fiber.rb

require 'fiber'
# Call create to get a new fiber
class ReaderProcessor

  def self.create(notifier)
    Fiber.new do
      while notifier.no_data_yet do
        puts "Reader has no data yet"
        Fiber.yield
      end
      puts "Reader has data!"
      puts "Reader did some work on data!"
    end
  end

end

class WriterProcessor
  def self.create(notifier)
    Fiber.new do
      notifier.set_data
      puts "Writer created data!"
    end
  end
end

class RootFiber
  @@n_fibers = 10

  def initialize args
    @notifier = args[:notifier]
    @fibers = []
    @fibers << ReaderProcessor.create(@notifier)
    @fibers << WriterProcessor.create(@notifier)
  end

  # returns true if a fiber was executed
  def try
    ran = false
    @fibers.each do |fiber|
      if fiber.alive?
        ran = true
        fiber.resume
      end
    end
    ran
  end

  def run
    while try do
      try
    end
  end
end

class Notifier
  def initialize
    @data = false
  end

  def set_data
    @data = true
  end

  def no_data_yet
    true if @data == false
  end
end

def main
  puts "Before new"

  rf = RootFiber.new notifier: Notifier.new
  rf.run
end

main()