Reorginize factory and facade code, minor review comments

Signed-off-by: Martin Gaievski <[email protected]>

src/main/java/org/opensearch/knn/index/codec/KNN91Codec/KNN91Codec.java

@@ -1,23 +1,17 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec.KNN91Codec;
 
 import org.apache.lucene.codecs.Codec;
 import org.apache.lucene.codecs.CompoundFormat;
 import org.apache.lucene.codecs.DocValuesFormat;
 import org.apache.lucene.codecs.FilterCodec;
-import org.apache.lucene.codecs.lucene91.Lucene91Codec;
-import org.opensearch.knn.index.codec.KNNDocFormatFacade;
-import org.opensearch.knn.index.codec.KNNDocFormatFactory;
+import org.opensearch.knn.index.codec.KNNFormatFacade;
+import org.opensearch.knn.index.codec.KNNFormatFactory;
+
+import static org.opensearch.knn.index.codec.KNNCodecFactory.CodecDelegateFactory.createKNN91DefaultDelegate;
 
 /**
  * Extends the Codec to support a new file format for KNN index
@@ -27,13 +21,13 @@
 public final class KNN91Codec extends FilterCodec {
 
     public static final String KNN_91 = "KNN91Codec";
-    private KNNDocFormatFacade docFormatFacade;
+    private KNNFormatFacade knnFormatFacade;
 
     /**
      * No arg constructor that uses Lucene91 as the delegate
      */
     public KNN91Codec() {
-        this(new Lucene91Codec());
+        this(createKNN91DefaultDelegate());
     }
 
     /**
@@ -43,16 +37,16 @@ public KNN91Codec() {
      */
     public KNN91Codec(Codec delegate) {
         super(KNN_91, delegate);
-        docFormatFacade = KNNDocFormatFactory.createKNN91DocFormat(delegate);
+        knnFormatFacade = KNNFormatFactory.createKNN91Format(delegate);
     }
 
     @Override
     public DocValuesFormat docValuesFormat() {
-        return docFormatFacade.docValuesFormat();
+        return knnFormatFacade.docValuesFormat();
     }
 
     @Override
     public CompoundFormat compoundFormat() {
-        return docFormatFacade.compoundFormat();
+        return knnFormatFacade.compoundFormat();
     }
 }

src/main/java/org/opensearch/knn/index/codec/KNN91Codec/docformat/KNN91BinaryDocValues.java

@@ -1,14 +1,7 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec.KNN91Codec.docformat;
 
 import org.apache.lucene.index.BinaryDocValues;

src/main/java/org/opensearch/knn/index/codec/KNN91Codec/docformat/KNN91CompoundFormat.java

@@ -1,14 +1,7 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec.KNN91Codec.docformat;
 
 import org.apache.lucene.codecs.CompoundDirectory;

src/main/java/org/opensearch/knn/index/codec/KNN91Codec/docformat/KNN91DocValuesConsumer.java

@@ -1,14 +1,7 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec.KNN91Codec.docformat;
 
 import com.google.common.collect.ImmutableMap;

src/main/java/org/opensearch/knn/index/codec/KNN91Codec/docformat/KNN91DocValuesFormat.java

@@ -1,20 +1,12 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec.KNN91Codec.docformat;
 
 import org.apache.lucene.codecs.DocValuesConsumer;
 import org.apache.lucene.codecs.DocValuesFormat;
 import org.apache.lucene.codecs.DocValuesProducer;
-import org.apache.lucene.codecs.lucene90.Lucene90DocValuesFormat;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.SegmentWriteState;
 
@@ -26,10 +18,6 @@
 public class KNN91DocValuesFormat extends DocValuesFormat {
     private final DocValuesFormat delegate;
 
-    public KNN91DocValuesFormat() {
-        this(new Lucene90DocValuesFormat());
-    }
-
     /**
      * Constructor that takes delegate in order to handle non-overridden methods
      *

src/main/java/org/opensearch/knn/index/codec/KNN91Codec/docformat/KNN91DocValuesReader.java

@@ -1,14 +1,7 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec.KNN91Codec.docformat;
 
 import org.apache.lucene.codecs.DocValuesProducer;

src/main/java/org/opensearch/knn/index/codec/KNNCodecFactory.java

@@ -1,25 +1,52 @@
 /*
+ * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- *
- * The OpenSearch Contributors require contributions made to
- * this file be licensed under the Apache-2.0 license or a
- * compatible open source license.
- *
- * Modifications Copyright OpenSearch Contributors. See
- * GitHub history for details.
  */
-
 package org.opensearch.knn.index.codec;
 
+import com.google.common.collect.ImmutableMap;
 import org.apache.lucene.codecs.Codec;
+import org.apache.lucene.codecs.lucene91.Lucene91Codec;
 import org.opensearch.knn.index.codec.KNN91Codec.KNN91Codec;
 
+import java.lang.reflect.Constructor;
+import java.util.Map;
+
 /**
  * Factory abstraction for KNN codes
  */
 public class KNNCodecFactory {
 
-    public static Codec createKNN91Codec(Codec userCodec) {
-        return new KNN91Codec(userCodec);
+    private static Map<KNNCodecVersion, Class> CODEC_BY_VERSION = ImmutableMap.of(KNNCodecVersion.KNN91, KNN91Codec.class);
+
+    private static KNNCodecVersion LATEST_KNN_CODEC_VERSION = KNNCodecVersion.KNN91;
+
+    public static Codec createKNNCodec(final Codec userCodec) {
+        return getCodec(LATEST_KNN_CODEC_VERSION, userCodec);
+    }
+
+    public static Codec createKNNCodec(final KNNCodecVersion knnCodecVersion, final Codec userCodec) {
+        return getCodec(knnCodecVersion, userCodec);
+    }
+
+    private static Codec getCodec(final KNNCodecVersion knnCodecVersion, final Codec userCodec) {
+        try {
+            Constructor<?> constructor = CODEC_BY_VERSION.getOrDefault(knnCodecVersion, CODEC_BY_VERSION.get(LATEST_KNN_CODEC_VERSION))
+                .getConstructor(Codec.class);
+            return (Codec) constructor.newInstance(userCodec);
+        } catch (Exception ex) {
+            throw new RuntimeException("Cannot create instance of KNN codec", ex);
+        }
+    }
+
+    public static class CodecDelegateFactory {
+
+        public static Codec createKNN91DefaultDelegate() {
+            return new Lucene91Codec();
+        }
+    }
+
+    enum KNNCodecVersion {
+        KNN91
     }
 }

src/main/java/org/opensearch/knn/index/codec/KNNCodecService.java

@@ -26,6 +26,6 @@ public KNNCodecService(CodecServiceConfig codecServiceConfig) {
      */
     @Override
     public Codec codec(String name) {
-        return KNNCodecFactory.createKNN91Codec(super.codec(name));
+        return KNNCodecFactory.createKNNCodec(super.codec(name));
     }
 }

src/main/java/org/opensearch/knn/index/codec/KNNFormatFacade.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.opensearch.knn.index.codec;
+
+import org.apache.lucene.codecs.CompoundFormat;
+import org.apache.lucene.codecs.DocValuesFormat;
+
+/**
+ * Class abstracts facade for plugin formats.
+ */
+public class KNNFormatFacade {
+
+    private final DocValuesFormat docValuesFormat;
+    private final CompoundFormat compoundFormat;
+
+    public KNNFormatFacade(final DocValuesFormat docValuesFormat, final CompoundFormat compoundFormat) {
+        this.docValuesFormat = docValuesFormat;
+        this.compoundFormat = compoundFormat;
+    }
+
+    public DocValuesFormat docValuesFormat() {
+        return docValuesFormat;
+    }
+
+    public CompoundFormat compoundFormat() {
+        return compoundFormat;
+    }
+}

src/main/java/org/opensearch/knn/index/codec/KNNFormatFactory.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.opensearch.knn.index.codec;
+
+import org.apache.lucene.codecs.Codec;
+import org.opensearch.knn.index.codec.KNN91Codec.docformat.KNN91CompoundFormat;
+import org.opensearch.knn.index.codec.KNN91Codec.docformat.KNN91DocValuesFormat;
+
+/**
+ * Factory abstraction for KNN document format facades
+ */
+public class KNNFormatFactory {
+
+    public static KNNFormatFacade createKNN91Format(final Codec delegate) {
+        final KNNFormatFacade knnFormatFacade = new KNNFormatFacade(
+            new KNN91DocValuesFormat(delegate.docValuesFormat()),
+            new KNN91CompoundFormat(delegate.compoundFormat())
+        );
+        return knnFormatFacade;
+    }
+}