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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.Closeable;
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.cassandra.db.BufferClusteringBound;
import org.apache.cassandra.db.ClusteringBound;
import org.apache.cassandra.db.Columns;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.db.DeletionTime;
import org.apache.cassandra.db.RegularAndStaticColumns;
import org.apache.cassandra.db.Slice;
import org.apache.cassandra.db.Slices;
import org.apache.cassandra.db.UnfilteredDeserializer;
import org.apache.cassandra.db.UnfilteredValidation;
import org.apache.cassandra.db.filter.ColumnFilter;
import org.apache.cassandra.db.rows.DeserializationHelper;
import org.apache.cassandra.db.rows.EncodingStats;
import org.apache.cassandra.db.rows.RangeTombstoneBoundMarker;
import org.apache.cassandra.db.rows.RangeTombstoneMarker;
import org.apache.cassandra.db.rows.Row;
import org.apache.cassandra.db.rows.Rows;
import org.apache.cassandra.db.rows.Unfiltered;
import org.apache.cassandra.db.rows.UnfilteredRowIterator;
import org.apache.cassandra.db.rows.UnfilteredSerializer;
import org.apache.cassandra.io.sstable.format.SSTableReader;
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.schema.TableMetadata;
import org.apache.cassandra.utils.ByteBufferUtil;
import static org.apache.cassandra.utils.vint.VIntCoding.VIntOutOfRangeException;
public abstract class AbstractSSTableIterator implements UnfilteredRowIterator
{
protected final SSTableReader sstable;
// We could use sstable.metadata(), but that can change during execution so it's good hygiene to grab an immutable instance
protected final TableMetadata metadata;
protected final DecoratedKey key;
protected final DeletionTime partitionLevelDeletion;
protected final ColumnFilter columns;
protected final DeserializationHelper helper;
protected final Row staticRow;
protected final Reader reader;
protected final FileHandle ifile;
private boolean isClosed;
protected final Slices slices;
@SuppressWarnings("resource") // We need this because the analysis is not able to determine that we do close
// file on every path where we created it.
protected AbstractSSTableIterator(SSTableReader sstable,
FileDataInput file,
DecoratedKey key,
RIE indexEntry,
Slices slices,
ColumnFilter columnFilter,
FileHandle ifile)
{
this.sstable = sstable;
this.metadata = sstable.metadata();
this.ifile = ifile;
this.key = key;
this.columns = columnFilter;
this.slices = slices;
this.helper = new DeserializationHelper(metadata, sstable.descriptor.version.correspondingMessagingVersion(), DeserializationHelper.Flag.LOCAL, columnFilter);
if (indexEntry == null)
{
this.partitionLevelDeletion = DeletionTime.LIVE;
this.reader = null;
this.staticRow = Rows.EMPTY_STATIC_ROW;
}
else
{
boolean shouldCloseFile = file == null;
try
{
// We seek to the beginning to the partition if either:
// - the partition is not indexed; we then have a single block to read anyway
// (and we need to read the partition deletion time).
// - we're querying static columns.
boolean needSeekAtPartitionStart = !indexEntry.isIndexed() || !columns.fetchedColumns().statics.isEmpty();
if (needSeekAtPartitionStart)
{
// Not indexed (or is reading static), set to the beginning of the partition and read partition level deletion there
if (file == null)
file = sstable.getFileDataInput(indexEntry.position);
else
file.seek(indexEntry.position);
ByteBufferUtil.skipShortLength(file); // Skip partition key
this.partitionLevelDeletion = DeletionTime.getSerializer(sstable.descriptor.version).deserialize(file);
// Note that this needs to be called after file != null and after the partitionDeletion has been set, but before readStaticRow
// (since it uses it) so we can't move that up (but we'll be able to simplify as soon as we drop support for the old file format).
this.reader = createReader(indexEntry, file, shouldCloseFile);
this.staticRow = readStaticRow(sstable, file, helper, columns.fetchedColumns().statics);
}
else
{
this.partitionLevelDeletion = indexEntry.deletionTime();
this.staticRow = Rows.EMPTY_STATIC_ROW;
this.reader = createReader(indexEntry, file, shouldCloseFile);
}
if (!partitionLevelDeletion.validate())
UnfilteredValidation.handleInvalid(metadata(), key, sstable, "partitionLevelDeletion="+partitionLevelDeletion.toString());
if (reader != null && !slices.isEmpty())
reader.setForSlice(nextSlice());
if (reader == null && file != null && shouldCloseFile)
file.close();
}
catch (IOException e)
{
sstable.markSuspect();
String filePath = file.getPath();
if (shouldCloseFile)
{
try
{
file.close();
}
catch (IOException suppressed)
{
e.addSuppressed(suppressed);
}
}
throw new CorruptSSTableException(e, filePath);
}
}
}
private Slice nextSlice()
{
return slices.get(nextSliceIndex());
}
/**
* Returns the index of the next slice to process.
* @return the index of the next slice to process
*/
protected abstract int nextSliceIndex();
/**
* Checks if there are more slice to process.
* @return {@code true} if there are more slice to process, {@code false} otherwise.
*/
protected abstract boolean hasMoreSlices();
private static Row readStaticRow(SSTableReader sstable,
FileDataInput file,
DeserializationHelper helper,
Columns statics) throws IOException
{
if (!sstable.header.hasStatic())
return Rows.EMPTY_STATIC_ROW;
if (statics.isEmpty())
{
UnfilteredSerializer.serializer.skipStaticRow(file, sstable.header, helper);
return Rows.EMPTY_STATIC_ROW;
}
else
{
return UnfilteredSerializer.serializer.deserializeStaticRow(file, sstable.header, helper);
}
}
protected abstract Reader createReaderInternal(RIE indexEntry, FileDataInput file, boolean shouldCloseFile, Version version);
private Reader createReader(RIE indexEntry, FileDataInput file, boolean shouldCloseFile)
{
return slices.isEmpty() ? new NoRowsReader(file, shouldCloseFile)
: createReaderInternal(indexEntry, file, shouldCloseFile, sstable.descriptor.version);
};
public TableMetadata metadata()
{
return metadata;
}
public RegularAndStaticColumns columns()
{
return columns.fetchedColumns();
}
public DecoratedKey partitionKey()
{
return key;
}
public DeletionTime partitionLevelDeletion()
{
return partitionLevelDeletion;
}
public Row staticRow()
{
return staticRow;
}
public EncodingStats stats()
{
return sstable.stats();
}
public boolean hasNext()
{
while (true)
{
if (reader == null)
return false;
if (reader.hasNext())
return true;
if (!hasMoreSlices())
return false;
slice(nextSlice());
}
}
public Unfiltered next()
{
assert reader != null;
return reader.next();
}
private void slice(Slice slice)
{
try
{
if (reader != null)
reader.setForSlice(slice);
}
catch (IOException e)
{
try
{
closeInternal();
}
catch (IOException suppressed)
{
e.addSuppressed(suppressed);
}
sstable.markSuspect();
throw new CorruptSSTableException(e, reader.toString());
}
}
public void remove()
{
throw new UnsupportedOperationException();
}
private void closeInternal() throws IOException
{
// It's important to make closing idempotent since it would bad to double-close 'file' as its a RandomAccessReader
// and its close is not idemptotent in the case where we recycle it.
if (isClosed)
return;
if (reader != null)
reader.close();
isClosed = true;
}
public void close()
{
try
{
closeInternal();
}
catch (IOException e)
{
sstable.markSuspect();
throw new CorruptSSTableException(e, reader.toString());
}
}
public interface Reader extends Iterator, Closeable {
void setForSlice(Slice slice) throws IOException;
void seekToPosition(long columnOffset) throws IOException;
}
public abstract class AbstractReader implements Reader
{
private final boolean shouldCloseFile;
public FileDataInput file;
public UnfilteredDeserializer deserializer;
// Records the currently open range tombstone (if any)
public DeletionTime openMarker;
protected AbstractReader(FileDataInput file, boolean shouldCloseFile)
{
this.file = file;
this.shouldCloseFile = shouldCloseFile;
if (file != null)
createDeserializer();
}
private void createDeserializer()
{
assert file != null && deserializer == null;
deserializer = UnfilteredDeserializer.create(metadata, file, sstable.header, helper);
}
public void seekToPosition(long position) throws IOException
{
// This may be the first time we're actually looking into the file
if (file == null)
{
file = sstable.getFileDataInput(position);
createDeserializer();
}
else
{
file.seek(position);
deserializer.clearState();
}
}
protected void updateOpenMarker(RangeTombstoneMarker marker)
{
// Note that we always read index blocks in forward order so this method is always called in forward order
openMarker = marker.isOpen(false) ? marker.openDeletionTime(false) : null;
}
public boolean hasNext()
{
try
{
return hasNextInternal();
}
catch (IOException | IndexOutOfBoundsException | VIntOutOfRangeException e)
{
try
{
closeInternal();
}
catch (IOException suppressed)
{
e.addSuppressed(suppressed);
}
sstable.markSuspect();
throw new CorruptSSTableException(e, toString());
}
}
public Unfiltered next()
{
try
{
return nextInternal();
}
catch (IOException e)
{
try
{
closeInternal();
}
catch (IOException suppressed)
{
e.addSuppressed(suppressed);
}
sstable.markSuspect();
throw new CorruptSSTableException(e, toString());
}
}
// Set the reader so its hasNext/next methods return values within the provided slice
public abstract void setForSlice(Slice slice) throws IOException;
protected abstract boolean hasNextInternal() throws IOException;
protected abstract Unfiltered nextInternal() throws IOException;
@Override
public void close() throws IOException
{
if (shouldCloseFile && file != null)
file.close();
}
@Override
public String toString()
{
return file != null ? file.toString() : "null";
}
}
protected class ForwardReader extends AbstractReader
{
// The start of the current slice. This will be null as soon as we know we've passed that bound.
protected ClusteringBound start;
// The end of the current slice. Will never be null.
protected ClusteringBound end = BufferClusteringBound.TOP;
protected Unfiltered next; // the next element to return: this is computed by hasNextInternal().
protected boolean sliceDone; // set to true once we know we have no more result for the slice. This is in particular
// used by the indexed reader when we know we can't have results based on the index.
public ForwardReader(FileDataInput file, boolean shouldCloseFile)
{
super(file, shouldCloseFile);
}
public void setForSlice(Slice slice) throws IOException
{
start = slice.start().isBottom() ? null : slice.start();
end = slice.end();
sliceDone = false;
next = null;
}
// Skip all data that comes before the currently set slice.
// Return what should be returned at the end of this, or null if nothing should.
private Unfiltered handlePreSliceData() throws IOException
{
assert deserializer != null;
// Note that the following comparison is not strict. The reason is that the only cases
// where it can be == is if the "next" is a RT start marker (either a '[' of a ')[' boundary),
// and if we had a strict inequality and an open RT marker before this, we would issue
// the open marker first, and then return then next later, which would send in the
// stream both '[' (or '(') and then ')[' for the same clustering value, which is wrong.
// By using a non-strict inequality, we avoid that problem (if we do get ')[' for the same
// clustering value than the slice, we'll simply record it in 'openMarker').
while (deserializer.hasNext() && deserializer.compareNextTo(start) <= 0)
{
if (deserializer.nextIsRow())
deserializer.skipNext();
else
updateOpenMarker((RangeTombstoneMarker)deserializer.readNext());
}
ClusteringBound sliceStart = start;
start = null;
// We've reached the beginning of our queried slice. If we have an open marker
// we should return that first.
if (openMarker != null)
return new RangeTombstoneBoundMarker(sliceStart, openMarker);
return null;
}
// Compute the next element to return, assuming we're in the middle to the slice
// and the next element is either in the slice, or just after it. Returns null
// if we're done with the slice.
protected Unfiltered computeNext() throws IOException
{
assert deserializer != null;
while (true)
{
// We use a same reasoning as in handlePreSliceData regarding the strictness of the inequality below.
// We want to exclude deserialized unfiltered equal to end, because 1) we won't miss any rows since those
// woudn't be equal to a slice bound and 2) a end bound can be equal to a start bound
// (EXCL_END(x) == INCL_START(x) for instance) and in that case we don't want to return start bound because
// it's fundamentally excluded. And if the bound is a end (for a range tombstone), it means it's exactly
// our slice end, but in that case we will properly close the range tombstone anyway as part of our "close
// an open marker" code in hasNextInterna
if (!deserializer.hasNext() || deserializer.compareNextTo(end) >= 0)
return null;
Unfiltered next = deserializer.readNext();
UnfilteredValidation.maybeValidateUnfiltered(next, metadata(), key, sstable);
// We may get empty row for the same reason expressed on UnfilteredSerializer.deserializeOne.
if (next.isEmpty())
continue;
if (next.kind() == Unfiltered.Kind.RANGE_TOMBSTONE_MARKER)
updateOpenMarker((RangeTombstoneMarker) next);
return next;
}
}
protected boolean hasNextInternal() throws IOException
{
if (next != null)
return true;
if (sliceDone)
return false;
if (start != null)
{
Unfiltered unfiltered = handlePreSliceData();
if (unfiltered != null)
{
next = unfiltered;
return true;
}
}
next = computeNext();
if (next != null)
return true;
// for current slice, no data read from deserialization
sliceDone = true;
// If we have an open marker, we should not close it, there could be more slices
if (openMarker != null)
{
next = new RangeTombstoneBoundMarker(end, openMarker);
return true;
}
return false;
}
protected Unfiltered nextInternal() throws IOException
{
if (!hasNextInternal())
throw new NoSuchElementException();
Unfiltered toReturn = next;
next = null;
return toReturn;
}
}
// Reader for when we have Slices.NONE but need to read static row or partition level deletion
private class NoRowsReader extends AbstractReader
{
private NoRowsReader(FileDataInput file, boolean shouldCloseFile)
{
super(file, shouldCloseFile);
}
@Override
public void setForSlice(Slice slice)
{
// no-op
}
@Override
public boolean hasNextInternal()
{
return false;
}
@Override
protected Unfiltered nextInternal() throws IOException
{
throw new NoSuchElementException();
}
}
}
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