shubhamvishu commented on code in PR #13260: URL: https://github.com/apache/lucene/pull/13260#discussion_r1550266166
########## lucene/test-framework/src/java/org/apache/lucene/tests/util/hnsw/HnswTestUtil.java: ########## @@ -0,0 +1,132 @@ +/* + * 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.lucene.tests.util.hnsw; + +import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS; + +import java.io.IOException; +import java.util.ArrayDeque; +import java.util.ArrayList; +import java.util.Deque; +import java.util.List; +import org.apache.lucene.codecs.HnswGraphProvider; +import org.apache.lucene.codecs.perfield.PerFieldKnnVectorsFormat; +import org.apache.lucene.index.CodecReader; +import org.apache.lucene.index.IndexReader; +import org.apache.lucene.index.LeafReaderContext; +import org.apache.lucene.util.FixedBitSet; +import org.apache.lucene.util.hnsw.HnswGraph; + +/** Utilities for use in tests involving HNSW graphs */ +public class HnswTestUtil { + + /** + * Returns true iff level 0 of the graph is fully connected - that is every node is reachable from + * any entry point. + */ + public static boolean isFullyConnected(HnswGraph knnValues) throws IOException { + return componentSizes(knnValues).size() < 2; + } + + /** + * Returns the sizes of the distinct graph components on level 0. If the graph is fully-connected + * there will only be a single component. If the graph is empty, the returned list will be empty. + */ + public static List<Integer> componentSizes(HnswGraph hnsw) throws IOException { + List<Integer> sizes = new ArrayList<>(); + FixedBitSet connectedNodes = new FixedBitSet(hnsw.size()); + assert hnsw.size() == hnsw.getNodesOnLevel(0).size(); + System.out.println("size=" + hnsw.size()); + int total = 0; + while (total < connectedNodes.length()) { + int componentSize = traverseConnectedNodes(hnsw, connectedNodes); + assert componentSize > 0; + sizes.add(componentSize); + total += componentSize; + } + return sizes; + } + + // count the nodes in a connected component of the graph and set the bits of its nodes in + // connectedNodes bitset + private static int traverseConnectedNodes(HnswGraph hnswGraph, FixedBitSet connectedNodes) + throws IOException { + // Start at entry point and search all nodes on this level + int entryPoint = nextClearBit(connectedNodes, 0); + if (entryPoint == NO_MORE_DOCS) { + return 0; + } + Deque<Integer> stack = new ArrayDeque<>(); + stack.push(entryPoint); + int count = 0; + while (!stack.isEmpty()) { + int node = stack.pop(); + if (connectedNodes.get(node)) { + continue; + } + count++; + connectedNodes.set(node); + hnswGraph.seek(0, node); + int friendOrd; + while ((friendOrd = hnswGraph.nextNeighbor()) != NO_MORE_DOCS) { + stack.push(friendOrd); + } + } + return count; + } + + private static int nextClearBit(FixedBitSet bits, int index) { + // Depends on the ghost bits being clear! + long[] barray = bits.getBits(); + assert index >= 0 && index < bits.length() : "index=" + index + ", numBits=" + bits.length(); + int i = index >> 6; + long word = ~(barray[i] >> index); // skip all the bits to the right of index + + if (word != 0) { + return index + Long.numberOfTrailingZeros(word); + } + + while (++i < barray.length) { + word = ~barray[i]; + if (word != 0) { + int next = (i << 6) + Long.numberOfTrailingZeros(word); + if (next >= bits.length()) { + return NO_MORE_DOCS; + } else { + return next; + } + } + } + return NO_MORE_DOCS; + } Review Comment: This function seems to be motivated from `FixedBitSet#nextSetBit` and would be more suitable for `FixedBitSet` class?....I wonder why it does not have it already. ########## lucene/test-framework/src/java/org/apache/lucene/tests/util/hnsw/HnswTestUtil.java: ########## @@ -0,0 +1,132 @@ +/* + * 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.lucene.tests.util.hnsw; + +import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS; + +import java.io.IOException; +import java.util.ArrayDeque; +import java.util.ArrayList; +import java.util.Deque; +import java.util.List; +import org.apache.lucene.codecs.HnswGraphProvider; +import org.apache.lucene.codecs.perfield.PerFieldKnnVectorsFormat; +import org.apache.lucene.index.CodecReader; +import org.apache.lucene.index.IndexReader; +import org.apache.lucene.index.LeafReaderContext; +import org.apache.lucene.util.FixedBitSet; +import org.apache.lucene.util.hnsw.HnswGraph; + +/** Utilities for use in tests involving HNSW graphs */ +public class HnswTestUtil { + + /** + * Returns true iff level 0 of the graph is fully connected - that is every node is reachable from + * any entry point. + */ + public static boolean isFullyConnected(HnswGraph knnValues) throws IOException { + return componentSizes(knnValues).size() < 2; + } + + /** + * Returns the sizes of the distinct graph components on level 0. If the graph is fully-connected + * there will only be a single component. If the graph is empty, the returned list will be empty. + */ + public static List<Integer> componentSizes(HnswGraph hnsw) throws IOException { Review Comment: It seems like the purpose of this function is to be a utility for future use cases(if any) because if we only need to know the graph is fully connected we could just pick a node and traverse only once to check if its size is equal to graph size i.e. early terminate instead of going through all components. Alternatively, I think we should keep `componentSizes` as-is but implement `isFullyConnected` like below? ```java public static boolean isFullyConnected(HnswGraph hnsw) throws IOException { FixedBitSet connectedNodes = new FixedBitSet(hnsw.size()); assert hnsw.size() == hnsw.getNodesOnLevel(0).size(); System.out.println("size=" + hnsw.size()); return connectedNodes.length() == traverseConnectedNodes(hnsw, connectedNodes); } ``` -- 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: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
