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Background tasks

Some operations in Ibexa DXP don’t have to run immediately when a user clicks a button, for example, re-indexing product prices or processing bulk data. Running such operations in real time could slow down the system and disrupt the user experience.

To solve this, Ibexa DXP provides a package called Ibexa Messenger, which is an overlay to Symfony Messenger, and it's job is to queue tasks and run them in the background. Ibexa DXP sends messages (or commands) that represent the work to be done later. These messages are stored in a queue and picked up by a background worker, which ensures that resource-heavy tasks are executed at a convenient time, without putting excessive load on the system.

Ibexa Messenger supports multiple storage backends, such as Doctrine, Redis/Valkey, and PostgreSQL, and gives developers the flexibility to create their own message handlers for custom use cases.

How it works

Ibexa Messenger uses a command bus as a queue that stores messages, or commands, which tell the system what you want to happen, and separates them from the handler, which is the code that actually performs the task.

The process works as follows:

1. A message PHP object is dispatched, for example, ProductPriceReindex.
2. The message is wrapped in an envelope, which may contain additional metadata, called stamps.
3. The message is placed in the transport queue. It can be a Doctrine table, a Redis/Valkey queue, and so on.
4. A worker process continuously reads messages from the queue, pulls them into the default bus ibexa.messenger.bus and assigns them to the right handler.
5. A handler service processes the message (executes the command). You can register multiple handlers for different jobs.

Here is an example of how you can extend your code and use Ibexa Messenger to process your tasks:

Configure package

Create a config file, for example, config/packages/ibexa_messenger.yaml and define your transport:

ibexa_messenger:

    # The DSN of the transport, as expected by Symfony Messenger transport factory.
    transport_dsn:        'doctrine://default?table_name=ibexa_messenger_messages&auto_setup=false'
    deduplication_lock_storage:
        enabled:              true

        # Doctrine DBAL primary connection or custom service
        type:                 doctrine # One of "doctrine"; "custom"; "service"

        # The service ID of a custom Lock Store, if "service" type is selected
        service:              null

        # The DSN of the lock store, if "custom" type is selected
        dsn:                  null

Supported transports

You can define different transports: Ibexa Messenger has been tested to work with Redis, MySQL, PostgreSQL. For more information, see Symfony Messenger documentation or Symfony Messenger tutorial.

Start worker

Use a process manager of your choice to run the following command, or make it start together with the server:

php bin/console messenger:consume ibexa.messenger.transport --bus=ibexa.messenger.bus --siteaccess=<OPTIONAL>`

In multi-repository setups, the worker process always works for a SiteAccess that you indicate by using the --siteaccess option, therefore you may need to run multiple workers, one for each SiteAccess.

Multi-repository setups

Doctrine transport works across multiple repositories without issues, but other transports may need to be adjusted, so that queues across different repositories are not accidentally shared.

Configure for production environment

In production, make sure that Ibexa Messenger keeps running. You can configure a process manager, such as Supervisor or systemd, to restart the worker if it stops.

To prevent issues with memory leaks or stale processes, run the worker with execution limits:

• --limit limits the number of messages the worker processes before exiting.
• --time-limit limits the execution time in seconds before the worker exits.
• --memory-limit restricts the maximum memory usage.

The following example shows how you can specify these limits:

php bin/console messenger:consume ibexa.messenger.transport --bus=ibexa.messenger.bus --limit=100 --time-limit=60 --memory-limit=256M

For more information, see Symfony production recommendation for the Messenger component.

If you deploy your application on Ibexa Cloud, using Workers is recommended.

Dispatch message

To have a task processed in the background, dispatch an appropriate message by using the \Symfony\Component\Messenger\MessageBusInterfac\MessageBusInterface::dispatch() method, exactly as described in Symfony Messenger documentation:

<?php declare(strict_types=1);

namespace App\Dispatcher;

use Symfony\Component\Messenger\MessageBusInterface;

final readonly class SomeClassThatSchedulesExecutionInTheBackground
{
    public function __construct(
        private MessageBusInterface $bus,
    ) {
    }

    public function schedule(object $message): void
    {
        $this->bus->dispatch($message);
    }
}

Additionally, attach message metadata by using stamps.

Stamps

You can attach Stamps to a message envelope to add additional metadata and control how the message is processed.

Use Stamps available in Symfony, and combine them with the ones provided by Ibexa DXP:

• SudoStamp
• UserPermissionStamp

SudoStamp

SudoStamp causes the handler to use sudo mode, bypassing all permission checks when processing the message.

It's automatically attached to every dispatched message.

Caution

Starting with Ibexa DXP 5.0.9, the behavior of automatically attaching a SudoStamp to every message is deprecated and will be removed in 6.0. For messages that should be processed without taking permissions into account, always attach the SudoStamp manually to keep your code forward-compatible.

The following example shows how you can attach the SudoStamp to the message:

use Ibexa\Contracts\Messenger\Stamp\SudoStamp;
use Symfony\Component\Messenger\MessageBusInterface;

$this->bus->dispatch($message, [new SudoStamp()]);

UserPermissionStamp

UserPermissionStamp allows you to set the repository user to process the message. When the user is set, handlers execute actions on their behalf and take their permissions into account.

If you don't attach this stamp, the messages are processed by the default repository user called anonymous user. By combing this stamp with SudoStamp, you can set the repository user and skip the permission checks at the same time.

The following example shows how you can use UserPermissionStamp to preserve the current repository user after the message is dispatched.

use Ibexa\Contracts\Core\Repository\PermissionResolver;
use Ibexa\Contracts\Messenger\Stamp\UserPermissionStamp;
use Symfony\Component\Messenger\MessageBusInterface;

$currentUserId = $this->permissionResolver->getCurrentUserReference()->getUserId();
$this->bus->dispatch($message, [new UserPermissionStamp($currentUserId)]);

Extend Ibexa Messenger

Register custom message and handler

To handle additional use cases with background tasks, you can create custom message and handler class:

<?php declare(strict_types=1);

namespace App\Message;

class SomeMessage
{
    // Add properties and methods as needed for your message.
}

<?php declare(strict_types=1);

namespace App\MessageHandler;

use App\Message\SomeMessage;

final class SomeHandler
{
    public function __invoke(SomeMessage $message): void
    {
        // Handle message.
    }
}

Add a service definition to config/services.yaml and set the bus to ibexa.messenger.bus:

services:
    App\MessageHandler\SomeHandler:
        tags:
            - name: messenger.message_handler
              bus: ibexa.messenger.bus