Janitor guide

The Janitor module allows an app to program tasks to be executed periodically.

In many cases you'll need some sort of mechanism to automatically execute tasks with certain periodicity, at certain times of the day, every few days or every few minutes. The Janitor module is designed to do exactly that.

Some examples of the kind of tasks you might want to automate with Janitor are:

  • Maintenance tasks, like optimizing a database periodically.

  • Batch processes, like gathering all the invoices at the end of the day to generate daily reports.

  • Database purges, like removing old data from a database to avoid cluttering it.

  • Cache flushes, like periodically clearing certain cached data.

  • Buffer commits, like committing data stored in a shared memory buffer to a database for persistence.

Setting up the Janitor database table

Janitor uses the cherrycake_janitor_log database table to store information about the executed tasks.

You can create the Janitor table in your database by importing the janitor.sql file you'll find in the Cherrycake skeleton repository, under the install/database directory.

Janitor tasks

To set up a task to be executed by the Janitor module, you first create a new class that extends the JanitorTask core class.

Imagine we wanted to create a task to update the IMDB rating of the movies in the database every day. To do so, we would create the file classes/JanitorTaskMoviesUpdateImdbRating.class.php like this:

<?php
namespace CherrycakeApp;
class JanitorTaskMoviesUpdateImdbRating extends \Cherrycake\JanitorTask {
protected $name = "Movies update IMDB rating";
protected $description = "Updates the IMDB rating of all the movies in the database";
protected $config = [
"executionPeriodicity" => \Cherrycake\JANITORTASK_EXECUTION_PERIODICITY_HOURS,
"periodicityHours" => ["00:00"]
];
function run($baseTimestamp) {
global $e;
$e->loadCoreModule("Database");
$movies = new Movies(["fillMethod" => "fromParameters"]);
foreach ($movies as $movie)
$movie->updateImdbRating();
return [
\Cherrycake\JANITORTASK_EXECUTION_RETURN_OK,
$movies->count()." movies updated"
];
}
}

In the config property, we set the executionPeriodicity key to JANITORTASK_EXECUTION_PERIODICITY_HOURS, and the periodicityHours to ["00:00"]. This will cause this task to run once at each one of the times specified in the periodicityHours array. In this case, at midnight precisely.

With JANITORTASK_EXECUTION_PERIODICITY_HOURS, you can specify more times for tasks to be executed more than once a day. For example, if you set periodicityHours to ["00:00", "12:00"], the task will be executed every day at midnight and at noon.

There are also other execution periodicities you can use:

  • JANITORTASK_EXECUTION_PERIODICITY_EACH_SECONDS The task will be executed every specified seconds. Seconds are specified in periodicityEachSeconds config key.

  • JANITORTASK_EXECUTION_PERIODICITY_MINUTES The task will be executed on the given minutes of each hour. Desired minutes are specified as an array in the periodicityMinutes config key. For example: [0, 15, 30, 45]

  • JANITORTASK_EXECUTION_PERIODICITY_HOURS The task will be executed on the given hours of each day. Desired hours/minute are specified as an array in the periodicityHours config key in the syntax ["hour:minute", ...] For example: ["00:00", "10:45", "20:15"]

  • JANITORTASK_EXECUTION_PERIODICITY_DAYSOFMONTH The task will be executed on the given days of each month. Desired days/hour/minute are specified as an array in the periodicityDaysOfMonth config key in the syntax ["[email protected]:minute", ...] For example: ["[email protected]:00", "[email protected]:30", "[email protected]:00"]

  • JANITORTASK_EXECUTION_PERIODICITY_ALWAYS The task will be executed every time Janitor run is called.

  • JANITORTASK_EXECUTION_PERIODICITY_ONLY_MANUAL The task can only be executed when calling the Janitor run process with an specific task parameter.

In our task class, the run method is the one that will be executed when the task is due, so it's where you should put your task code. Like in our example, if you need to work with core or app modules there, use Engine::loadCoreModule or Engine::loadAppModule.

Just like you see on the example above, the run method must return an array containing at least one element, being one of the available JANITORTASK_EXECUTION_RETURN_? constants. You can add a second element containing a description of the task execution result.

Adding Janitor tasks to be executed

The last step to having your Janitor tasks automatically executed, is creating the config/Janitor.config.php file and adding them to the appJanitorTasks configuration key.

In our example, the config/Janitor.config.php would look like this:

<?php
namespace Cherrycake;
$JanitorConfig = [
"appJanitorTasks" => [
"JanitorTaskMoviesUpdateImdbRating"
]
];

Cherrycake core Janitor tasks

Cherrycake itself sets up by default the following core Janitor tasks:

  • JanitorTaskJanitorPurge Performs maintenance tasks related to the Janitor module itself, like purging old log items from the database.

  • JanitorTaskSystemLogPurge Performs maintenance tasks related to the SystemLog module, like purging old log items from the database.

  • JanitorTaskSystemLogCommit Commits the SystemLog events stored in the cache shared memory to the database for persistence and for optimal performance.

  • JanitorTaskSessionPurge Performs maintenance tasks related to the Session module, like purging old sessions.

  • JanitorTaskStatsCommit Commits the Stats events stored in the cache shared memory to the database for persistence and for optimal performance.

  • JanitorTaskLogCommit Commits the Log events stored in the cache shared memory to the database for persistence and for optimal performance.

Setting up the Janitor cron job

To let Janitor do its job, the CLI action named janitorRun must be executed every minute automatically by the operating system in the server. This is usually done by setting up a cron job in Linux that does it by using the Cherrycake Command line interface.

In Linux, you would set up the Janitor cron job by editing your crontab with the command:

crontab -e

And adding a line like this:

* * * * * /var/www/app/cherrycake janitorRun

If you've not used the Cherrycake Skeleton to build your project, take a look at the Command line interface section to learn how to call CLI actions from the Linux command line.

When using the Cherrycake Docker project to run your Cherrycake app, this cron job is already set up and running.

Checking the status of the Janitor

The Janitor logs all its activity on the cherrycake_janitor_log, so you can check there to see what's happening in real time.

You can also execute the janitorStatus CLI command, which will show you the current status of all the tasks in your app, plus information about the last time they were executed. It looks like this:

Task: Janitor purge
Description: Purges old Janitor log items
Result: Ok
Periodicity: Every 86400 seconds
Last execution: 26/5/2020 15:10:59 (Etc/UTC) took 0 ms.
. Log entries older than 31536000 seconds purged: 0
Task: Log commit
Description: Stores cache-queded events into database and purges the queue cache
Result: Ok
Periodicity: Every 60 seconds
Last execution: 26/5/2020 15:12:01 (Etc/UTC) took 0 ms.
.
Task: Session purge
Description: Purges discarded sessions from the Session module
Result: Ok
Periodicity: Every 86400 seconds
Last execution: 26/5/2020 15:10:59 (Etc/UTC) took 2 ms.
. Sessions older than 86400 seconds without data purged: 0
. Sessions older than 31536000 seconds with data purged: 0
Task: Stats commit
Description: Stores cache-queded stats events into database and purges the queue cache
Result: Ok
Periodicity: Every 60 seconds
Last execution: 26/5/2020 15:12:01 (Etc/UTC) took 1 ms.
. numberOfFlushedItems: 0
Task: System log commit
Description: Stores cache-queded system log events into database and purges the queue cache
Result: Ok
Periodicity: Every 120 seconds
Last execution: 26/5/2020 15:10:59 (Etc/UTC) took 1 ms.
. numberOfFlushedItems: 0
Task: System log purge
Description: Purges old System log items
Result: Ok
Periodicity: Every 240 seconds
Last execution: 26/5/2020 15:10:59 (Etc/UTC) took 1 ms.
. Log entries older than seconds purged: 0
Task: Movies update IMDB rating
Description: Updates the IMDB rating of all the movies in the database
Result: Ok
Periodicity: Daily at hours 00:00
Last execution: 26/5/2020 15:10:59 (Etc/UTC) took 13 ms.
. 30 movies updated