Using STD library for API surface

.github/workflows/ci.yml

@@ -163,6 +163,16 @@ jobs:
     - name: run tests
       run: ./ci/do_ci.sh bazel.tsan
 
+  bazel_osx:
+    name: Bazel on MacOS
+    runs-on: macos-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: 'recursive'
+    - name: run tests
+      run: ./ci/do_ci.sh bazel.test
+
   benchmark:
     name: Benchmark
     runs-on: ubuntu-latest
@@ -195,15 +205,6 @@ jobs:
     - name: run tests
       run: ./ci/do_ci.sh format
 
-  osx_test:
-    name: Bazel on MacOS
-    runs-on: macos-latest
-    steps:
-    - uses: actions/checkout@v2
-      with:
-        submodules: 'recursive'
-    - name: run tests
-      run: ./ci/do_ci.sh bazel.test
 
   windows:
     name: CMake -> exporter proto

CMakeLists.txt

@@ -10,6 +10,48 @@ if(NOT DEFINED CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 11)
 endif()
 
+option(WITH_STL "Whether to use Standard Library for C++latest features" OFF)
+
+option(WITH_ABSEIL "Whether to use Abseil for C++latest features" OFF)
+
+if(WITH_ABSEIL)
+  add_definitions(-DHAVE_ABSEIL)
+  find_package(absl CONFIG REQUIRED)
+
+  # Abseil headers-only lib is needed for absl::variant to work vs2015.
+  # `nostd::mpark::variant` is not compiling in vs2015.
+  set(CORE_RUNTIME_LIBS absl::any absl::base absl::bits absl::city)
+
+  # target_link_libraries(main PRIVATE absl::any absl::base absl::bits
+  # absl::city)
+endif()
+
+if(WITH_STL)
+  # Require at least C++17. C++20 is needed to avoid gsl::span
+  add_definitions(-DHAVE_CPP_STDLIB -DHAVE_GSL)
+
+  if(CMAKE_MINOR_VERSION VERSION_GREATER "3.18")
+    # Ask for 20, may get anything below
+    set(CMAKE_CXX_STANDARD 20)
+  else()
+    # Ask for 17, may get anything below
+    set(CMAKE_CXX_STANDARD 17)
+  endif()
+
+  # Guidelines Support Library path. Used if we are not on not get C++20.
+  #
+  # TODO: respect WITH_ABSEIL as alternate implementation of std::span
+  set(GSL_DIR third_party/ms-gsl)
+  include_directories(${GSL_DIR}/include)
+
+  # Optimize for speed to reduce the hops
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    set(CMAKE_CXX_FLAGS_SPEED "/O2")
+    set(CMAKE_CXX_FLAGS
+        "${CMAKE_CXX_FLAGS} /Zc:__cplusplus ${CMAKE_CXX_FLAGS_SPEED}")
+  endif()
+endif()
+
 option(WITH_OTLP "Whether to include the OpenTelemetry Protocol in the SDK" OFF)
 
 option(WITH_PROMETHEUS "Whether to include the Prometheus Client in the SDK"

CMakeSettings.json

@@ -46,6 +46,63 @@
                     "type": "BOOL"
                 }
             ]
+        },
+        {
+            "name": "stdlib-x64-Debug",
+            "generator": "Ninja",
+            "configurationType": "Debug",
+            "inheritEnvironments": [ "msvc_x64_x64" ],
+            "buildRoot": "${projectDir}\\out\\vs2019\\${name}",
+            "installRoot": "${projectDir}\\out\\vs2019\\${name}\\install",
+            "cmakeCommandArgs": "",
+            "buildCommandArgs": "",
+            "ctestCommandArgs": "",
+            "variables": [
+                {
+                    "name": "WITH_STL",
+                    "value": "True",
+                    "type": "BOOL"
+                },
+                {
+                    "name": "WITH_OTLP",
+                    "value": "True",
+                    "type": "BOOL"
+                },
+                {
+                    "name": "WITH_EXAMPLES",
+                    "value": "true",
+                    "type": "BOOL"
+                }
+            ]
+        },
+        {
+            "name": "stdlib-x64-Release",
+            "generator": "Ninja",
+            "configurationType": "RelWithDebInfo",
+            "inheritEnvironments": [ "msvc_x64_x64" ],
+            "buildRoot": "${projectDir}\\out\\vs2019\\${name}",
+            "installRoot": "${projectDir}\\out\\vs2019\\${name}\\install",
+            "cmakeCommandArgs": "",
+            "buildCommandArgs": "",
+            "ctestCommandArgs": "",
+            "cmakeToolchain": "",
+            "variables": [
+                {
+                    "name": "WITH_STL",
+                    "value": "True",
+                    "type": "BOOL"
+                },
+                {
+                    "name": "WITH_OTLP",
+                    "value": "True",
+                    "type": "BOOL"
+                },
+                {
+                    "name": "WITH_EXAMPLES",
+                    "value": "true",
+                    "type": "BOOL"
+                }
+            ]
         }
     ]
 }

api/CMakeLists.txt

@@ -12,3 +12,9 @@ install(
 if(BUILD_TESTING)
   add_subdirectory(test)
 endif()
+
+if(WITH_STL)
+  message("Building with standard library types...")
+else()
+  message("Building with nostd types...")
+endif()

api/include/opentelemetry/common/attribute_value.h

@@ -10,20 +10,30 @@
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace common
 {
-using AttributeValue = nostd::variant<bool,
-                                      int,
-                                      int64_t,
-                                      unsigned int,
-                                      uint64_t,
-                                      double,
-                                      nostd::string_view,
-                                      nostd::span<const bool>,
-                                      nostd::span<const int>,
-                                      nostd::span<const int64_t>,
-                                      nostd::span<const unsigned int>,
-                                      nostd::span<const uint64_t>,
-                                      nostd::span<const double>,
-                                      nostd::span<const nostd::string_view>>;
+using AttributeValue =
+    nostd::variant<bool,
+                   int32_t,
+                   int64_t,
+                   uint32_t,
+                   uint64_t,
+                   double,
+                   nostd::string_view,
+#ifdef HAVE_CSTRING_TYPE
+                   // TODO: add C-string as possible value on API surface
+                   const char *,
+#endif
+#ifdef HAVE_SPAN_BYTE
+                   // TODO: 8-bit byte arrays / binary blobs are not part of OT spec yet!
+                   // Ref: https://github.com/open-telemetry/opentelemetry-specification/issues/780
+                   nostd::span<const uint8_t>,
+#endif
+                   nostd::span<const bool>,
+                   nostd::span<const int32_t>,
+                   nostd::span<const int64_t>,
+                   nostd::span<const uint32_t>,
+                   nostd::span<const uint64_t>,
+                   nostd::span<const double>,
+                   nostd::span<const nostd::string_view>>;
 
 enum AttributeType
 {
@@ -34,8 +44,12 @@ enum AttributeType
   TYPE_UINT64,
   TYPE_DOUBLE,
   TYPE_STRING,
+#ifdef HAVE_CSTRING_TYPE
   TYPE_CSTRING,
-  // TYPE_SPAN_BYTE, // TODO: not part of OT spec yet
+#endif
+#ifdef HAVE_SPAN_BYTE
+  TYPE_SPAN_BYTE,
+#endif
   TYPE_SPAN_BOOL,
   TYPE_SPAN_INT,
   TYPE_SPAN_INT64,

api/include/opentelemetry/common/key_value_iterable.h

@@ -30,5 +30,23 @@ class KeyValueIterable
    */
   virtual size_t size() const noexcept = 0;
 };
+
+//
+// NULL object pattern empty iterable.
+//
+class NullKeyValueIterable : public KeyValueIterable
+{
+public:
+  NullKeyValueIterable(){};
+
+  virtual bool ForEachKeyValue(
+      nostd::function_ref<bool(nostd::string_view, common::AttributeValue)>) const noexcept
+  {
+    return true;
+  };
+
+  virtual size_t size() const noexcept { return 0; }
+};
+
 }  // namespace common
 OPENTELEMETRY_END_NAMESPACE

api/include/opentelemetry/logs/logger.h

@@ -28,6 +28,7 @@
 #include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/nostd/span.h"
 #include "opentelemetry/nostd/string_view.h"
+#include "opentelemetry/nostd/type_traits.h"
 #include "opentelemetry/trace/span_id.h"
 #include "opentelemetry/trace/trace_flags.h"
 #include "opentelemetry/trace/trace_id.h"

api/include/opentelemetry/nostd/function_ref.h

@@ -1,3 +1,17 @@
+// 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.
+
 #pragma once
 
 #include <memory>