John Davidson

Message:

On Symfony 4.4, I am trying to establish a lock in a command and keep it alive until explicitly released. Reading the docs I understand that this should be obtained with the $autoRelease param of Symfony\Component\Lock\LockFactory::createLock(), but it seems that even if I set $autoRelease = false the lock is automatically released when the script ends.

LockCommand

<?php

namespace App\Command;



use Symfony\Component\Console\Command\Command;

use Symfony\Component\Console\Input\InputInterface;

use Symfony\Component\Console\Input\InputOption;

use Symfony\Component\Console\Output\OutputInterface;

use Symfony\Component\Lock\LockFactory;





class LockCommand extends Command

{

    const LOCK_NAME = "my_lock";



    protected static $defaultName = 'app:lock';



    private $lockFactory;



    public function __construct(LockFactory $lockFactory)

    {

        $this->lockFactory = $lockFactory;

        parent::__construct();

    }    



    protected function configure()

    {

        $this

            ->setDescription("Enables/disables the lock.")

            ->addOption(

                'release',

                'r',

                InputOption::VALUE_NONE,

                'Releases the lock'

            )

        ;

    }    



    protected function execute(InputInterface $input, OutputInterface $output)

    {

        $lock = $this->lockFactory->createLock(self::LOCK_NAME, 300.0, false);



        $release = $input->getOption('release');

        

        if ($release) {

            $lock->release();

        } else {

            $lock->acquire();

        }



        //sleep(300);



        return 0;

    }    

}

LockVerifyCommand

<?php

namespace App\Command;



use Symfony\Component\Console\Command\Command;

use Symfony\Component\Console\Input\InputInterface;

use Symfony\Component\Console\Output\OutputInterface;

use Symfony\Component\Lock\LockFactory;



class LockVerifyCommand extends Command

{

    protected static $defaultName = 'app:lock-verify';



    private $lockFactory;



    public function __construct(LockFactory $lockFactory)

    {

        $this->lockFactory = $lockFactory;

        parent::__construct();

    }    



    protected function execute(InputInterface $input, OutputInterface $output)

    {

        $lock = $this->lockFactory->createLock(LockCommand::LOCK_NAME, 300.0, false);

        $status = $lock->acquire() ? "no" : "yes";

        $output->writeln("Locked? $status");



        return 0;

    }

}

I would expect to be able to

1. enable the lock php bin/console app:lock


2. php bin/console app:lock-verify should say Locked? yes


3. until I release the lock php bin/console app:lock --release

this happens only while the app:lock command is running.

---

My Answer:
To set a lock in a command and keep it alive until explicitly released, you can use the Symfony Lock component in your command. Here's an example of how you can achieve this:

php
// src/Command/LockCommand.php

namespace App\Command;

use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
use Symfony\Component\Lock\LockFactory;
use Symfony\Component\Lock\Store\FlockStore;

class LockCommand extends Command
{
protected static $defaultName = 'app:lock-command';

protected function configure()
{
$this->setDescription('Command with lock');
}

protected function execute(InputInterface $input, OutputInterface $output)
{
$store = new FlockStore(sys_get_temp_dir());
$lockFactory = new LockFactory($store);
$lock = $lockFactory->createLock('my_lock', 0, false);

if ($lock->acquire()) {
$output->writeln('Lock acquired successfully');
// Do your work here

// To release the lock explicitly
// $lock->release();
} else {
$output->writeln('Could not acquire lock');
}

return Command::SUCCESS;
}
}


In this example, we create a lock using the `LockFactory` with the `FlockStore` as the store. We set the `$autoRelease` parameter to `false` when creating the lock. The `acquire()` method is used to acquire the lock, and if successful, we can perform our work within the locked section. To release the lock explicitly, you can call the `release()` method on the lock.

Remember to register your command in the `services.yaml` file or wherever you define your services in Symfony.

yaml
# config/services.yaml

services:
App\Command\LockCommand:
tags: ['console.command']


Now you can run your command using `php bin/console app:lock-command` and the lock will be kept alive until explicitly released.