Module: Datadog::DistributedTracing::Headers::Helpers

Defined in:
lib/ddtrace/distributed_tracing/headers/helpers.rb

Overview

Helpers module provides common helper functions for distributed tracing headers

Class Method Summary collapse

Class Method Details

.clamp_sampling_priority(sampling_priority) ⇒ Object

Base provides common methods for distributed header helper classes



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# File 'lib/ddtrace/distributed_tracing/headers/helpers.rb', line 11

def self.clamp_sampling_priority(sampling_priority)
  # B3 doesn't have our -1 (USER_REJECT) and 2 (USER_KEEP) priorities so convert to acceptable 0/1
  if sampling_priority < 0
    sampling_priority = Ext::Priority::AUTO_REJECT
  elsif sampling_priority > 1
    sampling_priority = Ext::Priority::AUTO_KEEP
  end

  sampling_priority
end

.truncate_base16_number(value) ⇒ Object 



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# File 'lib/ddtrace/distributed_tracing/headers/helpers.rb', line 22

def self.truncate_base16_number(value)
  # Lowercase if we want to parse base16 e.g. 3E8 => 3e8
  # DEV: Ruby will parse `3E8` just fine, but to test
  #      `num.to_s(base) == value` we need to lowercase
  value = value.downcase

  # Truncate to trailing 16 characters if length is greater than 16
  # https://github.com/apache/incubator-zipkin/blob/21fe362899fef5c593370466bc5707d3837070c2/zipkin/src/main/java/zipkin2/storage/StorageComponent.java#L49-L53
  # DEV: This ensures we truncate B3 128-bit trace and span ids to 64-bit
  value = value[value.length - 16, 16] if value.length > 16

  # Remove any leading zeros
  # DEV: When we call `num.to_s(16)` later Ruby will not add leading zeros
  #      for us so we want to make sure the comparision will work as expected
  # DEV: regex, remove all leading zeros up until we find the last 0 in the string
  #      or we find the first non-zero, this allows `'0000' -> '0'` and `'00001' -> '1'`
  value = value.sub(/^0*(?=(0$)|[^0])/, '')

  value
end