Class: Datadog::Tracing::Distributed::TraceContext

Inherits:
Object
  • Object
show all
Defined in:
lib/datadog/tracing/distributed/trace_context.rb

Overview

W3C Trace Context propagator implementation, version 00. The trace is propagated through two fields: ‘traceparent` and `tracestate`.

See Also:

Defined Under Namespace

Modules: Refine

Constant Summary collapse

TRACEPARENT_KEY = 
'traceparent'
TRACESTATE_KEY = 
'tracestate'
SPEC_VERSION = 
'00'

Instance Method Summary collapse

Constructor Details

#initialize(fetcher:, traceparent_key: TRACEPARENT_KEY, tracestate_key: TRACESTATE_KEY) ⇒ TraceContext

Returns a new instance of TraceContext.



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# File 'lib/datadog/tracing/distributed/trace_context.rb', line 14

def initialize(
  fetcher:,
  traceparent_key: TRACEPARENT_KEY,
  tracestate_key: TRACESTATE_KEY
)
  @fetcher = fetcher
  @traceparent_key = traceparent_key
  @tracestate_key = tracestate_key
end

Instance Method Details

#extract(data) ⇒ Object 



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# File 'lib/datadog/tracing/distributed/trace_context.rb', line 38

def extract(data)
  fetcher = @fetcher.new(data)

  trace_id, parent_id, sampled, trace_flags = extract_traceparent(fetcher[@traceparent_key])

  return unless trace_id # Could not parse traceparent

  tracestate, sampling_priority, origin, ts_parent_id, tags, unknown_fields = extract_tracestate(
    fetcher[@tracestate_key]
  )

  sampling_priority = parse_priority_sampling(sampled, sampling_priority) do |decision|
    case decision
    when String
      tags ||= {}
      tags[Tracing::Metadata::Ext::Distributed::TAG_DECISION_MAKER] = decision
    when :drop
      tags.delete(Tracing::Metadata::Ext::Distributed::TAG_DECISION_MAKER) if tags
    end
  end

  tags ||= {}
  tags[Tracing::Metadata::Ext::Distributed::TAG_DD_PARENT_ID] =
    ts_parent_id || Tracing::Metadata::Ext::Distributed::DD_PARENT_ID_DEFAULT

  TraceDigest.new(
    span_id: parent_id,
    trace_id: trace_id,
    trace_origin: origin,
    trace_sampling_priority: sampling_priority,
    trace_distributed_tags: tags,
    trace_flags: trace_flags,
    trace_state: tracestate,
    trace_state_unknown_fields: unknown_fields,
    span_remote: true,
  )
end

#inject!(digest, data) ⇒ Object 



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# File 'lib/datadog/tracing/distributed/trace_context.rb', line 24

def inject!(digest, data)
  return if digest.nil?

  if (traceparent = build_traceparent(digest))
    data[@traceparent_key] = traceparent

    if (tracestate = build_tracestate(digest))
      data[@tracestate_key] = tracestate
    end
  end

  data
end