Added Http Trace Context (open-telemetry#143)

api/include/opentelemetry/plugin/tracer.h

@@ -48,7 +48,7 @@ class Span final : public trace::Span
 
   bool IsRecording() const noexcept override { return span_->IsRecording(); }
 
-  trace::Tracer &tracer() const noexcept override { return *tracer_; }
+  trace::SpanContext GetContext() const noexcept override { return span_->GetContext(); }
 
   void SetToken(nostd::unique_ptr<context::Token> &&token) noexcept override {}
 

api/include/opentelemetry/trace/default_span.h

@@ -0,0 +1,59 @@
+#pragma once
+#include "opentelemetry/common/attribute_value.h"
+#include "opentelemetry/trace/canonical_code.h"
+#include "opentelemetry/trace/span.h"
+#include "opentelemetry/trace/span_context.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace trace
+{
+class DefaultSpan : public Span
+{
+public:
+  // Returns an invalid span.
+  static DefaultSpan GetInvalid() { return DefaultSpan(SpanContext::GetInvalid()); }
+
+  trace::SpanContext GetContext() const noexcept { return span_context_; }
+
+  bool IsRecording() const noexcept { return false; }
+
+  void SetAttribute(nostd::string_view key, const common::AttributeValue &value) noexcept {}
+
+  void AddEvent(nostd::string_view name) noexcept {}
+
+  void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept {}
+
+  void AddEvent(nostd::string_view name,
+                core::SystemTimestamp timestamp,
+                const KeyValueIterable &attributes) noexcept
+  {}
+
+  void AddEvent(nostd::string_view name, const KeyValueIterable &attributes) noexcept
+  {
+    this->AddEvent(name, std::chrono::system_clock::now(), attributes);
+  }
+
+  void SetStatus(CanonicalCode status, nostd::string_view description) noexcept {}
+
+  void UpdateName(nostd::string_view name) noexcept {}
+
+  void End(const EndSpanOptions &options = {}) noexcept {}
+
+  nostd::string_view ToString() { return "DefaultSpan"; }
+
+  void SetToken(nostd::unique_ptr<context::Token> &&default_token) noexcept {}
+
+  DefaultSpan() = default;
+
+  DefaultSpan(SpanContext span_context) : span_context_(span_context) {}
+
+  // movable and copiable
+  DefaultSpan(DefaultSpan &&spn) : span_context_(spn.GetContext()) {}
+  DefaultSpan(const DefaultSpan &spn) : span_context_(spn.GetContext()) {}
+
+private:
+  SpanContext span_context_;
+};
+
+}  // namespace trace
+OPENTELEMETRY_END_NAMESPACE

api/include/opentelemetry/trace/default_tracer.h

@@ -0,0 +1,35 @@
+#pragma once
+#include "opentelemetry/nostd/unique_ptr.h"
+#include "opentelemetry/trace/default_span.h"
+#include "opentelemetry/trace/span.h"
+#include "opentelemetry/trace/tracer.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace trace
+{
+class DefaultTracer : public Tracer
+{
+public:
+  ~DefaultTracer() = default;
+
+  /**
+   * Starts a span.
+   *
+   * Optionally sets attributes at Span creation from the given key/value pairs.
+   *
+   * Attributes will be processed in order, previous attributes with the same
+   * key will be overwritten.
+   */
+  nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
+                                    const KeyValueIterable &attributes,
+                                    const StartSpanOptions &options = {}) override noexcept
+  {
+    return nostd::unique_ptr<Span>(new DefaultSpan::GetInvalid());
+  }
+
+  void ForceFlushWithMicroseconds(uint64_t timeout) override noexcept {}
+
+  void CloseWithMicroseconds(uint64_t timeout) override noexcept {}
+};
+}  // namespace trace
+OPENTELEMETRY_END_NAMESPACE

api/include/opentelemetry/trace/noop.h

@@ -8,6 +8,7 @@
 #include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/nostd/unique_ptr.h"
 #include "opentelemetry/trace/span.h"
+#include "opentelemetry/trace/span_context.h"
 #include "opentelemetry/trace/tracer.h"
 #include "opentelemetry/trace/tracer_provider.h"
 #include "opentelemetry/version.h"
@@ -47,12 +48,13 @@ class NoopSpan final : public Span
 
   bool IsRecording() const noexcept override { return false; }
 
-  Tracer &tracer() const noexcept override { return *tracer_; }
+  SpanContext GetContext() const noexcept override { return span_context_; }
 
   void SetToken(nostd::unique_ptr<context::Token> && /* token */) noexcept override {}
 
 private:
   std::shared_ptr<Tracer> tracer_;
+  SpanContext span_context_;
 };
 
 /**

api/include/opentelemetry/trace/propagation/http_text_format.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include <cstdint>
+#include "opentelemetry/context/context.h"
+#include "opentelemetry/nostd/string_view.h"
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace trace
+{
+namespace propagation
+{
+
+// The HTTPTextFormat class provides an interface that enables extracting and injecting
+// context into headers of HTTP requests. HTTP frameworks and clients
+// can integrate with HTTPTextFormat by providing the object containing the
+// headers, and a getter and setter function for the extraction and
+// injection of values, respectively.
+template <typename T>
+class HTTPTextFormat
+{
+public:
+  // Rules that manages how context will be extracted from carrier.
+  using Getter = nostd::string_view (*)(const T &carrier, nostd::string_view trace_type);
+
+  // Rules that manages how context will be injected to carrier.
+  using Setter = void (*)(T &carrier,
+                          nostd::string_view trace_type,
+                          nostd::string_view trace_description);
+
+  // Returns the context that is stored in the HTTP header carrier with the getter as extractor.
+  virtual context::Context Extract(Getter get_from_carrier,
+                                   const T &carrier,
+                                   context::Context &context) noexcept = 0;
+
+  // Sets the context for a HTTP header carrier with self defined rules.
+  virtual void Inject(Setter set_from_carrier,
+                      T &carrier,
+                      const context::Context &context) noexcept = 0;
+};
+}  // namespace propagation
+}  // namespace trace
+OPENTELEMETRY_END_NAMESPACE