123 lines
5.0 KiB
Diff
123 lines
5.0 KiB
Diff
From 77036b521bed13898c2987f64afdf0b260b60548 Mon Sep 17 00:00:00 2001
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From: Aikar <aikar@aikar.co>
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Date: Sun, 9 Sep 2018 00:32:05 -0400
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Subject: [PATCH] Remove deadlock risk in firing async events
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The PluginManager incorrectly used synchronization on firing any event
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that was marked as synchronous.
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This synchronized did not even protect any concurrency risk as
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handlers were already thread safe in terms of mutations during event
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dispatch.
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The way it was used, has commonly led to deadlocks on the server,
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which results in a hard crash.
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This change removes the synchronize and adds some protection around enable/disable
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diff --git a/src/main/java/org/bukkit/plugin/SimplePluginManager.java b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
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index cb2b0b9cb..a7dd902fb 100644
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--- a/src/main/java/org/bukkit/plugin/SimplePluginManager.java
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+++ b/src/main/java/org/bukkit/plugin/SimplePluginManager.java
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@@ -385,7 +385,7 @@ public final class SimplePluginManager implements PluginManager {
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* @param plugin Plugin to check
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* @return true if the plugin is enabled, otherwise false
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*/
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- public boolean isPluginEnabled(Plugin plugin) {
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+ public synchronized boolean isPluginEnabled(Plugin plugin) { // Paper - synchronize
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if ((plugin != null) && (plugins.contains(plugin))) {
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return plugin.isEnabled();
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} else {
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@@ -393,7 +393,7 @@ public final class SimplePluginManager implements PluginManager {
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}
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}
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- public void enablePlugin(final Plugin plugin) {
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+ public synchronized void enablePlugin(final Plugin plugin) { // Paper - synchronize
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if (!plugin.isEnabled()) {
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List<Command> pluginCommands = PluginCommandYamlParser.parse(plugin);
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@@ -430,7 +430,7 @@ public final class SimplePluginManager implements PluginManager {
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disablePlugin(plugin, false);
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}
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- public void disablePlugin(final Plugin plugin, boolean closeClassloader) {
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+ public synchronized void disablePlugin(final Plugin plugin, boolean closeClassloader) { // Paper - synchronize
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// Paper end - close Classloader on disable
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if (plugin.isEnabled()) {
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try {
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@@ -490,6 +490,7 @@ public final class SimplePluginManager implements PluginManager {
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defaultPerms.get(false).clear();
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}
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}
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+ private void fireEvent(Event event) { callEvent(event); } // Paper - support old method incase plugin uses reflection
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/**
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* Calls an event with the given details.
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@@ -499,22 +500,7 @@ public final class SimplePluginManager implements PluginManager {
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* @param event Event details
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*/
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public void callEvent(Event event) {
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- if (event.isAsynchronous()) {
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- if (Thread.holdsLock(this)) {
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- throw new IllegalStateException(event.getEventName() + " cannot be triggered asynchronously from inside synchronized code.");
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- }
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- if (server.isPrimaryThread()) {
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- throw new IllegalStateException(event.getEventName() + " cannot be triggered asynchronously from primary server thread.");
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- }
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- fireEvent(event);
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- } else {
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- synchronized (this) {
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- fireEvent(event);
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- }
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- }
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- }
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-
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- private void fireEvent(Event event) {
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+ // Paper - replace callEvent by merging to below method
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HandlerList handlers = event.getHandlers();
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RegisteredListener[] listeners = handlers.getRegisteredListeners();
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diff --git a/src/test/java/org/bukkit/plugin/PluginManagerTest.java b/src/test/java/org/bukkit/plugin/PluginManagerTest.java
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index 6b86128e1..56308c0c6 100644
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--- a/src/test/java/org/bukkit/plugin/PluginManagerTest.java
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+++ b/src/test/java/org/bukkit/plugin/PluginManagerTest.java
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@@ -19,7 +19,7 @@ public class PluginManagerTest {
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private static final PluginManager pm = TestServer.getInstance().getPluginManager();
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private final MutableObject store = new MutableObject();
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-
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+/* // Paper start - remove unneeded test
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@Test
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public void testAsyncSameThread() {
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final Event event = new TestEvent(true);
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@@ -30,14 +30,14 @@ public class PluginManagerTest {
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return;
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}
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throw new IllegalStateException("No exception thrown");
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- }
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+ }*/ // Paper end
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@Test
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public void testSyncSameThread() {
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final Event event = new TestEvent(false);
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pm.callEvent(event);
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}
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-
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+/* // Paper start - remove unneeded test
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@Test
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public void testAsyncLocked() throws InterruptedException {
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final Event event = new TestEvent(true);
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@@ -58,7 +58,7 @@ public class PluginManagerTest {
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secondThread.join();
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assertThat(store.value, is(instanceOf(IllegalStateException.class)));
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assertThat(event.getEventName() + " cannot be triggered asynchronously from inside synchronized code.", is(((Throwable) store.value).getMessage()));
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- }
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+ }*/ // Paper end
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@Test
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public void testAsyncUnlocked() throws InterruptedException {
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--
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2.18.0
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