A rake task to geocode all objects of a particular class using the Ruby Geocoder gem, retrying 3 times if unsuccessful. This is primarily targetted at the Google Maps API which limits the number of requests per second. By building in an increasing back off before each retry we can ensure we recover from these temporary bans.

geocoder.rake

namespace :geocoder do
  desc "Geocode all objects without coordinates."
  task :all_with_retry => :environment do
    class_name = ENV['CLASS'] || ENV['class']
    sleep_timer = ENV['SLEEP'] || ENV['sleep']
    raise "Please specify a CLASS (model)" unless class_name
    klass = class_from_string(class_name)

    klass.not_geocoded.each do |obj|
      geocode_with_retry obj
      sleep(sleep_timer.to_f) unless sleep_timer.nil?
    end
  end
end

def geocode_with_retry(obj)
  tries ||= 3
  puts "Trying again, #{tries} tries left..." if tries < 3
  puts Time.now.strftime("%Y%m%d%H%M%S")+": Geocoding " + obj.to_s
  obj.geocode
  if obj.geocoded?
    obj.save
  else
    sleep(3.0/tries) #Back off in 1s, 2s, 3s intervals
    raise Geocoder::OverQueryLimitError
  end 
  rescue Geocoder::OverQueryLimitError => e
    retry unless (tries -= 1).zero?
end

##
# Get a class object from the string given in the shell environment.
# Similar to ActiveSupport's +constantize+ method.
#
def class_from_string(class_name)
  parts = class_name.split("::")
  constant = Object
  parts.each do |part|
    constant = constant.const_get(part)
  end
  constant
end

Usage

rake geocoder:all_with_retry CLASS=Location SLEEP=0.25

Based on https://github.com/alexreisner/geocoder/blob/master/lib/tasks/geocoder.rake