From 6d07a7c2fa547ff5ad24d1b192e9fc84eadfe845 Mon Sep 17 00:00:00 2001
From: Player <sfPlayer1@users.noreply.github.com>
Date: Sun, 14 Feb 2021 17:41:08 +0000
Subject: [PATCH] Make event registration thread safe (#1305)
(cherry picked from commit be996d2566ad2f23321b9343ac08a06080d57ab2)
---
.../net/fabricmc/fabric/api/event/Event.java | 2 +-
.../impl/base/event/ArrayBackedEvent.java | 29 ++++++++++++-------
2 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/fabric-api-base/src/main/java/net/fabricmc/fabric/api/event/Event.java b/fabric-api-base/src/main/java/net/fabricmc/fabric/api/event/Event.java
index c3c652f6f..8016d5db2 100644
--- a/fabric-api-base/src/main/java/net/fabricmc/fabric/api/event/Event.java
+++ b/fabric-api-base/src/main/java/net/fabricmc/fabric/api/event/Event.java
@@ -28,7 +28,7 @@ public abstract class Event<T> {
* always refer to an instance containing all code that should be
* executed upon event emission.
*/
- protected T invoker;
+ protected volatile T invoker;
/**
* Returns the invoker instance.
diff --git a/fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/ArrayBackedEvent.java b/fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/ArrayBackedEvent.java
index bc62e358b..99c1ecebf 100644
--- a/fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/ArrayBackedEvent.java
+++ b/fabric-api-base/src/main/java/net/fabricmc/fabric/impl/base/event/ArrayBackedEvent.java
@@ -18,6 +18,8 @@ package net.fabricmc.fabric.impl.base.event;
import java.lang.reflect.Array;
import java.util.Arrays;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Function;
import net.fabricmc.fabric.api.event.Event;
@@ -26,6 +28,7 @@ class ArrayBackedEvent<T> extends Event<T> {
private final Class<? super T> type;
private final Function<T[], T> invokerFactory;
private final T dummyInvoker;
+ private final Lock lock = new ReentrantLock();
private T[] handlers;
ArrayBackedEvent(Class<? super T> type, T dummyInvoker, Function<T[], T> invokerFactory) {
@@ -35,12 +38,12 @@ class ArrayBackedEvent<T> extends Event<T> {
update();
}
+ @SuppressWarnings("unchecked")
void update() {
if (handlers == null) {
if (dummyInvoker != null) {
invoker = dummyInvoker;
} else {
- //noinspection unchecked
invoker = invokerFactory.apply((T[]) Array.newInstance(type, 0));
}
} else if (handlers.length == 1) {
@@ -50,21 +53,27 @@ class ArrayBackedEvent<T> extends Event<T> {
}
}
+ @SuppressWarnings("unchecked")
@Override
public void register(T listener) {
if (listener == null) {
throw new NullPointerException("Tried to register a null listener!");
}
- if (handlers == null) {
- //noinspection unchecked
- handlers = (T[]) Array.newInstance(type, 1);
- handlers[0] = listener;
- } else {
- handlers = Arrays.copyOf(handlers, handlers.length + 1);
- handlers[handlers.length - 1] = listener;
- }
+ lock.lock();
- update();
+ try {
+ if (handlers == null) {
+ handlers = (T[]) Array.newInstance(type, 1);
+ handlers[0] = listener;
+ } else {
+ handlers = Arrays.copyOf(handlers, handlers.length + 1);
+ handlers[handlers.length - 1] = listener;
+ }
+
+ update();
+ } finally {
+ lock.unlock();
+ }
}
}