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.. Copyright (C) 2014-2023 Champs Libres Cooperative SCRLFS
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU
Free Documentation License".
.. _cronjob:
Cron jobs
*********
Some tasks must be executed regularly: refresh some materialized views, remove old data, ...
For this purpose, one can programmatically implements a "cron job", which will be scheduled by a specific command.
The command :code:`chill:cron-job:execute`
==========================================
The command :code:`chill:cron-job:execute` will schedule a task, one by one. In a classical implementation, it should
be executed every 15 minutes (more or less), to ensure that every task can be executed.
.. warning::
This command should not be executed in parallel. The installer should ensure that two job are executed concurrently.
How to implements a cron job ?
==============================
Implements a :code:`Chill\MainBundle\Cron\CronJobInterface`. Here is an example:
.. code-block:: php
namespace Chill\MainBundle\Service\Something;
use Chill\MainBundle\Cron\CronJobInterface;
use Chill\MainBundle\Entity\CronJobExecution;
use DateInterval;
use DateTimeImmutable;
use Symfony\Component\Clock\ClockInterface;
class MyCronJob implements CronJobInterface
{
function __construct(private ClockInterface $clock) {}
public function canRun(?CronJobExecution $cronJobExecution): bool
{
// the parameter $cronJobExecution contains data about the last execution of the cronjob
// if it is null, it should be executed immediatly
if (null === $cronJobExecution) {
return true;
}
if ($cronJobExecution->getKey() !== $this->getKey()) {
throw new UnexpectedValueException();
}
// this cron job should be executed if the last execution is greater than one day, but only during the night
$now = $clock->now();
return $cronJobExecution->getLastStart() < $now->sub(new DateInterval('P1D'))
&& in_array($now->format('H'), self::ACCEPTED_HOURS, true)
// introduce a random component to ensure a roll of task execution when multiple instances are hosted on same machines
&& mt_rand(0, 5) === 0;
}
public function getKey(): string
{
return 'arbitrary-and-unique-key';
}
public function run(array $lastExecutionData): void
{
// here, we execute the command
// we return execution data, which will be served for next execution
// this data should be easily serializable in a json column: it should contains
// only int, string, etc. Avoid storing object
return ['last-execution-id' => 0];
}
}
How are cron job scheduled ?
============================
If the command :code:`chill:cron-job:execute` is run with one or more :code:`job` argument, those jobs are run, **without checking that the job can run** (the method :code:`canRun` is not executed).
If any :code:`job` argument is given, the :code:`CronManager` schedule job with those steps:
* the tasks are ordered, with:
* a priority is given for tasks that weren't never executed;
* then, the tasks are ordered, the last executed are the first in the list
* then, for each tasks, and in the given order, the first task where :code:`canRun` return :code:`TRUE` will be executed.
The command :code:`chill:cron-job:execute` execute **only one** task.