content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.kafka.common.security.authenticator;
  
  import java.util.concurrent.ConcurrentHashMap;
  
  public class CredentialCache {
  
      private final ConcurrentHashMap<String, Cache<?>> cacheMap = new ConcurrentHashMap<>();
  
      public <C> Cache<C> createCache(String mechanism, Class<C> credentialClass) {
          Cache<C> cache = new Cache<>(credentialClass);
          @SuppressWarnings("unchecked")
          Cache<C> oldCache = (Cache<C>) cacheMap.putIfAbsent(mechanism, cache);
          return oldCache == null ? cache : oldCache;
      }
  
      @SuppressWarnings("unchecked")
      public <C> Cache<C> cache(String mechanism, Class<C> credentialClass) {
          Cache<?> cache = cacheMap.get(mechanism);
          if (cache != null) {
              if (cache.credentialClass() != credentialClass)
                  throw new IllegalArgumentException("Invalid credential class " + credentialClass + ", expected " + cache.credentialClass());
              return (Cache<C>) cache;
          } else
              return null;
      }
  
      public static class Cache<C> {
          private final Class<C> credentialClass;
          private final ConcurrentHashMap<String, C> credentials;
  
          public Cache(Class<C> credentialClass) {
              this.credentialClass = credentialClass;
              this.credentials = new ConcurrentHashMap<>();
          }
  
          public C get(String username) {
              return credentials.get(username);
          }
  
          public C put(String username, C credential) {
              return credentials.put(username, credential);
          }
  
          public C remove(String username) {
              return credentials.remove(username);
          }
  
          public Class<C> credentialClass() {
              return credentialClass;
          }
      }
  }
  