zdm/event-bus
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Add DeadEvent

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A dead events wraps an event that was dispatched but not delivered to
any handler. The dead event is than dispatched to dedicated handlers.
This commit is contained in:
Kai S. K. Engelbart
2021-02-19 16:04:49 +01:00
parent 4a5b94a9b7
commit 0036dc4829
4 changed files with 90 additions and 15 deletions
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34
event-bus-core/src/main/java/dev/kske/eventbus/core/EventBus.java
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@ -73,14 +73,19 @@ public final class EventBus {
var state = dispatchState.get();
state.isDispatching = true;
for (var handler : getHandlersFor(event.getClass()))
if (state.isCancelled) {
logger.log(Level.INFO, "Cancelled dispatching event {0}", event);
state.isCancelled = false;
break;
} else {
handler.execute(event);
}
Iterator<EventHandler> handlers = getHandlersFor(event.getClass());
if (handlers.hasNext()) {
while (handlers.hasNext())
if (state.isCancelled) {
logger.log(Level.INFO, "Cancelled dispatching event {0}", event);
state.isCancelled = false;
break;
} else {
handlers.next().execute(event);
}
} else if (!(event instanceof DeadEvent)) {
dispatch(new DeadEvent(this, event));
}
// Reset dispatch state
state.isDispatching = false;
@ -89,25 +94,26 @@ public final class EventBus {
}
/**
* Searches for the event handlers bound to an event class.
* Searches for the event handlers bound to an event class. This includes polymorphic handlers
* that are bound to a supertype of the event class.
*
* @param eventClass the event class to use for the search
* @return all event handlers registered for the event class
* @return an iterator over the applicable handlers in descending order of priority
* @since 0.0.1
*/
private List<EventHandler> getHandlersFor(Class<?> eventClass) {
private Iterator<EventHandler> getHandlersFor(Class<?> eventClass) {
// Get handlers defined for the event class
Set<EventHandler> handlers = bindings.getOrDefault(eventClass, new TreeSet<>());
TreeSet<EventHandler> handlers = bindings.getOrDefault(eventClass, new TreeSet<>());
// Get subtype handlers
// Get polymorphic handlers
for (var binding : bindings.entrySet())
if (binding.getKey().isAssignableFrom(eventClass))
for (var handler : binding.getValue())
if (handler.isPolymorphic())
handlers.add(handler);
return new ArrayList<>(handlers);
return handlers.iterator();
}
/**