Resource sdk Implementation

sdk/include/opentelemetry/sdk/resource/resource.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include "opentelemetry/sdk/common/attribute_utils.h"
+#include "opentelemetry/sdk/resource/resource_detector.h"
+#include "opentelemetry/sdk/version/version.h"
+#include "opentelemetry/version.h"
+
+#include <cstdlib>
+#include <memory>
+#include <sstream>
+#include <unordered_map>
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace resource
+{
+
+using ResourceAttributes =
+    std::unordered_map<std::string, opentelemetry::sdk::common::OwnedAttributeValue>;
+
+class Resource
+{
+public:
+  const ResourceAttributes &GetAttributes() const noexcept;
+
+  /**
+   * Returns a new, merged {@link Resource} by merging the current Resource
+   * with the other Resource. In case of a collision, current Resource takes
+   * precedence.
+   *
+   * @param other the Resource that will be merged with this.
+   * @returns the newly merged Resource.
+   */
+
+  std::shared_ptr<Resource> Merge(const Resource &other) noexcept;
+
+  /**
+   * Returns a newly created Resource with the specified attributes.
+   * It adds (merge) SDK attributes and OTEL attributes before returning.
+   * @param attributes for this resource
+   * @returns the newly created Resource.
+   */
+
+  static std::shared_ptr<Resource> Create(const ResourceAttributes &attributes);
+
+  /**
+   * Returns an Empty resource.
+   */
+
+  static Resource &GetEmpty();
+
+  /**
+   * Returns a Resource that indentifies the SDK in use.
+   */
+
+  static Resource &GetDefault();
+
+protected:
+  /**
+   * The constructor is private and only for use internally by the class and
+   * inside ResourceDetector class.
+   * Users should use the Create factory method to obtain a Resource
+   * instance.
+   */
+  Resource(const ResourceAttributes &attributes = ResourceAttributes()) noexcept;
+
+private:
+  ResourceAttributes attributes_;
+
+  friend class OTELResourceDetector;
+};
+
+}  // namespace resource
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/include/opentelemetry/sdk/resource/resource_detector.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "opentelemetry/nostd/unique_ptr.h"
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace resource
+{
+
+class Resource;
+
+/**
+ * Interface for a Resource Detector
+ */
+class ResourceDetector
+{
+public:
+  virtual std::shared_ptr<Resource> Detect() = 0;
+};
+
+/**
+ * OTelResourceDetector to detect the presence of and create a Resource
+ * from the OTEL_RESOURCE_ATTRIBUTES environment variable.
+ */
+class OTELResourceDetector : public ResourceDetector
+{
+public:
+  std::shared_ptr<Resource> Detect() noexcept override;
+};
+
+}  // namespace resource
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/src/CMakeLists.txt

@@ -3,3 +3,4 @@ add_subdirectory(trace)
 add_subdirectory(metrics)
 add_subdirectory(logs)
 add_subdirectory(version)
+add_subdirectory(resource)

sdk/src/resource/BUILD

@@ -0,0 +1,26 @@
+# Copyright 2020, OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "resource",
+    srcs = glob(["**/*.cc"]),
+    hdrs = glob(["**/*.h"]),
+    include_prefix = "src/resource",
+    deps = [
+        "//api",
+        "//sdk:headers",
+    ],
+)

sdk/src/resource/CMakeLists.txt

@@ -0,0 +1,16 @@
+add_library(opentelemetry_resources resource.cc resource_detector.cc)
+
+set_target_properties(opentelemetry_resources PROPERTIES EXPORT_NAME resources)
+
+target_link_libraries(opentelemetry_resources opentelemetry_common)
+
+target_include_directories(
+  opentelemetry_resources
+  PUBLIC "$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/sdk/include>")
+
+install(
+  TARGETS opentelemetry_resources
+  EXPORT "${PROJECT_NAME}-target"
+  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})

sdk/src/resource/resource.cc

@@ -0,0 +1,69 @@
+#include "opentelemetry/sdk/resource/resource.h"
+#include "opentelemetry/nostd/span.h"
+#include "opentelemetry/sdk/resource/resource_detector.h"
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace resource
+{
+
+const std::string TELEMETRY_SDK_LANGUAGE = "telemetry.sdk.language";
+const std::string TELEMETRY_SDK_NAME     = "telemetry.sdk.name";
+const std::string TELEMETRY_SDK_VERSION  = "telemetry.sdk.version";
+
+Resource::Resource(const ResourceAttributes &attributes) noexcept : attributes_(attributes) {}
+
+std::shared_ptr<Resource> Resource::Merge(const Resource &other) noexcept
+{
+  ResourceAttributes merged_resource_attributes(attributes_);
+  for (auto &elem : other.attributes_)
+  {
+    if ((merged_resource_attributes.find(elem.first) == merged_resource_attributes.end()) ||
+        (nostd::holds_alternative<std::string>(attributes_[elem.first]) &&
+         nostd::get<std::string>(attributes_[elem.first]).size() == 0))
+    {
+      merged_resource_attributes[elem.first] = elem.second;
+    }
+  }
+  return std::make_shared<Resource>(Resource(merged_resource_attributes));
+}
+
+std::shared_ptr<Resource> Resource::Create(const ResourceAttributes &attributes)
+{
+  static auto otel_resource = OTELResourceDetector().Detect();
+  auto default_resource     = Resource::GetDefault();
+  // auto otel_resource    = OTELResourceDetector().Detect();
+
+  if (attributes.size() > 0)
+  {
+    Resource tmp_resource(attributes);
+    auto merged_resource = tmp_resource.Merge(default_resource);
+    return merged_resource->Merge(*otel_resource);
+  }
+  return default_resource.Merge(*otel_resource);
+}
+
+Resource &Resource::GetEmpty()
+{
+  static Resource empty_resource;
+  return empty_resource;
+}
+
+Resource &Resource::GetDefault()
+{
+  static Resource default_resource({{TELEMETRY_SDK_LANGUAGE, "cpp"},
+                                    {TELEMETRY_SDK_NAME, "opentelemetry"},
+                                    {TELEMETRY_SDK_VERSION, OPENTELEMETRY_SDK_VERSION}});
+  return default_resource;
+}
+
+const ResourceAttributes &Resource::GetAttributes() const noexcept
+{
+  return attributes_;
+}
+
+}  // namespace resource
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/src/resource/resource_detector.cc

@@ -0,0 +1,34 @@
+#include "opentelemetry/sdk/resource/resource_detector.h"
+#include <cstdlib>
+#include "opentelemetry/sdk/resource/resource.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace resource
+{
+
+const char *OTEL_RESOURCE_ATTRIBUTES = "OTEL_RESOURCE_ATTRIBUTES";
+
+std::shared_ptr<Resource> OTELResourceDetector::Detect() noexcept
+{
+  char *attributes_str = std::getenv(OTEL_RESOURCE_ATTRIBUTES);
+  if (attributes_str == nullptr)
+    return std::make_shared<Resource>(Resource());
+  // return Resource::GetEmpty();
+  ResourceAttributes attributes;
+  std::istringstream iss(attributes_str);
+  std::string token;
+  while (std::getline(iss, token, ','))
+  {
+    size_t pos        = token.find('=');
+    std::string key   = token.substr(0, pos);
+    std::string value = token.substr(pos + 1);
+    attributes[key]   = value;
+  }
+  return std::make_shared<Resource>(Resource(attributes));
+}
+
+}  // namespace resource
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

sdk/test/CMakeLists.txt

@@ -2,3 +2,4 @@ add_subdirectory(common)
 add_subdirectory(trace)
 add_subdirectory(metrics)
 add_subdirectory(logs)
+add_subdirectory(resource)

sdk/test/resource/BUILD

@@ -0,0 +1,11 @@
+cc_test(
+    name = "resource_test",
+    srcs = [
+        "resource_test.cc",
+    ],
+    deps = [
+        "//api",
+        "//sdk/src/resource",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

sdk/test/resource/CMakeLists.txt

@@ -0,0 +1,9 @@
+foreach(testname resource_test)
+  add_executable(${testname} "${testname}.cc")
+  target_link_libraries(${testname} ${GTEST_BOTH_LIBRARIES}
+                        ${CMAKE_THREAD_LIBS_INIT} opentelemetry_resources)
+  gtest_add_tests(
+    TARGET ${testname}
+    TEST_PREFIX resources.
+    TEST_LIST ${testname})
+endforeach()