(PECL memcached >= 0.1.0)
Memcached::replace — Replace the item under an existing key
Memcached::replace() is similar to
Memcached::set(), but the operation fails if the
key does not exist on the server.
key
The key under which to store the value.
value
The value to store.
expiration
The expiration time, defaults to 0. See Expiration Times for more info.
Returns TRUE on success or FALSE on failure.
The Memcached::getResultCode() will return
Memcached::RES_NOTSTORED if the key does not exist.