src/ruby/lib/grpc/logconfig.rb

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# GRPC contains the General RPC module.
module GRPC
  # DefaultLogger is a module included in GRPC if no other logging is set up for
  # it.  See ../spec/spec_helpers an example of where other logging is added.
  module DefaultLogger
    def logger
      LOGGER
    end

    private

    # NoopLogger implements the methods of Ruby's conventional logging interface
    # that are actually used internally within gRPC with a noop implementation.
    class NoopLogger
      def info(_ignored)
      end

      def debug(_ignored)
      end

      def warn(_ignored)
      end
    end

    LOGGER = NoopLogger.new
  end

  # Inject the noop #logger if no module-level logger method has been injected.
  extend DefaultLogger unless methods.include?(:logger)
end