";
 }
 
-}  // namespace
-
 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, atomic<int64_t> *location, Metrics::Type type)
 {
        Metric metric;
        metric.data_type = DATA_TYPE_INT64;
-       metric.name = name;
-       metric.labels = labels;
        metric.location_int64 = location;
 
        lock_guard<mutex> lock(mu);
-       metrics.push_back(metric);
+       metrics.emplace(MetricKey(name, labels), metric);
        assert(types.count(name) == 0 || types[name] == type);
        types[name] = type;
 }
@@ -56,30 +55,43 @@ void Metrics::add(const string &name, const vector<pair<string, string>> &labels
 {
        Metric metric;
        metric.data_type = DATA_TYPE_DOUBLE;
-       metric.name = name;
-       metric.labels = labels;
        metric.location_double = location;
 
        lock_guard<mutex> lock(mu);
-       metrics.push_back(metric);
+       metrics.emplace(MetricKey(name, labels), metric);
        assert(types.count(name) == 0 || types[name] == type);
        types[name] = type;
 }
 
-void Metrics::add(const string &name, const vector<pair<string, string>> &labels, Histogram *location)
+void Metrics::add(const string &name, const vector<pair<string, string>> &labels, Histogram *location, Laziness laziness)
 {
        Metric metric;
        metric.data_type = DATA_TYPE_HISTOGRAM;
-       metric.name = name;
-       metric.labels = labels;
+       metric.laziness = laziness;
        metric.location_histogram = location;
 
        lock_guard<mutex> lock(mu);
-       metrics.push_back(metric);
+       metrics.emplace(MetricKey(name, labels), metric);
        assert(types.count(name) == 0 || types[name] == TYPE_HISTOGRAM);
        types[name] = TYPE_HISTOGRAM;
 }
 
+void Metrics::remove(const string &name, const vector<pair<string, string>> &labels)
+{
+       lock_guard<mutex> lock(mu);
+
+       auto it = metrics.find(MetricKey(name, labels));
+       assert(it != metrics.end());
+
+       // If this is the last metric with this name, remove the type as well.
+       if (!((it != metrics.begin() && prev(it)->first.name == name) ||
+             (it != metrics.end() && next(it)->first.name == name))) {
+               types.erase(name);
+       }
+
+       metrics.erase(it);
+}
+
 string Metrics::serialize() const
 {
        stringstream ss;
@@ -87,22 +99,35 @@ string Metrics::serialize() const
        ss.precision(20);
 
        lock_guard<mutex> lock(mu);
-       for (const auto &name_and_type : types) {
-               if (name_and_type.second == TYPE_GAUGE) {
-                       ss << "# TYPE nageru_" << name_and_type.first << " gauge\n";
-               } else if (name_and_type.second == TYPE_HISTOGRAM) {
-                       ss << "# TYPE nageru_" << name_and_type.first << " histogram\n";
+       auto type_it = types.cbegin();
+       for (const auto &key_and_metric : metrics) {
+               string name = "nageru_" + key_and_metric.first.name + key_and_metric.first.serialized_labels;
+               const Metric &metric = key_and_metric.second;
+
+               if (type_it != types.cend() &&
+                   key_and_metric.first.name == type_it->first) {
+                       // It's the first time we print out any metric with this name,
+                       // so add the type header.
+                       if (type_it->second == TYPE_GAUGE) {
+                               ss << "# TYPE nageru_" << type_it->first << " gauge\n";
+                       } else if (type_it->second == TYPE_HISTOGRAM) {
+                               ss << "# TYPE nageru_" << type_it->first << " histogram\n";
+                       }
+                       ++type_it;
                }
-       }
-       for (const Metric &metric : metrics) {
-               string name = serialize_name(metric.name, metric.labels);
 
                if (metric.data_type == DATA_TYPE_INT64) {
                        ss << name << " " << metric.location_int64->load() << "\n";
                } else if (metric.data_type == DATA_TYPE_DOUBLE) {
-                       ss << name << " " << metric.location_double->load() << "\n";
+                       double val = metric.location_double->load();
+                       if (isnan(val)) {
+                               // Prometheus can't handle “-nan”.
+                               ss << name << " NaN\n";
+                       } else {
+                               ss << name << " " << val << "\n";
+                       }
                } else {
-                       ss << metric.location_histogram->serialize(metric.name, metric.labels);
+                       ss << metric.location_histogram->serialize(metric.laziness, key_and_metric.first.name, key_and_metric.first.labels);
                }
        }
 
@@ -151,8 +176,22 @@ void Histogram::count_event(double val)
        sum = sum + val;
 }
 
-string Histogram::serialize(const string &name, const vector<pair<string, string>> &labels) const
+string Histogram::serialize(Metrics::Laziness laziness, const string &name, const vector<pair<string, string>> &labels) const
 {
+       // Check if the histogram is empty and should not be serialized.
+       if (laziness == Metrics::PRINT_WHEN_NONEMPTY && count_after_last_bucket.load() == 0) {
+               bool empty = true;
+               for (size_t bucket_idx = 0; bucket_idx < num_buckets; ++bucket_idx) {
+                       if (buckets[bucket_idx].count.load() != 0) {
+                               empty = false;
+                               break;
+                       }
+               }
+               if (empty) {
+                       return "";
+               }
+       }
+
        stringstream ss;
        ss.imbue(locale("C"));
        ss.precision(20);
@@ -167,13 +206,13 @@ string Histogram::serialize(const string &name, const vector<pair<string, string
                bucket_labels.emplace_back("le", le_ss.str());
 
                count += buckets[bucket_idx].count.load();
-               ss << serialize_name(name + "_bucket", bucket_labels) << " " << count << "\n";
+               ss << Metrics::serialize_name(name + "_bucket", bucket_labels) << " " << count << "\n";
        }
 
        count += count_after_last_bucket.load();
 
-       ss << serialize_name(name + "_sum", labels) << " " << sum.load() << "\n";
-       ss << serialize_name(name + "_count", labels) << " " << count << "\n";
+       ss << Metrics::serialize_name(name + "_sum", labels) << " " << sum.load() << "\n";
+       ss << Metrics::serialize_name(name + "_count", labels) << " " << count << "\n";
 
        return ss.str();
 }