maedhroz commented on code in PR #2409: URL: https://github.com/apache/cassandra/pull/2409#discussion_r1245751023
########## src/java/org/apache/cassandra/index/sai/disk/v1/bbtree/NumericIndexWriter.java: ########## @@ -0,0 +1,179 @@ +/* + * 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.LinkedHashMap; +import java.util.List; +import java.util.Map; + +import com.google.common.annotations.VisibleForTesting; +import com.google.common.base.MoreObjects; + +import org.apache.cassandra.index.sai.IndexContext; +import org.apache.cassandra.index.sai.disk.format.IndexComponent; +import org.apache.cassandra.index.sai.disk.format.IndexDescriptor; +import org.apache.cassandra.index.sai.disk.v1.segment.SegmentMetadata; +import org.apache.lucene.store.IndexOutput; +import org.apache.lucene.util.packed.PackedInts; +import org.apache.lucene.util.packed.PackedLongValues; + +import static com.google.common.base.Preconditions.checkArgument; + +/** + * Specialized writer for point values, that builds them into a {@link BlockBalancedTreeWriter} with auxiliary + * posting lists on eligible tree levels. + * <p> + * Given a sorted input {@link IntersectingPointValues}, the flush process is optimised because we don't need to + * buffer all point values to sort them. + */ +public class NumericIndexWriter +{ + public static final int MAX_POINTS_IN_LEAF_NODE = BlockBalancedTreeWriter.DEFAULT_MAX_POINTS_IN_LEAF_NODE; + private static final int DEFAULT_POSTINGS_SIZE = 128; + + private final BlockBalancedTreeWriter writer; + private final IndexDescriptor indexDescriptor; + private final IndexContext indexContext; + private final int bytesPerValue; + + /** + * @param maxSegmentRowId maximum possible segment row ID, used to create `maxRows` for the balanced tree + */ + public NumericIndexWriter(IndexDescriptor indexDescriptor, + IndexContext indexContext, + int bytesPerValue, + long maxSegmentRowId) + { + this(indexDescriptor, indexContext, MAX_POINTS_IN_LEAF_NODE, bytesPerValue, maxSegmentRowId); + } + + @VisibleForTesting + public NumericIndexWriter(IndexDescriptor indexDescriptor, + IndexContext indexContext, + int maxPointsInLeafNode, + int bytesPerValue, + long maxSegmentRowId) + { + checkArgument(maxSegmentRowId >= 0, "[%s] maxSegmentRowId must be non-negative value, but got %s", indexContext.getIndexName(), maxSegmentRowId); + + this.indexDescriptor = indexDescriptor; + this.indexContext = indexContext; + this.bytesPerValue = bytesPerValue; + this.writer = new BlockBalancedTreeWriter(maxSegmentRowId + 1, bytesPerValue, maxPointsInLeafNode); + } + + @Override + public String toString() + { + return MoreObjects.toStringHelper(this) + .add("indexContext", indexContext) + .add("bytesPerValue", bytesPerValue) + .toString(); + } + + private static class LeafCallback implements BlockBalancedTreeWriter.Callback + { + final List<PackedLongValues> leafPostings = new ArrayList<>(DEFAULT_POSTINGS_SIZE); + + public int numLeaves() + { + return leafPostings.size(); + } + + @Override + public void writeLeafPostings(BlockBalancedTreeWriter.RowIDAndIndex[] leafPostings, int offset, int count) + { + PackedLongValues.Builder builder = PackedLongValues.monotonicBuilder(PackedInts.COMPACT); + + for (int i = offset; i < count; ++i) + { + builder.add(leafPostings[i].rowID); + } + this.leafPostings.add(builder.build()); + } + } + + /** + * Writes a balanced tree and posting lists from a {@link IntersectingPointValues}. + * + * @param values points to write + * + * @return metadata describing the location and size of this balanced tree in the overall SSTable balanced tree component file + */ + public SegmentMetadata.ComponentMetadataMap writeCompleteSegment(IntersectingPointValues values) throws IOException + { + long treePosition; + + SegmentMetadata.ComponentMetadataMap components = new SegmentMetadata.ComponentMetadataMap(); + + LeafCallback leafCallback = new LeafCallback(); + + try (IndexOutput treeOutput = indexDescriptor.openPerIndexOutput(IndexComponent.BALANCED_TREE, indexContext, true)) + { + // The SSTable balanced tree component file is opened in append mode, so our offset is the current file pointer. + long treeOffset = treeOutput.getFilePointer(); + + treePosition = writer.write(treeOutput, values, leafCallback); + + // If the treePosition is less than 0 then we didn't write any values out and the index is empty + if (treePosition < 0) + return components; + + long treeLength = treeOutput.getFilePointer() - treeOffset; + + Map<String, String> attributes = new LinkedHashMap<>(); + attributes.put("max_points_in_leaf_node", Integer.toString(writer.getMaxPointsInLeafNode())); + attributes.put("num_leaves", Integer.toString(leafCallback.numLeaves())); + attributes.put("num_points", Long.toString(writer.getValueCount())); + attributes.put("bytes_per_value", Long.toString(writer.getBytesPerValue())); + + components.put(IndexComponent.BALANCED_TREE, treePosition, treeOffset, treeLength, attributes); + } + + try (BlockBalancedTreeWalker reader = new BlockBalancedTreeWalker(indexDescriptor.createPerIndexFileHandle(IndexComponent.BALANCED_TREE, indexContext), treePosition); + IndexOutput postingsOutput = indexDescriptor.openPerIndexOutput(IndexComponent.POSTING_LISTS, indexContext, true)) + { + long postingsOffset = postingsOutput.getFilePointer(); + + BlockBalancedTreePostingsWriter postingsWriter = new BlockBalancedTreePostingsWriter(); + reader.traverse(postingsWriter); + + // The balanced tree postings writer already writes its own header & footer. + long postingsPosition = postingsWriter.finish(postingsOutput, leafCallback.leafPostings, indexContext); + + Map<String, String> attributes = new LinkedHashMap<>(); + attributes.put("num_leaf_postings", Integer.toString(postingsWriter.numLeafPostings)); + attributes.put("num_non_leaf_postings", Integer.toString(postingsWriter.numNonLeafPostings)); + + long postingsLength = postingsOutput.getFilePointer() - postingsOffset; + components.put(IndexComponent.POSTING_LISTS, postingsPosition, postingsOffset, postingsLength, attributes); + } + + return components; + } + + /** + * @return number of points added + */ + public long getPointCount() Review Comment: ```suggestion public long getValueCount() ``` ? -- This is an automated message from the Apache Git Service. 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