Don't cache failed results for three weeks

by default if the shorten fails it gets cached for three weeks. This is bad. 10 mins is a more reasonable time to cache a failed url.

Fortunately the hook_shorten_create() can be used to work round this.

/* hook shorten_create */
/* Force a short cache on failed shorten attempts */
function my_module_shorten_create($orig,$url,$service) {
  if ($url != $orig) { return; }
  $expire = time() + 600;   //10 mins
  cache_set($orig, $url, 'cache', $expire);
}