Remove MRUCache

Now we're using ConcurrentHashMap, it's usefulness in terms of performance is debatable

common/src/main/java/me/lucko/luckperms/common/cache/MRUCache.java

@@ -1,66 +0,0 @@
-/*
- * 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.cache;
-
-import java.util.concurrent.atomic.AtomicInteger;
-
-/**
- * Implementation of a most-recently-used cache with a mod counter, to prevent race conditions
- * occurring when the cache is cleared whilst a calculation is taking place.
- *
- * @param <T> the cached type
- */
-public abstract class MRUCache<T> {
-    private volatile T recent;
-    private final AtomicInteger modCount = new AtomicInteger();
-
-    protected int modCount() {
-        return this.modCount.get();
-    }
-
-    protected T getRecent() {
-        return this.recent;
-    }
-
-    protected void offerRecent(int validAt, T offer) {
-        synchronized (this) {
-            if (validAt == this.modCount.get()) {
-                this.recent = offer;
-            }
-        }
-    }
-
-    /**
-     * Calling clearRecent effectively resets the instance. any other threads going to call
-     * offerRecent in the future with the previous mod count will be ignored.
-     */
-    protected void clearRecent() {
-        synchronized (this) {
-            this.recent = null;
-            this.modCount.incrementAndGet();
-        }
-    }
-}

common/src/main/java/me/lucko/luckperms/common/cacheddata/AbstractCachedDataManager.java

@@ -26,7 +26,6 @@
 package me.lucko.luckperms.common.cacheddata;
 
 import me.lucko.luckperms.common.cache.LoadingMap;
-import me.lucko.luckperms.common.cache.MRUCache;
 import me.lucko.luckperms.common.cacheddata.type.MetaAccumulator;
 import me.lucko.luckperms.common.cacheddata.type.MetaCache;
 import me.lucko.luckperms.common.cacheddata.type.PermissionCache;
@@ -183,7 +182,7 @@ public abstract class AbstractCachedDataManager implements CachedDataManager {
         this.meta.cleanup();
     }
 
-    private static final class AbstractContainer<C extends I, I extends CachedData> extends MRUCache<RecentData<C>> implements Container<I> {
+    private static final class AbstractContainer<C extends I, I extends CachedData> implements Container<I> {
         private final Function<QueryOptions, C> cacheLoader;
         private final LoadingMap<QueryOptions, C> cache;
 
@@ -200,16 +199,8 @@ public abstract class AbstractCachedDataManager implements CachedDataManager {
         public @NonNull C get(@NonNull QueryOptions queryOptions) {
             Objects.requireNonNull(queryOptions, "queryOptions");
 
-            RecentData<C> recent = getRecent();
-            if (recent != null && queryOptions.equals(recent.queryOptions)) {
-                ((UsageTracked) recent.data).recordUsage();
-                return recent.data;
-            }
-
-            int modCount = modCount();
             C data = this.cache.get(queryOptions);
             ((UsageTracked) data).recordUsage();
-            offerRecent(modCount, new RecentData<>(queryOptions, data));
             return data;
         }
 
@@ -225,7 +216,6 @@ public abstract class AbstractCachedDataManager implements CachedDataManager {
             CompletableFuture.runAsync(() -> {
                 final C value = this.cacheLoader.apply(queryOptions);
                 this.cache.put(queryOptions, value);
-                clearRecent();
             }, CaffeineFactory.executor());
         }
 
@@ -235,14 +225,9 @@ public abstract class AbstractCachedDataManager implements CachedDataManager {
 
             // invalidate the previous value until we're done recalculating
             this.cache.remove(queryOptions);
-            clearRecent();
 
             // request recalculation from the cache
-            return CompletableFuture.supplyAsync(() -> {
+            return CompletableFuture.supplyAsync(() -> this.cache.get(queryOptions), CaffeineFactory.executor());
-                C value = this.cache.get(queryOptions);
-                clearRecent();
-                return value;
-            }, CaffeineFactory.executor());
         }
 
         @Override
@@ -261,13 +246,11 @@ public abstract class AbstractCachedDataManager implements CachedDataManager {
         public void invalidate(@NonNull QueryOptions queryOptions) {
             Objects.requireNonNull(queryOptions, "queryOptions");
             this.cache.remove(queryOptions);
-            clearRecent();
         }
 
         @Override
         public void invalidate() {
             this.cache.clear();
-            clearRecent();
         }
     }
 
@@ -291,14 +274,4 @@ public abstract class AbstractCachedDataManager implements CachedDataManager {
         );
     }
 
-    private static final class RecentData<T> {
-        final QueryOptions queryOptions;
-        final T data;
-
-        RecentData(QueryOptions queryOptions, T data) {
-            this.queryOptions = queryOptions;
-            this.data = data;
-        }
-    }
-
 }