This operation fails (returns false) if the key already exists in cache.
If the operation succeeds, true will be returned.
| public add ( string $key, mixed $value, integer $expire ) : boolean | ||
| $key | string | |
| $value | mixed | |
| $expire | integer | Time when item falls out of the cache: 0 = permanent (doesn't expires); under 2592000 (30 days) = relative time, in seconds from now; over 2592000 = absolute time, unix timestamp |
| return | boolean | |
/**
* As soon as a key turns up empty (doesn't yet exist in cache), we'll
* "protect" it for some time. This will be done by writing to a key similar
* to the original key name. If this key is present (which it will only be
* for a short amount of time) we'll know it's protected.
*
* @param array $keys
*
* @return string[] Array of keys that were successfully protected
*/
protected function protect(array $keys)
{
if (empty($keys)) {
return array();
}
$success = array();
foreach ($keys as $key) {
/*
* Key is add()ed because there may be multiple concurrent processes
* that are both in the process of protecting - first one to add()
* wins (and those are returned by the function, so those that are
* failed to protect can be considered protected)
*/
$success[$key] = $this->cache->add($this->stampedeKey($key), '', $this->sla);
}
return array_keys(array_filter($success));
}