Added null checks for fieldInfo in ExactSearcher to avoid NPE while r…

…unning exact search for segments with no vector field

Signed-off-by: Navneet Verma <[email protected]>

CHANGELOG.md

@@ -19,11 +19,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Enhancements
 - Introduced a writing layer in native engines where relies on the writing interface to process IO. (#2241)[https://github.com/opensearch-project/k-NN/pull/2241]
 ### Bug Fixes
-* Fix NPE in ANN search when a segment doesn't contain vector field (#2278)[https://github.com/opensearch-project/k-NN/pull/2278]
+* Fixing the bug when a segment has no vector field present for disk based vector search (#2282)[https://github.com/opensearch-project/k-NN/pull/2282]
 ### Infrastructure
 * Updated C++ version in JNI from c++11 to c++17 [#2259](https://github.com/opensearch-project/k-NN/pull/2259)
 * Upgrade bytebuddy and objenesis version to match OpenSearch core and, update github ci runner for macos [#2279](https://github.com/opensearch-project/k-NN/pull/2279)
 ### Documentation
 ### Maintenance
 * Select index settings based on cluster version[2236](https://github.com/opensearch-project/k-NN/pull/2236)
+* Added null checks for fieldInfo in ExactSearcher to avoid NPE while running exact search for segments with no vector field (#2278)[https://github.com/opensearch-project/k-NN/pull/2278]
 ### Refactoring

src/main/java/org/opensearch/knn/common/FieldInfoExtractor.java

@@ -8,6 +8,8 @@
 import lombok.experimental.UtilityClass;
 import org.apache.commons.lang.StringUtils;
 import org.apache.lucene.index.FieldInfo;
+import org.apache.lucene.index.LeafReader;
+import org.opensearch.common.Nullable;
 import org.opensearch.knn.index.SpaceType;
 import org.opensearch.knn.index.VectorDataType;
 import org.opensearch.knn.index.engine.KNNEngine;
@@ -27,7 +29,7 @@
 import static org.opensearch.knn.common.KNNConstants.SPACE_TYPE;
 
 /**
- * A utility class to extract information from FieldInfo.
+ * A utility class to extract information from FieldInfo and also provides utility functions to extract fieldInfo
  */
 @UtilityClass
 public class FieldInfoExtractor {
@@ -103,4 +105,15 @@ public static SpaceType getSpaceType(final ModelDao modelDao, final FieldInfo fi
         }
         return modelMetadata.getSpaceType();
     }
+
+    /**
+     * Get the field info for the given field name, do a null check on the fieldInfo, as this function can return null,
+     * if the field is not found.
+     * @param leafReader {@link LeafReader}
+     * @param fieldName {@link String}
+     * @return {@link FieldInfo}
+     */
+    public static @Nullable FieldInfo getFieldInfo(final LeafReader leafReader, final String fieldName) {
+        return leafReader.getFieldInfos().fieldInfo(fieldName);
+    }
 }

src/main/java/org/opensearch/knn/index/KNNVectorDVLeafFieldData.java

@@ -12,6 +12,7 @@
 import org.opensearch.index.fielddata.LeafFieldData;
 import org.opensearch.index.fielddata.ScriptDocValues;
 import org.opensearch.index.fielddata.SortedBinaryDocValues;
+import org.opensearch.knn.common.FieldInfoExtractor;
 
 import java.io.IOException;
 
@@ -40,7 +41,7 @@ public long ramBytesUsed() {
     @Override
     public ScriptDocValues<float[]> getScriptValues() {
         try {
-            FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(fieldName);
+            FieldInfo fieldInfo = FieldInfoExtractor.getFieldInfo(reader, fieldName);
             if (fieldInfo == null) {
                 return KNNVectorScriptDocValues.emptyValues(fieldName, vectorDataType);
             }

src/main/java/org/opensearch/knn/index/query/ExactSearcher.java

@@ -38,6 +38,7 @@
 import org.opensearch.knn.indices.ModelDao;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Locale;
 import java.util.Map;
@@ -59,7 +60,11 @@ public class ExactSearcher {
      */
     public Map<Integer, Float> searchLeaf(final LeafReaderContext leafReaderContext, final ExactSearcherContext exactSearcherContext)
         throws IOException {
-        KNNIterator iterator = getKNNIterator(leafReaderContext, exactSearcherContext);
+        final KNNIterator iterator = getKNNIterator(leafReaderContext, exactSearcherContext);
+        // because of any reason if we are not able to get KNNIterator, return an empty map
+        if (iterator == null) {
+            return Collections.emptyMap();
+        }
         if (exactSearcherContext.getKnnQuery().getRadius() != null) {
             return doRadialSearch(leafReaderContext, exactSearcherContext, iterator);
         }
@@ -74,8 +79,8 @@ public Map<Integer, Float> searchLeaf(final LeafReaderContext leafReaderContext,
      * Perform radial search by comparing scores with min score. Currently, FAISS from native engine supports radial search.
      * Hence, we assume that Radius from knnQuery is always distance, and we convert it to score since we do exact search uses scores
      * to filter out the documents that does not have given min score.
-     * @param leafReaderContext
-     * @param exactSearcherContext
+     * @param leafReaderContext {@link LeafReaderContext}
+     * @param exactSearcherContext {@link ExactSearcherContext}
      * @param iterator {@link KNNIterator}
      * @return Map of docId and score
      * @throws IOException exception raised by iterator during traversal
@@ -87,7 +92,10 @@ private Map<Integer, Float> doRadialSearch(
     ) throws IOException {
         final SegmentReader reader = Lucene.segmentReader(leafReaderContext.reader());
         final KNNQuery knnQuery = exactSearcherContext.getKnnQuery();
-        final FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(knnQuery.getField());
+        final FieldInfo fieldInfo = FieldInfoExtractor.getFieldInfo(reader, knnQuery.getField());
+        if (fieldInfo == null) {
+            return Collections.emptyMap();
+        }
         final KNNEngine engine = FieldInfoExtractor.extractKNNEngine(fieldInfo);
         if (KNNEngine.FAISS != engine) {
             throw new IllegalArgumentException(String.format(Locale.ROOT, "Engine [%s] does not support radial search", engine));
@@ -149,7 +157,11 @@ private KNNIterator getKNNIterator(LeafReaderContext leafReaderContext, ExactSea
         final KNNQuery knnQuery = exactSearcherContext.getKnnQuery();
         final BitSet matchedDocs = exactSearcherContext.getMatchedDocs();
         final SegmentReader reader = Lucene.segmentReader(leafReaderContext.reader());
-        final FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(knnQuery.getField());
+        final FieldInfo fieldInfo = FieldInfoExtractor.getFieldInfo(reader, knnQuery.getField());
+        if (fieldInfo == null) {
+            log.debug("[KNN] Cannot get KNNIterator as Field info not found for {}:{}", knnQuery.getField(), reader.getSegmentName());
+            return null;
+        }
         final SpaceType spaceType = FieldInfoExtractor.getSpaceType(modelDao, fieldInfo);
 
         boolean isNestedRequired = exactSearcherContext.isParentHits() && knnQuery.getParentsFilter() != null;

src/main/java/org/opensearch/knn/index/query/KNNWeight.java

@@ -227,7 +227,7 @@ private Map<Integer, Float> doANNSearch(
     ) throws IOException {
         final SegmentReader reader = Lucene.segmentReader(context.reader());
 
-        FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(knnQuery.getField());
+        FieldInfo fieldInfo = FieldInfoExtractor.getFieldInfo(reader, knnQuery.getField());
 
         if (fieldInfo == null) {
             log.debug("[KNN] Field info not found for {}:{}", knnQuery.getField(), reader.getSegmentName());
@@ -479,7 +479,7 @@ private boolean isFilteredExactSearchRequireAfterANNSearch(final int filterIdsCo
      */
     private boolean isMissingNativeEngineFiles(LeafReaderContext context) {
         final SegmentReader reader = Lucene.segmentReader(context.reader());
-        final FieldInfo fieldInfo = reader.getFieldInfos().fieldInfo(knnQuery.getField());
+        final FieldInfo fieldInfo = FieldInfoExtractor.getFieldInfo(reader, knnQuery.getField());
         // if segment has no documents with at least 1 vector field, field info will be null
         if (fieldInfo == null) {
             return false;

src/test/java/org/opensearch/knn/common/FieldInfoExtractorTests.java

@@ -6,6 +6,8 @@
 package org.opensearch.knn.common;
 
 import org.apache.lucene.index.FieldInfo;
+import org.apache.lucene.index.FieldInfos;
+import org.apache.lucene.index.LeafReader;
 import org.junit.Assert;
 import org.mockito.MockedStatic;
 import org.mockito.Mockito;
@@ -63,4 +65,15 @@ public void testExtractVectorDataType() {
         when(fieldInfo.getAttribute("model_id")).thenReturn(null);
         assertEquals(VectorDataType.DEFAULT, FieldInfoExtractor.extractVectorDataType(fieldInfo));
     }
+
+    public void testGetFieldInfo_whenDifferentInput_thenSuccess() {
+        LeafReader leafReader = Mockito.mock(LeafReader.class);
+        FieldInfos fieldInfos = Mockito.mock(FieldInfos.class);
+        FieldInfo fieldInfo = Mockito.mock(FieldInfo.class);
+        Mockito.when(leafReader.getFieldInfos()).thenReturn(fieldInfos);
+        Mockito.when(fieldInfos.fieldInfo("invalid")).thenReturn(null);
+        Mockito.when(fieldInfos.fieldInfo("valid")).thenReturn(fieldInfo);
+        Assert.assertNull(FieldInfoExtractor.getFieldInfo(leafReader, "invalid"));
+        Assert.assertEquals(fieldInfo, FieldInfoExtractor.getFieldInfo(leafReader, "valid"));
+    }
 }

src/test/java/org/opensearch/knn/index/query/ExactSearcherTests.java

@@ -20,6 +20,7 @@
 import org.mockito.Mockito;
 import org.opensearch.knn.KNNTestCase;
 import org.opensearch.knn.index.SpaceType;
+import org.opensearch.knn.index.VectorDataType;
 import org.opensearch.knn.index.codec.KNNCodecVersion;
 import org.opensearch.knn.index.engine.KNNEngine;
 import org.opensearch.knn.index.vectorvalues.KNNFloatVectorValues;
@@ -50,6 +51,50 @@ public class ExactSearcherTests extends KNNTestCase {
 
     private static final String SEGMENT_NAME = "0";
 
+    @SneakyThrows
+    public void testExactSearch_whenSegmentHasNoVectorField_thenNoDocsReturned() {
+        final float[] queryVector = new float[] { 0.1f, 2.0f, 3.0f };
+        final KNNQuery query = KNNQuery.builder().field(FIELD_NAME).queryVector(queryVector).k(10).indexName(INDEX_NAME).build();
+
+        final ExactSearcher.ExactSearcherContext.ExactSearcherContextBuilder exactSearcherContextBuilder =
+            ExactSearcher.ExactSearcherContext.builder().knnQuery(query);
+
+        ExactSearcher exactSearcher = new ExactSearcher(null);
+        final LeafReaderContext leafReaderContext = mock(LeafReaderContext.class);
+        final SegmentReader reader = mock(SegmentReader.class);
+        when(leafReaderContext.reader()).thenReturn(reader);
+
+        final FSDirectory directory = mock(FSDirectory.class);
+        final SegmentInfo segmentInfo = new SegmentInfo(
+            directory,
+            Version.LATEST,
+            Version.LATEST,
+            SEGMENT_NAME,
+            100,
+            false,
+            false,
+            KNNCodecVersion.current().getDefaultCodecDelegate(),
+            Map.of(),
+            new byte[StringHelper.ID_LENGTH],
+            Map.of(),
+            Sort.RELEVANCE
+        );
+        segmentInfo.setFiles(Set.of());
+        final SegmentCommitInfo segmentCommitInfo = new SegmentCommitInfo(segmentInfo, 0, 0, 0, 0, 0, new byte[StringHelper.ID_LENGTH]);
+        when(reader.getSegmentInfo()).thenReturn(segmentCommitInfo);
+
+        final Path path = mock(Path.class);
+        when(directory.getDirectory()).thenReturn(path);
+        final FieldInfos fieldInfos = mock(FieldInfos.class);
+        final FieldInfo fieldInfo = mock(FieldInfo.class);
+        when(reader.getFieldInfos()).thenReturn(fieldInfos);
+        when(fieldInfos.fieldInfo(query.getField())).thenReturn(null);
+        when(fieldInfo.attributes()).thenReturn(Collections.emptyMap());
+        Map<Integer, Float> docIds = exactSearcher.searchLeaf(leafReaderContext, exactSearcherContextBuilder.build());
+        Mockito.verify(fieldInfos).fieldInfo(query.getField());
+        assertEquals(0, docIds.size());
+    }
+
     @SneakyThrows
     public void testRadialSearch_whenNoEngineFiles_thenSuccess() {
         try (MockedStatic<KNNVectorValuesFactory> valuesFactoryMockedStatic = Mockito.mockStatic(KNNVectorValuesFactory.class)) {
@@ -75,6 +120,7 @@ public void testRadialSearch_whenNoEngineFiles_thenSuccess() {
                 .queryVector(queryVector)
                 .radius(radius)
                 .indexName(INDEX_NAME)
+                .vectorDataType(VectorDataType.FLOAT)
                 .context(context)
                 .build();