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.index.sai.disk.v1.trie;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import javax.annotation.concurrent.NotThreadSafe;
  
  import org.apache.cassandra.io.tries.SerializationNode;
  import org.apache.cassandra.io.tries.TrieNode;
  import org.apache.cassandra.io.tries.TrieSerializer;
  import org.apache.cassandra.io.tries.Walker;
  import org.apache.cassandra.io.util.DataOutputPlus;
  import org.apache.cassandra.io.util.Rebufferer;
  import org.apache.cassandra.io.util.SizedInts;
  import org.apache.cassandra.utils.bytecomparable.ByteComparable;
  import org.apache.cassandra.utils.bytecomparable.ByteSource;
  
  /**
   * Page-aware random access reader for a trie terms dictionary written by {@link TrieTermsDictionaryWriter}.
   */
  @NotThreadSafe
  public class TrieTermsDictionaryReader extends Walker<TrieTermsDictionaryReader>
  {
      public static final long NOT_FOUND = -1;
  
      public TrieTermsDictionaryReader(Rebufferer rebufferer, long root)
      {
          super(rebufferer, root);
      }
  
      public static final TrieSerializer<Long, DataOutputPlus> trieSerializer = new TrieSerializer<>()
      {
          @Override
          public int sizeofNode(SerializationNode<Long> node, long nodePosition)
          {
              return TrieNode.typeFor(node, nodePosition).sizeofNode(node) + sizeof(node.payload());
          }
  
          @Override
          public void write(DataOutputPlus dest, SerializationNode<Long> node, long nodePosition) throws IOException
          {
              TrieNode type = TrieNode.typeFor(node, nodePosition);
              Long payload = node.payload();
              int payloadBits = sizeof(payload);
              type.serialize(dest, node, payloadBits, nodePosition);
  
              if (payload != null)
                  SizedInts.write(dest, payload, payloadBits);
          }
  
          private int sizeof(Long payload)
          {
              return payload == null ? 0 : SizedInts.nonZeroSize(payload);
          }
      };
  
      public long exactMatch(ByteComparable key)
      {
          // Since we are looking for an exact match we are always expecting the follow
          // to return END_OF_STREAM if the key was found.
          return follow(key) == ByteSource.END_OF_STREAM ? getCurrentPayload() : NOT_FOUND;
      }
  
      private long getCurrentPayload()
      {
          return getPayloadAt(buf, payloadPosition(), payloadFlags());
      }
  
      private long getPayloadAt(ByteBuffer contents, int payloadPos, int bytes)
      {
          if (bytes == 0)
          {
              return NOT_FOUND;
          }
          return SizedInts.read(contents, payloadPos, bytes);
      }
  }
  