package org.apache.cassandra.db.columniterator;
/*
*
* 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.
*
*/
import java.io.IOError;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.List;
import com.google.common.collect.AbstractIterator;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.db.ColumnFamily;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.db.IColumn;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.io.sstable.IndexHelper;
import org.apache.cassandra.io.util.FileDataInput;
import org.apache.cassandra.io.util.FileMark;
import org.apache.cassandra.io.sstable.SSTableReader;
/**
* This is a reader that finds the block for a starting column and returns
* blocks before/after it for each next call. This function assumes that
* the CF is sorted by name and exploits the name index.
*/
class IndexedSliceReader extends AbstractIterator<IColumn> implements IColumnIterator
{
private final ColumnFamily emptyColumnFamily;
private final List<IndexHelper.IndexInfo> indexes;
private final FileDataInput file;
private final ByteBuffer startColumn;
private final ByteBuffer finishColumn;
private final boolean reversed;
private BlockFetcher fetcher;
private Deque<IColumn> blockColumns = new ArrayDeque<IColumn>();
private AbstractType comparator;
public IndexedSliceReader(SSTableReader sstable, FileDataInput input, ByteBuffer startColumn, ByteBuffer finishColumn, boolean reversed)
{
this.file = input;
this.startColumn = startColumn;
this.finishColumn = finishColumn;
this.reversed = reversed;
comparator = sstable.metadata.comparator;
try
{
IndexHelper.skipBloomFilter(file);
indexes = IndexHelper.deserializeIndex(file);
emptyColumnFamily = ColumnFamily.serializer().deserializeFromSSTableNoColumns(ColumnFamily.create(sstable.metadata), file);
fetcher = indexes == null ? new SimpleBlockFetcher() : new IndexedBlockFetcher();
}
catch (IOException e)
{
throw new IOError(e);
}
}
public ColumnFamily getColumnFamily()
{
return emptyColumnFamily;
}
public DecoratedKey getKey()
{
throw new UnsupportedOperationException();
}
private boolean isColumnNeeded(IColumn column)
{
if (startColumn.remaining() == 0 && finishColumn.remaining() == 0)
return true;
else if (startColumn.remaining() == 0 && !reversed)
return comparator.compare(column.name(), finishColumn) <= 0;
else if (startColumn.remaining() == 0 && reversed)
return comparator.compare(column.name(), finishColumn) >= 0;
else if (finishColumn.remaining() == 0 && !reversed)
return comparator.compare(column.name(), startColumn) >= 0;
else if (finishColumn.remaining() == 0 && reversed)
return comparator.compare(column.name(), startColumn) <= 0;
else if (!reversed)
return comparator.compare(column.name(), startColumn) >= 0 && comparator.compare(column.name(), finishColumn) <= 0;
else // if reversed
return comparator.compare(column.name(), startColumn) <= 0 && comparator.compare(column.name(), finishColumn) >= 0;
}
protected IColumn computeNext()
{
while (true)
{
IColumn column = blockColumns.poll();
if (column != null && isColumnNeeded(column))
return column;
try
{
if (column == null && !fetcher.getNextBlock())
return endOfData();
}
catch (IOException e)
{
throw new RuntimeException(e);
}
}
}
public void close()
{
}
interface BlockFetcher
{
public boolean getNextBlock() throws IOException;
}
private class IndexedBlockFetcher implements BlockFetcher
{
private final FileMark mark;
private int curRangeIndex;
IndexedBlockFetcher() throws IOException
{
file.readInt(); // column count
this.mark = file.mark();
curRangeIndex = IndexHelper.indexFor(startColumn, indexes, comparator, reversed);
}
public boolean getNextBlock() throws IOException
{
if (curRangeIndex < 0 || curRangeIndex >= indexes.size())
return false;
/* seek to the correct offset to the data, and calculate the data size */
IndexHelper.IndexInfo curColPosition = indexes.get(curRangeIndex);
/* see if this read is really necessary. */
if (reversed)
{
if ((finishColumn.remaining() > 0 && comparator.compare(finishColumn, curColPosition.lastName) > 0) ||
(startColumn.remaining() > 0 && comparator.compare(startColumn, curColPosition.firstName) < 0))
return false;
}
else
{
if ((startColumn.remaining() > 0 && comparator.compare(startColumn, curColPosition.lastName) > 0) ||
(finishColumn.remaining() > 0 && comparator.compare(finishColumn, curColPosition.firstName) < 0))
return false;
}
boolean outOfBounds = false;
file.reset(mark);
long curOffset = file.skipBytes((int) curColPosition.offset);
assert curOffset == curColPosition.offset;
while (file.bytesPastMark(mark) < curColPosition.offset + curColPosition.width && !outOfBounds)
{
IColumn column = emptyColumnFamily.getColumnSerializer().deserialize(file);
if (reversed)
blockColumns.addFirst(column);
else
blockColumns.addLast(column);
/* see if we can stop seeking. */
if (!reversed && finishColumn.remaining() > 0)
outOfBounds = comparator.compare(column.name(), finishColumn) >= 0;
else if (reversed && startColumn.remaining() > 0)
outOfBounds = comparator.compare(column.name(), startColumn) >= 0;
}
if (reversed)
curRangeIndex--;
else
curRangeIndex++;
return true;
}
}
private class SimpleBlockFetcher implements BlockFetcher
{
private SimpleBlockFetcher() throws IOException
{
int columns = file.readInt();
for (int i = 0; i < columns; i++)
{
IColumn column = emptyColumnFamily.getColumnSerializer().deserialize(file);
if (reversed)
blockColumns.addFirst(column);
else
blockColumns.addLast(column);
/* see if we can stop seeking. */
boolean outOfBounds = false;
if (!reversed && finishColumn.remaining() > 0)
outOfBounds = comparator.compare(column.name(), finishColumn) >= 0;
else if (reversed && startColumn.remaining() > 0)
outOfBounds = comparator.compare(column.name(), startColumn) >= 0;
if (outOfBounds)
break;
}
}
public boolean getNextBlock() throws IOException
{
return false;
}
}
}