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

   1 #include "shared/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 string Metrics::prefix = "nageru";
  16
  17 double get_timestamp_for_metrics()
  18 {
  19         return duration<double>(system_clock::now().time_since_epoch()).count();
  20 }
  21
  22 string Metrics::serialize_name(const string &name, const vector<pair<string, string>> &labels)
  23 {
  24         return prefix + "_" + name + serialize_labels(labels);
  25 }
  26
  27 string Metrics::serialize_labels(const vector<pair<string, string>> &labels)
  28 {
  29         if (labels.empty()) {
  30                 return "";
  31         }
  32
  33         string label_str;
  34         for (const pair<string, string> &label : labels) {
  35                 if (!label_str.empty()) {
  36                         label_str += ",";
  37                 }
  38                 label_str += label.first + "=\"" + label.second + "\"";
  39         }
  40         return "{" + label_str + "}";
  41 }
  42
  43 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, atomic<int64_t> *location, Metrics::Type type)
  44 {
  45         Metric metric;
  46         metric.data_type = DATA_TYPE_INT64;
  47         metric.location_int64 = location;
  48
  49         lock_guard<mutex> lock(mu);
  50         metrics.emplace(MetricKey(name, labels), metric);
  51         assert(types.count(name) == 0 || types[name] == type);
  52         types[name] = type;
  53 }
  54
  55 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, atomic<double> *location, Metrics::Type type)
  56 {
  57         Metric metric;
  58         metric.data_type = DATA_TYPE_DOUBLE;
  59         metric.location_double = location;
  60
  61         lock_guard<mutex> lock(mu);
  62         metrics.emplace(MetricKey(name, labels), metric);
  63         assert(types.count(name) == 0 || types[name] == type);
  64         types[name] = type;
  65 }
  66
  67 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, Histogram *location, Laziness laziness)
  68 {
  69         Metric metric;
  70         metric.data_type = DATA_TYPE_HISTOGRAM;
  71         metric.laziness = laziness;
  72         metric.location_histogram = location;
  73
  74         lock_guard<mutex> lock(mu);
  75         metrics.emplace(MetricKey(name, labels), metric);
  76         assert(types.count(name) == 0 || types[name] == TYPE_HISTOGRAM);
  77         types[name] = TYPE_HISTOGRAM;
  78 }
  79
  80 void Metrics::add(const string &name, const vector<pair<string, string>> &labels, Summary *location, Laziness laziness)
  81 {
  82         Metric metric;
  83         metric.data_type = DATA_TYPE_SUMMARY;
  84         metric.laziness = laziness;
  85         metric.location_summary = location;
  86
  87         lock_guard<mutex> lock(mu);
  88         metrics.emplace(MetricKey(name, labels), metric);
  89         assert(types.count(name) == 0 || types[name] == TYPE_SUMMARY);
  90         types[name] = TYPE_SUMMARY;
  91 }
  92
  93 void Metrics::remove(const string &name, const vector<pair<string, string>> &labels)
  94 {
  95         lock_guard<mutex> lock(mu);
  96
  97         auto it = metrics.find(MetricKey(name, labels));
  98         assert(it != metrics.end());
  99
 100         // If this is the last metric with this name, remove the type as well.
 101         if (!((it != metrics.begin() && prev(it)->first.name == name) ||
 102               (it != metrics.end() && next(it)->first.name == name))) {
 103                 types.erase(name);
 104         }
 105
 106         metrics.erase(it);
 107 }
 108
 109 string Metrics::serialize() const
 110 {
 111         stringstream ss;
 112         ss.imbue(locale("C"));
 113         ss.precision(20);
 114
 115         lock_guard<mutex> lock(mu);
 116         auto type_it = types.cbegin();
 117         for (const auto &key_and_metric : metrics) {
 118                 string name = prefix + "_" + key_and_metric.first.name + key_and_metric.first.serialized_labels;
 119                 const Metric &metric = key_and_metric.second;
 120
 121                 if (type_it != types.cend() &&
 122                     key_and_metric.first.name == type_it->first) {
 123                         // It's the first time we print out any metric with this name,
 124                         // so add the type header.
 125                         if (type_it->second == TYPE_GAUGE) {
 126                                 ss << "# TYPE " + prefix + "_" << type_it->first << " gauge\n";
 127                         } else if (type_it->second == TYPE_HISTOGRAM) {
 128                                 ss << "# TYPE " + prefix + "_" << type_it->first << " histogram\n";
 129                         } else if (type_it->second == TYPE_SUMMARY) {
 130                                 ss << "# TYPE " + prefix + "_" << type_it->first << " summary\n";
 131                         }
 132                         ++type_it;
 133                 }
 134
 135                 if (metric.data_type == DATA_TYPE_INT64) {
 136                         ss << name << " " << metric.location_int64->load() << "\n";
 137                 } else if (metric.data_type == DATA_TYPE_DOUBLE) {
 138                         double val = metric.location_double->load();
 139                         if (isnan(val)) {
 140                                 // Prometheus can't handle “-nan”.
 141                                 ss << name << " NaN\n";
 142                         } else {
 143                                 ss << name << " " << val << "\n";
 144                         }
 145                 } else if (metric.data_type == DATA_TYPE_HISTOGRAM) {
 146                         ss << metric.location_histogram->serialize(metric.laziness, key_and_metric.first.name, key_and_metric.first.labels);
 147                 } else {
 148                         ss << metric.location_summary->serialize(metric.laziness, key_and_metric.first.name, key_and_metric.first.labels);
 149                 }
 150         }
 151
 152         return ss.str();
 153 }
 154
 155 void Histogram::init(const vector<double> &bucket_vals)
 156 {
 157         this->num_buckets = bucket_vals.size();
 158         buckets.reset(new Bucket[num_buckets]);
 159         for (size_t i = 0; i < num_buckets; ++i) {
 160                 buckets[i].val = bucket_vals[i];
 161         }
 162 }
 163
 164 void Histogram::init_uniform(size_t num_buckets)
 165 {
 166         this->num_buckets = num_buckets;
 167         buckets.reset(new Bucket[num_buckets]);
 168         for (size_t i = 0; i < num_buckets; ++i) {
 169                 buckets[i].val = i;
 170         }
 171 }
 172
 173 void Histogram::init_geometric(double min, double max, size_t num_buckets)
 174 {
 175         this->num_buckets = num_buckets;
 176         buckets.reset(new Bucket[num_buckets]);
 177         for (size_t i = 0; i < num_buckets; ++i) {
 178                 buckets[i].val = min * pow(max / min, double(i) / (num_buckets - 1));
 179         }
 180 }
 181
 182 void Histogram::count_event(double val)
 183 {
 184         Bucket ref_bucket;
 185         ref_bucket.val = val;
 186         auto it = lower_bound(buckets.get(), buckets.get() + num_buckets, ref_bucket,
 187                 [](const Bucket &a, const Bucket &b) { return a.val < b.val; });
 188         if (it == buckets.get() + num_buckets) {
 189                 ++count_after_last_bucket;
 190         } else {
 191                 ++it->count;
 192         }
 193         // Non-atomic add, but that's fine, since there are no concurrent writers.
 194         sum = sum + val;
 195 }
 196
 197 string Histogram::serialize(Metrics::Laziness laziness, const string &name, const vector<pair<string, string>> &labels) const
 198 {
 199         // Check if the histogram is empty and should not be serialized.
 200         if (laziness == Metrics::PRINT_WHEN_NONEMPTY && count_after_last_bucket.load() == 0) {
 201                 bool empty = true;
 202                 for (size_t bucket_idx = 0; bucket_idx < num_buckets; ++bucket_idx) {
 203                         if (buckets[bucket_idx].count.load() != 0) {
 204                                 empty = false;
 205                                 break;
 206                         }
 207                 }
 208                 if (empty) {
 209                         return "";
 210                 }
 211         }
 212
 213         stringstream ss;
 214         ss.imbue(locale("C"));
 215         ss.precision(20);
 216
 217         int64_t count = 0;
 218         for (size_t bucket_idx = 0; bucket_idx < num_buckets; ++bucket_idx) {
 219                 stringstream le_ss;
 220                 le_ss.imbue(locale("C"));
 221                 le_ss.precision(20);
 222                 le_ss << buckets[bucket_idx].val;
 223                 vector<pair<string, string>> bucket_labels = labels;
 224                 bucket_labels.emplace_back("le", le_ss.str());
 225
 226                 count += buckets[bucket_idx].count.load();
 227                 ss << Metrics::serialize_name(name + "_bucket", bucket_labels) << " " << count << "\n";
 228         }
 229
 230         count += count_after_last_bucket.load();
 231
 232         ss << Metrics::serialize_name(name + "_sum", labels) << " " << sum.load() << "\n";
 233         ss << Metrics::serialize_name(name + "_count", labels) << " " << count << "\n";
 234
 235         return ss.str();
 236 }
 237
 238 void Summary::init(const vector<double> &quantiles, double window_seconds)
 239 {
 240         this->quantiles = quantiles;
 241         window = duration<double>(window_seconds);
 242 }
 243
 244 void Summary::count_event(double val)
 245 {
 246         steady_clock::time_point now = steady_clock::now();
 247         steady_clock::time_point cutoff = now - duration_cast<steady_clock::duration>(window);
 248
 249         lock_guard<mutex> lock(mu);
 250         values.emplace_back(now, val);
 251         while (!values.empty() && values.front().first < cutoff) {
 252                 values.pop_front();
 253         }
 254
 255         // Non-atomic add, but that's fine, since there are no concurrent writers.
 256         sum = sum + val;
 257         ++count;
 258 }
 259
 260 string Summary::serialize(Metrics::Laziness laziness, const string &name, const vector<pair<string, string>> &labels)
 261 {
 262         steady_clock::time_point now = steady_clock::now();
 263         steady_clock::time_point cutoff = now - duration_cast<steady_clock::duration>(window);
 264
 265         vector<double> values_copy;
 266         {
 267                 lock_guard<mutex> lock(mu);
 268                 while (!values.empty() && values.front().first < cutoff) {
 269                         values.pop_front();
 270                 }
 271                 values_copy.reserve(values.size());
 272                 for (const auto &time_and_value : values) {
 273                         values_copy.push_back(time_and_value.second);
 274                 }
 275         }
 276
 277         vector<pair<double, double>> answers;
 278         if (values_copy.size() == 0) {
 279                 if (laziness == Metrics::PRINT_WHEN_NONEMPTY) {
 280                         return "";
 281                 }
 282                 for (double quantile : quantiles) {
 283                         answers.emplace_back(quantile, 0.0 / 0.0);
 284                 }
 285         } else if (values_copy.size() == 1) {
 286                 for (double quantile : quantiles) {
 287                         answers.emplace_back(quantile, values_copy[0]);
 288                 }
 289         } else {
 290                 // We could probably do repeated nth_element, but the constant factor
 291                 // gets a bit high, so just sorting probably is about as fast.
 292                 sort(values_copy.begin(), values_copy.end());
 293                 for (double quantile : quantiles) {
 294                         double idx = quantile * (values_copy.size() - 1);
 295                         size_t idx_floor = size_t(floor(idx));
 296                         const double v0 = values_copy[idx_floor];
 297
 298                         if (idx_floor == values_copy.size() - 1) {
 299                                 answers.emplace_back(quantile, values_copy[idx_floor]);
 300                         } else {
 301                                 // Linear interpolation.
 302                                 double t = idx - idx_floor;
 303                                 const double v1 = values_copy[idx_floor + 1];
 304                                 answers.emplace_back(quantile, v0 + t * (v1 - v0));
 305                         }
 306                 }
 307         }
 308
 309         stringstream ss;
 310         ss.imbue(locale("C"));
 311         ss.precision(20);
 312
 313         for (const auto &quantile_and_value : answers) {
 314                 stringstream quantile_ss;
 315                 quantile_ss.imbue(locale("C"));
 316                 quantile_ss.precision(3);
 317                 quantile_ss << quantile_and_value.first;
 318                 vector<pair<string, string>> quantile_labels = labels;
 319                 quantile_labels.emplace_back("quantile", quantile_ss.str());
 320
 321                 double val = quantile_and_value.second;;
 322                 if (isnan(val)) {
 323                         // Prometheus can't handle “-nan”.
 324                         ss << Metrics::serialize_name(name, quantile_labels) << " NaN\n";
 325                 } else {
 326                         ss << Metrics::serialize_name(name, quantile_labels) << " " << val << "\n";
 327                 }
 328         }
 329
 330         ss << Metrics::serialize_name(name + "_sum", labels) << " " << sum.load() << "\n";
 331         ss << Metrics::serialize_name(name + "_count", labels) << " " << count.load() << "\n";
 332         return ss.str();
 333 }