From 39e26d28f58979d395363bd2eff1e94e5f935690 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Mon, 15 Jun 2020 17:53:23 -0700
Subject: [PATCH 01/18] Add SetAttribute method

---
 api/include/opentelemetry/plugin/tracer.h        | 5 +++++
 api/include/opentelemetry/trace/noop.h           | 4 ++++
 api/include/opentelemetry/trace/span.h           | 7 ++-----
 sdk/include/opentelemetry/sdk/trace/recordable.h | 9 +++++++++
 sdk/include/opentelemetry/sdk/trace/span_data.h  | 6 ++++++
 sdk/src/trace/span.cc                            | 6 ++++++
 sdk/src/trace/span.h                             | 1 +
 7 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index 3d308e5826..a49a86f3b5 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -18,6 +18,11 @@ class Span final : public trace::Span
   {}
 
   // trace::Span
+  void SetAttribute(nostd::string_view name, common::AttributeValue &&value) noexcept override
+  {
+    span_->SetAttribute(name, std::move(value));
+  }
+
   void AddEvent(nostd::string_view name) noexcept override { span_->AddEvent(name); }
 
   void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept override
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 50dcc8b558..59768bb263 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -24,6 +24,10 @@ class NoopSpan final : public Span
 public:
   explicit NoopSpan(const std::shared_ptr<Tracer> &tracer) noexcept : tracer_{tracer} {}
 
+  void SetAttribute(nostd::string_view /*key*/,
+                    common::AttributeValue && /*value*/) noexcept override
+  {}
+
   void AddEvent(nostd::string_view /*name*/) noexcept override {}
 
   void AddEvent(nostd::string_view /*name*/, core::SystemTimestamp /*timestamp*/) noexcept override
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 21ed1aaaff..b53b40b305 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -2,6 +2,7 @@
 
 #include <cstdint>
 
+#include "opentelemetry/common/attribute_value.h"
 #include "opentelemetry/core/timestamp.h"
 #include "opentelemetry/nostd/span.h"
 #include "opentelemetry/nostd/string_view.h"
@@ -74,13 +75,9 @@ class Span
   Span &operator=(const Span &) = delete;
   Span &operator=(Span &&) = delete;
 
-  // TODO
   // Sets an attribute on the Span. If the Span previously contained a mapping for
   // the key, the old value is replaced.
-  //
-  // If an empty string is used as the value, the attribute will be silently
-  // dropped. Note: this behavior could change in the future.
-  // virtual void SetAttribute(nostd::string_view key, AttributeValue&& value) = 0;
+  virtual void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept = 0;
 
   // Adds an event to the Span.
   virtual void AddEvent(nostd::string_view name) noexcept = 0;
diff --git a/sdk/include/opentelemetry/sdk/trace/recordable.h b/sdk/include/opentelemetry/sdk/trace/recordable.h
index c102958fe3..e48939903f 100644
--- a/sdk/include/opentelemetry/sdk/trace/recordable.h
+++ b/sdk/include/opentelemetry/sdk/trace/recordable.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "opentelemetry/common/attribute_value.h"
 #include "opentelemetry/core/timestamp.h"
 #include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/trace/canonical_code.h"
@@ -33,6 +34,14 @@ class Recordable
                       opentelemetry::trace::SpanId span_id,
                       opentelemetry::trace::SpanId parent_span_id) noexcept = 0;
 
+  /**
+   * Add an attribute to a span.
+   * @param name the name of the attribute
+   * @param value the attribute value
+   */
+  virtual void SetAttribute(nostd::string_view key,
+                            opentelemetry::common::AttributeValue &&value) noexcept = 0;
+
   /**
    * Add an event to a span.
    * @param name the name of the event
diff --git a/sdk/include/opentelemetry/sdk/trace/span_data.h b/sdk/include/opentelemetry/sdk/trace/span_data.h
index 8ac620ad1b..8b9f5f7e77 100644
--- a/sdk/include/opentelemetry/sdk/trace/span_data.h
+++ b/sdk/include/opentelemetry/sdk/trace/span_data.h
@@ -76,6 +76,12 @@ class SpanData final : public Recordable
     parent_span_id_ = parent_span_id;
   }
 
+  void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept override
+  {
+    (void)key;
+    (void)value;
+  }
+
   void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept override
   {
     (void)name;
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index a69e6673b0..ba5a281b64 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -64,6 +64,12 @@ Span::~Span()
   End();
 }
 
+void Span::SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept
+{
+  (void)key;
+  (void)value;
+}
+
 void Span::AddEvent(nostd::string_view name) noexcept
 {
   (void)name;
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index e1a6f2084a..22e5486234 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -23,6 +23,7 @@ class Span final : public trace_api::Span
   ~Span() override;
 
   // trace_api::Span
+  void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept override;
   void AddEvent(nostd::string_view name) noexcept override;
 
   void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept override;

From f9d8c7e4006256f07509643acffe0989914d855c Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Mon, 15 Jun 2020 18:17:46 -0700
Subject: [PATCH 02/18] Add to span data

---
 sdk/include/opentelemetry/sdk/trace/span_data.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/sdk/include/opentelemetry/sdk/trace/span_data.h b/sdk/include/opentelemetry/sdk/trace/span_data.h
index 8b9f5f7e77..6e18c2dd26 100644
--- a/sdk/include/opentelemetry/sdk/trace/span_data.h
+++ b/sdk/include/opentelemetry/sdk/trace/span_data.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <chrono>
+#include <map>
 #include "opentelemetry/core/timestamp.h"
 #include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/sdk/trace/recordable.h"
@@ -67,6 +68,15 @@ class SpanData final : public Recordable
    */
   std::chrono::nanoseconds GetDuration() const noexcept { return duration_; }
 
+  /**
+   * Get the duration for this span
+   * @return the duration for this span
+   */
+  const std::map<std::string, common::AttributeValue>& GetAttributes() const noexcept
+  {
+      return attributes_;
+  }
+
   void SetIds(opentelemetry::trace::TraceId trace_id,
               opentelemetry::trace::SpanId span_id,
               opentelemetry::trace::SpanId parent_span_id) noexcept override
@@ -78,8 +88,7 @@ class SpanData final : public Recordable
 
   void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept override
   {
-    (void)key;
-    (void)value;
+    attributes_[std::string(key)] = value;
   }
 
   void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept override
@@ -112,6 +121,7 @@ class SpanData final : public Recordable
   std::string name_;
   opentelemetry::trace::CanonicalCode status_code_{opentelemetry::trace::CanonicalCode::OK};
   std::string status_desc_;
+  std::map<std::string, common::AttributeValue> attributes_;
 };
 }  // namespace trace
 }  // namespace sdk

From 3de6cbffa7f1e2ecfe0f2de2af016ecb4ea11356 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 11:36:20 -0700
Subject: [PATCH 03/18] Add SDK support for attributes

---
 sdk/include/opentelemetry/sdk/trace/span_data.h | 10 +++++-----
 sdk/src/trace/span.cc                           |  3 +--
 sdk/src/trace/span.h                            |  1 +
 sdk/test/trace/span_data_test.cc                |  4 ++++
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/sdk/include/opentelemetry/sdk/trace/span_data.h b/sdk/include/opentelemetry/sdk/trace/span_data.h
index 6e18c2dd26..e8ed974bf5 100644
--- a/sdk/include/opentelemetry/sdk/trace/span_data.h
+++ b/sdk/include/opentelemetry/sdk/trace/span_data.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <chrono>
-#include <map>
+#include <unordered_map>
 #include "opentelemetry/core/timestamp.h"
 #include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/sdk/trace/recordable.h"
@@ -69,10 +69,10 @@ class SpanData final : public Recordable
   std::chrono::nanoseconds GetDuration() const noexcept { return duration_; }
 
   /**
-   * Get the duration for this span
-   * @return the duration for this span
+   * Get the attributes for this span
+   * @return the attributes for this span
    */
-  const std::map<std::string, common::AttributeValue>& GetAttributes() const noexcept
+  const std::unordered_map<std::string, common::AttributeValue>& GetAttributes() const noexcept
   {
       return attributes_;
   }
@@ -121,7 +121,7 @@ class SpanData final : public Recordable
   std::string name_;
   opentelemetry::trace::CanonicalCode status_code_{opentelemetry::trace::CanonicalCode::OK};
   std::string status_desc_;
-  std::map<std::string, common::AttributeValue> attributes_;
+  std::unordered_map<std::string, common::AttributeValue> attributes_;
 };
 }  // namespace trace
 }  // namespace sdk
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index ba5a281b64..e774f7280d 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -66,8 +66,7 @@ Span::~Span()
 
 void Span::SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept
 {
-  (void)key;
-  (void)value;
+  recordable_->SetAttribute(key, std::move(value));
 }
 
 void Span::AddEvent(nostd::string_view name) noexcept
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index 22e5486234..bbbf2032cb 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -24,6 +24,7 @@ class Span final : public trace_api::Span
 
   // trace_api::Span
   void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept override;
+
   void AddEvent(nostd::string_view name) noexcept override;
 
   void AddEvent(nostd::string_view name, core::SystemTimestamp timestamp) noexcept override;
diff --git a/sdk/test/trace/span_data_test.cc b/sdk/test/trace/span_data_test.cc
index ea8aab446c..6176042c03 100644
--- a/sdk/test/trace/span_data_test.cc
+++ b/sdk/test/trace/span_data_test.cc
@@ -1,3 +1,4 @@
+#include "opentelemetry/nostd/variant.h"
 #include "opentelemetry/sdk/trace/span_data.h"
 #include "opentelemetry/trace/span_id.h"
 #include "opentelemetry/trace/trace_id.h"
@@ -20,6 +21,7 @@ TEST(SpanData, DefaultValues)
   ASSERT_EQ(data.GetDescription(), "");
   ASSERT_EQ(data.GetStartTime().time_since_epoch(), std::chrono::nanoseconds(0));
   ASSERT_EQ(data.GetDuration(), std::chrono::nanoseconds(0));
+  ASSERT_EQ(data.GetAttributes().size(), 0);
 }
 
 TEST(SpanData, Set)
@@ -35,6 +37,7 @@ TEST(SpanData, Set)
   data.SetStatus(opentelemetry::trace::CanonicalCode::UNKNOWN, "description");
   data.SetStartTime(now);
   data.SetDuration(std::chrono::nanoseconds(1000000));
+  data.SetAttribute("attr1", 314159);
   data.AddEvent("event1", now);
 
   ASSERT_EQ(data.GetTraceId(), trace_id);
@@ -45,4 +48,5 @@ TEST(SpanData, Set)
   ASSERT_EQ(data.GetDescription(), "description");
   ASSERT_EQ(data.GetStartTime().time_since_epoch(), now.time_since_epoch());
   ASSERT_EQ(data.GetDuration(), std::chrono::nanoseconds(1000000));
+  ASSERT_EQ(opentelemetry::nostd::get<int>(data.GetAttributes().at("attr1")), 314159);
 }

From c300da60aac5379bc2f91fb94b2a6bce02819b57 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 13:33:12 -0700
Subject: [PATCH 04/18] Add tests

---
 api/include/opentelemetry/trace/span.h |  1 +
 sdk/src/trace/span.cc                  |  5 +++++
 sdk/test/trace/tracer_test.cc          | 27 +++++++++++++++++++++++++-
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index b53b40b305..069592e63d 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -42,6 +42,7 @@ struct StartSpanOptions
   // SpanContext remote_parent;
   // Links
   // Attributes
+  nostd::span<std::pair<nostd::string_view, common::AttributeValue>> attributes;
   SpanKind kind = SpanKind::kInternal;
 };
 /**
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index e774f7280d..a9c6275ec7 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -55,6 +55,11 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
   processor_->OnStart(*recordable_);
   recordable_->SetName(name);
 
+  for (auto& attr : options.attributes) {
+      auto value = attr.second;
+      recordable_->SetAttribute(attr.first, std::move(value));
+  }
+
   recordable_->SetStartTime(NowOr(options.start_system_time));
   start_steady_time = NowOr(options.start_steady_time);
 }
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index e0bc2afde6..a6ac26aa5a 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -91,7 +91,7 @@ TEST(Tracer, StartSpan)
   ASSERT_LT(std::chrono::nanoseconds(0), span_data->GetDuration());
 }
 
-TEST(Tracer, StartSpanWithOptions)
+TEST(Tracer, StartSpanWithOptionsTime)
 {
   std::shared_ptr<std::vector<std::unique_ptr<SpanData>>> spans_received(
       new std::vector<std::unique_ptr<SpanData>>);
@@ -112,3 +112,28 @@ TEST(Tracer, StartSpanWithOptions)
   ASSERT_EQ(std::chrono::nanoseconds(300), span_data->GetStartTime().time_since_epoch());
   ASSERT_EQ(std::chrono::nanoseconds(30), span_data->GetDuration());
 }
+
+TEST(Tracer, StartSpanWithOptionsAttributes)
+{
+  std::shared_ptr<std::vector<std::unique_ptr<SpanData>>> spans_received(
+      new std::vector<std::unique_ptr<SpanData>>);
+  auto tracer = initTracer(spans_received);
+
+  opentelemetry::trace::StartSpanOptions start;
+  std::pair<opentelemetry::nostd::string_view, opentelemetry::common::AttributeValue> attributes[] = { 
+      {"attr1", 314159},
+      {"attr2", false}, 
+      {"attr3", "hi"} 
+  };
+  start.attributes = attributes;
+
+  tracer->StartSpan("span 1", start)->End();
+
+  ASSERT_EQ(1, spans_received->size());
+
+  auto &span_data = spans_received->at(0);
+  ASSERT_EQ(3, span_data->GetAttributes().size());
+  ASSERT_EQ(314159, opentelemetry::nostd::get<int>(span_data->GetAttributes().at("attr1")));
+  ASSERT_EQ(false, opentelemetry::nostd::get<bool>(span_data->GetAttributes().at("attr2")));
+  ASSERT_EQ("hi", opentelemetry::nostd::get<opentelemetry::nostd::string_view>(span_data->GetAttributes().at("attr3")));
+}

From f07d893914d4a141eaf1fa28c90ddad993fc7897 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 14:33:45 -0700
Subject: [PATCH 05/18] Set attributes on span start

---
 api/include/opentelemetry/trace/span.h         |  5 +++--
 examples/plugin/plugin/tracer.cc               | 11 ++++++++---
 .../opentelemetry/sdk/trace/span_data.h        |  4 ++--
 sdk/src/trace/span.cc                          |  7 ++++---
 sdk/test/trace/span_data_test.cc               |  2 +-
 sdk/test/trace/tracer_test.cc                  | 18 ++++++++----------
 6 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 069592e63d..8ecf192c56 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -37,12 +37,13 @@ struct StartSpanOptions
   core::SystemTimestamp start_system_time;
   core::SteadyTimestamp start_steady_time;
 
+  // Optionally set attributes at Span creation.
+  nostd::span<std::pair<nostd::string_view, common::AttributeValue>> attributes;
+
   // TODO:
   // Span(Context?) parent;
   // SpanContext remote_parent;
   // Links
-  // Attributes
-  nostd::span<std::pair<nostd::string_view, common::AttributeValue>> attributes;
   SpanKind kind = SpanKind::kInternal;
 };
 /**
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index c6e646d5d0..f62cb1fa4b 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -2,9 +2,10 @@
 
 #include <iostream>
 
-namespace nostd = opentelemetry::nostd;
-namespace core  = opentelemetry::core;
-namespace trace = opentelemetry::trace;
+namespace nostd  = opentelemetry::nostd;
+namespace common = opentelemetry::common;
+namespace core   = opentelemetry::core;
+namespace trace  = opentelemetry::trace;
 
 namespace
 {
@@ -22,6 +23,10 @@ class Span final : public trace::Span
   ~Span() { std::cout << "~Span\n"; }
 
   // opentelemetry::trace::Span
+  void SetAttribute(nostd::string_view /*name*/,
+                    common::AttributeValue && /*value*/) noexcept override
+  {}
+
   void AddEvent(nostd::string_view /*name*/) noexcept override {}
 
   void AddEvent(nostd::string_view /*name*/, core::SystemTimestamp /*timestamp*/) noexcept override
diff --git a/sdk/include/opentelemetry/sdk/trace/span_data.h b/sdk/include/opentelemetry/sdk/trace/span_data.h
index e8ed974bf5..5fab63c5ab 100644
--- a/sdk/include/opentelemetry/sdk/trace/span_data.h
+++ b/sdk/include/opentelemetry/sdk/trace/span_data.h
@@ -72,9 +72,9 @@ class SpanData final : public Recordable
    * Get the attributes for this span
    * @return the attributes for this span
    */
-  const std::unordered_map<std::string, common::AttributeValue>& GetAttributes() const noexcept
+  const std::unordered_map<std::string, common::AttributeValue> &GetAttributes() const noexcept
   {
-      return attributes_;
+    return attributes_;
   }
 
   void SetIds(opentelemetry::trace::TraceId trace_id,
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index a9c6275ec7..923008c088 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -55,9 +55,10 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
   processor_->OnStart(*recordable_);
   recordable_->SetName(name);
 
-  for (auto& attr : options.attributes) {
-      auto value = attr.second;
-      recordable_->SetAttribute(attr.first, std::move(value));
+  for (auto &attr : options.attributes)
+  {
+    auto value = attr.second;
+    recordable_->SetAttribute(attr.first, std::move(value));
   }
 
   recordable_->SetStartTime(NowOr(options.start_system_time));
diff --git a/sdk/test/trace/span_data_test.cc b/sdk/test/trace/span_data_test.cc
index 6176042c03..7bf6c34ec1 100644
--- a/sdk/test/trace/span_data_test.cc
+++ b/sdk/test/trace/span_data_test.cc
@@ -1,5 +1,5 @@
-#include "opentelemetry/nostd/variant.h"
 #include "opentelemetry/sdk/trace/span_data.h"
+#include "opentelemetry/nostd/variant.h"
 #include "opentelemetry/trace/span_id.h"
 #include "opentelemetry/trace/trace_id.h"
 
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index a6ac26aa5a..227236f2f4 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -7,6 +7,8 @@
 using namespace opentelemetry::sdk::trace;
 using opentelemetry::core::SteadyTimestamp;
 using opentelemetry::core::SystemTimestamp;
+namespace nostd  = opentelemetry::nostd;
+namespace common = opentelemetry::common;
 
 /**
  * A mock exporter that switches a flag once a valid recordable was received.
@@ -23,8 +25,7 @@ class MockSpanExporter final : public SpanExporter
     return std::unique_ptr<Recordable>(new SpanData);
   }
 
-  ExportResult Export(
-      const opentelemetry::nostd::span<std::unique_ptr<Recordable>> &recordables) noexcept override
+  ExportResult Export(const nostd::span<std::unique_ptr<Recordable>> &recordables) noexcept override
   {
     for (auto &recordable : recordables)
     {
@@ -120,11 +121,8 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
   auto tracer = initTracer(spans_received);
 
   opentelemetry::trace::StartSpanOptions start;
-  std::pair<opentelemetry::nostd::string_view, opentelemetry::common::AttributeValue> attributes[] = { 
-      {"attr1", 314159},
-      {"attr2", false}, 
-      {"attr3", "hi"} 
-  };
+  std::pair<nostd::string_view, common::AttributeValue> attributes[] = {
+      {"attr1", 314159}, {"attr2", false}, {"attr3", "string"}};
   start.attributes = attributes;
 
   tracer->StartSpan("span 1", start)->End();
@@ -133,7 +131,7 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
 
   auto &span_data = spans_received->at(0);
   ASSERT_EQ(3, span_data->GetAttributes().size());
-  ASSERT_EQ(314159, opentelemetry::nostd::get<int>(span_data->GetAttributes().at("attr1")));
-  ASSERT_EQ(false, opentelemetry::nostd::get<bool>(span_data->GetAttributes().at("attr2")));
-  ASSERT_EQ("hi", opentelemetry::nostd::get<opentelemetry::nostd::string_view>(span_data->GetAttributes().at("attr3")));
+  ASSERT_EQ(314159, nostd::get<int>(span_data->GetAttributes().at("attr1")));
+  ASSERT_EQ(false, nostd::get<bool>(span_data->GetAttributes().at("attr2")));
+  ASSERT_EQ("string", nostd::get<nostd::string_view>(span_data->GetAttributes().at("attr3")));
 }

From 08d24a2cbfde0264158391b82c437422756bed03 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 15:20:03 -0700
Subject: [PATCH 06/18] Fix documentation

---
 api/include/opentelemetry/trace/span.h           | 5 ++++-
 sdk/include/opentelemetry/sdk/trace/recordable.h | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 8ecf192c56..c12b8abb2a 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -37,7 +37,10 @@ struct StartSpanOptions
   core::SystemTimestamp start_system_time;
   core::SteadyTimestamp start_steady_time;
 
-  // Optionally set attributes at Span creation.
+  // Optionally set 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::span<std::pair<nostd::string_view, common::AttributeValue>> attributes;
 
   // TODO:
diff --git a/sdk/include/opentelemetry/sdk/trace/recordable.h b/sdk/include/opentelemetry/sdk/trace/recordable.h
index e48939903f..ebb698f9de 100644
--- a/sdk/include/opentelemetry/sdk/trace/recordable.h
+++ b/sdk/include/opentelemetry/sdk/trace/recordable.h
@@ -35,7 +35,7 @@ class Recordable
                       opentelemetry::trace::SpanId parent_span_id) noexcept = 0;
 
   /**
-   * Add an attribute to a span.
+   * Set an attribute of a span.
    * @param name the name of the attribute
    * @param value the attribute value
    */

From d684dc6c4d1c10fdb717dc44775108f0bdee1a05 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 15:24:42 -0700
Subject: [PATCH 07/18] Add test for overwriting attributes

---
 sdk/test/trace/tracer_test.cc | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index 227236f2f4..f45344aea7 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -122,7 +122,7 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
 
   opentelemetry::trace::StartSpanOptions start;
   std::pair<nostd::string_view, common::AttributeValue> attributes[] = {
-      {"attr1", 314159}, {"attr2", false}, {"attr3", "string"}};
+      {"attr1", 314159}, {"attr2", false}, {"attr1", "string"}};
   start.attributes = attributes;
 
   tracer->StartSpan("span 1", start)->End();
@@ -130,8 +130,7 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
   ASSERT_EQ(1, spans_received->size());
 
   auto &span_data = spans_received->at(0);
-  ASSERT_EQ(3, span_data->GetAttributes().size());
-  ASSERT_EQ(314159, nostd::get<int>(span_data->GetAttributes().at("attr1")));
+  ASSERT_EQ(2, span_data->GetAttributes().size());
+  ASSERT_EQ("string", nostd::get<nostd::string_view>(span_data->GetAttributes().at("attr1")));
   ASSERT_EQ(false, nostd::get<bool>(span_data->GetAttributes().at("attr2")));
-  ASSERT_EQ("string", nostd::get<nostd::string_view>(span_data->GetAttributes().at("attr3")));
 }

From f4d6661adbfc443f3e92031c1db02085d4ed3b97 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 15:43:50 -0700
Subject: [PATCH 08/18] Update api/include/opentelemetry/trace/span.h

Co-authored-by: Reiley Yang <reyang@microsoft.com>
---
 api/include/opentelemetry/trace/span.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index c12b8abb2a..e706c66250 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -37,7 +37,7 @@ struct StartSpanOptions
   core::SystemTimestamp start_system_time;
   core::SteadyTimestamp start_steady_time;
 
-  // Optionally set attributes at Span creation from the given key/value pairs..
+  // Optionally set 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.

From 852be31d89a6e0eec9c44793ddd5b8adee141f9f Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Tue, 16 Jun 2020 16:10:08 -0700
Subject: [PATCH 09/18] Add lock for setting attributes

---
 sdk/src/trace/span.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 923008c088..4c660f533b 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -72,6 +72,8 @@ Span::~Span()
 
 void Span::SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept
 {
+  std::lock_guard<std::mutex> lock_guard{mu_};
+
   recordable_->SetAttribute(key, std::move(value));
 }
 

From 81b1f0323868eb2725862744db69dd8e6c39e3f8 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Wed, 17 Jun 2020 23:27:34 -0700
Subject: [PATCH 10/18] Use a struct for attribute key/value pairs

---
 api/include/opentelemetry/common/attribute_value.h | 8 ++++++++
 api/include/opentelemetry/trace/span.h             | 2 +-
 sdk/src/trace/span.cc                              | 4 ++--
 sdk/test/trace/tracer_test.cc                      | 2 +-
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/api/include/opentelemetry/common/attribute_value.h b/api/include/opentelemetry/common/attribute_value.h
index 6340a4f97c..90a00ef14a 100644
--- a/api/include/opentelemetry/common/attribute_value.h
+++ b/api/include/opentelemetry/common/attribute_value.h
@@ -24,5 +24,13 @@ using AttributeValue = nostd::variant<bool,
                                       nostd::span<const uint64_t>,
                                       nostd::span<const double>,
                                       nostd::span<const nostd::string_view>>;
+
+/**
+ * A key/value pair that can be used to set attributes.
+ */
+struct AttributeKeyValue {
+    nostd::string_view key;
+    AttributeValue value;
+};
 }  // namespace common
 OPENTELEMETRY_END_NAMESPACE
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index e706c66250..d6cb5ddeb7 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -41,7 +41,7 @@ struct StartSpanOptions
   //
   // Attributes will be processed in order, previous attributes with the same
   // key will be overwritten.
-  nostd::span<std::pair<nostd::string_view, common::AttributeValue>> attributes;
+  nostd::span<common::AttributeKeyValue> attributes;
 
   // TODO:
   // Span(Context?) parent;
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 4c660f533b..9f30a5c154 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -57,8 +57,8 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
 
   for (auto &attr : options.attributes)
   {
-    auto value = attr.second;
-    recordable_->SetAttribute(attr.first, std::move(value));
+    auto value = attr.value;
+    recordable_->SetAttribute(attr.key, std::move(value));
   }
 
   recordable_->SetStartTime(NowOr(options.start_system_time));
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index f45344aea7..d8a8550d6f 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -121,7 +121,7 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
   auto tracer = initTracer(spans_received);
 
   opentelemetry::trace::StartSpanOptions start;
-  std::pair<nostd::string_view, common::AttributeValue> attributes[] = {
+  common::AttributeKeyValue attributes[] = {
       {"attr1", 314159}, {"attr2", false}, {"attr1", "string"}};
   start.attributes = attributes;
 

From 9149aa12c8497abfd32dca42e253626acdc28ce8 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Fri, 19 Jun 2020 21:08:58 -0700
Subject: [PATCH 11/18] PR comments

---
 api/include/opentelemetry/common/attribute_value.h | 7 ++++---
 sdk/src/trace/span.cc                              | 3 +--
 sdk/test/trace/tracer_test.cc                      | 6 +++---
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/api/include/opentelemetry/common/attribute_value.h b/api/include/opentelemetry/common/attribute_value.h
index 90a00ef14a..8a6b0c1b39 100644
--- a/api/include/opentelemetry/common/attribute_value.h
+++ b/api/include/opentelemetry/common/attribute_value.h
@@ -28,9 +28,10 @@ using AttributeValue = nostd::variant<bool,
 /**
  * A key/value pair that can be used to set attributes.
  */
-struct AttributeKeyValue {
-    nostd::string_view key;
-    AttributeValue value;
+struct AttributeKeyValue
+{
+  nostd::string_view key;
+  AttributeValue value;
 };
 }  // namespace common
 OPENTELEMETRY_END_NAMESPACE
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 9f30a5c154..7647adfee0 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -57,8 +57,7 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
 
   for (auto &attr : options.attributes)
   {
-    auto value = attr.value;
-    recordable_->SetAttribute(attr.key, std::move(value));
+    recordable_->SetAttribute(attr.key, std::move(attr.value));
   }
 
   recordable_->SetStartTime(NowOr(options.start_system_time));
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index d8a8550d6f..932bfafbfb 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -120,12 +120,12 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
       new std::vector<std::unique_ptr<SpanData>>);
   auto tracer = initTracer(spans_received);
 
-  opentelemetry::trace::StartSpanOptions start;
+  opentelemetry::trace::StartSpanOptions opts;
   common::AttributeKeyValue attributes[] = {
       {"attr1", 314159}, {"attr2", false}, {"attr1", "string"}};
-  start.attributes = attributes;
+  opts.attributes = attributes;
 
-  tracer->StartSpan("span 1", start)->End();
+  tracer->StartSpan("span 1", opts)->End();
 
   ASSERT_EQ(1, spans_received->size());
 

From da1c5990e33ea8f085ed24d5de747093df1b6e49 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Sat, 20 Jun 2020 16:00:04 -0700
Subject: [PATCH 12/18] Attribute list

---
 api/include/opentelemetry/plugin/tracer.h    |  3 ++-
 api/include/opentelemetry/trace/noop.h       |  1 +
 api/include/opentelemetry/trace/span.h       |  1 -
 api/include/opentelemetry/trace/tracer.h     |  1 +
 examples/plugin/plugin/tracer.cc             |  4 +++-
 examples/plugin/plugin/tracer.h              |  3 ++-
 sdk/include/opentelemetry/sdk/trace/tracer.h |  1 +
 sdk/src/trace/span.cc                        |  3 ++-
 sdk/src/trace/span.h                         |  1 +
 sdk/src/trace/tracer.cc                      |  3 ++-
 sdk/test/trace/tracer_test.cc                | 11 +++++------
 11 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index a49a86f3b5..502a76e169 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -66,9 +66,10 @@ class Tracer final : public trace::Tracer, public std::enable_shared_from_this<T
   // trace::Tracer
   nostd::unique_ptr<trace::Span> StartSpan(
       nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes = {},
       const trace::StartSpanOptions &options = {}) noexcept override
   {
-    auto span = tracer_handle_->tracer().StartSpan(name, options);
+    auto span = tracer_handle_->tracer().StartSpan(name, attributes, options);
     if (span == nullptr)
     {
       return nullptr;
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 59768bb263..981b5540ff 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -60,6 +60,7 @@ class NoopTracer final : public Tracer, public std::enable_shared_from_this<Noop
 public:
   // Tracer
   nostd::unique_ptr<Span> StartSpan(nostd::string_view /*name*/,
+					    nostd::span<common::AttributeKeyValue> /* attributes */,
                                     const StartSpanOptions & /*options*/) noexcept override
   {
     return nostd::unique_ptr<Span>{new (std::nothrow) NoopSpan{this->shared_from_this()}};
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index d6cb5ddeb7..1ff8fe2999 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -41,7 +41,6 @@ struct StartSpanOptions
   //
   // Attributes will be processed in order, previous attributes with the same
   // key will be overwritten.
-  nostd::span<common::AttributeKeyValue> attributes;
 
   // TODO:
   // Span(Context?) parent;
diff --git a/api/include/opentelemetry/trace/tracer.h b/api/include/opentelemetry/trace/tracer.h
index 29aa288123..c6a85994aa 100644
--- a/api/include/opentelemetry/trace/tracer.h
+++ b/api/include/opentelemetry/trace/tracer.h
@@ -24,6 +24,7 @@ class Tracer
    * Starts a span.
    */
   virtual nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes = {},
                                             const StartSpanOptions &options = {}) noexcept = 0;
 
   /**
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index f62cb1fa4b..f6955a29a8 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -14,6 +14,7 @@ class Span final : public trace::Span
 public:
   Span(std::shared_ptr<Tracer> &&tracer,
        nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> /* attributes */,
        const trace::StartSpanOptions & /*options*/) noexcept
       : tracer_{std::move(tracer)}, name_{name}
   {
@@ -58,8 +59,9 @@ class Span final : public trace::Span
 Tracer::Tracer(nostd::string_view /*output*/) {}
 
 nostd::unique_ptr<trace::Span> Tracer::StartSpan(nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes,
                                                  const trace::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<opentelemetry::trace::Span>{
-      new (std::nothrow) Span{this->shared_from_this(), name, options}};
+      new (std::nothrow) Span{this->shared_from_this(), name, attributes, options}};
 }
diff --git a/examples/plugin/plugin/tracer.h b/examples/plugin/plugin/tracer.h
index 4d653f32e9..de15c32a0b 100644
--- a/examples/plugin/plugin/tracer.h
+++ b/examples/plugin/plugin/tracer.h
@@ -13,7 +13,8 @@ class Tracer final : public opentelemetry::trace::Tracer,
   // opentelemetry::trace::Tracer
   opentelemetry::nostd::unique_ptr<opentelemetry::trace::Span> StartSpan(
       opentelemetry::nostd::string_view name,
-      const opentelemetry::trace::StartSpanOptions &options) noexcept override;
+					    opentelemetry::nostd::span<opentelemetry::common::AttributeKeyValue> /* attributes */,
+      const opentelemetry::trace::StartSpanOptions & /*options */) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t /*timeout*/) noexcept override {}
 
diff --git a/sdk/include/opentelemetry/sdk/trace/tracer.h b/sdk/include/opentelemetry/sdk/trace/tracer.h
index 06c83b1058..e096e6be3e 100644
--- a/sdk/include/opentelemetry/sdk/trace/tracer.h
+++ b/sdk/include/opentelemetry/sdk/trace/tracer.h
@@ -37,6 +37,7 @@ class Tracer final : public trace_api::Tracer, public std::enable_shared_from_th
 
   nostd::unique_ptr<trace_api::Span> StartSpan(
       nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes = {},
       const trace_api::StartSpanOptions &options = {}) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t timeout) noexcept override;
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 7647adfee0..d9ef50d5b6 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -41,6 +41,7 @@ SteadyTimestamp NowOr(const SteadyTimestamp &steady)
 Span::Span(std::shared_ptr<Tracer> &&tracer,
            std::shared_ptr<SpanProcessor> processor,
            nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes,
            const trace_api::StartSpanOptions &options) noexcept
     : tracer_{std::move(tracer)},
       processor_{processor},
@@ -55,7 +56,7 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
   processor_->OnStart(*recordable_);
   recordable_->SetName(name);
 
-  for (auto &attr : options.attributes)
+  for (auto &attr : attributes)
   {
     recordable_->SetAttribute(attr.key, std::move(attr.value));
   }
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index bbbf2032cb..90cd673d4d 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -18,6 +18,7 @@ class Span final : public trace_api::Span
   explicit Span(std::shared_ptr<Tracer> &&tracer,
                 std::shared_ptr<SpanProcessor> processor,
                 nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes,
                 const trace_api::StartSpanOptions &options) noexcept;
 
   ~Span() override;
diff --git a/sdk/src/trace/tracer.cc b/sdk/src/trace/tracer.cc
index 15e89ceffd..a27ee3f1bf 100644
--- a/sdk/src/trace/tracer.cc
+++ b/sdk/src/trace/tracer.cc
@@ -21,10 +21,11 @@ std::shared_ptr<SpanProcessor> Tracer::GetProcessor() const noexcept
 
 nostd::unique_ptr<trace_api::Span> Tracer::StartSpan(
     nostd::string_view name,
+					    nostd::span<common::AttributeKeyValue> attributes,
     const trace_api::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<trace_api::Span>{
-      new (std::nothrow) Span{this->shared_from_this(), processor_.load(), name, options}};
+      new (std::nothrow) Span{this->shared_from_this(), processor_.load(), name, attributes, options}};
 }
 
 void Tracer::ForceFlushWithMicroseconds(uint64_t timeout) noexcept
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index 932bfafbfb..ec58671f12 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -105,7 +105,7 @@ TEST(Tracer, StartSpanWithOptionsTime)
   opentelemetry::trace::EndSpanOptions end;
   end.end_steady_time = SteadyTimestamp(std::chrono::nanoseconds(40));
 
-  tracer->StartSpan("span 1", start)->End(end);
+  tracer->StartSpan("span 1", {}, start)->End(end);
 
   ASSERT_EQ(1, spans_received->size());
 
@@ -120,12 +120,11 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
       new std::vector<std::unique_ptr<SpanData>>);
   auto tracer = initTracer(spans_received);
 
-  opentelemetry::trace::StartSpanOptions opts;
-  common::AttributeKeyValue attributes[] = {
-      {"attr1", 314159}, {"attr2", false}, {"attr1", "string"}};
-  opts.attributes = attributes;
 
-  tracer->StartSpan("span 1", opts)->End();
+  {
+      common::AttributeKeyValue attrs[] = {{"attr1", 314159}, {"attr2", false}, {"attr1", "string"}};
+      tracer->StartSpan("span 1", attrs);
+  }
 
   ASSERT_EQ(1, spans_received->size());
 

From bfc7ae06bb7c570847f366180140d233d87c238d Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Sun, 21 Jun 2020 12:46:14 -0700
Subject: [PATCH 13/18] Const

---
 api/include/opentelemetry/plugin/tracer.h        | 4 ++--
 api/include/opentelemetry/trace/noop.h           | 4 ++--
 api/include/opentelemetry/trace/span.h           | 2 +-
 api/include/opentelemetry/trace/tracer.h         | 2 +-
 examples/plugin/plugin/tracer.cc                 | 6 +++---
 examples/plugin/plugin/tracer.h                  | 2 +-
 sdk/include/opentelemetry/sdk/trace/recordable.h | 2 +-
 sdk/include/opentelemetry/sdk/trace/span_data.h  | 2 +-
 sdk/include/opentelemetry/sdk/trace/tracer.h     | 2 +-
 sdk/src/trace/span.cc                            | 4 ++--
 sdk/src/trace/span.h                             | 4 ++--
 sdk/src/trace/tracer.cc                          | 2 +-
 12 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index 502a76e169..b519706204 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -18,7 +18,7 @@ class Span final : public trace::Span
   {}
 
   // trace::Span
-  void SetAttribute(nostd::string_view name, common::AttributeValue &&value) noexcept override
+  void SetAttribute(nostd::string_view name, const common::AttributeValue &&value) noexcept override
   {
     span_->SetAttribute(name, std::move(value));
   }
@@ -66,7 +66,7 @@ class Tracer final : public trace::Tracer, public std::enable_shared_from_this<T
   // trace::Tracer
   nostd::unique_ptr<trace::Span> StartSpan(
       nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes = {},
+					    nostd::span<const common::AttributeKeyValue> attributes = {},
       const trace::StartSpanOptions &options = {}) noexcept override
   {
     auto span = tracer_handle_->tracer().StartSpan(name, attributes, options);
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 981b5540ff..0bc9f6ad81 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -25,7 +25,7 @@ class NoopSpan final : public Span
   explicit NoopSpan(const std::shared_ptr<Tracer> &tracer) noexcept : tracer_{tracer} {}
 
   void SetAttribute(nostd::string_view /*key*/,
-                    common::AttributeValue && /*value*/) noexcept override
+                    const common::AttributeValue && /*value*/) noexcept override
   {}
 
   void AddEvent(nostd::string_view /*name*/) noexcept override {}
@@ -60,7 +60,7 @@ class NoopTracer final : public Tracer, public std::enable_shared_from_this<Noop
 public:
   // Tracer
   nostd::unique_ptr<Span> StartSpan(nostd::string_view /*name*/,
-					    nostd::span<common::AttributeKeyValue> /* attributes */,
+					    nostd::span<const common::AttributeKeyValue> /* attributes */,
                                     const StartSpanOptions & /*options*/) noexcept override
   {
     return nostd::unique_ptr<Span>{new (std::nothrow) NoopSpan{this->shared_from_this()}};
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 1ff8fe2999..e6540cd43e 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -81,7 +81,7 @@ class Span
 
   // Sets an attribute on the Span. If the Span previously contained a mapping for
   // the key, the old value is replaced.
-  virtual void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept = 0;
+  virtual void SetAttribute(nostd::string_view key, const common::AttributeValue &&value) noexcept = 0;
 
   // Adds an event to the Span.
   virtual void AddEvent(nostd::string_view name) noexcept = 0;
diff --git a/api/include/opentelemetry/trace/tracer.h b/api/include/opentelemetry/trace/tracer.h
index c6a85994aa..34230f1e25 100644
--- a/api/include/opentelemetry/trace/tracer.h
+++ b/api/include/opentelemetry/trace/tracer.h
@@ -24,7 +24,7 @@ class Tracer
    * Starts a span.
    */
   virtual nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes = {},
+					    nostd::span<const common::AttributeKeyValue> attributes = {},
                                             const StartSpanOptions &options = {}) noexcept = 0;
 
   /**
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index f6955a29a8..2230f60d72 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -14,7 +14,7 @@ class Span final : public trace::Span
 public:
   Span(std::shared_ptr<Tracer> &&tracer,
        nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> /* attributes */,
+					    nostd::span<const common::AttributeKeyValue> /* attributes */,
        const trace::StartSpanOptions & /*options*/) noexcept
       : tracer_{std::move(tracer)}, name_{name}
   {
@@ -25,7 +25,7 @@ class Span final : public trace::Span
 
   // opentelemetry::trace::Span
   void SetAttribute(nostd::string_view /*name*/,
-                    common::AttributeValue && /*value*/) noexcept override
+                    const common::AttributeValue && /*value*/) noexcept override
   {}
 
   void AddEvent(nostd::string_view /*name*/) noexcept override {}
@@ -59,7 +59,7 @@ class Span final : public trace::Span
 Tracer::Tracer(nostd::string_view /*output*/) {}
 
 nostd::unique_ptr<trace::Span> Tracer::StartSpan(nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes,
+					    nostd::span<const common::AttributeKeyValue> attributes,
                                                  const trace::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<opentelemetry::trace::Span>{
diff --git a/examples/plugin/plugin/tracer.h b/examples/plugin/plugin/tracer.h
index de15c32a0b..07fdda9add 100644
--- a/examples/plugin/plugin/tracer.h
+++ b/examples/plugin/plugin/tracer.h
@@ -13,7 +13,7 @@ class Tracer final : public opentelemetry::trace::Tracer,
   // opentelemetry::trace::Tracer
   opentelemetry::nostd::unique_ptr<opentelemetry::trace::Span> StartSpan(
       opentelemetry::nostd::string_view name,
-					    opentelemetry::nostd::span<opentelemetry::common::AttributeKeyValue> /* attributes */,
+					    opentelemetry::nostd::span<const opentelemetry::common::AttributeKeyValue> /* attributes */,
       const opentelemetry::trace::StartSpanOptions & /*options */) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t /*timeout*/) noexcept override {}
diff --git a/sdk/include/opentelemetry/sdk/trace/recordable.h b/sdk/include/opentelemetry/sdk/trace/recordable.h
index ebb698f9de..d901dbfa54 100644
--- a/sdk/include/opentelemetry/sdk/trace/recordable.h
+++ b/sdk/include/opentelemetry/sdk/trace/recordable.h
@@ -40,7 +40,7 @@ class Recordable
    * @param value the attribute value
    */
   virtual void SetAttribute(nostd::string_view key,
-                            opentelemetry::common::AttributeValue &&value) noexcept = 0;
+                            const opentelemetry::common::AttributeValue &&value) noexcept = 0;
 
   /**
    * Add an event to a span.
diff --git a/sdk/include/opentelemetry/sdk/trace/span_data.h b/sdk/include/opentelemetry/sdk/trace/span_data.h
index 5fab63c5ab..c3b557dc9b 100644
--- a/sdk/include/opentelemetry/sdk/trace/span_data.h
+++ b/sdk/include/opentelemetry/sdk/trace/span_data.h
@@ -86,7 +86,7 @@ class SpanData final : public Recordable
     parent_span_id_ = parent_span_id;
   }
 
-  void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept override
+  void SetAttribute(nostd::string_view key, const common::AttributeValue &&value) noexcept override
   {
     attributes_[std::string(key)] = value;
   }
diff --git a/sdk/include/opentelemetry/sdk/trace/tracer.h b/sdk/include/opentelemetry/sdk/trace/tracer.h
index e096e6be3e..10b44d9043 100644
--- a/sdk/include/opentelemetry/sdk/trace/tracer.h
+++ b/sdk/include/opentelemetry/sdk/trace/tracer.h
@@ -37,7 +37,7 @@ class Tracer final : public trace_api::Tracer, public std::enable_shared_from_th
 
   nostd::unique_ptr<trace_api::Span> StartSpan(
       nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes = {},
+					    nostd::span<const common::AttributeKeyValue> attributes = {},
       const trace_api::StartSpanOptions &options = {}) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t timeout) noexcept override;
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index d9ef50d5b6..05fe42b6de 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -41,7 +41,7 @@ SteadyTimestamp NowOr(const SteadyTimestamp &steady)
 Span::Span(std::shared_ptr<Tracer> &&tracer,
            std::shared_ptr<SpanProcessor> processor,
            nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes,
+					    nostd::span<const common::AttributeKeyValue> attributes,
            const trace_api::StartSpanOptions &options) noexcept
     : tracer_{std::move(tracer)},
       processor_{processor},
@@ -70,7 +70,7 @@ Span::~Span()
   End();
 }
 
-void Span::SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept
+void Span::SetAttribute(nostd::string_view key, const common::AttributeValue &&value) noexcept
 {
   std::lock_guard<std::mutex> lock_guard{mu_};
 
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index 90cd673d4d..e7ff256604 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -18,13 +18,13 @@ class Span final : public trace_api::Span
   explicit Span(std::shared_ptr<Tracer> &&tracer,
                 std::shared_ptr<SpanProcessor> processor,
                 nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes,
+					    nostd::span<const common::AttributeKeyValue> attributes,
                 const trace_api::StartSpanOptions &options) noexcept;
 
   ~Span() override;
 
   // trace_api::Span
-  void SetAttribute(nostd::string_view key, common::AttributeValue &&value) noexcept override;
+  void SetAttribute(nostd::string_view key, const common::AttributeValue &&value) noexcept override;
 
   void AddEvent(nostd::string_view name) noexcept override;
 
diff --git a/sdk/src/trace/tracer.cc b/sdk/src/trace/tracer.cc
index a27ee3f1bf..fb4673f912 100644
--- a/sdk/src/trace/tracer.cc
+++ b/sdk/src/trace/tracer.cc
@@ -21,7 +21,7 @@ std::shared_ptr<SpanProcessor> Tracer::GetProcessor() const noexcept
 
 nostd::unique_ptr<trace_api::Span> Tracer::StartSpan(
     nostd::string_view name,
-					    nostd::span<common::AttributeKeyValue> attributes,
+					    nostd::span<const common::AttributeKeyValue> attributes,
     const trace_api::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<trace_api::Span>{

From 0b952af4760f330a267400497dadc74c0586edb0 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Sun, 21 Jun 2020 19:40:20 -0700
Subject: [PATCH 14/18] Change to KeyValueIterable

---
 api/include/opentelemetry/plugin/factory.h   |  4 +--
 api/include/opentelemetry/plugin/tracer.h    |  2 +-
 api/include/opentelemetry/trace/noop.h       |  2 +-
 api/include/opentelemetry/trace/tracer.h     | 23 +++++++++++++++-
 examples/plugin/load/main.cc                 |  1 +
 examples/plugin/plugin/tracer.cc             |  4 +--
 examples/plugin/plugin/tracer.h              |  2 +-
 sdk/include/opentelemetry/sdk/trace/tracer.h |  2 +-
 sdk/src/trace/span.cc                        | 10 +++----
 sdk/src/trace/span.h                         |  2 +-
 sdk/src/trace/tracer.cc                      |  2 +-
 sdk/test/trace/tracer_test.cc                | 28 +++++++++++++++-----
 12 files changed, 60 insertions(+), 22 deletions(-)

diff --git a/api/include/opentelemetry/plugin/factory.h b/api/include/opentelemetry/plugin/factory.h
index dd849335e7..60e8f5ab3b 100644
--- a/api/include/opentelemetry/plugin/factory.h
+++ b/api/include/opentelemetry/plugin/factory.h
@@ -36,7 +36,7 @@ class Factory final
    * @param error_message on failure this will contain an error message.
    * @return a Tracer on success or nullptr on failure.
    */
-  std::shared_ptr<Tracer> MakeTracer(nostd::string_view tracer_config,
+  std::shared_ptr<opentelemetry::trace::Tracer> MakeTracer(nostd::string_view tracer_config,
                                      std::string &error_message) const noexcept
   {
     nostd::unique_ptr<char[]> plugin_error_message;
@@ -46,7 +46,7 @@ class Factory final
       detail::CopyErrorMessage(plugin_error_message.get(), error_message);
       return nullptr;
     }
-    return std::shared_ptr<Tracer>{new (std::nothrow)
+    return std::shared_ptr<opentelemetry::trace::Tracer>{new (std::nothrow)
                                        Tracer{library_handle_, std::move(tracer_handle)}};
   }
 
diff --git a/api/include/opentelemetry/plugin/tracer.h b/api/include/opentelemetry/plugin/tracer.h
index b519706204..9970e5a533 100644
--- a/api/include/opentelemetry/plugin/tracer.h
+++ b/api/include/opentelemetry/plugin/tracer.h
@@ -66,7 +66,7 @@ class Tracer final : public trace::Tracer, public std::enable_shared_from_this<T
   // trace::Tracer
   nostd::unique_ptr<trace::Span> StartSpan(
       nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes = {},
+      const trace::KeyValueIterable &attributes,
       const trace::StartSpanOptions &options = {}) noexcept override
   {
     auto span = tracer_handle_->tracer().StartSpan(name, attributes, options);
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 0bc9f6ad81..423f40dca5 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -60,7 +60,7 @@ class NoopTracer final : public Tracer, public std::enable_shared_from_this<Noop
 public:
   // Tracer
   nostd::unique_ptr<Span> StartSpan(nostd::string_view /*name*/,
-					    nostd::span<const common::AttributeKeyValue> /* attributes */,
+					    const KeyValueIterable & /*attributes*/,
                                     const StartSpanOptions & /*options*/) noexcept override
   {
     return nostd::unique_ptr<Span>{new (std::nothrow) NoopSpan{this->shared_from_this()}};
diff --git a/api/include/opentelemetry/trace/tracer.h b/api/include/opentelemetry/trace/tracer.h
index 34230f1e25..8ea5359d13 100644
--- a/api/include/opentelemetry/trace/tracer.h
+++ b/api/include/opentelemetry/trace/tracer.h
@@ -24,9 +24,30 @@ class Tracer
    * Starts a span.
    */
   virtual nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes = {},
+					    const KeyValueIterable &attributes,
                                             const StartSpanOptions &options = {}) noexcept = 0;
 
+  nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
+                                            const StartSpanOptions &options = {}) noexcept {
+      return this->StartSpan(name, {}, options);
+  }
+
+  template <class T, nostd::enable_if_t<detail::is_key_value_iterable<T>::value> * = nullptr>
+  nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
+	  const T &attributes,
+                                            const StartSpanOptions &options = {}) noexcept {
+      return this->StartSpan(name, KeyValueIterableView<T>(attributes), options);
+  }
+
+  nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
+                std::initializer_list<std::pair<nostd::string_view, common::AttributeValue>>
+                    attributes,
+                                            const StartSpanOptions &options = {}) noexcept {
+      return this->StartSpan(name, nostd::span<const std::pair<nostd::string_view, common::AttributeValue>>{
+                       attributes.begin(), attributes.end()},
+	      options);
+  }
+
   /**
    * Force any buffered spans to flush.
    * @param timeout to complete the flush
diff --git a/examples/plugin/load/main.cc b/examples/plugin/load/main.cc
index 3c6799fed0..71cb4626b3 100644
--- a/examples/plugin/load/main.cc
+++ b/examples/plugin/load/main.cc
@@ -1,4 +1,5 @@
 #include "opentelemetry/plugin/dynamic_load.h"
+#include "opentelemetry/trace/tracer.h"
 
 #include <cstring>
 #include <fstream>
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index 2230f60d72..51b2d85290 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -14,7 +14,7 @@ class Span final : public trace::Span
 public:
   Span(std::shared_ptr<Tracer> &&tracer,
        nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> /* attributes */,
+					    const opentelemetry::trace::KeyValueIterable& /*attributes*/,
        const trace::StartSpanOptions & /*options*/) noexcept
       : tracer_{std::move(tracer)}, name_{name}
   {
@@ -59,7 +59,7 @@ class Span final : public trace::Span
 Tracer::Tracer(nostd::string_view /*output*/) {}
 
 nostd::unique_ptr<trace::Span> Tracer::StartSpan(nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes,
+					    const opentelemetry::trace::KeyValueIterable &attributes,
                                                  const trace::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<opentelemetry::trace::Span>{
diff --git a/examples/plugin/plugin/tracer.h b/examples/plugin/plugin/tracer.h
index 07fdda9add..c396cb83c0 100644
--- a/examples/plugin/plugin/tracer.h
+++ b/examples/plugin/plugin/tracer.h
@@ -13,7 +13,7 @@ class Tracer final : public opentelemetry::trace::Tracer,
   // opentelemetry::trace::Tracer
   opentelemetry::nostd::unique_ptr<opentelemetry::trace::Span> StartSpan(
       opentelemetry::nostd::string_view name,
-					    opentelemetry::nostd::span<const opentelemetry::common::AttributeKeyValue> /* attributes */,
+					    const opentelemetry::trace::KeyValueIterable & /*attributes*/,
       const opentelemetry::trace::StartSpanOptions & /*options */) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t /*timeout*/) noexcept override {}
diff --git a/sdk/include/opentelemetry/sdk/trace/tracer.h b/sdk/include/opentelemetry/sdk/trace/tracer.h
index 10b44d9043..c32751d83c 100644
--- a/sdk/include/opentelemetry/sdk/trace/tracer.h
+++ b/sdk/include/opentelemetry/sdk/trace/tracer.h
@@ -37,7 +37,7 @@ class Tracer final : public trace_api::Tracer, public std::enable_shared_from_th
 
   nostd::unique_ptr<trace_api::Span> StartSpan(
       nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes = {},
+					    const trace_api::KeyValueIterable &attributes,
       const trace_api::StartSpanOptions &options = {}) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t timeout) noexcept override;
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 05fe42b6de..630d77b89d 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -41,7 +41,7 @@ SteadyTimestamp NowOr(const SteadyTimestamp &steady)
 Span::Span(std::shared_ptr<Tracer> &&tracer,
            std::shared_ptr<SpanProcessor> processor,
            nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes,
+					    const trace_api::KeyValueIterable &attributes,
            const trace_api::StartSpanOptions &options) noexcept
     : tracer_{std::move(tracer)},
       processor_{processor},
@@ -56,10 +56,10 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
   processor_->OnStart(*recordable_);
   recordable_->SetName(name);
 
-  for (auto &attr : attributes)
-  {
-    recordable_->SetAttribute(attr.key, std::move(attr.value));
-  }
+  attributes.ForEachKeyValue([&](nostd::string_view key, common::AttributeValue value) noexcept {
+    recordable_->SetAttribute(key, std::move(value));
+    return true;
+    });
 
   recordable_->SetStartTime(NowOr(options.start_system_time));
   start_steady_time = NowOr(options.start_steady_time);
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index e7ff256604..0470b799d0 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -18,7 +18,7 @@ class Span final : public trace_api::Span
   explicit Span(std::shared_ptr<Tracer> &&tracer,
                 std::shared_ptr<SpanProcessor> processor,
                 nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes,
+					    const trace_api::KeyValueIterable &attributes,
                 const trace_api::StartSpanOptions &options) noexcept;
 
   ~Span() override;
diff --git a/sdk/src/trace/tracer.cc b/sdk/src/trace/tracer.cc
index fb4673f912..b83fb345b1 100644
--- a/sdk/src/trace/tracer.cc
+++ b/sdk/src/trace/tracer.cc
@@ -21,7 +21,7 @@ std::shared_ptr<SpanProcessor> Tracer::GetProcessor() const noexcept
 
 nostd::unique_ptr<trace_api::Span> Tracer::StartSpan(
     nostd::string_view name,
-					    nostd::span<const common::AttributeKeyValue> attributes,
+					    const trace_api::KeyValueIterable &attributes,
     const trace_api::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<trace_api::Span>{
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index ec58671f12..4aa00d0726 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -48,12 +48,12 @@ class MockSpanExporter final : public SpanExporter
 
 namespace
 {
-std::shared_ptr<Tracer> initTracer(
+std::shared_ptr<opentelemetry::trace::Tracer> initTracer(
     std::shared_ptr<std::vector<std::unique_ptr<SpanData>>> &received)
 {
   std::unique_ptr<SpanExporter> exporter(new MockSpanExporter(received));
   std::shared_ptr<SimpleSpanProcessor> processor(new SimpleSpanProcessor(std::move(exporter)));
-  return std::shared_ptr<Tracer>(new Tracer(processor));
+  return std::shared_ptr<opentelemetry::trace::Tracer>(new Tracer(processor));
 }
 }  // namespace
 
@@ -114,7 +114,7 @@ TEST(Tracer, StartSpanWithOptionsTime)
   ASSERT_EQ(std::chrono::nanoseconds(30), span_data->GetDuration());
 }
 
-TEST(Tracer, StartSpanWithOptionsAttributes)
+TEST(Tracer, StartSpanWithAttributes)
 {
   std::shared_ptr<std::vector<std::unique_ptr<SpanData>>> spans_received(
       new std::vector<std::unique_ptr<SpanData>>);
@@ -122,14 +122,30 @@ TEST(Tracer, StartSpanWithOptionsAttributes)
 
 
   {
-      common::AttributeKeyValue attrs[] = {{"attr1", 314159}, {"attr2", false}, {"attr1", "string"}};
-      tracer->StartSpan("span 1", attrs);
+      tracer->StartSpan("span 1", {{"attr1", 314159}, {"attr2", false}, {"attr1", "string"}});
+
+      std::map<std::string, common::AttributeValue> m;
+      m["attr3"] = 3.0;
+      tracer->StartSpan("span 2", m);
+
+      char* local_value = new char[6];
+      local_value[0] = '\0';
+      tracer->StartSpan("span 3", {{"attr4", local_value}});
+      delete local_value;
   }
 
-  ASSERT_EQ(1, spans_received->size());
+  ASSERT_EQ(3, spans_received->size());
 
   auto &span_data = spans_received->at(0);
   ASSERT_EQ(2, span_data->GetAttributes().size());
   ASSERT_EQ("string", nostd::get<nostd::string_view>(span_data->GetAttributes().at("attr1")));
   ASSERT_EQ(false, nostd::get<bool>(span_data->GetAttributes().at("attr2")));
+
+  auto &span_data2 = spans_received->at(1);
+  ASSERT_EQ(1, span_data2->GetAttributes().size());
+  ASSERT_EQ(3.0, nostd::get<double>(span_data2->GetAttributes().at("attr3")));
+
+  auto &span_data3 = spans_received->at(2);
+  ASSERT_EQ(1, span_data2->GetAttributes().size());
+  ASSERT_EQ("", nostd::get<nostd::string_view>(span_data2->GetAttributes().at("attr4")));
 }

From d0a25f2c86dd487e5569cbf32d1b9d2270a5b20e Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Mon, 22 Jun 2020 08:55:49 -0700
Subject: [PATCH 15/18] Format

---
 api/include/opentelemetry/plugin/factory.h   |  7 +++--
 api/include/opentelemetry/trace/noop.h       |  2 +-
 api/include/opentelemetry/trace/span.h       |  3 +-
 api/include/opentelemetry/trace/tracer.h     | 30 +++++++++++---------
 examples/plugin/plugin/tracer.cc             |  9 +++---
 examples/plugin/plugin/tracer.h              |  2 +-
 sdk/include/opentelemetry/sdk/trace/tracer.h |  2 +-
 sdk/src/trace/span.cc                        |  4 +--
 sdk/src/trace/span.h                         |  2 +-
 sdk/src/trace/tracer.cc                      |  6 ++--
 sdk/test/trace/tracer_test.cc                | 17 ++++++-----
 11 files changed, 45 insertions(+), 39 deletions(-)

diff --git a/api/include/opentelemetry/plugin/factory.h b/api/include/opentelemetry/plugin/factory.h
index 60e8f5ab3b..abec73867a 100644
--- a/api/include/opentelemetry/plugin/factory.h
+++ b/api/include/opentelemetry/plugin/factory.h
@@ -37,7 +37,8 @@ class Factory final
    * @return a Tracer on success or nullptr on failure.
    */
   std::shared_ptr<opentelemetry::trace::Tracer> MakeTracer(nostd::string_view tracer_config,
-                                     std::string &error_message) const noexcept
+                                                           std::string &error_message) const
+      noexcept
   {
     nostd::unique_ptr<char[]> plugin_error_message;
     auto tracer_handle = factory_impl_->MakeTracerHandle(tracer_config, plugin_error_message);
@@ -46,8 +47,8 @@ class Factory final
       detail::CopyErrorMessage(plugin_error_message.get(), error_message);
       return nullptr;
     }
-    return std::shared_ptr<opentelemetry::trace::Tracer>{new (std::nothrow)
-                                       Tracer{library_handle_, std::move(tracer_handle)}};
+    return std::shared_ptr<opentelemetry::trace::Tracer>{
+        new (std::nothrow) Tracer{library_handle_, std::move(tracer_handle)}};
   }
 
 private:
diff --git a/api/include/opentelemetry/trace/noop.h b/api/include/opentelemetry/trace/noop.h
index 423f40dca5..fbb0e0cb68 100644
--- a/api/include/opentelemetry/trace/noop.h
+++ b/api/include/opentelemetry/trace/noop.h
@@ -60,7 +60,7 @@ class NoopTracer final : public Tracer, public std::enable_shared_from_this<Noop
 public:
   // Tracer
   nostd::unique_ptr<Span> StartSpan(nostd::string_view /*name*/,
-					    const KeyValueIterable & /*attributes*/,
+                                    const KeyValueIterable & /*attributes*/,
                                     const StartSpanOptions & /*options*/) noexcept override
   {
     return nostd::unique_ptr<Span>{new (std::nothrow) NoopSpan{this->shared_from_this()}};
diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index e6540cd43e..12b7bf5230 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -81,7 +81,8 @@ class Span
 
   // Sets an attribute on the Span. If the Span previously contained a mapping for
   // the key, the old value is replaced.
-  virtual void SetAttribute(nostd::string_view key, const common::AttributeValue &&value) noexcept = 0;
+  virtual void SetAttribute(nostd::string_view key,
+                            const common::AttributeValue &&value) noexcept = 0;
 
   // Adds an event to the Span.
   virtual void AddEvent(nostd::string_view name) noexcept = 0;
diff --git a/api/include/opentelemetry/trace/tracer.h b/api/include/opentelemetry/trace/tracer.h
index 8ea5359d13..f488b8e613 100644
--- a/api/include/opentelemetry/trace/tracer.h
+++ b/api/include/opentelemetry/trace/tracer.h
@@ -24,28 +24,32 @@ class Tracer
    * Starts a span.
    */
   virtual nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
-					    const KeyValueIterable &attributes,
+                                            const KeyValueIterable &attributes,
                                             const StartSpanOptions &options = {}) noexcept = 0;
 
   nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
-                                            const StartSpanOptions &options = {}) noexcept {
-      return this->StartSpan(name, {}, options);
+                                    const StartSpanOptions &options = {}) noexcept
+  {
+    return this->StartSpan(name, {}, options);
   }
 
   template <class T, nostd::enable_if_t<detail::is_key_value_iterable<T>::value> * = nullptr>
   nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
-	  const T &attributes,
-                                            const StartSpanOptions &options = {}) noexcept {
-      return this->StartSpan(name, KeyValueIterableView<T>(attributes), options);
+                                    const T &attributes,
+                                    const StartSpanOptions &options = {}) noexcept
+  {
+    return this->StartSpan(name, KeyValueIterableView<T>(attributes), options);
   }
 
-  nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
-                std::initializer_list<std::pair<nostd::string_view, common::AttributeValue>>
-                    attributes,
-                                            const StartSpanOptions &options = {}) noexcept {
-      return this->StartSpan(name, nostd::span<const std::pair<nostd::string_view, common::AttributeValue>>{
-                       attributes.begin(), attributes.end()},
-	      options);
+  nostd::unique_ptr<Span> StartSpan(
+      nostd::string_view name,
+      std::initializer_list<std::pair<nostd::string_view, common::AttributeValue>> attributes,
+      const StartSpanOptions &options = {}) noexcept
+  {
+    return this->StartSpan(name,
+                           nostd::span<const std::pair<nostd::string_view, common::AttributeValue>>{
+                               attributes.begin(), attributes.end()},
+                           options);
   }
 
   /**
diff --git a/examples/plugin/plugin/tracer.cc b/examples/plugin/plugin/tracer.cc
index 51b2d85290..3aa68e8b15 100644
--- a/examples/plugin/plugin/tracer.cc
+++ b/examples/plugin/plugin/tracer.cc
@@ -14,7 +14,7 @@ class Span final : public trace::Span
 public:
   Span(std::shared_ptr<Tracer> &&tracer,
        nostd::string_view name,
-					    const opentelemetry::trace::KeyValueIterable& /*attributes*/,
+       const opentelemetry::trace::KeyValueIterable & /*attributes*/,
        const trace::StartSpanOptions & /*options*/) noexcept
       : tracer_{std::move(tracer)}, name_{name}
   {
@@ -58,9 +58,10 @@ class Span final : public trace::Span
 
 Tracer::Tracer(nostd::string_view /*output*/) {}
 
-nostd::unique_ptr<trace::Span> Tracer::StartSpan(nostd::string_view name,
-					    const opentelemetry::trace::KeyValueIterable &attributes,
-                                                 const trace::StartSpanOptions &options) noexcept
+nostd::unique_ptr<trace::Span> Tracer::StartSpan(
+    nostd::string_view name,
+    const opentelemetry::trace::KeyValueIterable &attributes,
+    const trace::StartSpanOptions &options) noexcept
 {
   return nostd::unique_ptr<opentelemetry::trace::Span>{
       new (std::nothrow) Span{this->shared_from_this(), name, attributes, options}};
diff --git a/examples/plugin/plugin/tracer.h b/examples/plugin/plugin/tracer.h
index c396cb83c0..ad1b98633d 100644
--- a/examples/plugin/plugin/tracer.h
+++ b/examples/plugin/plugin/tracer.h
@@ -13,7 +13,7 @@ class Tracer final : public opentelemetry::trace::Tracer,
   // opentelemetry::trace::Tracer
   opentelemetry::nostd::unique_ptr<opentelemetry::trace::Span> StartSpan(
       opentelemetry::nostd::string_view name,
-					    const opentelemetry::trace::KeyValueIterable & /*attributes*/,
+      const opentelemetry::trace::KeyValueIterable & /*attributes*/,
       const opentelemetry::trace::StartSpanOptions & /*options */) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t /*timeout*/) noexcept override {}
diff --git a/sdk/include/opentelemetry/sdk/trace/tracer.h b/sdk/include/opentelemetry/sdk/trace/tracer.h
index c32751d83c..577785878a 100644
--- a/sdk/include/opentelemetry/sdk/trace/tracer.h
+++ b/sdk/include/opentelemetry/sdk/trace/tracer.h
@@ -37,7 +37,7 @@ class Tracer final : public trace_api::Tracer, public std::enable_shared_from_th
 
   nostd::unique_ptr<trace_api::Span> StartSpan(
       nostd::string_view name,
-					    const trace_api::KeyValueIterable &attributes,
+      const trace_api::KeyValueIterable &attributes,
       const trace_api::StartSpanOptions &options = {}) noexcept override;
 
   void ForceFlushWithMicroseconds(uint64_t timeout) noexcept override;
diff --git a/sdk/src/trace/span.cc b/sdk/src/trace/span.cc
index 630d77b89d..dde8710ec2 100644
--- a/sdk/src/trace/span.cc
+++ b/sdk/src/trace/span.cc
@@ -41,7 +41,7 @@ SteadyTimestamp NowOr(const SteadyTimestamp &steady)
 Span::Span(std::shared_ptr<Tracer> &&tracer,
            std::shared_ptr<SpanProcessor> processor,
            nostd::string_view name,
-					    const trace_api::KeyValueIterable &attributes,
+           const trace_api::KeyValueIterable &attributes,
            const trace_api::StartSpanOptions &options) noexcept
     : tracer_{std::move(tracer)},
       processor_{processor},
@@ -59,7 +59,7 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
   attributes.ForEachKeyValue([&](nostd::string_view key, common::AttributeValue value) noexcept {
     recordable_->SetAttribute(key, std::move(value));
     return true;
-    });
+  });
 
   recordable_->SetStartTime(NowOr(options.start_system_time));
   start_steady_time = NowOr(options.start_steady_time);
diff --git a/sdk/src/trace/span.h b/sdk/src/trace/span.h
index 0470b799d0..db8d01ab4e 100644
--- a/sdk/src/trace/span.h
+++ b/sdk/src/trace/span.h
@@ -18,7 +18,7 @@ class Span final : public trace_api::Span
   explicit Span(std::shared_ptr<Tracer> &&tracer,
                 std::shared_ptr<SpanProcessor> processor,
                 nostd::string_view name,
-					    const trace_api::KeyValueIterable &attributes,
+                const trace_api::KeyValueIterable &attributes,
                 const trace_api::StartSpanOptions &options) noexcept;
 
   ~Span() override;
diff --git a/sdk/src/trace/tracer.cc b/sdk/src/trace/tracer.cc
index b83fb345b1..311459060b 100644
--- a/sdk/src/trace/tracer.cc
+++ b/sdk/src/trace/tracer.cc
@@ -21,11 +21,11 @@ std::shared_ptr<SpanProcessor> Tracer::GetProcessor() const noexcept
 
 nostd::unique_ptr<trace_api::Span> Tracer::StartSpan(
     nostd::string_view name,
-					    const trace_api::KeyValueIterable &attributes,
+    const trace_api::KeyValueIterable &attributes,
     const trace_api::StartSpanOptions &options) noexcept
 {
-  return nostd::unique_ptr<trace_api::Span>{
-      new (std::nothrow) Span{this->shared_from_this(), processor_.load(), name, attributes, options}};
+  return nostd::unique_ptr<trace_api::Span>{new (std::nothrow) Span{
+      this->shared_from_this(), processor_.load(), name, attributes, options}};
 }
 
 void Tracer::ForceFlushWithMicroseconds(uint64_t timeout) noexcept
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index 4aa00d0726..b254dcf2e7 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -120,18 +120,17 @@ TEST(Tracer, StartSpanWithAttributes)
       new std::vector<std::unique_ptr<SpanData>>);
   auto tracer = initTracer(spans_received);
 
-
   {
-      tracer->StartSpan("span 1", {{"attr1", 314159}, {"attr2", false}, {"attr1", "string"}});
+    tracer->StartSpan("span 1", {{"attr1", 314159}, {"attr2", false}, {"attr1", "string"}});
 
-      std::map<std::string, common::AttributeValue> m;
-      m["attr3"] = 3.0;
-      tracer->StartSpan("span 2", m);
+    std::map<std::string, common::AttributeValue> m;
+    m["attr3"] = 3.0;
+    tracer->StartSpan("span 2", m);
 
-      char* local_value = new char[6];
-      local_value[0] = '\0';
-      tracer->StartSpan("span 3", {{"attr4", local_value}});
-      delete local_value;
+    char *local_value = new char[6];
+    local_value[0]    = '\0';
+    tracer->StartSpan("span 3", {{"attr4", local_value}});
+    delete local_value;
   }
 
   ASSERT_EQ(3, spans_received->size());

From 21ef99fdfa3e76547dc74d4b28ac7a4d293bebd8 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Mon, 22 Jun 2020 09:37:46 -0700
Subject: [PATCH 16/18] Format

---
 api/include/opentelemetry/trace/span.h   |  5 -----
 api/include/opentelemetry/trace/tracer.h |  5 +++++
 sdk/test/trace/tracer_test.cc            | 11 +----------
 3 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/api/include/opentelemetry/trace/span.h b/api/include/opentelemetry/trace/span.h
index 12b7bf5230..77265387e6 100644
--- a/api/include/opentelemetry/trace/span.h
+++ b/api/include/opentelemetry/trace/span.h
@@ -37,11 +37,6 @@ struct StartSpanOptions
   core::SystemTimestamp start_system_time;
   core::SteadyTimestamp start_steady_time;
 
-  // Optionally set 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.
-
   // TODO:
   // Span(Context?) parent;
   // SpanContext remote_parent;
diff --git a/api/include/opentelemetry/trace/tracer.h b/api/include/opentelemetry/trace/tracer.h
index f488b8e613..825ff39fb1 100644
--- a/api/include/opentelemetry/trace/tracer.h
+++ b/api/include/opentelemetry/trace/tracer.h
@@ -22,6 +22,11 @@ class Tracer
   virtual ~Tracer() = 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.
    */
   virtual nostd::unique_ptr<Span> StartSpan(nostd::string_view name,
                                             const KeyValueIterable &attributes,
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index b254dcf2e7..366c6428a1 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -126,14 +126,9 @@ TEST(Tracer, StartSpanWithAttributes)
     std::map<std::string, common::AttributeValue> m;
     m["attr3"] = 3.0;
     tracer->StartSpan("span 2", m);
-
-    char *local_value = new char[6];
-    local_value[0]    = '\0';
-    tracer->StartSpan("span 3", {{"attr4", local_value}});
-    delete local_value;
   }
 
-  ASSERT_EQ(3, spans_received->size());
+  ASSERT_EQ(2, spans_received->size());
 
   auto &span_data = spans_received->at(0);
   ASSERT_EQ(2, span_data->GetAttributes().size());
@@ -143,8 +138,4 @@ TEST(Tracer, StartSpanWithAttributes)
   auto &span_data2 = spans_received->at(1);
   ASSERT_EQ(1, span_data2->GetAttributes().size());
   ASSERT_EQ(3.0, nostd::get<double>(span_data2->GetAttributes().at("attr3")));
-
-  auto &span_data3 = spans_received->at(2);
-  ASSERT_EQ(1, span_data2->GetAttributes().size());
-  ASSERT_EQ("", nostd::get<nostd::string_view>(span_data2->GetAttributes().at("attr4")));
 }

From dd8e1b0f29a459eb618cd19862b08386b01a4ae8 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Mon, 22 Jun 2020 10:00:59 -0700
Subject: [PATCH 17/18] Format

---
 examples/plugin/load/main.cc  | 1 -
 sdk/test/trace/tracer_test.cc | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/examples/plugin/load/main.cc b/examples/plugin/load/main.cc
index 71cb4626b3..3c6799fed0 100644
--- a/examples/plugin/load/main.cc
+++ b/examples/plugin/load/main.cc
@@ -1,5 +1,4 @@
 #include "opentelemetry/plugin/dynamic_load.h"
-#include "opentelemetry/trace/tracer.h"
 
 #include <cstring>
 #include <fstream>
diff --git a/sdk/test/trace/tracer_test.cc b/sdk/test/trace/tracer_test.cc
index 366c6428a1..056227aa8d 100644
--- a/sdk/test/trace/tracer_test.cc
+++ b/sdk/test/trace/tracer_test.cc
@@ -105,7 +105,7 @@ TEST(Tracer, StartSpanWithOptionsTime)
   opentelemetry::trace::EndSpanOptions end;
   end.end_steady_time = SteadyTimestamp(std::chrono::nanoseconds(40));
 
-  tracer->StartSpan("span 1", {}, start)->End(end);
+  tracer->StartSpan("span 1", start)->End(end);
 
   ASSERT_EQ(1, spans_received->size());
 

From 8723b37f923dda9d01d7ed6d0c5d11b7224aa8f5 Mon Sep 17 00:00:00 2001
From: Johannes Tax <jtax@newrelic.com>
Date: Mon, 22 Jun 2020 10:10:19 -0700
Subject: [PATCH 18/18] Remove unused struct

---
 api/include/opentelemetry/common/attribute_value.h | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/api/include/opentelemetry/common/attribute_value.h b/api/include/opentelemetry/common/attribute_value.h
index 8a6b0c1b39..6340a4f97c 100644
--- a/api/include/opentelemetry/common/attribute_value.h
+++ b/api/include/opentelemetry/common/attribute_value.h
@@ -24,14 +24,5 @@ using AttributeValue = nostd::variant<bool,
                                       nostd::span<const uint64_t>,
                                       nostd::span<const double>,
                                       nostd::span<const nostd::string_view>>;
-
-/**
- * A key/value pair that can be used to set attributes.
- */
-struct AttributeKeyValue
-{
-  nostd::string_view key;
-  AttributeValue value;
-};
 }  // namespace common
 OPENTELEMETRY_END_NAMESPACE