[Exporter] Group spans by resource and instrumentation scope in OTLP export requests

exporters/otlp/include/opentelemetry/exporters/otlp/otlp_recordable.h

@@ -27,7 +27,10 @@ class OtlpRecordable final : public opentelemetry::sdk::trace::Recordable
   /** Dynamically converts the resource of this span into a proto. */
   proto::resource::v1::Resource ProtoResource() const noexcept;
 
+  const opentelemetry::sdk::resource::Resource *GetResource() const noexcept;
   const std::string GetResourceSchemaURL() const noexcept;
+  const opentelemetry::sdk::instrumentationscope::InstrumentationScope *GetInstrumentationScope()
+      const noexcept;
   const std::string GetInstrumentationLibrarySchemaURL() const noexcept;
 
   proto::common::v1::InstrumentationScope GetProtoInstrumentationScope() const noexcept;

exporters/otlp/src/otlp_recordable.cc

@@ -40,6 +40,11 @@ proto::resource::v1::Resource OtlpRecordable::ProtoResource() const noexcept
   return proto;
 }
 
+const opentelemetry::sdk::resource::Resource *OtlpRecordable::GetResource() const noexcept
+{
+  return resource_;
+}
+
 const std::string OtlpRecordable::GetResourceSchemaURL() const noexcept
 {
   std::string schema_url;
@@ -51,6 +56,12 @@ const std::string OtlpRecordable::GetResourceSchemaURL() const noexcept
   return schema_url;
 }
 
+const opentelemetry::sdk::instrumentationscope::InstrumentationScope *
+OtlpRecordable::GetInstrumentationScope() const noexcept
+{
+  return instrumentation_scope_;
+}
+
 const std::string OtlpRecordable::GetInstrumentationLibrarySchemaURL() const noexcept
 {
   std::string schema_url;

exporters/otlp/src/otlp_recordable_utils.cc

@@ -56,19 +56,54 @@ void OtlpRecordableUtils::PopulateRequest(
     return;
   }
 
+  using spans_by_scope =
+      std::unordered_map<const opentelemetry::sdk::instrumentationscope::InstrumentationScope *,
+                         std::vector<std::unique_ptr<OtlpRecordable>>>;
+  std::unordered_map<const opentelemetry::sdk::resource::Resource *, spans_by_scope> spans_index;
+
+  // Collect spans per resource and instrumentation scope
   for (auto &recordable : spans)
   {
     auto rec = std::unique_ptr<OtlpRecordable>(static_cast<OtlpRecordable *>(recordable.release()));
-    auto resource_span = request->add_resource_spans();
-    auto scope_spans   = resource_span->add_scope_spans();
+    auto resource        = rec->GetResource();
+    auto instrumentation = rec->GetInstrumentationScope();
 
-    *scope_spans->add_spans()     = std::move(rec->span());
-    *scope_spans->mutable_scope() = rec->GetProtoInstrumentationScope();
+    spans_index[resource][instrumentation].emplace_back(std::move(rec));
+  }
 
-    scope_spans->set_schema_url(rec->GetInstrumentationLibrarySchemaURL());
+  // Add all resource spans
+  for (auto &input_resource_spans : spans_index)
+  {
+    // Add the resource
+    auto resource_spans = request->add_resource_spans();
+    if (input_resource_spans.first)
+    {
+      proto::resource::v1::Resource resource_proto;
+      OtlpPopulateAttributeUtils::PopulateAttribute(&resource_proto, *input_resource_spans.first);
+      *resource_spans->mutable_resource() = resource_proto;
+      resource_spans->set_schema_url(input_resource_spans.first->GetSchemaURL());
+    }
 
-    *resource_span->mutable_resource() = rec->ProtoResource();
-    resource_span->set_schema_url(rec->GetResourceSchemaURL());
+    // Add all scope spans
+    for (auto &input_scope_spans : input_resource_spans.second)
+    {
+      // Add the instrumentation scope
+      auto scope_spans = resource_spans->add_scope_spans();
+      if (input_scope_spans.first)
+      {
+        proto::common::v1::InstrumentationScope instrumentation_scope_proto;
+        instrumentation_scope_proto.set_name(input_scope_spans.first->GetName());
+        instrumentation_scope_proto.set_version(input_scope_spans.first->GetVersion());
+        *scope_spans->mutable_scope() = instrumentation_scope_proto;
+        scope_spans->set_schema_url(input_scope_spans.first->GetSchemaURL());
+      }
+
+      // Add all spans to this scope spans
+      for (auto &input_span : input_scope_spans.second)
+      {
+        *scope_spans->add_spans() = std::move(input_span->span());
+      }
+    }
   }
 }
 

exporters/otlp/test/otlp_recordable_test.cc

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #include "opentelemetry/exporters/otlp/otlp_recordable.h"
+#include "opentelemetry/exporters/otlp/otlp_recordable_utils.h"
 #include "opentelemetry/sdk/resource/resource.h"
 
 #if defined(__GNUC__)
@@ -285,6 +286,93 @@ TEST(OtlpRecordable, SetArrayAttribute)
   }
 }
 
+// Test otlp resource populate request util
+TEST(OtlpRecordable, PopulateRequest)
+{
+  auto rec1      = std::unique_ptr<sdk::trace::Recordable>(new OtlpRecordable);
+  auto resource1 = resource::Resource::Create({{"service.name", "one"}});
+  rec1->SetResource(resource1);
+  auto inst_lib1 = trace_sdk::InstrumentationScope::Create("one", "1");
+  rec1->SetInstrumentationScope(*inst_lib1);
+
+  auto rec2      = std::unique_ptr<sdk::trace::Recordable>(new OtlpRecordable);
+  auto resource2 = resource::Resource::Create({{"service.name", "two"}});
+  rec2->SetResource(resource2);
+  auto inst_lib2 = trace_sdk::InstrumentationScope::Create("two", "2");
+  rec2->SetInstrumentationScope(*inst_lib2);
+
+  // This has the same resource as rec2, but a different scope
+  auto rec3 = std::unique_ptr<sdk::trace::Recordable>(new OtlpRecordable);
+  rec3->SetResource(resource2);
+  auto inst_lib3 = trace_sdk::InstrumentationScope::Create("three", "3");
+  rec3->SetInstrumentationScope(*inst_lib3);
+
+  proto::collector::trace::v1::ExportTraceServiceRequest req;
+  std::vector<std::unique_ptr<sdk::trace::Recordable>> spans;
+  spans.push_back(std::move(rec1));
+  spans.push_back(std::move(rec2));
+  spans.push_back(std::move(rec3));
+  const nostd::span<std::unique_ptr<sdk::trace::Recordable>, 3> spans_span(spans.data(), 3);
+  OtlpRecordableUtils::PopulateRequest(spans_span, &req);
+
+  EXPECT_EQ(req.resource_spans().size(), 2);
+  for (auto resource_spans : req.resource_spans())
+  {
+    auto service_name     = resource_spans.resource().attributes(0).value().string_value();
+    auto scope_spans_size = resource_spans.scope_spans().size();
+    if (service_name == "one")
+    {
+      EXPECT_EQ(scope_spans_size, 1);
+      EXPECT_EQ(resource_spans.scope_spans(0).scope().name(), "one");
+    }
+    if (service_name == "two")
+    {
+      EXPECT_EQ(scope_spans_size, 2);
+    }
+  }
+}
+
+// Test otlp resource populate request util with missing data
+TEST(OtlpRecordable, PopulateRequestMissing)
+{
+  // Missing scope
+  auto rec1      = std::unique_ptr<sdk::trace::Recordable>(new OtlpRecordable);
+  auto resource1 = resource::Resource::Create({{"service.name", "one"}});
+  rec1->SetResource(resource1);
+
+  // Missing resource
+  auto rec2      = std::unique_ptr<sdk::trace::Recordable>(new OtlpRecordable);
+  auto inst_lib2 = trace_sdk::InstrumentationScope::Create("two", "2");
+  rec2->SetInstrumentationScope(*inst_lib2);
+
+  proto::collector::trace::v1::ExportTraceServiceRequest req;
+  std::vector<std::unique_ptr<sdk::trace::Recordable>> spans;
+  spans.push_back(std::move(rec1));
+  spans.push_back(std::move(rec2));
+  const nostd::span<std::unique_ptr<sdk::trace::Recordable>, 2> spans_span(spans.data(), 2);
+  OtlpRecordableUtils::PopulateRequest(spans_span, &req);
+
+  EXPECT_EQ(req.resource_spans().size(), 2);
+  for (auto resource_spans : req.resource_spans())
+  {
+    // Both should have scope spans
+    EXPECT_EQ(resource_spans.scope_spans().size(), 1);
+    auto scope = resource_spans.scope_spans(0).scope();
+    // Select the one with missing scope
+    if (scope.name() == "")
+    {
+      // Version is also empty
+      EXPECT_EQ(scope.version(), "");
+    }
+    else
+    {
+      // The other has a name and version
+      EXPECT_EQ(scope.name(), "two");
+      EXPECT_EQ(scope.version(), "2");
+    }
+  }
+}
+
 template <typename T>
 struct EmptyArrayAttributeTest : public testing::Test
 {