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 and retrying after any exception
#
#     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 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 = {})
  begin
    return yield if ((max_retries -= 1) > 0)
  rescue (options[:rescue_only] || Exception)
    options[:wait] *= options[:patience] if options[:patience]
    sleep(options[:wait] || 0)
    retry
  end
  yield
end

retry_upto_with_lambda_patience.rb

A variant that allows to pass a lambda as a patience factor, instead of an integer multiplier.
Allows for more complex cases, although maybe totally unneeded.

##########
def retry_upto(max_retries = 1, options = {})
  begin
    return yield if ((max_retries -= 1) > 0)
  rescue (options[:rescue_only] || Exception)
    options[:wait] = options[:patience].call(options[:wait]) if options[:patience] && options[:wait]
    sleep(options[:wait] || 0)
    retry
  end
  yield
end
##########

Example:

retry_upto(10, :wait => 2, :patience => lambda {|x| x*x}) do
  puts 1 / 0
end

retry_upto(10, :wait => 2, :patience => lambda {|x| Math.sqrt(x)}) do
  puts 1 / 0
end