From 7f8e005c34d9f053ab250569d91f39947681ead8 Mon Sep 17 00:00:00 2001
From: Munir Abdinur <munir_abdinur@hotmail.com>
Date: Wed, 20 Mar 2024 14:47:06 -0400
Subject: [PATCH 1/6] feat: add span links to Datadog API

---
 lib/datadog/tracing/span.rb                   |   9 +-
 lib/datadog/tracing/span_link.rb              |  80 +++++++++++
 lib/datadog/tracing/trace_digest.rb           |   2 +-
 .../tracing/transport/serializable_trace.rb   |   4 +-
 sig/datadog/tracing/span_link.rbs             | 133 ++++++++++++++++++
 spec/datadog/tracing/span_link_spec.rb        | 106 ++++++++++++++
 spec/datadog/tracing/span_spec.rb             |   1 +
 .../transport/serializable_trace_spec.rb      |  38 +++++
 8 files changed, 369 insertions(+), 4 deletions(-)
 create mode 100644 lib/datadog/tracing/span_link.rb
 create mode 100644 sig/datadog/tracing/span_link.rbs
 create mode 100644 spec/datadog/tracing/span_link_spec.rb

diff --git a/lib/datadog/tracing/span.rb b/lib/datadog/tracing/span.rb
index 018b50e6690..187d25c31e1 100644
--- a/lib/datadog/tracing/span.rb
+++ b/lib/datadog/tracing/span.rb
@@ -26,6 +26,7 @@ class Span
         :parent_id,
         :resource,
         :service,
+        :links,
         :type,
         :start_time,
         :status,
@@ -58,7 +59,8 @@ def initialize(
         status: 0,
         type: nil,
         trace_id: nil,
-        service_entry: nil
+        service_entry: nil,
+        links: nil
       )
         @name = Core::Utils::SafeDup.frozen_or_dup(name)
         @service = Core::Utils::SafeDup.frozen_or_dup(service)
@@ -86,6 +88,8 @@ def initialize(
 
         @service_entry = service_entry
 
+        @links = links || []
+
         # Mark with the service entry span metric, if applicable
         set_metric(Metadata::Ext::TAG_TOP_LEVEL, 1.0) if service_entry
       end
@@ -136,7 +140,8 @@ def to_hash
           service: @service,
           span_id: @id,
           trace_id: @trace_id,
-          type: @type
+          type: @type,
+          span_links: @links.map!(&:to_hash)
         }
 
         if stopped?
diff --git a/lib/datadog/tracing/span_link.rb b/lib/datadog/tracing/span_link.rb
new file mode 100644
index 00000000000..e88c52e480f
--- /dev/null
+++ b/lib/datadog/tracing/span_link.rb
@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+module Datadog
+  module Tracing
+    # SpanLink represents a causal link between two spans.
+    # @public_api
+    class SpanLink
+      # @!attribute [r] span_id
+      #   Datadog id for the currently active span.
+      #   @return [Integer]
+      # @!attribute [r] trace_id
+      #   Datadog id for the currently active trace.
+      #   @return [Integer]
+      # @!attribute [r] attributes
+      #   Datadog-specific tags that support richer distributed tracing association.
+      #   @return [Hash<String,String>]
+      # @!attribute [r] trace_flags
+      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
+      #   @return [Integer]
+      #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      # @!attribute [r] trace_state
+      #   The W3C "tracestate" extracted from a distributed context.
+      #   This field is a string representing vendor-specific distribution data.
+      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
+      #   on every propagation injection.
+      #   @return [String]
+      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
+      attr_reader \
+        :span_id,
+        :trace_id,
+        :attributes,
+        :trace_flags,
+        :trace_state
+
+      def initialize(
+        span_id: nil,
+        trace_id: nil,
+        attributes: nil,
+        trace_flags: nil,
+        trace_state: nil
+      )
+        @span_id = span_id
+        @trace_id = trace_id
+        @attributes = attributes && attributes.dup.freeze
+        @trace_flags = trace_flags
+        @trace_state = trace_state && trace_state.dup.freeze
+        @dropped_attributes = 0
+        freeze
+      end
+
+      def to_hash
+        h = {
+          span_id: @span_id,
+          trace_id: Tracing::Utils::TraceId.to_low_order(@trace_id),
+
+        }
+        if @trace_id.to_i > Tracing::Utils::EXTERNAL_MAX_ID
+          h[:trace_id_high] =
+            Tracing::Utils::TraceId.to_high_order(@trace_id)
+        end
+        if @attributes
+          h[:attributes] = {}
+          @attributes.each do |k1, v1|
+            h[:attributes][k1.to_s] = v1.to_s
+          end
+        end
+        h[:dropped_attributes_count] = @dropped_attributes if @dropped_attributes > 0
+        h[:tracestate] = @trace_state if @trace_state
+        # If traceflags set, the high bit (bit 31) should be set to 1 (uint32).
+        # This helps us distinguish between when the sample decision is zero or not set
+        h[:flags] = if @trace_flags
+                      @trace_flags | (1 << 31)
+                    else
+                      0
+                    end
+        h
+      end
+    end
+  end
+end
diff --git a/lib/datadog/tracing/trace_digest.rb b/lib/datadog/tracing/trace_digest.rb
index 751bfa61d9e..790013e56e6 100644
--- a/lib/datadog/tracing/trace_digest.rb
+++ b/lib/datadog/tracing/trace_digest.rb
@@ -4,7 +4,7 @@ module Datadog
   module Tracing
     # Trace digest that represents the important parts of an active trace.
     # Used to propagate context and continue traces across execution boundaries.
-    # TODO: Update all references from span to parent (ex: span_id -> parent_id) 
+    # TODO: Update all references from span to parent (ex: span_id -> parent_id)
     # @public_api
     class TraceDigest
       # @!attribute [r] span_id
diff --git a/lib/datadog/tracing/transport/serializable_trace.rb b/lib/datadog/tracing/transport/serializable_trace.rb
index e14ce2c7b27..44cfb696280 100644
--- a/lib/datadog/tracing/transport/serializable_trace.rb
+++ b/lib/datadog/tracing/transport/serializable_trace.rb
@@ -58,7 +58,7 @@ def initialize(span)
         def to_msgpack(packer = nil)
           packer ||= MessagePack::Packer.new
 
-          number_of_elements_to_write = 10
+          number_of_elements_to_write = 11
 
           if span.stopped?
             packer.write_map_header(number_of_elements_to_write + 2) # Set header with how many elements in the map
@@ -93,6 +93,8 @@ def to_msgpack(packer = nil)
           packer.write(span.meta)
           packer.write('metrics')
           packer.write(span.metrics)
+          packer.write('span_links')
+          packer.write(span.links.map!(&:to_hash))
           packer.write('error')
           packer.write(span.status)
           packer
diff --git a/sig/datadog/tracing/span_link.rbs b/sig/datadog/tracing/span_link.rbs
new file mode 100644
index 00000000000..558a561acfb
--- /dev/null
+++ b/sig/datadog/tracing/span_link.rbs
@@ -0,0 +1,133 @@
+module Datadog
+  module Tracing
+    # SpanLink represents a causal link between two spans.
+    # @public_api
+    class SpanLink
+      @span_id: untyped
+
+      @trace_id: untyped
+
+      @attributes: untyped
+
+      @trace_flags: untyped
+
+      @trace_state: untyped
+
+      @dropped_attributes: untyped
+
+      # @!attribute [r] span_id
+      #   Datadog id for the currently active span.
+      #   @return [Integer]
+      # @!attribute [r] trace_id
+      #   Datadog id for the currently active trace.
+      #   @return [Integer]
+      # @!attribute [r] attributes
+      #   Datadog-specific tags that support richer distributed tracing association.
+      #   @return [Hash<String,String>]
+      # @!attribute [r] trace_flags
+      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
+      #   @return [Integer]
+      #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      # @!attribute [r] trace_state
+      #   The W3C "tracestate" extracted from a distributed context.
+      #   This field is a string representing vendor-specific distribution data.
+      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
+      #   on every propagation injection.
+      #   @return [String]
+      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
+      attr_reader span_id: untyped
+
+      # @!attribute [r] span_id
+      #   Datadog id for the currently active span.
+      #   @return [Integer]
+      # @!attribute [r] trace_id
+      #   Datadog id for the currently active trace.
+      #   @return [Integer]
+      # @!attribute [r] attributes
+      #   Datadog-specific tags that support richer distributed tracing association.
+      #   @return [Hash<String,String>]
+      # @!attribute [r] trace_flags
+      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
+      #   @return [Integer]
+      #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      # @!attribute [r] trace_state
+      #   The W3C "tracestate" extracted from a distributed context.
+      #   This field is a string representing vendor-specific distribution data.
+      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
+      #   on every propagation injection.
+      #   @return [String]
+      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
+      attr_reader trace_id: untyped
+
+      # @!attribute [r] span_id
+      #   Datadog id for the currently active span.
+      #   @return [Integer]
+      # @!attribute [r] trace_id
+      #   Datadog id for the currently active trace.
+      #   @return [Integer]
+      # @!attribute [r] attributes
+      #   Datadog-specific tags that support richer distributed tracing association.
+      #   @return [Hash<String,String>]
+      # @!attribute [r] trace_flags
+      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
+      #   @return [Integer]
+      #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      # @!attribute [r] trace_state
+      #   The W3C "tracestate" extracted from a distributed context.
+      #   This field is a string representing vendor-specific distribution data.
+      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
+      #   on every propagation injection.
+      #   @return [String]
+      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
+      attr_reader attributes: untyped
+
+      # @!attribute [r] span_id
+      #   Datadog id for the currently active span.
+      #   @return [Integer]
+      # @!attribute [r] trace_id
+      #   Datadog id for the currently active trace.
+      #   @return [Integer]
+      # @!attribute [r] attributes
+      #   Datadog-specific tags that support richer distributed tracing association.
+      #   @return [Hash<String,String>]
+      # @!attribute [r] trace_flags
+      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
+      #   @return [Integer]
+      #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      # @!attribute [r] trace_state
+      #   The W3C "tracestate" extracted from a distributed context.
+      #   This field is a string representing vendor-specific distribution data.
+      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
+      #   on every propagation injection.
+      #   @return [String]
+      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
+      attr_reader trace_flags: untyped
+
+      # @!attribute [r] span_id
+      #   Datadog id for the currently active span.
+      #   @return [Integer]
+      # @!attribute [r] trace_id
+      #   Datadog id for the currently active trace.
+      #   @return [Integer]
+      # @!attribute [r] attributes
+      #   Datadog-specific tags that support richer distributed tracing association.
+      #   @return [Hash<String,String>]
+      # @!attribute [r] trace_flags
+      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
+      #   @return [Integer]
+      #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      # @!attribute [r] trace_state
+      #   The W3C "tracestate" extracted from a distributed context.
+      #   This field is a string representing vendor-specific distribution data.
+      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
+      #   on every propagation injection.
+      #   @return [String]
+      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
+      attr_reader trace_state: untyped
+
+      def initialize: (?span_id: untyped?, ?trace_id: untyped?, ?attributes: untyped?, ?trace_flags: untyped?, ?trace_state: untyped?) -> void
+
+      def to_hash: () -> untyped
+    end
+  end
+end
\ No newline at end of file
diff --git a/spec/datadog/tracing/span_link_spec.rb b/spec/datadog/tracing/span_link_spec.rb
new file mode 100644
index 00000000000..f840ef52819
--- /dev/null
+++ b/spec/datadog/tracing/span_link_spec.rb
@@ -0,0 +1,106 @@
+require 'spec_helper'
+require 'support/object_helpers'
+
+require 'datadog/tracing/span_link'
+
+RSpec.describe Datadog::Tracing::SpanLink do
+  subject(:span_link) { described_class.new(**options) }
+  let(:options) { {} }
+
+  describe '::new' do
+    context 'by default' do
+      it do
+        is_expected.to have_attributes(
+          span_id: nil,
+          attributes: nil,
+          trace_id: nil,
+          trace_flags: nil,
+          trace_state: nil,
+        )
+      end
+
+      it { is_expected.to be_frozen }
+    end
+
+    context 'given' do
+      context ':span_id' do
+        let(:options) { { span_id: span_id } }
+        let(:span_id) { Datadog::Tracing::Utils.next_id }
+
+        it { is_expected.to have_attributes(span_id: span_id) }
+      end
+
+      context ':attributes' do
+        let(:options) { { attributes: attributes } }
+        let(:attributes) { { tag: 'value' } }
+
+        it { is_expected.to have_attributes(attributes: be_a_frozen_copy_of(attributes)) }
+      end
+
+      context ':trace_id' do
+        let(:options) { { trace_id: trace_id } }
+        let(:trace_id) { Datadog::Tracing::Utils::TraceId.next_id }
+
+        it { is_expected.to have_attributes(trace_id: trace_id) }
+      end
+
+      context ':trace_flags' do
+        let(:options) { { trace_flags: trace_flags } }
+        let(:trace_flags) { 0x01 }
+
+        it { is_expected.to have_attributes(trace_flags: 0x01) }
+      end
+
+      context ':trace_state' do
+        let(:options) { { trace_state: trace_state } }
+        let(:trace_state) { 'vendor1=value,v2=v' }
+
+        it { is_expected.to have_attributes(trace_state: be_a_frozen_copy_of('vendor1=value,v2=v')) }
+      end
+    end
+  end
+
+  describe '#to_hash' do
+    subject(:to_hash) { span_link.to_hash }
+
+    context 'with required fields' do
+      let(:options) { { span_id: 34, trace_id: 12 } }
+
+      context 'when trace_id < 2^64' do
+        it { is_expected.to eq(trace_id: 12, span_id: 34, flags: 0) }
+      end
+
+      context 'when trace_id >= 2^64' do
+        let(:options) { { span_id: 34, trace_id: 2**64 + 12 } }
+        it { is_expected.to eq(trace_id: 12, trace_id_high: 1, span_id: 34, flags: 0) }
+      end
+    end
+
+    context 'with trace_state' do
+      let(:options) { { span_id: 34, trace_id: 12, trace_state: 'dd=s:1' } }
+      it { is_expected.to include(tracestate: 'dd=s:1') }
+    end
+
+    context 'with trace_flag' do
+      context 'when trace_flag is unset' do
+        let(:options) { { span_id: 34, trace_id: 12 } }
+        it { is_expected.to include(flags: 0) }
+      end
+
+      context 'when trace_flags is 0' do
+        let(:options) { { span_id: 34, trace_id: 12, trace_flags: 0 } }
+        it { is_expected.to include(flags: 2147483648) }
+      end
+
+      context 'when trace_flag is 1' do
+        let(:options) { { span_id: 34, trace_id: 12, trace_flags: 1 } }
+        it { is_expected.to include(flags: 2147483649) }
+      end
+    end
+
+    context 'with attributes' do
+      let(:options) { { span_id: 34, trace_id: 12, attributes: { 'link.name' => :test_link, 'link.id' => 1 } } }
+      it { is_expected.to include(attributes: { 'link.name' => 'test_link', 'link.id' => '1' }) }
+    end
+  end
+end
diff --git a/spec/datadog/tracing/span_spec.rb b/spec/datadog/tracing/span_spec.rb
index 22b33812dfb..0c6bca7f3f0 100644
--- a/spec/datadog/tracing/span_spec.rb
+++ b/spec/datadog/tracing/span_spec.rb
@@ -244,6 +244,7 @@
         type: nil,
         meta: {},
         metrics: {},
+        span_links: [],
         error: 0
       )
     end
diff --git a/spec/datadog/tracing/transport/serializable_trace_spec.rb b/spec/datadog/tracing/transport/serializable_trace_spec.rb
index 52136cfd932..4c961117e24 100644
--- a/spec/datadog/tracing/transport/serializable_trace_spec.rb
+++ b/spec/datadog/tracing/transport/serializable_trace_spec.rb
@@ -70,6 +70,44 @@
         end
       end
     end
+
+    context 'when given span links' do
+      subject(:unpacked_trace) { MessagePack.unpack(to_msgpack) }
+
+      let(:spans) do
+        Array.new(3) do |_i|
+          Datadog::Tracing::Span.new(
+            'dummy',
+            links: [Datadog::Tracing::SpanLink.new(
+              trace_id: 0xaaaaaaaaaaaaaaaaffffffffffffffff,
+              span_id: 0x1,
+              trace_state: 'vendor1=value,v2=v,dd=s:1',
+              trace_flags: 0x1,
+              attributes: { 'link.name' => 'test_link' }
+            )]
+          )
+        end
+      end
+
+      it 'serializes span links' do
+        expect(
+          unpacked_trace.map do |s|
+            s['span_links']
+          end
+        ).to all(
+          eq(
+            [{
+              'span_id' => 1,
+              'trace_id' => 0xffffffffffffffff,
+              'trace_id_high' => 0xaaaaaaaaaaaaaaaa,
+              'attributes' => { 'link.name' => 'test_link' },
+              'flags' => 2147483649,
+              'tracestate' => 'vendor1=value,v2=v,dd=s:1',
+            }]
+          )
+        )
+      end
+    end
   end
 
   describe '#to_json' do

From 6c26230ab8f7ccb212876e46deb4ae757dd3c852 Mon Sep 17 00:00:00 2001
From: Munir Abdinur <munir_abdinur@hotmail.com>
Date: Wed, 20 Mar 2024 16:05:14 -0400
Subject: [PATCH 2/6] flatten span link attributes

---
 .../opentelemetry/sdk/span_processor.rb       |  2 +-
 lib/datadog/opentelemetry/sdk/trace/span.rb   | 20 +++----------------
 lib/datadog/tracing/span_link.rb              |  4 +++-
 lib/datadog/tracing/utils.rb                  | 16 +++++++++++++++
 spec/datadog/tracing/span_link_spec.rb        | 12 +++++++++--
 5 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/lib/datadog/opentelemetry/sdk/span_processor.rb b/lib/datadog/opentelemetry/sdk/span_processor.rb
index 1860c3a193f..655facab164 100644
--- a/lib/datadog/opentelemetry/sdk/span_processor.rb
+++ b/lib/datadog/opentelemetry/sdk/span_processor.rb
@@ -115,7 +115,7 @@ def span_arguments(span, attributes)
 
           # DEV: There's no `flat_map!`; we have to split it into two operations
           attributes = attributes.map do |key, value|
-            Datadog::OpenTelemetry::Trace::Span.serialize_attribute(key, value)
+            Datadog::Tracing::Utils.serialize_attribute(key, value)
           end
           attributes.flatten!(1)
 
diff --git a/lib/datadog/opentelemetry/sdk/trace/span.rb b/lib/datadog/opentelemetry/sdk/trace/span.rb
index e6ccd7f964c..797809c36d2 100644
--- a/lib/datadog/opentelemetry/sdk/trace/span.rb
+++ b/lib/datadog/opentelemetry/sdk/trace/span.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require '../../../tracing/utils'
+
 module Datadog
   module OpenTelemetry
     module Trace
@@ -36,22 +38,6 @@ def status=(s)
           span.set_error(status.description) if status && status.code == ::OpenTelemetry::Trace::Status::ERROR
         end
 
-        # Serialize values into Datadog span tags and metrics.
-        # Notably, arrays are exploded into many keys, each with
-        # a numeric suffix representing the array index, for example:
-        # `'foo' => ['a','b']` becomes `'foo.0' => 'a', 'foo.1' => 'b'`
-        def self.serialize_attribute(key, value)
-          if value.is_a?(Array)
-            value.flat_map.with_index do |v, idx|
-              serialize_attribute("#{key}.#{idx}", v)
-            end
-          elsif value.is_a?(TrueClass) || value.is_a?(FalseClass)
-            [[key, value.to_s]]
-          else
-            [[key, value]]
-          end
-        end
-
         # Create a meaningful Datadog operation name from the OpenTelemetry
         # semantic convention for span kind and span attributes.
         # @see https://opentelemetry.io/docs/specs/semconv/general/trace/
@@ -123,7 +109,7 @@ def datadog_set_attribute(key)
               span.name = rich_name.downcase
             end
 
-            Span.serialize_attribute(key, @attributes[key]).each do |new_key, value|
+            Tracing::Utils.serialize_attribute(key, @attributes[key]).each do |new_key, value|
               override_datadog_values(span, new_key, value)
 
               # When an attribute is used to override a Datadog Span property,
diff --git a/lib/datadog/tracing/span_link.rb b/lib/datadog/tracing/span_link.rb
index e88c52e480f..1c85a00f533 100644
--- a/lib/datadog/tracing/span_link.rb
+++ b/lib/datadog/tracing/span_link.rb
@@ -61,7 +61,9 @@ def to_hash
         if @attributes
           h[:attributes] = {}
           @attributes.each do |k1, v1|
-            h[:attributes][k1.to_s] = v1.to_s
+            Tracing::Utils.serialize_attribute(k1, v1).each do |new_k1, value|
+              h[:attributes][new_k1.to_s] = value.to_s
+            end
           end
         end
         h[:dropped_attributes_count] = @dropped_attributes if @dropped_attributes > 0
diff --git a/lib/datadog/tracing/utils.rb b/lib/datadog/tracing/utils.rb
index 543b2986654..a0001f5679d 100644
--- a/lib/datadog/tracing/utils.rb
+++ b/lib/datadog/tracing/utils.rb
@@ -45,6 +45,22 @@ def self.reset!
         @id_rng = Random.new
       end
 
+      # Serialize values into Datadog span tags and metrics.
+      # Notably, arrays are exploded into many keys, each with
+      # a numeric suffix representing the array index, for example:
+      # `'foo' => ['a','b']` becomes `'foo.0' => 'a', 'foo.1' => 'b'`
+      def self.serialize_attribute(key, value)
+        if value.is_a?(Array)
+          value.flat_map.with_index do |v, idx|
+            serialize_attribute("#{key}.#{idx}", v)
+          end
+        elsif value.is_a?(TrueClass) || value.is_a?(FalseClass)
+          [[key, value.to_s]]
+        else
+          [[key, value]]
+        end
+      end
+
       private_class_method :id_rng, :reset!
 
       # The module handles bitwise operation for trace id
diff --git a/spec/datadog/tracing/span_link_spec.rb b/spec/datadog/tracing/span_link_spec.rb
index f840ef52819..6a0281038db 100644
--- a/spec/datadog/tracing/span_link_spec.rb
+++ b/spec/datadog/tracing/span_link_spec.rb
@@ -99,8 +99,16 @@
     end
 
     context 'with attributes' do
-      let(:options) { { span_id: 34, trace_id: 12, attributes: { 'link.name' => :test_link, 'link.id' => 1 } } }
-      it { is_expected.to include(attributes: { 'link.name' => 'test_link', 'link.id' => '1' }) }
+      let(:options) do
+        { span_id: 34, trace_id: 12,
+          attributes: { 'link.name' => :test_link, 'link.id' => 1, 'nested' => [true, [2, 3], 'val'] } }
+      end
+      it {
+        is_expected.to include(
+          attributes: { 'link.name' => 'test_link', 'link.id' => '1', 'nested.0' => 'true',
+                        'nested.1.0' => '2', 'nested.1.1' => '3', 'nested.2' => 'val', }
+        )
+      }
     end
   end
 end

From 78c39246bf93b61aeb5eeb14f8102ebb5f5784b1 Mon Sep 17 00:00:00 2001
From: Munir Abdinur <munir_abdinur@hotmail.com>
Date: Thu, 21 Mar 2024 11:54:02 -0400
Subject: [PATCH 3/6] update rbs and clean up to hash

---
 lib/datadog/tracing/span_link.rb  | 24 +++++----
 sig/datadog/tracing/span_link.rbs | 82 +------------------------------
 2 files changed, 15 insertions(+), 91 deletions(-)

diff --git a/lib/datadog/tracing/span_link.rb b/lib/datadog/tracing/span_link.rb
index 1c85a00f533..6874f871060 100644
--- a/lib/datadog/tracing/span_link.rb
+++ b/lib/datadog/tracing/span_link.rb
@@ -8,16 +8,24 @@ class SpanLink
       # @!attribute [r] span_id
       #   Datadog id for the currently active span.
       #   @return [Integer]
+      attr_reader :span_id
+
       # @!attribute [r] trace_id
       #   Datadog id for the currently active trace.
       #   @return [Integer]
+      attr_reader :trace_id
+
       # @!attribute [r] attributes
       #   Datadog-specific tags that support richer distributed tracing association.
       #   @return [Hash<String,String>]
+      attr_reader :attributes
+
       # @!attribute [r] trace_flags
       #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
       #   @return [Integer]
       #   @see https://www.w3.org/TR/trace-context/#trace-flags
+      attr_reader :trace_flags
+
       # @!attribute [r] trace_state
       #   The W3C "tracestate" extracted from a distributed context.
       #   This field is a string representing vendor-specific distribution data.
@@ -25,12 +33,7 @@ class SpanLink
       #   on every propagation injection.
       #   @return [String]
       #   @see https://www.w3.org/TR/trace-context/#tracestate-header
-      attr_reader \
-        :span_id,
-        :trace_id,
-        :attributes,
-        :trace_flags,
-        :trace_state
+      attr_reader :trace_state
 
       def initialize(
         span_id: nil,
@@ -54,6 +57,7 @@ def to_hash
           trace_id: Tracing::Utils::TraceId.to_low_order(@trace_id),
 
         }
+        # Optimization: Hash non empty attributes
         if @trace_id.to_i > Tracing::Utils::EXTERNAL_MAX_ID
           h[:trace_id_high] =
             Tracing::Utils::TraceId.to_high_order(@trace_id)
@@ -62,7 +66,7 @@ def to_hash
           h[:attributes] = {}
           @attributes.each do |k1, v1|
             Tracing::Utils.serialize_attribute(k1, v1).each do |new_k1, value|
-              h[:attributes][new_k1.to_s] = value.to_s
+              h[:attributes][new_k1] = value.to_s
             end
           end
         end
@@ -70,10 +74,10 @@ def to_hash
         h[:tracestate] = @trace_state if @trace_state
         # If traceflags set, the high bit (bit 31) should be set to 1 (uint32).
         # This helps us distinguish between when the sample decision is zero or not set
-        h[:flags] = if @trace_flags
-                      @trace_flags | (1 << 31)
-                    else
+        h[:flags] = if @trace_flags.nil?
                       0
+                    else
+                      @trace_flags | (1 << 31)
                     end
         h
       end
diff --git a/sig/datadog/tracing/span_link.rbs b/sig/datadog/tracing/span_link.rbs
index 558a561acfb..45815625410 100644
--- a/sig/datadog/tracing/span_link.rbs
+++ b/sig/datadog/tracing/span_link.rbs
@@ -18,104 +18,24 @@ module Datadog
       # @!attribute [r] span_id
       #   Datadog id for the currently active span.
       #   @return [Integer]
-      # @!attribute [r] trace_id
-      #   Datadog id for the currently active trace.
-      #   @return [Integer]
-      # @!attribute [r] attributes
-      #   Datadog-specific tags that support richer distributed tracing association.
-      #   @return [Hash<String,String>]
-      # @!attribute [r] trace_flags
-      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
-      #   @return [Integer]
-      #   @see https://www.w3.org/TR/trace-context/#trace-flags
-      # @!attribute [r] trace_state
-      #   The W3C "tracestate" extracted from a distributed context.
-      #   This field is a string representing vendor-specific distribution data.
-      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
-      #   on every propagation injection.
-      #   @return [String]
-      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader span_id: untyped
 
-      # @!attribute [r] span_id
-      #   Datadog id for the currently active span.
-      #   @return [Integer]
       # @!attribute [r] trace_id
       #   Datadog id for the currently active trace.
       #   @return [Integer]
-      # @!attribute [r] attributes
-      #   Datadog-specific tags that support richer distributed tracing association.
-      #   @return [Hash<String,String>]
-      # @!attribute [r] trace_flags
-      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
-      #   @return [Integer]
-      #   @see https://www.w3.org/TR/trace-context/#trace-flags
-      # @!attribute [r] trace_state
-      #   The W3C "tracestate" extracted from a distributed context.
-      #   This field is a string representing vendor-specific distribution data.
-      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
-      #   on every propagation injection.
-      #   @return [String]
-      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader trace_id: untyped
 
-      # @!attribute [r] span_id
-      #   Datadog id for the currently active span.
-      #   @return [Integer]
-      # @!attribute [r] trace_id
-      #   Datadog id for the currently active trace.
-      #   @return [Integer]
       # @!attribute [r] attributes
       #   Datadog-specific tags that support richer distributed tracing association.
       #   @return [Hash<String,String>]
-      # @!attribute [r] trace_flags
-      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
-      #   @return [Integer]
-      #   @see https://www.w3.org/TR/trace-context/#trace-flags
-      # @!attribute [r] trace_state
-      #   The W3C "tracestate" extracted from a distributed context.
-      #   This field is a string representing vendor-specific distribution data.
-      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
-      #   on every propagation injection.
-      #   @return [String]
-      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader attributes: untyped
 
-      # @!attribute [r] span_id
-      #   Datadog id for the currently active span.
-      #   @return [Integer]
-      # @!attribute [r] trace_id
-      #   Datadog id for the currently active trace.
-      #   @return [Integer]
-      # @!attribute [r] attributes
-      #   Datadog-specific tags that support richer distributed tracing association.
-      #   @return [Hash<String,String>]
       # @!attribute [r] trace_flags
       #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
       #   @return [Integer]
       #   @see https://www.w3.org/TR/trace-context/#trace-flags
-      # @!attribute [r] trace_state
-      #   The W3C "tracestate" extracted from a distributed context.
-      #   This field is a string representing vendor-specific distribution data.
-      #   The `dd=` entry is removed from `trace_state` as its value is dynamically calculated
-      #   on every propagation injection.
-      #   @return [String]
-      #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader trace_flags: untyped
 
-      # @!attribute [r] span_id
-      #   Datadog id for the currently active span.
-      #   @return [Integer]
-      # @!attribute [r] trace_id
-      #   Datadog id for the currently active trace.
-      #   @return [Integer]
-      # @!attribute [r] attributes
-      #   Datadog-specific tags that support richer distributed tracing association.
-      #   @return [Hash<String,String>]
-      # @!attribute [r] trace_flags
-      #   The W3C "trace-flags" extracted from a distributed context. This field is an 8-bit unsigned integer.
-      #   @return [Integer]
-      #   @see https://www.w3.org/TR/trace-context/#trace-flags
       # @!attribute [r] trace_state
       #   The W3C "tracestate" extracted from a distributed context.
       #   This field is a string representing vendor-specific distribution data.
@@ -130,4 +50,4 @@ module Datadog
       def to_hash: () -> untyped
     end
   end
-end
\ No newline at end of file
+end

From dd0a2318db29ec7f5367725a722db76aa69b188e Mon Sep 17 00:00:00 2001
From: Munir Abdinur <munir_abdinur@hotmail.com>
Date: Thu, 21 Mar 2024 14:09:18 -0400
Subject: [PATCH 4/6] use digest as argument

---
 lib/datadog/opentelemetry/sdk/trace/span.rb   |   2 +-
 lib/datadog/tracing/span_link.rb              |  23 ++--
 sig/datadog/tracing/span_link.rbs             |   6 +-
 sig/datadog/tracing/utils.rbs                 |   5 +-
 spec/datadog/tracing/span_link_spec.rb        | 105 ++++++++++--------
 .../transport/serializable_trace_spec.rb      |  36 ++++--
 6 files changed, 102 insertions(+), 75 deletions(-)

diff --git a/lib/datadog/opentelemetry/sdk/trace/span.rb b/lib/datadog/opentelemetry/sdk/trace/span.rb
index 797809c36d2..6bf30657193 100644
--- a/lib/datadog/opentelemetry/sdk/trace/span.rb
+++ b/lib/datadog/opentelemetry/sdk/trace/span.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require '../../../tracing/utils'
+require 'datadog/tracing/utils'
 
 module Datadog
   module OpenTelemetry
diff --git a/lib/datadog/tracing/span_link.rb b/lib/datadog/tracing/span_link.rb
index 6874f871060..f911d982dcb 100644
--- a/lib/datadog/tracing/span_link.rb
+++ b/lib/datadog/tracing/span_link.rb
@@ -36,33 +36,28 @@ class SpanLink
       attr_reader :trace_state
 
       def initialize(
-        span_id: nil,
-        trace_id: nil,
         attributes: nil,
-        trace_flags: nil,
-        trace_state: nil
+        digest: nil
       )
-        @span_id = span_id
-        @trace_id = trace_id
-        @attributes = attributes && attributes.dup.freeze
-        @trace_flags = trace_flags
-        @trace_state = trace_state && trace_state.dup.freeze
+        @span_id = digest&.span_id
+        @trace_id = digest&.trace_id
+        @trace_flags = digest&.trace_flags
+        @trace_state = digest&.trace_state && digest&.trace_state.dup
         @dropped_attributes = 0
-        freeze
+        @attributes = (attributes && attributes.dup) || {}
       end
 
       def to_hash
         h = {
-          span_id: @span_id,
-          trace_id: Tracing::Utils::TraceId.to_low_order(@trace_id),
-
+          span_id: @span_id || 0,
+          trace_id: Tracing::Utils::TraceId.to_low_order(@trace_id) || 0,
         }
         # Optimization: Hash non empty attributes
         if @trace_id.to_i > Tracing::Utils::EXTERNAL_MAX_ID
           h[:trace_id_high] =
             Tracing::Utils::TraceId.to_high_order(@trace_id)
         end
-        if @attributes
+        unless @attributes&.empty?
           h[:attributes] = {}
           @attributes.each do |k1, v1|
             Tracing::Utils.serialize_attribute(k1, v1).each do |new_k1, value|
diff --git a/sig/datadog/tracing/span_link.rbs b/sig/datadog/tracing/span_link.rbs
index 45815625410..2889beaed02 100644
--- a/sig/datadog/tracing/span_link.rbs
+++ b/sig/datadog/tracing/span_link.rbs
@@ -7,14 +7,14 @@ module Datadog
 
       @trace_id: untyped
 
-      @attributes: untyped
-
       @trace_flags: untyped
 
       @trace_state: untyped
 
       @dropped_attributes: untyped
 
+      @attributes: untyped
+
       # @!attribute [r] span_id
       #   Datadog id for the currently active span.
       #   @return [Integer]
@@ -45,7 +45,7 @@ module Datadog
       #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader trace_state: untyped
 
-      def initialize: (?span_id: untyped?, ?trace_id: untyped?, ?attributes: untyped?, ?trace_flags: untyped?, ?trace_state: untyped?) -> void
+      def initialize: (?attributes: untyped?, ?digest: untyped?) -> void
 
       def to_hash: () -> untyped
     end
diff --git a/sig/datadog/tracing/utils.rbs b/sig/datadog/tracing/utils.rbs
index b20ac2dbc97..589493e4180 100644
--- a/sig/datadog/tracing/utils.rbs
+++ b/sig/datadog/tracing/utils.rbs
@@ -10,6 +10,9 @@ module Datadog
       def self.id_rng: () -> untyped
 
       def self.reset!: () -> untyped
+
+      def self.serialize_attribute: (untyped key, untyped value) -> (untyped | ::Array[::Array[untyped]])
+
       module TraceId
         MAX: untyped
         def self?.next_id: () -> untyped
@@ -22,4 +25,4 @@ module Datadog
       end
     end
   end
-end
+end
\ No newline at end of file
diff --git a/spec/datadog/tracing/span_link_spec.rb b/spec/datadog/tracing/span_link_spec.rb
index 6a0281038db..6094a1de9c9 100644
--- a/spec/datadog/tracing/span_link_spec.rb
+++ b/spec/datadog/tracing/span_link_spec.rb
@@ -2,107 +2,116 @@
 require 'support/object_helpers'
 
 require 'datadog/tracing/span_link'
+require 'datadog/tracing/trace_digest'
 
 RSpec.describe Datadog::Tracing::SpanLink do
-  subject(:span_link) { described_class.new(**options) }
-  let(:options) { {} }
+  subject(:span_link) { described_class.new(attributes: attributes, digest: digest) }
+
+  let(:attributes) { nil }
+  let(:digest) do
+    Datadog::Tracing::TraceDigest.new(
+      span_id: span_id,
+      trace_id: trace_id,
+      trace_flags: trace_flags,
+      trace_state: trace_state,
+    )
+  end
+  let(:span_id) { nil }
+  let(:trace_id) { nil }
+  let(:trace_state) { nil }
+  let(:trace_flags) { nil }
 
   describe '::new' do
     context 'by default' do
+      let(:digest) { nil }
+      let(:attributes) { nil }
+
       it do
         is_expected.to have_attributes(
           span_id: nil,
-          attributes: nil,
+          attributes: {},
           trace_id: nil,
           trace_flags: nil,
           trace_state: nil,
         )
       end
-
-      it { is_expected.to be_frozen }
     end
 
     context 'given' do
-      context ':span_id' do
-        let(:options) { { span_id: span_id } }
-        let(:span_id) { Datadog::Tracing::Utils.next_id }
-
-        it { is_expected.to have_attributes(span_id: span_id) }
-      end
-
       context ':attributes' do
-        let(:options) { { attributes: attributes } }
         let(:attributes) { { tag: 'value' } }
-
-        it { is_expected.to have_attributes(attributes: be_a_frozen_copy_of(attributes)) }
-      end
-
-      context ':trace_id' do
-        let(:options) { { trace_id: trace_id } }
-        let(:trace_id) { Datadog::Tracing::Utils::TraceId.next_id }
-
-        it { is_expected.to have_attributes(trace_id: trace_id) }
+        it { is_expected.to have_attributes(attributes: attributes) }
       end
 
-      context ':trace_flags' do
-        let(:options) { { trace_flags: trace_flags } }
-        let(:trace_flags) { 0x01 }
-
-        it { is_expected.to have_attributes(trace_flags: 0x01) }
-      end
-
-      context ':trace_state' do
-        let(:options) { { trace_state: trace_state } }
-        let(:trace_state) { 'vendor1=value,v2=v' }
-
-        it { is_expected.to have_attributes(trace_state: be_a_frozen_copy_of('vendor1=value,v2=v')) }
+      context ':digest with' do
+        context ':span_id' do
+          let(:span_id) { Datadog::Tracing::Utils.next_id }
+          it { is_expected.to have_attributes(span_id: span_id) }
+        end
+
+        context ':trace_id' do
+          let(:trace_id) { Datadog::Tracing::Utils::TraceId.next_id }
+          it { is_expected.to have_attributes(trace_id: trace_id) }
+        end
+
+        context ':trace_flags' do
+          let(:trace_flags) { 0x01 }
+          it { is_expected.to have_attributes(trace_flags: 0x01) }
+        end
+
+        context ':trace_state' do
+          let(:trace_state) { 'vendor1=value,v2=v' }
+          it { is_expected.to have_attributes(trace_state: 'vendor1=value,v2=v') }
+        end
       end
     end
   end
 
   describe '#to_hash' do
     subject(:to_hash) { span_link.to_hash }
+    let(:span_id) { 34 }
+    let(:trace_id) { 12 }
 
     context 'with required fields' do
-      let(:options) { { span_id: 34, trace_id: 12 } }
-
       context 'when trace_id < 2^64' do
         it { is_expected.to eq(trace_id: 12, span_id: 34, flags: 0) }
       end
 
       context 'when trace_id >= 2^64' do
-        let(:options) { { span_id: 34, trace_id: 2**64 + 12 } }
+        let(:trace_id) { 2**64 + 12 }
         it { is_expected.to eq(trace_id: 12, trace_id_high: 1, span_id: 34, flags: 0) }
       end
     end
 
-    context 'with trace_state' do
-      let(:options) { { span_id: 34, trace_id: 12, trace_state: 'dd=s:1' } }
+    context 'required fields are set to nil' do
+      let(:span_id) { nil }
+      let(:trace_id) { nil }
+      it { is_expected.to eq(trace_id: 0, span_id: 0, flags: 0) }
+    end
+
+    context 'when trace_state is set' do
+      let(:trace_state) { 'dd=s:1' }
       it { is_expected.to include(tracestate: 'dd=s:1') }
     end
 
-    context 'with trace_flag' do
+    context 'when trace_flag is set' do
       context 'when trace_flag is unset' do
-        let(:options) { { span_id: 34, trace_id: 12 } }
         it { is_expected.to include(flags: 0) }
       end
 
       context 'when trace_flags is 0' do
-        let(:options) { { span_id: 34, trace_id: 12, trace_flags: 0 } }
+        let(:trace_flags) { 0 }
         it { is_expected.to include(flags: 2147483648) }
       end
 
       context 'when trace_flag is 1' do
-        let(:options) { { span_id: 34, trace_id: 12, trace_flags: 1 } }
+        let(:trace_flags) { 1 }
         it { is_expected.to include(flags: 2147483649) }
       end
     end
 
-    context 'with attributes' do
-      let(:options) do
-        { span_id: 34, trace_id: 12,
-          attributes: { 'link.name' => :test_link, 'link.id' => 1, 'nested' => [true, [2, 3], 'val'] } }
-      end
+    context 'when attributes is set' do
+      let(:attributes) { { 'link.name' => :test_link, 'link.id' => 1, 'nested' => [true, [2, 3], 'val'] } }
       it {
         is_expected.to include(
           attributes: { 'link.name' => 'test_link', 'link.id' => '1', 'nested.0' => 'true',
diff --git a/spec/datadog/tracing/transport/serializable_trace_spec.rb b/spec/datadog/tracing/transport/serializable_trace_spec.rb
index 4c961117e24..e558f24770f 100644
--- a/spec/datadog/tracing/transport/serializable_trace_spec.rb
+++ b/spec/datadog/tracing/transport/serializable_trace_spec.rb
@@ -78,13 +78,26 @@
         Array.new(3) do |_i|
           Datadog::Tracing::Span.new(
             'dummy',
-            links: [Datadog::Tracing::SpanLink.new(
-              trace_id: 0xaaaaaaaaaaaaaaaaffffffffffffffff,
-              span_id: 0x1,
-              trace_state: 'vendor1=value,v2=v,dd=s:1',
-              trace_flags: 0x1,
-              attributes: { 'link.name' => 'test_link' }
-            )]
+            links: [
+              Datadog::Tracing::SpanLink.new(
+                digest: Datadog::Tracing::TraceDigest.new(
+                  trace_id: 0xaaaaaaaaaaaaaaaaffffffffffffffff,
+                  span_id: 0x1,
+                  trace_state: 'vendor1=value,v2=v,dd=s:1',
+                  trace_flags: 0x1,
+                ),
+                attributes: { 'link.name' => 'test_link' }
+              ),
+              Datadog::Tracing::SpanLink.new(
+                digest: Datadog::Tracing::TraceDigest.new(
+                  trace_id: 0xa0123456789abcdef,
+                  span_id: 0x2,
+                ),
+              ),
+              Datadog::Tracing::SpanLink.new(
+                digest: Datadog::Tracing::TraceDigest.new,
+              )
+            ],
           )
         end
       end
@@ -103,7 +116,14 @@
               'attributes' => { 'link.name' => 'test_link' },
               'flags' => 2147483649,
               'tracestate' => 'vendor1=value,v2=v,dd=s:1',
-            }]
+            },
+             {
+               'span_id' => 2,
+               'trace_id' => 0x0123456789abcdef,
+               'trace_id_high' => 10,
+               'flags' => 0
+             },
+             { 'span_id' => 0, 'trace_id' => 0, 'flags' => 0 }]
           )
         )
       end

From c594f9458ad7f1df74a0ed690f4cd362990d35ba Mon Sep 17 00:00:00 2001
From: Munir Abdinur <munir.abdinur@datadoghq.com>
Date: Thu, 21 Mar 2024 18:48:02 -0400
Subject: [PATCH 5/6] Apply suggestions from code review

---
 spec/datadog/tracing/span_link_spec.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spec/datadog/tracing/span_link_spec.rb b/spec/datadog/tracing/span_link_spec.rb
index 6094a1de9c9..d9e1dcdce8d 100644
--- a/spec/datadog/tracing/span_link_spec.rb
+++ b/spec/datadog/tracing/span_link_spec.rb
@@ -83,7 +83,7 @@
       end
     end
 
-    context 'required fields are set to nil' do
+    context 'when required fields are not set' do
       let(:span_id) { nil }
       let(:trace_id) { nil }
       it { is_expected.to eq(trace_id: 0, span_id: 0, flags: 0) }

From c6431dd1a2f4c5c1109927271e585d4d37d22831 Mon Sep 17 00:00:00 2001
From: Munir Abdinur <munir_abdinur@hotmail.com>
Date: Sat, 30 Mar 2024 04:16:34 +0300
Subject: [PATCH 6/6] review comments

---
 lib/datadog/tracing/span.rb                         | 2 +-
 lib/datadog/tracing/span_link.rb                    | 5 +++++
 lib/datadog/tracing/transport/serializable_trace.rb | 2 +-
 sig/datadog/tracing/span_link.rbs                   | 5 +++++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/datadog/tracing/span.rb b/lib/datadog/tracing/span.rb
index 187d25c31e1..57f156dcef1 100644
--- a/lib/datadog/tracing/span.rb
+++ b/lib/datadog/tracing/span.rb
@@ -141,7 +141,7 @@ def to_hash
           span_id: @id,
           trace_id: @trace_id,
           type: @type,
-          span_links: @links.map!(&:to_hash)
+          span_links: @links.map(&:to_hash)
         }
 
         if stopped?
diff --git a/lib/datadog/tracing/span_link.rb b/lib/datadog/tracing/span_link.rb
index f911d982dcb..8194b2e1c46 100644
--- a/lib/datadog/tracing/span_link.rb
+++ b/lib/datadog/tracing/span_link.rb
@@ -35,6 +35,11 @@ class SpanLink
       #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader :trace_state
 
+      # @!attribute [r] dropped_attributes
+      #   The number of attributes that were discarded due to serialization limits.
+      #   @return [Integer]
+      attr_reader :dropped_attributes
+
       def initialize(
         attributes: nil,
         digest: nil
diff --git a/lib/datadog/tracing/transport/serializable_trace.rb b/lib/datadog/tracing/transport/serializable_trace.rb
index 44cfb696280..b056af71c2a 100644
--- a/lib/datadog/tracing/transport/serializable_trace.rb
+++ b/lib/datadog/tracing/transport/serializable_trace.rb
@@ -94,7 +94,7 @@ def to_msgpack(packer = nil)
           packer.write('metrics')
           packer.write(span.metrics)
           packer.write('span_links')
-          packer.write(span.links.map!(&:to_hash))
+          packer.write(span.links.map(&:to_hash))
           packer.write('error')
           packer.write(span.status)
           packer
diff --git a/sig/datadog/tracing/span_link.rbs b/sig/datadog/tracing/span_link.rbs
index 2889beaed02..e2dcc49aef1 100644
--- a/sig/datadog/tracing/span_link.rbs
+++ b/sig/datadog/tracing/span_link.rbs
@@ -45,6 +45,11 @@ module Datadog
       #   @see https://www.w3.org/TR/trace-context/#tracestate-header
       attr_reader trace_state: untyped
 
+      # @!attribute [r] dropped_attributes
+      #   The number of attributes that were discarded due to serialization limits.
+      #   @return [Integer]
+      attr_reader dropped_attributes: untyped
+
       def initialize: (?attributes: untyped?, ?digest: untyped?) -> void
 
       def to_hash: () -> untyped