Class: Datadog::OpenTracer::Tracer

Inherits:
OpenTracing::Tracer
  • Object
show all
Defined in:
lib/datadog/opentracer/tracer.rb

Overview

OpenTracing adapter for Datadog::Tracer

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(**options) ⇒ Tracer

Returns a new instance of Tracer.



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# File 'lib/datadog/opentracer/tracer.rb', line 17

def initialize(**options)
  super()
  @datadog_tracer = Datadog::Tracing::Tracer.new(**options)
end

Instance Attribute Details

#datadog_tracer ⇒ Datadog::Tracer (readonly)

Returns:

  • (Datadog::Tracer) 


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# File 'lib/datadog/opentracer/tracer.rb', line 13

def datadog_tracer
  @datadog_tracer
end

Instance Method Details

#extract(format, carrier) ⇒ SpanContext?

Extract a SpanContext in the given format from the given carrier.

Parameters:

  • format (OpenTracing::FORMAT_TEXT_MAP, OpenTracing::FORMAT_BINARY, OpenTracing::FORMAT_RACK)
  • carrier (Carrier) —

    A carrier object of the type dictated by the specified ‘format`

Returns:

  • (SpanContext, nil) —

    the extracted SpanContext or nil if none could be found



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# File 'lib/datadog/opentracer/tracer.rb', line 184

def extract(format, carrier)
  case format
  when OpenTracing::FORMAT_TEXT_MAP
    TextMapPropagator.extract(carrier)
  when OpenTracing::FORMAT_BINARY
    BinaryPropagator.extract(carrier)
  when OpenTracing::FORMAT_RACK
    RackPropagator.extract(carrier)
  else
    warn 'Unknown extract format'
    nil
  end
end

#inject(span_context, format, carrier) ⇒ Object

Inject a SpanContext into the given carrier.

Parameters:

  • span_context (SpanContext)
  • format (OpenTracing::FORMAT_TEXT_MAP, OpenTracing::FORMAT_BINARY, OpenTracing::FORMAT_RACK)
  • carrier (Carrier) —

    A carrier object of the type dictated by the specified ‘format`



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# File 'lib/datadog/opentracer/tracer.rb', line 166

def inject(span_context, format, carrier)
  case format
  when OpenTracing::FORMAT_TEXT_MAP
    TextMapPropagator.inject(span_context, carrier)
  when OpenTracing::FORMAT_BINARY
    BinaryPropagator.inject(span_context, carrier)
  when OpenTracing::FORMAT_RACK
    RackPropagator.inject(span_context, carrier)
  else
    warn 'Unknown inject format'
  end
end

#scope_manager ⇒ ScopeManager

Returns the current ScopeManager.

Returns:



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# File 'lib/datadog/opentracer/tracer.rb', line 23

def scope_manager
  @scope_manager ||= ThreadLocalScopeManager.new
end

#start_active_span(operation_name, child_of: nil, references: nil, start_time: Time.now, tags: nil, ignore_active_scope: false, finish_on_close: true) {|Scope| ... } ⇒ Scope

Returns a newly started and activated Scope.

If ‘scope_manager.active` is not nil, no explicit references are provided, and `ignore_active_scope` is false, then an inferred OpenTracing::Reference#CHILD_OF reference is created to the `scope_manager.active`’s SpanContext when #start_active_span is invoked.

Parameters:

  • operation_name (String) —

    The operation name for the Span

  • child_of (SpanContext, Span) (defaults to: nil) —

    SpanContext that acts as a parent to the newly-started Span. If a Span instance is provided, its context is automatically substituted. See [OpenTracing::Reference] for more information. If specified, the ‘references` parameter must be omitted.

  • references (Array<OpenTracing::Reference>) (defaults to: nil) —

    An array of reference objects that identify one or more parent SpanContexts.

  • start_time (Time) (defaults to: Time.now) —

    When the Span started, if not now

  • tags (Hash) (defaults to: nil) —

    Tags to assign to the Span at start time

  • ignore_active_scope (Boolean) (defaults to: false) —

    whether to create an implicit OpenTracing::Reference#CHILD_OF reference to the ScopeManager#active.

  • finish_on_close (Boolean) (defaults to: true) —

    whether span should automatically be finished when Scope#close is called

Yields:

  • (Scope) —

    If an optional block is passed to start_active it will yield the newly-started Scope. If ‘finish_on_close` is true then the Span will be finished automatically after the block is executed.

Returns:

  • (Scope) —

    The newly-started and activated Scope



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# File 'lib/datadog/opentracer/tracer.rb', line 53

def start_active_span(
  operation_name,
  child_of: nil,
  references: nil,
  start_time: Time.now,
  tags: nil,
  ignore_active_scope: false,
  finish_on_close: true
)

  # When meant to automatically determine the parent,
  # Use the active scope first, otherwise fall back to any
  # context generated by Datadog, so as to append to it and gain
  # the benefit of any out-of-the-box tracing from Datadog preceding
  # the OpenTracer::Tracer.
  #
  # We do this here instead of in #start_span because #start_span generates
  # spans that are not assigned to a scope, a.k.a not supposed to be used by
  # subsequent spans implicitly. By using the existing Datadog context, the span
  # effectively ends up "assigned to a scope", by virtue of being added to the
  # Context. Hence, it would behave more like an active span, which is why it
  # should only be here.
  unless child_of || ignore_active_scope
    child_of = if scope_manager.active
                 scope_manager.active.span.context
               else
                 SpanContextFactory.build(datadog_context: datadog_tracer.send(:call_context))
               end
  end

  # Create the span, and auto-add it to the Datadog context.
  span = start_span(
    operation_name,
    child_of: child_of,
    references: references,
    start_time: start_time,
    tags: tags,
    ignore_active_scope: ignore_active_scope
  )

  # Overwrite the tracer context with the OpenTracing managed context.
  # This is mostly for the benefit of any out-of-the-box tracing from Datadog,
  # such that spans generated by that tracing will be attached to the OpenTracer
  # parent span.
  datadog_tracer.provider.context = span.context.datadog_context

  scope_manager.activate(span, finish_on_close: finish_on_close).tap do |scope|
    if block_given?
      begin
        yield(scope)
      ensure
        scope.close
      end
    end
  end
end

#start_span(operation_name, child_of: nil, references: nil, start_time: Time.now, tags: nil, ignore_active_scope: false) ⇒ Span

Like #start_active_span, but the returned Span has not been registered via the ScopeManager.

Parameters:

  • operation_name (String) —

    The operation name for the Span

  • child_of (SpanContext, Span) (defaults to: nil) —

    SpanContext that acts as a parent to the newly-started Span. If a Span instance is provided, its context is automatically substituted. See [Reference] for more information. If specified, the ‘references` parameter must be omitted.

  • references (Array<Reference>) (defaults to: nil) —

    An array of reference objects that identify one or more parent SpanContexts.

  • start_time (Time) (defaults to: Time.now) —

    When the Span started, if not now

  • tags (Hash) (defaults to: nil) —

    Tags to assign to the Span at start time

  • ignore_active_scope (Boolean) (defaults to: false) —

    whether to create an implicit References#CHILD_OF reference to the ScopeManager#active.

Returns:

  • (Span) —

    the newly-started Span instance, which has not been automatically registered via the ScopeManager



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# File 'lib/datadog/opentracer/tracer.rb', line 127

def start_span(
  operation_name,
  child_of: nil,
  references: nil,
  start_time: Time.now,
  tags: nil,
  ignore_active_scope: false
)

  # Derive the OpenTracer::SpanContext to inherit from.
  parent_span_context = inherited_span_context(child_of, ignore_active_scope: ignore_active_scope)

  # Retrieve Datadog::Context from parent SpanContext.
  datadog_context = parent_span_context.nil? ? Datadog::Tracing::Context.new : parent_span_context.datadog_context
  datadog_trace_digest = parent_span_context && parent_span_context.datadog_trace_digest

  # Build the new Datadog span
  datadog_span = datadog_tracer.trace(
    operation_name,
    continue_from: datadog_trace_digest,
    _context: datadog_context,
    start_time: start_time,
    tags: tags || {}
  )

  span_context = SpanContextFactory.build(
    datadog_context: datadog_context || datadog_tracer.send(:call_context),
    baggage: parent_span_context ? parent_span_context.baggage.dup : {}
  )

  # Wrap the Datadog span and OpenTracer::Span context in a OpenTracer::Span
  Span.new(datadog_span: datadog_span, span_context: span_context)
end