Module: Datadog::OpenTracer::TextMapPropagator

Extended by:
Propagator
Defined in:
lib/datadog/opentracer/text_map_propagator.rb

Overview

OpenTracing propagator for Datadog::OpenTracer::Tracer

Constant Summary collapse

BAGGAGE_PREFIX = 
'ot-baggage-'.freeze

Class Method Summary collapse

Methods included from Propagator

extract, inject

Class Method Details

.extract(carrier) ⇒ SpanContext?

Extract a SpanContext in TextMap format from the given carrier.

Parameters:

  • carrier (Carrier) —

    A carrier object of TextMap type

Returns:

  • (SpanContext, nil) —

    the extracted SpanContext or nil if none could be found



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# File 'lib/datadog/opentracer/text_map_propagator.rb', line 46

def extract(carrier)
  # First extract & build a Datadog context
  headers = DistributedHeaders.new(carrier)
  datadog_trace_digest = headers_to_trace_digest(headers)

  # Then extract any other baggage
  baggage = {}
  carrier.each do |key, value|
    baggage[item_to_baggage(key)] = value if baggage_item?(key)
  end

  SpanContextFactory.build(
    datadog_context: nil,
    datadog_trace_digest: datadog_trace_digest,
    baggage: baggage
  )
end

.inject(span_context, carrier) ⇒ Object

Inject a SpanContext into the given carrier

Parameters:



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# File 'lib/datadog/opentracer/text_map_propagator.rb', line 19

def inject(span_context, carrier)
  # Inject baggage
  span_context.baggage.each do |key, value|
    carrier[BAGGAGE_PREFIX + key] = value
  end

  # Inject Datadog trace properties
  digest = if span_context.datadog_context && span_context.datadog_context.active_trace
             span_context.datadog_context.active_trace.to_digest
           else
             span_context.datadog_trace_digest
           end
  return unless digest

  carrier[Tracing::Distributed::Datadog::ORIGIN_KEY] = digest.trace_origin
  carrier[Tracing::Distributed::Datadog::PARENT_ID_KEY] = digest.span_id
  carrier[Tracing::Distributed::Datadog::SAMPLING_PRIORITY_KEY] = digest.trace_sampling_priority
  carrier[Tracing::Distributed::Datadog::TRACE_ID_KEY] =
    Datadog::Tracing::Utils::TraceId.to_low_order(digest.trace_id)

  nil
end