Refactor the way contexts are cached on all platforms (#1071)

Should fix memory leak issues on BungeeCord

common/src/main/java/me/lucko/luckperms/common/contexts/ContextManager.java

@@ -25,8 +25,6 @@
 
 package me.lucko.luckperms.common.contexts;
 
-import com.github.benmanes.caffeine.cache.Caffeine;
-import com.github.benmanes.caffeine.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 
 import me.lucko.luckperms.api.Contexts;
@@ -62,12 +60,6 @@ public abstract class ContextManager<T> {
     private final List<ContextCalculator<? super T>> calculators = new CopyOnWriteArrayList<>();
     private final List<StaticContextCalculator> staticCalculators = new CopyOnWriteArrayList<>();
 
-    // caches the creation of cache instances. cache-ception.
-    // we want to encourage re-use of these instances, it's faster that way
-    private final LoadingCache<T, ContextsCache<T>> subjectCaches = Caffeine.newBuilder()
-            .weakKeys()
-            .build(key -> new ContextsCache<>(key, this));
-
     // caches static context lookups
     private final StaticLookupCache staticLookupCache = new StaticLookupCache();
 
@@ -129,12 +121,7 @@ public abstract class ContextManager<T> {
      * @param subject the subject
      * @return the cache
      */
-    public ContextsCache<T> getCacheFor(T subject) {
-        if (subject == null) {
-            throw new NullPointerException("subject");
-        }
-        return this.subjectCaches.get(subject);
-    }
+    public abstract ContextsSupplier getCacheFor(T subject);
 
     /**
      * Gets the contexts from the static calculators in this manager.
@@ -228,18 +215,9 @@ public abstract class ContextManager<T> {
      *
      * @param subject the subject
      */
-    public void invalidateCache(T subject) {
-        if (subject == null) {
-            throw new NullPointerException("subject");
-        }
+    public abstract void invalidateCache(T subject);
 
-        ContextsCache<T> cache = this.subjectCaches.getIfPresent(subject);
-        if (cache != null) {
-            cache.invalidate();
-        }
-    }
-
-    Contexts calculate(T subject) {
+    protected Contexts calculate(T subject) {
         MutableContextSet accumulator = MutableContextSet.create();
 
         for (ContextCalculator<? super T> calculator : ContextManager.this.calculators) {

common/src/main/java/me/lucko/luckperms/common/contexts/ContextsCache.java

@@ -34,12 +34,11 @@ import java.util.concurrent.TimeUnit;
 import javax.annotation.Nonnull;
 
 /**
- * Extension of {@link ContextManager} that implements an expiring lookup cache
- * per player.
+ * Implementation of {@link ContextsSupplier} that caches results.
  *
  * @param <T> the player type
  */
-public final class ContextsCache<T> extends ExpiringCache<Contexts> {
+public final class ContextsCache<T> extends ExpiringCache<Contexts> implements ContextsSupplier {
     private final T subject;
     private final ContextManager<T> contextManager;
 
@@ -55,10 +54,12 @@ public final class ContextsCache<T> extends ExpiringCache<Contexts> {
         return this.contextManager.calculate(this.subject);
     }
 
+    @Override
     public Contexts getContexts() {
         return get();
     }
 
+    @Override
     public ImmutableContextSet getContextSet() {
         // this is actually already immutable, but the Contexts method signature returns the interface.
         // using the makeImmutable method is faster than casting

common/src/main/java/me/lucko/luckperms/common/contexts/ContextsSupplier.java

@@ -0,0 +1,40 @@
+/*
+ * This file is part of LuckPerms, licensed under the MIT License.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+package me.lucko.luckperms.common.contexts;
+
+import me.lucko.luckperms.api.Contexts;
+import me.lucko.luckperms.api.context.ImmutableContextSet;
+
+/**
+ * Supplies contexts for a given subject.
+ */
+public interface ContextsSupplier {
+
+    Contexts getContexts();
+
+    ImmutableContextSet getContextSet();
+
+}