Single Process Command

gistfile1.php

// src/Trq/FooBundle/Helper/SingleProcess.php

<?php

namespace Trq\FooBundle\Helper;

class SingleProcess
{
    protected $callback;
    protected $fp;

    public function __construct($name, callable $callback)
    {
        $this->fp = fopen("/tmp/{$name}.lock", "w");
        $this->callback = $callback;
    }

    public function __destruct()
    {
        fclose($this->fp);
    }

    protected function lockObtained()
    {
        return flock($this->fp, LOCK_EX | LOCK_NB);
    }

    protected function dropLock()
    {
        flock($this->fp, LOCK_UN);
    }

    public function process()
    {
        if ($this->lockObtained()) {
            $result = call_user_func($this->callback);
            $this->dropLock();
            return $result;
        } else {
            throw new \RuntimeException('Unable to obtain the lock');
        }
    }
}

// src/Trq/FooBundle/Command/TestCommand.php
<?php

namespace Trq\FooBundle\Command;

use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

use Trq\FooBundle\Helper\SingleProcess;

class TestCommand extends ContainerAwareCommand
{
    /**
     * @see Command
     */
    protected function configure()
    {
        $this->setName('trq:test');
    }

    /**
     * @see Command
     */
    protected function execute(InputInterface $input, OutputInterface $output)
    {
        try {
            (new SingleProcess('trq.test', function() use ($output) {
                foreach (range(0, 10) as $i) {
                    $output->writeln('<fg=green>Hello World!</fg=green>');
                    sleep(1);
                }
            }))->process();
        } catch (\RuntimeException $e) {
            $output->writeln('<fg=red>' . $e->getMessage() . '</fg=red>');
        }
    }
}