3 files changed, 28 insertions, 3 deletions
diff --git a/src/main/java/org/bukkit/plugin/PluginManager.java b/src/main/java/org/bukkit/plugin/PluginManager.java
index 804f4415..89697de8 100644
--- a/src/main/java/org/bukkit/plugin/PluginManager.java
+++ b/src/main/java/org/bukkit/plugin/PluginManager.java
@@ -92,8 +92,11 @@ public interface PluginManager {
      * Calls an event with the given details
      *
      * @param event Event details
+     * @throws IllegalStateException Thrown when an asynchronous event is fired from synchronous code.<br>
+     *          <i>Note: This is best-effort basis, and should not be used to test synchronized state. This
+     *          is an indicator for flawed flow logic.</i>
      */
-    public void callEvent(Event event);
+    public void callEvent(Event event) throws IllegalStateException;
 
     /**
      * Registers all the events in the given listener class
diff --git a/src/main/java/org/bukkit/plugin/SimplePluginManager.java b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
index e017ffdf..ca780fca 100644
--- a/src/main/java/org/bukkit/plugin/SimplePluginManager.java
+++ b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
@@ -443,11 +443,28 @@ public final class SimplePluginManager implements PluginManager {
     }
 
     /**
-     * Calls an event with the given details
+     * Calls an event with the given details.<br>
+     * This method only synchronizes when the event is not asynchronous.
      *
      * @param event Event details
      */
-    public synchronized void callEvent(Event event) {
+    public void callEvent(Event event) {
+        if (event.isAsynchronous()) {
+            if (Thread.holdsLock(this)) {
+                throw new IllegalStateException(event.getEventName() + " cannot be triggered asynchronously from inside synchronized code.");
+            }
+            if (server.isPrimaryThread()) {
+                throw new IllegalStateException(event.getEventName() + " cannot be triggered asynchronously from primary server thread.");
+            }
+            fireEvent(event);
+        } else {
+            synchronized (this) {
+                fireEvent(event);
+            }
+        }
+    }
+
+    private void fireEvent(Event event) {
         HandlerList handlers = event.getHandlers();
         RegisteredListener[] listeners = handlers.getRegisteredListeners();
 
diff --git a/src/main/java/org/bukkit/plugin/TimedRegisteredListener.java b/src/main/java/org/bukkit/plugin/TimedRegisteredListener.java
index 53dfde38..ed25e179 100644
--- a/src/main/java/org/bukkit/plugin/TimedRegisteredListener.java
+++ b/src/main/java/org/bukkit/plugin/TimedRegisteredListener.java
@@ -18,7 +18,12 @@ public class TimedRegisteredListener extends RegisteredListener {
         super(pluginListener, eventExecutor, eventPriority, registeredPlugin, listenCancelled);
     }
 
+    @Override
     public void callEvent(Event event) throws EventException {
+        if (event.isAsynchronous()) {
+            super.callEvent(event);
+            return;
+        }
         count++;
         if (this.event == null) {
             this.event = event;