Fix for resource deletion after tracer provider shutdown (#911)

Author: lalitb

examples/batch/main.cc

@@ -31,11 +31,15 @@ void initTracer()
   // We export `kNumSpans` after every `schedule_delay_millis` milliseconds.
   options.max_export_batch_size = kNumSpans;
 
+  opentelemetry::sdk::resource::ResourceAttributes attributes = {{"service", "test_service"},
+                                                                 {"version", (uint32_t)1}};
+  auto resource = opentelemetry::sdk::resource::Resource::Create(attributes);
+
   auto processor = std::unique_ptr<sdktrace::SpanProcessor>(
       new sdktrace::BatchSpanProcessor(std::move(exporter), options));
 
   auto provider = nostd::shared_ptr<opentelemetry::trace::TracerProvider>(
-      new sdktrace::TracerProvider(std::move(processor)));
+      new sdktrace::TracerProvider(std::move(processor), resource));
   // Set the global trace provider.
   opentelemetry::trace::Provider::SetTracerProvider(provider);
 }

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

@@ -60,8 +60,10 @@ class Tracer final : public trace_api::Tracer, public std::enable_shared_from_th
   Sampler &GetSampler() { return context_->GetSampler(); }
 
 private:
-  std::shared_ptr<sdk::trace::TracerContext> context_;
+  // order of declaration is important here - instrumentation library should destroy after
+  // tracer-context.
   std::shared_ptr<InstrumentationLibrary> instrumentation_library_;
+  std::shared_ptr<sdk::trace::TracerContext> context_;
 };
 }  // namespace trace
 }  // namespace sdk

sdk/include/opentelemetry/sdk/trace/tracer_context.h

@@ -88,11 +88,11 @@ class TracerContext
   bool Shutdown() noexcept;
 
 private:
-  // This is an atomic pointer so we can adapt the processor pipeline dynamically.
-  std::unique_ptr<SpanProcessor> processor_;
+  //  order of declaration is important here - resource object should be destroyed after processor.
   opentelemetry::sdk::resource::Resource resource_;
   std::unique_ptr<Sampler> sampler_;
   std::unique_ptr<IdGenerator> id_generator_;
+  std::unique_ptr<SpanProcessor> processor_;
 };
 
 }  // namespace trace

sdk/include/opentelemetry/sdk/trace/tracer_provider.h

@@ -96,8 +96,9 @@ class TracerProvider final : public opentelemetry::trace::TracerProvider
   bool ForceFlush(std::chrono::microseconds timeout = (std::chrono::microseconds::max)()) noexcept;
 
 private:
-  std::shared_ptr<sdk::trace::TracerContext> context_;
+  // order of declaration is important here - tracers should destroy only after context.
   std::vector<std::shared_ptr<opentelemetry::sdk::trace::Tracer>> tracers_;
+  std::shared_ptr<sdk::trace::TracerContext> context_;
   std::mutex lock_;
 };
 }  // namespace trace

sdk/src/trace/tracer.cc

@@ -18,7 +18,7 @@ namespace trace
 
 Tracer::Tracer(std::shared_ptr<sdk::trace::TracerContext> context,
                std::unique_ptr<InstrumentationLibrary> instrumentation_library) noexcept
-    : context_{context}, instrumentation_library_{std::move(instrumentation_library)}
+    : instrumentation_library_{std::move(instrumentation_library)}, context_{context}
 {}
 
 nostd::shared_ptr<trace_api::Span> Tracer::StartSpan(

sdk/src/trace/tracer_context.cc

@@ -14,10 +14,10 @@ TracerContext::TracerContext(std::vector<std::unique_ptr<SpanProcessor>> &&proce
                              opentelemetry::sdk::resource::Resource resource,
                              std::unique_ptr<Sampler> sampler,
                              std::unique_ptr<IdGenerator> id_generator) noexcept
-    : processor_(std::unique_ptr<SpanProcessor>(new MultiSpanProcessor(std::move(processors)))),
-      resource_(resource),
+    : resource_(resource),
       sampler_(std::move(sampler)),
-      id_generator_(std::move(id_generator))
+      id_generator_(std::move(id_generator)),
+      processor_(std::unique_ptr<SpanProcessor>(new MultiSpanProcessor(std::move(processors))))
 {}
 
 Sampler &TracerContext::GetSampler() const noexcept