Prerequisites

WP_Queue requires PHP 5.3+.

The following database tables need to be created:

CREATE TABLE {$wpdb->prefix}queue_jobs (
id bigint(20) NOT NULL AUTO_INCREMENT,
job longtext NOT NULL,
attempts tinyint(3) NOT NULL DEFAULT 0,
reserved_at datetime DEFAULT NULL,
available_at datetime NOT NULL,
created_at datetime NOT NULL,
PRIMARY KEY  (id)

CREATE TABLE {$wpdb->prefix}queue_failures (
id bigint(20) NOT NULL AUTO_INCREMENT,
job longtext NOT NULL,
error text DEFAULT NULL,
failed_at datetime NOT NULL,
PRIMARY KEY  (id)

Alternatively, you can call the wp_queue_install_tables() helper function to install the tables. If using WP_Queue in a plugin you may opt to call the helper from within your register_activation_hook.

Jobs

Job classes should extend the WP_Queue\Job class and normally only contain a handle method which is called when the job is processed by the queue worker. Any data required by the job should be passed to the constructor and assigned to a public property. This data will remain available once the job is retrieved from the queue. Let's look at an example job class:

<?php

use WP_Queue\Job;

class Subscribe_User_Job extends Job {

	/**
	 * @var int
	 */
	public $user_id;

	/**
	 * Subscribe_User_Job constructor.
	 *
	 * @param int $user_id
	 */
	public function __construct( $user_id ) {
		$this->user_id = $user_id;
	}

	/**
	 * Handle job logic.
	 */
	public function handle() {
		$user = get_user_by( 'ID', $this->user_id );
		
		// Process the user...
	}

}

Dispatching Jobs

Jobs can be pushed to the queue like so:

wp_queue()->push( new Subscribe_User_Job( 12345 ) );

You can create delayed jobs by passing an optional second parameter to the push method. This job will be delayed by 60 minutes:

wp_queue()->push( new Subscribe_User_Job( 12345 ), 3600 );

Cron Worker

Jobs need to be processed by a queue worker. You can start a cron worker like so, which piggy backs onto WP cron:

wp_queue()->cron();

You can also specify the number of times a job should be attempted before being marked as a failure.

wp_queue()->cron( 3 );

License

WP Queue is open-sourced software licensed under the MIT license.