/*
 * $Id$
 *
 * This file is part of the Cloud Services Integration Platform (CSIP),
 * a Model-as-a-Service framework, API and application suite.
 *
 * 2012-2022, Olaf David and others, OMSLab, Colorado State University.
 *
 * OMSLab licenses this file to you under the MIT license.
 * See the LICENSE file in the project root for more information.
 */
package csip.utils;

import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;

/**
 * Simple, non-evicting cache. Good for Resource caching.
 *
 * @author od
 * @param <K> generic key
 * @param <V> generic value
 */
public class SimpleCache<K, V> extends ConcurrentHashMap<K, V> {

  private static final long serialVersionUID = 1L;


  /**
   * Get the cache entry. If not present, the Function f will be invoked to
   * create one.
   *
   * @param k the key
   * @param f the Function to create the value
   * @return the cache value
   */
  public synchronized V get(K k, Function<K, V> f) {
    V v = get(k);
    if (v == null && f != null)
      put(k, v = f.apply(k));

    return v;
  }
}