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/*
 * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
 * under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership. Camunda licenses this file to you under the Apache License,
 * Version 2.0; 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 org.camunda.commons.utils.cache;

import java.util.Set;

/**
 * A Map-like data structure that stores key-value pairs and provides temporary
 * access to it.
 *
 * @param  the type of keys
 * @param  the type of mapped values
 */
public interface Cache {

  /**
   * Gets an entry from the cache.
   *
   * @param key the key whose associated value is to be returned
   * @return the element, or null, if it does not exist.
   */
  V get(K key);

  /**
   * Associates the specified value with the specified key in the cache.
   *
   * @param key   key with which the specified value is to be associated
   * @param value value to be associated with the specified key
   * @throws NullPointerException if key is null or if value is null
   */
  void put(K key, V value);

  /**
   * Clears the contents of the cache.
   */
  void clear();

  /**
   * Removes an entry from the cache.
   *
   * @param key key with which the specified value is to be associated.
   */
  void remove(K key);

  /**
   * Returns a Set view of the keys contained in this cache.
   */
  public Set keySet();

  /**
   * @return the current size of the cache
   */
  public int size();

  /**
   * Returns true if this cache contains no key-value mappings.
   */
  public boolean isEmpty();

}