Context api alternative implementation

api/include/opentelemetry/context/context.h

@@ -0,0 +1,166 @@
+#pragma once
+
+#include "opentelemetry/context/context_value.h"
+#include "opentelemetry/nostd/shared_ptr.h"
+#include "opentelemetry/nostd/string_view.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace context
+{
+
+// The context class provides a context identifier. Is built as a linked list
+// of DataList nodes and each context holds a shared_ptr to a place within
+// the list that determines which keys and values it has access to. All that
+// come before and none that come after.
+class Context
+{
+
+public:
+  // Creates a context object from a map of keys and identifiers, this will
+  // hold a shared_ptr to the head of the DataList linked list
+  template <class T>
+  Context(const T &keys_and_values)
+  {
+    head_ = nostd::shared_ptr<DataList>{new DataList(keys_and_values)};
+  }
+
+  // Creates a context object from a key and value, this will
+  // hold a shared_ptr to the head of the DataList linked list
+  Context(nostd::string_view key, ContextValue value)
+  {
+    head_ = nostd::shared_ptr<DataList>{new DataList(key, value)};
+  }
+
+  // Accepts a new iterable and then returns a new context that
+  // contains the new key and value data. It attaches the
+  // exisiting list to the end of the new list.
+  template <class T>
+  Context SetValues(T &values) noexcept
+  {
+    Context context                   = Context(values);
+    nostd::shared_ptr<DataList> &last = context.head_;
+    while (last->next_ != nullptr)
+    {
+      last = last->next_;
+    }
+    last->next_ = head_;
+    return context;
+  }
+
+  // Accepts a new iterable and then returns a new context that
+  // contains the new key and value data. It attaches the
+  // exisiting list to the end of the new list.
+  Context SetValue(nostd::string_view key, ContextValue value) noexcept
+  {
+    Context context      = Context(key, value);
+    context.head_->next_ = head_;
+    return context;
+  }
+
+  // Returns the value associated with the passed in key.
+  context::ContextValue GetValue(const nostd::string_view key) noexcept
+  {
+    for (DataList *data = head_.get(); data != nullptr; data = data->next_.get())
+    {
+      if (key.size() == data->key_length_)
+      {
+        if (memcmp(key.data(), data->key_, data->key_length_) == 0)
+        {
+          return data->value_;
+        }
+      }
+    }
+    return (int64_t)0;
+  }
+
+  // Checks for key and returns true if found
+  bool HasKey(const nostd::string_view key) noexcept
+  {
+    for (DataList *data = head_.get(); data != nullptr; data = data->next_.get())
+    {
+      if (key.size() == data->key_length_)
+      {
+        if (memcmp(key.data(), data->key_, data->key_length_) == 0)
+        {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+private:
+  Context() = default;
+
+  // A linked list to contain the keys and values of this context node
+  class DataList
+  {
+  public:
+    nostd::shared_ptr<DataList> next_;
+
+    char *key_;
+
+    size_t key_length_;
+
+    ContextValue value_;
+
+    DataList() { next_ = nullptr; }
+
+    // Builds a data list off of a key and value iterable and returns the head
+    template <class T>
+    DataList(const T &keys_and_vals) : key_{nullptr}
+    {
+      bool first = true;
+      auto *node = this;
+      for (auto &iter : keys_and_vals)
+      {
+        if (first)
+        {
+          *node = std::move(DataList(iter.first, iter.second));
+          first = false;
+        }
+        else
+        {
+          node->next_ = nostd::shared_ptr<DataList>(new DataList(iter.first, iter.second));
+          node        = node->next_.get();
+        }
+      }
+    }
+
+    // Builds a data list with just a key and value, so it will just be the head
+    // and returns that head.
+    DataList(nostd::string_view key, ContextValue value)
+    {
+      key_        = new char[key.size()];
+      key_length_ = key.size();
+      memcpy(key_, key.data(), key.size() * sizeof(char));
+      value_ = value;
+      next_  = nostd::shared_ptr<DataList>{nullptr};
+    }
+
+    DataList &operator=(DataList &&other)
+    {
+      key_length_ = other.key_length_;
+      value_      = std::move(other.value_);
+      next_       = std::move(other.next_);
+
+      key_       = other.key_;
+      other.key_ = nullptr;
+
+      return *this;
+    }
+
+    ~DataList()
+    {
+      if (key_ != nullptr)
+      {
+        delete[] key_;
+      }
+    }
+  };
+
+  // Head of the list which holds the keys and values of this context
+  nostd::shared_ptr<DataList> head_;
+};
+}  // namespace context
+OPENTELEMETRY_END_NAMESPACE

api/include/opentelemetry/context/context_value.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <cstdint>
+
+#include "opentelemetry/nostd/shared_ptr.h"
+#include "opentelemetry/nostd/span.h"
+#include "opentelemetry/nostd/unique_ptr.h"
+#include "opentelemetry/nostd/variant.h"
+#include "opentelemetry/trace/span_context.h"
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace context
+{
+using ContextValue =
+    nostd::variant<bool, int64_t, uint64_t, double, nostd::shared_ptr<trace::SpanContext>>;
+}  // namespace context
+OPENTELEMETRY_END_NAMESPACE

api/test/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(core)
+add_subdirectory(context)
 add_subdirectory(plugin)
 add_subdirectory(nostd)
 add_subdirectory(trace)

api/test/context/BUILD

@@ -0,0 +1,12 @@
+load("//bazel:otel_cc_benchmark.bzl", "otel_cc_benchmark")
+
+cc_test(
+    name = "context_test",
+    srcs = [
+        "context_test.cc",
+    ],
+    deps = [
+        "//api",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

api/test/context/CMakeLists.txt

@@ -0,0 +1,8 @@
+include(GoogleTest)
+
+foreach(testname context_test)
+  add_executable(${testname} "${testname}.cc")
+  target_link_libraries(${testname} ${GTEST_BOTH_LIBRARIES}
+                        ${CMAKE_THREAD_LIBS_INIT} opentelemetry_api)
+  gtest_add_tests(TARGET ${testname} TEST_PREFIX context. TEST_LIST ${testname})
+endforeach()

api/test/context/context_test.cc

@@ -0,0 +1,120 @@
+#include "opentelemetry/context/context.h"
+
+#include <map>
+
+#include <gtest/gtest.h>
+
+using namespace opentelemetry;
+
+// Tests that the context constructor accepts an std::map.
+TEST(ContextTest, ContextIterableAcceptsMap)
+{
+  std::map<std::string, context::ContextValue> map_test = {{"test_key", (int64_t)123}};
+  context::Context test_context                         = context::Context(map_test);
+}
+
+// Tests that the GetValue method returns the expected value.
+TEST(ContextTest, ContextGetValueReturnsExpectedValue)
+{
+  std::map<std::string, context::ContextValue> map_test = {{"test_key", (int64_t)123},
+                                                           {"foo_key", (int64_t)456}};
+  context::Context test_context                         = context::Context(map_test);
+  EXPECT_EQ(nostd::get<int64_t>(test_context.GetValue("test_key")), 123);
+  EXPECT_EQ(nostd::get<int64_t>(test_context.GetValue("foo_key")), 456);
+}
+
+// Tests that the SetValues method accepts an std::map.
+TEST(ContextTest, ContextSetValuesAcceptsMap)
+{
+  std::map<std::string, context::ContextValue> map_test       = {{"test_key", (int64_t)123}};
+  std::map<std::string, context::ContextValue> map_test_write = {{"foo_key", (int64_t)456}};
+
+  context::Context test_context = context::Context(map_test);
+  context::Context foo_context  = test_context.SetValues(map_test_write);
+
+  EXPECT_EQ(nostd::get<int64_t>(foo_context.GetValue("test_key")), 123);
+  EXPECT_EQ(nostd::get<int64_t>(foo_context.GetValue("foo_key")), 456);
+}
+
+// Tests that the SetValues method accepts a nostd::string_view and
+// context::ContextValue.
+TEST(ContextTest, ContextSetValuesAcceptsStringViewContextValue)
+{
+  nostd::string_view string_view_test      = "string_view";
+  context::ContextValue context_value_test = (int64_t)123;
+
+  context::Context test_context = context::Context(string_view_test, context_value_test);
+  context::Context foo_context  = test_context.SetValue(string_view_test, context_value_test);
+
+  EXPECT_EQ(nostd::get<int64_t>(foo_context.GetValue(string_view_test)), 123);
+}
+
+// Tests that the original context does not change when a value is
+// written to it.
+TEST(ContextTest, ContextImmutability)
+{
+  std::map<std::string, context::ContextValue> map_test = {{"test_key", (int64_t)123}};
+
+  context::Context context_test = context::Context(map_test);
+  context::Context context_foo  = context_test.SetValue("foo_key", (int64_t)456);
+
+  EXPECT_NE(nostd::get<int64_t>(context_test.GetValue("foo_key")), 456);
+}
+
+// Tests that writing the same to a context overwrites the original value.
+TEST(ContextTest, ContextKeyOverwrite)
+{
+  std::map<std::string, context::ContextValue> map_test = {{"test_key", (int64_t)123}};
+
+  context::Context context_test = context::Context(map_test);
+  context::Context context_foo  = context_test.SetValue("test_key", (int64_t)456);
+
+  EXPECT_EQ(nostd::get<int64_t>(context_foo.GetValue("test_key")), 456);
+}
+
+// Tests that the new Context Objects inherits the keys and values
+// of the original context object.
+TEST(ContextTest, ContextInheritance)
+{
+  using M = std::map<std::string, context::ContextValue>;
+
+  M m1 = {{"test_key", (int64_t)123}, {"foo_key", (int64_t)456}};
+  M m2 = {{"other_key", (int64_t)789}};
+
+  context::Context test_context = context::Context(m1);
+  context::Context foo_context  = test_context.SetValues(m2);
+
+  EXPECT_EQ(nostd::get<int64_t>(foo_context.GetValue("test_key")), 123);
+  EXPECT_EQ(nostd::get<int64_t>(foo_context.GetValue("foo_key")), 456);
+}
+
+// Tests that copying a context copies the key value pairs as expected.
+TEST(ContextTest, ContextCopyOperator)
+{
+  std::map<std::string, context::ContextValue> test_map = {
+      {"test_key", (int64_t)123}, {"foo_key", (int64_t)456}, {"other_key", (int64_t)789}};
+
+  context::Context test_context   = context::Context(test_map);
+  context::Context copied_context = test_context;
+
+  EXPECT_EQ(nostd::get<int64_t>(copied_context.GetValue("test_key")), 123);
+  EXPECT_EQ(nostd::get<int64_t>(copied_context.GetValue("foo_key")), 456);
+  EXPECT_EQ(nostd::get<int64_t>(copied_context.GetValue("other_key")), 789);
+}
+
+// Tests that the Context accepts an empty map.
+TEST(ContextTest, ContextEmptyMap)
+{
+  std::map<std::string, context::ContextValue> map_test = {};
+  context::Context test_context                         = context::Context(map_test);
+}
+
+// Tests that if a key exists within a context has key will return true
+// false if not.
+TEST(ContextTest, ContextHasKey)
+{
+  std::map<std::string, context::ContextValue> map_test = {{"test_key", (int64_t)123}};
+  context::Context context_test                         = context::Context(map_test);
+  EXPECT_TRUE(context_test.HasKey("test_key"));
+  EXPECT_FALSE(context_test.HasKey("foo_key"));
+}