Add the first beginnings of Prometheus metrics.

[nageru] / metrics.h

diff --git a/metrics.h b/metrics.h
new file mode 100644 (file)
index 0000000..6c72ad5
--- /dev/null
+++ b/metrics.h
@@ -0,0 +1,28 @@
+#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 <mutex>
+#include <string>
+#include <unordered_map>
+
+class Metrics {
+public:
+       void register_int_metric(const std::string &name, std::atomic<int64_t> *location);
+       void register_double_metric(const std::string &name, std::atomic<double> *location);
+       std::string serialize() const;
+
+private:
+       mutable std::mutex mu;
+       std::unordered_map<std::string, std::atomic<int64_t> *> int_metrics;
+       std::unordered_map<std::string, std::atomic<double> *> double_metrics;
+};
+
+extern Metrics global_metrics;
+
+#endif  // !defined(_METRICS_H)