Doc: [cronjob manager] Doc for implementing cronjob

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] ';