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;
  
  import java.util.concurrent.Callable;
  
  /**
   * Cache method collection definition.
   * @author zzq
   * @date 2021/7/30
   */
  public interface Cache<K, V> {
  
      /**
       * Cache a pair of key value. If the key value already exists, the value will be overwritten.
       * @param key cache key
       * @param val cache value
       */
      void put(K key, V val);
      
      /**
       * Take the corresponding value from the cache according to the cache key.
       * @param key cache key
       * @return cache value
       */
      V get(K key);
      
      /**
       * Get the value in the cache according to the primary key, and put it into the cache after processing by the function.
       * @param key cache key
       * @param call a function, the return value of the function will be updated to the cache
       * @return cache value
       * @throws Exception callable function interface throw exception
       */
      V get(K key, Callable<? extends V> call) throws Exception;
      
      /**
       * Take the corresponding value from the cache according to the cache key, and remove this record from the cache.
       * @param key cache key
       * @return cache value
       */
      V remove(K key);
      
      /**
       * Clear the entire cache.
       */
      void clear();
      
      /**
       * Returns the number of key-value pairs in the cache.
       * @return  number of key-value pairs
       */
      int getSize();
  }
  