Get rid of obsolete core namespace in API

CHANGELOG.md

@@ -15,6 +15,8 @@ Increment the:
 
 ## [Unreleased]
 
+* [API] Move class from opentelemetry::core namespace to opentelemetry::common namespace ([#686](https://github.com/open-telemetry/opentelemetry-cpp/pull/686))
+
 ## [0.4.0] 2021-04-12
 
 * [EXPORTER] ETW Exporter enhancements ([#519](https://github.com/open-telemetry/opentelemetry-cpp/pull/519))

api/include/opentelemetry/core/timestamp.h → api/include/opentelemetry/common/timestamp.h

@@ -7,26 +7,46 @@
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
-namespace core
+namespace common
 {
 /**
- * Represents a timepoint relative to the system clock epoch
+ * @brief A timepoint relative to the system clock epoch.
+ *
+ * This is used for marking the beginning and end of an operation.
  */
 class SystemTimestamp
 {
 public:
+  /**
+   * @brief Initializes a system timestamp pointing to the start of the epoch.
+   */
   SystemTimestamp() noexcept : nanos_since_epoch_{0} {}
 
+  /**
+   * @brief Initializes a system timestamp from a duration.
+   *
+   * @param time_since_epoch Time elapsed since the beginning of the epoch.
+   */
   template <class Rep, class Period>
   explicit SystemTimestamp(const std::chrono::duration<Rep, Period> &time_since_epoch) noexcept
       : nanos_since_epoch_{static_cast<int64_t>(
             std::chrono::duration_cast<std::chrono::nanoseconds>(time_since_epoch).count())}
   {}
 
+  /**
+   * @brief Initializes a system timestamp based on a point in time.
+   *
+   * @param time_point A point in time.
+   */
   /*implicit*/ SystemTimestamp(const std::chrono::system_clock::time_point &time_point) noexcept
       : SystemTimestamp{time_point.time_since_epoch()}
   {}
 
+  /**
+   * @brief Returns a time point for the time stamp.
+   *
+   * @return A time point corresponding to the time stamp.
+   */
   operator std::chrono::system_clock::time_point() const noexcept
   {
     return std::chrono::system_clock::time_point{
@@ -35,18 +55,30 @@ class SystemTimestamp
   }
 
   /**
-   * @return the amount of time that has passed since the system clock epoch
+   * @brief Returns the nanoseconds since the beginning of the epoch.
+   *
+   * @return Elapsed nanoseconds since the beginning of the epoch for this timestamp.
    */
   std::chrono::nanoseconds time_since_epoch() const noexcept
   {
     return std::chrono::nanoseconds{nanos_since_epoch_};
   }
 
+  /**
+   * @brief Compare two steady time stamps.
+   *
+   * @return true if the two time stamps are equal.
+   */
   bool operator==(const SystemTimestamp &other) const noexcept
   {
     return nanos_since_epoch_ == other.nanos_since_epoch_;
   }
 
+  /**
+   * @brief Compare two steady time stamps for inequality.
+   *
+   * @return true if the two time stamps are not equal.
+   */
   bool operator!=(const SystemTimestamp &other) const noexcept
   {
     return nanos_since_epoch_ != other.nanos_since_epoch_;
@@ -57,23 +89,43 @@ class SystemTimestamp
 };
 
 /**
- * Represents a timepoint relative to the monotonic clock epoch
+ * @brief A timepoint relative to the monotonic clock epoch
+ *
+ * This is used for calculating the duration of an operation.
  */
 class SteadyTimestamp
 {
 public:
+  /**
+   * @brief Initializes a monotonic timestamp pointing to the start of the epoch.
+   */
   SteadyTimestamp() noexcept : nanos_since_epoch_{0} {}
 
+  /**
+   * @brief Initializes a monotonic timestamp from a duration.
+   *
+   * @param time_since_epoch Time elapsed since the beginning of the epoch.
+   */
   template <class Rep, class Period>
   explicit SteadyTimestamp(const std::chrono::duration<Rep, Period> &time_since_epoch) noexcept
       : nanos_since_epoch_{static_cast<int64_t>(
             std::chrono::duration_cast<std::chrono::nanoseconds>(time_since_epoch).count())}
   {}
 
+  /**
+   * @brief Initializes a monotonic timestamp based on a point in time.
+   *
+   * @param time_point A point in time.
+   */
   /*implicit*/ SteadyTimestamp(const std::chrono::steady_clock::time_point &time_point) noexcept
       : SteadyTimestamp{time_point.time_since_epoch()}
   {}
 
+  /**
+   * @brief Returns a time point for the time stamp.
+   *
+   * @return A time point corresponding to the time stamp.
+   */
   operator std::chrono::steady_clock::time_point() const noexcept
   {
     return std::chrono::steady_clock::time_point{
@@ -82,18 +134,30 @@ class SteadyTimestamp
   }
 
   /**
-   * @return the amount of time that has passed since the monotonic clock epoch
+   * @brief Returns the nanoseconds since the beginning of the epoch.
+   *
+   * @return Elapsed nanoseconds since the beginning of the epoch for this timestamp.
    */
   std::chrono::nanoseconds time_since_epoch() const noexcept
   {
     return std::chrono::nanoseconds{nanos_since_epoch_};
   }
 
+  /**
+   * @brief Compare two steady time stamps.
+   *
+   * @return true if the two time stamps are equal.
+   */
   bool operator==(const SteadyTimestamp &other) const noexcept
   {
     return nanos_since_epoch_ == other.nanos_since_epoch_;
   }
 
+  /**
+   * @brief Compare two steady time stamps for inequality.
+   *
+   * @return true if the two time stamps are not equal.
+   */
   bool operator!=(const SteadyTimestamp &other) const noexcept
   {
     return nanos_since_epoch_ != other.nanos_since_epoch_;
@@ -102,5 +166,5 @@ class SteadyTimestamp
 private:
   int64_t nanos_since_epoch_;
 };
-}  // namespace core
+}  // namespace common
 OPENTELEMETRY_END_NAMESPACE

api/include/opentelemetry/logs/logger.h

@@ -23,7 +23,7 @@
 #include "opentelemetry/common/attribute_value.h"
 #include "opentelemetry/common/key_value_iterable.h"
 #include "opentelemetry/common/key_value_iterable_view.h"
-#include "opentelemetry/core/timestamp.h"
+#include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/logs/severity.h"
 #include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/nostd/span.h"
@@ -80,7 +80,7 @@ class Logger
                    trace::TraceId trace_id,
                    trace::SpanId span_id,
                    trace::TraceFlags trace_flags,
-                   core::SystemTimestamp timestamp) noexcept = 0;
+                   common::SystemTimestamp timestamp) noexcept = 0;
 
   /*** Overloaded methods for KeyValueIterables ***/
   /**
@@ -101,7 +101,7 @@ class Logger
            trace::TraceId trace_id,
            trace::SpanId span_id,
            trace::TraceFlags trace_flags,
-           core::SystemTimestamp timestamp) noexcept
+           common::SystemTimestamp timestamp) noexcept
   {
     Log(severity, name, body, common::KeyValueIterableView<T>(resource),
         common::KeyValueIterableView<U>(attributes), trace_id, span_id, trace_flags, timestamp);
@@ -115,7 +115,7 @@ class Logger
            trace::TraceId trace_id,
            trace::SpanId span_id,
            trace::TraceFlags trace_flags,
-           core::SystemTimestamp timestamp) noexcept
+           common::SystemTimestamp timestamp) noexcept
   {
     return this->Log(severity, name, body,
                      nostd::span<const std::pair<nostd::string_view, common::AttributeValue>>{

api/include/opentelemetry/logs/noop.h

@@ -24,8 +24,8 @@
 
 #include "opentelemetry/common/attribute_value.h"
 #include "opentelemetry/common/key_value_iterable.h"
+#include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/context/runtime_context.h"
-#include "opentelemetry/core/timestamp.h"
 #include "opentelemetry/logs/logger.h"
 #include "opentelemetry/logs/logger_provider.h"
 #include "opentelemetry/logs/severity.h"
@@ -60,7 +60,7 @@ class NoopLogger final : public Logger
            trace::TraceId trace_id,
            trace::SpanId span_id,
            trace::TraceFlags trace_flags,
-           core::SystemTimestamp timestamp) noexcept override
+           common::SystemTimestamp timestamp) noexcept override
   {}
 };
 

api/include/opentelemetry/plugin/tracer.h

@@ -26,13 +26,13 @@ class Span final : public trace::Span
 
   void AddEvent(nostd::string_view name) noexcept override { span_->AddEvent(name); }
 
-  void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept override
+  void AddEvent(nostd::string_view name, common::SystemTimestamp timestamp) noexcept override
   {
     span_->AddEvent(name, timestamp);
   }
 
   void AddEvent(nostd::string_view name,
-                core::SystemTimestamp timestamp,
+                common::SystemTimestamp timestamp,
                 const common::KeyValueIterable &attributes) noexcept override
   {
     span_->AddEvent(name, timestamp, attributes);

api/include/opentelemetry/trace/default_span.h

@@ -23,10 +23,10 @@ class DefaultSpan : public Span
 
   void AddEvent(nostd::string_view /* name */) noexcept {}
 
-  void AddEvent(nostd::string_view /* name */, core::SystemTimestamp /* timestamp */) noexcept {}
+  void AddEvent(nostd::string_view /* name */, common::SystemTimestamp /* timestamp */) noexcept {}
 
   void AddEvent(nostd::string_view /* name */,
-                core::SystemTimestamp /* timestamp */,
+                common::SystemTimestamp /* timestamp */,
                 const common::KeyValueIterable & /* attributes */) noexcept
   {}
 

api/include/opentelemetry/trace/noop.h

@@ -35,11 +35,12 @@ class NoopSpan final : public Span
 
   void AddEvent(nostd::string_view /*name*/) noexcept override {}
 
-  void AddEvent(nostd::string_view /*name*/, core::SystemTimestamp /*timestamp*/) noexcept override
+  void AddEvent(nostd::string_view /*name*/, 
+		common::SystemTimestamp /*timestamp*/) noexcept override
   {}
 
   void AddEvent(nostd::string_view /*name*/,
-                core::SystemTimestamp /*timestamp*/,
+                common::SystemTimestamp /*timestamp*/,
                 const common::KeyValueIterable & /*attributes*/) noexcept override
   {}
 

api/include/opentelemetry/trace/span.h

@@ -4,7 +4,7 @@
 
 #include "opentelemetry/common/attribute_value.h"
 #include "opentelemetry/common/key_value_iterable_view.h"
-#include "opentelemetry/core/timestamp.h"
+#include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/nostd/span.h"
 #include "opentelemetry/nostd/string_view.h"
@@ -54,8 +54,8 @@ struct StartSpanOptions
   // Span's duration, while timestamps from the system clock can be used to most
   // accurately place a Span's
   // time point relative to other Spans collected across a distributed system.
-  core::SystemTimestamp start_system_time;
-  core::SteadyTimestamp start_steady_time;
+  common::SystemTimestamp start_system_time;
+  common::SteadyTimestamp start_steady_time;
 
   // Explicitly set the parent of a Span.
   //
@@ -75,7 +75,7 @@ struct StartSpanOptions
 struct EndSpanOptions
 {
   // Optionally sets the end time of a Span.
-  core::SteadyTimestamp end_steady_time;
+  common::SteadyTimestamp end_steady_time;
 };
 
 class Tracer;
@@ -109,11 +109,11 @@ class Span
   virtual void AddEvent(nostd::string_view name) noexcept = 0;
 
   // Adds an event to the Span, with a custom timestamp.
-  virtual void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept = 0;
+  virtual void AddEvent(nostd::string_view name, common::SystemTimestamp timestamp) noexcept = 0;
 
   // Adds an event to the Span, with a custom timestamp, and attributes.
   virtual void AddEvent(nostd::string_view name,
-                        core::SystemTimestamp timestamp,
+                        common::SystemTimestamp timestamp,
                         const common::KeyValueIterable &attributes) noexcept = 0;
 
   virtual void AddEvent(nostd::string_view name,
@@ -125,7 +125,7 @@ class Span
   template <class T,
             nostd::enable_if_t<common::detail::is_key_value_iterable<T>::value> * = nullptr>
   void AddEvent(nostd::string_view name,
-                core::SystemTimestamp timestamp,
+                common::SystemTimestamp timestamp,
                 const T &attributes) noexcept
   {
     this->AddEvent(name, timestamp, common::KeyValueIterableView<T>{attributes});
@@ -139,7 +139,7 @@ class Span
   }
 
   void AddEvent(nostd::string_view name,
-                core::SystemTimestamp timestamp,
+                common::SystemTimestamp timestamp,
                 std::initializer_list<std::pair<nostd::string_view, common::AttributeValue>>
                     attributes) noexcept
   {

api/test/core/timestamp_test.cc

@@ -1,9 +1,9 @@
-#include "opentelemetry/core/timestamp.h"
+#include "opentelemetry/common/timestamp.h"
 
 #include <gtest/gtest.h>
 
-using opentelemetry::core::SteadyTimestamp;
-using opentelemetry::core::SystemTimestamp;
+using opentelemetry::common::SteadyTimestamp;
+using opentelemetry::common::SystemTimestamp;
 
 template <class Timestamp>
 static bool AreNearlyEqual(const Timestamp &t1, const Timestamp &t2) noexcept

api/test/logs/logger_test.cc

@@ -1,7 +1,7 @@
 #include <gtest/gtest.h>
 #include <array>
 
-#include "opentelemetry/core/timestamp.h"
+#include "opentelemetry/common/timestamp.h"
 #include "opentelemetry/logs/logger.h"
 #include "opentelemetry/logs/provider.h"
 #include "opentelemetry/nostd/shared_ptr.h"
@@ -77,7 +77,7 @@ class TestLogger : public Logger
            opentelemetry::trace::TraceId trace_id,
            opentelemetry::trace::SpanId span_id,
            opentelemetry::trace::TraceFlags trace_flags,
-           opentelemetry::core::SystemTimestamp timestamp) noexcept override
+           opentelemetry::common::SystemTimestamp timestamp) noexcept override
   {}
 };
 

api/test/trace/noop_test.cc

@@ -1,13 +1,13 @@
 #include "opentelemetry/trace/noop.h"
-#include "opentelemetry/core/timestamp.h"
+#include "opentelemetry/common/timestamp.h"
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include <gtest/gtest.h>
 
-using opentelemetry::core::SystemTimestamp;
+using opentelemetry::common::SystemTimestamp;
 using opentelemetry::trace::NoopTracer;
 using opentelemetry::trace::SpanContext;
 using opentelemetry::trace::Tracer;