Waterfall/fire-pit/0016-Use-ASM-for-events-via-the-Event4J-library.patch

From 86c5823b0bfdfc21e38850b46bb486c4e10e940c Mon Sep 17 00:00:00 2001
From: Techcable <Techcable@outlook.com>
Date: Sun, 28 Feb 2016 22:46:22 -0700
Subject: [PATCH] Use ASM for events, via the Event4J library

According to benchmarks, this is about 7 nanoseconds faster than reflection (34 ns -> 27 ns).
Event4J falls back to Java 8's new MethodHandle if the event method isn't public.

diff --git a/event/pom.xml b/event/pom.xml
index b6ef990..ff72600 100644
--- a/event/pom.xml
+++ b/event/pom.xml
@@ -17,4 +17,24 @@
 
     <name>Waterfall-Event</name>
     <description>Generic java event dispatching API intended for use with Waterfall.</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>net.techcable</groupId>
+            <artifactId>event4j</artifactId>
+            <version>1.1.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.ow2.asm</groupId>
+            <artifactId>asm-all</artifactId>
+            <version>5.0.4</version>
+        </dependency>
+    </dependencies>
+
+    <repositories>
+        <repository>
+            <id>techcable-repo</id>
+            <url>https://repo.techcable.net/content/groups/public/</url>
+        </repository>
+    </repositories>
 </project>
diff --git a/event/src/main/java/net/md_5/bungee/event/EventBus.java b/event/src/main/java/net/md_5/bungee/event/EventBus.java
index 5b5d420..c93aa16 100644
--- a/event/src/main/java/net/md_5/bungee/event/EventBus.java
+++ b/event/src/main/java/net/md_5/bungee/event/EventBus.java
@@ -1,26 +1,13 @@
 package net.md_5.bungee.event;
 
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import java.text.MessageFormat;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
-import java.util.logging.Level;
 import java.util.logging.Logger;
 
 public class EventBus
 {
 
-    private final Map<Class<?>, Map<Byte, Map<Object, Method[]>>> byListenerAndPriority = new HashMap<>();
-    private final Map<Class<?>, EventHandlerMethod[]> byEventBaked = new ConcurrentHashMap<>();
-    private final Lock lock = new ReentrantLock();
+    private final net.techcable.event4j.EventBus<Object, Object> event4JBus = net.techcable.event4j.EventBus.builder()
+            .eventMarker((m) -> m.isAnnotationPresent(EventHandler.class) ? m.getAnnotation(EventHandler.class)::priority : null)
+            .build();
     private final Logger logger;
 
     public EventBus()
@@ -35,167 +22,16 @@ public class EventBus
 
     public void post(Object event)
     {
-        EventHandlerMethod[] handlers = byEventBaked.get( event.getClass() );
-
-        if ( handlers != null )
-        {
-            for ( EventHandlerMethod method : handlers )
-            {
-                try
-                {
-                    method.invoke( event );
-                } catch ( IllegalAccessException ex )
-                {
-                    throw new Error( "Method became inaccessible: " + event, ex );
-                } catch ( IllegalArgumentException ex )
-                {
-                    throw new Error( "Method rejected target/argument: " + event, ex );
-                } catch ( InvocationTargetException ex )
-                {
-                    logger.log( Level.WARNING, MessageFormat.format( "Error dispatching event {0} to listener {1}", event, method.getListener() ), ex.getCause() );
-                }
-            }
-        }
-    }
-
-    private Map<Class<?>, Map<Byte, Set<Method>>> findHandlers(Object listener)
-    {
-        Map<Class<?>, Map<Byte, Set<Method>>> handler = new HashMap<>();
-        for ( Method m : listener.getClass().getDeclaredMethods() )
-        {
-            EventHandler annotation = m.getAnnotation( EventHandler.class );
-            if ( annotation != null )
-            {
-                Class<?>[] params = m.getParameterTypes();
-                if ( params.length != 1 )
-                {
-                    logger.log( Level.INFO, "Method {0} in class {1} annotated with {2} does not have single argument", new Object[]
-                    {
-                        m, listener.getClass(), annotation
-                    } );
-                    continue;
-                }
-                Map<Byte, Set<Method>> prioritiesMap = handler.get( params[0] );
-                if ( prioritiesMap == null )
-                {
-                    prioritiesMap = new HashMap<>();
-                    handler.put( params[0], prioritiesMap );
-                }
-                Set<Method> priority = prioritiesMap.get( annotation.priority() );
-                if ( priority == null )
-                {
-                    priority = new HashSet<>();
-                    prioritiesMap.put( annotation.priority(), priority );
-                }
-                priority.add( m );
-            }
-        }
-        return handler;
+        event4JBus.fire(event);
     }
 
     public void register(Object listener)
     {
-        Map<Class<?>, Map<Byte, Set<Method>>> handler = findHandlers( listener );
-        lock.lock();
-        try
-        {
-            for ( Map.Entry<Class<?>, Map<Byte, Set<Method>>> e : handler.entrySet() )
-            {
-                Map<Byte, Map<Object, Method[]>> prioritiesMap = byListenerAndPriority.get( e.getKey() );
-                if ( prioritiesMap == null )
-                {
-                    prioritiesMap = new HashMap<>();
-                    byListenerAndPriority.put( e.getKey(), prioritiesMap );
-                }
-                for ( Map.Entry<Byte, Set<Method>> entry : e.getValue().entrySet() )
-                {
-                    Map<Object, Method[]> currentPriorityMap = prioritiesMap.get( entry.getKey() );
-                    if ( currentPriorityMap == null )
-                    {
-                        currentPriorityMap = new HashMap<>();
-                        prioritiesMap.put( entry.getKey(), currentPriorityMap );
-                    }
-                    Method[] baked = new Method[ entry.getValue().size() ];
-                    currentPriorityMap.put( listener, entry.getValue().toArray( baked ) );
-                }
-                bakeHandlers( e.getKey() );
-            }
-        } finally
-        {
-            lock.unlock();
-        }
+        event4JBus.register(listener);
     }
 
     public void unregister(Object listener)
     {
-        Map<Class<?>, Map<Byte, Set<Method>>> handler = findHandlers( listener );
-        lock.lock();
-        try
-        {
-            for ( Map.Entry<Class<?>, Map<Byte, Set<Method>>> e : handler.entrySet() )
-            {
-                Map<Byte, Map<Object, Method[]>> prioritiesMap = byListenerAndPriority.get( e.getKey() );
-                if ( prioritiesMap != null )
-                {
-                    for ( Byte priority : e.getValue().keySet() )
-                    {
-                        Map<Object, Method[]> currentPriority = prioritiesMap.get( priority );
-                        if ( currentPriority != null )
-                        {
-                            currentPriority.remove( listener );
-                            if ( currentPriority.isEmpty() )
-                            {
-                                prioritiesMap.remove( priority );
-                            }
-                        }
-                    }
-                    if ( prioritiesMap.isEmpty() )
-                    {
-                        byListenerAndPriority.remove( e.getKey() );
-                    }
-                }
-                bakeHandlers( e.getKey() );
-            }
-        } finally
-        {
-            lock.unlock();
-        }
-    }
-
-    /**
-     * Shouldn't be called without first locking the writeLock; intended for use
-     * only inside {@link #register(java.lang.Object) register(Object)} or
-     * {@link #unregister(java.lang.Object) unregister(Object)}.
-     */
-    private void bakeHandlers(Class<?> eventClass)
-    {
-        Map<Byte, Map<Object, Method[]>> handlersByPriority = byListenerAndPriority.get( eventClass );
-        if ( handlersByPriority != null )
-        {
-            List<EventHandlerMethod> handlersList = new ArrayList<>( handlersByPriority.size() * 2 );
-
-            // Either I'm really tired, or the only way we can iterate between Byte.MIN_VALUE and Byte.MAX_VALUE inclusively,
-            // with only a byte on the stack is by using a do {} while() format loop.
-            byte value = Byte.MIN_VALUE;
-            do
-            {
-                Map<Object, Method[]> handlersByListener = handlersByPriority.get( value );
-                if ( handlersByListener != null )
-                {
-                    for ( Map.Entry<Object, Method[]> listenerHandlers : handlersByListener.entrySet() )
-                    {
-                        for ( Method method : listenerHandlers.getValue() )
-                        {
-                            EventHandlerMethod ehm = new EventHandlerMethod( listenerHandlers.getKey(), method );
-                            handlersList.add( ehm );
-                        }
-                    }
-                }
-            } while ( value++ < Byte.MAX_VALUE );
-            byEventBaked.put( eventClass, handlersList.toArray( new EventHandlerMethod[ handlersList.size() ] ) );
-        } else
-        {
-            byEventBaked.remove( eventClass );
-        }
+        event4JBus.unregister(listener);
     }
 }
diff --git a/event/src/main/java/net/md_5/bungee/event/EventHandlerMethod.java b/event/src/main/java/net/md_5/bungee/event/EventHandlerMethod.java
deleted file mode 100644
index ad19c02..0000000
--- a/event/src/main/java/net/md_5/bungee/event/EventHandlerMethod.java
+++ /dev/null
@@ -1,21 +0,0 @@
-package net.md_5.bungee.event;
-
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import lombok.AllArgsConstructor;
-import lombok.Getter;
-
-@AllArgsConstructor
-public class EventHandlerMethod
-{
-
-    @Getter
-    private final Object listener;
-    @Getter
-    private final Method method;
-
-    public void invoke(Object event) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException
-    {
-        method.invoke( listener, event );
-    }
-}
-- 
2.8.3