/*
* 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;
import java.io.IOException;
import java.util.Arrays;
import java.util.Iterator;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.db.RowIndexEntry;
import org.apache.cassandra.db.RowPosition;
import org.apache.cassandra.db.columniterator.IColumnIteratorFactory;
import org.apache.cassandra.db.columniterator.LazyColumnIterator;
import org.apache.cassandra.db.columniterator.OnDiskAtomIterator;
import org.apache.cassandra.db.compaction.ICompactionScanner;
import org.apache.cassandra.db.filter.QueryFilter;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.io.util.RandomAccessReader;
import org.apache.cassandra.utils.ByteBufferUtil;
public class SSTableScanner implements ICompactionScanner
{
protected final RandomAccessReader dfile;
protected final RandomAccessReader ifile;
public final SSTableReader sstable;
private OnDiskAtomIterator row;
protected boolean exhausted = false;
protected Iterator<OnDiskAtomIterator> iterator;
private final QueryFilter filter;
/**
* @param sstable SSTable to scan.
*/
SSTableScanner(SSTableReader sstable, boolean skipCache)
{
this.dfile = sstable.openDataReader(skipCache);
this.ifile = sstable.openIndexReader(skipCache);
this.sstable = sstable;
this.filter = null;
}
/**
* @param sstable SSTable to scan.
* @param filter filter to use when scanning the columns
*/
SSTableScanner(SSTableReader sstable, QueryFilter filter)
{
this.dfile = sstable.openDataReader(false);
this.ifile = sstable.openIndexReader(false);
this.sstable = sstable;
this.filter = filter;
}
public void close() throws IOException
{
FileUtils.close(dfile, ifile);
}
public void seekTo(RowPosition seekKey)
{
try
{
long indexPosition = sstable.getIndexScanPosition(seekKey);
// -1 means the key is before everything in the sstable. So just start from the beginning.
if (indexPosition == -1)
indexPosition = 0;
ifile.seek(indexPosition);
while (!ifile.isEOF())
{
long startPosition = ifile.getFilePointer();
DecoratedKey indexDecoratedKey = sstable.decodeKey(ByteBufferUtil.readWithShortLength(ifile));
int comparison = indexDecoratedKey.compareTo(seekKey);
if (comparison >= 0)
{
// Found, just read the dataPosition and seek into index and data files
long dataPosition = ifile.readLong();
ifile.seek(startPosition);
dfile.seek(dataPosition);
row = null;
return;
}
else
{
RowIndexEntry.serializer.skip(ifile, sstable.descriptor.version);
}
}
exhausted = true;
}
catch (IOException e)
{
sstable.markSuspect();
throw new CorruptSSTableException(e, ifile.getPath());
}
}
public long getLengthInBytes()
{
return dfile.length();
}
public long getCurrentPosition()
{
return dfile.getFilePointer();
}
public String getBackingFiles()
{
return sstable.toString();
}
public boolean hasNext()
{
if (iterator == null)
iterator = exhausted ? Arrays.asList(new OnDiskAtomIterator[0]).iterator() : createIterator();
return iterator.hasNext();
}
public OnDiskAtomIterator next()
{
if (iterator == null)
iterator = exhausted ? Arrays.asList(new OnDiskAtomIterator[0]).iterator() : createIterator();
return iterator.next();
}
public void remove()
{
throw new UnsupportedOperationException();
}
private Iterator<OnDiskAtomIterator> createIterator()
{
return filter == null ? new KeyScanningIterator() : new FilteredKeyScanningIterator();
}
protected class KeyScanningIterator implements Iterator<OnDiskAtomIterator>
{
protected long finishedAt;
public boolean hasNext()
{
if (row == null)
return !dfile.isEOF();
return finishedAt < dfile.length();
}
public OnDiskAtomIterator next()
{
try
{
if (row != null)
dfile.seek(finishedAt);
assert !dfile.isEOF();
// Read data header
DecoratedKey key = sstable.decodeKey(ByteBufferUtil.readWithShortLength(dfile));
long dataSize = SSTableReader.readRowSize(dfile, sstable.descriptor);
long dataStart = dfile.getFilePointer();
finishedAt = dataStart + dataSize;
row = new SSTableIdentityIterator(sstable, dfile, key, dataStart, dataSize);
return row;
}
catch (IOException e)
{
sstable.markSuspect();
throw new CorruptSSTableException(e, dfile.getPath());
}
}
public void remove()
{
throw new UnsupportedOperationException();
}
@Override
public String toString()
{
return getClass().getSimpleName() + "(" + "finishedAt:" + finishedAt + ")";
}
}
protected class FilteredKeyScanningIterator implements Iterator<OnDiskAtomIterator>
{
protected DecoratedKey nextKey;
protected RowIndexEntry nextEntry;
public boolean hasNext()
{
if (row == null)
return !ifile.isEOF();
return nextKey != null;
}
public OnDiskAtomIterator next()
{
try
{
final DecoratedKey currentKey;
final RowIndexEntry currentEntry;
if (row == null)
{
currentKey = sstable.decodeKey(ByteBufferUtil.readWithShortLength(ifile));
currentEntry = RowIndexEntry.serializer.deserialize(ifile, sstable.descriptor.version);
}
else
{
currentKey = nextKey;
currentEntry = nextEntry;
}
if (ifile.isEOF())
{
nextKey = null;
nextEntry = null;
}
else
{
nextKey = sstable.decodeKey(ByteBufferUtil.readWithShortLength(ifile));
nextEntry = RowIndexEntry.serializer.deserialize(ifile, sstable.descriptor.version);
}
assert !dfile.isEOF();
return row = new LazyColumnIterator(currentKey, new IColumnIteratorFactory()
{
public OnDiskAtomIterator create()
{
return filter.getSSTableColumnIterator(sstable, dfile, currentKey, currentEntry);
}
});
}
catch (IOException e)
{
sstable.markSuspect();
throw new CorruptSSTableException(e, ifile.getPath());
}
}
public void remove()
{
throw new UnsupportedOperationException();
}
}
@Override
public String toString()
{
return getClass().getSimpleName() + "(" +
"dfile=" + dfile +
" ifile=" + ifile +
" sstable=" + sstable +
" exhausted=" + exhausted +
")";
}
}