add trigger subscription engine event bus

deptrac.yaml

@@ -149,6 +149,7 @@ deptrac:
       - Aggregate
       - Attribute
       - Clock
+      - EventBus
       - Message
       - MetadataSubscriber
       - Schema

docs/pages/event_bus.md

@@ -121,6 +121,31 @@ final class WelcomeSubscriber
     }
 }
 ```
+## Run Subscription Engine Event Bus
+
+If you want that the subscriptions run after the events are stored in the store,
+you can use the `RunSubscriptionEngineEventBus`.
+This means that a worker to run the subscriptions are not needed.
+
+```php
+use Patchlevel\EventSourcing\Subscription\Engine\RunSubscriptionEngineEventBus;
+
+/** @var SubscriptionEngine $subscriptionEngine */
+$eventBus = new RunSubscriptionEngineEventBus($subscriptionEngine);
+```
+!!! warning
+
+    You need to be careful with this event bus if you use the DoctrineStore.
+    The subsription engine do not support rollbacks.
+
+!!! note
+
+    More about the subscription engine can be found [here](subscription.md).
+
+!!! tip
+
+    You can perfectly use it in development or testing.
+
 ## Psr-14 Event Bus
 
 You can also use a [psr-14](https://www.php-fig.org/psr/psr-14/) compatible event bus.
@@ -136,6 +161,20 @@ $eventBus = new Psr14EventBus($psr14EventDispatcher);
 
     You can't use the `Subscribe` attribute with the psr-14 event bus.
 
+## Chain Event Bus
+
+You can also use a chain event bus to dispatch events to multiple event buses.
+
+```php
+use Patchlevel\EventSourcing\EventBus\ChainEventBus;
+use Patchlevel\EventSourcing\EventBus\EventBus;
+
+/**
+ * @var EventBus $eventBus1
+ * @var EventBus $eventBus2
+ */
+$eventBus = new ChainEventBus($eventBus1, $eventBus2);
+```
 ## Learn more
 
 * [How to use messages](message.md)

docs/pages/getting_started.md

@@ -275,6 +275,7 @@ use Patchlevel\EventSourcing\Repository\DefaultRepositoryManager;
 use Patchlevel\EventSourcing\Serializer\DefaultEventSerializer;
 use Patchlevel\EventSourcing\Store\DoctrineDbalStore;
 use Patchlevel\EventSourcing\Subscription\Engine\DefaultSubscriptionEngine;
+use Patchlevel\EventSourcing\Subscription\Engine\RunSubscriptionEngineEventBus;
 use Patchlevel\EventSourcing\Subscription\Store\DoctrineSubscriptionStore;
 use Patchlevel\EventSourcing\Subscription\Subscriber\MetadataSubscriberAccessorRepository;
 
@@ -311,6 +312,7 @@ $engine = new DefaultSubscriptionEngine(
 $repositoryManager = new DefaultRepositoryManager(
     $aggregateRegistry,
     $eventStore,
+    new RunSubscriptionEngineEventBus($engine),
 );
 
 $hotelRepository = $repositoryManager->get(Hotel::class);
@@ -361,7 +363,6 @@ We are now ready to use the Event Sourcing System. We can load, change and save
 ```php
 use Patchlevel\EventSourcing\Aggregate\Uuid;
 use Patchlevel\EventSourcing\Repository\Repository;
-use Patchlevel\EventSourcing\Subscription\Engine\SubscriptionEngine;
 
 $hotel1 = Hotel::create(Uuid::generate(), 'HOTEL');
 $hotel1->checkIn('David');
@@ -375,15 +376,8 @@ $hotel2 = $hotelRepository->load(Uuid::fromString('d0d0d0d0-d0d0-d0d0-d0d0-d0d0d
 $hotel2->checkIn('David');
 $hotelRepository->save($hotel2);
 
-/** @var SubscriptionEngine $engine */
-$engine->run();
-
 $hotels = $hotelProjection->getHotels();
 ```
-!!! warning
-
-    You need to run the subscription engine to update the projections and execute the processors.
-
 !!! note
 
     You can also use other forms of IDs such as uuid version 6 or a custom format. 

docs/pages/subscription.md

@@ -685,7 +685,7 @@ $catchupSubscriptionEngine = new CatchUpSubscriptionEngine($subscriptionEngine);
 
     You can use the `CatchUpSubscriptionEngine` in your tests to process the events immediately.
 
-### Throw by error Subscription Engine
+### Throw on error Subscription Engine
 
 This is another decorator for the subscription engine. It throws an exception if a subscription is in error state.
 This is useful for testing or development to get directly feedback if something is wrong.
@@ -695,13 +695,38 @@ use Patchlevel\EventSourcing\Subscription\Engine\SubscriptionEngine;
 use Patchlevel\EventSourcing\Subscription\Engine\ThrowOnErrorSubscriptionEngine;
 
 /** @var SubscriptionEngine $subscriptionStore */
-$throwByErrorSubscriptionEngine = new ThrowOnErrorSubscriptionEngine($subscriptionEngine);
+$throwOnErrorSubscriptionEngine = new ThrowOnErrorSubscriptionEngine($subscriptionEngine);
 ```
 !!! warning
 
     This is only for testing or development. Don't use it in production.
     The subscription engine has an build in retry strategy to retry subscriptions that have failed.
 
+### Run Subscription Engine after save
+
+You can trigger the subscription engine after the events are stored in the store.
+This means that a worker to run the subscriptions are not needed.
+
+```php
+use Patchlevel\EventSourcing\Subscription\Engine\RunSubscriptionEngineEventBus;
+
+/** @var SubscriptionEngine $subscriptionEngine */
+$eventBus = new RunSubscriptionEngineEventBus($subscriptionEngine);
+```
+!!! warning
+
+    You need to be careful with this event bus if you use the DoctrineStore.
+    The subsription engine do not support rollbacks.
+
+!!! note
+
+    More about repository can be found [here](./repository.md).
+    And more about event bus can be found [here](./event_bus.md).
+
+!!! tip
+
+    You can perfectly use it in development or testing.
+
 ## Usage
 
 The Subscription Engine has a few methods needed to use it effectively.

src/EventBus/ChainEventBus.php

@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\EventBus;
+
+use Patchlevel\EventSourcing\Message\Message;
+
+use function array_values;
+
+final class ChainEventBus implements EventBus
+{
+    /** @var list<EventBus> */
+    private readonly array $eventBus;
+
+    public function __construct(
+        EventBus ...$eventBus,
+    ) {
+        $this->eventBus = array_values($eventBus);
+    }
+
+    public function dispatch(Message ...$messages): void
+    {
+        foreach ($this->eventBus as $eventBus) {
+            $eventBus->dispatch(...$messages);
+        }
+    }
+}

src/Subscription/Engine/AlreadyProcessing.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\EventSourcing\Subscription\Engine;
+
+use RuntimeException;
+
+final class AlreadyProcessing extends RuntimeException
+{
+    public function __construct()
+    {
+        parent::__construct('Subscription engine is already processing');
+    }
+}