Method: Datadog::Tracer#start_span

Defined in:
lib/ddtrace/tracer.rb

#start_span(name, options = {}) ⇒ Object

Return a span that will trace an operation called name. This method allows parenting passing child_of as an option. If it’s missing, the newly created span is a root span. Available options are:

  • service: the service name for this span

  • resource: the resource this span refers, or name if it’s missing

  • span_type: the type of the span (such as http, db and so on)

  • child_of: a Span or a Context instance representing the parent for this span.

  • start_time: when the span actually starts (defaults to now)

  • tags: extra tags which should be added to the span.



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# File 'lib/ddtrace/tracer.rb', line 195

def start_span(name, options = {})
  start_time = options.fetch(:start_time, Time.now.utc)
  tags = options.fetch(:tags, {})

  opts = options.select do |k, _v|
    # Filter options, we want no side effects with unexpected args.
    # Plus, this documents the code (Ruby 2 named args would be better but we're Ruby 1.9 compatible)
    [:service, :resource, :span_type].include?(k)
  end

  ctx, parent = guess_context_and_parent(options)
  opts[:context] = ctx unless ctx.nil?

  span = Span.new(self, name, opts)
  if parent.nil?
    # root span
    @sampler.sample(span)
    span.set_tag('system.pid', Process.pid)
  else
    # child span
    span.parent = parent # sets service, trace_id, parent_id, sampled
  end
  tags.each { |k, v| span.set_tag(k, v) } unless tags.empty?
  @tags.each { |k, v| span.set_tag(k, v) } unless @tags.empty?
  span.start_time = start_time

  # this could at some point be optional (start_active_span vs start_manual_span)
  ctx.add_span(span) unless ctx.nil?

  span
end