class OneApm::Support::TracedMethodStack

TracedMethodStack is responsible for tracking the push and pop of methods that we are tracing, notifying the transaction sampler, and calculating exclusive time when a method is complete. This is allowed whether a transaction is in progress not.

Public Class Methods

new() click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 25
def initialize
  @stack = []
end

Public Instance Methods

clear() click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 93
def clear
  @stack.clear
end
empty?() click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 97
def empty?
  @stack.empty?
end
fetch_matching_frame(expected_frame) click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 60
def fetch_matching_frame(expected_frame)
  while frame = @stack.pop
    if frame == expected_frame
      return frame
    else
      OneApm::Manager.logger.info("Unexpected frame in traced method stack: #{frame.inspect} expected to be #{expected_frame.inspect}")
      OneApm::Manager.logger.debug do
        ["Backtrace for unexpected frame: ", caller.join("\n")]
      end
    end
  end

  raise "Frame not found in blame stack: #{expected_frame.inspect}"
end
note_children_time(frame, time, deduct_call_time_from_parent) click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 75
def note_children_time(frame, time, deduct_call_time_from_parent)
  if !@stack.empty?
    if deduct_call_time_from_parent
      @stack.last.children_time += (time - frame.start_time)
    else
      @stack.last.children_time += frame.children_time
    end
  end
end
pop_frame(state, expected_frame, name, time, deduct_call_time_from_parent=true) click to toggle source

Pops a frame off the transaction stack - this updates the transaction sampler that we've finished execution of a traced method.

expected_frame should be TracedMethodFrame from the corresponding push_frame call.

name will be applied to the generated transaction trace segment.

# File lib/one_apm/support/traced_method_stack.rb, line 50
def pop_frame(state, expected_frame, name, time, deduct_call_time_from_parent=true)
  frame = fetch_matching_frame(expected_frame)

  note_children_time(frame, time, deduct_call_time_from_parent)

  transaction_sampler.notice_pop_frame(state, name, time) if sampler_enabled?
  frame.name = name
  frame
end
push_frame(state, tag, time = Time.now.to_f) click to toggle source

Pushes a frame onto the transaction stack - this generates a TransactionSample::Segment at the end of transaction execution.

The generated segment won't be named until pop_frame is called.

tag should be a Symbol, and is only for debugging purposes to identify this frame if the stack gets corrupted.

# File lib/one_apm/support/traced_method_stack.rb, line 36
def push_frame(state, tag, time = Time.now.to_f)
  transaction_sampler.notice_push_frame(state, time) if sampler_enabled?
  frame = TracedMethodFrame.new(tag, time)
  @stack.push frame
  frame
end
sampler_enabled?() click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 85
def sampler_enabled?
  OneApm::Manager.config[:'transaction_tracer.enabled']
end
transaction_sampler() click to toggle source
# File lib/one_apm/support/traced_method_stack.rb, line 89
def transaction_sampler
  OneApm::Manager.agent.transaction_sampler
end