1 files changed, 137 insertions, 0 deletions
diff --git a/Spigot-API-Patches-Unmapped/0129-Remove-deadlock-risk-in-firing-async-events.patch b/Spigot-API-Patches-Unmapped/0129-Remove-deadlock-risk-in-firing-async-events.patch
new file mode 100644
index 0000000000..2725c79f2e
--- /dev/null
+++ b/Spigot-API-Patches-Unmapped/0129-Remove-deadlock-risk-in-firing-async-events.patch
@@ -0,0 +1,137 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <[email protected]>
+Date: Sun, 9 Sep 2018 00:32:05 -0400
+Subject: [PATCH] Remove deadlock risk in firing async events
+
+The PluginManager incorrectly used synchronization on firing any event
+that was marked as synchronous.
+
+This synchronized did not even protect any concurrency risk as
+handlers were already thread safe in terms of mutations during event
+dispatch.
+
+The way it was used, has commonly led to deadlocks on the server,
+which results in a hard crash.
+
+This change removes the synchronize and adds some protection around enable/disable
+
+diff --git a/src/main/java/org/bukkit/entity/Entity.java b/src/main/java/org/bukkit/entity/Entity.java
+index 9b8823279524d1c1566176c589aa5794eb8aafbc..707638c327077a74c777a603b9f2392f46b51c0c 100644
+--- a/src/main/java/org/bukkit/entity/Entity.java
++++ b/src/main/java/org/bukkit/entity/Entity.java
+@@ -28,7 +28,7 @@ import org.jetbrains.annotations.Nullable;
+  */
+ public interface Entity extends Metadatable, CommandSender, Nameable, PersistentDataHolder, net.kyori.adventure.text.event.HoverEventSource<net.kyori.adventure.text.event.HoverEvent.ShowEntity> { // Paper
+ 
+-    /**
++    /*
+      * Gets the entity's current position
+      *
+      * @return a new copy of Location containing the position of this entity
+diff --git a/src/main/java/org/bukkit/plugin/SimplePluginManager.java b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
+index a7393d2830b95d7167121b02066a3f357cee6085..a1a805004941d67abb0b9aa1721e0370c45b5289 100644
+--- a/src/main/java/org/bukkit/plugin/SimplePluginManager.java
++++ b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
+@@ -462,7 +462,7 @@ public final class SimplePluginManager implements PluginManager {
+      * @return true if the plugin is enabled, otherwise false
+      */
+     @Override
+-    public boolean isPluginEnabled(@Nullable Plugin plugin) {
++    public synchronized boolean isPluginEnabled(@Nullable Plugin plugin) { // Paper - synchronize
+         if ((plugin != null) && (plugins.contains(plugin))) {
+             return plugin.isEnabled();
+         } else {
+@@ -471,7 +471,7 @@ public final class SimplePluginManager implements PluginManager {
+     }
+ 
+     @Override
+-    public void enablePlugin(@NotNull final Plugin plugin) {
++    public synchronized void enablePlugin(@NotNull final Plugin plugin) { // Paper - synchronize
+         if (!plugin.isEnabled()) {
+             List<Command> pluginCommands = PluginCommandYamlParser.parse(plugin);
+ 
+@@ -509,7 +509,7 @@ public final class SimplePluginManager implements PluginManager {
+     }
+ 
+     @Override
+-    public void disablePlugin(@NotNull final Plugin plugin, boolean closeClassloader) {
++    public synchronized void disablePlugin(@NotNull final Plugin plugin, boolean closeClassloader) { // Paper - synchronize
+         // Paper end - close Classloader on disable
+         if (plugin.isEnabled()) {
+             try {
+@@ -579,6 +579,7 @@ public final class SimplePluginManager implements PluginManager {
+             defaultPerms.get(false).clear();
+         }
+     }
++    private void fireEvent(Event event) { callEvent(event); } // Paper - support old method incase plugin uses reflection
+ 
+     /**
+      * Calls an event with the given details.
+@@ -587,23 +588,13 @@ public final class SimplePluginManager implements PluginManager {
+      */
+     @Override
+     public void callEvent(@NotNull 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.");
+-            }
+-        } else {
+-            if (!server.isPrimaryThread()) {
+-                throw new IllegalStateException(event.getEventName() + " cannot be triggered asynchronously from another thread.");
+-            }
++        // Paper - replace callEvent by merging to below method
++        if (event.isAsynchronous() && server.isPrimaryThread()) {
++            throw new IllegalStateException(event.getEventName() + " may only be triggered asynchronously.");
++        } else if (!event.isAsynchronous() && !server.isPrimaryThread()) {
++            throw new IllegalStateException(event.getEventName() + " may only be triggered synchronously.");
+         }
+ 
+-        fireEvent(event);
+-    }
+-
+-    private void fireEvent(@NotNull Event event) {
+         HandlerList handlers = event.getHandlers();
+         RegisteredListener[] listeners = handlers.getRegisteredListeners();
+ 
+diff --git a/src/test/java/org/bukkit/plugin/PluginManagerTest.java b/src/test/java/org/bukkit/plugin/PluginManagerTest.java
+index f188cd4f3b07027c30d41f1162db77a506b7b6bb..1941c9f49e9514c1236c5f4ea9f7af47f7be85c5 100644
+--- a/src/test/java/org/bukkit/plugin/PluginManagerTest.java
++++ b/src/test/java/org/bukkit/plugin/PluginManagerTest.java
+@@ -17,7 +17,7 @@ public class PluginManagerTest {
+     private static final PluginManager pm = TestServer.getInstance().getPluginManager();
+ 
+     private final MutableObject store = new MutableObject();
+-
++/* // Paper start - remove unneeded test
+     @Test
+     public void testAsyncSameThread() {
+         final Event event = new TestEvent(true);
+@@ -28,14 +28,14 @@ public class PluginManagerTest {
+             return;
+         }
+         throw new IllegalStateException("No exception thrown");
+-    }
++    }*/ // Paper end
+ 
+     @Test
+     public void testSyncSameThread() {
+         final Event event = new TestEvent(false);
+         pm.callEvent(event);
+     }
+-
++/* // Paper start - remove unneeded test
+     @Test
+     public void testAsyncLocked() throws InterruptedException {
+         final Event event = new TestEvent(true);
+@@ -129,7 +129,7 @@ public class PluginManagerTest {
+         if (store.value == null) {
+             throw new IllegalStateException("No exception thrown");
+         }
+-    }
++    } */ // Paper
+ 
+     @Test
+     public void testRemovePermissionByNameLower() {