Star tree codec changes (opensearch-project#14514)

---------
Signed-off-by: Bharathwaj G <bharath78910@gmail.com>

server/src/main/java/org/opensearch/index/codec/CodecService.java

@@ -39,6 +39,7 @@
 import org.opensearch.common.Nullable;
 import org.opensearch.common.collect.MapBuilder;
 import org.opensearch.index.IndexSettings;
+import org.opensearch.index.codec.composite.CompositeCodecFactory;
 import org.opensearch.index.mapper.MapperService;
 
 import java.util.Map;
@@ -63,6 +64,7 @@ public class CodecService {
      * the raw unfiltered lucene default. useful for testing
      */
     public static final String LUCENE_DEFAULT_CODEC = "lucene_default";
+    private final CompositeCodecFactory compositeCodecFactory = new CompositeCodecFactory();
 
     public CodecService(@Nullable MapperService mapperService, IndexSettings indexSettings, Logger logger) {
         final MapBuilder<String, Codec> codecs = MapBuilder.<String, Codec>newMapBuilder();
@@ -73,10 +75,16 @@ public CodecService(@Nullable MapperService mapperService, IndexSettings indexSe
             codecs.put(BEST_COMPRESSION_CODEC, new Lucene99Codec(Mode.BEST_COMPRESSION));
             codecs.put(ZLIB, new Lucene99Codec(Mode.BEST_COMPRESSION));
         } else {
-            codecs.put(DEFAULT_CODEC, new PerFieldMappingPostingFormatCodec(Mode.BEST_SPEED, mapperService, logger));
-            codecs.put(LZ4, new PerFieldMappingPostingFormatCodec(Mode.BEST_SPEED, mapperService, logger));
-            codecs.put(BEST_COMPRESSION_CODEC, new PerFieldMappingPostingFormatCodec(Mode.BEST_COMPRESSION, mapperService, logger));
-            codecs.put(ZLIB, new PerFieldMappingPostingFormatCodec(Mode.BEST_COMPRESSION, mapperService, logger));
+            // CompositeCodec still delegates to PerFieldMappingPostingFormatCodec
+            // We can still support all the compression codecs when composite index is present
+            if (mapperService.isCompositeIndexPresent()) {
+                codecs.putAll(compositeCodecFactory.getCompositeIndexCodecs(mapperService, logger));
+            } else {
+                codecs.put(DEFAULT_CODEC, new PerFieldMappingPostingFormatCodec(Mode.BEST_SPEED, mapperService, logger));
+                codecs.put(LZ4, new PerFieldMappingPostingFormatCodec(Mode.BEST_SPEED, mapperService, logger));
+                codecs.put(BEST_COMPRESSION_CODEC, new PerFieldMappingPostingFormatCodec(Mode.BEST_COMPRESSION, mapperService, logger));
+                codecs.put(ZLIB, new PerFieldMappingPostingFormatCodec(Mode.BEST_COMPRESSION, mapperService, logger));
+            }
         }
         codecs.put(LUCENE_DEFAULT_CODEC, Codec.getDefault());
         for (String codec : Codec.availableCodecs()) {

server/src/main/java/org/opensearch/index/codec/composite/Composite99Codec.java

@@ -0,0 +1,57 @@
+/*
+ * 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.
+ */
+
+package org.opensearch.index.codec.composite;
+
+import org.apache.logging.log4j.Logger;
+import org.apache.lucene.codecs.Codec;
+import org.apache.lucene.codecs.DocValuesFormat;
+import org.apache.lucene.codecs.FilterCodec;
+import org.apache.lucene.codecs.lucene99.Lucene99Codec;
+import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.index.codec.PerFieldMappingPostingFormatCodec;
+import org.opensearch.index.mapper.MapperService;
+
+/**
+ *  Extends the Codec to support new file formats for composite indices eg: star tree index
+ *  based on the mappings.
+ *
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public class Composite99Codec extends FilterCodec {
+    public static final String COMPOSITE_INDEX_CODEC_NAME = "Composite99Codec";
+    private final MapperService mapperService;
+
+    // needed for SPI - this is used in reader path
+    public Composite99Codec() {
+        this(COMPOSITE_INDEX_CODEC_NAME, new Lucene99Codec(), null);
+    }
+
+    public Composite99Codec(Lucene99Codec.Mode compressionMode, MapperService mapperService, Logger logger) {
+        this(COMPOSITE_INDEX_CODEC_NAME, new PerFieldMappingPostingFormatCodec(compressionMode, mapperService, logger), mapperService);
+    }
+
+    /**
+     * Sole constructor. When subclassing this codec, create a no-arg ctor and pass the delegate codec and a unique name to
+     * this ctor.
+     *
+     * @param name name of the codec
+     * @param delegate codec delegate
+     * @param mapperService mapper service instance
+     */
+    protected Composite99Codec(String name, Codec delegate, MapperService mapperService) {
+        super(name, delegate);
+        this.mapperService = mapperService;
+    }
+
+    @Override
+    public DocValuesFormat docValuesFormat() {
+        return new Composite99DocValuesFormat(mapperService);
+    }
+}

server/src/main/java/org/opensearch/index/codec/composite/Composite99DocValuesFormat.java

@@ -0,0 +1,64 @@
+/*
+ * 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.
+ */
+
+package org.opensearch.index.codec.composite;
+
+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;
+import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.index.mapper.MapperService;
+
+import java.io.IOException;
+
+/**
+ * DocValues format to handle composite indices
+ *
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public class Composite99DocValuesFormat extends DocValuesFormat {
+    /**
+     * Creates a new docvalues format.
+     *
+     * <p>The provided name will be written into the index segment in some configurations (such as
+     * when using {@code PerFieldDocValuesFormat}): in such configurations, for the segment to be read
+     * this class should be registered with Java's SPI mechanism (registered in META-INF/ of your jar
+     * file, etc).
+     */
+    private final DocValuesFormat delegate;
+    private final MapperService mapperService;
+
+    // needed for SPI
+    public Composite99DocValuesFormat() {
+        this(new Lucene90DocValuesFormat(), null);
+    }
+
+    public Composite99DocValuesFormat(MapperService mapperService) {
+        this(new Lucene90DocValuesFormat(), mapperService);
+    }
+
+    public Composite99DocValuesFormat(DocValuesFormat delegate, MapperService mapperService) {
+        super(delegate.getName());
+        this.delegate = delegate;
+        this.mapperService = mapperService;
+    }
+
+    @Override
+    public DocValuesConsumer fieldsConsumer(SegmentWriteState state) throws IOException {
+        return new Composite99DocValuesWriter(delegate.fieldsConsumer(state), state, mapperService);
+    }
+
+    @Override
+    public DocValuesProducer fieldsProducer(SegmentReadState state) throws IOException {
+        return new Composite99DocValuesReader(delegate.fieldsProducer(state), state);
+    }
+}

server/src/main/java/org/opensearch/index/codec/composite/Composite99DocValuesReader.java

@@ -0,0 +1,89 @@
+/*
+ * 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.
+ */
+
+package org.opensearch.index.codec.composite;
+
+import org.apache.lucene.codecs.DocValuesProducer;
+import org.apache.lucene.index.BinaryDocValues;
+import org.apache.lucene.index.FieldInfo;
+import org.apache.lucene.index.NumericDocValues;
+import org.apache.lucene.index.SegmentReadState;
+import org.apache.lucene.index.SortedDocValues;
+import org.apache.lucene.index.SortedNumericDocValues;
+import org.apache.lucene.index.SortedSetDocValues;
+import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.index.mapper.CompositeMappedFieldType;
+
+import java.io.IOException;
+import java.util.List;
+
+/**
+ * Reader for star tree index and star tree doc values from the segments
+ *
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public class Composite99DocValuesReader extends DocValuesProducer implements CompositeIndexReader {
+    private DocValuesProducer delegate;
+
+    public Composite99DocValuesReader(DocValuesProducer producer, SegmentReadState state) throws IOException {
+        this.delegate = producer;
+        // TODO : read star tree files
+    }
+
+    @Override
+    public NumericDocValues getNumeric(FieldInfo field) throws IOException {
+        return delegate.getNumeric(field);
+    }
+
+    @Override
+    public BinaryDocValues getBinary(FieldInfo field) throws IOException {
+        return delegate.getBinary(field);
+    }
+
+    @Override
+    public SortedDocValues getSorted(FieldInfo field) throws IOException {
+        return delegate.getSorted(field);
+    }
+
+    @Override
+    public SortedNumericDocValues getSortedNumeric(FieldInfo field) throws IOException {
+        return delegate.getSortedNumeric(field);
+    }
+
+    @Override
+    public SortedSetDocValues getSortedSet(FieldInfo field) throws IOException {
+        return delegate.getSortedSet(field);
+    }
+
+    @Override
+    public void checkIntegrity() throws IOException {
+        delegate.checkIntegrity();
+        // Todo : check integrity of composite index related [star tree] files
+    }
+
+    @Override
+    public void close() throws IOException {
+        delegate.close();
+        // Todo: close composite index related files [star tree] files
+    }
+
+    @Override
+    public List<String> getCompositeIndexFields() {
+        // todo : read from file formats and get the field names.
+        throw new UnsupportedOperationException();
+
+    }
+
+    @Override
+    public CompositeIndexValues getCompositeIndexValues(String field, CompositeMappedFieldType.CompositeFieldType fieldType)
+        throws IOException {
+        // TODO : read compositeIndexValues [starTreeValues] from star tree files
+        throw new UnsupportedOperationException();
+    }
+}

server/src/main/java/org/opensearch/index/codec/composite/Composite99DocValuesWriter.java

@@ -0,0 +1,114 @@
+/*
+ * 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.
+ */
+
+package org.opensearch.index.codec.composite;
+
+import org.apache.lucene.codecs.DocValuesConsumer;
+import org.apache.lucene.codecs.DocValuesProducer;
+import org.apache.lucene.index.FieldInfo;
+import org.apache.lucene.index.MergeState;
+import org.apache.lucene.index.SegmentWriteState;
+import org.opensearch.common.annotation.ExperimentalApi;
+import org.opensearch.index.mapper.CompositeMappedFieldType;
+import org.opensearch.index.mapper.MapperService;
+import org.opensearch.index.mapper.StarTreeMapper;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * This class write the star tree index and star tree doc values
+ * based on the doc values structures of the original index
+ *
+ * @opensearch.experimental
+ */
+@ExperimentalApi
+public class Composite99DocValuesWriter extends DocValuesConsumer {
+    private final DocValuesConsumer delegate;
+    private final SegmentWriteState state;
+    private final MapperService mapperService;
+    AtomicReference<MergeState> mergeState = new AtomicReference<>();
+    private final Set<CompositeMappedFieldType> compositeMappedFieldTypes;
+    private final Set<String> compositeFieldSet;
+
+    private final Map<String, DocValuesProducer> fieldProducerMap = new HashMap<>();
+
+    public Composite99DocValuesWriter(DocValuesConsumer delegate, SegmentWriteState segmentWriteState, MapperService mapperService) {
+
+        this.delegate = delegate;
+        this.state = segmentWriteState;
+        this.mapperService = mapperService;
+        this.compositeMappedFieldTypes = mapperService.getCompositeFieldTypes();
+        compositeFieldSet = new HashSet<>();
+        for (CompositeMappedFieldType type : compositeMappedFieldTypes) {
+            compositeFieldSet.addAll(type.fields());
+        }
+    }
+
+    @Override
+    public void addNumericField(FieldInfo field, DocValuesProducer valuesProducer) throws IOException {
+        delegate.addNumericField(field, valuesProducer);
+    }
+
+    @Override
+    public void addBinaryField(FieldInfo field, DocValuesProducer valuesProducer) throws IOException {
+        delegate.addBinaryField(field, valuesProducer);
+    }
+
+    @Override
+    public void addSortedField(FieldInfo field, DocValuesProducer valuesProducer) throws IOException {
+        delegate.addSortedField(field, valuesProducer);
+    }
+
+    @Override
+    public void addSortedNumericField(FieldInfo field, DocValuesProducer valuesProducer) throws IOException {
+        delegate.addSortedNumericField(field, valuesProducer);
+        // Perform this only during flush flow
+        if (mergeState.get() == null) {
+            createCompositeIndicesIfPossible(valuesProducer, field);
+        }
+    }
+
+    @Override
+    public void addSortedSetField(FieldInfo field, DocValuesProducer valuesProducer) throws IOException {
+        delegate.addSortedSetField(field, valuesProducer);
+    }
+
+    @Override
+    public void close() throws IOException {
+        delegate.close();
+    }
+
+    private void createCompositeIndicesIfPossible(DocValuesProducer valuesProducer, FieldInfo field) throws IOException {
+        if (compositeFieldSet.isEmpty()) return;
+        if (compositeFieldSet.contains(field.name)) {
+            fieldProducerMap.put(field.name, valuesProducer);
+            compositeFieldSet.remove(field.name);
+        }
+        // we have all the required fields to build composite fields
+        if (compositeFieldSet.isEmpty()) {
+            for (CompositeMappedFieldType mappedType : compositeMappedFieldTypes) {
+                if (mappedType instanceof StarTreeMapper.StarTreeFieldType) {
+                    // TODO : Call StarTree builder
+                }
+            }
+        }
+    }
+
+    @Override
+    public void merge(MergeState mergeState) throws IOException {
+        this.mergeState.compareAndSet(null, mergeState);
+        super.merge(mergeState);
+        // TODO : handle merge star tree
+        // mergeStarTreeFields(mergeState);
+    }
+}