retriable.rb

class Retriable

  class << self
    def config(&block)
      self.new(&block)
    end
  end

  def initialize(&block)
    max_attempts 5
    retry_if { true }
    backoff { 1 }

    if block_given?
      instance_eval(&block)
    end
  end

  def max_attempts(value=nil)
    if value.nil?
      @max_attempts
    else
      @max_attempts = value
      self
    end
  end

  def retry_if(&block)
    if block_given?
      @retry_if = block
      self
    else
      @retry_if
    end
  end

  def backoff(&block)
    if block_given?
      @backoff = block
      self
    else
      @backoff
    end
  end

  def execute(&block)
    attempts = 0
    begin
      attempts += 1
      if block.arity == 1
        yield(attempts-1)
      else
        yield
      end
    rescue => e
      if attempts < max_attempts && should_retry?(e)
        sleep(compute_backoff(attempts))
        retry
      else
        raise e
      end
    end
  end

  private

    def should_retry?(e)
      @retry_if ? true : @retry_if.call(e)
    end

    def compute_backoff(attempts)
      if @backoff.kind_of?(Proc)
        @backoff.arity == 1 ? @backoff.call(attempts) : @backoff.call
      else
        0
      end
    end
end

retriable_example.rb

r = Retriable.new {
  max_attempts 3
  retry_if {|e| e.kind_of?(DownError) }
  backoff {|attempt| (attempt*0.5) + rand(1000)/1000.0 }
}

client = SomeClient.new
result = r.execute {
  client.get_stuff
}