/*
* 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.*;
import com.google.common.collect.AbstractIterator;
import com.google.common.collect.Ordering;
import com.google.common.util.concurrent.RateLimiter;
import org.apache.cassandra.db.DataRange;
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.dht.AbstractBounds;
import org.apache.cassandra.dht.AbstractBounds.Boundary;
import org.apache.cassandra.dht.Bounds;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.io.util.RandomAccessReader;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.Pair;
import static org.apache.cassandra.dht.AbstractBounds.isEmpty;
import static org.apache.cassandra.dht.AbstractBounds.maxLeft;
import static org.apache.cassandra.dht.AbstractBounds.minRight;
public class SSTableScanner implements ISSTableScanner
{
protected final RandomAccessReader dfile;
protected final RandomAccessReader ifile;
public final SSTableReader sstable;
private final Iterator<AbstractBounds<RowPosition>> rangeIterator;
private AbstractBounds<RowPosition> currentRange;
private final DataRange dataRange;
protected Iterator<OnDiskAtomIterator> iterator;
public static ISSTableScanner getScanner(SSTableReader sstable, DataRange dataRange, RateLimiter limiter)
{
return new SSTableScanner(sstable, dataRange, limiter);
}
public static ISSTableScanner getScanner(SSTableReader sstable, Collection<Range<Token>> tokenRanges, RateLimiter limiter)
{
// We want to avoid allocating a SSTableScanner if the range don't overlap the sstable (#5249)
List<Pair<Long, Long>> positions = sstable.getPositionsForRanges(tokenRanges);
if (positions.isEmpty())
return new EmptySSTableScanner(sstable.getFilename());
return new SSTableScanner(sstable, tokenRanges, limiter);
}
/**
* @param sstable SSTable to scan; must not be null
* @param dataRange a single range to scan; must not be null
* @param limiter background i/o RateLimiter; may be null
*/
private SSTableScanner(SSTableReader sstable, DataRange dataRange, RateLimiter limiter)
{
assert sstable != null;
this.dfile = limiter == null ? sstable.openDataReader() : sstable.openDataReader(limiter);
this.ifile = sstable.openIndexReader();
this.sstable = sstable;
this.dataRange = dataRange;
List<AbstractBounds<RowPosition>> boundsList = new ArrayList<>(2);
addRange(dataRange.keyRange(), boundsList);
this.rangeIterator = boundsList.iterator();
}
/**
* @param sstable SSTable to scan; must not be null
* @param tokenRanges A set of token ranges to scan
* @param limiter background i/o RateLimiter; may be null
*/
private SSTableScanner(SSTableReader sstable, Collection<Range<Token>> tokenRanges, RateLimiter limiter)
{
assert sstable != null;
this.dfile = limiter == null ? sstable.openDataReader() : sstable.openDataReader(limiter);
this.ifile = sstable.openIndexReader();
this.sstable = sstable;
this.dataRange = null;
List<AbstractBounds<RowPosition>> boundsList = new ArrayList<>(tokenRanges.size());
for (Range<Token> range : Range.normalize(tokenRanges))
addRange(range.toRowBounds(), boundsList);
this.rangeIterator = boundsList.iterator();
}
private void addRange(AbstractBounds<RowPosition> requested, List<AbstractBounds<RowPosition>> boundsList)
{
if (requested instanceof Range && ((Range)requested).isWrapAround())
{
if (requested.right.compareTo(sstable.first) >= 0)
{
// since we wrap, we must contain the whole sstable prior to stopKey()
Boundary<RowPosition> left = new Boundary<RowPosition>(sstable.first, true);
Boundary<RowPosition> right;
right = requested.rightBoundary();
right = minRight(right, sstable.last, true);
if (!isEmpty(left, right))
boundsList.add(AbstractBounds.bounds(left, right));
}
if (requested.left.compareTo(sstable.last) <= 0)
{
// since we wrap, we must contain the whole sstable after dataRange.startKey()
Boundary<RowPosition> right = new Boundary<RowPosition>(sstable.last, true);
Boundary<RowPosition> left;
left = requested.leftBoundary();
left = maxLeft(left, sstable.first, true);
if (!isEmpty(left, right))
boundsList.add(AbstractBounds.bounds(left, right));
}
}
else
{
assert requested.left.compareTo(requested.right) <= 0 || requested.right.isMinimum();
Boundary<RowPosition> left, right;
left = requested.leftBoundary();
right = requested.rightBoundary();
left = maxLeft(left, sstable.first, true);
// apparently isWrapAround() doesn't count Bounds that extend to the limit (min) as wrapping
right = requested.right.isMinimum() ? new Boundary<RowPosition>(sstable.last, true)
: minRight(right, sstable.last, true);
if (!isEmpty(left, right))
boundsList.add(AbstractBounds.bounds(left, right));
}
}
private void seekToCurrentRangeStart()
{
long indexPosition = sstable.getIndexScanPosition(currentRange.left);
ifile.seek(indexPosition);
try
{
while (!ifile.isEOF())
{
indexPosition = ifile.getFilePointer();
DecoratedKey indexDecoratedKey = sstable.partitioner.decorateKey(ByteBufferUtil.readWithShortLength(ifile));
if (indexDecoratedKey.compareTo(currentRange.left) > 0 || currentRange.contains(indexDecoratedKey))
{
// Found, just read the dataPosition and seek into index and data files
long dataPosition = ifile.readLong();
ifile.seek(indexPosition);
dfile.seek(dataPosition);
break;
}
else
{
RowIndexEntry.Serializer.skip(ifile);
}
}
}
catch (IOException e)
{
sstable.markSuspect();
throw new CorruptSSTableException(e, sstable.getFilename());
}
}
public void close() throws IOException
{
FileUtils.close(dfile, ifile);
}
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 = createIterator();
return iterator.hasNext();
}
public OnDiskAtomIterator next()
{
if (iterator == null)
iterator = createIterator();
return iterator.next();
}
public void remove()
{
throw new UnsupportedOperationException();
}
private Iterator<OnDiskAtomIterator> createIterator()
{
return new KeyScanningIterator();
}
protected class KeyScanningIterator extends AbstractIterator<OnDiskAtomIterator>
{
private DecoratedKey nextKey;
private RowIndexEntry nextEntry;
private DecoratedKey currentKey;
private RowIndexEntry currentEntry;
protected OnDiskAtomIterator computeNext()
{
try
{
if (nextEntry == null)
{
do
{
// we're starting the first range or we just passed the end of the previous range
if (!rangeIterator.hasNext())
return endOfData();
currentRange = rangeIterator.next();
seekToCurrentRangeStart();
if (ifile.isEOF())
return endOfData();
currentKey = sstable.partitioner.decorateKey(ByteBufferUtil.readWithShortLength(ifile));
currentEntry = sstable.metadata.comparator.rowIndexEntrySerializer().deserialize(ifile, sstable.descriptor.version);
} while (!currentRange.contains(currentKey));
}
else
{
// we're in the middle of a range
currentKey = nextKey;
currentEntry = nextEntry;
}
long readEnd;
if (ifile.isEOF())
{
nextEntry = null;
nextKey = null;
readEnd = dfile.length();
}
else
{
// we need the position of the start of the next key, regardless of whether it falls in the current range
nextKey = sstable.partitioner.decorateKey(ByteBufferUtil.readWithShortLength(ifile));
nextEntry = sstable.metadata.comparator.rowIndexEntrySerializer().deserialize(ifile, sstable.descriptor.version);
readEnd = nextEntry.position;
if (!currentRange.contains(nextKey))
{
nextKey = null;
nextEntry = null;
}
}
if (dataRange == null || dataRange.selectsFullRowFor(currentKey.getKey()))
{
dfile.seek(currentEntry.position);
ByteBufferUtil.readWithShortLength(dfile); // key
long dataSize = readEnd - dfile.getFilePointer();
return new SSTableIdentityIterator(sstable, dfile, currentKey, dataSize);
}
return new LazyColumnIterator(currentKey, new IColumnIteratorFactory()
{
public OnDiskAtomIterator create()
{
return dataRange.columnFilter(currentKey.getKey()).getSSTableColumnIterator(sstable, dfile, currentKey, currentEntry);
}
});
}
catch (IOException e)
{
sstable.markSuspect();
throw new CorruptSSTableException(e, sstable.getFilename());
}
}
}
@Override
public String toString()
{
return getClass().getSimpleName() + "(" +
"dfile=" + dfile +
" ifile=" + ifile +
" sstable=" + sstable +
")";
}
public static class EmptySSTableScanner implements ISSTableScanner
{
private final String filename;
public EmptySSTableScanner(String filename)
{
this.filename = filename;
}
public long getLengthInBytes()
{
return 0;
}
public long getCurrentPosition()
{
return 0;
}
public String getBackingFiles()
{
return filename;
}
public boolean hasNext()
{
return false;
}
public OnDiskAtomIterator next()
{
return null;
}
public void close() throws IOException { }
public void remove() { }
}
}