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)
  67 {
  68         Metric metric;
  69         metric.data_type = DATA_TYPE_HISTOGRAM;
  70         metric.location_histogram = location;
  71
  72         lock_guard<mutex> lock(mu);
  73         metrics.emplace(MetricKey(name, labels), metric);
  74         assert(types.count(name) == 0 || types[name] == TYPE_HISTOGRAM);
  75         types[name] = TYPE_HISTOGRAM;
  76 }
  77
  78 string Metrics::serialize() const
  79 {
  80         stringstream ss;
  81         ss.imbue(locale("C"));
  82         ss.precision(20);
  83
  84         lock_guard<mutex> lock(mu);
  85         auto type_it = types.cbegin();
  86         for (const auto &key_and_metric : metrics) {
  87                 string name = "nageru_" + key_and_metric.first.name + key_and_metric.first.serialized_labels;
  88                 const Metric &metric = key_and_metric.second;
  89
  90                 if (type_it != types.cend() &&
  91                     key_and_metric.first.name == type_it->first) {
  92                         // It's the first time we print out any metric with this name,
  93                         // so add the type header.
  94                         if (type_it->second == TYPE_GAUGE) {
  95                                 ss << "# TYPE nageru_" << type_it->first << " gauge\n";
  96                         } else if (type_it->second == TYPE_HISTOGRAM) {
  97                                 ss << "# TYPE nageru_" << type_it->first << " histogram\n";
  98                         }
  99                         ++type_it;
 100                 }
 101
 102                 if (metric.data_type == DATA_TYPE_INT64) {
 103                         ss << name << " " << metric.location_int64->load() << "\n";
 104                 } else if (metric.data_type == DATA_TYPE_DOUBLE) {
 105                         ss << name << " " << metric.location_double->load() << "\n";
 106                 } else {
 107                         ss << metric.location_histogram->serialize(key_and_metric.first.name, key_and_metric.first.labels);
 108                 }
 109         }
 110
 111         return ss.str();
 112 }
 113
 114 void Histogram::init(const vector<double> &bucket_vals)
 115 {
 116         this->num_buckets = bucket_vals.size();
 117         buckets.reset(new Bucket[num_buckets]);
 118         for (size_t i = 0; i < num_buckets; ++i) {
 119                 buckets[i].val = bucket_vals[i];
 120         }
 121 }
 122
 123 void Histogram::init_uniform(size_t num_buckets)
 124 {
 125         this->num_buckets = num_buckets;
 126         buckets.reset(new Bucket[num_buckets]);
 127         for (size_t i = 0; i < num_buckets; ++i) {
 128                 buckets[i].val = i;
 129         }
 130 }
 131
 132 void Histogram::init_geometric(double min, double max, size_t num_buckets)
 133 {
 134         this->num_buckets = num_buckets;
 135         buckets.reset(new Bucket[num_buckets]);
 136         for (size_t i = 0; i < num_buckets; ++i) {
 137                 buckets[i].val = min * pow(max / min, double(i) / (num_buckets - 1));
 138         }
 139 }
 140
 141 void Histogram::count_event(double val)
 142 {
 143         Bucket ref_bucket;
 144         ref_bucket.val = val;
 145         auto it = lower_bound(buckets.get(), buckets.get() + num_buckets, ref_bucket,
 146                 [](const Bucket &a, const Bucket &b) { return a.val < b.val; });
 147         if (it == buckets.get() + num_buckets) {
 148                 ++count_after_last_bucket;
 149         } else {
 150                 ++it->count;
 151         }
 152         // Non-atomic add, but that's fine, since there are no concurrent writers.
 153         sum = sum + val;
 154 }
 155
 156 string Histogram::serialize(const string &name, const vector<pair<string, string>> &labels) const
 157 {
 158         stringstream ss;
 159         ss.imbue(locale("C"));
 160         ss.precision(20);
 161
 162         int64_t count = 0;
 163         for (size_t bucket_idx = 0; bucket_idx < num_buckets; ++bucket_idx) {
 164                 stringstream le_ss;
 165                 le_ss.imbue(locale("C"));
 166                 le_ss.precision(20);
 167                 le_ss << buckets[bucket_idx].val;
 168                 vector<pair<string, string>> bucket_labels = labels;
 169                 bucket_labels.emplace_back("le", le_ss.str());
 170
 171                 count += buckets[bucket_idx].count.load();
 172                 ss << Metrics::serialize_name(name + "_bucket", bucket_labels) << " " << count << "\n";
 173         }
 174
 175         count += count_after_last_bucket.load();
 176
 177         ss << Metrics::serialize_name(name + "_sum", labels) << " " << sum.load() << "\n";
 178         ss << Metrics::serialize_name(name + "_count", labels) << " " << count << "\n";
 179
 180         return ss.str();
 181 }