Question

I am trying to store splqueue to memcache (NOT memcached). The following sample code is a simple test for this purpose.

$mc = new Memcache();
$mc->addServer("127.0.0.1", 11300);
$mc->addServer("127.0.0.1", 11301);
$mc->addServer("127.0.0.1", 11302);

$q = new SplQueue();
$q->enqueue(10);
$q->enqueue(20);
$q->count(); // line a

$mc->set("spl_queue", $q);
$p = $mc->get("spl_queue");
$p->count(); // line b

When I run this code, I got 2 in line a and 0 in line b. So it probably means storing data structure in memcache doesn’t work.

So I have following three questions.

1. Did I do anything wrong or there is another way to store splqueue in memcache?

2. I also found SplObjectStorage for Spl data structures. Can this be a solution for my problem?

3. Can memcached (NOT memcache) store data structures?

Answer 1

Memcache::set() will serialize non-scalar values. SplQueue does not appear to implement the SPL Serializable interface, and so cannot be relied upon to serialize/unserialize correctly. You could extend SplQueue, implement Serializable, and then construct some appropriate serialization/unserialization strategy for this purpose.

SplObjectStorage does implement Serializable, and so I would expect it to come in and out of Memcache properly.

For other SPL structures, you should check for implementation of Serializable.

Hope this helps.