Contents

# typed: false

require 'datadog/tracing/span'
require 'datadog/tracing/distributed/helpers'

module Datadog
  module Tracing
    module Distributed
      # Parser provides easy access and validation methods for Rack headers
      class Parser
        def initialize(env)
          @env = env
        end

        # TODO: Don't assume Rack format.
        #       Make distributed tracing headers apathetic.
        def header(name)
          rack_header = "http-#{name}".upcase!.tr('-', '_')

          hdr = @env[rack_header]

          # Only return the value if it is not an empty string
          hdr if hdr != ''
        end

        def id(hdr, base = 10)
          value_to_id(header(hdr), base)
        end

        def value_to_id(value, base = 10)
          id = value_to_number(value, base)

          # Return early if we could not parse a number
          return if id.nil?

          # Zero or greater than max allowed value of 2**64
          return if id.zero? || id > Span::EXTERNAL_MAX_ID

          id < 0 ? id + (2**64) : id
        end

        def number(hdr, base = 10)
          value_to_number(header(hdr), base)
        end

        def value_to_number(value, base = 10)
          # It's important to make a difference between no header,
          # and a header defined to zero.
          return if value.nil?

          # Be sure we have a string
          value = value.to_s

          # If we are parsing base16 number then truncate to 64-bit
          value = Helpers.truncate_base16_number(value) if base == 16

          # Convert header to an integer
          # DEV: Ruby `.to_i` will return `0` if a number could not be parsed
          num = value.to_i(base)

          # Ensure the parsed number is the same as the original string value
          # e.g. We want to make sure to throw away `'nan'.to_i == 0`
          return unless num.to_s(base) == value

          num
        end
      end
    end
  end
end

Version data entries

3 entries across 3 versions & 1 rubygems

Version	Path
ddtrace-1.1.0	lib/datadog/tracing/distributed/parser.rb
ddtrace-1.0.0	lib/datadog/tracing/distributed/parser.rb
ddtrace-1.0.0.beta2	lib/datadog/tracing/distributed/parser.rb