+++ /dev/null
-#ifndef _METRICS_H
-#define _METRICS_H 1
-
-// A simple global class to keep track of metrics export in Prometheus format.
-// It would be better to use a more full-featured Prometheus client library for this,
-// but it would introduce a dependency that is not commonly packaged in distributions,
-// which makes it quite unwieldy. Thus, we'll package our own for the time being.
-
-#include <atomic>
-#include <chrono>
-#include <deque>
-#include <map>
-#include <memory>
-#include <mutex>
-#include <string>
-#include <utility>
-#include <vector>
-
-class Histogram;
-class Summary;
-
-// Prometheus recommends the use of timestamps instead of “time since event”,
-// so you can use this to get the number of seconds since the epoch.
-// Note that this will be wrong if your clock changes, so for non-metric use,
-// you should use std::chrono::steady_clock instead.
-double get_timestamp_for_metrics();
-
-class Metrics {
-public:
- enum Type {
- TYPE_COUNTER,
- TYPE_GAUGE,
- TYPE_HISTOGRAM, // Internal use only.
- TYPE_SUMMARY, // Internal use only.
- };
- enum Laziness {
- PRINT_ALWAYS,
- PRINT_WHEN_NONEMPTY,
- };
-
- void add(const std::string &name, std::atomic<int64_t> *location, Type type = TYPE_COUNTER)
- {
- add(name, {}, location, type);
- }
-
- void add(const std::string &name, std::atomic<double> *location, Type type = TYPE_COUNTER)
- {
- add(name, {}, location, type);
- }
-
- void add(const std::string &name, Histogram *location)
- {
- add(name, {}, location);
- }
-
- void add(const std::string &name, Summary *location)
- {
- add(name, {}, location);
- }
-
- void add(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels, std::atomic<int64_t> *location, Type type = TYPE_COUNTER);
- void add(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels, std::atomic<double> *location, Type type = TYPE_COUNTER);
- void add(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels, Histogram *location, Laziness laziness = PRINT_ALWAYS);
- void add(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels, Summary *location, Laziness laziness = PRINT_ALWAYS);
-
- void remove(const std::string &name)
- {
- remove(name, {});
- }
-
- void remove(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels);
-
- std::string serialize() const;
-
-private:
- static std::string serialize_name(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels);
- static std::string serialize_labels(const std::vector<std::pair<std::string, std::string>> &labels);
-
- enum DataType {
- DATA_TYPE_INT64,
- DATA_TYPE_DOUBLE,
- DATA_TYPE_HISTOGRAM,
- DATA_TYPE_SUMMARY,
- };
- struct MetricKey {
- MetricKey(const std::string &name, const std::vector<std::pair<std::string, std::string>> labels)
- : name(name), labels(labels), serialized_labels(serialize_labels(labels))
- {
- }
-
- bool operator< (const MetricKey &other) const
- {
- if (name != other.name)
- return name < other.name;
- return serialized_labels < other.serialized_labels;
- }
-
- const std::string name;
- const std::vector<std::pair<std::string, std::string>> labels;
- const std::string serialized_labels;
- };
- struct Metric {
- DataType data_type;
- Laziness laziness; // Only for TYPE_HISTOGRAM.
- union {
- std::atomic<int64_t> *location_int64;
- std::atomic<double> *location_double;
- Histogram *location_histogram;
- Summary *location_summary;
- };
- };
-
- mutable std::mutex mu;
- std::map<std::string, Type> types; // Ordered the same as metrics.
- std::map<MetricKey, Metric> metrics;
-
- friend class Histogram;
- friend class Summary;
-};
-
-class Histogram {
-public:
- void init(const std::vector<double> &bucket_vals);
- void init_uniform(size_t num_buckets); // Sets up buckets 0..(N-1).
- void init_geometric(double min, double max, size_t num_buckets);
- void count_event(double val);
- std::string serialize(Metrics::Laziness laziness, const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels) const;
-
-private:
- // Bucket <i> counts number of events where val[i - 1] < x <= val[i].
- // The end histogram ends up being made into a cumulative one,
- // but that's not how we store it here.
- struct Bucket {
- double val;
- std::atomic<int64_t> count{0};
- };
- std::unique_ptr<Bucket[]> buckets;
- size_t num_buckets;
- std::atomic<double> sum{0.0};
- std::atomic<int64_t> count_after_last_bucket{0};
-};
-
-// This is a pretty dumb streaming quantile class, but it's exact, and we don't have
-// too many values (typically one per frame, and one-minute interval), so we don't
-// need anything fancy.
-class Summary {
-public:
- void init(const std::vector<double> &quantiles, double window_seconds);
- void count_event(double val);
- std::string serialize(Metrics::Laziness laziness, const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels);
-
-private:
- std::vector<double> quantiles;
- std::chrono::duration<double> window;
-
- mutable std::mutex mu;
- std::deque<std::pair<std::chrono::steady_clock::time_point, double>> values;
- std::atomic<double> sum{0.0};
- std::atomic<int64_t> count{0};
-};
-
-extern Metrics global_metrics;
-
-#endif // !defined(_METRICS_H)
projects / nageru / blobdiff