Queue for Kirby

This plugin adds a basic queue to the Kirby CMS, using Cron and Kirby's flat file system.

Installation

Copy the files of this repo to your site/plugins folder. You can also run kirby plugin:install sebsel/queue-for-kirby if you have the CLI tools installed.

You then need to add site/plugins/queue-for-kirby/worker.php to your Cron Jobs or similar software, for once per minute, depending on how fast you want your jobs done. You can even move this file if you want, but make sure to change the require path to point at kirby/bootstrap.php, so it can load Kirby.

The plugin will try to create the folder site/queue and some files and folders within it.

Configuration

The plugin is designed to be used in other plugins, see below for examples.

Please note: your domain specific configuration-files (config.example.com.php) might not have been loaded when you run the worker.

Widget

This plugin will add a widget to the panel dashboard if there are failed jobs, or if there are more than 5 jobs in the queue (indicating that there's something wrong).

How to define jobs

You need to define the following things within the base-file of your plugin, not in any lazy loaded classes (with Kirby's load() or composer's autoloading). Just put it in site/plugins/your_plugin/your_plugin.php.

// Make sure that the Queue plugin is loaded.
kirby()->plugin('queue-for-kirby');
if(!class_exists('queue')) throw new Exception('This plugin requires the Queue for Kirby plugin');

// Define a job by giving it a name and an action
queue::define('send_webmention', function($job) {

    // Get your data
    $target = $job->get('target');
    $source = $job->get('source');

    // Do something with your data, for example: send a webmention!
    if(!send_webmention($target, $source)) {
        // Throw an error to fail a job
        throw new Error('Sending webmention failed');
        // or just return false, but setting a message for the user is better.
    }

    // No need to return or display anything else!
});

Then, anywhere else in your plugin code, you can call queue::add() to schedule a new job. This will also work in the lazy loaded classes, if you added the previous step to your plugin base-file.

// Schedule a job by giving a job-name and the data you need
queue::add('send_webmention', [
    'target' => $target,
    'source' => $source
]);

The data you pass in is up to you: you can define your own jobs. The only caveat is that the data needs to be stored in YAML. To access a Page object, you can use:

queue::define('some_page_action', function($job) {
    $page = page($job->get('page'));
});

// and

queue::add('some_page_action', [
    'page' => $page->id()
]);

Do not forget to add site/plugins/queue-for-kirby/worker.php to a Cron Job, or your jobs will sit in the queue forever!

Failed jobs

Failed jobs are currently added to site/queue/.failed, with some information about the error attached. They will not be retried automatically. To trigger them again, just move them one folder down to site/queue and make sure the worker runs.

To fail a job, either throw an exception or return false.

Available methods

The following static methods are available on this class:

queue::define($name, $action)

Define a new action that should be executed once the job is handled by the worker.

queue::define('job_name', function($job) {
    // Do something
});

queue::add($name, $data = null)

Add a new job to the queue. The data you pass in can be anything, as long as it can be stored in YAML. The data can be empty.

queue::add('job_name', [
    'param' => 'some data'
]);

queue::add('another_job');

queue::jobs()

Returns a Collection of Job objects, for all jobs in the queue.

Doing something with these jobs does not change the queue. Only queue::work() removes jobs from the queue.

queue::jobs();
// Returns, for example:
object(Collection) {
    object(Job) {
        'id' => '5975f78ed3db6',
        'added' => '2001-01-01T01:01:01+00:00',
        'name' => 'job_name',
        'data' => [
            'param' => 'some data'
        ]
    },
    object(Job) {
        'id' => '5975f78ed303f',
        'added' => '2001-01-01T01:01:02+00:00',
        'name' => 'another_job',
        'data' => null
    }
}

// and

queue::jobs()->first();
// returns the first Job

queue::failedJobs()

Returns a Collection of Job objects, representing the failed jobs.

queue::failedJobs();
// Returns, for example:
object(Collection) {
    object(Job) {
        'id' => '5975f78ed3db6',
        'added' => '2001-01-01T01:01:01+00:00',
        'name' => 'job_name',
        'data' => [
            'param' => 'some data'
        ],
        'error' => 'Job returned false',
        'tried' => '2001-01-01T01:01:03+00:00'
    }
}

// and

queue::failedJobs()->last();
// returns the last failed Job

queue::retry($failedJob)

Moves a failed job back in the queue. Use to trigger in a panel widget or after some other user input.

Note that this does not immediately act on the failed job. It is just added to the queue – probably at the front due to it's old ID – and gets handled as soon as your Cron Job executes worker.php.

$failedJob = queue::failedJobs()->first();

queue::retry($failedJob);

// or

queue::retry('5975f78ed3db6');

queue::remove($failedJob)

Removes a failed job entirely. Note that this only works for failed jobs.

$failedJob = queue::failedJobs()->last();

queue::remove($failedJob);

// or

queue::remove('5975f78ed3db6');

queue::work()

Executes the first job in the queue. Don't call this one outside of worker.php, because that would defeat the purpose of the queue.

queue::hasJobs()

Returns true or false, depending on wether there are jobs in the queue.

queue::flush()

Removes all jobs from the queue, including failed jobs.

queue::path()

Returns the full path of site/queue.

queue::failedPath()

Returns the full path of site/queue/.failed.

Job methods

On a Job object, you can find the following methods:

$job->get($key)

Tries to get the value under $key from the $data array. (You can also pass a non-array to $data, in which case $job->get('some_key') will return null, and you have to use $job->data() to get it.)

queue::define('job_name', function($job) {
    $job->get('param');
    // contains 'some data' in the job added below
});

queue::add('job_name', [
    'param' => 'some data'
]);

$job->data()

Returns the $data that was passed in when the job was created.

$job->id()

Returns the ID of the job, which is a unique identifier for the job. This is also the filename, minus '.yml'.

$job->name()

Returns the name of the job, which is the name of the action that is performed when working on the job.

$job->added()

Returns the date the job was added to the queue, formatted as date('c') (2001-01-01T01:01:01+00:00).

$job->error()

Returns the error for a failed job, or null on a normal one.

$job->tried()

Returns the date the job was last tried to execute, formatted as date('c') (2001-01-01T01:01:01+00:00). This will be null for non-failed jobs.