Exception "Your hydrator directory must be writable." for writable directory

[maximzasorin]

Bug Report

Q	A
BC Break	no
Version	2.2.2

Summary

Exception "Your hydrator directory must be writable." occurs for a directory that definitely is writable. The exception occurs from time to time when a directory needs to be created and looks like a race condition.

The code that throws the exception is similar to this:
https://github.com/kalessil/phpinspectionsea/blob/master/docs/probable-bugs.md#mkdir-race-condition

Current behavior

I got the following exception for a directory that definitely was writable:

Your hydrator directory must be writable.
#0 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php(437): Doctrine\ODM\MongoDB\Hydrator\HydratorException::hydratorDirectoryNotWritable()
#1 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php(143): Doctrine\ODM\MongoDB\Hydrator\HydratorFactory->generateHydratorClass()
#2 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php(496): Doctrine\ODM\MongoDB\Hydrator\HydratorFactory->getHydratorFor()
#3 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/UnitOfWork.php(2690): Doctrine\ODM\MongoDB\Hydrator\HydratorFactory->hydrate()
#4 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php(635): Doctrine\ODM\MongoDB\UnitOfWork->getOrCreateDocument()
#5 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/Persisters/DocumentPersister.php(504): Doctrine\ODM\MongoDB\Persisters\DocumentPersister->createDocument()
#6 /var/www/releases/20230328170455/backend/vendor/doctrine/mongodb-odm/lib/Doctrine/ODM/MongoDB/Repository/DocumentRepository.php(172): Doctrine\ODM\MongoDB\Persisters\DocumentPersister->load()
...

How to reproduce

1. I have a web app where I use doctrine/mongodb-odm
2. I have a writable directory /some/path/temp
3. The configuration of the DocumentManager looks like this:

   $config = new Configuration;
   $config->setProxyDir('/some/path/temp/doctrine/proxy');
   $config->setHydratorDir('/some/path/temp/doctrine/hydrator');
   // ...
   DocumentManager::create(null, $config)

4. I originally got an exception on the production server when I was doing the deployment of the new version. At the moment I switched the app to the new directory /some/path/temp, I got an exception Your hydrator directory must be writable.
5. Later I was able to reproduce this in my stage environment. I first remove /some/path/temp/doctrine directory and then run: ab -c 50 -n 50 https://.... After several tries I get an exception "Your hydrator directory must be writable." in the app logs.

Expected behavior

The directory is created without any exceptions.

[malarzm]

The easiest solution is to avoid this race condition altogether and have the folders created before ODM tries to do so itself. Is that an option? There also was a schoold of pre-generating all hydrators/proxies before during deployment :)

[maximzasorin]

Yes, that's an option for me, thanks for the tip!

If I generate hydrators and proxies when I build the app before the deployment, can I leave the directories for them read-only in that case? The application code and all dependencies are not changed after the build. Build and deploy are performed on different machines.

[malarzm]

Yes, the code generation branch is executed only if the file does not exist:

mongodb-odm/lib/Doctrine/ODM/MongoDB/Hydrator/HydratorFactory.php

Lines 147 to 152 in bc49b1e

	case Configuration::AUTOGENERATE_FILE_NOT_EXISTS:
	if (! file_exists($fileName)) {
	$this->generateHydratorClass($class, $hydratorClassName, $fileName);
	}
	require $fileName;

You may also consider using Configuration::AUTOGENERATE_NEVER mode which will just fail if the file was not generated earlier.