Metrics API : Provider , MeterProvider, Meter, SynchronousInstrument

api/include/opentelemetry/metrics/async_instruments.h

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+#ifndef ENABLE_METRICS_PREVIEW
+
+#  include "observer_result.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace metrics
+{
+class AsynchronousInstrument
+{};
+
+template <class T>
+class ObservableCounter : public AsynchronousInstrument
+{};
+
+template <class T>
+class ObservableGauge : public AsynchronousInstrument
+{};
+
+template <class T>
+class ObservableUpDownCounter : public AsynchronousInstrument
+{};
+
+}  // namespace metrics
+OPENTELEMETRY_END_NAMESPACE
+#endif

api/include/opentelemetry/metrics/meter.h

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+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+#ifndef ENABLE_METRICS_PREVIEW
+
+#  include "opentelemetry/metrics/async_instruments.h"
+#  include "opentelemetry/metrics/sync_instruments.h"
+#  include "opentelemetry/nostd/shared_ptr.h"
+#  include "opentelemetry/nostd/span.h"
+#  include "opentelemetry/nostd/string_view.h"
+#  include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace metrics
+{
+/**
+ * Handles instrument creation and provides a facility for batch recording.
+ *
+ * This class provides methods to create new metric instruments, record a
+ * batch of values to a specified set of instruments, and collect
+ * measurements from all instruments.
+ *
+ */
+class Meter
+{
+public:
+  virtual ~Meter() = default;
+
+  /**
+   * Creates a Counter with the passed characteristics and returns a shared_ptr to that Counter.
+   *
+   * @param name the name of the new Counter.
+   * @param description a brief description of what the Counter is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   * @return a shared pointer to the created Counter.
+   */
+
+  virtual nostd::shared_ptr<Counter<long>> CreateLongCounter(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  virtual nostd::shared_ptr<Counter<double>> CreateDoubleCounter(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  /**
+   * Creates a Asynchronouse (Observable) counter with the passed characteristics and returns a
+   * shared_ptr to that Observable Counter
+   *
+   * @param name the name of the new Observable Counter.
+   * @param description a brief description of what the Observable Counter is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   * @param callback the function to be observed by the instrument.
+   * @return a shared pointer to the created Observable Counter.
+   */
+  virtual nostd::shared_ptr<ObservableCounter<long>> CreateLongObservableCounter(
+      nostd::string_view name,
+      void (*callback)(ObserverResult<long> &),
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  virtual nostd::shared_ptr<ObservableCounter<double>> CreateDoubleObservableCounter(
+      nostd::string_view name,
+      void (*callback)(ObserverResult<double> &),
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  /**
+   * Creates a Histogram with the passed characteristics and returns a shared_ptr to that Histogram.
+   *
+   * @param name the name of the new Histogram.
+   * @param description a brief description of what the Histogram is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   * @return a shared pointer to the created Histogram.
+   */
+  virtual nostd::shared_ptr<Histogram<long>> CreateLongHistogram(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  virtual nostd::shared_ptr<Histogram<double>> CreateDoubleHistogram(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  /**
+   * Creates a Asynchronouse (Observable) Gauge with the passed characteristics and returns a
+   * shared_ptr to that Observable Counter
+   *
+   * @param name the name of the new Observable Gauge.
+   * @param description a brief description of what the Observable Gauge is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   * @param callback the function to be observed by the instrument.
+   * @return a shared pointer to the created Observable Gauge.
+   */
+  virtual nostd::shared_ptr<ObservableGauge<long>> CreateLongObservableGauge(
+      nostd::string_view name,
+      void (*callback)(ObserverResult<long> &),
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  virtual nostd::shared_ptr<ObservableGauge<double>> CreateDoubleObservableGauge(
+      nostd::string_view name,
+      void (*callback)(ObserverResult<double> &),
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  /**
+   * Creates an UpDownCounter with the passed characteristics and returns a shared_ptr to that
+   * UpDownCounter.
+   *
+   * @param name the name of the new UpDownCounter.
+   * @param description a brief description of what the UpDownCounter is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   * @return a shared pointer to the created UpDownCounter.
+   */
+  virtual nostd::shared_ptr<UpDownCounter<long>> CreateLongUpDownCounter(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  virtual nostd::shared_ptr<UpDownCounter<double>> CreateDoubleUpDownCounter(
+      nostd::string_view name,
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  /**
+   * Creates a Asynchronouse (Observable) UpDownCounter with the passed characteristics and returns
+   * a shared_ptr to that Observable UpDownCounter
+   *
+   * @param name the name of the new Observable UpDownCounter.
+   * @param description a brief description of what the Observable UpDownCounter is used for.
+   * @param unit the unit of metric values following https://unitsofmeasure.org/ucum.html.
+   * @param callback the function to be observed by the instrument.
+   * @return a shared pointer to the created Observable UpDownCounter.
+   */
+  virtual nostd::shared_ptr<ObservableUpDownCounter<long>> CreateLongObservableUpDownCounter(
+      nostd::string_view name,
+      void (*callback)(ObserverResult<long> &),
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+
+  virtual nostd::shared_ptr<ObservableUpDownCounter<double>> CreateDoubleObservableUpDownCounter(
+      nostd::string_view name,
+      void (*callback)(ObserverResult<double> &),
+      nostd::string_view description = "",
+      nostd::string_view unit        = "1") noexcept = 0;
+};
+}  // namespace metrics
+OPENTELEMETRY_END_NAMESPACE
+#endif

api/include/opentelemetry/metrics/meter_provider.h

@@ -0,0 +1,33 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+#ifndef ENABLE_METRICS_PREVIEW
+
+#  include "opentelemetry/metrics/meter.h"
+#  include "opentelemetry/nostd/shared_ptr.h"
+#  include "opentelemetry/nostd/string_view.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace metrics
+{
+/**
+ * Creates new Meter instances.
+ */
+class MeterProvider
+{
+public:
+  virtual ~MeterProvider() = default;
+  /**
+   * Gets or creates a named Meter instance.
+   *
+   * Optionally a version can be passed to create a named and versioned Meter
+   * instance.
+   */
+  virtual nostd::shared_ptr<Meter> GetMeter(nostd::string_view library_name,
+                                            nostd::string_view library_version = "",
+                                            nostd::string_view schema_url      = "") noexcept = 0;
+};
+}  // namespace metrics
+OPENTELEMETRY_END_NAMESPACE
+#endif