Paper/Spigot-API-Patches/0196-Make-JavaPluginLoader-thread-safe.patch

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From 49584133dc28884b641698f3b8996b0b1d60642c Mon Sep 17 00:00:00 2001
From: Trigary <trigary0@gmail.com>
Date: Wed, 15 Apr 2020 01:24:55 -0400
Subject: [PATCH] Make JavaPluginLoader thread-safe
diff --git a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
index 8ff228ced..ba2c5c6ee 100644
--- a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
+++ b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
@@ -52,6 +52,8 @@ public final class JavaPluginLoader implements PluginLoader {
final Server server;
private final Pattern[] fileFilters = new Pattern[]{Pattern.compile("\\.jar$")};
private final Map<String, Class<?>> classes = new ConcurrentHashMap<String, Class<?>>();
+ private final Map<String, java.util.concurrent.locks.ReentrantReadWriteLock> classLoadLock = new java.util.HashMap<String, java.util.concurrent.locks.ReentrantReadWriteLock>(); // Paper
+ private final Map<String, Integer> classLoadLockCount = new java.util.HashMap<String, Integer>(); // Paper
private final List<PluginClassLoader> loaders = new CopyOnWriteArrayList<PluginClassLoader>();
/**
@@ -191,7 +193,19 @@ public final class JavaPluginLoader implements PluginLoader {
@Nullable
Class<?> getClassByName(final String name) {
+ // Paper start - make MT safe
Class<?> cachedClass = classes.get(name);
+ if (cachedClass != null) {
+ return cachedClass;
+ }
+ java.util.concurrent.locks.ReentrantReadWriteLock lock;
+ synchronized (classLoadLock) {
+ lock = classLoadLock.computeIfAbsent(name, (x) -> new java.util.concurrent.locks.ReentrantReadWriteLock());
+ classLoadLockCount.compute(name, (x, prev) -> prev != null ? prev + 1 : 1);
+ }
+ lock.writeLock().lock();try {
+ cachedClass = classes.get(name);
+ // Paper end
if (cachedClass != null) {
return cachedClass;
@@ -205,6 +219,19 @@ public final class JavaPluginLoader implements PluginLoader {
}
}
}
+ // Paper start - make MT safe
+ } finally {
+ synchronized (classLoadLock) {
+ lock.writeLock().unlock();
+ if (classLoadLockCount.get(name) == 1) {
+ classLoadLock.remove(name);
+ classLoadLockCount.remove(name);
+ } else {
+ classLoadLockCount.compute(name, (x, prev) -> prev - 1);
+ }
+ }
+ }
+ // Paper end
return null;
}
--
2.26.2