Retry Proxy

retry_proxy.rb

class RetryProxy < BasicObject

  def initialize target, retries, logger=nil
    @target  = target
    @retries = retries
    @logger  = logger
  end

  BasicObject.instance_methods.each do |basic_object_instance_method|
    define_method(basic_object_instance_method) do |*args, &block|
      @target.send(basic_object_instance_method, *args, &block)
    end
  end

  def method_missing symbol, *args, &block
    retries = @retries
    begin
      @target.send(symbol, *args, &block)
    rescue
      retries -= 1
      ::Kernel.raise $! if retries == 0
      message = "While calling #{@target.to_s} (#{@target.class}) received exception, will retry: #{$!} (#{$!.class})"
      @logger.warn(message) if @logger
      retry
    end
  end

end

class FailOnce
  def initialize
    @fail = true
  end

  def fail
    if @fail
      @fail = false
      raise "Fail at first!"
    else
      "Now it works!"
    end
  end

  def == other
    true
  end
end

require 'logger'
target = FailOnce.new
proxy_target = RetryProxy.new(target, 3, Logger.new(STDOUT))
p(proxy_target.fail)
# BasicObject instance methods are also delegated
p(proxy_target == 3)

# >> W, [2016-08-23T13:54:37.259614 #25557]  WARN -- : While calling #<FailOnce:0x007fcfe39d5778> (FailOnce) received exception, will retry: Fail at first! (RuntimeError)
# >> "Now it works!"
# >> true