From 8dd7be1899fba2563d6b87e67b37618bdb986bfc Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Mon, 28 Sep 2020 18:55:27 +0530
Subject: [PATCH 1/8]  first draft

---
 api/include/opentelemetry/plugin/tracer.h     |  5 +++
 .../opentelemetry/trace/default_span.h        |  7 ++++
 api/include/opentelemetry/trace/link.h        | 22 ++++++++++
 api/include/opentelemetry/trace/noop.h        |  7 +++-
 api/include/opentelemetry/trace/span.h        | 16 ++++++++
 examples/plugin/plugin/tracer.cc              |  7 ++++
 sdk/include/opentelemetry/sdk/trace/link.h    | 40 +++++++++++++++++++
 sdk/src/trace/span.cc                         | 28 ++++++++++++-
 sdk/src/trace/span.h                          |  9 ++++-
 sdk/src/trace/tracer.cc                       |  2 +-
 10 files changed, 139 insertions(+), 4 deletions(-)
 create mode 100644 api/include/opentelemetry/trace/link.h
 create mode 100644 sdk/include/opentelemetry/sdk/trace/link.h

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index aed1d26d28..58365c9605 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -5,6 +5,7 @@
 #include "opentelemetry/plugin/detail/dynamic_library_handle.h"
 #include "opentelemetry/plugin/detail/tracer_handle.h"
 #include "opentelemetry/trace/tracer.h"
+#include "opentelemetry/trace/link.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -37,6 +38,10 @@ class Span final : public trace::Span
     span_->AddEvent(name, timestamp, attributes);
   }
 
+  virtual void AddLink(const trace::Link &link) noexcept override {}
+  virtual void AddLink(trace::SpanContext spanContext, 
+                      const trace::KeyValueIterable& attributes) noexcept override {}
+
   void SetStatus(trace::CanonicalCode code, nostd::string_view description) noexcept override
   {
     span_->SetStatus(code, description);
diff --git a/api/include/opentelemetry/trace/default_span.h b/api/include/opentelemetry/trace/default_span.h
index 9dbe682bc7..ba063a4a59 100644
--- a/api/include/opentelemetry/trace/default_span.h
+++ b/api/include/opentelemetry/trace/default_span.h
@@ -33,6 +33,13 @@ class DefaultSpan : public Span
     this->AddEvent(name, std::chrono::system_clock::now(), attributes);
   }
 
+  virtual void AddLink(const trace::Link &link) noexcept override
+  {}
+
+  virtual void AddLink(trace::SpanContext spanContext, 
+                      const trace::KeyValueIterable& attributes) noexcept override
+  {}
+
   void SetStatus(CanonicalCode status, nostd::string_view description) noexcept {}
 
   void UpdateName(nostd::string_view name) noexcept {}
diff --git a/api/include/opentelemetry/trace/link.h b/api/include/opentelemetry/trace/link.h
new file mode 100644
index 0000000000..b1800cfcf6
--- /dev/null
+++ b/api/include/opentelemetry/trace/link.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "opentelemetry/version.h"
+#include "opentelemetry/trace/key_value_iterable.h"
+#include "opentelemetry/trace/span_context.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE 
+namespace trace
+{
+class Link 
+{
+public:
+
+    //returns the Span Context associated with this Link
+    virtual const SpanContext& GetContext() const = 0 ;
+
+    // returns the attributes associated with link
+    virtual const KeyValueIterable& GetAttributes() const = 0;
+
+};
+}  // namespace trace
+OPENTELEMETRY_END_NAMESPACE
\ No newline at end of file
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index b88b1b3093..2b512896f3 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -15,7 +15,7 @@
 
 #include <memory>
 
-OPENTELEMETRY_BEGIN_NAMESPACE
+OPENTELEMETRY_BEGIN_NAMESPACE 
 namespace trace
 {
 /**
@@ -40,6 +40,11 @@ class NoopSpan final : public Span
                 const trace::KeyValueIterable & /*attributes*/) noexcept override
   {}
 
+  virtual void AddLink(const Link &link) noexcept override {}
+
+  virtual void AddLink(trace_api::SpanContext spanContext, 
+                      const trace_api::KeyValueIterable& attributes) noexcept override {}
+                      
   void SetStatus(CanonicalCode /*code*/, nostd::string_view /*description*/) noexcept override {}
 
   void UpdateName(nostd::string_view /*name*/) noexcept override {}
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 922f38fb92..964033e8a8 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -10,6 +10,7 @@
 #include "opentelemetry/trace/canonical_code.h"
 #include "opentelemetry/trace/key_value_iterable_view.h"
 #include "opentelemetry/trace/span_context.h"
+#include "opentelemetry/trace/link.h"
 #include "opentelemetry/version.h"
 
 constexpr char SpanKey[] = "span_key";
@@ -135,6 +136,21 @@ class Span
                        attributes.begin(), attributes.end()});
   }
 
+  /** Adds a Link to newly created Span
+   *  @param spanContext the context of the linked span
+   *  @param attributes Link attributes
+   */
+ 
+  virtual void AddLink(const trace::Link &link) noexcept = 0;
+  virtual void AddLink(trace::SpanContext spanContext, 
+                      const trace::KeyValueIterable& attributes) noexcept = 0; 
+
+  template <class T, nostd::enable_if_t<detail::is_key_value_iterable<T>::value> * = nullptr>
+  void AddLink(trace_api::SpanContext spanContext) noexcept
+  {
+    this->AddLink(spanContext, KeyValueIterableView<T>{});
+  }                   
+
   // Sets the status of the span. The default status is OK. Only the value of
   // the last call will be
   // recorded, and implementations are free to ignore previous calls.
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index e8f324c9e7..f6e8a34ab4 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -42,6 +42,13 @@ class Span final : public trace::Span
                 const trace::KeyValueIterable & /*attributes*/) noexcept override
   {}
 
+  void AddLink(const trace::Link &link) noexcept override
+  {}
+
+  void AddLink(trace::SpanContext spanContext, 
+                      const trace::KeyValueIterable& attributes) noexcept override
+  {}
+
   void SetStatus(trace::CanonicalCode /*code*/,
                  nostd::string_view /*description*/) noexcept override
   {}
diff --git a/sdk/include/opentelemetry/sdk/trace/link.h b/sdk/include/opentelemetry/sdk/trace/link.h
new file mode 100644
index 0000000000..8cd61c627e
--- /dev/null
+++ b/sdk/include/opentelemetry/sdk/trace/link.h
@@ -0,0 +1,40 @@
+#pragma once
+
+#include "opentelemetry/trace/link.h"
+#include "opentelemetry/sdk/trace/attribute_utils.h"
+#include "opentelemetry/version.h"
+
+#include <memory>
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace trace
+{
+class Link final : public trace_api::Link
+{
+public:
+    Link( opentelemetry::trace::SpanContext span_context, 
+          const opentelemetry::trace::KeyValueIterableView<std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>> &attributes) noexcept
+        : span_context_(span_context), attribute_map_{attributes}
+    {
+    }
+ 
+    const trace_api::SpanContext& GetContext() const noexcept override
+    {
+      return span_context_;
+    }
+
+    const trace_api::KeyValueIterable & GetAttributes() const noexcept override
+    {
+      return attribute_map_;
+      
+    }
+
+private:
+  trace_api::SpanContext span_context_;
+  const trace_api::KeyValueIterableView<std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>> attribute_map_;
+};
+}  // namespace trace
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 0f661d8ef6..d43f3e4264 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -62,13 +62,15 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
            nostd::string_view name,
            const trace_api::KeyValueIterable &attributes,
            const trace_api::StartSpanOptions &options,
-           const trace_api::SpanContext &parent_span_context) noexcept
+           const trace_api::SpanContext &parent_span_context,
+           const nostd::span<std::shared_ptr<trace_api::Link>> &links) noexcept
     : tracer_{std::move(tracer)},
       processor_{processor},
       recordable_{processor_->MakeRecordable()},
       start_steady_time{options.start_steady_time},
       has_ended_{false}
 {
+  (void)options;
   if (recordable_ == nullptr)
   {
     return;
@@ -98,6 +100,11 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
     return true;
   });
 
+  for (auto &link: links)
+  {
+    recordable_->AddLink(link->GetContext(), link->GetAttributes());
+  }
+
   recordable_->SetStartTime(NowOr(options.start_system_time));
   start_steady_time = NowOr(options.start_steady_time);
   processor_->OnStart(*recordable_);
@@ -136,6 +143,25 @@ void Span::AddEvent(nostd::string_view name,
   (void)attributes;
 }
 
+void Span::AddLink(const trace_api::Link& link) noexcept
+{
+  if (recordable_ == nullptr)
+  {
+    return;
+  }
+  recordable_->AddLink(link.GetContext(), link.GetAttributes());
+}
+
+void Span::AddLink(trace_api::SpanContext spanContext, 
+              const trace_api::KeyValueIterable& attributes) noexcept
+{
+    if (recordable_ == nullptr )
+    {
+      return;
+    }
+    recordable_->AddLink(spanContext, attributes);
+}
+
 void Span::SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept
 {
   std::lock_guard<std::mutex> lock_guard{mu_};
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index 56baf8838f..33397643ae 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -3,6 +3,7 @@
 #include <mutex>
 
 #include "opentelemetry/sdk/trace/tracer.h"
+#include "opentelemetry/sdk/trace/link.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -20,7 +21,8 @@ class Span final : public trace_api::Span
                 nostd::string_view name,
                 const trace_api::KeyValueIterable &attributes,
                 const trace_api::StartSpanOptions &options,
-                const trace_api::SpanContext &parent_span_context) noexcept;
+                const trace_api::SpanContext &parent_span_context,
+                const nostd::span<std::shared_ptr<trace_api::Link>> &links) noexcept;
 
   ~Span() override;
 
@@ -35,6 +37,11 @@ class Span final : public trace_api::Span
                 core::SystemTimestamp timestamp,
                 const trace_api::KeyValueIterable &attributes) noexcept override;
 
+  virtual void AddLink(const trace_api::Link &link) noexcept override;
+
+  virtual void AddLink(trace_api::SpanContext spanContext, 
+                      const trace_api::KeyValueIterable& attributes) noexcept override;
+
   void SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept override;
 
   void UpdateName(nostd::string_view name) noexcept override;
diff --git a/sdk/src/trace/tracer.cc b/sdk/src/trace/tracer.cc
index 60b00f191c..b8d507ffd3 100644
--- a/sdk/src/trace/tracer.cc
+++ b/sdk/src/trace/tracer.cc
@@ -63,7 +63,7 @@ nostd::shared_ptr<trace_api::Span> Tracer::StartSpan(
   {
     auto span = nostd::shared_ptr<trace_api::Span>{
         new (std::nothrow) Span{this->shared_from_this(), processor_.load(), name, attributes,
-                                options, GetCurrentSpanContext()}};
+                                options, GetCurrentSpanContext(), {}}};
 
     // if the attributes is not nullptr, add attributes to the span.
     if (sampling_result.attributes)

From 375322f0881cb9e452acf60b2a5db90a5be72dc6 Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Mon, 28 Sep 2020 19:10:09 +0530
Subject: [PATCH 2/8] fix format

---
 api/include/opentelemetry/plugin/tracer.h     |  7 ++--
 .../opentelemetry/trace/default_span.h        |  7 ++--
 api/include/opentelemetry/trace/link.h        | 16 ++++-----
 api/include/opentelemetry/trace/noop.h        |  9 ++---
 api/include/opentelemetry/trace/span.h        | 12 +++----
 examples/plugin/plugin/tracer.cc              |  7 ++--
 sdk/include/opentelemetry/sdk/trace/link.h    | 33 +++++++++----------
 sdk/src/trace/span.cc                         | 18 +++++-----
 sdk/src/trace/span.h                          |  6 ++--
 sdk/src/trace/tracer.cc                       | 10 ++++--
 10 files changed, 63 insertions(+), 62 deletions(-)

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index 58365c9605..f2e3a6e430 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -4,8 +4,8 @@
 
 #include "opentelemetry/plugin/detail/dynamic_library_handle.h"
 #include "opentelemetry/plugin/detail/tracer_handle.h"
-#include "opentelemetry/trace/tracer.h"
 #include "opentelemetry/trace/link.h"
+#include "opentelemetry/trace/tracer.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -39,8 +39,9 @@ class Span final : public trace::Span
   }
 
   virtual void AddLink(const trace::Link &link) noexcept override {}
-  virtual void AddLink(trace::SpanContext spanContext, 
-                      const trace::KeyValueIterable& attributes) noexcept override {}
+  virtual void AddLink(trace::SpanContext spanContext,
+                       const trace::KeyValueIterable &attributes) noexcept override
+  {}
 
   void SetStatus(trace::CanonicalCode code, nostd::string_view description) noexcept override
   {
diff --git a/api/include/opentelemetry/trace/default_span.h b/api/include/opentelemetry/trace/default_span.h
index ba063a4a59..ebaaa5c0af 100644
--- a/api/include/opentelemetry/trace/default_span.h
+++ b/api/include/opentelemetry/trace/default_span.h
@@ -33,11 +33,10 @@ class DefaultSpan : public Span
     this->AddEvent(name, std::chrono::system_clock::now(), attributes);
   }
 
-  virtual void AddLink(const trace::Link &link) noexcept override
-  {}
+  virtual void AddLink(const trace::Link &link) noexcept override {}
 
-  virtual void AddLink(trace::SpanContext spanContext, 
-                      const trace::KeyValueIterable& attributes) noexcept override
+  virtual void AddLink(trace::SpanContext spanContext,
+                       const trace::KeyValueIterable &attributes) noexcept override
   {}
 
   void SetStatus(CanonicalCode status, nostd::string_view description) noexcept {}
diff --git a/api/include/opentelemetry/trace/link.h b/api/include/opentelemetry/trace/link.h
index b1800cfcf6..2ece0200b9 100644
--- a/api/include/opentelemetry/trace/link.h
+++ b/api/include/opentelemetry/trace/link.h
@@ -1,22 +1,20 @@
 #pragma once
 
-#include "opentelemetry/version.h"
 #include "opentelemetry/trace/key_value_iterable.h"
 #include "opentelemetry/trace/span_context.h"
+#include "opentelemetry/version.h"
 
-OPENTELEMETRY_BEGIN_NAMESPACE 
+OPENTELEMETRY_BEGIN_NAMESPACE
 namespace trace
 {
-class Link 
+class Link
 {
 public:
+  // returns the Span Context associated with this Link
+  virtual const SpanContext &GetContext() const = 0;
 
-    //returns the Span Context associated with this Link
-    virtual const SpanContext& GetContext() const = 0 ;
-
-    // returns the attributes associated with link
-    virtual const KeyValueIterable& GetAttributes() const = 0;
-
+  // returns the attributes associated with link
+  virtual const KeyValueIterable &GetAttributes() const = 0;
 };
 }  // namespace trace
 OPENTELEMETRY_END_NAMESPACE
\ No newline at end of file
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 2b512896f3..426747c48a 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -15,7 +15,7 @@
 
 #include <memory>
 
-OPENTELEMETRY_BEGIN_NAMESPACE 
+OPENTELEMETRY_BEGIN_NAMESPACE
 namespace trace
 {
 /**
@@ -42,9 +42,10 @@ class NoopSpan final : public Span
 
   virtual void AddLink(const Link &link) noexcept override {}
 
-  virtual void AddLink(trace_api::SpanContext spanContext, 
-                      const trace_api::KeyValueIterable& attributes) noexcept override {}
-                      
+  virtual void AddLink(trace_api::SpanContext spanContext,
+                       const trace_api::KeyValueIterable &attributes) noexcept override
+  {}
+
   void SetStatus(CanonicalCode /*code*/, nostd::string_view /*description*/) noexcept override {}
 
   void UpdateName(nostd::string_view /*name*/) noexcept override {}
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 964033e8a8..c7728f2679 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -9,8 +9,8 @@
 #include "opentelemetry/nostd/unique_ptr.h"
 #include "opentelemetry/trace/canonical_code.h"
 #include "opentelemetry/trace/key_value_iterable_view.h"
-#include "opentelemetry/trace/span_context.h"
 #include "opentelemetry/trace/link.h"
+#include "opentelemetry/trace/span_context.h"
 #include "opentelemetry/version.h"
 
 constexpr char SpanKey[] = "span_key";
@@ -140,16 +140,16 @@ class Span
    *  @param spanContext the context of the linked span
    *  @param attributes Link attributes
    */
- 
-  virtual void AddLink(const trace::Link &link) noexcept = 0;
-  virtual void AddLink(trace::SpanContext spanContext, 
-                      const trace::KeyValueIterable& attributes) noexcept = 0; 
+
+  virtual void AddLink(const trace::Link &link) noexcept                   = 0;
+  virtual void AddLink(trace::SpanContext spanContext,
+                       const trace::KeyValueIterable &attributes) noexcept = 0;
 
   template <class T, nostd::enable_if_t<detail::is_key_value_iterable<T>::value> * = nullptr>
   void AddLink(trace_api::SpanContext spanContext) noexcept
   {
     this->AddLink(spanContext, KeyValueIterableView<T>{});
-  }                   
+  }
 
   // Sets the status of the span. The default status is OK. Only the value of
   // the last call will be
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index f6e8a34ab4..034f1b5655 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -42,11 +42,10 @@ class Span final : public trace::Span
                 const trace::KeyValueIterable & /*attributes*/) noexcept override
   {}
 
-  void AddLink(const trace::Link &link) noexcept override
-  {}
+  void AddLink(const trace::Link &link) noexcept override {}
 
-  void AddLink(trace::SpanContext spanContext, 
-                      const trace::KeyValueIterable& attributes) noexcept override
+  void AddLink(trace::SpanContext spanContext,
+               const trace::KeyValueIterable &attributes) noexcept override
   {}
 
   void SetStatus(trace::CanonicalCode /*code*/,
diff --git a/sdk/include/opentelemetry/sdk/trace/link.h b/sdk/include/opentelemetry/sdk/trace/link.h
index 8cd61c627e..7d8407cee3 100644
--- a/sdk/include/opentelemetry/sdk/trace/link.h
+++ b/sdk/include/opentelemetry/sdk/trace/link.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "opentelemetry/trace/link.h"
 #include "opentelemetry/sdk/trace/attribute_utils.h"
+#include "opentelemetry/trace/link.h"
 #include "opentelemetry/version.h"
 
 #include <memory>
@@ -14,26 +14,25 @@ namespace trace
 class Link final : public trace_api::Link
 {
 public:
-    Link( opentelemetry::trace::SpanContext span_context, 
-          const opentelemetry::trace::KeyValueIterableView<std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>> &attributes) noexcept
-        : span_context_(span_context), attribute_map_{attributes}
-    {
-    }
- 
-    const trace_api::SpanContext& GetContext() const noexcept override
-    {
-      return span_context_;
-    }
+  Link(opentelemetry::trace::SpanContext span_context,
+       const opentelemetry::trace::KeyValueIterableView<
+           std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>>
+           &attributes) noexcept
+      : span_context_(span_context), attribute_map_{attributes}
+  {}
+
+  const trace_api::SpanContext &GetContext() const noexcept override { return span_context_; }
 
-    const trace_api::KeyValueIterable & GetAttributes() const noexcept override
-    {
-      return attribute_map_;
-      
-    }
+  const trace_api::KeyValueIterable &GetAttributes() const noexcept override
+  {
+    return attribute_map_;
+  }
 
 private:
   trace_api::SpanContext span_context_;
-  const trace_api::KeyValueIterableView<std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>> attribute_map_;
+  const trace_api::KeyValueIterableView<
+      std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>>
+      attribute_map_;
 };
 }  // namespace trace
 }  // namespace sdk
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index d43f3e4264..14e6b6c56f 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -100,7 +100,7 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
     return true;
   });
 
-  for (auto &link: links)
+  for (auto &link : links)
   {
     recordable_->AddLink(link->GetContext(), link->GetAttributes());
   }
@@ -143,7 +143,7 @@ void Span::AddEvent(nostd::string_view name,
   (void)attributes;
 }
 
-void Span::AddLink(const trace_api::Link& link) noexcept
+void Span::AddLink(const trace_api::Link &link) noexcept
 {
   if (recordable_ == nullptr)
   {
@@ -152,14 +152,14 @@ void Span::AddLink(const trace_api::Link& link) noexcept
   recordable_->AddLink(link.GetContext(), link.GetAttributes());
 }
 
-void Span::AddLink(trace_api::SpanContext spanContext, 
-              const trace_api::KeyValueIterable& attributes) noexcept
+void Span::AddLink(trace_api::SpanContext spanContext,
+                   const trace_api::KeyValueIterable &attributes) noexcept
 {
-    if (recordable_ == nullptr )
-    {
-      return;
-    }
-    recordable_->AddLink(spanContext, attributes);
+  if (recordable_ == nullptr)
+  {
+    return;
+  }
+  recordable_->AddLink(spanContext, attributes);
 }
 
 void Span::SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index 33397643ae..eb64797532 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -2,8 +2,8 @@
 
 #include <mutex>
 
-#include "opentelemetry/sdk/trace/tracer.h"
 #include "opentelemetry/sdk/trace/link.h"
+#include "opentelemetry/sdk/trace/tracer.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -39,8 +39,8 @@ class Span final : public trace_api::Span
 
   virtual void AddLink(const trace_api::Link &link) noexcept override;
 
-  virtual void AddLink(trace_api::SpanContext spanContext, 
-                      const trace_api::KeyValueIterable& attributes) noexcept override;
+  virtual void AddLink(trace_api::SpanContext spanContext,
+                       const trace_api::KeyValueIterable &attributes) noexcept override;
 
   void SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept override;
 
diff --git a/sdk/src/trace/tracer.cc b/sdk/src/trace/tracer.cc
index b8d507ffd3..eaeada03f9 100644
--- a/sdk/src/trace/tracer.cc
+++ b/sdk/src/trace/tracer.cc
@@ -61,9 +61,13 @@ nostd::shared_ptr<trace_api::Span> Tracer::StartSpan(
   }
   else
   {
-    auto span = nostd::shared_ptr<trace_api::Span>{
-        new (std::nothrow) Span{this->shared_from_this(), processor_.load(), name, attributes,
-                                options, GetCurrentSpanContext(), {}}};
+    auto span = nostd::shared_ptr<trace_api::Span>{new (std::nothrow) Span{this->shared_from_this(),
+                                                                           processor_.load(),
+                                                                           name,
+                                                                           attributes,
+                                                                           options,
+                                                                           GetCurrentSpanContext(),
+                                                                           {}}};
 
     // if the attributes is not nullptr, add attributes to the span.
     if (sampling_result.attributes)

From 0513e54ae8c28aac3fa0c7ff7879b3b620b98cfe Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Mon, 28 Sep 2020 19:17:21 +0530
Subject: [PATCH 3/8] fix trace_api

---
 sdk/include/opentelemetry/sdk/trace/link.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sdk/include/opentelemetry/sdk/trace/link.h b/sdk/include/opentelemetry/sdk/trace/link.h
index 7d8407cee3..8ec4d88710 100644
--- a/sdk/include/opentelemetry/sdk/trace/link.h
+++ b/sdk/include/opentelemetry/sdk/trace/link.h
@@ -11,6 +11,8 @@ namespace sdk
 {
 namespace trace
 {
+namespace trace_api = opentelemetry::trace;
+
 class Link final : public trace_api::Link
 {
 public:

From 65970990a17412b66197a78d43bfcc2b57d7f776 Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Tue, 29 Sep 2020 00:41:14 +0530
Subject: [PATCH 4/8]  fix coverage

---
 api/include/opentelemetry/plugin/tracer.h      | 12 ++++++++----
 api/include/opentelemetry/trace/default_span.h |  8 +++++---
 api/include/opentelemetry/trace/noop.h         |  8 +++++---
 api/include/opentelemetry/trace/span.h         |  9 +++------
 api/test/trace/noop_test.cc                    |  8 ++++++++
 examples/plugin/plugin/tracer.cc               |  2 ++
 sdk/include/opentelemetry/sdk/trace/link.h     |  6 ++++++
 sdk/src/trace/span.cc                          |  9 +++++++++
 sdk/src/trace/span.h                           |  8 +++++---
 9 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index f2e3a6e430..e9c333dccf 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -38,10 +38,14 @@ class Span final : public trace::Span
     span_->AddEvent(name, timestamp, attributes);
   }
 
-  virtual void AddLink(const trace::Link &link) noexcept override {}
-  virtual void AddLink(trace::SpanContext spanContext,
-                       const trace::KeyValueIterable &attributes) noexcept override
-  {}
+  void AddLink(const trace::Link &link) noexcept override { span_->AddLink(link); }
+  void AddLink(trace::SpanContext spanContext,
+               const trace::KeyValueIterable &attributes) noexcept override
+  {
+    span_->AddLink(spanContext, attributes);
+  }
+
+  void AddLink(trace::SpanContext spanContext) noexcept override { span_->AddLink(spanContext); }
 
   void SetStatus(trace::CanonicalCode code, nostd::string_view description) noexcept override
   {
diff --git a/api/include/opentelemetry/trace/default_span.h b/api/include/opentelemetry/trace/default_span.h
index ebaaa5c0af..b9e129ef49 100644
--- a/api/include/opentelemetry/trace/default_span.h
+++ b/api/include/opentelemetry/trace/default_span.h
@@ -33,12 +33,14 @@ class DefaultSpan : public Span
     this->AddEvent(name, std::chrono::system_clock::now(), attributes);
   }
 
-  virtual void AddLink(const trace::Link &link) noexcept override {}
+  void AddLink(const trace::Link &link) noexcept override {}
 
-  virtual void AddLink(trace::SpanContext spanContext,
-                       const trace::KeyValueIterable &attributes) noexcept override
+  void AddLink(trace::SpanContext spanContext,
+               const trace::KeyValueIterable &attributes) noexcept override
   {}
 
+  void AddLink(trace::SpanContext spanContext) noexcept override {}
+
   void SetStatus(CanonicalCode status, nostd::string_view description) noexcept {}
 
   void UpdateName(nostd::string_view name) noexcept {}
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 426747c48a..60c3896840 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -40,12 +40,14 @@ class NoopSpan final : public Span
                 const trace::KeyValueIterable & /*attributes*/) noexcept override
   {}
 
-  virtual void AddLink(const Link &link) noexcept override {}
+  void AddLink(const Link &link) noexcept override {}
 
-  virtual void AddLink(trace_api::SpanContext spanContext,
-                       const trace_api::KeyValueIterable &attributes) noexcept override
+  void AddLink(trace_api::SpanContext spanContext,
+               const trace_api::KeyValueIterable &attributes) noexcept override
   {}
 
+  void AddLink(trace_api::SpanContext spanContext) noexcept override {}
+
   void SetStatus(CanonicalCode /*code*/, nostd::string_view /*description*/) noexcept override {}
 
   void UpdateName(nostd::string_view /*name*/) noexcept override {}
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index c7728f2679..50215ebc81 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -141,15 +141,12 @@ class Span
    *  @param attributes Link attributes
    */
 
-  virtual void AddLink(const trace::Link &link) noexcept                   = 0;
+  virtual void AddLink(const trace::Link &link) noexcept = 0;
+
   virtual void AddLink(trace::SpanContext spanContext,
                        const trace::KeyValueIterable &attributes) noexcept = 0;
 
-  template <class T, nostd::enable_if_t<detail::is_key_value_iterable<T>::value> * = nullptr>
-  void AddLink(trace_api::SpanContext spanContext) noexcept
-  {
-    this->AddLink(spanContext, KeyValueIterableView<T>{});
-  }
+  virtual void AddLink(trace::SpanContext spanContext) noexcept = 0;
 
   // Sets the status of the span. The default status is OK. Only the value of
   // the last call will be
diff --git a/api/test/trace/noop_test.cc b/api/test/trace/noop_test.cc
index 4a069430ef..d1f571becf 100644
--- a/api/test/trace/noop_test.cc
+++ b/api/test/trace/noop_test.cc
@@ -1,5 +1,6 @@
 #include "opentelemetry/trace/noop.h"
 #include "opentelemetry/core/timestamp.h"
+#include "opentelemetry/trace/key_value_iterable_view.h"
 
 #include <map>
 #include <memory>
@@ -31,6 +32,13 @@ TEST(NoopTest, UseNoopTracers)
   s1->SetAttribute("abc", 4);
 
   s1->AddEvent("abc");  // add Empty
+  SpanContext sp(false, false);
+  s1->AddLink(sp);
+  using M = std::map<std::string, std::string>;
+  M m1    = {{"abc", "123"}, {"xyz", "456"}};
+  opentelemetry::trace::KeyValueIterableView<M> iterable{m1};
+
+  s1->AddLink(sp, iterable);
 
   EXPECT_EQ(s1->IsRecording(), false);
 
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index 034f1b5655..bad5420e6b 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -48,6 +48,8 @@ class Span final : public trace::Span
                const trace::KeyValueIterable &attributes) noexcept override
   {}
 
+  void AddLink(trace::SpanContext spanContext) noexcept override {}
+
   void SetStatus(trace::CanonicalCode /*code*/,
                  nostd::string_view /*description*/) noexcept override
   {}
diff --git a/sdk/include/opentelemetry/sdk/trace/link.h b/sdk/include/opentelemetry/sdk/trace/link.h
index 8ec4d88710..1488d1501c 100644
--- a/sdk/include/opentelemetry/sdk/trace/link.h
+++ b/sdk/include/opentelemetry/sdk/trace/link.h
@@ -23,6 +23,12 @@ class Link final : public trace_api::Link
       : span_context_(span_context), attribute_map_{attributes}
   {}
 
+  Link(opentelemetry::trace::SpanContext span_context)
+      : span_context_(span_context),
+        attribute_map_(
+            std::unordered_map<nostd::string_view, opentelemetry::common::AttributeValue>())
+  {}
+
   const trace_api::SpanContext &GetContext() const noexcept override { return span_context_; }
 
   const trace_api::KeyValueIterable &GetAttributes() const noexcept override
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 14e6b6c56f..512f88292c 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -162,6 +162,15 @@ void Span::AddLink(trace_api::SpanContext spanContext,
   recordable_->AddLink(spanContext, attributes);
 }
 
+void Span::AddLink(trace_api::SpanContext spanContext) noexcept
+{
+  if (recordable_ == nullptr)
+  {
+    return;
+  }
+  recordable_->AddLink(spanContext);
+}
+
 void Span::SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept
 {
   std::lock_guard<std::mutex> lock_guard{mu_};
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index eb64797532..493778bdd3 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -37,10 +37,12 @@ class Span final : public trace_api::Span
                 core::SystemTimestamp timestamp,
                 const trace_api::KeyValueIterable &attributes) noexcept override;
 
-  virtual void AddLink(const trace_api::Link &link) noexcept override;
+  void AddLink(const trace_api::Link &link) noexcept override;
 
-  virtual void AddLink(trace_api::SpanContext spanContext,
-                       const trace_api::KeyValueIterable &attributes) noexcept override;
+  void AddLink(trace_api::SpanContext spanContext,
+               const trace_api::KeyValueIterable &attributes) noexcept override;
+
+  void AddLink(trace_api::SpanContext spanContext) noexcept override;
 
   void SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept override;
 

From 7ce23b94de35db44d098293a7d082864935b6876 Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Tue, 29 Sep 2020 01:39:31 +0530
Subject: [PATCH 5/8]  add test

---
 sdk/test/trace/tracer_test.cc | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index ba196c67c1..5c5fff3fc7 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -1,4 +1,5 @@
 #include "opentelemetry/sdk/trace/tracer.h"
+#include "opentelemetry/sdk/trace/link.h"
 #include "opentelemetry/sdk/trace/samplers/always_off.h"
 #include "opentelemetry/sdk/trace/samplers/always_on.h"
 #include "opentelemetry/sdk/trace/samplers/parent_or_else.h"
@@ -341,6 +342,24 @@ TEST(Tracer, SpanSetAttribute)
   ASSERT_EQ(3.1, nostd::get<double>(span_data->GetAttributes().at("abc")));
 }
 
+TEST(Tracer, SpanAddLink)
+{
+  std::shared_ptr<std::vector<std::unique_ptr<SpanData>>> spans_received(
+      new std::vector<std::unique_ptr<SpanData>>);
+  auto tracer = initTracer(spans_received);
+
+  auto span = tracer->StartSpan("span 1");
+
+  SpanContext sp1(true, true);
+  span->AddLink(sp1);
+
+  span->End();
+  ASSERT_EQ(1, spans_received->size());
+  auto &span_data = spans_received->at(0);
+
+  ASSERT_EQ(1, span_data->GetLinks().size());
+}
+
 TEST(Tracer, TestAlwaysOnSampler)
 {
   std::shared_ptr<std::vector<std::unique_ptr<SpanData>>> spans_received(

From fc5b652e1f4b194ea438e6bd799a504e62a37f69 Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Tue, 29 Sep 2020 12:55:56 +0530
Subject: [PATCH 6/8]  review comment

---
 api/include/opentelemetry/plugin/tracer.h     |  9 ++++++---
 .../opentelemetry/trace/default_span.h        |  4 ++--
 api/include/opentelemetry/trace/noop.h        |  4 ++--
 api/include/opentelemetry/trace/span.h        | 19 +++++++++++++++++--
 examples/plugin/plugin/tracer.cc              |  4 ++--
 .../ext/zpages/threadsafe_span_data.h         |  2 +-
 .../opentelemetry/sdk/trace/recordable.h      |  4 ++--
 .../opentelemetry/sdk/trace/span_data.h       |  4 ++--
 sdk/src/trace/span.cc                         |  8 ++++----
 sdk/src/trace/span.h                          |  4 ++--
 10 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index e9c333dccf..cb1c4b4e1a 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -39,13 +39,16 @@ class Span final : public trace::Span
   }
 
   void AddLink(const trace::Link &link) noexcept override { span_->AddLink(link); }
-  void AddLink(trace::SpanContext spanContext,
+  void AddLink(const trace::SpanContext &span_context,
                const trace::KeyValueIterable &attributes) noexcept override
   {
-    span_->AddLink(spanContext, attributes);
+    span_->AddLink(span_context, attributes);
   }
 
-  void AddLink(trace::SpanContext spanContext) noexcept override { span_->AddLink(spanContext); }
+  void AddLink(const trace::SpanContext &span_context) noexcept override
+  {
+    span_->AddLink(span_context);
+  }
 
   void SetStatus(trace::CanonicalCode code, nostd::string_view description) noexcept override
   {
diff --git a/api/include/opentelemetry/trace/default_span.h b/api/include/opentelemetry/trace/default_span.h
index b9e129ef49..3b31c67b3d 100644
--- a/api/include/opentelemetry/trace/default_span.h
+++ b/api/include/opentelemetry/trace/default_span.h
@@ -35,11 +35,11 @@ class DefaultSpan : public Span
 
   void AddLink(const trace::Link &link) noexcept override {}
 
-  void AddLink(trace::SpanContext spanContext,
+  void AddLink(const trace::SpanContext &span_context,
                const trace::KeyValueIterable &attributes) noexcept override
   {}
 
-  void AddLink(trace::SpanContext spanContext) noexcept override {}
+  void AddLink(const trace::SpanContext &span_context) noexcept override {}
 
   void SetStatus(CanonicalCode status, nostd::string_view description) noexcept {}
 
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 60c3896840..cc18288a7c 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -42,11 +42,11 @@ class NoopSpan final : public Span
 
   void AddLink(const Link &link) noexcept override {}
 
-  void AddLink(trace_api::SpanContext spanContext,
+  void AddLink(const trace_api::SpanContext &spanContext,
                const trace_api::KeyValueIterable &attributes) noexcept override
   {}
 
-  void AddLink(trace_api::SpanContext spanContext) noexcept override {}
+  void AddLink(const trace_api::SpanContext &span_context) noexcept override {}
 
   void SetStatus(CanonicalCode /*code*/, nostd::string_view /*description*/) noexcept override {}
 
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 50215ebc81..01cd2d74af 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -143,10 +143,25 @@ class Span
 
   virtual void AddLink(const trace::Link &link) noexcept = 0;
 
-  virtual void AddLink(trace::SpanContext spanContext,
+  virtual void AddLink(const trace::SpanContext &span_context,
                        const trace::KeyValueIterable &attributes) noexcept = 0;
 
-  virtual void AddLink(trace::SpanContext spanContext) noexcept = 0;
+  virtual void AddLink(const trace::SpanContext &span_context) noexcept = 0;
+
+  template <class T, nostd::enable_if_t<detail::is_key_value_iterable<T>::value> * = nullptr>
+  void AddLink(const trace::SpanContext &span_context, const T &attributes) noexcept
+  {
+    this->AddLink(span_context, KeyValueIterableView<T>{attributes});
+  }
+
+  void AddLink(const trace::SpanContext &span_context,
+               std::initializer_list<std::pair<nostd::string_view, common::AttributeValue>>
+                   attributes) noexcept
+  {
+    this->AddLink(span_context,
+                  nostd::span<const std::pair<nostd::string_view, common::AttributeValue>>{
+                      attributes.begin(), attributes.end()});
+  }
 
   // Sets the status of the span. The default status is OK. Only the value of
   // the last call will be
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index bad5420e6b..dff22598b9 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -44,11 +44,11 @@ class Span final : public trace::Span
 
   void AddLink(const trace::Link &link) noexcept override {}
 
-  void AddLink(trace::SpanContext spanContext,
+  void AddLink(const trace::SpanContext &span_context,
                const trace::KeyValueIterable &attributes) noexcept override
   {}
 
-  void AddLink(trace::SpanContext spanContext) noexcept override {}
+  void AddLink(const trace::SpanContext &span_context) noexcept override {}
 
   void SetStatus(trace::CanonicalCode /*code*/,
                  nostd::string_view /*description*/) noexcept override
diff --git a/ext/include/opentelemetry/ext/zpages/threadsafe_span_data.h b/ext/include/opentelemetry/ext/zpages/threadsafe_span_data.h
index 1c7595aae6..60301b2288 100644
--- a/ext/include/opentelemetry/ext/zpages/threadsafe_span_data.h
+++ b/ext/include/opentelemetry/ext/zpages/threadsafe_span_data.h
@@ -163,7 +163,7 @@ class ThreadsafeSpanData final : public opentelemetry::sdk::trace::Recordable
   }
 
   void AddLink(
-      opentelemetry::trace::SpanContext span_context,
+      const opentelemetry::trace::SpanContext &span_context,
       const trace_api::KeyValueIterable &attributes =
           trace_api::KeyValueIterableView<std::map<std::string, int>>({})) noexcept override
   {
diff --git a/sdk/include/opentelemetry/sdk/trace/recordable.h b/sdk/include/opentelemetry/sdk/trace/recordable.h
index 68124db0e6..7653b3a0cb 100644
--- a/sdk/include/opentelemetry/sdk/trace/recordable.h
+++ b/sdk/include/opentelemetry/sdk/trace/recordable.h
@@ -82,14 +82,14 @@ class Recordable
    * @param span_context the span context of the linked span
    * @param attributes the attributes associated with the link
    */
-  virtual void AddLink(opentelemetry::trace::SpanContext span_context,
+  virtual void AddLink(const opentelemetry::trace::SpanContext &span_context,
                        const trace_api::KeyValueIterable &attributes) noexcept = 0;
 
   /**
    * Add a link to a span with default (empty) attributes.
    * @param span_context the span context of the linked span
    */
-  void AddLink(opentelemetry::trace::SpanContext span_context)
+  void AddLink(const opentelemetry::trace::SpanContext &span_context)
   {
     AddLink(span_context, opentelemetry::sdk::GetEmptyAttributes());
   }
diff --git a/sdk/include/opentelemetry/sdk/trace/span_data.h b/sdk/include/opentelemetry/sdk/trace/span_data.h
index b745a3f33f..82c3ac95d4 100644
--- a/sdk/include/opentelemetry/sdk/trace/span_data.h
+++ b/sdk/include/opentelemetry/sdk/trace/span_data.h
@@ -63,7 +63,7 @@ class SpanDataEvent
 class SpanDataLink
 {
 public:
-  SpanDataLink(opentelemetry::trace::SpanContext span_context,
+  SpanDataLink(const opentelemetry::trace::SpanContext &span_context,
                const trace_api::KeyValueIterable &attributes)
       : span_context_(span_context), attribute_map_(attributes)
   {}
@@ -180,7 +180,7 @@ class SpanData final : public Recordable
     events_.push_back(event);
   }
 
-  void AddLink(opentelemetry::trace::SpanContext span_context,
+  void AddLink(const opentelemetry::trace::SpanContext &span_context,
                const trace_api::KeyValueIterable &attributes) noexcept override
   {
     SpanDataLink link(span_context, attributes);
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 512f88292c..79bc3a9264 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -152,23 +152,23 @@ void Span::AddLink(const trace_api::Link &link) noexcept
   recordable_->AddLink(link.GetContext(), link.GetAttributes());
 }
 
-void Span::AddLink(trace_api::SpanContext spanContext,
+void Span::AddLink(const trace_api::SpanContext &span_context,
                    const trace_api::KeyValueIterable &attributes) noexcept
 {
   if (recordable_ == nullptr)
   {
     return;
   }
-  recordable_->AddLink(spanContext, attributes);
+  recordable_->AddLink(span_context, attributes);
 }
 
-void Span::AddLink(trace_api::SpanContext spanContext) noexcept
+void Span::AddLink(const trace_api::SpanContext &span_context) noexcept
 {
   if (recordable_ == nullptr)
   {
     return;
   }
-  recordable_->AddLink(spanContext);
+  recordable_->AddLink(span_context);
 }
 
 void Span::SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index 493778bdd3..09041b1ff1 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -39,10 +39,10 @@ class Span final : public trace_api::Span
 
   void AddLink(const trace_api::Link &link) noexcept override;
 
-  void AddLink(trace_api::SpanContext spanContext,
+  void AddLink(const trace_api::SpanContext &span_context,
                const trace_api::KeyValueIterable &attributes) noexcept override;
 
-  void AddLink(trace_api::SpanContext spanContext) noexcept override;
+  void AddLink(const trace_api::SpanContext &span_context) noexcept override;
 
   void SetStatus(trace_api::CanonicalCode code, nostd::string_view description) noexcept override;
 

From 92be8823f1758f78ff15421132bc3935a9ef1a1b Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Tue, 29 Sep 2020 13:28:09 +0530
Subject: [PATCH 7/8]  more tests

---
 api/test/trace/noop_test.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/api/test/trace/noop_test.cc b/api/test/trace/noop_test.cc
index d1f571becf..7de08f6204 100644
--- a/api/test/trace/noop_test.cc
+++ b/api/test/trace/noop_test.cc
@@ -39,6 +39,7 @@ TEST(NoopTest, UseNoopTracers)
   opentelemetry::trace::KeyValueIterableView<M> iterable{m1};
 
   s1->AddLink(sp, iterable);
+  s1->AddLink(sp, {{"abc", "123"}, {"xyz", "456"}});
 
   EXPECT_EQ(s1->IsRecording(), false);
 

From dce36566576272f68a1093505b7cd121becb45d3 Mon Sep 17 00:00:00 2001
From: Lalit Bhasin <labhas@microsoft.com>
Date: Tue, 29 Sep 2020 13:36:20 +0530
Subject: [PATCH 8/8]  add comment for span creation

---
 api/include/opentelemetry/trace/span.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 01cd2d74af..1c575ce5a8 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -139,6 +139,10 @@ class Span
   /** Adds a Link to newly created Span
    *  @param spanContext the context of the linked span
    *  @param attributes Link attributes
+   *
+   *  These methods need to be called immediately after Span
+   *  creation. Specification doesn't allow adding links after
+   *  span creation.
    */
 
   virtual void AddLink(const trace::Link &link) noexcept = 0;