dalliでもdelete_matchedが使えるようにする

dalli_delete_matched.rb

# fork
# https://github.com/Phobos98/dalli-delete-matched
# rails4環境だとエラー出たので以下のように修正した

ActiveSupport::Cache::DalliStore.class_eval do

  MEMCACHED_KEYS = 'memcached_keys'

  alias_method :old_write, :write
  def write(key, entry, options = nil)
    keys = get_memcached_keys
    unless keys.include?(key)
      keys << key
      return false unless old_write(MEMCACHED_KEYS, keys.to_yaml, {})
    end
    old_write(key, entry, options)
  end

  alias_method :old_delete, :delete
  def delete(key, options = nil)
    ret = old_delete(key, options)
    return false unless ret
    keys = get_memcached_keys
    if keys.include?(key)
      keys -= [ key ]
      old_write(MEMCACHED_KEYS, keys.to_yaml, {})
    end
    ret
  end

  def delete_matched(matcher, options = nil)
    ret = true
    deleted_keys = []
    keys = get_memcached_keys
    keys.each do |key|
      if ret && key.match(matcher)
        deleted_keys << key if (ret = old_delete(key, options))
      end
    end
    len = keys.length
    keys -= deleted_keys
    old_write(MEMCACHED_KEYS, keys.to_yaml, {}) if keys.length < len
    ret
  end

  private
    def get_memcached_keys
      begin
        YAML.load read(MEMCACHED_KEYS)
      rescue TypeError
        []
      end
    end

end