trace_logger.rb

# Called by wrapping arbitrary code-to-be-logged in a block.  Its return value
# will be the return value of whatever's in the block. e.g.

# require '/Users/jack/lib/trace_logger'

# def my_method
#   ...
#   foo = some_buggy_method
#   ...
# end

# def my_method
#   ...
#   foo = tl { some_buggy_method }
#   ...
# end

module TraceLogger
  delegate :root, to: :Rails

  def tl
    raise(LocalJumpError, 'no block given (yield)') unless block_given?

    logger = Logger.new(root.join('log', "trace_#{object_id}.log"))

    trace_point =
      TracePoint.new(:call) do |it|
        payload = {
          file: it.path,
          line: it.lineno,
          method: it.method_id
        }.to_json

        logger.info(payload)
      end

    trace_point.enable
    block_call = yield
    trace_point.disable
    block_call
  end
end

Module.include(TraceLogger)