mike-tr-adamson commented on code in PR #2409: URL: https://github.com/apache/cassandra/pull/2409#discussion_r1229701253
########## src/java/org/apache/cassandra/index/sai/disk/v1/bbtree/BlockBalancedTreeWriter.java: ########## @@ -0,0 +1,766 @@ +/* + * 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.IOException; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.List; +import java.util.function.IntFunction; + +import com.google.common.base.MoreObjects; + +import org.apache.cassandra.index.sai.disk.io.RAMIndexOutput; +import org.apache.cassandra.index.sai.disk.v1.SAICodecUtils; +import org.apache.lucene.store.DataOutput; +import org.apache.lucene.store.GrowableByteArrayDataOutput; +import org.apache.lucene.store.IndexOutput; +import org.apache.lucene.util.ArrayUtil; +import org.apache.lucene.util.BytesRef; +import org.apache.lucene.util.FutureArrays; +import org.apache.lucene.util.IntroSorter; +import org.apache.lucene.util.Sorter; +import org.apache.lucene.util.bkd.MutablePointsReaderUtils; + +/** + * This is a specialisation of the lucene BKDWriter that only writes a single dimension + * balanced tree. + * <p> + * Recursively builds a block balanced tree to assign all incoming points to smaller + * and smaller rectangles (cells) until the number of points in a given + * rectangle is <= <code>maxPointsInLeafNode</code>. The tree is + * fully balanced, which means the leaf nodes will have between 50% and 100% of + * the requested <code>maxPointsInLeafNode</code>. Values that fall exactly + * on a cell boundary may be in either cell. + * + * <p> + * <b>NOTE</b>: This can write at most Integer.MAX_VALUE * <code>maxPointsInLeafNode</code> total points. + */ +public class BlockBalancedTreeWriter +{ + // Enable to check that values are added to the tree in correct order and within bounds + private static final boolean DEBUG = false; + + // Default maximum number of point in each leaf block + public static final int DEFAULT_MAX_POINTS_IN_LEAF_NODE = 1024; + + private final int bytesPerValue; + private final BytesRef scratchBytesRef1 = new BytesRef(); + private final int maxPointsInLeafNode; + private final byte[] minPackedValue; + private final byte[] maxPackedValue; + private long pointCount; + private final long maxDoc; + + public BlockBalancedTreeWriter(long maxDoc, int bytesPerValue, int maxPointsInLeafNode) + { + if (maxPointsInLeafNode <= 0) + throw new IllegalArgumentException("maxPointsInLeafNode must be > 0; got " + maxPointsInLeafNode); + if (maxPointsInLeafNode > ArrayUtil.MAX_ARRAY_LENGTH) + throw new IllegalArgumentException("maxPointsInLeafNode must be <= ArrayUtil.MAX_ARRAY_LENGTH (= " + + ArrayUtil.MAX_ARRAY_LENGTH + "); got " + maxPointsInLeafNode); + + this.maxPointsInLeafNode = maxPointsInLeafNode; + this.bytesPerValue = bytesPerValue; + this.maxDoc = maxDoc; + + minPackedValue = new byte[bytesPerValue]; + maxPackedValue = new byte[bytesPerValue]; + } + + public long getPointCount() + { + return pointCount; + } + + public int getBytesPerValue() + { + return bytesPerValue; + } + + public int getMaxPointsInLeafNode() + { + return maxPointsInLeafNode; + } + + /** + * Write the point values from a {@link IntersectingPointValues}. The points can be reordered before writing + * to disk and does not use transient disk for reordering. + */ Review Comment: I've copied from the `PostingsWriter` and added a visual representation of the layout. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
