kaivalnp commented on code in PR #14178: URL: https://github.com/apache/lucene/pull/14178#discussion_r1940738982
########## lucene/sandbox/src/java22/org/apache/lucene/sandbox/codecs/faiss/LibFaissC.java: ########## @@ -0,0 +1,268 @@ +/* + * 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.sandbox.codecs.faiss; + +import static java.lang.foreign.ValueLayout.ADDRESS; +import static java.lang.foreign.ValueLayout.JAVA_FLOAT; +import static java.lang.foreign.ValueLayout.JAVA_INT; +import static java.lang.foreign.ValueLayout.JAVA_LONG; + +import java.lang.foreign.Arena; +import java.lang.foreign.FunctionDescriptor; +import java.lang.foreign.Linker; +import java.lang.foreign.MemoryLayout; +import java.lang.foreign.MemorySegment; +import java.lang.foreign.SymbolLookup; +import java.lang.invoke.MethodHandle; +import java.nio.ByteOrder; +import java.nio.FloatBuffer; +import java.util.Locale; +import org.apache.lucene.index.FloatVectorValues; +import org.apache.lucene.index.KnnVectorValues; +import org.apache.lucene.index.VectorSimilarityFunction; +import org.apache.lucene.search.KnnCollector; +import org.apache.lucene.util.Bits; + +public final class LibFaissC { + public static final String LIBRARY_VERSION = "1.9.0"; + + static { + try { + System.loadLibrary("faiss_c"); + } catch (UnsatisfiedLinkError e) { + throw new RuntimeException( + "Shared library not found, build the Faiss C_API from https://github.com/facebookresearch/faiss/blob/main/c_api/INSTALL.md " + + "and link it (along with all dependencies) to the library path " + + "(-Djava.library.path JVM argument or $LD_LIBRARY_PATH environment variable)", + e); + } + checkLibraryVersion(); + } + + private LibFaissC() {} + + private static MethodHandle getMethodHandle( + String functionName, MemoryLayout resLayout, MemoryLayout... argLayouts) { + return Linker.nativeLinker() + .downcallHandle( + SymbolLookup.loaderLookup().find(functionName).orElseThrow(), + FunctionDescriptor.of(resLayout, argLayouts)); + } + + private static void checkLibraryVersion() { + MethodHandle getVersion = getMethodHandle("faiss_get_version", ADDRESS); + String actualVersion = callAndGetString(getVersion); + if (LIBRARY_VERSION.equals(actualVersion) == false) { + throw new UnsupportedOperationException( + String.format( + Locale.ROOT, + "Expected Faiss library version %s, found %s", + LIBRARY_VERSION, + actualVersion)); + } + } + + private static final MethodHandle FREE_INDEX = + getMethodHandle("faiss_Index_free", JAVA_INT, ADDRESS); + + public static void freeIndex(MemorySegment indexPointer) { + callAndHandleError(FREE_INDEX, indexPointer); + } + + private static final MethodHandle FREE_PARAMETER_SPACE = + getMethodHandle("faiss_ParameterSpace_free", JAVA_INT, ADDRESS); + + private static void freeParameterSpace(MemorySegment parameterSpacePointer) { + callAndHandleError(FREE_PARAMETER_SPACE, parameterSpacePointer); + } + + private static final MethodHandle INDEX_FACTORY = + getMethodHandle("faiss_index_factory", JAVA_INT, ADDRESS, JAVA_INT, ADDRESS, JAVA_INT); + + private static final MethodHandle PARAMETER_SPACE_NEW = + getMethodHandle("faiss_ParameterSpace_new", JAVA_INT, ADDRESS); + + private static final MethodHandle SET_INDEX_PARAMETERS = + getMethodHandle( + "faiss_ParameterSpace_set_index_parameters", JAVA_INT, ADDRESS, ADDRESS, ADDRESS); + + private static final MethodHandle INDEX_IS_TRAINED = + getMethodHandle("faiss_Index_is_trained", JAVA_INT, ADDRESS); + + private static final MethodHandle INDEX_TRAIN = + getMethodHandle("faiss_Index_train", JAVA_INT, ADDRESS, JAVA_LONG, ADDRESS); + + private static final MethodHandle INDEX_ADD = + getMethodHandle("faiss_Index_add", JAVA_INT, ADDRESS, JAVA_LONG, ADDRESS); + + public record Index(MemorySegment indexPointer, int[] ordToDoc) {} + + public static Index createIndex( + String description, + String indexParams, + VectorSimilarityFunction function, + FloatVectorValues floatVectorValues) { + + try (Arena temp = Arena.ofConfined()) { + int size = floatVectorValues.size(); + int dimension = floatVectorValues.dimension(); + + // Mapped from faiss/MetricType.h + int metric = + switch (function) { + case DOT_PRODUCT -> 0; + case EUCLIDEAN -> 1; + default -> throw new UnsupportedOperationException("metric type not supported"); + }; + + // Create an index + MemorySegment pointer = temp.allocate(ADDRESS); + callAndHandleError(INDEX_FACTORY, pointer, dimension, temp.allocateFrom(description), metric); + MemorySegment indexPointer = pointer.get(ADDRESS, 0); + + // Set index params + callAndHandleError(PARAMETER_SPACE_NEW, pointer); + MemorySegment parameterSpacePointer = + pointer.get(ADDRESS, 0).reinterpret(temp, LibFaissC::freeParameterSpace); + callAndHandleError( + SET_INDEX_PARAMETERS, + parameterSpacePointer, + indexPointer, + temp.allocateFrom(indexParams)); + + // Allocate docs in native memory + MemorySegment docs = temp.allocate(JAVA_FLOAT, (long) size * dimension); + FloatBuffer docsBuffer = docs.asByteBuffer().order(ByteOrder.nativeOrder()).asFloatBuffer(); + + int[] ordToDoc = new int[size]; + KnnVectorValues.DocIndexIterator iterator = floatVectorValues.iterator(); + for (int i = 0; i < size; i++) { + ordToDoc[i] = iterator.nextDoc(); + docsBuffer.put(floatVectorValues.vectorValue(iterator.index())); + } + + // Train index + if ((int) INDEX_IS_TRAINED.invokeExact(indexPointer) == 0) { + callAndHandleError(INDEX_TRAIN, indexPointer, size, docs); + } + + // Add docs to index + callAndHandleError(INDEX_ADD, indexPointer, size, docs); + + return new Index(indexPointer, ordToDoc); + } catch (Throwable t) { + throw new RuntimeException(t); + } + } + + private static final MethodHandle INDEX_WRITE = + getMethodHandle("faiss_write_index_fname", JAVA_INT, ADDRESS, ADDRESS); + + public static void indexWrite(MemorySegment indexPointer, String fileName) { + try (Arena temp = Arena.ofConfined()) { + callAndHandleError(INDEX_WRITE, indexPointer, temp.allocateFrom(fileName)); + } + } + + private static final MethodHandle INDEX_READ = + getMethodHandle("faiss_read_index_fname", JAVA_INT, ADDRESS, JAVA_INT, ADDRESS); + + public static MemorySegment indexRead(String fileName, int ioFlags) { + try (Arena temp = Arena.ofConfined()) { + MemorySegment pointer = temp.allocate(ADDRESS); + callAndHandleError(INDEX_READ, temp.allocateFrom(fileName), ioFlags, pointer); + return pointer.get(ADDRESS, 0); + } + } + + private static final MethodHandle INDEX_SEARCH = + getMethodHandle( + "faiss_Index_search", JAVA_INT, ADDRESS, JAVA_LONG, ADDRESS, JAVA_INT, ADDRESS, ADDRESS); + + public static void indexSearch( + MemorySegment indexPointer, + int[] ordToDoc, + float[] query, + KnnCollector knnCollector, + Bits acceptDocs) { + try (Arena temp = Arena.ofConfined()) { + // Allocate queries in native memory + MemorySegment queries = temp.allocate(JAVA_FLOAT, query.length); + queries.asByteBuffer().order(ByteOrder.nativeOrder()).asFloatBuffer().put(query); + + // Faiss knn search + int k = knnCollector.k(); + MemorySegment distancesPointer = temp.allocate(JAVA_FLOAT, k); + MemorySegment idsPointer = temp.allocate(JAVA_LONG, k); + + MemorySegment localIndex = indexPointer.reinterpret(temp, null); + callAndHandleError(INDEX_SEARCH, localIndex, 1, queries, k, distancesPointer, idsPointer); + + // Retrieve scores + float[] distances = new float[k]; + distancesPointer.asByteBuffer().order(ByteOrder.nativeOrder()).asFloatBuffer().get(distances); + + // Retrieve ids + long[] ids = new long[k]; + idsPointer.asByteBuffer().order(ByteOrder.nativeOrder()).asLongBuffer().get(ids); + + // Record hits + for (int i = 0; i < k; i++) { + int ord = (int) ids[i]; + if (ord < 0) { + break; + } + + // TODO: This is like a post-filter, include at runtime? + int doc = ordToDoc[ord]; + if (acceptDocs == null || acceptDocs.get(doc)) { + knnCollector.collect(doc, distances[i]); + } Review Comment: (2) may not be straightforward, as the memory layout of structs is compiler dependent (and would cause bugs in case of a padding mismatch) -- so I'll try to avoid this The above PR is merged in Faiss, but did not make it in time for [`v1.10.0`](https://github.com/facebookresearch/faiss/releases/tag/v1.10.0) released \~3 days ago :( I wonder what the best course of action is for this PR: 1. Have users pull the above commit locally before building Faiss - Add ability to perform a filtered graph search (live docs or query-time filters) using [`IDSelectorBitmap`](https://github.com/facebookresearch/faiss/blob/3ec2fbdf0d56aec2667dc0f78ef977fae41d47af/c_api/impl/AuxIndexStructures_c.h#L90) - Local modifications to Faiss will not be needed after `v1.11.0` ([\~Q1 2025](https://github.com/orgs/facebookresearch/projects/27)) 2. Keep the PR as-is and use post-filtering - Add a TODO to use the new function after `v1.11.0` - Possibility of subpar, or incomplete results during this time 3. Use an expensive alternative to perform filtered search - Collect all live (or filtered) docs in a list and instantiate an [`IDSelectorBatch`](https://github.com/facebookresearch/faiss/blob/d243e628880676332263347817b3fe7f474b8b5b/c_api/impl/AuxIndexStructures_c.h#L80) - Slow performance for filtered searches, but correct results - Add a TODO to move to `IDSelectorBitmap` after `v1.11.0` Note: All these avoid any extra (or "glue") code to be compiled separately.. Please let me know if anyone has other suggestions I may have missed! -- 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. 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