README

This middleware integrates Tactician with pmg/queue.

Installation and Usage

Install with composer.

composer require pmg/queue-tactician

To use it, add the middleware to your middleware chain somewhere before the default command handler middleware.

use League\Tactician\CommandBus;
use League\Tactician\Handler\CommandHandlerMiddleware;
use PMG\Queue\Producer;
use PMG\Queue\Tactician\QueueingMiddleware;

/** @var Producer */
$producer = createAQueueProducerSomehow();

$bus = new CommandBus([
    new QueueingMiddleware($producer),
    new CommandHandlerMiddleware(/*...*/),
]);

Enqueueing Commands

Any command that implements PMG\Queue\Message will be sent to the queue via the producer, and no further middleware will be called.

use PMG\Queue\Message;

final class DoLongRunningStuff implements Message
{
    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'LongRunningStuff';
    }
}

// goes right into the queue
$bus->handle(new DoLongRunningStuff());

Dequeueing (Consuming) Commands

To use Tactician to process messages via the consumer, use PMG\Queue\Handler\TacticianHandler.

use PMG\Queue\DefaultConsumer;
use PMG\Queue\Handler\TacticianHandler;

/** @var League\Tactician\CommandBus $bus */
$handler = new TacticianHandler($bus);

/** @var PMG\Queue\Driver $driver */
$consumer = new DefaultConsumer($driver, $handler);

$consumer->run();

The above assumes that the CommandBus instance still has the QueueingMiddleware installed. If not, you'll need to use your own handler that invokes the command bus, perhaps via CallableHandler.

use League\Tactician\CommandBus;
use League\Tactician\Handler\CommandHandlerMiddleware;
use PMG\Queue\DefaultConsumer;
use PMG\Queue\Message;
use PMG\Queue\Handler\CallableHandler;

// no QueueingMiddleware!
$differentBus = new CommandBus([
    new CommandHandlerMiddleware(/*...*/),
]);

$handler = new CallableHandler([$differentBus, 'handle']);

/** @var PMG\Queue\Driver $driver */
$consumer = new DefaultConsumer($driver, $handler);

$consumer->run();

Beware of Wrapping This Handler with PcntlForkingHandler

Because the command bus instance is shared, resources like open database connections are likely to cause issues when a child process is forked to handle messages.

Instead, create a new command bus for each message. CreatingTacticianHandler can do that for you.

use League\Tactician\CommandBus;
use League\Tactician\Handler\CommandHandlerMiddleware;
use PMG\Queue\DefaultConsumer;
use PMG\Queue\Handler\CreatingTacticianHandler;
use PMG\Queue\Tactician\QueueingMiddleware;

$handler = new CreatingTacticianHandler(function (array $_options = []) {
    // This is invoked for every message.
    return new CommandBus([
        new QueueingMiddleware(createAProducerSomehow()),
        new CommandHandlerMiddleware(/* ... */)
    ]);
});

/** @var PMG\Queue\Driver $driver */
$consumer = new DefaultConsumer($driver, $handler);

$consumer->run();