Class: GRPC::OpenTracing::ServerInterceptor

Inherits:
Object
  • Object
show all
Defined in:
lib/grpc/opentracing/server_interceptor.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tracer: ::OpenTracing.global_tracer, decorators: [RequestReplySpanDecorator]) ⇒ ServerInterceptor

Returns a new instance of ServerInterceptor.



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# File 'lib/grpc/opentracing/server_interceptor.rb', line 6

def initialize(tracer: ::OpenTracing.global_tracer, decorators: [RequestReplySpanDecorator])
  @tracer = tracer
  @decorators = decorators
end

Instance Attribute Details

#decorators ⇒ Object (readonly)

Returns the value of attribute decorators.



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# File 'lib/grpc/opentracing/server_interceptor.rb', line 4

def decorators
  @decorators
end

#tracer ⇒ Object (readonly)

Returns the value of attribute tracer.



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# File 'lib/grpc/opentracing/server_interceptor.rb', line 4

def tracer
  @tracer
end

Instance Method Details

#intercept(service) ⇒ Object 



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# File 'lib/grpc/opentracing/server_interceptor.rb', line 11

def intercept(service)
  service_class = service.is_a?(Class) ? service : service.class
  service_class.rpc_descs.each_pair do |name, desc|
    route = "/#{service_class.service_name}/#{name}".to_sym
    method_name = GRPC::GenericService.underscore(name.to_s).to_sym
    method_name_without_instrumentation = "#{method_name}_without_instrumentation".to_sym
    interceptor = self

    service_class.class_eval do
      @tracer = interceptor.tracer
      @decorators = interceptor.decorators

      class << self
        attr_reader :tracer, :decorators
      end

      def tracer
        self.class.tracer
      end

      def decorators
        self.class.decorators
      end
    end

    if desc.request_response?
      service_class.class_eval do
        if method_defined?(method_name_without_instrumentation)
          alias_method method_name, method_name_without_instrumentation
          remove_method method_name_without_instrumentation
        end

        alias_method method_name_without_instrumentation, method_name

        define_method(method_name) do |req, active_call|
          begin
            tags = {
              'component' => 'gRPC',
              'span.kind' => 'server',
              'grpc.method_type' => 'request_response'
            }
            hpack_carrier = HPACKCarrier.new(active_call.metadata)
            parent_span_context = tracer.extract(::OpenTracing::FORMAT_TEXT_MAP, hpack_carrier)
            current_span = tracer.start_span(route.to_s, child_of: parent_span_context, tags: tags)

            response = self.send(method_name_without_instrumentation, req, active_call)

            response
          rescue Exception => e
            if current_span
              current_span.set_tag('error', true)
              current_span.log(event: 'error', :'error.object' => e)
            end
            raise
          ensure
            if decorators
              decorators.each do |decorator|
                decorator.call(current_span, route, req, response, e)
              end
            end
            current_span.finish if current_span
          end
        end
      end
    end
  end

  service
end