readme.txt

Simple fragment caching helper for Sinatra
Created byBryan Thompson - bryan@radiowebservices.com - twitter.com/bryanthompson

Helper structure can probably be simplified, but I'm leaving space 
for future improvements like memcache and other settings that I 
might be overlooking right now

Actual caching scheme strongly inspired by merb and rails caching
methods.

Usage:

* drop cache_helper in a lib/ dir and require it
* set CACHE_ROOT 

<% cache "name_of_cache", :max_age => 60 do %>
  ... Stuff you want cached ...
<% end %>

For now, .cache files are dumped right into a tmp directory.  
defined as CACHE_ROOT.  I set mine in my site.rb file as
CACHE_ROOT = File.dirname(__FILE__)


=====================================================================================
Usage changes
=====================================================================================

* define the :cache_path setting on your application (set :cache_path, File.join(settings.root, 'tmp/cache'))

<% fragment_cache :foobar, 60 do %>
  ... Stuff you want cached ...
<% end %>

cache_helper.rb

require 'sinatra/base'

module Sinatra
  module FragmentCache
    def fragment_cache(name, age, &block)
      if cache = read_fragment(name, age)
        @_out_buf << cache
      else
        pos = @_out_buf.length
        tmp = block.call
        write_fragment(name, tmp[pos..-1])
      end
    end

    private
      def read_fragment(name, age)
        cache_file = File.join(settings.cache_path, "#{name}.cache")
        now = Time.now

        if File.exist?(cache_file)
          current_age = (now - File.mtime(cache_file)) / 60
          logger.info("Fragment for '#{name}' is #{current_age} minutes old.")

          return false if current_age > age
          return File.read(cache_file)
        end

        false
      end

      def write_fragment(name, buf)
        cache_file = File.join(settings.cache_path, "#{name}.cache")

        f = File.new(cache_file, 'w+')
        f.write(buf)
        f.close
        logger.info("Fragment written for '#{name}'")

        buf
      end
  end

  helpers FragmentCache
end