Module: Datadog::Distributed

Defined in:
lib/ddtrace/distributed.rb

Overview

Common code related to distributed tracing.

Class Method Summary collapse

Class Method Details

.parse_trace_headers(trace_id_header, parent_id_header) ⇒ Object

Parses a trace_id and a parent_id, typically sent as headers in a distributed tracing context, and returns a couple of trace_id,parent_id which are garanteed to be both non-zero. This does not 100% ensure they are valid (after all, the caller could mess up data) but at least it sorts out most common errors, such as syntax, nil values, etc. Both headers must be set, else nil values are returned, for both. Reports problem on debug log.



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# File 'lib/ddtrace/distributed.rb', line 15

def parse_trace_headers(trace_id_header, parent_id_header)
  return nil, nil if trace_id_header.nil? || parent_id_header.nil?
  trace_id = trace_id_header.to_i
  parent_id = parent_id_header.to_i
  if trace_id.zero?
    Datadog::Tracer.log.debug("invalid trace_id header: #{trace_id_header}")
    return nil, nil
  end
  if parent_id.zero?
    Datadog::Tracer.log.debug("invalid parent_id header: #{parent_id_header}")
    return nil, nil
  end
  if trace_id < 0 || trace_id >= Datadog::Span::MAX_ID
    Datadog::Tracer.log.debug("trace_id out of range: #{trace_id_header}")
    return nil, nil
  end
  if parent_id < 0 || parent_id >= Datadog::Span::MAX_ID
    Datadog::Tracer.log.debug("parent_id out of range: #{parent_id_header}")
    return nil, nil
  end
  [trace_id, parent_id]
end