Merge pull request #2463 from DataDog/refactor/extract_utils_tracing_…

…next_id

Move Utils#next_id and constants to Tracing::Utils

lib/datadog/core/utils.rb

@@ -1,7 +1,6 @@
 # typed: true
 
 require_relative 'utils/forking'
-require_relative '../tracing/span'
 
 module Datadog
   module Core
@@ -11,26 +10,6 @@ module Utils
       extend Forking
 
       EMPTY_STRING = ''.encode(::Encoding::UTF_8).freeze
-      # We use a custom random number generator because we want no interference
-      # with the default one. Using the default prng, we could break code that
-      # would rely on srand/rand sequences.
-
-      # Return a randomly generated integer, valid as a Span ID or Trace ID.
-      # This method is thread-safe and fork-safe.
-      def self.next_id
-        after_fork! { reset! }
-        id_rng.rand(Tracing::Span::RUBY_ID_RANGE)
-      end
-
-      def self.id_rng
-        @id_rng ||= Random.new
-      end
-
-      def self.reset!
-        @id_rng = Random.new
-      end
-
-      private_class_method :id_rng, :reset!
 
       # Stringifies `value` and ensures the outcome is
       # string is no longer than `size`.

lib/datadog/opentracer/distributed_headers.rb

@@ -1,7 +1,7 @@
 # typed: true
 
-require_relative '../tracing/span'
 require_relative '../tracing/distributed/datadog'
+require_relative '../tracing/utils'
 
 module Datadog
   module OpenTracer
@@ -47,7 +47,7 @@ def origin
 
       def id(header)
         value = @carrier[header].to_i
-        return if value.zero? || value >= Datadog::Tracing::Span::EXTERNAL_MAX_ID
+        return if value.zero? || value >= Datadog::Tracing::Utils::EXTERNAL_MAX_ID
 
         value < 0 ? value + 0x1_0000_0000_0000_0000 : value
       end

lib/datadog/tracing/distributed/helpers.rb

@@ -2,6 +2,7 @@
 # typed: true
 
 require_relative '../sampling/ext'
+require_relative '../utils'
 
 module Datadog
   module Tracing
@@ -47,7 +48,7 @@ def self.value_to_id(value, base = 10)
           return if id.nil?
 
           # Zero or greater than max allowed value of 2**64
-          return if id.zero? || id > Span::EXTERNAL_MAX_ID
+          return if id.zero? || id > Tracing::Utils::EXTERNAL_MAX_ID
 
           id < 0 ? id + (2**64) : id
         end

lib/datadog/tracing/sampling/rate_sampler.rb

@@ -3,7 +3,7 @@
 require_relative '../../core'
 
 require_relative 'sampler'
-require_relative '../span'
+require_relative '../utils'
 
 module Datadog
   module Tracing
@@ -49,11 +49,11 @@ def sample_rate(*_)
 
         def sample_rate=(sample_rate)
           @sample_rate = sample_rate
-          @sampling_id_threshold = sample_rate * Tracing::Span::EXTERNAL_MAX_ID
+          @sampling_id_threshold = sample_rate * Tracing::Utils::EXTERNAL_MAX_ID
         end
 
         def sample?(trace)
-          ((trace.id * KNUTH_FACTOR) % Tracing::Span::EXTERNAL_MAX_ID) <= @sampling_id_threshold
+          ((trace.id * KNUTH_FACTOR) % Tracing::Utils::EXTERNAL_MAX_ID) <= @sampling_id_threshold
         end
 
         def sample!(trace)

lib/datadog/tracing/span.rb

@@ -2,8 +2,8 @@
 
 # typed: true
 
-require_relative '../core/utils'
 require_relative '../core/utils/safe_dup'
+require_relative 'utils'
 
 require_relative 'metadata/ext'
 require_relative 'metadata'
@@ -19,22 +19,6 @@ module Tracing
     class Span
       include Metadata
 
-      # The max value for a {Datadog::Tracing::Span} identifier.
-      # Span and trace identifiers should be strictly positive and strictly inferior to this limit.
-      #
-      # Limited to +2<<62-1+ positive integers, as Ruby is able to represent such numbers "inline",
-      # inside a +VALUE+ scalar, thus not requiring memory allocation.
-      #
-      # The range of IDs also has to consider portability across different languages and platforms.
-      RUBY_MAX_ID = (1 << 62) - 1
-
-      # Excludes zero from possible values
-      RUBY_ID_RANGE = (1..RUBY_MAX_ID).freeze
-
-      # While we only generate 63-bit integers due to limitations in other languages, we support
-      # parsing 64-bit integers for distributed tracing since an upstream system may generate one
-      EXTERNAL_MAX_ID = 1 << 64
-
       attr_accessor \
         :end_time,
         :id,
@@ -90,9 +74,9 @@ def initialize(
         @resource = Core::Utils::SafeDup.frozen_or_dup(resource)
         @type = Core::Utils::SafeDup.frozen_or_dup(type)
 
-        @id = id || Core::Utils.next_id
+        @id = id || Tracing::Utils.next_id
         @parent_id = parent_id || 0
-        @trace_id = trace_id || Core::Utils.next_id
+        @trace_id = trace_id || Tracing::Utils.next_id
 
         @meta = meta || {}
         @metrics = metrics || {}

lib/datadog/tracing/span_operation.rb

@@ -7,10 +7,11 @@
 require_relative '../core/utils'
 require_relative '../core/utils/time'
 
-require_relative 'metadata/ext'
 require_relative 'event'
-require_relative 'span'
 require_relative 'metadata'
+require_relative 'metadata/ext'
+require_relative 'span'
+require_relative 'utils'
 
 module Datadog
   module Tracing
@@ -61,9 +62,9 @@ def initialize(
         self.type = type
         self.resource = resource
 
-        @id = Core::Utils.next_id
+        @id = Tracing::Utils.next_id
         @parent_id = parent_id || 0
-        @trace_id = trace_id || Core::Utils.next_id
+        @trace_id = trace_id || Tracing::Utils.next_id
 
         @status = 0
 

lib/datadog/tracing/trace_operation.rb

@@ -4,12 +4,13 @@
 require_relative '../core/environment/identity'
 require_relative '../core/utils'
 
-require_relative 'sampling/ext'
 require_relative 'event'
+require_relative 'metadata/tagging'
+require_relative 'sampling/ext'
 require_relative 'span_operation'
-require_relative 'trace_segment'
 require_relative 'trace_digest'
-require_relative 'metadata/tagging'
+require_relative 'trace_segment'
+require_relative 'utils'
 
 module Datadog
   module Tracing
@@ -70,7 +71,7 @@ def initialize(
         metrics: nil
       )
         # Attributes
-        @id = id || Core::Utils.next_id
+        @id = id || Tracing::Utils.next_id
         @max_length = max_length || DEFAULT_MAX_LENGTH
         @parent_span_id = parent_span_id
         @sampled = sampled.nil? ? true : sampled

lib/datadog/tracing/utils.rb

@@ -0,0 +1,50 @@
+# typed: true
+
+require_relative '../core/utils/forking'
+
+module Datadog
+  module Tracing
+    # Utils contains low-level tracing utility functions.
+    # @public_api
+    module Utils
+      extend Datadog::Core::Utils::Forking
+
+      # The max value for a {Datadog::Tracing::Span} identifier.
+      # Span and trace identifiers should be strictly positive and strictly inferior to this limit.
+      #
+      # Limited to +2<<62-1+ positive integers, as Ruby is able to represent such numbers "inline",
+      # inside a +VALUE+ scalar, thus not requiring memory allocation.
+      #
+      # The range of IDs also has to consider portability across different languages and platforms.
+      RUBY_MAX_ID = (1 << 62) - 1
+
+      # Excludes zero from possible values
+      RUBY_ID_RANGE = (1..RUBY_MAX_ID).freeze
+
+      # While we only generate 63-bit integers due to limitations in other languages, we support
+      # parsing 64-bit integers for distributed tracing since an upstream system may generate one
+      EXTERNAL_MAX_ID = 1 << 64
+
+      # We use a custom random number generator because we want no interference
+      # with the default one. Using the default prng, we could break code that
+      # would rely on srand/rand sequences.
+
+      # Return a randomly generated integer, valid as a Span ID or Trace ID.
+      # This method is thread-safe and fork-safe.
+      def self.next_id
+        after_fork! { reset! }
+        id_rng.rand(RUBY_ID_RANGE)
+      end
+
+      def self.id_rng
+        @id_rng ||= Random.new
+      end
+
+      def self.reset!
+        @id_rng = Random.new
+      end
+
+      private_class_method :id_rng, :reset!
+    end
+  end
+end

spec/datadog/core/utils_spec.rb

@@ -6,34 +6,6 @@
 require 'datadog/core/utils'
 
 RSpec.describe Datadog::Core::Utils do
-  describe '.next_id' do
-    subject(:next_id) { described_class.next_id }
-
-    it 'returns a positive integer smaller than 2**62' do
-      is_expected.to be_a(Integer)
-      is_expected.to be_between(1, 2**62 - 1)
-    end
-
-    it 'fits in a CRuby VALUE slot', if: ObjectSpaceHelper.estimate_bytesize_supported? do
-      expect(ObjectSpaceHelper.estimate_bytesize(next_id)).to eq(0)
-    end
-
-    it 'returns unique numbers on successive calls' do
-      is_expected.to_not eq(described_class.next_id)
-    end
-
-    context 'after forking', if: PlatformHelpers.supports_fork? do
-      it 'generates unique ids across forks' do
-        ids = Array.new(3) do
-          result = expect_in_fork { puts next_id }
-          Integer(result[:stdout])
-        end.uniq
-
-        expect(ids).to have(3).items
-      end
-    end
-  end
-
   describe '.truncate' do
     subject(:truncate) { described_class.truncate(value, size, omission) }
     let(:value) { 123456 }

spec/datadog/opentracer/distributed_headers_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-require 'datadog/tracing/span'
+require 'datadog/tracing/utils'
 require 'datadog/opentracer'
 
 RSpec.describe Datadog::OpenTracer::DistributedHeaders do
@@ -25,21 +25,21 @@
 
     context 'when #trace_id is missing' do
       let(:trace_id) { nil }
-      let(:parent_id) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID + 1).to_s }
+      let(:parent_id) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID + 1).to_s }
 
       it { is_expected.to be false }
     end
 
     context 'when #parent_id is missing' do
-      let(:trace_id) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID + 1).to_s }
+      let(:trace_id) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID + 1).to_s }
       let(:parent_id) { nil }
 
       it { is_expected.to be false }
     end
 
     context 'when both #trace_id and #parent_id are present' do
-      let(:trace_id) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID - 1).to_s }
-      let(:parent_id) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID - 1).to_s }
+      let(:trace_id) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 1).to_s }
+      let(:parent_id) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 1).to_s }
 
       it { is_expected.to be true }
     end
@@ -60,13 +60,13 @@
 
     context 'when the header is present' do
       context 'but the value is out of range' do
-        let(:value) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID + 1).to_s }
+        let(:value) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID + 1).to_s }
 
         it { is_expected.to be nil }
       end
 
       context 'and the value is in range' do
-        let(:value) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID - 1).to_s }
+        let(:value) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 1).to_s }
 
         it { is_expected.to eq value.to_i }
 
@@ -95,13 +95,13 @@
 
     context 'when the header is present' do
       context 'but the value is out of range' do
-        let(:value) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID + 1).to_s }
+        let(:value) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID + 1).to_s }
 
         it { is_expected.to be nil }
       end
 
       context 'and the value is in range' do
-        let(:value) { (Datadog::Tracing::Span::EXTERNAL_MAX_ID - 1).to_s }
+        let(:value) { (Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 1).to_s }
 
         it { is_expected.to eq value.to_i }
 

spec/datadog/opentracer/propagation_integration_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-require 'datadog/tracing/span'
+require 'datadog/tracing/utils'
 require 'datadog/opentracer'
 
 RSpec.describe 'OpenTracer context propagation' do
@@ -80,8 +80,8 @@ def baggage_to_carrier_format(baggage)
           )
         end
 
-        let(:trace_id) { Datadog::Tracing::Span::EXTERNAL_MAX_ID - 1 }
-        let(:parent_id) { Datadog::Tracing::Span::EXTERNAL_MAX_ID - 2 }
+        let(:trace_id) { Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 1 }
+        let(:parent_id) { Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 2 }
         let(:sampling_priority) { 2 }
         let(:origin) { 'synthetics' }
 
@@ -272,8 +272,8 @@ def baggage_to_carrier_format(baggage)
           )
         end
 
-        let(:trace_id) { Datadog::Tracing::Span::EXTERNAL_MAX_ID - 1 }
-        let(:parent_id) { Datadog::Tracing::Span::EXTERNAL_MAX_ID - 2 }
+        let(:trace_id) { Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 1 }
+        let(:parent_id) { Datadog::Tracing::Utils::EXTERNAL_MAX_ID - 2 }
         let(:sampling_priority) { 2 }
         let(:origin) { 'synthetics' }