func (self *LazyCacheController) invalidateBoardPage(group string, pageno int) {
key := util.GetFilenameForBoardPage(self.webroot_dir, group, pageno, false)
self.c.DeleteCache(key)
}
// regenerate just a page on a board
func (self *LazyCacheController) regenerateBoardPage(board string, page int) {
key := util.GetFilenameForBoardPage(self.webroot_dir, board, page, false)
self.c.Cache(key, self.regen.GenerateBoardPage(board, page))
}