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.Closeable;
  import java.io.IOException;
  import java.util.List;
  
  import com.google.common.annotations.VisibleForTesting;
  
  import org.apache.cassandra.db.PartitionPosition;
  import org.apache.cassandra.dht.AbstractBounds;
  import org.apache.cassandra.dht.Range;
  import org.apache.cassandra.dht.Token;
  import org.apache.cassandra.index.sai.QueryContext;
  import org.apache.cassandra.index.sai.SSTableContext;
  import org.apache.cassandra.index.sai.StorageAttachedIndex;
  import org.apache.cassandra.index.sai.disk.PrimaryKeyMap;
  import org.apache.cassandra.index.sai.disk.v1.PerColumnIndexFiles;
  import org.apache.cassandra.index.sai.iterators.KeyRangeIterator;
  import org.apache.cassandra.index.sai.plan.Expression;
  import org.apache.cassandra.index.sai.utils.PrimaryKey;
  import org.apache.cassandra.io.util.FileUtils;
  
  /**
   * Each segment represents an on-disk index structure (balanced tree/terms/postings) flushed by memory limit or token boundaries.
   * It also helps to reduce resource consumption for read requests as only segments that intersect with read request data
   * range need to be loaded.
   */
  public class Segment implements SegmentOrdering, Closeable
  {
      private final Token.KeyBound minKeyBound;
      private final Token.KeyBound maxKeyBound;
  
      // per sstable
      final PrimaryKeyMap.Factory primaryKeyMapFactory;
      // per-segment
      public final SegmentMetadata metadata;
  
      private final IndexSegmentSearcher index;
  
      public Segment(StorageAttachedIndex index, SSTableContext sstableContext, PerColumnIndexFiles indexFiles, SegmentMetadata metadata) throws IOException
      {
          this.minKeyBound = metadata.minKey.token().minKeyBound();
          this.maxKeyBound = metadata.maxKey.token().maxKeyBound();
  
          this.primaryKeyMapFactory = sstableContext.primaryKeyMapFactory;
          this.metadata = metadata;
  
          this.index = IndexSegmentSearcher.open(primaryKeyMapFactory, indexFiles, metadata, index);
      }
  
      @VisibleForTesting
      public Segment(Token minKey, Token maxKey)
      {
          this.primaryKeyMapFactory = null;
          this.metadata = null;
          this.minKeyBound = minKey.minKeyBound();
          this.maxKeyBound = maxKey.maxKeyBound();
          this.index = null;
      }
  
      /**
       * @return true if current segment intersects with query key range
       */
      public boolean intersects(AbstractBounds<PartitionPosition> keyRange)
      {
          if (keyRange instanceof Range && ((Range<?>)keyRange).isWrapAround())
              return keyRange.contains(minKeyBound) || keyRange.contains(maxKeyBound);
  
          int cmp = keyRange.right.compareTo(minKeyBound);
          // if right is minimum, it means right is the max token and bigger than maxKey.
          // if right bound is less than minKeyBound, no intersection
          if (!keyRange.right.isMinimum() && (!keyRange.inclusiveRight() && cmp == 0 || cmp < 0))
              return false;
  
          cmp = keyRange.left.compareTo(maxKeyBound);
          // if left bound is bigger than maxKeyBound, no intersection
          return (keyRange.isStartInclusive() || cmp != 0) && cmp <= 0;
      }
  
      public long indexFileCacheSize()
      {
          return index == null ? 0 : index.indexFileCacheSize();
      }
  
      /**
       * Search on-disk index synchronously
       *
       * @param expression to filter on disk index
       * @param context to track per sstable cache and per query metrics
  
       * @return range iterator that matches given expression
       */
      public KeyRangeIterator search(Expression expression, AbstractBounds<PartitionPosition> keyRange, QueryContext context) throws IOException
      {
          return index.search(expression, keyRange, context);
      }
  
      @Override
      public KeyRangeIterator limitToTopKResults(QueryContext context, List<PrimaryKey> primaryKeys, Expression expression) throws IOException
      {
          return index.limitToTopKResults(context, primaryKeys, expression);
      }
  
      @Override
      public void close()
      {
          FileUtils.closeQuietly(index);
      }
  
      @Override
      public String toString()
      {
          return String.format("Segment{metadata=%s}", metadata);
      }
  }
  