A monkeypatch to Rails' ActionView::Helpers::TextHelper (or that class provided by the rails_autolink gem) which causes it to chop up input data in case it's too long to handle

actionview_helpers_texthelper_autolink_patch.rb

# encoding: utf-8

# Patch for auto_link method to chop text up into lines first,
# speeding up its run time considerably and making it resilient to bad or overly gigantic input

if defined?(ActionView::Helpers::TextHelper) && ActionView::Helpers::TextHelper.instance_methods.include?(:auto_link)
  module ActionView
    module Helpers
      module TextHelper
        unless defined?(slow_auto_link) # we don't want to method chain it twice...

          MAX_LINE_LENGTH = 500 # characters

          alias_method :slow_auto_link, :auto_link
          # Redefine auto_link to split its text by lines first
          # and then run the original auto_link against those lines
          def auto_link(text, *args, &block)
            words = []

            text.split("\n").map! do |line|
              # I'm worried about the line being too long still, catastrophic case of no line breaks
              # so I am further splitting into groups of words on spaces.
              # In the catastrophic case of no spaces either... Well then we're
              # stuck as splitting randomly could chop up URL's, so I just return the original string.
              if line.length > MAX_LINE_LENGTH
                # Try to split into groups of 30 words if the line is too long.
                # note: splitting on \s here instead of ' ' for a reason- the latter does not preserve runs of spaces
                words_grouped = line.split(/\s/).each_slice(30).to_a.map!{|wg| wg.join(' ')}
                words_grouped.map! do |words|
                  if words.length > MAX_LINE_LENGTH
                    words # just give up and choke out the original text
                  else
                    slow_auto_link(words, *args, &block)
                  end
                end.join(' ')
              else
                slow_auto_link(line, *args, &block)
              end
            end.join("\n")

          end # new auto_link
        else
          msg = "WARNING: Attempt to alias auto_link to slow_auto_link when slow_auto_link is already defined, in #{__FILE__}"
          puts msg
          Rails.logger.warn msg
        end # redefining slow_auto_link check
      end # TextHelper
    end # Helpers
  end # ActionView
else
  raise "Can't monkeypatch ActionView::Helpers::TextHelper#auto_link unless the class exists first and the method is already defined, perhaps via the rails_autolink gem if this is Rails.version >= 3.1"
end