update ceph source to reef 18.1.2

[ceph.git] / ceph / src / jaegertracing / opentelemetry-cpp / third_party / prometheus-cpp / core / include / prometheus / gauge.h

diff --git a/ceph/src/jaegertracing/opentelemetry-cpp/third_party/prometheus-cpp/core/include/prometheus/gauge.h b/ceph/src/jaegertracing/opentelemetry-cpp/third_party/prometheus-cpp/core/include/prometheus/gauge.h
new file mode 100644 (file)
index 0000000..01d0e07
--- /dev/null
+++ b/ceph/src/jaegertracing/opentelemetry-cpp/third_party/prometheus-cpp/core/include/prometheus/gauge.h
@@ -0,0 +1,94 @@
+#pragma once
+
+#include <atomic>
+
+#include "prometheus/client_metric.h"
+#include "prometheus/detail/builder.h"  // IWYU pragma: export
+#include "prometheus/detail/core_export.h"
+#include "prometheus/metric_type.h"
+
+namespace prometheus {
+
+/// \brief A gauge metric to represent a value that can arbitrarily go up and
+/// down.
+///
+/// The class represents the metric type gauge:
+/// https://prometheus.io/docs/concepts/metric_types/#gauge
+///
+/// Gauges are typically used for measured values like temperatures or current
+/// memory usage, but also "counts" that can go up and down, like the number of
+/// running processes.
+///
+/// The class is thread-safe. No concurrent call to any API of this type causes
+/// a data race.
+class PROMETHEUS_CPP_CORE_EXPORT Gauge {
+ public:
+  static const MetricType metric_type{MetricType::Gauge};
+
+  /// \brief Create a gauge that starts at 0.
+  Gauge() = default;
+
+  /// \brief Create a gauge that starts at the given amount.
+  Gauge(double);
+
+  /// \brief Increment the gauge by 1.
+  void Increment();
+
+  /// \brief Increment the gauge by the given amount.
+  void Increment(double);
+
+  /// \brief Decrement the gauge by 1.
+  void Decrement();
+
+  /// \brief Decrement the gauge by the given amount.
+  void Decrement(double);
+
+  /// \brief Set the gauge to the given value.
+  void Set(double);
+
+  /// \brief Set the gauge to the current unixtime in seconds.
+  void SetToCurrentTime();
+
+  /// \brief Get the current value of the gauge.
+  double Value() const;
+
+  /// \brief Get the current value of the gauge.
+  ///
+  /// Collect is called by the Registry when collecting metrics.
+  ClientMetric Collect() const;
+
+ private:
+  void Change(double);
+  std::atomic<double> value_{0.0};
+};
+
+/// \brief Return a builder to configure and register a Gauge metric.
+///
+/// @copydetails Family<>::Family()
+///
+/// Example usage:
+///
+/// \code
+/// auto registry = std::make_shared<Registry>();
+/// auto& gauge_family = prometheus::BuildGauge()
+///                          .Name("some_name")
+///                          .Help("Additional description.")
+///                          .Labels({{"key", "value"}})
+///                          .Register(*registry);
+///
+/// ...
+/// \endcode
+///
+/// \return An object of unspecified type T, i.e., an implementation detail
+/// except that it has the following members:
+///
+/// - Name(const std::string&) to set the metric name,
+/// - Help(const std::string&) to set an additional description.
+/// - Labels(const Labels&) to assign a set of
+///   key-value pairs (= labels) to the metric.
+///
+/// To finish the configuration of the Gauge metric register it with
+/// Register(Registry&).
+PROMETHEUS_CPP_CORE_EXPORT detail::Builder<Gauge> BuildGauge();
+
+}  // namespace prometheus