retry_upto.rb

retry_upto.rb

# Ruby `retry` with steroids:
#
# - retry up to 5 times without waiting between them and retrying after any exception
#
#     retry_upto(5) do ... end
#
# - retry up to 5 times, waiting 2 seconds between retries
#
#     retry_upto(5, :wait => 2) do ... end
#
# - retry up to 5 times, waiting 1 second initially and having increasing patience (2, 4, 8, ...)
#
#     retry_upto(5, :wait => 1, :patience => 2) do ... end
#
# - retry up to 5 times, waiting 1 second initially and having decreasing patience (0.5, 0.25, 0.125, ...)
#
#     retry_upto(5, :wait => 1, :patience => 0.5) do ... end
#
# - retry up to 5 times, waiting 1 second initially and retrying with a randomly increasing patience
#
#     retry_upto(5, :wait => 1, :patience => lambda{ |x| x + rand(3) } ) do ... end
#
# - retry up to 5 times without waiting between retries, retrying only after a ZeroDivisionError
#
#     retry_upto(5, :rescue_only => ZeroDivisionError) do ... end
#
# - retry up to 5 times, waiting 2 seconds between retries, retrying only after a ZeroDivisionError
#
#     retry_upto(5, :wait => 2, :rescue_only => ZeroDivisionError) do ... end
#

def retry_upto(max_retries = 1, options = {})
  yield
rescue (options[:rescue_only] || Exception)
  raise if (max_retries -= 1) == 0
  if options[:patience].respond_to?('*')
    options[:wait] = options[:wait] * options[:patience]
  elsif options[:patience].respond_to?(:call)
    options[:wait] = options[:patience].call(options[:wait])
  end
  sleep(options[:wait] || 0)
  retry
end


# Extends enumerator to allow usage like:
#
#    5.times.retry do
#      ...
#    end
#

class Enumerator
  def retry(options = {}, &blk)
    retry_upto(self.count, options, &blk)
  end
end

It's taking a way better shape thanks to @ped and @glenngillen!!!

Added :patience feature as I've seen this use case several times too, thanks @jaimeiniesta!

Code compacted by @lleirborras, thanks man!

I usually like to implement Object#first_you_respond_to(*methods) in my apps

Using it my implementation of retry_upto would be:

def retry_upto(max_retries = 1, opts = {})
yield
rescue (opts[:rescue_only] || Exception)
raise if (max_retries -= 1) == 0
if opts[:wait]
meth = opts[:patience].first_you_respond_to(:*, :call)
opts[:wait] = opts[:patience].send(meth, opts[:wait]) if meth
sleep opts[:wait]
end
retry
end

Hope you like it!

Sounds nice, though I'd prefer to keep this without external dependencies. I've finally published it as a gem: http://github.com/raul/retry_upto