Package alpine.event.framework

Class BaseEventService

java.lang.Object
alpine.event.framework.BaseEventService
All Implemented Interfaces:
IEventService
Direct Known Subclasses:
EventService, SingleThreadedEventService
public abstract class BaseEventService extends Object implements IEventService
A publish/subscribe (pub/sub) event service that provides the ability to publish events and asynchronously inform all subscribers to subscribed events. Defaults to a single thread event system when extending this class. This can be changed by specifying an alternative executor service.
Since:
1.0.0
Author:
Steve Springett

  • Constructor Details

    • BaseEventService

      public BaseEventService()

  • Method Details

    • setExecutorService

      protected void setExecutorService(ExecutorService executor)
      Parameters:
      executor - an ExecutorService instance
      Since:
      1.0.0

    • setLogger

      protected void setLogger(Logger logger)
      Parameters:
      logger - the logger instance to use for the executed event
      Since:
      1.0.0

    • publish

      public void publish(Event event)
      Publishes events. Published events will get dispatched to all subscribers in the order in which they subscribed. Subscribers are informed asynchronously one after the next.
      Specified by:
      publish in interface IEventService
      Parameters:
      event - An Event to publish
      Since:
      1.0.0

    • isEventBeingProcessed

      public boolean isEventBeingProcessed(ChainableEvent event)
      Determines if the specified event is currently being processed. Processing may indicate the the subscriber task is in the queue and work has not started yet, or may indicate the task is currently being executed. When this event returns false, it does not indicate completion, only that there are no subscriber tasks waiting or working on the specified event.
      Specified by:
      isEventBeingProcessed in interface IEventService
      Parameters:
      event - the event to query
      Returns:
      a boolean
      Since:
      1.4.0

    • isEventBeingProcessed

      public boolean isEventBeingProcessed(UUID chainIdentifier)
      Determines if the specified event is currently being processed. Processing may indicate the the subscriber task is in the queue and work has not started yet, or may indicate the task is currently being executed. When this event returns false, it does not indicate completion, only that there are no subscriber tasks waiting or working on the specified event.
      Specified by:
      isEventBeingProcessed in interface IEventService
      Parameters:
      chainIdentifier - the UUID of the event to query
      Returns:
      a boolean
      Since:
      1.4.0

    • subscribe

      public void subscribe(Class<? extends Event> eventType, Class<? extends Subscriber> subscriberType)
      Subscribes to an event. Subscribes are automatically notified of all events for which they are subscribed.
      Specified by:
      subscribe in interface IEventService
      Parameters:
      eventType - The type of event to subscribe to
      subscriberType - The Subscriber that gets informed when the type of event is published
      Since:
      1.0.0

    • unsubscribe

      public void unsubscribe(Class<? extends Subscriber> subscriberType)
      Unsubscribes a subscriber. All event types the subscriber has subscribed to will be unsubscribed. Once unsubscribed, the subscriber will no longer be informed of published events.
      Specified by:
      unsubscribe in interface IEventService
      Parameters:
      subscriberType - The Subscriber to unsubscribe.
      Since:
      1.0.0

    • hasSubscriptions

      public boolean hasSubscriptions(Event event)
      Determines if the specified event is able to be processed by the EventService. If a subscriber exists for the event type, this method will return true, otherwise false.
      Specified by:
      hasSubscriptions in interface IEventService
      Parameters:
      event - the event to query if subscribers exist
      Returns:
      true if the event has subscribers, false it not
      Since:
      1.2.0

    • shutdown

      public void shutdown()
      Shuts down the executioner. Once shut down, future work will not be performed. This should only be called prior to the application being shut down.
      Specified by:
      shutdown in interface IEventService
      Since:
      1.0.0

    • shutdown

      public boolean shutdown(Duration timeout)
      Shuts down this IEventService, and waits for already queued events to be processed until a given timeout elapses.

      Events enqueued during shutdown will not be processed.

      Specified by:
      shutdown in interface IEventService
      Parameters:
      timeout - The Duration to wait for event processing to complete
      Returns:
      true when all queued events were processed prior to timeout elapsing, otherwise false