expose knn format and update test

Author: ChrisHegarty

lucene/sandbox/src/java/module-info.java

@@ -40,10 +40,8 @@
 
   provides org.apache.lucene.codecs.PostingsFormat with
       org.apache.lucene.sandbox.codecs.idversion.IDVersionPostingsFormat;
-   provides org.apache.lucene.codecs.KnnVectorsFormat with
+  provides org.apache.lucene.codecs.KnnVectorsFormat with
       org.apache.lucene.sandbox.vectorsearch.CuVSVectorsFormat;
-//  provides org.apache.lucene.codecs.Codec with
-//      org.apache.lucene.sandbox.vectorsearch.CuVSCodec;
   provides com.nvidia.cuvs.spi.CuVSServiceProvider with
       org.apache.lucene.sandbox.vectorsearch.FilterCuVSServiceProvider;
 }

lucene/sandbox/src/java/org/apache/lucene/sandbox/vectorsearch/CagraFieldVectorsWriter.java

@@ -17,7 +17,6 @@
 package org.apache.lucene.sandbox.vectorsearch;
 
 import java.io.IOException;
-import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.concurrent.ConcurrentHashMap;
 import org.apache.lucene.codecs.KnnFieldVectorsWriter;

lucene/sandbox/src/java/org/apache/lucene/sandbox/vectorsearch/CuVSVectorsFormat.java

@@ -31,6 +31,10 @@ public class CuVSVectorsFormat extends KnnVectorsFormat {
   public static final String VECTOR_DATA_EXTENSION = "cag";
   public static final String META_EXTENSION = "cagmf";
   public static final int VERSION_CURRENT = 0;
+  public static final int DEFAULT_WRITER_THREADS = 1;
+  public static final int DEFAULT_INTERMEDIATE_GRAPH_DEGREE = 128;
+  public static final int DEFAULT_GRAPH_DEGREE = 64;
+
   public final int maxDimensions = 4096;
   public final int cuvsWriterThreads;
   public final int intGraphDegree;
@@ -39,15 +43,11 @@ public class CuVSVectorsFormat extends KnnVectorsFormat {
   public static CuVSResources resources;
 
   public CuVSVectorsFormat() {
-    super("CuVSVectorsFormat");
-    this.cuvsWriterThreads = 1;
-    this.intGraphDegree = 128;
-    this.graphDegree = 64;
-    try {
-      resources = CuVSResources.create();
-    } catch (Throwable e) {
-      throw new RuntimeException(e);
-    }
+    this(
+        DEFAULT_WRITER_THREADS,
+        DEFAULT_INTERMEDIATE_GRAPH_DEGREE,
+        DEFAULT_GRAPH_DEGREE,
+        MergeStrategy.NON_TRIVIAL_MERGE);
   }
 
   public CuVSVectorsFormat(

lucene/sandbox/src/java/org/apache/lucene/sandbox/vectorsearch/CuVSVectorsReader.java

@@ -145,8 +145,7 @@ private Map<String, List<CuVSIndex>> loadCuVSIndex(ZipInputStream zis, boolean i
           }
         case "vec":
           {
-            vectors.put(
-                segmentField, SerializationUtils.deserialize(baos.toByteArray()));
+            vectors.put(segmentField, SerializationUtils.deserialize(baos.toByteArray()));
             break;
           }
         case "map":

lucene/sandbox/src/resources/META-INF/services/org.apache.lucene.codecs.Codec

@@ -66,7 +66,7 @@ public class TestCuVS extends LuceneTestCase {
   public static void beforeClass() throws Exception {
     directory = newDirectory();
 
-    Codec codec = new CuVSCodec();
+    Codec codec = TestUtil.alwaysKnnVectorsFormat(new CuVSVectorsFormat());
 
     RandomIndexWriter writer =
         new RandomIndexWriter(
@@ -105,8 +105,8 @@ public static void beforeClass() throws Exception {
 
   @AfterClass
   public static void afterClass() throws Exception {
-    reader.close();
-    directory.close();
+    if (reader != null) reader.close();
+    if (directory != null) directory.close();
     searcher = null;
     reader = null;
     directory = null;