Doc: [cronjob manager] Doc for implementing cronjob

docs/source/development/cronjob.rst

@@ -0,0 +1,93 @@
+
+.. 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;
+
+    class MyCronJob implements CronJobInterface
+    {
+        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 = new DateTimeImmutable('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(): void
+        {
+            // here, we execute the command
+        }
+    }
+
+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.
+
+
+

docs/source/development/index.rst

@@ -34,6 +34,7 @@ As Chill rely on the `symfony <http://symfony.com>`_ framework, reading the fram
     Useful snippets <useful-snippets.rst>
     manual/index.rst
     Assets <assets.rst>
+    Cron Jobs <cronjob.rst>
 
 Layout and UI
 **************

docs/source/installation/prod.rst

@@ -6,6 +6,8 @@ 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".
 
+.. _prod:
+
 Installation for production
 ###########################
 
@@ -36,6 +38,19 @@ This should be adapted to your needs:
 
 * Think about how you will backup your database. Some adminsys find easier to store database outside of docker, which might be easier to administrate or replicate.
 
+Cron jobs
+=========
+
+The command :code:`chill:cron-job:execute` should be executed every 15 minutes (more or less).
+
+This command should never be executed concurrently. It should be not have more than one process for a single instance.
+
+Post-install tasks
+==================
+
+- import addresses. See :ref:`addresses`.
+
+
 Tweak symfony messenger
 =======================
 

src/Bundle/ChillMainBundle/Cron/CronManager.php

@@ -19,6 +19,25 @@ use Exception;
 use Psr\Log\LoggerInterface;
 use function array_key_exists;
 
+/**
+ * Manage cronjob and execute them.
+ *
+ * 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 error inside job execution are catched (with the exception of _out of memory error_).
+ *
+ * The manager will mark the task as executed even if an error is catched. This will lead as failed job
+ * will not have priority any more on other tasks.
+ *
+ * If a tasks is "forced", there is no test about eligibility of the task (the `canRun` method is not called),
+ * and the last task execution is not recorded.
+ */
 class CronManager implements CronManagerInterface
 {
     private const LOG_PREFIX = '[cron manager] ';

src/Bundle/ChillMainBundle/Cron/CronManagerInterface.php

@@ -13,5 +13,11 @@ namespace Chill\MainBundle\Cron;
 
 interface CronManagerInterface
 {
+    /**
+     * Execute one job, with a given priority, or the given job (identified by his key)
+     *
+     * @param string|null $forceJob
+     * @return void
+     */
     public function run(?string $forceJob = null): void;
 }