add api method to check if tracer is enabled

Author: psx95

api/include/opentelemetry/trace/noop.h

@@ -108,6 +108,10 @@ class OPENTELEMETRY_EXPORT NoopTracer final : public Tracer,
     return noop_span;
   }
 
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  bool IsEnabled() 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

@@ -163,6 +163,15 @@ class Tracer
     }
   }
 
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  /**
+   * Returns a boolean indicating if the tracer is enabled or not. Disabled tracers behave like
+   * no-op tracers. By default, tracers are considered enabled.
+   * @return true if the tracer is enabled, false otherwise.
+   */
+  virtual bool IsEnabled() const noexcept = 0;
+#endif
+
 #if OPENTELEMETRY_ABI_VERSION_NO == 1
 
   /*

api/test/trace/tracer_test.cc

@@ -40,3 +40,13 @@ TEST(TracerTest, GetCurrentSpan)
   current = tracer->GetCurrentSpan();
   ASSERT_FALSE(current->GetContext().IsValid());
 }
+
+TEST(TracerTest, IsEnabled)
+{
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  std::unique_ptr<trace_api::Tracer> tracer(new trace_api::NoopTracer());
+  ASSERT_FALSE(tracer->IsEnabled());
+#else
+  GTEST_SKIP() << "IsEnabled() not exposed in ABI v1";
+#endif
+}

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

@@ -71,6 +71,8 @@ class Tracer final : public opentelemetry::trace::Tracer,
   }
 
   void CloseWithMicroseconds(uint64_t timeout) noexcept;
+
+  bool IsEnabled() 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;
@@ -109,6 +111,9 @@ class Tracer final : public opentelemetry::trace::Tracer,
   std::shared_ptr<InstrumentationScope> instrumentation_scope_;
   std::shared_ptr<TracerContext> context_;
   static const std::shared_ptr<opentelemetry::trace::NoopTracer> kNoopTracer;
+
+  // Provides IsEnabled implementation for Tracers, appropriate for current ABI version
+  bool ABIAppropriateIsEnabled() const;
 };
 }  // namespace trace
 }  // namespace sdk

sdk/src/trace/tracer.cc

@@ -58,7 +58,7 @@ nostd::shared_ptr<opentelemetry::trace::Span> Tracer::StartSpan(
   opentelemetry::trace::SpanContext parent_context = GetCurrentSpan()->GetContext();
   if (nostd::holds_alternative<opentelemetry::trace::SpanContext>(options.parent))
   {
-    if (!tracer_config_->IsEnabled())
+    if (!ABIAppropriateIsEnabled())
     {
       return kNoopTracer->StartSpan(name, attributes, links, options);
     }
@@ -164,6 +164,22 @@ nostd::shared_ptr<opentelemetry::trace::Span> Tracer::StartSpan(
   }
 }
 
+bool Tracer::ABIAppropriateIsEnabled() const
+{
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+  return Tracer::IsEnabled();
+#else
+  return tracer_config_->IsEnabled();
+#endif
+}
+
+#if OPENTELEMETRY_ABI_VERSION_NO >= 2
+bool Tracer::IsEnabled() const noexcept
+{
+  return tracer_config_->IsEnabled();
+}
+#endif
+
 void Tracer::ForceFlushWithMicroseconds(uint64_t timeout) noexcept
 {
   if (context_)