Merge pull request 'Handler Caching' (#37 ) from f/handler-caching into develop

Reviewed-on: https://git.kske.dev/zdm/event-bus/pulls/37 Reviewed-by: delvh <leon@kske.dev>
Remove print statements from test
2022-01-18 17:11:38 +01:00 · 2022-01-18 17:09:21 +01:00 · 2022-01-18 17:09:05 +01:00 · 2022-01-18 15:00:18 +01:00 · 2022-01-18 13:44:33 +01:00 · 2022-01-14 15:44:21 +01:00
45 changed files with 1663 additions and 1216 deletions
--- a/41
+++ b/41
@ -0,0 +1,41 @@
+pipeline {
+	agent any
+
+	options {
+		ansiColor('xterm')
+	}
+
+	stages {
+		stage('Build') {
+			steps {
+				sh 'mvn -DskipTests clean package'
+			}
+		}
+		stage('Test') {
+			steps {
+				sh 'mvn test'
+			}
+			post {
+				always {
+					junit '*/target/surefire-reports/*.xml'
+					publishCoverage adapters: [jacocoAdapter(mergeToOneReport: true, path: '*/target/site/jacoco/jacoco.xml')]
+				}
+			}
+		}
+		stage('SonarQube Analysis') {
+			when {
+				branch 'develop'
+			}
+			steps {
+				withSonarQubeEnv('KSKE SonarQube') {
+					sh 'mvn sonar:sonar'
+				}
+			}
+		}
+	}
+	post {
+		success {
+			archiveArtifacts artifacts: '*/target/event-bus-*.jar'
+		}
+	}
+}
--- a/681
+++ b/681
@ -1,674 +1,13 @@
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-License will continue to apply to the part which is the covered work,
-but the special requirements of the GNU Affero General Public License,
-section 13, concerning interaction through a network will apply to the
-combination as such.
-
-  14. Revised Versions of this License.
-
-  The Free Software Foundation may publish revised and/or new versions of
-the GNU General Public License from time to time.  Such new versions will
-be similar in spirit to the present version, but may differ in detail to
-address new problems or concerns.
-
-  Each version is given a distinguishing version number.  If the
-Program specifies that a certain numbered version of the GNU General
-Public License "or any later version" applies to it, you have the
-option of following the terms and conditions either of that numbered
-version or of any later version published by the Free Software
-Foundation.  If the Program does not specify a version number of the
-GNU General Public License, you may choose any version ever published
-by the Free Software Foundation.
-
-  If the Program specifies that a proxy can decide which future
-versions of the GNU General Public License can be used, that proxy's
-public statement of acceptance of a version permanently authorizes you
-to choose that version for the Program.
-
-  Later license versions may give you additional or different
-permissions.  However, no additional obligations are imposed on any
-author or copyright holder as a result of your choosing to follow a
-later version.
-
-  15. Disclaimer of Warranty.
-
-  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
-APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
-HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
-OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
-THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
-IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
-ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
-
-  16. Limitation of Liability.
-
-  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
-WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
-THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
-GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
-USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
-DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
-PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
-EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
-SUCH DAMAGES.
-
-  17. Interpretation of Sections 15 and 16.
-
-  If the disclaimer of warranty and limitation of liability provided
-above cannot be given local legal effect according to their terms,
-reviewing courts shall apply local law that most closely approximates
-an absolute waiver of all civil liability in connection with the
-Program, unless a warranty or assumption of liability accompanies a
-copy of the Program in return for a fee.
-
-                     END OF TERMS AND CONDITIONS
-
-            How to Apply These Terms to Your New Programs
-
-  If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these terms.
-
-  To do so, attach the following notices to the program.  It is safest
-to attach them to the start of each source file to most effectively
-state the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
-
-    <one line to give the program's name and a brief idea of what it does.>
-    Copyright (C) <year>  <name of author>
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-Also add information on how to contact you by electronic and paper mail.
-
-  If the program does terminal interaction, make it output a short
-notice like this when it starts in an interactive mode:
-
-    <program>  Copyright (C) <year>  <name of author>
-    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-    This is free software, and you are welcome to redistribute it
-    under certain conditions; type `show c' for details.
-
-The hypothetical commands `show w' and `show c' should show the appropriate
-parts of the General Public License.  Of course, your program's commands
-might be different; for a GUI interface, you would use an "about box".
-
-  You should also get your employer (if you work as a programmer) or school,
-if any, to sign a "copyright disclaimer" for the program, if necessary.
-For more information on this, and how to apply and follow the GNU GPL, see
-<http://www.gnu.org/licenses/>.
-
-  The GNU General Public License does not permit incorporating your program
-into proprietary programs.  If your program is a subroutine library, you
-may consider it more useful to permit linking proprietary applications with
-the library.  If this is what you want to do, use the GNU Lesser General
-Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
--- a/README.md
+++ b/README.md
@ -45,9 +45,6 @@ public class SimpleEventListener {
 }
 ```

-In this case, an event bus is created and used locally.
-In a more sophisticated example the class would acquire an external event bus that is used by multiple classes.
-
 Note that creating static event handlers like this

 ```java
@ -57,6 +54,33 @@ private static void onSimpleEvent(SimpleEvent event) { ... }

 is technically possible, however you would still have to create an instance of the event listener to register it at an event bus.

+## Installation
+
+Event Bus is available in Maven Central.
+To include it inside your project, just add the following dependency to your `pom.xml`:
+
+```xml
+<dependencies>
+    <dependency>
+        <groupId>dev.kske</groupId>
+        <artifactId>event-bus-core</artifactId>
+        <version>1.2.0</version>
+    </dependency>
+</dependencies>
+```
+
+Then, require the Event Bus Core module in your `module-info.java`:
+
+```java
+requires dev.kske.eventbus.core;
+```
+
+If you intend to use event handlers that are inaccessible to Event Bus by means of Java language access control, make sure to allow reflective access to your package for Event Bus:
+
+```java
+opens my.package to dev.kske.eventbus.core;
+```
+
 ## Polymorphic Event Handlers

 On certain occasions it's practical for an event handler to accept both events of the specified type, as well as subclasses of that event.
@ -97,6 +121,25 @@ private void onSimpleEvent() {

 Make sure that you **do not** both declare a parameter and specify the event type in the annotation, as this would be ambiguous.

+## Callback listeners
+
+While defining event handlers as annotated methods is rather simple and readable, sometimes a more flexible approach is required.
+For this reason, there are callback event handlers that allow the registration of an "inline" event listener consisting of just one handler in the form of a consumer:
+
+```java
+EventBus.getInstance().registerListener(SimpleEvent.class, e -> System.out.println("Received " + e));
+```
+
+The event type has to be defined explicitly, with the priority and polymorphism parameters being optional.
+If you intend to remove the listener later, remember to keep a reference to it, as you would have to clear the entire event bus if you didn't.
+
+## Listener-Level Properties
+
+When defining a dedicated event listener that, for example, performs pre- or post-processing, all event handlers will probably have the same non-standard priority.
+Instead of defining that priority for each handler, it can be defined at the listener level by annotating the listener itself.
+
+The same applies to polymorphism.
+
 ## Event Consumption

 In some cases it might be useful to stop the propagation of an event.
@ -123,32 +166,80 @@ This applies to all event handlers that would have been executed after the one c
 Avoid cancelling events while using multiple event handlers with the same priority.
 As event handlers are ordered by priority, it is not defined which of them will be executed after the event has been consumed.

-## Installation
+## System Events

-Event Bus is available in Maven Central.
-To include it inside your project, just add the following dependency to your `pom.xml`:
+To accommodate for special circumstances in an event distribution, system events have been introduced.
+At the moment, there are two system events, which are explained in this section.

-```xml
-<dependencies>
-    <dependency>
-        <groupId>dev.kske</groupId>
-        <artifactId>event-bus-core</artifactId>
-        <version>1.0.0</version>
-    </dependency>
-</dependencies>
-```
+### Detecting Unhandled Events

-Then, require the Event Bus Core module in your `module-info.java`:
+When an event is dispatched but not delivered to any handler, a dead event is dispatched that wraps the original event.
+You can declare a dead event handler to respond to this situation:

 ```java
-requires dev.kske.eventbus.core;
+private void onDeadEvent(DeadEvent deadEvent) { ... }
 ```

-If you intend to use event handlers that are inaccessible to Event Bus by means of Java language access control, make sure to allow reflective access from your module:
+### Detecting Exceptions Thrown by Event Handlers
+
+When an event handler throws an exception, an exception event is dispatched that wraps the original event.
+An exception handler is declared as follows:

 ```java
-opens my.module to dev.kske.eventbus.core;
+private void onExceptionEvent(ExceptionEvent ExceptionEvent) { ... }
 ```
+Both system events reference the event bus that caused them and a warning is logged if they are unhandled.
+
+#### Yeeting Exceptions Out of an Event Handler
+
+In some cases, a warning about an `Exception` that was thrown in an event handler is not enough, stays unnoticed, or an exception should be catched explicitly.
+Event Bus explicitly dispatches no `ExceptionEvent` when an `ExceptionWrapper` exception is thrown and instead simply rethrows it.
+`ExceptionWrapper` is an unchecked exception that (as the name says) simply wraps an exception that caused it.
+This means the following is possible and results in a normal program exit:
+```java
+@Event(String.class)
+void onString() {
+	throw new ExceptionWrapper(new RuntimeException("I failed!"));
+}
+
+void helloStackTrace() {
+	EventBus.getInstance().registerListener(this);
+	try {
+		EventBus.getInstance().dispatch("A string!");
+		System.exit(-1);
+	} catch(ExceptionWrapper e) {
+		e.getCause().printStackTrace();
+		System.exit(0);
+	}
+}
+```
+
+### What About Endless Recursion Caused By Dead Events and Exception Events?
+
+As one might imagine, an unhandled dead event would theoretically lead to an endless recursion.
+The same applies when an exception event handler throws an exception.
+
+To avoid this, system events never cause system events and instead just issue a warning to the logger.
+
+## Inheritance
+
+When a superclass or an interface of an event listener defines event handlers, they will be detected and registered by Event Bus, even if they are `private`.
+If an event handler is overridden by the listener, the `@Event` annotation of the overridden method is automatically considered present on the overriding method.
+If the overridden method already contains an implementation in the superclass, the superclass implementation is ignored as expected.
+
+The `@Priority` and `@Polymorphic` annotations are inherited both on a class and on a method level.
+If the priority or polymorphism has to be redefined on an inherited handler, the `@Event` annotation has to be added explicitly.
+
+## Debugging
+
+In more complex setups, taking a look at the event handler execution order can be helpful for debugging.
+Event Bus offers a method for this purpose which can be used as follows:
+
+```java
+System.out.println(EventBus.getInstance().debugExecutionOrder(SimpleEvent.class));
+```
+
+Then, the execution order can be inspected in the console.

 ## Compile-Time Error Checking with Event Bus Proc

@ -169,7 +260,7 @@ When using Maven, it can be registered using the Maven Compiler Plugin:
            <annotationProcessorPath>
                <groupId>dev.kske</groupId>
                <artifactId>event-bus-proc</artifactId>
-                <version>1.0.0</version>
+                <version>1.2.0</version>
            </annotationProcessorPath>
        </annotationProcessorPaths>
    </configuration>
--- a/event-bus-core/.classpath
+++ b/event-bus-core/.classpath
--- a/event-bus-core/.project
+++ b/event-bus-core/.project
--- a/core/pom.xml
+++ b/core/pom.xml
@ -0,0 +1,66 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<artifactId>event-bus-core</artifactId>
+	<name>Event Bus Core</name>
+
+	<parent>
+		<groupId>dev.kske</groupId>
+		<artifactId>event-bus</artifactId>
+		<version>1.2.0</version>
+	</parent>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-api</artifactId>
+			<version>5.8.1</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+
+		<!-- Disable resource folder -->
+		<resources />
+
+		<plugins>
+
+			<!-- Run unit tests -->
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-surefire-plugin</artifactId>
+				<version>3.0.0-M5</version>
+				<configuration>
+					<argLine>
+						${argLine}
+						--add-opens dev.kske.eventbus.core/dev.kske.eventbus.core=ALL-UNNAMED
+						--add-opens dev.kske.eventbus.core/dev.kske.eventbus.core.handler=ALL-UNNAMED
+					</argLine>
+				</configuration>
+			</plugin>
+
+			<!-- Generate coverage report -->
+			<plugin>
+				<groupId>org.jacoco</groupId>
+				<artifactId>jacoco-maven-plugin</artifactId>
+				<version>0.8.7</version>
+				<executions>
+					<execution>
+						<goals>
+							<goal>prepare-agent</goal>
+						</goals>
+					</execution>
+					<execution>
+						<id>report</id>
+						<phase>test</phase>
+						<goals>
+							<goal>report</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
+
+		</plugins>
+	</build>
+</project>
--- a/core/src/main/java/dev/kske/eventbus/core/DeadEvent.java
+++ b/core/src/main/java/dev/kske/eventbus/core/DeadEvent.java
@ -0,0 +1,37 @@
+package dev.kske.eventbus.core;
+
+/**
+ * Wraps an event that was dispatched but for which no handler has been bound.
+ * <p>
+ * Handling dead events is useful as it can identify a poorly configured event distribution.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.1.0
+ */
+public final class DeadEvent {
+
+	private final EventBus	eventBus;
+	private final Object	event;
+
+	DeadEvent(EventBus eventBus, Object event) {
+		this.eventBus	= eventBus;
+		this.event		= event;
+	}
+
+	@Override
+	public String toString() {
+		return String.format("DeadEvent[eventBus=%s, event=%s]", eventBus, event);
+	}
+
+	/**
+	 * @return the event bus that dispatched this event
+	 * @since 1.1.0
+	 */
+	public EventBus getEventBus() { return eventBus; }
+
+	/**
+	 * @return the event that could not be delivered
+	 * @since 1.1.0
+	 */
+	public Object getEvent() { return event; }
+}
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/Event.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/Event.java
@ -22,7 +22,7 @@ import java.lang.annotation.*;
 public @interface Event {

 	/**
-	 * Defines the event type the handler listens to. If this value is set, the handler is not
+	 * Defines the event type the handler listens for. If this value is set, the handler is not
 	 * allowed to declare parameters.
 	 * <p>
 	 * This is useful when the event handler does not utilize the event instance.
@ -30,13 +30,5 @@ public @interface Event {
 	 * @return the event type accepted by the handler
 	 * @since 1.0.0
 	 */
-	Class<?> value() default USE_PARAMETER.class;
-
-	/**
-	 * Signifies that the event type the handler listens to is determined by the type of its only
-	 * parameter.
-	 *
-	 * @since 0.0.3
-	 */
-	static final class USE_PARAMETER {}
+	Class<?> value() default void.class;
 }
--- a/core/src/main/java/dev/kske/eventbus/core/EventBus.java
+++ b/core/src/main/java/dev/kske/eventbus/core/EventBus.java
@ -0,0 +1,503 @@
+package dev.kske.eventbus.core;
+
+import java.lang.System.Logger;
+import java.lang.System.Logger.Level;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.*;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Consumer;
+
+import dev.kske.eventbus.core.handler.*;
+
+/**
+ * Event listeners can be registered at an event bus to be notified when an event is dispatched.
+ * <p>
+ * A singleton instance of this class can be lazily created and acquired using the
+ * {@link EventBus#getInstance()} method.
+ *
+ * @implNote This is a thread-safe implementation.
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ * @see Event
+ */
+public final class EventBus {
+
+	/**
+	 * Holds the state of the dispatching process on one thread.
+	 *
+	 * @since 0.1.0
+	 */
+	private static final class DispatchState {
+
+		/**
+		 * Indicates that the last event handler invoked has called {@link EventBus#cancel}. In that
+		 * case, the event is not dispatched further.
+		 *
+		 * @since 0.1.0
+		 */
+		boolean isCancelled;
+
+		/**
+		 * Is incremented when {@link EventBus#dispatch(Object)} is invoked and decremented when it
+		 * finishes. This allows keeping track of nested dispatches.
+		 *
+		 * @since 1.2.0
+		 */
+		int nestingCount;
+	}
+
+	/**
+	 * The priority assigned to every event handler without an explicitly defined priority.
+	 *
+	 * @since 1.1.0
+	 * @see Priority
+	 */
+	public static final int DEFAULT_PRIORITY = 100;
+
+	private static final EventBus singletonInstance = new EventBus();
+
+	private static final Logger logger = System.getLogger(EventBus.class.getName());
+
+	/**
+	 * Compares event handlers based on priority, but uses hash codes for equal priorities.
+	 *
+	 * @implNote As the priority comparator by itself is not consistent with equals (two handlers
+	 *           with the same priority are not necessarily equal, but would have a comparison
+	 *           result of 0), the hash code is used for the fallback comparison. This way,
+	 *           consistency with equals is restored.
+	 * @since 1.2.0
+	 */
+	private static final Comparator<EventHandler> byPriority =
+		Comparator.comparingInt(EventHandler::getPriority).reversed()
+			.thenComparingInt(EventHandler::hashCode);
+
+	/**
+	 * Returns the default event bus, which is a statically initialized singleton instance.
+	 *
+	 * @return the default event bus
+	 * @since 0.0.2
+	 */
+	public static EventBus getInstance() {
+		return singletonInstance;
+	}
+
+	/**
+	 * Event handler bindings (target class to handlers registered for that class), does not contain
+	 * other (polymorphic) handlers.
+	 *
+	 * @since 0.0.1
+	 */
+	private final Map<Class<?>, TreeSet<EventHandler>> bindings = new ConcurrentHashMap<>();
+
+	/**
+	 * A cache mapping an event class to all handlers the event should be dispatched to. This
+	 * includes polymorphic handlers that don't reference the event class explicitly. If an event
+	 * class is not contained inside this cache, the {@link #bindings} have to be traversed manually
+	 * in search of applicable handlers.
+	 *
+	 * @since 1.3.0
+	 */
+	private final Map<Class<?>, TreeSet<EventHandler>> bindingCache = new ConcurrentHashMap<>();
+
+	/**
+	 * Stores all registered event listeners (which declare event handlers) and prevents them from
+	 * being garbage collected.
+	 *
+	 * @since 0.0.1
+	 */
+	private final Set<Object> registeredListeners = ConcurrentHashMap.newKeySet();
+
+	/**
+	 * The current event dispatching state, local to each thread.
+	 *
+	 * @since 0.1.0
+	 */
+	private final ThreadLocal<DispatchState> dispatchState =
+		ThreadLocal.withInitial(DispatchState::new);
+
+	/**
+	 * Dispatches an event to all event handlers registered for it in descending order of their
+	 * priority.
+	 *
+	 * @param event the event to dispatch
+	 * @throws EventBusException    if an event handler isn't accessible or has an invalid signature
+	 * @throws ExceptionWrapper     if it is thrown by an event handler
+	 * @throws NullPointerException if the specified event is {@code null}
+	 * @since 0.0.1
+	 */
+	public void dispatch(Object event) {
+		Objects.requireNonNull(event);
+		logger.log(Level.INFO, "Dispatching event {0}", event);
+
+		// Look up dispatch state
+		var state = dispatchState.get();
+
+		// Increment nesting count (becomes > 1 during nested dispatches)
+		++state.nestingCount;
+
+		Iterator<EventHandler> handlers = getHandlersFor(event.getClass()).iterator();
+		if (handlers.hasNext()) {
+			while (handlers.hasNext())
+				if (state.isCancelled) {
+					logger.log(Level.INFO, "Cancelled dispatching event {0}", event);
+					state.isCancelled = false;
+					break;
+				} else {
+					try {
+						handlers.next().execute(event);
+					} catch (InvocationTargetException e) {
+						if (e.getCause() instanceof Error)
+
+							// Transparently pass error to the caller
+							throw (Error) e.getCause();
+						else if (e.getCause() instanceof ExceptionWrapper)
+
+							// Transparently pass exception wrapper to the caller
+							throw (ExceptionWrapper) e.getCause();
+						else if (event instanceof DeadEvent || event instanceof ExceptionEvent)
+
+							// Warn about system event not being handled
+							logger.log(Level.WARNING, event + " not handled due to exception", e);
+						else
+
+							// Dispatch exception event
+							dispatch(new ExceptionEvent(this, event, e.getCause()));
+					}
+				}
+		} else if (event instanceof DeadEvent || event instanceof ExceptionEvent) {
+
+			// Warn about the dead event not being handled
+			logger.log(Level.WARNING, "{0} not handled", event);
+		} else {
+
+			// Dispatch dead event
+			dispatch(new DeadEvent(this, event));
+		}
+
+		// Decrement nesting count (becomes 0 when all dispatches on the thread are finished)
+		--state.nestingCount;
+
+		logger.log(Level.DEBUG, "Finished dispatching event {0}", event);
+	}
+
+	/**
+	 * Searches for the event handlers bound to an event class. This includes polymorphic handlers
+	 * that are bound to a supertype of the event class.
+	 *
+	 * @implNote If the given event type was requested in the past, the handlers are retrieved from
+	 *           the {@link #bindingCache}. If not, the entire {@link #bindings} are traversed in
+	 *           search of polymorphic handlers compatible with the event type.
+	 * @param eventType the event type to use for the search
+	 * @return a navigable set containing the applicable handlers in descending order of priority
+	 * @since 1.2.0
+	 */
+	private NavigableSet<EventHandler> getHandlersFor(Class<?> eventType) {
+		return bindingCache.computeIfAbsent(eventType, k -> {
+
+			// Get handlers defined for the event class
+			TreeSet<EventHandler> handlers =
+				bindings.getOrDefault(eventType, new TreeSet<>(byPriority));
+
+			// Get polymorphic handlers
+			for (var binding : bindings.entrySet())
+				if (binding.getKey().isAssignableFrom(eventType))
+					for (var handler : binding.getValue())
+						if (handler.isPolymorphic())
+							handlers.add(handler);
+
+			return handlers;
+		});
+	}
+
+	/**
+	 * Cancels an event that is currently dispatched from inside an event handler.
+	 *
+	 * @throws EventBusException if the calling thread is not an active dispatching thread
+	 * @since 0.1.0
+	 */
+	public void cancel() {
+		var state = dispatchState.get();
+		if (state.nestingCount > 0 && !state.isCancelled)
+			state.isCancelled = true;
+		else
+			throw new EventBusException("Calling thread not an active dispatching thread!");
+	}
+
+	/**
+	 * Registers an event listener at this event bus.
+	 *
+	 * @param listener the listener to register
+	 * @throws EventBusException    if the listener is already registered or a declared event
+	 *                              handler does not comply with the specification
+	 * @throws NullPointerException if the specified listener is {@code null}
+	 * @since 0.0.1
+	 * @see Event
+	 */
+	public void registerListener(Object listener) {
+		Objects.requireNonNull(listener);
+		if (registeredListeners.contains(listener))
+			throw new EventBusException(listener + " already registered!");
+		logger.log(Level.INFO, "Registering event listener {0}", listener.getClass().getName());
+		boolean handlerBound = false;
+
+		// Predefined handler polymorphism
+		boolean polymorphic = false;
+		if (listener.getClass().isAnnotationPresent(Polymorphic.class))
+			polymorphic = listener.getClass().getAnnotation(Polymorphic.class).value();
+
+		// Predefined handler priority
+		int priority = DEFAULT_PRIORITY;
+		if (listener.getClass().isAnnotationPresent(Priority.class))
+			priority = listener.getClass().getAnnotation(Priority.class).value();
+
+		registeredListeners.add(listener);
+		for (var method : getHandlerMethods(listener.getClass())) {
+			Event annotation = method.getAnnotation(Event.class);
+
+			// Skip methods without annotations
+			if (annotation == null)
+				continue;
+
+			// Initialize and bind the handler
+			bindHandler(
+				new ReflectiveEventHandler(listener, method, annotation, polymorphic, priority));
+			handlerBound = true;
+		}
+
+		if (!handlerBound)
+			logger.log(
+				Level.WARNING,
+				"No event handlers bound for event listener {0}",
+				listener.getClass().getName());
+	}
+
+	/**
+	 * Searches for event handling methods declared inside the inheritance hierarchy of an event
+	 * listener.
+	 *
+	 * @param listenerClass the class to inspect
+	 * @return all event handling methods defined for the given listener
+	 * @since 1.3.0
+	 */
+	private Set<Method> getHandlerMethods(Class<?> listenerClass) {
+
+		// Get methods declared by the listener
+		Set<Method> methods = getMethodsAnnotatedWith(listenerClass, Event.class);
+
+		// Recursively add superclass handlers
+		Class<?> superClass = listenerClass.getSuperclass();
+		if (superClass != null && superClass != Object.class)
+			methods.addAll(getHandlerMethods(superClass));
+
+		// Recursively add interface handlers
+		for (Class<?> iClass : listenerClass.getInterfaces())
+			methods.addAll(getHandlerMethods(iClass));
+
+		return methods;
+	}
+
+	/**
+	 * Searches for declared methods with a specific annotation inside a class.
+	 *
+	 * @param enclosingClass  the class to inspect
+	 * @param annotationClass the annotation to look for
+	 * @return all methods matching the search criteria
+	 * @since 1.3.0
+	 */
+	private Set<Method> getMethodsAnnotatedWith(Class<?> enclosingClass,
+		Class<? extends Annotation> annotationClass) {
+		var methods = new HashSet<Method>();
+		for (var method : enclosingClass.getDeclaredMethods())
+			if (method.isAnnotationPresent(annotationClass))
+				methods.add(method);
+
+		return methods;
+	}
+
+	/**
+	 * Registers a callback listener, which is a consumer that is invoked when an event occurs. The
+	 * listener is not polymorphic and has the {@link #DEFAULT_PRIORITY}.
+	 *
+	 * @param <E>           the event type the listener listens for
+	 * @param eventType     the event type the listener listens for
+	 * @param eventListener the callback that is invoked when an event occurs
+	 * @since 1.2.0
+	 * @see #registerListener(Class, Consumer, boolean, int)
+	 */
+	public <E> void registerListener(Class<E> eventType, Consumer<E> eventListener) {
+		registerListener(eventType, eventListener, false, DEFAULT_PRIORITY);
+	}
+
+	/**
+	 * Registers a callback listener, which is a consumer that is invoked when an event occurs. The
+	 * listener has the {@link #DEFAULT_PRIORITY}.
+	 *
+	 * @param <E>           the event type the listener listens for
+	 * @param eventType     the event type the listener listens for
+	 * @param eventListener the callback that is invoked when an event occurs
+	 * @param polymorphic   whether the listener is also invoked for subtypes of the event type
+	 * @since 1.2.0
+	 * @see #registerListener(Class, Consumer, boolean, int)
+	 */
+	public <E> void registerListener(Class<E> eventType, Consumer<E> eventListener,
+		boolean polymorphic) {
+		registerListener(eventType, eventListener, polymorphic, DEFAULT_PRIORITY);
+	}
+
+	/**
+	 * Registers a callback listener, which is a consumer that is invoked when an event occurs. The
+	 * listener is not polymorphic.
+	 *
+	 * @param <E>           the event type the listener listens for
+	 * @param eventType     the event type the listener listens for
+	 * @param eventListener the callback that is invoked when an event occurs
+	 * @param priority      the priority to assign to the listener
+	 * @since 1.2.0
+	 * @see #registerListener(Class, Consumer, boolean, int)
+	 */
+	public <E> void registerListener(Class<E> eventType, Consumer<E> eventListener, int priority) {
+		registerListener(eventType, eventListener, false, priority);
+	}
+
+	/**
+	 * Registers a callback listener, which is a consumer that is invoked when an event occurs.
+	 *
+	 * @param <E>           the event type the listener listens for
+	 * @param eventType     the event type the listener listens for
+	 * @param eventListener the callback that is invoked when an event occurs
+	 * @param polymorphic   whether the listener is also invoked for subtypes of the event type
+	 * @param priority      the priority to assign to the listener
+	 * @since 1.2.0
+	 */
+	public <E> void registerListener(Class<E> eventType, Consumer<E> eventListener,
+		boolean polymorphic,
+		int priority) {
+		Objects.requireNonNull(eventListener);
+		if (registeredListeners.contains(eventListener))
+			throw new EventBusException(eventListener + " already registered!");
+		logger.log(Level.INFO, "Registering callback event listener {0}",
+			eventListener.getClass().getName());
+
+		registeredListeners.add(eventListener);
+		bindHandler(new CallbackEventHandler(eventType, eventListener, polymorphic, priority));
+	}
+
+	/**
+	 * Inserts a new handler into the {@link #bindings} map. Additionally, the handler is placed
+	 * inside the {@link #bindingCache} where applicable.
+	 *
+	 * @param handler the handler to bind
+	 * @since 1.2.0
+	 */
+	private void bindHandler(EventHandler handler) {
+
+		// Bind handler
+		logger.log(Level.DEBUG, "Binding event handler {0}", handler);
+		bindings.computeIfAbsent(handler.getEventType(), k -> new TreeSet<>(byPriority))
+			.add(handler);
+
+		// Insert handler into cache
+		bindingCache.computeIfAbsent(handler.getEventType(), k -> new TreeSet<>(byPriority))
+			.add(handler);
+
+		// Handler is polymorphic => insert where applicable
+		if (handler.isPolymorphic())
+			for (var binding : bindingCache.entrySet())
+				if (binding.getKey().isAssignableFrom(handler.getEventType()))
+					binding.getValue().add(handler);
+	}
+
+	/**
+	 * Removes a specific listener from this event bus.
+	 *
+	 * @param listener the listener to remove
+	 * @since 0.0.1
+	 */
+	public void removeListener(Object listener) {
+		Objects.requireNonNull(listener);
+		logger.log(Level.INFO, "Removing event listener {0}", listener.getClass().getName());
+
+		// Remove bindings from binding map
+		for (var binding : bindings.values()) {
+			var it = binding.iterator();
+			while (it.hasNext()) {
+				var handler = it.next();
+				if (handler.getListener().equals(listener)) {
+					logger.log(Level.DEBUG, "Unbinding event handler {0}", handler);
+					it.remove();
+				}
+			}
+		}
+
+		// Remove bindings from cache
+		for (var binding : bindingCache.values()) {
+			var it = binding.iterator();
+			while (it.hasNext()) {
+				var handler = it.next();
+				if (handler.getListener().equals(listener)) {
+					logger.log(Level.TRACE, "Removing event handler {0} from cache", handler);
+					it.remove();
+				}
+			}
+		}
+
+		// Remove the listener itself
+		registeredListeners.remove(listener);
+	}
+
+	/**
+	 * Removes all event listeners from this event bus.
+	 *
+	 * @since 0.0.1
+	 */
+	public void clearListeners() {
+		logger.log(Level.INFO, "Clearing event listeners");
+		bindings.clear();
+		bindingCache.clear();
+		registeredListeners.clear();
+	}
+
+	/**
+	 * Generates a string describing the event handlers that would be executed for a specific event
+	 * type, in order and without actually executing them.
+	 *
+	 * @apiNote Using this method is only recommended for debugging purposes, as the output depends
+	 *          on implementation internals which may be subject to change.
+	 * @implNote Nested dispatches are not accounted for, as this would require actually executing
+	 *           the handlers.
+	 * @param eventType the event type to generate the execution order for
+	 * @return a human-readable event handler list suitable for debugging purposes
+	 * @since 1.2.0
+	 */
+	public String debugExecutionOrder(Class<?> eventType) {
+		var	handlers	= getHandlersFor(eventType);
+		var	sj			= new StringJoiner("\n");
+
+		// Output header line
+		sj.add(String.format("Event handler execution order for %s (%d handler(s)):", eventType,
+			handlers.size()));
+		sj.add(
+			"==========================================================================================");
+
+		// Individual handlers
+		for (var handler : handlers)
+			sj.add(handler.toString());
+
+		// Bottom line
+		sj.add(
+			"==========================================================================================");
+
+		return sj.toString();
+	}
+
+	/**
+	 * Provides an unmodifiable view of the event listeners registered at this event bus.
+	 *
+	 * @return all registered event listeners
+	 * @since 0.0.1
+	 */
+	public Set<Object> getRegisteredListeners() {
+		return Collections.unmodifiableSet(registeredListeners);
+	}
+}
--- a/core/src/main/java/dev/kske/eventbus/core/EventBusException.java
+++ b/core/src/main/java/dev/kske/eventbus/core/EventBusException.java
@ -0,0 +1,39 @@
+package dev.kske.eventbus.core;
+
+/**
+ * This unchecked exception is specific to the event bus and can be thrown under the following
+ * circumstances:
+ * <ul>
+ * <li>An event handler throws an exception (which is stored as the cause)</li>
+ * <li>An event listener with an invalid event handler is registered</li>
+ * <li>{@link EventBus#cancel()} is invoked from outside an active dispatch thread</li>
+ * </ul>
+ *
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ */
+public final class EventBusException extends RuntimeException {
+
+	private static final long serialVersionUID = 7254445250300604449L;
+
+	/**
+	 * Creates a new event bus exception.
+	 *
+	 * @param message the message to display
+	 * @param cause   the cause of this exception
+	 * @since 0.0.1
+	 */
+	public EventBusException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	/**
+	 * Creates a new event bus exception.
+	 *
+	 * @param message the message to display
+	 * @since 0.0.1
+	 */
+	public EventBusException(String message) {
+		super(message);
+	}
+}
--- a/core/src/main/java/dev/kske/eventbus/core/ExceptionEvent.java
+++ b/core/src/main/java/dev/kske/eventbus/core/ExceptionEvent.java
@ -0,0 +1,47 @@
+package dev.kske.eventbus.core;
+
+/**
+ * Wraps an event that was dispatched but caused an exception in one of its handlers.
+ * <p>
+ * Handling exception events is useful as it allows the creation of a centralized exception handling
+ * mechanism for unexpected exceptions.
+ * 
+ * @author Kai S. K. Engelbart
+ * @since 1.1.0
+ */
+public final class ExceptionEvent {
+
+	private final EventBus	eventBus;
+	private final Object	event;
+	private final Throwable	cause;
+
+	ExceptionEvent(EventBus eventBus, Object event, Throwable cause) {
+		this.eventBus	= eventBus;
+		this.event		= event;
+		this.cause		= cause;
+	}
+
+	@Override
+	public String toString() {
+		return String.format("ExceptionEvent[eventBus=%s, event=%s, cause=%s]", eventBus, event,
+			cause);
+	}
+
+	/**
+	 * @return the event bus that dispatched this event
+	 * @since 1.1.0
+	 */
+	public EventBus getEventBus() { return eventBus; }
+
+	/**
+	 * @return the event that could not be handled because of an exception
+	 * @since 1.1.0
+	 */
+	public Object getEvent() { return event; }
+
+	/**
+	 * @return the exception that was thrown while handling the event
+	 * @since 1.1.0
+	 */
+	public Throwable getCause() { return cause; }
+}
--- a/core/src/main/java/dev/kske/eventbus/core/ExceptionWrapper.java
+++ b/core/src/main/java/dev/kske/eventbus/core/ExceptionWrapper.java
@ -0,0 +1,24 @@
+package dev.kske.eventbus.core;
+
+/**
+ * This unchecked exception acts as a wrapper for an arbitrary exception to prevent an
+ * {@link ExceptionEvent} from being dispatched. Instead, the wrapped exception is rethrown by
+ * {@link EventBus#dispatch(Object)}.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.1
+ */
+public final class ExceptionWrapper extends RuntimeException {
+
+	private static final long serialVersionUID = -2016681140617308788L;
+
+	/**
+	 * Creates a new exception wrapper.
+	 *
+	 * @param cause the exception to wrap
+	 * @since 1.2.1
+	 */
+	public ExceptionWrapper(Exception cause) {
+		super(cause);
+	}
+}
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/Polymorphic.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/Polymorphic.java
@ -1,6 +1,6 @@
 package dev.kske.eventbus.core;

-import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.*;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;

 import java.lang.annotation.*;
@ -8,6 +8,9 @@ import java.lang.annotation.*;
 /**
 * Allows an event handler to receive events that are subtypes of the declared event type.
 * <p>
+ * When used on a type, the value applies to all event handlers declared within that type that don't
+ * define a value on their own.
+ * <p>
 * This is useful when defining an event handler for an interface or an abstract class.
 *
 * @author Kai S. K. Engelbart
@ -15,6 +18,14 @@ import java.lang.annotation.*;
 * @see Event
 */
@Documented
+@Inherited
@Retention(RUNTIME)
-@Target(METHOD)
-public @interface Polymorphic {}
+@Target({ METHOD, TYPE })
+public @interface Polymorphic {
+
+	/**
+	 * @return whether the event handler is polymorphic
+	 * @since 1.1.0
+	 */
+	boolean value() default true;
+}
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/Priority.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/Priority.java
@ -1,6 +1,6 @@
 package dev.kske.eventbus.core;

-import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.*;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;

 import java.lang.annotation.*;
@ -9,6 +9,9 @@ import java.lang.annotation.*;
 * Defines the priority of an event handler. Handlers are executed in descending order of their
 * priority.
 * <p>
+ * When used on a type, the value applies to all event handlers declared within that type that don't
+ * define a value on their own.
+ * <p>
 * Handlers without this annotation have the default priority of 100.
 * <p>
 * The execution order of handlers with the same priority is undefined.
@ -18,8 +21,9 @@ import java.lang.annotation.*;
 * @see Event
 */
@Documented
+@Inherited
@Retention(RUNTIME)
-@Target(METHOD)
+@Target({ METHOD, TYPE })
 public @interface Priority {

 	/**
--- a/core/src/main/java/dev/kske/eventbus/core/handler/CallbackEventHandler.java
+++ b/core/src/main/java/dev/kske/eventbus/core/handler/CallbackEventHandler.java
@ -0,0 +1,73 @@
+package dev.kske.eventbus.core.handler;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.function.Consumer;
+
+/**
+ * An event handler wrapping a callback method.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.0
+ */
+public final class CallbackEventHandler implements EventHandler {
+
+	private final Class<?>			eventType;
+	private final Consumer<Object>	callback;
+	private final boolean			polymorphic;
+	private final int				priority;
+
+	/**
+	 * Constructs a callback event handler.
+	 *
+	 * @param <E>         the event type of the handler
+	 * @param eventType   the event type of the handler
+	 * @param callback    the callback method to execute when the handler is invoked
+	 * @param polymorphic whether the handler is polymorphic
+	 * @param priority    the priority of the handler
+	 * @since 1.2.0
+	 */
+	@SuppressWarnings("unchecked")
+	public <E> CallbackEventHandler(Class<E> eventType, Consumer<E> callback, boolean polymorphic,
+		int priority) {
+		this.eventType		= eventType;
+		this.callback		= (Consumer<Object>) callback;
+		this.polymorphic	= polymorphic;
+		this.priority		= priority;
+	}
+
+	@Override
+	public void execute(Object event) throws InvocationTargetException {
+		try {
+			callback.accept(event);
+		} catch (RuntimeException e) {
+			throw new InvocationTargetException(e, "Callback event handler failed!");
+		}
+	}
+
+	@Override
+	public String toString() {
+		return String.format(
+			"CallbackEventHandler[eventType=%s, polymorphic=%b, priority=%d]",
+			eventType, polymorphic, priority);
+	}
+
+	@Override
+	public Consumer<?> getListener() {
+		return callback;
+	}
+
+	@Override
+	public Class<?> getEventType() {
+		return eventType;
+	}
+
+	@Override
+	public int getPriority() {
+		return priority;
+	}
+
+	@Override
+	public boolean isPolymorphic() {
+		return polymorphic;
+	}
+}
--- a/core/src/main/java/dev/kske/eventbus/core/handler/EventHandler.java
+++ b/core/src/main/java/dev/kske/eventbus/core/handler/EventHandler.java
@ -0,0 +1,53 @@
+package dev.kske.eventbus.core.handler;
+
+import java.lang.reflect.InvocationTargetException;
+
+import dev.kske.eventbus.core.*;
+
+/**
+ * Internal representation of an event handling method.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.0
+ * @see EventBus
+ */
+public interface EventHandler {
+
+	/**
+	 * Executes the event handler.
+	 *
+	 * @param event the event used as the method parameter
+	 * @throws EventBusException         if the event handler isn't accessible or has an invalid
+	 *                                   signature
+	 * @throws InvocationTargetException if the handler throws an exception
+	 * @throws EventBusException         if the handler has the wrong signature or is inaccessible
+	 * @since 1.2.0
+	 */
+	void execute(Object event) throws EventBusException, InvocationTargetException;
+
+	/**
+	 * @return the listener containing this handler
+	 * @since 1.2.0
+	 */
+	Object getListener();
+
+	/**
+	 * @return the event type this handler listens for
+	 * @since 1.2.0
+	 */
+	Class<?> getEventType();
+
+	/**
+	 * @return the priority of this handler
+	 * @since 1.2.0
+	 * @see Priority
+	 */
+	int getPriority();
+
+	/**
+	 * @return whether this handler also accepts subtypes of the event type
+	 * @since 1.2.0
+	 * @see Polymorphic
+	 */
+	boolean isPolymorphic();
+}
--- a/core/src/main/java/dev/kske/eventbus/core/handler/ReflectiveEventHandler.java
+++ b/core/src/main/java/dev/kske/eventbus/core/handler/ReflectiveEventHandler.java
@ -0,0 +1,105 @@
+package dev.kske.eventbus.core.handler;
+
+import java.lang.reflect.*;
+
+import dev.kske.eventbus.core.*;
+
+/**
+ * An event handler wrapping a method annotated with {@link Event} and executing it using
+ * reflection.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.0
+ */
+public final class ReflectiveEventHandler implements EventHandler {
+
+	private final Object	listener;
+	private final Method	method;
+	private final Class<?>	eventType;
+	private final boolean	useParameter;
+	private final boolean	polymorphic;
+	private final int		priority;
+
+	/**
+	 * Constructs a reflective event handler.
+	 *
+	 * @param listener        the listener containing the handler
+	 * @param method          the handler method
+	 * @param annotation      the event annotation
+	 * @param defPolymorphism the predefined polymorphism (default or listener-level)
+	 * @param defPriority     the predefined priority (default or listener-level)
+	 * @throws EventBusException if the method or the annotation do not comply with the
+	 *                           specification
+	 * @since 1.2.0
+	 */
+	public ReflectiveEventHandler(Object listener, Method method, Event annotation,
+		boolean defPolymorphism, int defPriority) throws EventBusException {
+		this.listener	= listener;
+		this.method		= method;
+		useParameter	= annotation.value() == void.class;
+
+		// Check handler signature
+		if (method.getParameterCount() == 0 && useParameter)
+			throw new EventBusException(method + " does not define an event type!");
+
+		if (method.getParameterCount() == 1 && !useParameter)
+			throw new EventBusException(method + " defines an ambiguous event type!");
+
+		if (method.getParameterCount() > 1)
+			throw new EventBusException(method + " defines more than one parameter!");
+
+		// Determine handler properties
+		eventType	= useParameter ? method.getParameterTypes()[0] : annotation.value();
+		polymorphic	= method.isAnnotationPresent(Polymorphic.class)
+			? method.getAnnotation(Polymorphic.class).value()
+			: defPolymorphism;
+		priority	= method.isAnnotationPresent(Priority.class)
+			? method.getAnnotation(Priority.class).value()
+			: defPriority;
+
+		// Try to allow access if the method is not accessible
+		if (!method.canAccess(Modifier.isStatic(method.getModifiers()) ? null : listener))
+			method.setAccessible(true);
+	}
+
+	@Override
+	public void execute(Object event) throws EventBusException, InvocationTargetException {
+		try {
+			if (useParameter)
+				method.invoke(getListener(), event);
+			else
+				method.invoke(getListener());
+		} catch (IllegalArgumentException e) {
+			throw new EventBusException("Event handler rejected target / argument!", e);
+		} catch (IllegalAccessException e) {
+			throw new EventBusException("Event handler is not accessible!", e);
+		}
+	}
+
+	@Override
+	public String toString() {
+		return String.format(
+			"ReflectiveEventHandler[eventType=%s, polymorphic=%b, priority=%d, method=%s, useParameter=%b]",
+			eventType, polymorphic, priority, method, useParameter);
+	}
+
+	@Override
+	public Object getListener() {
+		return listener;
+	}
+
+	@Override
+	public Class<?> getEventType() {
+		return eventType;
+	}
+
+	@Override
+	public int getPriority() {
+		return priority;
+	}
+
+	@Override
+	public boolean isPolymorphic() {
+		return polymorphic;
+	}
+}
--- a/core/src/main/java/dev/kske/eventbus/core/handler/package-info.java
+++ b/core/src/main/java/dev/kske/eventbus/core/handler/package-info.java
@ -0,0 +1,8 @@
+/**
+ * Contains the internal representation of event handling methods.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.0
+ * @see dev.kske.eventbus.core.handler.EventHandler
+ */
+package dev.kske.eventbus.core.handler;
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/package-info.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/package-info.java
--- a/event-bus-core/src/main/java/module-info.java
+++ b/event-bus-core/src/main/java/module-info.java
--- a/event-bus-core/src/test/java/dev/kske/eventbus/core/CancelTest.java
+++ b/event-bus-core/src/test/java/dev/kske/eventbus/core/CancelTest.java
--- a/core/src/test/java/dev/kske/eventbus/core/DeadTest.java
+++ b/core/src/test/java/dev/kske/eventbus/core/DeadTest.java
@ -0,0 +1,49 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests the dispatching of a dead event if an event could not be delivered.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.1.0
+ */
+class DeadTest {
+
+	EventBus	bus		= new EventBus();
+	String		event	= "This event has no handler";
+	boolean		deadEventHandled;
+
+	/**
+	 * Tests dead event delivery.
+	 *
+	 * @since 1.1.0
+	 */
+	@Test
+	void testDeadEvent() {
+		bus.registerListener(this);
+		bus.dispatch(event);
+		assertTrue(deadEventHandled);
+		bus.removeListener(this);
+	}
+
+	/**
+	 * Tests how the event bus reacts to an unhandled dead event. This should not lead to an
+	 * exception or an endless recursion and should be logged instead.
+	 *
+	 * @since 1.1.0
+	 */
+	@Test
+	void testUnhandledDeadEvent() {
+		bus.dispatch(event);
+	}
+
+	@Event
+	void onDeadEvent(DeadEvent deadEvent) {
+		assertEquals(bus, deadEvent.getEventBus());
+		assertEquals(event, deadEvent.getEvent());
+		deadEventHandled = true;
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/DispatchTest.java
+++ b/core/src/test/java/dev/kske/eventbus/core/DispatchTest.java
@ -0,0 +1,88 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.*;
+
+/**
+ * Tests the dispatching mechanism of the event bus.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ */
+@Polymorphic
+@Priority(150)
+class DispatchTest {
+
+	EventBus bus;
+
+	/**
+	 * Constructs an event bus and registers this test instance as an event listener.
+	 *
+	 * @since 0.0.1
+	 */
+	@BeforeEach
+	void registerListener() {
+		bus = new EventBus();
+		bus.registerListener(this);
+		bus.registerListener(SimpleEvent.class, e -> {
+			e.increment();
+			assertEquals(3, e.getCounter());
+		});
+	}
+
+	/**
+	 * Tests {@link EventBus#dispatch(Object)} with multiple handler priorities, a polymorphic
+	 * handler and a static handler.
+	 *
+	 * @since 0.0.1
+	 */
+	@Test
+	void testDispatch() {
+		bus.dispatch(new SimpleEventSub());
+		bus.dispatch(new SimpleEvent());
+	}
+
+	/**
+	 * Tests {@link EventBus#debugExecutionOrder(Class)} based on the currently registered handlers.
+	 *
+	 * @since 1.2.0
+	 */
+	@Test
+	void testDebugExecutionOrder() {
+		assertEquals(
+			"Event handler execution order for class dev.kske.eventbus.core.SimpleEvent (3 handler(s)):\n"
+				+ "==========================================================================================\n"
+				+ "ReflectiveEventHandler[eventType=class dev.kske.eventbus.core.SimpleEvent, polymorphic=true, priority=200, method=void dev.kske.eventbus.core.DispatchTest.onSimpleEventFirst(dev.kske.eventbus.core.SimpleEvent), useParameter=true]\n"
+				+ "ReflectiveEventHandler[eventType=class dev.kske.eventbus.core.SimpleEvent, polymorphic=false, priority=150, method=static void dev.kske.eventbus.core.DispatchTest.onSimpleEventSecond(dev.kske.eventbus.core.SimpleEvent), useParameter=true]\n"
+				+ "CallbackEventHandler[eventType=class dev.kske.eventbus.core.SimpleEvent, polymorphic=false, priority=100]\n"
+				+ "==========================================================================================",
+			bus.debugExecutionOrder(SimpleEvent.class));
+	}
+
+	/**
+	 * Tests whether the handlers bound to an event type are correct when retrieved from the binding
+	 * cache. On the second call of {@link EventBus#debugExecutionOrder(Class)} the cache is used.
+	 *
+	 * @since 1.3.0
+	 */
+	@Test
+	void testBindingCache() {
+		assertEquals(bus.debugExecutionOrder(SimpleEventSub.class),
+			bus.debugExecutionOrder(SimpleEventSub.class));
+	}
+
+	@Event
+	@Priority(200)
+	void onSimpleEventFirst(SimpleEvent event) {
+		event.increment();
+		assertTrue(event.getCounter() == 1 || event.getCounter() == 2);
+	}
+
+	@Event
+	@Polymorphic(false)
+	static void onSimpleEventSecond(SimpleEvent event) {
+		event.increment();
+		assertEquals(2, event.getCounter());
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/ExceptionTest.java
+++ b/core/src/test/java/dev/kske/eventbus/core/ExceptionTest.java
@ -0,0 +1,62 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests the dispatching of an exception event if an event handler threw an exception.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.1.0
+ */
+class ExceptionTest {
+
+	EventBus			bus			= new EventBus();
+	String				event		= "This event will cause an exception";
+	RuntimeException	exception	= new RuntimeException("I failed");
+	boolean				exceptionEventHandled;
+
+	/**
+	 * Tests exception event delivery.
+	 *
+	 * @since 1.1.0
+	 */
+	@Test
+	void testExceptionEvent() {
+		bus.registerListener(this);
+		bus.registerListener(new ExceptionListener());
+		bus.dispatch(event);
+		assertTrue(exceptionEventHandled);
+		bus.clearListeners();
+	}
+
+	/**
+	 * Tests how the event bus reacts to an unhandled exception event. This should not lead to an
+	 * exception or an endless recursion and should be logged instead.
+	 *
+	 * @since 1.1.0
+	 */
+	@Test
+	void testUnhandledExceptionEvent() {
+		bus.registerListener(this);
+		bus.dispatch(event);
+		bus.removeListener(this);
+	}
+
+	@Event(String.class)
+	void onString() {
+		throw exception;
+	}
+
+	class ExceptionListener {
+
+		@Event
+		void onExceptionEvent(ExceptionEvent exceptionEvent) {
+			assertEquals(bus, exceptionEvent.getEventBus());
+			assertEquals(event, exceptionEvent.getEvent());
+			assertEquals(exception, exceptionEvent.getCause());
+			exceptionEventHandled = true;
+		}
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/ExceptionWrapperTest.java
+++ b/core/src/test/java/dev/kske/eventbus/core/ExceptionWrapperTest.java
@ -0,0 +1,33 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests the behavior of the event bus when an {@link ExceptionWrapper} is thrown.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.1
+ */
+class ExceptionWrapperTest {
+
+	EventBus	bus		= new EventBus();
+	String		event	= "This event will cause an exception";
+
+	/**
+	 * Tests transparent rethrowing of an exception wrapper by {@link EventBus#dispatch(Object)}.
+	 *
+	 * @since 1.2.1
+	 */
+	@Test
+	void testExceptionWrapper() {
+		bus.registerListener(this);
+		assertThrows(ExceptionWrapper.class, () -> bus.dispatch(event));
+	}
+
+	@Event(String.class)
+	void onString() {
+		throw new ExceptionWrapper(new RuntimeException("I failed!"));
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/InheritanceTest.java
+++ b/core/src/test/java/dev/kske/eventbus/core/InheritanceTest.java
@ -0,0 +1,43 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests whether event handlers correctly work in the context of an inheritance hierarchy. The
+ * effect of handler priorities is also accounted for.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.3.0
+ */
+class InheritanceTest extends SimpleEventListenerBase implements SimpleEventListenerInterface {
+
+	EventBus bus = new EventBus();
+
+	@Test
+	void test() {
+		bus.registerListener(this);
+		var event = new SimpleEvent();
+
+		bus.dispatch(event);
+		assertSame(3, event.getCounter());
+	}
+
+	@Override
+	void onSimpleEventAbstractHandler(SimpleEvent event) {
+		assertSame(1, event.getCounter());
+	}
+
+	@Override
+	public void onSimpleEventInterfaceHandler(SimpleEvent event) {
+		event.increment();
+	}
+
+	@Event
+	@Priority(250)
+	private void onSimpleEventPrivate(SimpleEvent event) {
+		assertSame(0, event.getCounter());
+		event.increment();
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/NestedTest.java
+++ b/core/src/test/java/dev/kske/eventbus/core/NestedTest.java
@ -0,0 +1,73 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.*;
+
+/**
+ * Tests nested event dispatches.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.2.0
+ */
+class NestedTest {
+
+	EventBus	bus;
+	boolean		nestedHit;
+
+	/**
+	 * Constructs an event bus and registers this test instance as an event listener.
+	 *
+	 * @since 1.2.0
+	 */
+	@BeforeEach
+	void registerListener() {
+		bus = new EventBus();
+		bus.registerListener(this);
+	}
+
+	/**
+	 * Dispatches a simple event, which should in turn cause a string to be dispatched as a nested
+	 * event. If the corresponding handler sets {@link #nestedHit} to {@code true}, the test is
+	 * successful.
+	 *
+	 * @since 1.2.0
+	 */
+	@Test
+	void testNestedDispatch() {
+		bus.dispatch(new SimpleEvent());
+		assertTrue(nestedHit);
+	}
+
+	/**
+	 * Dispatches a string as a nested event and cancels the current dispatch afterwards.
+	 *
+	 * @since 1.2.0
+	 */
+	@Event(SimpleEvent.class)
+	void onSimpleEvent() {
+		bus.dispatch("Nested event");
+		bus.cancel();
+	}
+
+	/**
+	 * Sets {@link #nestedHit} to {@code true} indicating that nested dispatches work.
+	 *
+	 * @since 1.2.0
+	 */
+	@Event(String.class)
+	void onString() {
+		nestedHit = true;
+	}
+
+	/**
+	 * Fails the test if an exception is caused during the dispatch.
+	 *
+	 * @param e the event containing the exception
+	 * @since 1.2.0
+	 */
+	@Event
+	void onException(ExceptionEvent e) {
+		fail("Exception during dispatch", e.getCause());
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/SimpleEvent.java
+++ b/core/src/test/java/dev/kske/eventbus/core/SimpleEvent.java
@ -0,0 +1,31 @@
+package dev.kske.eventbus.core;
+
+/**
+ * A simple event for testing purposes. The event contains a counter that is supposed to be
+ * incremented when the event is processed by a handler. That way it is possible to test whether all
+ * handlers that were supposed to be invoked were in fact invoked.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ */
+class SimpleEvent {
+
+	private int counter;
+
+	@Override
+	public String toString() {
+		return String.format("%s[%d]", getClass().getSimpleName(), counter);
+	}
+
+	void increment() {
+		++counter;
+	}
+
+	int getCounter() {
+		return counter;
+	}
+
+	void reset() {
+		counter = 0;
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/SimpleEventListenerBase.java
+++ b/core/src/test/java/dev/kske/eventbus/core/SimpleEventListenerBase.java
@ -0,0 +1,25 @@
+package dev.kske.eventbus.core;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * An abstract class defining a package-private and a private handler for {@link SimpleEvent}.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.3.0
+ */
+@Priority(200)
+abstract class SimpleEventListenerBase {
+
+	@Event
+	void onSimpleEventAbstractHandler(SimpleEvent event) {
+		fail("This handler should not be invoked");
+	}
+
+	@Event
+	@Priority(150)
+	private void onSimpleEventPrivate(SimpleEvent event) {
+		assertSame(1, event.getCounter());
+		event.increment();
+	}
+}
--- a/core/src/test/java/dev/kske/eventbus/core/SimpleEventListenerInterface.java
+++ b/core/src/test/java/dev/kske/eventbus/core/SimpleEventListenerInterface.java
@ -0,0 +1,14 @@
+package dev.kske.eventbus.core;
+
+/**
+ * An interface defining a single handler for {@link SimpleEvent}.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 1.3.0
+ */
+interface SimpleEventListenerInterface {
+
+	@Priority(120)
+	@Event
+	void onSimpleEventInterfaceHandler(SimpleEvent event);
+}
--- a/event-bus-core/src/test/java/dev/kske/eventbus/core/SimpleEventSub.java
+++ b/event-bus-core/src/test/java/dev/kske/eventbus/core/SimpleEventSub.java
@ -6,4 +6,4 @@ package dev.kske.eventbus.core;
 * @author Kai S. K. Engelbart
 * @since 0.0.4
 */
-public class SimpleEventSub extends SimpleEvent {}
+class SimpleEventSub extends SimpleEvent {}
--- a/event-bus-core/pom.xml
+++ b/event-bus-core/pom.xml
@ -1,30 +0,0 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
-	<modelVersion>4.0.0</modelVersion>
-
-	<artifactId>event-bus-core</artifactId>
-	<name>Event Bus Core</name>
-
-	<parent>
-		<groupId>dev.kske</groupId>
-		<artifactId>event-bus</artifactId>
-		<version>1.0.0</version>
-	</parent>
-
-	<dependencies>
-		<dependency>
-			<groupId>org.junit.jupiter</groupId>
-			<artifactId>junit-jupiter-api</artifactId>
-			<version>5.6.2</version>
-			<scope>test</scope>
-		</dependency>
-	</dependencies>
-
-	<build>
-
-		<!-- Disable resource folder -->
-		<resources />
-
-	</build>
-</project>
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/EventBus.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/EventBus.java
@ -1,210 +0,0 @@
-package dev.kske.eventbus.core;
-
-import java.lang.System.Logger;
-import java.lang.System.Logger.Level;
-import java.util.*;
-import java.util.concurrent.ConcurrentHashMap;
-
-/**
- * Event listeners can be registered at an event bus to be notified when an event is dispatched.
- * <p>
- * A singleton instance of this class can be lazily created and acquired using the
- * {@link EventBus#getInstance()} method.
- * <p>
- * This is a thread-safe implementation.
- *
- * @author Kai S. K. Engelbart
- * @since 0.0.1
- * @see Event
- */
-public final class EventBus {
-
-	/**
-	 * Holds the state of the dispatching process on one thread.
-	 *
-	 * @since 0.1.0
-	 */
-	private static final class DispatchState {
-
-		boolean isDispatching, isCancelled;
-	}
-
-	private static volatile EventBus singletonInstance;
-
-	private static final Logger logger = System.getLogger(EventBus.class.getName());
-
-	/**
-	 * Produces a singleton instance of the event bus. It is lazily initialized on the first call.
-	 *
-	 * @return a singleton instance of the event bus.
-	 * @since 0.0.2
-	 */
-	public static EventBus getInstance() {
-		EventBus instance = singletonInstance;
-		if (instance == null)
-			synchronized (EventBus.class) {
-				if ((instance = singletonInstance) == null) {
-					logger.log(Level.DEBUG, "Initializing singleton event bus instance");
-					instance = singletonInstance = new EventBus();
-				}
-			}
-		return instance;
-	}
-
-	private final Map<Class<?>, TreeSet<EventHandler>>	bindings			=
-		new ConcurrentHashMap<>();
-	private final Set<Object>							registeredListeners	=
-		ConcurrentHashMap.newKeySet();
-	private final ThreadLocal<DispatchState>			dispatchState		=
-		ThreadLocal.withInitial(DispatchState::new);
-
-	/**
-	 * Dispatches an event to all event handlers registered for it in descending order of their
-	 * priority.
-	 *
-	 * @param event the event to dispatch
-	 * @since 0.0.1
-	 */
-	public void dispatch(Object event) {
-		Objects.requireNonNull(event);
-		logger.log(Level.INFO, "Dispatching event {0}", event);
-
-		// Set dispatch state
-		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);
-			}
-
-		// Reset dispatch state
-		state.isDispatching = false;
-
-		logger.log(Level.DEBUG, "Finished dispatching event {0}", event);
-	}
-
-	/**
-	 * Searches for the event handlers bound to an event class.
-	 *
-	 * @param eventClass the event class to use for the search
-	 * @return all event handlers registered for the event class
-	 * @since 0.0.1
-	 */
-	private List<EventHandler> getHandlersFor(Class<?> eventClass) {
-
-		// Get handlers defined for the event class
-		Set<EventHandler> handlers = bindings.getOrDefault(eventClass, new TreeSet<>());
-
-		// Get subtype 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);
-	}
-
-	/**
-	 * Cancels an event that is currently dispatched from inside an event handler.
-	 *
-	 * @throws EventBusException if the calling thread is not an active dispatching thread
-	 * @since 0.1.0
-	 */
-	public void cancel() {
-		var state = dispatchState.get();
-		if (state.isDispatching && !state.isCancelled)
-			state.isCancelled = true;
-		else
-			throw new EventBusException("Calling thread not an active dispatching thread!");
-	}
-
-	/**
-	 * Registers an event listener at this event bus.
-	 *
-	 * @param listener the listener to register
-	 * @throws EventBusException if the listener is already registered or a declared event handler
-	 *                           does not comply with the specification
-	 * @since 0.0.1
-	 * @see Event
-	 */
-	public void registerListener(Object listener) throws EventBusException {
-		Objects.requireNonNull(listener);
-		if (registeredListeners.contains(listener))
-			throw new EventBusException(listener + " already registered!");
-		logger.log(Level.INFO, "Registering event listener {0}", listener.getClass().getName());
-		boolean handlerBound = false;
-
-		registeredListeners.add(listener);
-		for (var method : listener.getClass().getDeclaredMethods()) {
-			Event annotation = method.getAnnotation(Event.class);
-
-			// Skip methods without annotations
-			if (annotation == null)
-				continue;
-
-			// Initialize and bind the handler
-			var handler = new EventHandler(listener, method, annotation);
-			bindings.putIfAbsent(handler.getEventType(), new TreeSet<>());
-			logger.log(Level.DEBUG, "Binding event handler {0}", handler);
-			bindings.get(handler.getEventType())
-				.add(handler);
-			handlerBound = true;
-		}
-
-		if (!handlerBound)
-			logger.log(
-				Level.WARNING,
-				"No event handlers bound for event listener {0}",
-				listener.getClass().getName());
-	}
-
-	/**
-	 * Removes a specific listener from this event bus.
-	 *
-	 * @param listener the listener to remove
-	 * @since 0.0.1
-	 */
-	public void removeListener(Object listener) {
-		Objects.requireNonNull(listener);
-		logger.log(Level.INFO, "Removing event listener {0}", listener.getClass().getName());
-
-		for (var binding : bindings.values()) {
-			var it = binding.iterator();
-			while (it.hasNext()) {
-				var handler = it.next();
-				if (handler.getListener() == listener) {
-					logger.log(Level.DEBUG, "Unbinding event handler {0}", handler);
-					it.remove();
-				}
-			}
-		}
-		registeredListeners.remove(listener);
-	}
-
-	/**
-	 * Removes all event listeners from this event bus.
-	 *
-	 * @since 0.0.1
-	 */
-	public void clearListeners() {
-		logger.log(Level.INFO, "Clearing event listeners");
-		bindings.clear();
-		registeredListeners.clear();
-	}
-
-	/**
-	 * Provides an unmodifiable view of the event listeners registered at this event bus.
-	 *
-	 * @return all registered event listeners
-	 * @since 0.0.1
-	 */
-	public Set<Object> getRegisteredListeners() {
-		return Collections.unmodifiableSet(registeredListeners);
-	}
-}
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/EventBusException.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/EventBusException.java
@ -1,33 +0,0 @@
-package dev.kske.eventbus.core;
-
-/**
- * This runtime exception is thrown when an event bus error occurs. This can
- * either occur while registering event listeners with invalid handlers, or when
- * an event handler throws an exception.
- *
- * @author Kai S. K. Engelbart
- * @since 0.0.1
- */
-public class EventBusException extends RuntimeException {
-
-	private static final long serialVersionUID = 1L;
-
-	/**
-	 * Creates a new event bus exception.
-	 *
-	 * @param message the message to display
-	 * @param cause   the cause of this exception
-	 */
-	public EventBusException(String message, Throwable cause) {
-		super(message, cause);
-	}
-
-	/**
-	 * Creates a new event bus exception.
-	 *
-	 * @param message the message to display
-	 */
-	public EventBusException(String message) {
-		super(message);
-	}
-}
--- a/event-bus-core/src/main/java/dev/kske/eventbus/core/EventHandler.java
+++ b/event-bus-core/src/main/java/dev/kske/eventbus/core/EventHandler.java
@ -1,133 +0,0 @@
-package dev.kske.eventbus.core;
-
-import java.lang.reflect.*;
-
-import dev.kske.eventbus.core.Event.USE_PARAMETER;
-
-/**
- * Internal representation of an event handling method.
- *
- * @author Kai S. K. Engelbart
- * @since 0.0.1
- * @see EventBus
- */
-final class EventHandler implements Comparable<EventHandler> {
-
-	/**
-	 * The priority assigned to every event handler without an explicitly defined priority.
-	 *
-	 * @since 1.0.0
-	 * @see Priority
-	 */
-	public static final int DEFAULT_PRIORITY = 100;
-
-	private final Object	listener;
-	private final Method	method;
-	private final Class<?>	eventType;
-	private final boolean	useParameter;
-	private final boolean	polymorphic;
-	private final int		priority;
-
-	/**
-	 * Constructs an event handler.
-	 *
-	 * @param listener   the listener containing the handler
-	 * @param method     the handler method
-	 * @param annotation the event annotation
-	 * @throws EventBusException if the method or the annotation do not comply with the
-	 *                           specification
-	 * @since 0.0.1
-	 */
-	EventHandler(Object listener, Method method, Event annotation) throws EventBusException {
-		this.listener	= listener;
-		this.method		= method;
-		useParameter	= annotation.value() == USE_PARAMETER.class;
-
-		// Check handler signature
-		if (method.getParameterCount() == 0 && useParameter)
-			throw new EventBusException(method + " does not define an event type!");
-
-		if (method.getParameterCount() == 1 && !useParameter)
-			throw new EventBusException(method + " defines an ambiguous event type!");
-
-		if (method.getParameterCount() > 1)
-			throw new EventBusException(method + " defines more than one parameter!");
-
-		// Determine handler properties
-		eventType	= useParameter ? method.getParameterTypes()[0] : annotation.value();
-		polymorphic	= method.isAnnotationPresent(Polymorphic.class);
-		priority	= method.isAnnotationPresent(Priority.class)
-			? method.getAnnotation(Priority.class).value()
-			: DEFAULT_PRIORITY;
-
-		// Allow access if the method is non-public
-		method.setAccessible(true);
-	}
-
-	/**
-	 * Compares this to another event handler based on priority. In case of equal priority a
-	 * non-zero value based on hash codes is returned.
-	 * <p>
-	 * This is used to retrieve event handlers in order of descending priority from a tree set.
-	 *
-	 * @since 0.0.1
-	 */
-	@Override
-	public int compareTo(EventHandler other) {
-		int priority = other.priority - this.priority;
-		if (priority == 0)
-			priority = listener.hashCode() - other.listener.hashCode();
-		return priority == 0 ? hashCode() - other.hashCode() : priority;
-	}
-
-	@Override
-	public String toString() {
-		return String.format(
-			"EventHandler[method=%s, eventType=%s, useParameter=%b, polymorphic=%b, priority=%d]",
-			method, eventType, useParameter, polymorphic, priority);
-	}
-
-	/**
-	 * Executes the event handler.
-	 *
-	 * @param event the event used as the method parameter
-	 * @throws EventBusException if the handler throws an exception
-	 * @since 0.0.1
-	 */
-	void execute(Object event) throws EventBusException {
-		try {
-			if (useParameter)
-				method.invoke(listener, event);
-			else
-				method.invoke(listener);
-		} catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
-			throw new EventBusException("Failed to invoke event handler!", e);
-		}
-	}
-
-	/**
-	 * @return the listener containing this handler
-	 * @since 0.0.1
-	 */
-	Object getListener() { return listener; }
-
-	/**
-	 * @return the event type this handler listens for
-	 * @since 0.0.3
-	 */
-	Class<?> getEventType() { return eventType; }
-
-	/**
-	 * @return the priority of this handler
-	 * @since 0.0.1
-	 * @see Priority
-	 */
-	int getPriority() { return priority; }
-
-	/**
-	 * @return whether this handler is polymorphic
-	 * @since 1.0.0
-	 * @see Polymorphic
-	 */
-	boolean isPolymorphic() { return polymorphic; }
-}
--- a/event-bus-core/src/test/java/dev/kske/eventbus/core/DispatchTest.java
+++ b/event-bus-core/src/test/java/dev/kske/eventbus/core/DispatchTest.java
@ -1,61 +0,0 @@
-package dev.kske.eventbus.core;
-
-import static org.junit.jupiter.api.Assertions.*;
-
-import org.junit.jupiter.api.*;
-
-/**
- * Tests the dispatching mechanism of the event bus.
- *
- * @author Kai S. K. Engelbart
- * @since 0.0.1
- */
-class DispatchTest {
-
-	EventBus	bus;
-	static int	hits;
-
-	/**
-	 * Constructs an event bus and registers this test instance as an event listener.
-	 *
-	 * @since 0.0.1
-	 */
-	@BeforeEach
-	void registerListener() {
-		bus = new EventBus();
-		bus.registerListener(this);
-	}
-
-	/**
-	 * Tests {@link EventBus#dispatch(Object)} with multiple handler priorities, a subtype handler
-	 * and a static handler.
-	 *
-	 * @since 0.0.1
-	 */
-	@Test
-	void testDispatch() {
-		bus.dispatch(new SimpleEventSub());
-		bus.dispatch(new SimpleEvent());
-	}
-
-	@Event(SimpleEvent.class)
-	@Priority(200)
-	@Polymorphic
-	void onSimpleEventFirst() {
-		++hits;
-		assertTrue(hits == 1 || hits == 2);
-	}
-
-	@Event(SimpleEvent.class)
-	@Priority(150)
-	static void onSimpleEventSecond() {
-		++hits;
-		assertEquals(3, hits);
-	}
-
-	@Event
-	void onSimpleEventThird(SimpleEvent event) {
-		++hits;
-		assertEquals(4, hits);
-	}
-}
--- a/event-bus-core/src/test/java/dev/kske/eventbus/core/SimpleEvent.java
+++ b/event-bus-core/src/test/java/dev/kske/eventbus/core/SimpleEvent.java
@ -1,9 +0,0 @@
-package dev.kske.eventbus.core;
-
-/**
- * A simple event for testing purposes.
- *
- * @author Kai S. K. Engelbart
- * @since 0.0.1
- */
-public class SimpleEvent {}
--- a/pom.xml
+++ b/pom.xml
@ -5,22 +5,24 @@

 	<groupId>dev.kske</groupId>
 	<artifactId>event-bus</artifactId>
-	<version>1.0.0</version>
+	<version>1.2.0</version>
 	<packaging>pom</packaging>

 	<name>Event Bus</name>
-	<description>An event handling framework for Java utilizing annotations.</description>
+	<description>An event handling library for Java utilizing annotations.</description>
 	<url>https://git.kske.dev/kske/event-bus</url>

 	<modules>
-		<module>event-bus-core</module>
-		<module>event-bus-proc</module>
+		<module>core</module>
+		<module>proc</module>
 	</modules>

 	<licenses>
 		<license>
-			<name>GNU General Public License Version 3</name>
-			<url>http://www.gnu.org/licenses/gpl.txt</url>
+			<name>Apache License, Version 2.0</name>
+			<url>https://www.apache.org/licenses/LICENSE-2.0.txt</url>
+			<distribution>repo</distribution>
+			<comments>A business-friendly OSS license</comments>
 		</license>
 	</licenses>

@ -38,6 +40,19 @@
 		</developer>
 	</developers>

+	<contributors>
+		<contributor>
+			<name>Leon Hofmeister</name>
+			<email>leon@kske.dev</email>
+			<url>https://git.kske.dev/delvh</url>
+			<roles>
+				<role>qa</role>
+				<role>tester</role>
+			</roles>
+			<timezone>Europe/Berlin</timezone>
+		</contributor>
+	</contributors>
+
 	<scm>
 		<connection>scm:git:https://git.kske.dev/kske/event-bus.git</connection>
 		<developerConnection>scm:git:ssh://git@git.kske.dev:420/kske/event-bus.git</developerConnection>
@ -105,6 +120,28 @@
 						</goals>
 					</execution>
 				</executions>
+
+				<!-- Support JDK-style Javadoc tags -->
+				<configuration>
+					<tags>
+						<tag>
+							<name>apiNote</name>
+							<placement>a</placement>
+							<head>API Note:</head>
+						</tag>
+						<tag>
+							<name>implSpec</name>
+							<placement>a</placement>
+							<head>Implementation Requirements:</head>
+						</tag>
+						<tag>
+							<name>implNote</name>
+							<placement>a</placement>
+							<head>Implementation Note:</head>
+						</tag>
+					</tags>
+				</configuration>
+
 			</plugin>

 			<!-- GPG sign JAR -->
--- a/event-bus-proc/.classpath
+++ b/event-bus-proc/.classpath
@ -16,17 +16,17 @@
 			<attribute name="maven.pomderived" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry kind="src" output="target/test-classes" path="home/kske/git/event-bus/event-bus-ap">
+	<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
 		<attributes>
 			<attribute name="optional" value="true"/>
 			<attribute name="maven.pomderived" value="true"/>
 			<attribute name="test" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
-		<attributes>
-			<attribute name="maven.pomderived" value="true"/>
-		</attributes>
-	</classpathentry>
 	<classpathentry kind="output" path="target/classes"/>
 </classpath>
--- a/event-bus-proc/.project
+++ b/event-bus-proc/.project
--- a/event-bus-proc/pom.xml
+++ b/event-bus-proc/pom.xml
@ -11,7 +11,7 @@
 	<parent>
 		<groupId>dev.kske</groupId>
 		<artifactId>event-bus</artifactId>
-		<version>1.0.0</version>
+		<version>1.2.0</version>
 	</parent>

 	<dependencies>
@ -24,9 +24,6 @@

 	<build>

-		<!-- Disable test folder -->
-		<testSourceDirectory />
-
 		<plugins>

 			<!-- Prevent annotation processing error during compilation -->
--- a/event-bus-proc/src/main/java/dev/kske/eventbus/proc/EventProcessor.java
+++ b/event-bus-proc/src/main/java/dev/kske/eventbus/proc/EventProcessor.java
@ -47,13 +47,12 @@ public class EventProcessor extends AbstractProcessor {

 				// Task failed successfully
 				eventType		= e.getTypeMirror();
-				useParameter	= processingEnv.getTypeUtils().isSameType(eventType,
-					getTypeMirror(Event.USE_PARAMETER.class));
+				useParameter	= eventType.getKind() == TypeKind.VOID;
 			}

 			// Check handler signature
 			boolean pass = false;
-			if (useParameter && eventHandler.getParameters().size() == 0)
+			if (useParameter && eventHandler.getParameters().isEmpty())
 				error(eventHandler, "The method or the annotation must define the event type");
 			else if (!useParameter && eventHandler.getParameters().size() == 1)
 				error(eventHandler,
@ -63,6 +62,10 @@ public class EventProcessor extends AbstractProcessor {
 			else
 				pass = true;

+			// Warn the user about unused return values
+			if (useParameter && eventHandler.getReturnType().getKind() != TypeKind.VOID)
+				warning(eventHandler, "Unused return value");
+
 			// Abort checking if the handler signature is incorrect
 			if (!pass)
 				continue;
@ -80,25 +83,60 @@ public class EventProcessor extends AbstractProcessor {
 				}
 			}

-			// Check for handlers for abstract types that aren't polymorphic
+			// Get the listener containing this handler
+			TypeElement listener = (TypeElement) eventHandler.getEnclosingElement();
+
+			// Default properties
+			boolean	defPolymorphic	= false;
+			int		defPriority		= 100;
+
+			// Listener-level polymorphism
+			Polymorphic	listenerPolymorphic		= listener.getAnnotation(Polymorphic.class);
+			boolean		hasListenerPolymorphic	= listenerPolymorphic != null;
+
+			// Listener-level priority
+			Priority	listenerPriority	= listener.getAnnotation(Priority.class);
+			boolean		hasListenerPriority	= listenerPriority != null;
+
+			// Effective polymorphism
+			boolean	polymorphic				=
+				hasListenerPolymorphic ? listenerPolymorphic.value() : defPolymorphic;
+			boolean	hasHandlerPolymorphic	= eventHandler.getAnnotation(Polymorphic.class) != null;
+			if (hasHandlerPolymorphic)
+				polymorphic = eventHandler.getAnnotation(Polymorphic.class).value();
+
+			// Effective priority
+			int		priority			=
+				hasListenerPriority ? listenerPriority.value() : defPriority;
+			boolean	hasHandlerPriority	= eventHandler.getAnnotation(Priority.class) != null;
+			if (hasHandlerPriority)
+				priority = eventHandler.getAnnotation(Priority.class).value();
+
+			// Detect useless polymorphism redefinition
+			if (hasListenerPolymorphic && hasHandlerPolymorphic
+				&& listenerPolymorphic.value() == polymorphic)
+				warning(eventHandler, "@Polymorphism is already defined at listener level");
+
+			// Detect useless priority redefinition
+			if (hasListenerPriority && hasHandlerPriority && listenerPriority.value() == priority)
+				warning(eventHandler, "@Priority is already defined at the listener level");
+
+			// Detect missing or useless @Polymorphic
 			Element eventElement = ((DeclaredType) eventType).asElement();
-			if (eventHandler.getAnnotation(Polymorphic.class) == null
-				&& (eventElement.getKind() == ElementKind.INTERFACE
-					|| eventElement.getModifiers().contains(Modifier.ABSTRACT))) {
+
+			// Check for handlers for abstract types that aren't polymorphic
+			if (!polymorphic && (eventElement.getKind() == ElementKind.INTERFACE
+				|| eventElement.getModifiers().contains(Modifier.ABSTRACT)))
 				warning(eventHandler,
 					"Parameter should be instantiable or handler should use @Polymorphic");
-			}
+
+			// Check for handlers for final types that are polymorphic
+			else if (polymorphic && eventElement.getModifiers().contains(Modifier.FINAL))
+				warning(eventHandler,
+					"@Polymorphic should be removed as parameter cannot be subclassed");
 		}
 	}

-	private TypeMirror getTypeMirror(Class<?> clazz) {
-		return getTypeElement(clazz).asType();
-	}
-
-	private TypeElement getTypeElement(Class<?> clazz) {
-		return processingEnv.getElementUtils().getTypeElement(clazz.getCanonicalName());
-	}
-
 	private void warning(Element e, String msg, Object... args) {
 		processingEnv.getMessager().printMessage(Kind.WARNING, String.format(msg, args), e);
 	}
--- a/event-bus-proc/src/main/java/dev/kske/eventbus/proc/package-info.java
+++ b/event-bus-proc/src/main/java/dev/kske/eventbus/proc/package-info.java
--- a/event-bus-proc/src/main/java/module-info.java
+++ b/event-bus-proc/src/main/java/module-info.java
@ -5,7 +5,7 @@
 * @author Kai S. K. Engelbart
 * @since 1.0.0
 */
-module dev.kske.eventbus.ap {
+module dev.kske.eventbus.proc {

 	requires java.compiler;
 	requires dev.kske.eventbus.core;
--- a/event-bus-proc/src/main/resources/META-INF/services/javax.annotation.processing.Processor
+++ b/event-bus-proc/src/main/resources/META-INF/services/javax.annotation.processing.Processor
Author	SHA1	Message	Date
Kai S. K. Engelbart	cc5c07079a	Merge pull request 'Handler Caching' (#37 ) from f/handler-caching into develop zdm/event-bus/pipeline/head This commit looks good Details Reviewed-on: https://git.kske.dev/zdm/event-bus/pulls/37 Reviewed-by: delvh <leon@kske.dev>	2022-01-18 17:11:38 +01:00
Kai S. K. Engelbart	8fae4f6d76	Remove print statements from test zdm/event-bus/pipeline/head This commit looks good Details	2022-01-18 17:09:21 +01:00
Kai S. K. Engelbart	2d276a1d74	Compare listener using equals() during removal	2022-01-18 17:09:05 +01:00
Kai S. K. Engelbart	8609c6a90c	Simplify binding cache usage zdm/event-bus/pipeline/head This commit looks good Details	2022-01-18 15:00:18 +01:00
Kai S. K. Engelbart	ee9d08b2b8	Test binding cache zdm/event-bus/pipeline/head This commit looks good Details	2022-01-18 13:44:33 +01:00
Kai S. K. Engelbart	5468bddb35	Add handler cache zdm/event-bus/pipeline/head This commit looks good Details The cache has the same structure as the bindings and is updated accordingly. To ensure the correctness and efficiency of the cache, more testing has to be conducted.	2022-01-14 15:44:21 +01:00
Kai S. K. Engelbart	a8d858e8c7	Merge pull request 'Remove USE_PARAMETER' (#35 ) from f/remove-use-parameter into develop zdm/event-bus/pipeline/head This commit looks good Details Reviewed-on: https://git.kske.dev/zdm/event-bus/pulls/35 Reviewed-by: delvh <leon@kske.dev>	2022-01-13 14:40:13 +01:00
Kai S. K. Engelbart	6ee4e11161	Fix inconsistent test zdm/event-bus/pipeline/head This commit looks good Details	2022-01-12 20:17:24 +01:00
Kai S. K. Engelbart	8615a0e021	Fix Event Bus Proc module name zdm/event-bus/pipeline/head There was a failure building this commit Details	2022-01-12 20:10:44 +01:00
Kai S. K. Engelbart	3aef7d5bcb	Only update handler accessibility if necessary zdm/event-bus/pipeline/head This commit looks good Details	2022-01-12 20:04:02 +01:00
Kai S. K. Engelbart	36ed55fd71	Use void.class to determine how the event handler type is defined zdm/event-bus/pipeline/head There was a failure building this commit Details The dummy class USE_PARAMETER was necessary when the IEvent interface still existed, as void.class could not be used as a Class<? extends IEvent>. As no explicit reference to USE_PARAMETER should be present anywhere, a proper deprecation would've made little sense.	2022-01-12 19:41:53 +01:00
Kai S. K. Engelbart	999a172e72	Merge pull request 'Inherit Event Handlers' (#34 ) from f/handler-inheritance into develop zdm/event-bus/pipeline/head This commit looks good Details Reviewed-on: https://git.kske.dev/zdm/event-bus/pulls/34 Reviewed-by: delvh <leon@kske.dev>	2022-01-12 17:19:57 +01:00
Kai S. K. Engelbart	722bf2b999	Test priorities for inheritance zdm/event-bus/pipeline/head This commit looks good Details	2022-01-12 15:59:45 +01:00
Kai S. K. Engelbart	7fb633d69f	Inherit event handlers zdm/event-bus/pipeline/head This commit looks good Details When registering an event listener, Event Bus recursively walks the entire inheritance tree and looks for event handlers.	2022-01-09 14:16:30 +01:00
Kai S. K. Engelbart	c5607d12ae	Fix SonarQube scan zdm/event-bus/pipeline/head This commit looks good Details	2022-01-09 11:49:10 +01:00
Kai S. K. Engelbart	a8810c497f	Merge pull request 'Jenkinsfile with SonarQube Analysis' (#33 ) from f/jenkinsfile into develop zdm/event-bus/pipeline/head There was a failure building this commit Details Reviewed-on: https://git.kske.dev/zdm/event-bus/pulls/33 Reviewed-by: delvh <leon@kske.dev>	2022-01-09 11:32:25 +01:00
Kai S. K. Engelbart	ebb2191f4a	Make unit tests package-private zdm/event-bus/pipeline/head This commit looks good Details	2022-01-09 09:37:27 +01:00
Kai S. K. Engelbart	09d251a02a	Add Jenkinsfile zdm/event-bus/pipeline/head This commit looks good Details The Jenkinsfile performs packaging and testing on the project. When on the develop branch, a SonarQube analysis is conducted.	2022-01-09 09:27:44 +01:00
Kai S. K. Engelbart	27d14a844d	Merge pull request 'Exception Wrapper' (#32 ) from f/exception-wrapper into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/32 Reviewed-by: delvh <leon@kske.dev> Reviewed-by: DieGurke <maxi@kske.dev>	2022-01-08 16:54:05 +01:00
Leon Hofmeister	adbcc64e94	Add ExceptionWrapper documentation	2022-01-08 16:44:49 +01:00
Maximilian P. Käfer	84ae42b44f	Remove unnecessary new line	2022-01-08 15:02:35 +01:00
Kai S. K. Engelbart	e53f356c54	Add exception wrapper with transparent delivery to the caller	2022-01-08 14:32:24 +01:00
Kai S. K. Engelbart	d649f377b7	Merge pull request 'Shorten Module Names' (#30 ) from f/improve-project-structure into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/30 Reviewed-by: delvh <leon@kske.dev>	2021-12-24 13:57:16 +01:00
Kai S. K. Engelbart	897f1a20f3	Shorten module names	2021-12-24 11:09:14 +02:00
Kai S. K. Engelbart	856a2e8cbf	Bump version to 1.2.0	2021-11-26 15:54:37 +01:00
Kai S. K. Engelbart	11860d1469	Merge pull request 'Document Latest Features in README' (#27 ) from f/improved-readme into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/27 Reviewed-by: delvh <leon@kske.dev>	2021-11-26 13:54:58 +01:00
Kai S. K. Engelbart	f620f06208	Merge branch 'develop' into f/improved-readme Conflicts: event-bus-core/src/test/java/dev/kske/eventbus/core/DispatchTest.java	2021-11-25 14:36:07 +01:00
Kai S. K. Engelbart	5a6d8bcf35	Rename EventBus#printExecutionOrder(Class) to debugExecutionOrder The method doesn't print anything, but rather returns a string containing the debug information.	2021-11-25 14:34:13 +01:00
Kai S. K. Engelbart	39ffb5c82a	Fix module-info instructions in README Reflective access has to be allowed from the Event Bus core package to a package in the user's project, not the entire module. Thank you @delvh for noticing this!	2021-11-25 14:29:06 +01:00
Kai S. K. Engelbart	5ddef71c26	Merge pull request 'Support JDK-style Javadoc Tags' (#28 ) from b/javadoc-tags into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/28 Reviewed-by: delvh <leon@kske.dev>	2021-11-25 12:05:32 +01:00
Kai S. K. Engelbart	85b2da391a	Merge pull request 'Make Unit Tests Executable by Maven' (#29 ) from b/unit-test-execution into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/29 Reviewed-by: delvh <leon@kske.dev>	2021-11-25 12:04:26 +01:00
Kai S. K. Engelbart	46a358da97	Make unit tests executable by Maven	2021-11-24 12:52:59 +01:00
Kai S. K. Engelbart	6bf9e1097a	Support JDK-style Javadoc tags	2021-11-24 11:30:36 +01:00
Kai S. K. Engelbart	3fccb809c8	Move installation section up in README	2021-11-24 10:49:30 +01:00
Kai S. K. Engelbart	d1c4bcc7eb	Add callback listener section to README	2021-11-24 10:45:58 +01:00
Kai S. K. Engelbart	ad29a93ccb	Add debugging section to README	2021-11-24 10:37:21 +01:00
Kai S. K. Engelbart	e67b64678b	Merge pull request 'Add Callback Event Handling' (#26 ) from f/callback-handler into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/26 Reviewed-by: delvh <leon@kske.dev>	2021-11-05 08:49:07 +01:00
Kai S. K. Engelbart	c614beb063	Make CallbackEventHandler final	2021-11-04 15:55:24 +01:00
Kai S. K. Engelbart	d3abb0aca3	Improve parameter naming for listener registration	2021-11-04 15:54:36 +01:00
Kai S. K. Engelbart	ee688929fd	Add callback event handling The EventHandler class has been converted to an interface, with the reflection specific part being moved to the new ReflectiveEventHandler class. Callback event handlers implement the same interface through the CallbackEventHandler class. The event handlers are defined in the new handler package, which is not exported by the eventbus.core module.	2021-11-02 19:33:18 +01:00
Kai S. K. Engelbart	897d794b86	Merge pull request 'Handler Execution Order Debugging' (#25 ) from f/handler-introspection into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/25 Reviewed-by: delvh <leon@kske.dev>	2021-11-02 09:03:10 +01:00
Kai S. K. Engelbart	40d48cb959	Merge pull request 'Improve Documentation in Code' (#24 ) from f/improved-documentation into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/24 Reviewed-by: DieGurke <maxi@kske.dev>	2021-11-01 21:48:51 +01:00
Kai S. K. Engelbart	b760c58298	Add a handler execution order debugging method	2021-11-01 21:36:24 +01:00
Kai S. K. Engelbart	872b395374	Rephrase some Javadoc As suggested by @delvh.	2021-11-01 20:52:14 +01:00
Kai S. K. Engelbart	82c66c45ec	Improve EventBus Javadoc, make EventBusException final	2021-11-01 09:42:12 +01:00
Kai S. K. Engelbart	866a547114	Merge pull request 'Initialize the Default Event Bus Statically' (#23 ) from f/static-singleton-initialization into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/23 Reviewed-by: delvh <leon@kske.dev>	2021-10-16 08:33:08 +02:00
Kai S. K. Engelbart	33ebf0302b	Initialize the default event bus statically The previous method that used double checked synchronization offers little performance benefits over a plain static initialization. Reported-by @harkle-the-cake	2021-10-16 08:32:28 +02:00
Kai S. K. Engelbart	b915a5c490	Merge pull request 'Properly Handle Nested Dispatches' (#19 ) from b/nested-dispatch into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/19 Reviewed-by: delvh <leon@kske.dev>	2021-07-12 11:25:04 +02:00
Kai S. K. Engelbart	205a183db7	Allow nested dispatches by keeping track of nesting count	2021-07-12 10:24:48 +02:00
Kai S. K. Engelbart	74447dea59	Add nested dispatch test The test performs a nested event dispatch then cancels the dispatch. If Both operations are successful, the test is successful. Currently, the test fails, but should be successful once the nested dispatch bug is fixed.	2021-07-12 10:17:46 +02:00
Kai S. K. Engelbart	6eebd3c121	Pass errors caused during system event dispatch to caller When an error is caused during the dispatch of a system event, a warning has been logged instead instead of rethrowing the error. This has been fixed. This enables failing a JUnit test when an exception event handler is invoked.	2021-07-07 22:06:07 +02:00
Kai S. K. Engelbart	b758f4cef1	Remove obsolete paragraph from README	2021-04-04 10:09:12 +02:00
Kai S. K. Engelbart	0dcad7d178	Bump version to 1.1.0	2021-03-28 10:37:41 +02:00
Kai S. K. Engelbart	c0cda7341b	Merge pull request 'Add @delvh as Contributor' (#15 ) from add-delvh-as-contributor into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/15 Reviewed-by: delvh <leon@kske.dev>	2021-03-17 17:25:30 +01:00
Kai S. K. Engelbart	b804243f4e	Add @delvh as contributor	2021-03-17 13:10:20 +01:00
Kai S. K. Engelbart	0aef1c299b	Change license to Apache-2.0 This should allow for more compatibility with other Java applications, including proprietary ones.	2021-03-17 12:57:43 +01:00
Kai S. K. Engelbart	51f10c4144	Merge pull request 'Listener-Level Properties' (#13 ) from f/listener-level-properties into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/13 Reviewed-by: delvh <leon@kske.dev>	2021-03-17 07:56:22 +01:00
Kai S. K. Engelbart	f74b953db8	Replace hardcoded priority value by constant	2021-03-16 10:17:24 +01:00
Kai S. K. Engelbart	52719d22d4	Merge pull request 'Transparently Propagate Event Handler Errors' (#14 ) from b/error-passthrough into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/14 Reviewed-by: delvh <leon@kske.dev> Reviewed-by: DieGurke <maxi@kske.dev>	2021-03-16 08:17:41 +01:00
Kai S. K. Engelbart	122106bf39	Transparently propagate event handler errors When an exception occurs during the execution of an event handler, it is caught, wrapped inside an exception event and dispatched on the event bus. This applies to any throwable, but is not very useful for errors, as these are not normally caught. Assertion errors in particular, which are used in unit tests, should not be caught, as this would cause the test runner to miss a failed test. Therefore, errors are now transparently passed through to the caller of the dispatch method.	2021-03-15 08:29:15 +01:00
Kai S. K. Engelbart	7357198d45	Warn about useless handler property redefinitions When polymorphism or a priority is defined at listener-level and then identically defined for a specific handler, a warning is issued. This does not affect redefinitions of default values.	2021-03-14 14:38:43 +01:00
Kai S. K. Engelbart	32dfe64c0f	Add listener-level properties section to README	2021-03-14 11:44:56 +01:00
Kai S. K. Engelbart	2ec0a82a96	Respect listener-level properties	2021-03-14 11:18:11 +01:00
Kai S. K. Engelbart	6c74af608c	Allow @Polymorphic and @Priority on types, add value to @Polymorphic This is the first step for listener level handler properties. To allow a handler inside a polymorphic listener to be non-polymorphic, the @Polymorphic annotation now has a boolean value that defaults to true. In that case, it can be explicitly set to false to override the listener-level default.	2021-02-22 19:12:06 +01:00
Kai S. K. Engelbart	d9ddc0e1a9	Merge pull request 'Add ExceptionEvent' (#12 ) from f/exception-event into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/12 Reviewed-by: delvh <leon@kske.dev> Reviewed-by: DieGurke <maxi@kske.dev>	2021-02-21 14:04:26 +01:00
Kai S. K. Engelbart	7c3cd017de	Add system events section to README	2021-02-21 13:50:12 +01:00
Kai S. K. Engelbart	6a2cad4ae5	Add ExceptionEvent An exception event wraps an event that caused an exception inside of an event handler while being dispatched and is then dispatched to dedicated handlers.	2021-02-21 10:36:06 +01:00
Kai S. K. Engelbart	0f9b64be48	Merge pull request 'Add DeadEvent' (#9 ) from f/dead-event into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/9 Reviewed-by: delvh <leon@kske.dev> Reviewed-by: DieGurke <maxi@kske.dev>	2021-02-21 09:16:32 +01:00
Kai S. K. Engelbart	b2fe3a9d6c	Log unhandled dead events	2021-02-20 22:10:48 +01:00
Kai S. K. Engelbart	9379e6bb94	Merge pull request 'Additional Warnings in Event Bus Proc' (#8 ) from f/additional-warnings into develop Reviewed-on: https://git.kske.dev/kske/event-bus/pulls/8 Reviewed-by: delvh <leon@kske.dev>	2021-02-20 21:46:08 +01:00
Kai S. K. Engelbart	0036dc4829	Add DeadEvent A dead events wraps an event that was dispatched but not delivered to any handler. The dead event is than dispatched to dedicated handlers.	2021-02-19 16:05:11 +01:00
Kai S. K. Engelbart	8a30493c52	Warn about unused event handler return values If an event handler has a non-void return type, a warning is issued as the event bus cannot use the returned value. In rare cases this might be justified as the event handler could be invoked directly.	2021-02-19 11:34:58 +01:00
Kai S. K. Engelbart	b56f08e441	Warn about unnecessarily polymorphic event handlers When Event Bus Proc detects a handler for a final type that uses the @Polymorphic annotation, it issues a warning.	2021-02-19 11:30:09 +01:00