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Async event dispatcher (Symfony)

The doc shows how you can setup async event dispatching in plain PHP. If you are looking for the ways to use it in Symfony application read this post instead

• Installation
• Configuration
• Dispatch event
• Process async events

Installation

You need the async dispatcher library and a one of the supported transports

$ composer require enqueue/async-event-dispatcher enqueue/fs

Configuration

<?php

// config.php

use Enqueue\AsyncEventDispatcher\AsyncListener;
use Enqueue\AsyncEventDispatcher\AsyncProcessor;
use Enqueue\AsyncEventDispatcher\PhpSerializerEventTransformer;
use Enqueue\AsyncEventDispatcher\AsyncEventDispatcher;
use Enqueue\AsyncEventDispatcher\SimpleRegistry;
use Enqueue\Fs\FsConnectionFactory;
use Symfony\Component\EventDispatcher\EventDispatcher;

require_once __DIR__.'/vendor/autoload.php';

// it could be any other queue-interop/queue-interop compatible context.
$context = (new FsConnectionFactory('file://'.__DIR__.'/queues'))->createContext();
$eventQueue = $context->createQueue('symfony_events');

$registry = new SimpleRegistry(
    ['the_event' => 'default'],
    ['default' => new PhpSerializerEventTransformer($context)]
);

$asyncListener = new AsyncListener($context, $registry, $eventQueue);

$dispatcher = new EventDispatcher();

// the listener sends even as a message through MQ
$dispatcher->addListener('the_event', $asyncListener);

$asyncDispatcher = new AsyncEventDispatcher($dispatcher, $asyncListener);

// the listener is executed on consumer side.
$asyncDispatcher->addListener('the_event', function() {
});

$asyncProcessor = new AsyncProcessor($registry, $asyncDispatcher);

Dispatch event

<?php

// send.php

use Symfony\Component\EventDispatcher\GenericEvent;

require_once __DIR__.'/vendor/autoload.php';

include __DIR__.'/config.php';

$dispatcher->dispatch('the_event', new GenericEvent('theSubject'));

Process async events

<?php

// consume.php

use Interop\Queue\Processor;

require_once __DIR__.'/vendor/autoload.php';
include __DIR__.'/config.php';

$consumer = $context->createConsumer($eventQueue);

while (true) {
    if ($message = $consumer->receive(5000)) {
        $result = $asyncProcessor->process($message, $context);

        switch ((string) $result) {
            case Processor::ACK:
                $consumer->acknowledge($message);
                break;
            case Processor::REJECT:
                $consumer->reject($message);
                break;
            case Processor::REQUEUE:
                $consumer->reject($message, true);
                break;
            default:
                throw new \LogicException('Result is not supported');
        }
    }
}

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