Memcached::isPristine

How is the return value determined? What is the definition of 'recently'? Does this function return true if the item was stored using the current connection?

From the source code of contructor, the "recently" means the connection to server of the instence is recently created, that is the instance was created without a persistent_id parameter or the first to use the persistent_id.

For instance, the guives a bool(true):

$memcached = new Memcached();
$isPristine = $memcached->isPristine();
var_dump($isPristine);

This also guives a bool(true):

$memcached = new Memcached('pid1');
$isPristine = $memcached->isPristine();
var_dump($isPristine);

while this guives a bool(false):

$memcached = new Memcached('pid1');
$memcached2 = new Memcached('pid1');
$isPristine = $memcached2->isPristine();
var_dump($isPristine);