[WIP] ApcuStorage: user cache from APC

[fprochazka]

APC opcode caching might be dead, because the zend optimizer plus is now native for 5.5+,
but the APCu is still alive and thriving. And I think It's pretty good storage option for some types of cache. Therefore I propose adding new storage supporting it.

I've copied the tests from memcached and rewritten them for the new storage.

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There is a problem - Apcu clears cache depending on TTL only when new request occurs - which means It cannot be easily tested. Any idea how to test it?

Or should I implement "fallback" expiration check that will store when the key should be expired and then expire it manually if neccesary?

[Majkl578]

Nice, but 👎 for adding it to the repository, it's only rarely used.

[fprochazka]

I have no problem with creating kdyby/apcu-storage, but I thought it might be usefull here.

[dg]

ApcStorage was is Nette 4 year ago https://github.com/nette/outdated-addons/blob/master/ApcStorage/ApcStorage.php, but was removed due to some problems, but I can't remember…

[fprochazka]

@dg so should I solve the issues with testing the storage and it will be accepted, or should I create new kdyby package?

[dg]

I remember that there were really serious problems, but I am unable to google it :-(

[dg]

here: nette/nette@b0ed629#commitcomment-110757

[fprochazka]

Interesting, I will investigate and try to debug it. But from a quick look, I can tell the current APCu does not have this "feature" - we're using it for metadata storage and the string is not in logs for the last month.

[fprochazka]

In fact, I've also copied this class as is, to our codebase and deployed to production last night and also no problems.

[dg]

Probably it is related to apc.slam_defense and apc.write_lock. When slam defense is configurable, I am 👍 for merge.

[Majkl578]

So are we now going to support every backend only few people use - like Redis, MySQL, NoSQL DBs etc.?

[Majkl578]

@dg: No idea why you are mentioning those two directives. First one only enables/disables slamming (which should be on), it can't configure frequency or something. Second one does not even exist in APCu.

[foxycode]

I am 👍 for merge

[dg]

It is not possible to merge when tests are failing.

[fprochazka]

I have very little time to work on it right now, but I'm planning to finish it. As always, if anybody wants to finish it and has the time, you're welcome to take over.

[dg]

ping @fprochazka

[tomasstrejcek]

@fprochazka @Majkl578 its pretty simple, really

APC/APCu cache is based on HTTP(CLI) requests

What the doc means by the stored variable will be expunged from the cache (on the next request)
(http://us3.php.net/manual/en/function.apcu-store.php)

the cache is going to be expunged when the script is next run, so only solution is to run subprocess or something to get it working

the cache is never gonna expire in long running process - but it shouldnt matter depending on what are you using the cache on

perhaps sth like (i dont like but..):

sleep(3);
$cmd = shell_exec('php loadExpiredKey.php');
Assert::equal($cmd, '1');

loadExpiredKey.php:

$cache = new Cache(new ApcuStorage());
echo $cache->load($key) == null;

[dg]

ping @fprochazka