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

Inherits:
Object
  • Object
show all
Defined in:
lib/ddtrace/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 



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# File 'lib/ddtrace/contrib/mongodb/subscribers.rb', line 48

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/ddtrace/contrib/mongodb/subscribers.rb', line 13

def started(event)
  pin = Datadog::Pin.get_from(event.address)
  return unless pin && pin.enabled?

  # 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 = pin.tracer.trace(Ext::SPAN_COMMAND, service: pin.service, span_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

  # Tag as an external peer service
  span.set_tag(Datadog::Ext::Integration::TAG_PEER_SERVICE, span.service)

  # 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::TAG_OPERATION, query['operation'])
  span.set_tag(Ext::TAG_QUERY, serialized_query)
  span.set_tag(Datadog::Ext::NET::TARGET_HOST, event.address.host)
  span.set_tag(Datadog::Ext::NET::TARGET_PORT, event.address.port)

  # set the resource with the quantized query
  span.resource = serialized_query
end

#succeeded(event) ⇒ Object 



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# File 'lib/ddtrace/contrib/mongodb/subscribers.rb', line 64

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