Patch the NewRelic RPM agent to allow for use of Fibers

newrelic-fiber-hack.rb

require 'new_relic/control'

# monkey-patch NewRelic::Agent::TransactionSampler to avoid storing the
# current TransactionSampleBuilder in a Thread-local, as it does not play nicely
# in the presence of Fibers

module NewRelic
  module Agent

    class TransactionSampler

      ACTIVE_BUILDERS = {}

      # Checks to see if the transaction sampler is disabled, if
      # transaction trace recording is disabled by a thread local, or
      # if execution is untraced - if so it clears the transaction
      # sample builder from the thread local, otherwise it generates a
      # new transaction sample builder with the stated time as a
      # starting point and saves it in the thread local variable
      def start_builder(time=nil)
        if disabled || !NewRelic::Agent.is_transaction_traced? || !NewRelic::Agent.is_execution_traced?
          clear_builder
        else
          ACTIVE_BUILDERS[Thread::current] ||= TransactionSampleBuilder.new(time)
        end
      end

      # The current thread-local transaction sample builder
      def builder
        ACTIVE_BUILDERS[Thread::current]
      end

      # Sets the thread local variable storing the transaction sample
      # builder to nil to clear it
      def clear_builder
        ACTIVE_BUILDERS[Thread::current] = nil
      end

    end

  end
end