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.io.sstable.keycache;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  
  import org.apache.cassandra.cache.KeyCacheKey;
  import org.apache.cassandra.db.ClusteringBound;
  import org.apache.cassandra.db.DecoratedKey;
  import org.apache.cassandra.io.sstable.AbstractRowIndexEntry;
  import org.apache.cassandra.io.sstable.format.SSTableFormat;
  import org.apache.cassandra.io.sstable.format.SSTableReader;
  import org.apache.cassandra.io.util.DataInputPlus;
  
  public interface KeyCacheSupport<T extends SSTableReader & KeyCacheSupport<T>>
  {
      @Nonnull
      KeyCache getKeyCache();
  
      /**
       * Should quickly get a lower bound prefix from cache only if everything is already availabe in memory and does not
       * need to be loaded from disk.
       */
      @Nullable
      ClusteringBound<?> getLowerBoundPrefixFromCache(DecoratedKey partitionKey, boolean isReversed);
  
      default @Nonnull KeyCacheKey getCacheKey(ByteBuffer key)
      {
          T reader = (T) this;
          return new KeyCacheKey(reader.metadata(), reader.descriptor, key);
      }
  
      default @Nonnull KeyCacheKey getCacheKey(DecoratedKey key)
      {
          return getCacheKey(key.getKey());
      }
  
      /**
       * Will return null if key is not found or cache is not available.
       */
      default @Nullable AbstractRowIndexEntry getCachedPosition(DecoratedKey key, boolean updateStats)
      {
          return getCachedPosition(getCacheKey(key), updateStats);
      }
  
      /**
       * Will return null if key is not found or cache is not available.
       */
      default @Nullable AbstractRowIndexEntry getCachedPosition(KeyCacheKey key, boolean updateStats)
      {
          KeyCache keyCache = getKeyCache();
          AbstractRowIndexEntry cachedEntry = keyCache.get(key, updateStats);
          assert cachedEntry == null || cachedEntry.getSSTableFormat() == ((T) this).descriptor.version.format;
  
          return cachedEntry;
      }
  
      /**
       * Caches a key only if cache is available.
       */
      default void cacheKey(@Nonnull DecoratedKey key, @Nonnull AbstractRowIndexEntry info)
      {
          T reader = (T) this;
          assert info.getSSTableFormat() == reader.descriptor.version.format;
  
          KeyCacheKey cacheKey = getCacheKey(key);
          getKeyCache().put(cacheKey, info);
      }
  
      @Nonnull
      AbstractRowIndexEntry deserializeKeyCacheValue(@Nonnull DataInputPlus input) throws IOException;
  
      static boolean isSupportedBy(SSTableFormat<?, ?> format)
      {
          return KeyCacheSupport.class.isAssignableFrom(format.getReaderFactory().getReaderClass());
      }
  
  }
  