Inhibit concurrent execution of Update::updateToCurrentVersion() #6457
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It turns out that TravisCI supports PHP Semaphores 😉 |
mlocati
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Feb 21, 2018
| @@ -198,7 +199,9 @@ public function handleAutomaticUpdates() | |||
| $installed = $config->get('concrete.version_db_installed'); | |||
| $core = $config->get('concrete.version_db'); | |||
| if ($installed < $core) { | |||
| Update::updateToCurrentVersion(); | |||
| $this->make(MutexInterface::class)->execute(Update::MUTEX_KEY, function() { | |||
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What should we do if the Update::updateToCurrentVersion() is already in progress?
With this code we have an uncaught Concrete\Core\System\Mutex\MutexBusyException exception.
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Can we make it so that the maintenance mode view is rendered if this is the case?
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Sure! Here it is: #6480
This is needed because someone may set the concrete5 temporary directory to point to a folder shared across multiple concrete5 instances.
If we use a custom algorithm to determine the ID of a semaphore, there's a (remote) possibility to end up using a semaphore defined by other system apps.
The temporary directory may be shared across multiple concrete5 instances, and we need to be sure that the mutex are instance-specific.
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On high-traffic sites, we may have that
Update::updateToCurrentVersion()is executed simultaneously more that one time, leading to unexpected results.What about protecting us from that by using mutex?
I added two mutex implementations here: one based on PHP Semaphores (it requires that PHP is compiled with the
--enable-sysvsemoption), and another one based on file locks.I also included a test case to check that these mutex works. I don't think that TravisCI supports Semaphores by default, but I tested with a PHP 7.0 compiled with
--enable-sysvsemand test passes.