Laravel Singleton

App\Console\AbstractSingletonCommand.php

<?php

namespace App\Console;

use Illuminate\Console\Command;

/**
 * Class PidLockingCommand
 *
 * Implements a command with pidlocking control to avoid conflicting processing
 * Extend this class and call parent::handle() on top of your handle().
 *
 * @package App\Console\Commands
 */
abstract class AbstractSingletonCommand extends Command
{
    /**
     * @var Lock file with PID value, used to avoid running the importer while still extracting data
     */
    protected $pidFile;

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

    public function getPid()
    {
        if (file_exists($this->pidFile)) {
            $pid = file_get_contents($this->pidFile);
            return $this->checkIfProcessIsReallyRunning($pid);
        } else {
            return null;
        }
    }

    public function checkIfProcessIsReallyRunning($pid)
    {
        $pids = '';
        $fp = popen("ps ax -o pid --noheaders", "r");
        while (!feof($fp)) {
            $pids .= fread($fp, 1024);
        }
        fclose($fp);

        $pids = explode("\n", $pids);
        if (!in_array($pid, $pids)) {
            unlink($this->pidFile);
            return null;
        }
        return $pid;
    }

    protected function setPid()
    {
        file_put_contents($this->pidFile, getmypid());
    }

    protected function removePidLock()
    {
        if (file_exists($this->pidFile) && $this->checkMyPid()) {
            unlink($this->pidFile);
        }
    }

    protected function checkMyPid()
    {
        return $this->getPid() == getmypid();
    }

    protected function generateFileName()
    {
        return base_path() . DIRECTORY_SEPARATOR .
            "storage" .
            DIRECTORY_SEPARATOR .
            snake_case($this->getSingleClassName());
    }

    protected function setPidFile()
    {
        $this->pidFile = $this->generateFileName() . '.pid';
    }

    public function getSingleClassName($class = null)
    {
        $class = is_string($class) ? $class : get_class($this);
        $class = explode('\\', $class);
        return $class[count($class) - 1];
    }

    public function __construct()
    {
        parent::__construct();
        $this->setPidFile();
    }

    public function handle()
    {
        // if no process is running
        if (!$this->getPid()) {
            $this->setPid();
        }

        if ($this->getPid() && !$this->checkMyPid()) {
            trigger_error('Previous ' . $this->getSingleClassName() . ' process still running!!!', E_USER_ERROR);
        }
    }
}