WW-5355 Initial Caffeine cache implementation

core/pom.xml

@@ -184,6 +184,11 @@
             <artifactId>freemarker</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>com.github.ben-manes.caffeine</groupId>
+            <artifactId>caffeine</artifactId>
+        </dependency>
+
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>

core/src/main/java/com/opensymphony/xwork2/ognl/OgnlCaffeineCache.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2022 Apache Software Foundation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.opensymphony.xwork2.ognl;
+
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
+
+/**
+ * <p>This OGNL Cache implementation is backed by {@link Caffeine} which uses the Window TinyLfu algorithm.</p>
+ *
+ * <p>An appropriate eviction limit should be chosen for your specific application based on factors and requirements
+ * such as:</p>
+ * <ul>
+ *     <li>Quantity and complexity of actions</li>
+ *     <li>Volume of requests</li>
+ *     <li>Rate limits and attack potential/patterns</li>
+ *     <li>Memory constraints</li>
+ * </ul>
+ *
+ * @param <Key>   The type for the cache key entries
+ * @param <Value> The type for the cache value entries
+ */
+public class OgnlCaffeineCache<Key, Value> implements OgnlCache<Key, Value> {
+
+    private final Cache<Key, Value> cache;
+    private final int evictionLimit;
+
+    public OgnlCaffeineCache(int evictionLimit, int initialCapacity, float loadFactor) {
+        this.evictionLimit = evictionLimit;
+        this.cache = Caffeine.newBuilder().initialCapacity(initialCapacity).maximumSize(evictionLimit).build();
+    }
+
+    @Override
+    public Value get(Key key) {
+        return cache.getIfPresent(key);
+    }
+
+    @Override
+    public void put(Key key, Value value) {
+        cache.put(key, value);
+    }
+
+    @Override
+    public void putIfAbsent(Key key, Value value) {
+        if (cache.getIfPresent(key) == null) {
+            cache.put(key, value);
+        }
+    }
+
+    @Override
+    public int size() {
+        return Math.toIntExact(cache.estimatedSize());
+    }
+
+    @Override
+    public void clear() {
+        cache.invalidateAll();
+    }
+
+    @Override
+    public int getEvictionLimit() {
+        return evictionLimit;
+    }
+
+    @Override
+    public void setEvictionLimit(int cacheEvictionLimit) {
+        throw new UnsupportedOperationException("Cannot change eviction limit on a Caffeine cache after initialisation");
+    }
+}

pom.xml

@@ -685,6 +685,12 @@
                 <version>${freemarker.version}</version>
             </dependency>
 
+            <dependency>
+                <groupId>com.github.ben-manes.caffeine</groupId>
+                <artifactId>caffeine</artifactId>
+                <version>3.1.8</version>
+            </dependency>
+
             <dependency>
                 <groupId>org.apache.felix</groupId>
                 <artifactId>org.apache.felix.framework</artifactId>