[API] Add Enabled method to Tracer

api/include/opentelemetry/plugin/tracer.h

@@ -87,7 +87,11 @@ class Tracer final : public trace::Tracer, public std::enable_shared_from_this<T
   Tracer(std::shared_ptr<DynamicLibraryHandle> library_handle,
          std::unique_ptr<TracerHandle> &&tracer_handle) noexcept
       : library_handle_{std::move(library_handle)}, tracer_handle_{std::move(tracer_handle)}
-  {}
+  {
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+    UpdateEnabled(true);
+#endif
+  }
 
   // trace::Tracer
   nostd::shared_ptr<trace::Span> StartSpan(
@@ -104,10 +108,6 @@ class Tracer final : public trace::Tracer, public std::enable_shared_from_this<T
     return nostd::shared_ptr<trace::Span>{new (std::nothrow) Span{this->shared_from_this(), span}};
   }
 
-#if OPENTELEMETRY_ABI_VERSION_NO >= 2
-  bool Enabled() const noexcept override { return true; }
-#endif
-
 #if OPENTELEMETRY_ABI_VERSION_NO == 1
 
   void ForceFlushWithMicroseconds(uint64_t timeout) noexcept override

api/include/opentelemetry/trace/noop.h

@@ -96,6 +96,13 @@ class OPENTELEMETRY_EXPORT NoopTracer final : public Tracer,
 {
 public:
   // Tracer
+  NoopTracer()
+  {
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+    UpdateEnabled(false);
+#endif
+  }
+
   nostd::shared_ptr<Span> StartSpan(nostd::string_view /*name*/,
                                     const common::KeyValueIterable & /*attributes*/,
                                     const SpanContextKeyValueIterable & /*links*/,
@@ -108,10 +115,6 @@ class OPENTELEMETRY_EXPORT NoopTracer final : public Tracer,
     return noop_span;
   }
 
-#if OPENTELEMETRY_ABI_VERSION_NO >= 2
-  bool Enabled() const noexcept override { return false; }
-#endif
-
 #if OPENTELEMETRY_ABI_VERSION_NO == 1
 
   void ForceFlushWithMicroseconds(uint64_t /*timeout*/) noexcept override {}

api/include/opentelemetry/trace/tracer.h

@@ -172,7 +172,7 @@ class Tracer
    *
    * @since ABI_VERSION 2
    */
-  virtual bool Enabled() const noexcept = 0;
+  bool Enabled() const noexcept { return this->enabled_; }
 #endif
 
 #if OPENTELEMETRY_ABI_VERSION_NO == 1
@@ -209,6 +209,30 @@ class Tracer
   virtual void CloseWithMicroseconds(uint64_t timeout) noexcept = 0;
 
 #endif /* OPENTELEMETRY_ABI_VERSION_NO */
+
+protected:
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+
+  /**
+   * Updates the enabled state of the tracer. Calling this method will affect the result of the
+   * subsequent calls to {@code opentelemetry::v2::trace::Tracer::Enabled()}.
+   *
+   * This method should be used by SDK implementations to indicate the tracer's updated state
+   * whenever a tracer transitions from enabled to disabled state and vice versa.
+   *
+   * @param enabled The new state of the tracer. False would indicate that the tracer is no longer
+   * enabled and will not produce as
+   *
+   * @since ABI_VERSION 2
+   */
+  void UpdateEnabled(const bool enabled) noexcept { this->enabled_ = enabled; }
+#endif
+
+private:
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  // variable to support implementation of Enabled method introduced in ABI V2.
+  bool enabled_ = true;
+#endif
 };
 }  // namespace trace
 OPENTELEMETRY_END_NAMESPACE

api/test/singleton/singleton_test.cc

@@ -169,6 +169,13 @@ void reset_counts()
 class MyTracer : public trace::Tracer
 {
 public:
+  MyTracer()
+  {
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+    UpdateEnabled(true);
+#endif
+  }
+
   nostd::shared_ptr<trace::Span> StartSpan(
       nostd::string_view name,
       const common::KeyValueIterable & /* attributes */,
@@ -285,12 +292,6 @@ class MyTracer : public trace::Tracer
     return result;
   }
 
-#if OPENTELEMETRY_ABI_VERSION_NO >= 2
-
-  bool Enabled() const noexcept override { return true; }
-
-#endif
-
 #if OPENTELEMETRY_ABI_VERSION_NO == 1
 
   void ForceFlushWithMicroseconds(uint64_t /* timeout */) noexcept override {}

examples/plugin/plugin/tracer.cc

@@ -81,7 +81,12 @@ class Span final : public trace::Span
 };
 }  // namespace
 
-Tracer::Tracer(nostd::string_view /*output*/) {}
+Tracer::Tracer(nostd::string_view /*output*/)
+{
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  UpdateEnabled(true);
+#endif
+}
 
 nostd::shared_ptr<trace::Span> Tracer::StartSpan(nostd::string_view name,
                                                  const common::KeyValueIterable &attributes,
@@ -91,10 +96,3 @@ nostd::shared_ptr<trace::Span> Tracer::StartSpan(nostd::string_view name,
   return nostd::shared_ptr<trace::Span>{
       new (std::nothrow) Span{this->shared_from_this(), name, attributes, links, options}};
 }
-
-#if OPENTELEMETRY_ABI_VERSION_NO >= 2
-bool Tracer::Enabled() const noexcept
-{
-  return true;
-}
-#endif

examples/plugin/plugin/tracer.h

@@ -26,12 +26,6 @@ class Tracer final : public opentelemetry::trace::Tracer,
       const opentelemetry::trace::SpanContextKeyValueIterable & /*links*/,
       const opentelemetry::trace::StartSpanOptions & /*options */) noexcept override;
 
-#if OPENTELEMETRY_ABI_VERSION_NO >= 2
-
-  bool Enabled() const noexcept override;
-
-#endif
-
 #if OPENTELEMETRY_ABI_VERSION_NO == 1
 
   void ForceFlushWithMicroseconds(uint64_t /*timeout*/) noexcept override {}

sdk/include/opentelemetry/sdk/trace/tracer.h

@@ -71,8 +71,6 @@ class Tracer final : public opentelemetry::trace::Tracer,
   }
 
   void CloseWithMicroseconds(uint64_t timeout) noexcept;
-
-  bool Enabled() const noexcept override;
 #else
   /* Exposed in the API in ABI version 1, but does not belong to the API */
   void ForceFlushWithMicroseconds(uint64_t timeout) noexcept override;

sdk/src/trace/tracer.cc

@@ -46,7 +46,11 @@ Tracer::Tracer(std::shared_ptr<TracerContext> context,
     : instrumentation_scope_{std::move(instrumentation_scope)},
       context_{std::move(context)},
       tracer_config_(context_->GetTracerConfigurator().ComputeConfig(*instrumentation_scope_))
-{}
+{
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  UpdateEnabled(tracer_config_.IsEnabled());
+#endif
+}
 
 nostd::shared_ptr<opentelemetry::trace::Span> Tracer::StartSpan(
     nostd::string_view name,
@@ -163,13 +167,6 @@ nostd::shared_ptr<opentelemetry::trace::Span> Tracer::StartSpan(
   }
 }
 
-#if OPENTELEMETRY_ABI_VERSION_NO >= 2
-bool Tracer::Enabled() const noexcept
-{
-  return tracer_config_.IsEnabled();
-}
-#endif
-
 void Tracer::ForceFlushWithMicroseconds(uint64_t timeout) noexcept
 {
   if (context_)