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.format.bti;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  
  import org.apache.cassandra.db.DecoratedKey;
  import org.apache.cassandra.db.PartitionPosition;
  import org.apache.cassandra.dht.IPartitioner;
  import org.apache.cassandra.io.sstable.KeyReader;
  import org.apache.cassandra.io.sstable.format.Version;
  import org.apache.cassandra.io.util.FileDataInput;
  import org.apache.cassandra.io.util.FileHandle;
  import org.apache.cassandra.utils.ByteBufferUtil;
  import org.apache.cassandra.utils.Throwables;
  
  import static org.apache.cassandra.utils.FBUtilities.immutableListWithFilteredNulls;
  
  /**
   * Partition iterator for the BTI format.
   * <p>
   * As the index stores prefixes of keys, the slice returned by the underlying {@link PartitionIndex.IndexPosIterator}
   * may start and end with entries that have the same prefix as the provided bounds, but be in the wrong relationship
   * with them. To filter these out, we start by checking the first item during initialization, and by working one item
   * ahead, so that we can recognize the end of the slice and check the last item before we return it.
   */
  class PartitionIterator extends PartitionIndex.IndexPosIterator implements KeyReader
  {
      private final PartitionIndex partitionIndex;
      private final IPartitioner partitioner;
      private final PartitionPosition limit;
      private final int exclusiveLimit;
      private final FileHandle dataFile;
      private final FileHandle rowIndexFile;
      private final Version version;
  
      private FileDataInput dataInput;
      private FileDataInput indexInput;
  
      private DecoratedKey currentKey;
      private TrieIndexEntry currentEntry;
      private DecoratedKey nextKey;
      private TrieIndexEntry nextEntry;
  
      static PartitionIterator create(PartitionIndex partitionIndex, IPartitioner partitioner, FileHandle rowIndexFile, FileHandle dataFile,
                                      PartitionPosition left, int inclusiveLeft, PartitionPosition right, int exclusiveRight, Version version) throws IOException
      {
          PartitionIterator partitionIterator = null;
          PartitionIndex partitionIndexCopy = null;
          FileHandle dataFileCopy = null;
          FileHandle rowIndexFileCopy = null;
  
          try
          {
              partitionIndexCopy = partitionIndex.sharedCopy();
              dataFileCopy = dataFile.sharedCopy();
              rowIndexFileCopy = rowIndexFile.sharedCopy();
  
              partitionIterator = new PartitionIterator(partitionIndexCopy, partitioner, rowIndexFileCopy, dataFileCopy, left, right, exclusiveRight, version);
  
              partitionIterator.readNext();
              // Because the index stores prefixes, the first value can be in any relationship with the left bound.
              if (partitionIterator.nextKey != null && !(partitionIterator.nextKey.compareTo(left) > inclusiveLeft))
              {
                  partitionIterator.readNext();
              }
              partitionIterator.advance();
              return partitionIterator;
          }
          catch (IOException | RuntimeException ex)
          {
              if (partitionIterator != null)
              {
                  partitionIterator.close();
              }
              else
              {
                  Throwables.closeNonNullAndAddSuppressed(ex, rowIndexFileCopy, dataFileCopy, partitionIndexCopy);
              }
              throw ex;
          }
      }
  
      static PartitionIterator create(PartitionIndex partitionIndex, IPartitioner partitioner, FileHandle rowIndexFile, FileHandle dataFile, Version version) throws IOException
      {
          return create(partitionIndex, partitioner, rowIndexFile, dataFile, partitionIndex.firstKey(), -1, partitionIndex.lastKey(), 0, version);
      }
  
      static PartitionIterator empty(PartitionIndex partitionIndex)
      {
          return new PartitionIterator(partitionIndex.sharedCopy(), null);
      }
  
      private PartitionIterator(PartitionIndex partitionIndex, IPartitioner partitioner, FileHandle rowIndexFile, FileHandle dataFile,
                                PartitionPosition left, PartitionPosition right, int exclusiveRight, Version version)
      {
          super(partitionIndex, left, right);
          this.partitionIndex = partitionIndex;
          this.partitioner = partitioner;
          this.limit = right;
          this.exclusiveLimit = exclusiveRight;
          this.rowIndexFile = rowIndexFile;
          this.dataFile = dataFile;
          this.version = version;
      }
  
      private PartitionIterator(PartitionIndex partitionIndex, Version version)
      {
          super(partitionIndex, partitionIndex.firstKey(), partitionIndex.firstKey());
          this.partitionIndex = partitionIndex;
          this.partitioner = null;
          this.limit = partitionIndex.firstKey();
          this.exclusiveLimit = -1;
          this.rowIndexFile = null;
          this.dataFile = null;
  
          this.currentEntry = null;
          this.currentKey = null;
          this.nextEntry = null;
          this.nextKey = null;
          this.version = version;
      }
  
      @Override
      public void close()
      {
          Throwable accum = null;
          accum = Throwables.close(accum, immutableListWithFilteredNulls(partitionIndex, dataFile, rowIndexFile));
          accum = Throwables.close(accum, immutableListWithFilteredNulls(dataInput, indexInput));
          accum = Throwables.perform(accum, super::close);
          Throwables.maybeFail(accum);
      }
  
      public DecoratedKey decoratedKey()
      {
          return currentKey;
      }
  
      public ByteBuffer key()
      {
          return currentKey.getKey();
      }
  
      @Override
      public long dataPosition()
      {
          return currentEntry != null ? currentEntry.position : -1;
      }
  
      @Override
      public long keyPositionForSecondaryIndex()
      {
          return dataPosition();
      }
  
      public TrieIndexEntry entry()
      {
          return currentEntry;
      }
  
      @Override
      public boolean advance() throws IOException
      {
          currentKey = nextKey;
          currentEntry = nextEntry;
          if (currentKey != null)
          {
              readNext();
              // if nextKey is null, then currentKey is the last key to be published, therefore check against any limit
              // and suppress the partition if it is beyond the limit
              if (nextKey == null && limit != null && currentKey.compareTo(limit) > exclusiveLimit)
              {   // exclude last partition outside range
                  currentKey = null;
                  currentEntry = null;
                  return false;
              }
              return true;
          }
          return false;
      }
  
      private void readNext() throws IOException
      {
          long pos = nextIndexPos();
          if (pos != PartitionIndex.NOT_FOUND)
          {
              if (pos >= 0)
              {
                  seekIndexInput(pos);
                  nextKey = partitioner.decorateKey(ByteBufferUtil.readWithShortLength(indexInput));
                  nextEntry = TrieIndexEntry.deserialize(indexInput, indexInput.getFilePointer(), version);
              }
              else
              {
                  pos = ~pos;
                  seekDataInput(pos);
                  nextKey = partitioner.decorateKey(ByteBufferUtil.readWithShortLength(dataInput));
                  nextEntry = new TrieIndexEntry(pos);
              }
          }
          else
          {
              nextKey = null;
              nextEntry = null;
          }
      }
  
      private void seekIndexInput(long pos) throws IOException
      {
          if (indexInput == null)
              indexInput = rowIndexFile.createReader(pos);
          else
              indexInput.seek(pos);
      }
  
      private void seekDataInput(long pos) throws IOException
      {
          if (dataInput == null)
              dataInput = dataFile.createReader(pos);
          else
              dataInput.seek(pos);
      }
  
      @Override
      public boolean isExhausted()
      {
          return currentKey == null;
      }
  
      @Override
      public void reset()
      {
          go(root);
      }
  
      @Override
      public String toString()
      {
          return String.format("BTI-PartitionIterator(%s)", partitionIndex.getFileHandle().path());
      }
  }
  