content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.nacos.common.cache.decorators;
  
  import com.alibaba.nacos.common.cache.Cache;
  import com.alibaba.nacos.common.cache.builder.CacheItemProperties;
  
  import java.util.HashMap;
  import java.util.concurrent.Callable;
  
  /**
   * A wrapper that automatically expires the cache.
   *
   * @author zzq
   * @date 2021/7/30
   */
  public class AutoExpireCache<K, V> implements Cache<K, V> {
      
      private long expireNanos;
      
      private Cache<K, V> delegate;
      
      private HashMap<K, CacheItemProperties> keyProp = new HashMap<>();
      
      public AutoExpireCache(Cache<K, V> delegate, long expireNanos) {
          this.expireNanos = expireNanos;
          this.delegate = delegate;
      }
      
      @Override
      public void put(K key, V val) {
          keyProp.put(key, cacheItemProperties());
          this.delegate.put(key, val);
      }
      
      @Override
      public V get(K key) {
          CacheItemProperties itemProperties = keyProp.get(key);
          if (itemProperties != null && isExpire(itemProperties)) {
              this.keyProp.remove(key);
              this.delegate.remove(key);
              return null;
          }
          return this.delegate.get(key);
      }
      
      @Override
      public V get(K key, Callable<? extends V> call) throws Exception {
          V cachedValue = this.get(key);
          if (null == cachedValue) {
              V v2 = call.call();
              this.put(key, v2);
              return v2;
              
          }
          return cachedValue;
          
      }
      
      @Override
      public V remove(K key) {
          keyProp.remove(key);
          return this.delegate.remove(key);
      }
      
      @Override
      public void clear() {
          keyProp.clear();
          this.delegate.clear();
      }
      
      @Override
      public int getSize() {
          return this.delegate.getSize();
      }
      
      private boolean isExpire(CacheItemProperties itemProperties) {
          return expireNanos != -1 && (System.nanoTime() - itemProperties.getExpireNanos() > expireNanos);
      }
      
      private CacheItemProperties cacheItemProperties() {
          CacheItemProperties cacheItemProperties = new CacheItemProperties();
          cacheItemProperties.setExpireNanos(System.nanoTime());
          return cacheItemProperties;
      }
  }
  