initial commit

api/include/opentelemetry/metrics/meter.h

@@ -21,6 +21,9 @@ class Histogram;
 template <typename T>
 class UpDownCounter;
 
+template <typename T>
+class Gauge;
+
 class ObservableInstrument;
 
 /**
@@ -91,6 +94,24 @@ class Meter
       nostd::string_view description = "",
       nostd::string_view unit        = "") noexcept = 0;
 
+  /**
+   * Creates a Gauge with the passed characteristics and returns a
+   * unique_ptr to that Gauge
+   *
+   * @param name the name of the new Gauge.
+   * @param description a brief description of what the Gauge is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   */
+  virtual nostd::unique_ptr<Gauge<uint64_t>> CreateInt64Gauge(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "") noexcept = 0;
+
+  virtual nostd::unique_ptr<Gauge<double>> CreateDoubleGauge(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "") noexcept = 0;
+
   /**
    * Creates a Asynchronouse (Observable) Gauge with the passed characteristics and returns a
    * shared_ptr to that Observable Gauge

api/include/opentelemetry/metrics/sync_instruments.h

@@ -194,5 +194,47 @@ class UpDownCounter : public SynchronousInstrument
   }
 };
 
+/** An Gauge instrument that records value. */
+
+template <class T>
+class Gauge : public SynchronousInstrument
+{
+public:
+  /**
+   * Records the current value.
+   *
+   * @param value The measurement value. MUST be non-negative.
+   */
+  virtual void Record(T value, const context::Context &context) noexcept = 0;
+
+  /**
+   * Records a value with a set of attributes.
+   *
+   * @param value The measurement value. MUST be non-negative.
+   * @param attributes A set of attributes to associate with the value.
+   */
+  virtual void Record(T value,
+                      const common::KeyValueIterable &attributes,
+                      const context::Context &context) noexcept = 0;
+
+  template <class U,
+            nostd::enable_if_t<common::detail::is_key_value_iterable<U>::value> * = nullptr>
+  void Record(T value, const U &attributes, const context::Context &context) noexcept
+  {
+    this->Record(value, common::KeyValueIterableView<U>{attributes}, context);
+  }
+
+  void Record(
+      T value,
+      std::initializer_list<std::pair<nostd::string_view, common::AttributeValue>> attributes,
+      const context::Context &context) noexcept
+  {
+    this->Record(value,
+                 nostd::span<const std::pair<nostd::string_view, common::AttributeValue>>{
+                     attributes.begin(), attributes.end()},
+                 context);
+  }
+};
+
 }  // namespace metrics
 OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/metrics/meter.h

@@ -74,6 +74,16 @@ class Meter final : public opentelemetry::metrics::Meter
       nostd::string_view description = "",
       nostd::string_view unit        = "") noexcept override;
 
+  nostd::unique_ptr<opentelemetry::metrics::Gauge<uint64_t>> CreateInt64Gauge(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "") noexcept override;
+
+  nostd::unique_ptr<opentelemetry::metrics::Gauge<double>> CreateDoubleGauge(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "") noexcept override;
+
   nostd::shared_ptr<opentelemetry::metrics::ObservableInstrument> CreateInt64ObservableGauge(
       nostd::string_view name,
       nostd::string_view description = "",

sdk/include/opentelemetry/sdk/metrics/sync_instruments.h

@@ -196,6 +196,37 @@ class DoubleHistogram : public Synchronous, public opentelemetry::metrics::Histo
   void Record(double value, const opentelemetry::context::Context &context) noexcept override;
 };
 
+class LongGauge : public Synchronous, public opentelemetry::metrics::Gauge<int64_t>
+{
+{
+public:
+  /**
+   * Records the current value.
+   *
+   * @param value The measurement value. MUST be non-negative.
+   */
+  virtual void Record(int64_t value, const context::Context &context) noexcept{
+
+  }
+
+};
+
+class DoubleGauge : public Synchronous, public opentelemetry::metrics::Gauge<double>
+{
+{
+public:
+  /**
+   * Records the current value.
+   *
+   * @param value The measurement value. MUST be non-negative.
+   */
+  virtual void Record(int64_t value, const context::Context &context) noexcept{
+
+  }
+
+};
+
+
 }  // namespace metrics
 }  // namespace sdk
 OPENTELEMETRY_END_NAMESPACE