X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=metrics.h;h=e2e1e74f5ac9bb818f5bbdb8e6798ec27cadf869;hb=b9feb66845bf24465b7671ac9ff7a52b88f6032b;hp=a570723dae713f218c9b46c8f0d865ff71e526ad;hpb=c574aef4437253dcf0e6c1fed4c9cab1033b33f9;p=nageru

diff --git a/metrics.h b/metrics.h
index a570723..e2e1e74 100644
--- a/metrics.h
+++ b/metrics.h
@@ -7,13 +7,23 @@
 // 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:
@@ -21,6 +31,11 @@ public:
 		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)
@@ -38,42 +53,78 @@ public:
 		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);
+	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;
-		std::string name;
-		std::vector<std::pair<std::string, std::string>> labels;
+		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;
-	std::vector<Metric> metrics;
-	std::vector<Histogram> histograms;
+	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(const std::string &name, const std::vector<std::pair<std::string, std::string>> &labels) const;
+	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].
@@ -89,6 +140,25 @@ private:
 	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)