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 37

def failed(event)
  span = Thread.current[:datadog_mongo_span]
  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::Tracer.log.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?
  Thread.current[:datadog_mongo_span] = nil
end

#started(event) ⇒ Object 



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# File 'lib/ddtrace/contrib/mongodb/subscribers.rb', line 8

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('mongo.cmd', service: pin.service, span_type: Datadog::Ext::Mongo::TYPE)
  Thread.current[:datadog_mongo_span] = span

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

  # add operation tags; the full query is stored and used as a resource,
  # since it has been quantized and reduced
  span.set_tag(Datadog::Ext::Mongo::DB, query[:database])
  span.set_tag(Datadog::Ext::Mongo::COLLECTION, query[:collection])
  span.set_tag(Datadog::Ext::Mongo::OPERATION, query[:operation])
  span.set_tag(Datadog::Ext::Mongo::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 53

def succeeded(event)
  span = Thread.current[:datadog_mongo_span]
  return unless span

  # add fields that are available only after executing the query
  rows = event.reply.fetch('n', nil)
  span.set_tag(Datadog::Ext::Mongo::ROWS, rows) unless rows.nil?
rescue StandardError => e
  Datadog::Tracer.log.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?
  Thread.current[:datadog_mongo_span] = nil
end