git.sesse.net Git - nageru/blob - metrics.cpp

   1 #include "metrics.h"
   2
   3 #include <assert.h>
   4 #include <math.h>
   5
   6 #include <algorithm>
   7 #include <chrono>
   8 #include <locale>
   9 #include <sstream>
  10
  11 using namespace std;
  12 using namespace std::chrono;
  13
  14 Metrics global_metrics;
  15
  16 double get_timestamp_for_metrics()
  17 {
  18         return duration<double>(system_clock::now().time_since_epoch()).count();
  19 }
  20
  21 string Metrics::serialize_name(const string &name, const vector<pair<string, string>> &labels)
  22 {
  23         return "nageru_" + name + serialize_labels(labels);
  24 }
  25
  26 string Metrics::serialize_labels(const vector<pair<string, string>> &labels)
  27 {
  28         if (labels.empty()) {
  29                 return "";
  30         }
  31
  32         string label_str;
  33         for (const pair<string, string> &label : labels) {
  34                 if (!label_str.empty()) {
  35                         label_str += ",";
  36                 }
  37                 label_str += label.first + "=\"" + label.second + "\"";
  38         }
  39         return "{" + label_str + "}";
  40 }
  41
  42 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, atomic<int64_t> *location, Metrics::Type type)
  43 {
  44         Metric metric;
  45         metric.data_type = DATA_TYPE_INT64;
  46         metric.location_int64 = location;
  47
  48         lock_guard<mutex> lock(mu);
  49         metrics.emplace(MetricKey(name, labels), metric);
  50         assert(types.count(name) == 0 || types[name] == type);
  51         types[name] = type;
  52 }
  53
  54 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, atomic<double> *location, Metrics::Type type)
  55 {
  56         Metric metric;
  57         metric.data_type = DATA_TYPE_DOUBLE;
  58         metric.location_double = location;
  59
  60         lock_guard<mutex> lock(mu);
  61         metrics.emplace(MetricKey(name, labels), metric);
  62         assert(types.count(name) == 0 || types[name] == type);
  63         types[name] = type;
  64 }
  65
  66 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, Histogram *location, Laziness laziness)
  67 {
  68         Metric metric;
  69         metric.data_type = DATA_TYPE_HISTOGRAM;
  70         metric.laziness = laziness;
  71         metric.location_histogram = location;
  72
  73         lock_guard<mutex> lock(mu);
  74         metrics.emplace(MetricKey(name, labels), metric);
  75         assert(types.count(name) == 0 || types[name] == TYPE_HISTOGRAM);
  76         types[name] = TYPE_HISTOGRAM;
  77 }
  78
  79 void Metrics::remove(const string &name, const vector<pair<string, string>> &labels)
  80 {
  81         lock_guard<mutex> lock(mu);
  82
  83         auto it = metrics.find(MetricKey(name, labels));
  84         assert(it != metrics.end());
  85
  86         // If this is the last metric with this name, remove the type as well.
  87         if (!((it != metrics.begin() && prev(it)->first.name == name) ||
  88               (it != metrics.end() && next(it)->first.name == name))) {
  89                 types.erase(name);
  90         }
  91
  92         metrics.erase(it);
  93 }
  94
  95 string Metrics::serialize() const
  96 {
  97         stringstream ss;
  98         ss.imbue(locale("C"));
  99         ss.precision(20);
 100
 101         lock_guard<mutex> lock(mu);
 102         auto type_it = types.cbegin();
 103         for (const auto &key_and_metric : metrics) {
 104                 string name = "nageru_" + key_and_metric.first.name + key_and_metric.first.serialized_labels;
 105                 const Metric &metric = key_and_metric.second;
 106
 107                 if (type_it != types.cend() &&
 108                     key_and_metric.first.name == type_it->first) {
 109                         // It's the first time we print out any metric with this name,
 110                         // so add the type header.
 111                         if (type_it->second == TYPE_GAUGE) {
 112                                 ss << "# TYPE nageru_" << type_it->first << " gauge\n";
 113                         } else if (type_it->second == TYPE_HISTOGRAM) {
 114                                 ss << "# TYPE nageru_" << type_it->first << " histogram\n";
 115                         }
 116                         ++type_it;
 117                 }
 118
 119                 if (metric.data_type == DATA_TYPE_INT64) {
 120                         ss << name << " " << metric.location_int64->load() << "\n";
 121                 } else if (metric.data_type == DATA_TYPE_DOUBLE) {
 122                         double val = metric.location_double->load();
 123                         if (isnan(val)) {
 124                                 // Prometheus can't handle “-nan”.
 125                                 ss << name << " NaN\n";
 126                         } else {
 127                                 ss << name << " " << val << "\n";
 128                         }
 129                 } else {
 130                         ss << metric.location_histogram->serialize(metric.laziness, key_and_metric.first.name, key_and_metric.first.labels);
 131                 }
 132         }
 133
 134         return ss.str();
 135 }
 136
 137 void Histogram::init(const vector<double> &bucket_vals)
 138 {
 139         this->num_buckets = bucket_vals.size();
 140         buckets.reset(new Bucket[num_buckets]);
 141         for (size_t i = 0; i < num_buckets; ++i) {
 142                 buckets[i].val = bucket_vals[i];
 143         }
 144 }
 145
 146 void Histogram::init_uniform(size_t num_buckets)
 147 {
 148         this->num_buckets = num_buckets;
 149         buckets.reset(new Bucket[num_buckets]);
 150         for (size_t i = 0; i < num_buckets; ++i) {
 151                 buckets[i].val = i;
 152         }
 153 }
 154
 155 void Histogram::init_geometric(double min, double max, size_t num_buckets)
 156 {
 157         this->num_buckets = num_buckets;
 158         buckets.reset(new Bucket[num_buckets]);
 159         for (size_t i = 0; i < num_buckets; ++i) {
 160                 buckets[i].val = min * pow(max / min, double(i) / (num_buckets - 1));
 161         }
 162 }
 163
 164 void Histogram::count_event(double val)
 165 {
 166         Bucket ref_bucket;
 167         ref_bucket.val = val;
 168         auto it = lower_bound(buckets.get(), buckets.get() + num_buckets, ref_bucket,
 169                 [](const Bucket &a, const Bucket &b) { return a.val < b.val; });
 170         if (it == buckets.get() + num_buckets) {
 171                 ++count_after_last_bucket;
 172         } else {
 173                 ++it->count;
 174         }
 175         // Non-atomic add, but that's fine, since there are no concurrent writers.
 176         sum = sum + val;
 177 }
 178
 179 string Histogram::serialize(Metrics::Laziness laziness, const string &name, const vector<pair<string, string>> &labels) const
 180 {
 181         // Check if the histogram is empty and should not be serialized.
 182         if (laziness == Metrics::PRINT_WHEN_NONEMPTY && count_after_last_bucket.load() == 0) {
 183                 bool empty = true;
 184                 for (size_t bucket_idx = 0; bucket_idx < num_buckets; ++bucket_idx) {
 185                         if (buckets[bucket_idx].count.load() != 0) {
 186                                 empty = false;
 187                                 break;
 188                         }
 189                 }
 190                 if (empty) {
 191                         return "";
 192                 }
 193         }
 194
 195         stringstream ss;
 196         ss.imbue(locale("C"));
 197         ss.precision(20);
 198
 199         int64_t count = 0;
 200         for (size_t bucket_idx = 0; bucket_idx < num_buckets; ++bucket_idx) {
 201                 stringstream le_ss;
 202                 le_ss.imbue(locale("C"));
 203                 le_ss.precision(20);
 204                 le_ss << buckets[bucket_idx].val;
 205                 vector<pair<string, string>> bucket_labels = labels;
 206                 bucket_labels.emplace_back("le", le_ss.str());
 207
 208                 count += buckets[bucket_idx].count.load();
 209                 ss << Metrics::serialize_name(name + "_bucket", bucket_labels) << " " << count << "\n";
 210         }
 211
 212         count += count_after_last_bucket.load();
 213
 214         ss << Metrics::serialize_name(name + "_sum", labels) << " " << sum.load() << "\n";
 215         ss << Metrics::serialize_name(name + "_count", labels) << " " << count << "\n";
 216
 217         return ss.str();
 218 }