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dot-queue

DotKernel queue component

Note

dot-queue is abandoned and will receive no further development!

Requirements

• PHP >= 7.1
• zendframework/zend-servicemanager
• zendframework/zend-db (optional - install if using the database adapter)

Installation

Run the following command

After installing all dependencies, add the \Dot\Queue\ConfigProvider::class to your configuration aggregate, in order to register all dependencies and console commands.

Queues

The following queue implementations are provided by this package

• Dot\Queue\Queue\InMemoryQueue - non-persisten queue, based on \SplQueue, mainly for testing purposes
• Dot\Queue\Queue\PersistentQueue - uses an adapter to persist/fetch jobs to/from a storage

Queues must implement Dot\Queue\Queue\QueueInterface or extend Dot\Queue\Queue\AbstractQueue.

Queue adapters

Queue adapters are used in collaboration with the PersistentQueue. Queue adapters are specific to the storage used Provided queue adapters:

• Dot\Queue\Adapter\DatabaseAdapter - based on zend-db, enqueues/dequeues jobs using a MySql storage

Queue adapters must implement Dot\Queue\Adapter\AdapterInterface

Configuring queues

At this moment, the package offers only a database adapter to be used with the persistent queue. Therefore, the config template below shows how to configure a MySQL queue.

Create a config file in your config/autoload folder, and replace the {{QUEUE_NAME}} with something appropriate

queue.global.php

You can configure multiple adapters and multiple queues. Multiple queues can also use the same queue adapter.

Creating job classes

A job represent the unit of work that will be processed by the queue as the queue is consumed. Create job classes by extending Dot\Queue\Job\AbstractJob.

A job must declare 2 methods

• process() - will be called when the job is processed by the queue. Do your work in here.
• failed($e) - called when the job fails(the max attempts are exceeded). It will receive the exception that caused the failure

You can also inject the job class with the needed dependencies. Use a factory class and register the job in the service container for that.

The QueueManager

The Dot\Queue\Queue\QueueManager is the main class to be injected wherever you dispatch job to a queue.

In order to create and dispatch a job

Important

• When creating jobs, always use the queue managers ->createJob(className) method. This will make sure the job is fetched from the container and will be properly initialized.

• In order to avoid serialization complication, we advice you to set only scalar or array data into the jobs' payload. This should not represent a limitation, because you can inject services into the job, that can later fetch objects from database and so on...

• Jobs already define some sane defaults for the max attempts, timeout and other job option. Override only what you need.

Consuming jobs

Run the following dotkernel command in order to start the worker loop to consume the default queue

For details on the supported command options run

Useful consumer options

• --all - consume all defined queues, in a round robin fashion
• --queues= - comma separated list of queues to consume
• --max-runtime= - run the consumer only the specified number of seconds
• --max-jobs= - run the consumer until the specified number of jobs have been processed(this includes also the failed jobs)
• --sleep= - pause the queue for the specified amount of seconds(in case the queue is empty) Check the command's help for a full list of options

In production, we advise you to use a monitoring software, such as supervisord in order to make sure that the consumer is kept alive. During development you can emulate supervisord with the npm-package called forever

Database migrations

In order to generate migrations files (to be used by Phinx library) for the jobs table and failed jobs table, two commands are provided

• $ php dot queue:jobs-table
• $ php dot queue:failed-table

Running these commands, will generate migration files with the following default options

• the namespace will be set to Data\Database\Migrations
• the table names will be jobs and failed_jobs respectively
• the path where the files will be generated data/database/migrations

You can override these options using the --namespace=, --table-name= and --path options respectively

After you have generated the files you can run

in order to create the tables

Handling failed jobs

We provide several commands to help you manage the failed jobs

• php dot queue:failed [--queue=] lists all failed jobs, or filtered by queue name
• php dot queue:flush [--queue=] remove all failed jobs, optionally filtered by queue name
• php dot queue:forget <uuid> remove the job with specified ID from the failed job list
• php dot queue:retry [<uuid>] [--queue] re-dispatch a job back into its queue, for retrying. If no ID given, retry all failed jobs or filtered by queue

@TODO - QUEUE EVENTS