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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.index.sai.disk.v1.bbtree;
import java.io.Closeable;
import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.concurrent.TimeUnit;
import com.google.common.base.Stopwatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.exceptions.QueryCancelledException;
import org.apache.cassandra.index.sai.QueryContext;
import org.apache.cassandra.index.sai.utils.IndexIdentifier;
import org.apache.cassandra.index.sai.disk.io.IndexFileUtils;
import org.apache.cassandra.index.sai.disk.io.SeekingRandomAccessInput;
import org.apache.cassandra.index.sai.disk.v1.postings.FilteringPostingList;
import org.apache.cassandra.index.sai.disk.v1.postings.MergePostingList;
import org.apache.cassandra.index.sai.disk.v1.postings.PostingsReader;
import org.apache.cassandra.index.sai.metrics.QueryEventListener;
import org.apache.cassandra.index.sai.postings.PeekablePostingList;
import org.apache.cassandra.index.sai.postings.PostingList;
import org.apache.cassandra.io.util.FileHandle;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.utils.ByteArrayUtil;
import org.apache.cassandra.utils.Throwables;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.PointValues.Relation;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.util.FixedBitSet;
import org.apache.lucene.util.LongValues;
import org.apache.lucene.util.packed.DirectReader;
import org.apache.lucene.util.packed.DirectWriter;
/**
* Handles intersection of a point or point range with a block balanced tree previously written with
* {@link BlockBalancedTreeWriter}.
*/
public class BlockBalancedTreeReader extends BlockBalancedTreeWalker implements Closeable
{
private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
private static final Comparator COMPARATOR = Comparator.comparingLong(PeekablePostingList::peek);
private final IndexIdentifier indexIdentifier;
private final FileHandle postingsFile;
private final BlockBalancedTreePostingsIndex postingsIndex;
private final int leafOrderMapBitsRequired;
/**
* Performs a blocking read.
*/
public BlockBalancedTreeReader(IndexIdentifier indexIdentifier,
FileHandle treeIndexFile,
long treeIndexRoot,
FileHandle postingsFile,
long treePostingsRoot) throws IOException
{
super(treeIndexFile, treeIndexRoot);
this.indexIdentifier = indexIdentifier;
this.postingsFile = postingsFile;
this.postingsIndex = new BlockBalancedTreePostingsIndex(postingsFile, treePostingsRoot);
leafOrderMapBitsRequired = DirectWriter.unsignedBitsRequired(maxValuesInLeafNode - 1);
}
public int getBytesPerValue()
{
return bytesPerValue;
}
public long getPointCount()
{
return valueCount;
}
@Override
public void close()
{
super.close();
FileUtils.closeQuietly(postingsFile);
}
public PostingList intersect(IntersectVisitor visitor, QueryEventListener.BalancedTreeEventListener listener, QueryContext context)
{
Relation relation = visitor.compare(minPackedValue, maxPackedValue);
if (relation == Relation.CELL_OUTSIDE_QUERY)
{
listener.onIntersectionEarlyExit();
return null;
}
listener.onSegmentHit();
IndexInput treeInput = IndexFileUtils.instance.openInput(treeIndexFile);
IndexInput postingsInput = IndexFileUtils.instance.openInput(postingsFile);
IndexInput postingsSummaryInput = IndexFileUtils.instance.openInput(postingsFile);
Intersection intersection = relation == Relation.CELL_INSIDE_QUERY
? new Intersection(treeInput, postingsInput, postingsSummaryInput, listener, context)
: new FilteringIntersection(treeInput, postingsInput, postingsSummaryInput, visitor, listener, context);
return intersection.execute();
}
/**
* Synchronous intersection of a point or point range with a block balanced tree previously written
* with {@link BlockBalancedTreeWriter}.
*/
private class Intersection
{
private final Stopwatch queryExecutionTimer = Stopwatch.createStarted();
final QueryContext context;
final TraversalState state;
final IndexInput treeInput;
final IndexInput postingsInput;
final IndexInput postingsSummaryInput;
final QueryEventListener.BalancedTreeEventListener listener;
final PriorityQueue postingLists;
Intersection(IndexInput treeInput, IndexInput postingsInput, IndexInput postingsSummaryInput,
QueryEventListener.BalancedTreeEventListener listener, QueryContext context)
{
this.state = newTraversalState();
this.treeInput = treeInput;
this.postingsInput = postingsInput;
this.postingsSummaryInput = postingsSummaryInput;
this.listener = listener;
this.context = context;
postingLists = new PriorityQueue<>(numLeaves, COMPARATOR);
}
public PostingList execute()
{
try
{
executeInternal();
FileUtils.closeQuietly(treeInput);
return mergePostings();
}
catch (Throwable t)
{
if (!(t instanceof QueryCancelledException))
logger.error(indexIdentifier.logMessage("Balanced tree intersection failed on {}"), treeIndexFile.path(), t);
closeOnException();
throw Throwables.cleaned(t);
}
}
protected void executeInternal() throws IOException
{
collectPostingLists();
}
protected void closeOnException()
{
FileUtils.closeQuietly(treeInput);
FileUtils.closeQuietly(postingsInput);
FileUtils.closeQuietly(postingsSummaryInput);
}
protected PostingList mergePostings()
{
final long elapsedMicros = queryExecutionTimer.stop().elapsed(TimeUnit.MICROSECONDS);
listener.onIntersectionComplete(elapsedMicros, TimeUnit.MICROSECONDS);
listener.postingListsHit(postingLists.size());
if (postingLists.isEmpty())
{
FileUtils.closeQuietly(postingsInput);
FileUtils.closeQuietly(postingsSummaryInput);
return null;
}
else
{
if (logger.isTraceEnabled())
logger.trace(indexIdentifier.logMessage("[{}] Intersection completed in {} microseconds. {} leaf and internal posting lists hit."),
treeIndexFile.path(), elapsedMicros, postingLists.size());
return MergePostingList.merge(postingLists, () -> FileUtils.close(postingsInput, postingsSummaryInput));
}
}
private void collectPostingLists() throws IOException
{
context.checkpoint();
// This will return true if the node is a child leaf that has postings or if there is postings for the
// entire subtree under a leaf
if (postingsIndex.exists(state.nodeID))
{
postingLists.add(initPostingReader(postingsIndex.getPostingsFilePointer(state.nodeID)));
return;
}
if (state.atLeafNode())
throw new CorruptIndexException(indexIdentifier.logMessage(String.format("Leaf node %s does not have balanced tree postings.", state.nodeID)), "");
// Recurse on left subtree:
state.pushLeft();
collectPostingLists();
state.pop();
// Recurse on right subtree:
state.pushRight();
collectPostingLists();
state.pop();
}
private PeekablePostingList initPostingReader(long offset) throws IOException
{
final PostingsReader.BlocksSummary summary = new PostingsReader.BlocksSummary(postingsSummaryInput, offset);
return PeekablePostingList.makePeekable(new PostingsReader(postingsInput, summary, listener.postingListEventListener()));
}
}
private class FilteringIntersection extends Intersection
{
private final IntersectVisitor visitor;
private final byte[] packedValue;
private final short[] origIndex;
FilteringIntersection(IndexInput treeInput, IndexInput postingsInput, IndexInput postingsSummaryInput,
IntersectVisitor visitor, QueryEventListener.BalancedTreeEventListener listener, QueryContext context)
{
super(treeInput, postingsInput, postingsSummaryInput, listener, context);
this.visitor = visitor;
this.packedValue = new byte[bytesPerValue];
this.origIndex = new short[maxValuesInLeafNode];
}
@Override
public void executeInternal() throws IOException
{
collectPostingLists(minPackedValue, maxPackedValue);
}
private void collectPostingLists(byte[] minPackedValue, byte[] maxPackedValue) throws IOException
{
context.checkpoint();
final Relation r = visitor.compare(minPackedValue, maxPackedValue);
// This value range is fully outside the query shape: stop recursing
if (r == Relation.CELL_OUTSIDE_QUERY)
return;
if (r == Relation.CELL_INSIDE_QUERY)
{
// This value range is fully inside the query shape: recursively add all points from this node without filtering
super.collectPostingLists();
return;
}
if (state.atLeafNode())
{
if (state.nodeExists())
filterLeaf();
return;
}
visitNode(minPackedValue, maxPackedValue);
}
private void filterLeaf() throws IOException
{
treeInput.seek(state.getLeafBlockFP());
int count = treeInput.readVInt();
int orderMapLength = treeInput.readVInt();
long orderMapPointer = treeInput.getFilePointer();
SeekingRandomAccessInput randomAccessInput = new SeekingRandomAccessInput(treeInput);
LongValues leafOrderMapReader = DirectReader.getInstance(randomAccessInput, leafOrderMapBitsRequired, orderMapPointer);
for (int index = 0; index < count; index++)
{
origIndex[index] = (short) Math.toIntExact(leafOrderMapReader.get(index));
}
// seek beyond the ordermap
treeInput.seek(orderMapPointer + orderMapLength);
FixedBitSet fixedBitSet = buildPostingsFilter(treeInput, count, visitor, origIndex);
if (postingsIndex.exists(state.nodeID) && fixedBitSet.cardinality() > 0)
{
long pointer = postingsIndex.getPostingsFilePointer(state.nodeID);
postingLists.add(initFilteringPostingReader(pointer, fixedBitSet));
}
}
void visitNode(byte[] minPackedValue, byte[] maxPackedValue) throws IOException
{
assert !state.atLeafNode() : "Cannot recurse down tree because nodeID " + state.nodeID + " is a leaf node";
byte[] splitValue = state.getSplitValue();
if (BlockBalancedTreeWriter.DEBUG)
{
// make sure cellMin <= splitValue <= cellMax:
assert ByteArrayUtil.compareUnsigned(minPackedValue, 0, splitValue, 0, bytesPerValue) <= 0 :"bytesPerValue=" + bytesPerValue;
assert ByteArrayUtil.compareUnsigned(maxPackedValue, 0, splitValue, 0, bytesPerValue) >= 0 : "bytesPerValue=" + bytesPerValue;
}
// Recurse on left subtree:
state.pushLeft();
collectPostingLists(minPackedValue, splitValue);
state.pop();
// Recurse on right subtree:
state.pushRight();
collectPostingLists(splitValue, maxPackedValue);
state.pop();
}
private PeekablePostingList initFilteringPostingReader(long offset, FixedBitSet filter) throws IOException
{
final PostingsReader.BlocksSummary summary = new PostingsReader.BlocksSummary(postingsSummaryInput, offset);
PostingsReader postingsReader = new PostingsReader(postingsInput, summary, listener.postingListEventListener());
return PeekablePostingList.makePeekable(new FilteringPostingList(filter, postingsReader));
}
private FixedBitSet buildPostingsFilter(IndexInput in, int count, IntersectVisitor visitor, short[] origIndex) throws IOException
{
int commonPrefixLength = readCommonPrefixLength(in);
return commonPrefixLength == bytesPerValue ? buildPostingsFilterForSingleValueLeaf(count, visitor, origIndex)
: buildPostingsFilterForMultiValueLeaf(commonPrefixLength, in, count, visitor, origIndex);
}
private FixedBitSet buildPostingsFilterForMultiValueLeaf(int commonPrefixLength,
IndexInput in,
int count,
IntersectVisitor visitor,
short[] origIndex) throws IOException
{
// the byte at `compressedByteOffset` is compressed using run-length compression,
// other suffix bytes are stored verbatim
int compressedByteOffset = commonPrefixLength;
commonPrefixLength++;
int i;
FixedBitSet fixedBitSet = new FixedBitSet(maxValuesInLeafNode);
for (i = 0; i < count; )
{
packedValue[compressedByteOffset] = in.readByte();
final int runLen = Byte.toUnsignedInt(in.readByte());
for (int j = 0; j < runLen; ++j)
{
in.readBytes(packedValue, commonPrefixLength, bytesPerValue - commonPrefixLength);
final int rowIDIndex = origIndex[i + j];
if (visitor.contains(packedValue))
fixedBitSet.set(rowIDIndex);
}
i += runLen;
}
if (i != count)
throw new CorruptIndexException(String.format("Expected %d sub-blocks but read %d.", count, i), in);
return fixedBitSet;
}
private FixedBitSet buildPostingsFilterForSingleValueLeaf(int count, IntersectVisitor visitor, final short[] origIndex)
{
FixedBitSet fixedBitSet = new FixedBitSet(maxValuesInLeafNode);
// All the values in the leaf are the same, so we only
// need to visit once then set the bits for the relevant indexes
if (visitor.contains(packedValue))
{
for (int i = 0; i < count; ++i)
fixedBitSet.set(origIndex[i]);
}
return fixedBitSet;
}
private int readCommonPrefixLength(IndexInput in) throws IOException
{
int prefixLength = in.readVInt();
if (prefixLength > 0)
in.readBytes(packedValue, 0, prefixLength);
return prefixLength;
}
}
/**
* We recurse the balanced tree, using a provided instance of this to guide the recursion.
*/
public interface IntersectVisitor
{
/**
* Called for all values in a leaf cell that crosses the query. The consumer should scrutinize the packedValue
* to decide whether to accept it. Values are visited in increasing order, and in the case of ties,
* in increasing order by segment row ID.
*/
boolean contains(byte[] packedValue);
/**
* Called for non-leaf cells to test how the cell relates to the query, to
* determine how to further recurse down the tree.
*/
Relation compare(byte[] minPackedValue, byte[] maxPackedValue);
}
}