Zend Server and APC functionality

[kategray]

Zend Server tries to implement compatibility with apc by registering compatibility functions with the same name as the APC functions.

http://files.zend.com/help/Zend-Server-6/content/zend_data_cache_-_configuration_directives.htm

Specifically, the option is "zend_datacache.apc_compatibility". It looks like it gets aliased to zend_shm_cache_store, which mostly works. Unfortunately, it doesn't support the array form of apc_store(), so every call results in errors:

"apc_store() expects parameter 1 to be string, array given"

It looks like this is a problem that other projects have dealt with, and it looks like it's one that's been going on for 8 years or so, so I'm not expecting Zend to fix it anytime soon.

My inclination would be to add a check to see if the parameter to apcu_add() or apcu_store() is an array, and if so to call the apc function individually for each item in the array. It would maintain compatibility with APC, and fix the issues with Zend Server. It's a little bit of a hack, though, and I figured I'd ask before submitting a PR.

Alternatively, I could add support for Zend Data Cache to the Symfony Cache Component.

[stof]

I don't think we ever call apc_store directly in Symfony anymore.
Can you give the stack trace of the error to see where it happens ?

[kategray]

32	apc_store([...])	<builtin>	
31	apcu_store([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/polyfill/src/Apcu/bootstrap.php:27	
30	Symfony\Component\Cache\Adapter\ApcuAdapter::doSave([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/Cache/Adapter/ApcuAdapter.php:95	
29	Symfony\Component\Cache\Adapter\AbstractAdapter::commit()	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php:335	
28	Symfony\Component\Cache\Adapter\AbstractAdapter::save([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/Cache/Adapter/AbstractAdapter.php:304	
27	Symfony\Component\Cache\Adapter\ChainAdapter::save([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/Cache/Adapter/ChainAdapter.php:199	
26	Symfony\Component\Cache\Adapter\PhpArrayAdapter::save([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/Cache/Adapter/PhpArrayAdapter.php:298	
25	Symfony\Component\Cache\DoctrineProvider::doSave([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/Cache/DoctrineProvider.php:58	
24	Doctrine\Common\Cache\CacheProvider::save([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/cache/lib/Doctrine/Common/Cache/CacheProvider.php:132	
23	Doctrine\Common\Annotations\CachedReader::saveToCache([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/annotations/lib/Doctrine/Common/Annotations/CachedReader.php:207	
22	Doctrine\Common\Annotations\CachedReader::getClassAnnotations([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/annotations/lib/Doctrine/Common/Annotations/CachedReader.php:80	
21	Doctrine\ORM\Mapping\Driver\AnnotationDriver::loadMetadataForClass([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/orm/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php:63	
20	Doctrine\Common\Persistence\Mapping\Driver\MappingDriverChain::loadMetadataForClass([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/common/lib/Doctrine/Common/Persistence/Mapping/Driver/MappingDriverChain.php:102	
19	Doctrine\ORM\Mapping\ClassMetadataFactory::doLoadMetadata([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/orm/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php:151	
18	Doctrine\Common\Persistence\Mapping\AbstractClassMetadataFactory::loadMetadata([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/common/lib/Doctrine/Common/Persistence/Mapping/AbstractClassMetadataFactory.php:332	
17	Doctrine\ORM\Mapping\ClassMetadataFactory::loadMetadata([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/orm/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php:78	
16	Doctrine\Common\Persistence\Mapping\AbstractClassMetadataFactory::getMetadataFor([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/common/lib/Doctrine/Common/Persistence/Mapping/AbstractClassMetadataFactory.php:216	
15	Doctrine\ORM\EntityManager::getClassMetadata([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php:281	
14	Doctrine\ORM\Repository\DefaultRepositoryFactory::getRepository([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/orm/lib/Doctrine/ORM/Repository/DefaultRepositoryFactory.php:44	
13	Doctrine\ORM\EntityManager::getRepository([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/doctrine/orm/lib/Doctrine/ORM/EntityManager.php:698	
12	EntityManager5947a4308dcd8_546a8d27f194334ee012bfe64f629947b07e4919\__CG__\Doctrine\ORM\EntityManager::getRepository([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/var/cache/prod/jms_diextra/doctrine/EntityManager_5947a4308dcd8.php:165	
11	appProdProjectContainer::getMadeline_SiteConfigurationRepositoryService()	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/var/cache/prod/appProdProjectContainer.php:2345	
10	Symfony\Component\DependencyInjection\Container::get([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/Container.php:311	
9	appProdProjectContainer::getMadeline_SiteConfigurationListenerService()	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/var/cache/prod/appProdProjectContainer.php:2332	
8	Symfony\Component\DependencyInjection\Container::get([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/Container.php:311	
7	Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher::lazyLoad([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/EventDispatcher/ContainerAwareEventDispatcher.php:181	
6	Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher::getListeners([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/EventDispatcher/ContainerAwareEventDispatcher.php:127	
5	Symfony\Component\EventDispatcher\EventDispatcher::dispatch([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/EventDispatcher/EventDispatcher.php:42	
4	Symfony\Component\HttpKernel\HttpKernel::handleRaw([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php:129	
3	Symfony\Component\HttpKernel\HttpKernel::handle([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/HttpKernel.php:68	
2	Symfony\Component\HttpKernel\Kernel::handle([...])	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Kernel.php:168	
1	{main}	/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72/web/app.php:13

[kategray]

I was able to resolve the issue by patching as described:

https://github.com/kategray/polyfill/commit/e4d9188d6e68835625328c4785529b72b039ba11

[kategray]

symfony/polyfill                     v1.4.0             Symfony polyfills backporting features to lower PHP versions
symfony/swiftmailer-bundle           v2.6.2             Symfony SwiftmailerBundle
symfony/symfony                      v3.2.9             The Symfony PHP framework

[stof]

hmm, we could indeed handle this case in your APCu polyfill. It would fix things for people using the APCu polyfill.

@nicolas-grekas should be handle this internally in the polyfill, or should we just skip the polyfill if we detect that the apc functions are not the real ones by the Zend Server buggy shim ?

[kategray]

It looks like createSystemCache() in Symfony/Component/Cache/Adapter/AbstractAdapter.php is checking if APCU is supported. The actual check is

return function_exists('apcu_fetch') && ini_get('apc.enabled') && !('cli' === PHP_SAPI && !ini_get('apc.enable_cli'));
It returns true with the Zend Cache compatibility layer enabled (as it is by default).

[kategray]

@stof I believe you can detect if it's the genuine APC by doing a version check like so:

kate@ubuntu:/usr/local/zend/var/apps/http/madeline.local/80/ddcb30-dirty_72$ php
<?php
var_dump(phpversion('apc'));
bool(false)

[stof]

@kategray currently, it reports it as supported, yes, as our polyfill-apcu package accepts polyfilling APCu on top of the Zend Server APC polyfill.

APCuAdapter only cares about APCu, and Zend Server does not mess with it. So this is not the place to add support for the APC messed polyfill.
This is why I said we should fix it at the polyfill-apcu level: either handling the quirk on apc_store on Zend Server, or disabling the APCu polyfill entirely by considering that APC is not available.
@nicolas-grekas what do you think about that decision ? Handle broken APC polyfill or forbid it ?

[kategray]

@stof I agree - that's why I made the changes on my fork in the polyfill-apcu level.

If you and @nicolas-grekas would like me to do a pull request for the patch in my fork (the one that converts arrays to individual calls, maintaining compatibility with apc's error handling for the array syntax), I'd be glad to do so.

If not, I'll go ahead and delete my fork.

[nicolas-grekas]

We should handle that in the APCu polyfill yes.
We should just find a proper check to do that foreach only when ZS is used. Original APC should be used straight with arrays.

[kategray]

So, have separate functions for zend's APC emulation, and select which one in the bootstrap?

[nicolas-grekas]

Yep

[kategray]

Would you like me to do that?

[nicolas-grekas]

Please :) I'm almost AFK for two weeks on my side.

[kategray]

I ended up adding a second bootstrap.php, just for zend. It was cleaner than having two sets of functions in the same bootstrap file.

I added a couple of unit tests - they pass on PHP 5.4 with APC. Unfortunately, Zend Cache flat-out refuses to work in the CLI, so I just disable the compatibility when running from the CLI.