Class: Datadog::Tracing::Contrib::MongoDB::MongoCommandSubscriber

Inherits:
Object
  • Object
show all
Defined in:
lib/datadog/tracing/contrib/mongodb/subscribers.rb

Overview

‘MongoCommandSubscriber` listens to all events from the `Monitoring` system available in the Mongo driver.

Instance Method Summary collapse

Instance Method Details

#failed(event) ⇒ Object

rubocop:enable Metrics/AbcSize

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# File 'lib/datadog/tracing/contrib/mongodb/subscribers.rb', line 78

def failed(event)
  span = get_span(event)
  return unless span

  # the failure is not a real exception because it's handled by
  # the framework itself, so we set only the error and the message
  span.set_error(event)
rescue StandardError => e
  Datadog.logger.debug("error when handling MongoDB 'failed' event: #{e}")
ensure
  # whatever happens, the Span must be removed from the local storage and
  # it must be finished to prevent any leak
  span.finish unless span.nil?
  clear_span(event)
end

#started(event) ⇒ Object

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# File 'lib/datadog/tracing/contrib/mongodb/subscribers.rb', line 17

def started(event)
  return unless Tracing.enabled?

  service = Datadog.configuration_for(event.address, :service_name) \
            || Datadog.configuration.tracing[:mongo, event.address.seed][:service_name]

  # start a trace and store it in the current thread; using the `operation_id`
  # is safe since it's a unique id used to link events together. Also only one
  # thread is involved in this execution so thread-local storage should be safe. Reference:
  # https://github.com/mongodb/mongo-ruby-driver/blob/master/lib/mongo/monitoring.rb#L70
  # https://github.com/mongodb/mongo-ruby-driver/blob/master/lib/mongo/monitoring/publishable.rb#L38-L56
  span = Tracing.trace(Ext::SPAN_COMMAND, service: service, type: Ext::SPAN_TYPE_COMMAND)
  set_span(event, span)

  # build a quantized Query using the Parser module
  query = MongoDB.query_builder(event.command_name, event.database_name, event.command)
  serialized_query = query.to_s

  if datadog_configuration[:peer_service]
    span.set_tag(
      Tracing::Metadata::Ext::TAG_PEER_SERVICE,
      datadog_configuration[:peer_service]
    )
  end

  # Tag original global service name if not used
  if span.service != Datadog.configuration.service
    span.set_tag(Tracing::Contrib::Ext::Metadata::TAG_BASE_SERVICE, Datadog.configuration.service)
  end

  span.set_tag(Contrib::Ext::DB::TAG_SYSTEM, Ext::TAG_SYSTEM)

  span.set_tag(Tracing::Metadata::Ext::TAG_KIND, Tracing::Metadata::Ext::SpanKind::TAG_CLIENT)

  span.set_tag(Tracing::Metadata::Ext::TAG_COMPONENT, Ext::TAG_COMPONENT)
  span.set_tag(Tracing::Metadata::Ext::TAG_OPERATION, Ext::TAG_OPERATION_COMMAND)

  span.set_tag(Tracing::Metadata::Ext::TAG_PEER_HOSTNAME, event.address.host)

  # Set analytics sample rate
  Contrib::Analytics.set_sample_rate(span, analytics_sample_rate) if analytics_enabled?

  # add operation tags; the full query is stored and used as a resource,
  # since it has been quantized and reduced
  span.set_tag(Ext::TAG_DB, query['database'])
  span.set_tag(Ext::TAG_COLLECTION, query['collection'])
  span.set_tag(Ext::DB::TAG_COLLECTION, query['collection'])
  span.set_tag(Ext::TAG_OPERATION, query['operation'])
  span.set_tag(Ext::TAG_QUERY, serialized_query)
  span.set_tag(Tracing::Metadata::Ext::NET::TAG_TARGET_HOST, event.address.host)
  span.set_tag(Tracing::Metadata::Ext::NET::TAG_TARGET_PORT, event.address.port)

  Contrib::SpanAttributeSchema.set_peer_service!(span, Ext::PEER_SERVICE_SOURCES)

  # set the resource with the quantized query
  span.resource = serialized_query
rescue StandardError => e
  Datadog.logger.debug("error when handling MongoDB 'started' event: #{e}")
end

#succeeded(event) ⇒ Object

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# File 'lib/datadog/tracing/contrib/mongodb/subscribers.rb', line 94

def succeeded(event)
  span = get_span(event)
  return unless span

  # add fields that are available only after executing the query
  rows = event.reply.fetch('n', nil)
  span.set_tag(Ext::TAG_ROWS, rows) unless rows.nil?
rescue StandardError => e
  Datadog.logger.debug("error when handling MongoDB 'succeeded' event: #{e}")
ensure
  # whatever happens, the Span must be removed from the local storage and
  # it must be finished to prevent any leak
  span.finish unless span.nil?
  clear_span(event)
end