acts_as_cached.rb

# -*- coding: utf-8 -*-
require 'digest/sha1'
require 'db_cache'

module ActsAsCached

  module ClassMethods
    def acts_as_cached(options = {})
      extend RecordCache
    end
  end

  module RecordCache
    def get_cache(key=nil, &block)
      return nil if key.nil?
      dkey = digest_key(key)
      if rs = autoload_missing_constants { DBCache.get(dkey) }
        return rs
      end
      if block_given?
        if rs = yield
          DBCache.set(dkey, rs)
          return rs
        end
      end
      return nil
    end

    def autoload_missing_constants
      begin
        yield
      rescue ArgumentError => error
        lazy_load ||= Hash.new { |hash, hash_key| hash[hash_key] = true; false }
        if error.to_s[/undefined class|referred/] && !lazy_load[error.to_s.split.last.sub(/::$/, '').constantize]
          retry
        else
          raise error
        end
      end
    end

    def set_cache(key, rs)
      return DBCache.set(digest_key(key), rs)
    end

    def expire_cache(key)
      return DBCache.delete(digest_key(key))
    end

    def digest_key(key)
      case key
        when Array
          key = key.flatten.join('-')
        else
          key = key.to_s unless key.is_a?(String)
      end
      return Digest::SHA1.hexdigest("#{cache_name}:#{key}")
    end

    def cache_name
      return respond_to?(:base_class) ? base_class.name : name
    end
  end
end

Object.send :extend, ActsAsCached::ClassMethods