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.segment;
  
  import java.io.IOException;
  import java.util.Map;
  
  import com.google.common.base.MoreObjects;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.db.PartitionPosition;
  import org.apache.cassandra.dht.AbstractBounds;
  import org.apache.cassandra.index.sai.QueryContext;
  import org.apache.cassandra.index.sai.StorageAttachedIndex;
  import org.apache.cassandra.index.sai.disk.PrimaryKeyMap;
  import org.apache.cassandra.index.sai.disk.format.IndexComponent;
  import org.apache.cassandra.index.sai.disk.v1.PerColumnIndexFiles;
  import org.apache.cassandra.index.sai.disk.v1.SAICodecUtils;
  import org.apache.cassandra.index.sai.iterators.KeyRangeIterator;
  import org.apache.cassandra.index.sai.metrics.MulticastQueryEventListeners;
  import org.apache.cassandra.index.sai.metrics.QueryEventListener;
  import org.apache.cassandra.index.sai.plan.Expression;
  import org.apache.cassandra.utils.bytecomparable.ByteComparable;
  
  /**
   * Executes {@link Expression}s against the trie-based terms dictionary for an individual index segment.
   */
  public class LiteralIndexSegmentSearcher extends IndexSegmentSearcher
  {
      private static final Logger logger = LoggerFactory.getLogger(LiteralIndexSegmentSearcher.class);
  
      private final LiteralIndexSegmentTermsReader reader;
      private final QueryEventListener.TrieIndexEventListener perColumnEventListener;
  
      LiteralIndexSegmentSearcher(PrimaryKeyMap.Factory primaryKeyMapFactory,
                                  PerColumnIndexFiles perIndexFiles,
                                  SegmentMetadata segmentMetadata,
                                  StorageAttachedIndex index) throws IOException
      {
          super(primaryKeyMapFactory, perIndexFiles, segmentMetadata, index);
  
          long root = metadata.getIndexRoot(IndexComponent.TERMS_DATA);
          assert root >= 0;
  
          perColumnEventListener = (QueryEventListener.TrieIndexEventListener)index.columnQueryMetrics();
  
          Map<String,String> map = metadata.componentMetadatas.get(IndexComponent.TERMS_DATA).attributes;
          String footerPointerString = map.get(SAICodecUtils.FOOTER_POINTER);
          long footerPointer = footerPointerString == null ? -1 : Long.parseLong(footerPointerString);
  
          reader = new LiteralIndexSegmentTermsReader(index.identifier(), indexFiles.termsData(), indexFiles.postingLists(), root, footerPointer);
      }
  
      @Override
      public long indexFileCacheSize()
      {
          // trie has no pre-allocated memory.
          return 0;
      }
  
      @Override
      public KeyRangeIterator search(Expression expression, AbstractBounds<PartitionPosition> keyRange, QueryContext queryContext) throws IOException
      {
          if (logger.isTraceEnabled())
              logger.trace(index.identifier().logMessage("Searching on expression '{}'..."), expression);
  
          if (!expression.getIndexOperator().isEquality())
              throw new IllegalArgumentException(index.identifier().logMessage("Unsupported expression: " + expression));
  
          ByteComparable term = v -> index.termType().asComparableBytes(expression.lower().value.encoded, v);
          QueryEventListener.TrieIndexEventListener listener = MulticastQueryEventListeners.of(queryContext, perColumnEventListener);
          return toPrimaryKeyIterator(reader.exactMatch(term, listener, queryContext), queryContext);
      }
  
      @Override
      public String toString()
      {
          return MoreObjects.toStringHelper(this).add("index", index).toString();
      }
  
      @Override
      public void close()
      {
          reader.close();
      }
  }
  