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.cassandra.auth;
  
  import java.util.Set;
  import java.util.function.BiPredicate;
  import java.util.function.BooleanSupplier;
  
  import com.github.benmanes.caffeine.cache.LoadingCache;
  import com.google.common.annotations.VisibleForTesting;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.service.StorageService;
  
  public class CacheRefresher<K, V> implements Runnable
  {
      private static final Logger logger = LoggerFactory.getLogger(CacheRefresher.class);
  
      private final String name;
      private final LoadingCache<K, V> cache;
      private final BiPredicate<K, V> invalidationCondition;
      private final BooleanSupplier skipCondition;
  
      private CacheRefresher(String name, LoadingCache<K, V> cache,  BiPredicate<K, V> invalidationCondition, BooleanSupplier skipCondition)
      {
          this.name = name;
          this.cache = cache;
          this.invalidationCondition = invalidationCondition;
          this.skipCondition = skipCondition;
      }
  
      public void run()
      {
          if (skipCondition.getAsBoolean())
          {
              logger.debug("Skipping {} cache refresh", name);
              return;
          }
  
          try
          {
              logger.debug("Refreshing {} cache", name);
              Set<K> ks = cache.asMap().keySet();
              for (K key : ks)
              {
                  cache.refresh(key);
                  V value = cache.getIfPresent(key);
                  if (invalidationCondition.test(key, value))
                  {
                      logger.debug("Invalidating key");
                      cache.invalidate(key);
                  }
              }
          }
          catch (Exception e)
          {
              logger.error("Unexpected exception refreshing {} cache", name, e);
          }
      }
  
      @VisibleForTesting
      public static <K, V> CacheRefresher<K, V> create(String name,
                                                       LoadingCache<K, V> cache,
                                                       BiPredicate<K, V> invalidationCondition,
                                                       BooleanSupplier skipCondition)
      {
          logger.info("Creating CacheRefresher for {}", name);
          return new CacheRefresher<>(name, cache, invalidationCondition, skipCondition);
      }
  
      public static <K, V> CacheRefresher<K, V> create(String name, LoadingCache<K, V> cache, BiPredicate<K, V> invalidationCondition)
      {
          // By default we skip cache refreshes if the node has been decommed
          return create(name, cache, invalidationCondition, StorageService.instance::isDecommissioned);
      }
  }