module NewRelic::Agent::Instrumentation::Curb::Multi
Constants
- INSTRUMENTATION_NAME
Public Instance Methods
Add CAT with callbacks if the request is serial
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 74 def add_with_tracing(curl) if curl.respond_to?(:_nr_serial) && curl._nr_serial hook_pending_request(curl) if NewRelic::Agent::Tracer.tracing_enabled? end return yield end
Instrument the specified request
(a Curl::Easy object) and set up cross-application tracing if it’s enabled.
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 95 def hook_pending_request(request) wrapped_request, wrapped_response = wrap_request(request) segment = NewRelic::Agent::Tracer.start_external_request_segment( library: wrapped_request.type, uri: wrapped_request.uri, procedure: wrapped_request.method ) segment.add_request_headers(wrapped_request) # install all callbacks unless request._nr_instrumented install_header_callback(request, wrapped_response) install_completion_callback(request, wrapped_response, segment) install_failure_callback(request, wrapped_response, segment) request._nr_instrumented = true end rescue => err NewRelic::Agent.logger.error('Untrapped exception', err) end
Install a callback that will finish the trace.
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 143 def install_completion_callback(request, wrapped_response, segment) original_callback = request.on_complete request._nr_original_on_complete = original_callback request.on_complete do |finished_request| begin segment&.process_response_headers(wrapped_response) ensure ::NewRelic::Agent::Transaction::Segment.finish(segment) # Make sure the existing completion callback is run, and restore the # on_complete callback to how it was before. original_callback&.call(finished_request) remove_instrumentation_callbacks(request) end end end
Install a callback that will fire on failures NOTE: on_failure is not always called, so we’re not always unhooking the callback. No harm/no foul in production, but definitely something to beware of if debugging callback issues @__newrelic_original_callback exists to prevent infinitely chaining our on_failure callback hook.
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 165 def install_failure_callback(request, _wrapped_response, segment) original_callback = request.on_failure nr_original_callback = original_callback.instance_variable_get(:@__newrelic_original_callback) original_callback = nr_original_callback || original_callback request._nr_original_on_failure = original_callback newrelic_callback = proc do |failed_request, error| begin if segment noticeable_error = NewRelic::Agent::NoticeableError.new(error[0].name, error[-1]) segment.notice_error(noticeable_error) end ensure original_callback&.call(failed_request, error) remove_failure_callback(failed_request) end end newrelic_callback.instance_variable_set(:@__newrelic_original_callback, original_callback) request.on_failure(&newrelic_callback) end
Install a callback that will record the response headers to enable CAT linking
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 128 def install_header_callback(request, wrapped_response) original_callback = request.on_header request._nr_original_on_header = original_callback request._nr_header_str = nil request.on_header do |header_data| if original_callback original_callback.call(header_data) else wrapped_response.append_header_data(header_data) header_data.length end end end
Trace as an External/Multiple call if the first request isn’t serial.
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 83 def perform_with_tracing return yield if first_request_is_serial? NewRelic::Agent.record_instrumentation_invocation(INSTRUMENTATION_NAME) trace_execution_scoped('External/Multiple/Curb::Multi/perform') do yield end end
We execute customer’s on_failure callback (if any) and uninstall our hook here since the on_complete callback fires before the on_failure callback.
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 201 def remove_failure_callback(request) request.on_failure(&request._nr_original_on_failure) end
on_failure callbacks cannot be removed in the on_complete callback where this method is invoked because on_complete fires before the on_failure!
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 192 def remove_instrumentation_callbacks(request) request.on_complete(&request._nr_original_on_complete) request.on_header(&request._nr_original_on_header) request._nr_instrumented = false end
Create request and response adapter objects for the specified request
NOTE: Although strange to wrap request and response at once, it works because curb’s callback mechanism updates the instantiated wrappers during the life-cycle of external request
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 121 def wrap_request(request) return NewRelic::Agent::HTTPClients::CurbRequest.new(request), NewRelic::Agent::HTTPClients::CurbResponse.new(request) end
Private Instance Methods
# File lib/new_relic/agent/instrumentation/curb/instrumentation.rb, line 207 def first_request_is_serial? return false unless (first = self.requests.first) # Before curb 0.9.8, requests was an array of Curl::Easy # instances. Starting with 0.9.8, it's a Hash where the # values are Curl::Easy instances. # # So, requests.first will either be an_obj or [a_key, an_obj]. # We need to handle either case. # first = first[-1] if first.is_a?(Array) first.respond_to?(:_nr_serial) && first._nr_serial end