Convert parent-join mappers to parametrized form (#63878)

This converts the three parent-join mapper implementations to parametrized
form; MetaJoinFieldMapper and ParentIdFieldMapper have no builders or
merging logic as they are always created directly by the ParentJoinFieldMapper.

Relates to #62988

Author: romseygeek

modules/parent-join/src/main/java/org/elasticsearch/join/ParentJoinPlugin.java

@@ -63,6 +63,6 @@ public List<AggregationSpec> getAggregations() {
 
     @Override
     public Map<String, Mapper.TypeParser> getMappers() {
-        return Collections.singletonMap(ParentJoinFieldMapper.CONTENT_TYPE, new ParentJoinFieldMapper.TypeParser());
+        return Collections.singletonMap(ParentJoinFieldMapper.CONTENT_TYPE, ParentJoinFieldMapper.PARSER);
     }
 }

modules/parent-join/src/main/java/org/elasticsearch/join/mapper/MetaJoinFieldMapper.java

@@ -19,25 +19,19 @@
 
 package org.elasticsearch.join.mapper;
 
-import org.apache.lucene.document.FieldType;
-import org.apache.lucene.index.IndexOptions;
 import org.apache.lucene.search.Query;
-import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.index.fielddata.IndexFieldData;
-import org.elasticsearch.index.fielddata.plain.SortedSetOrdinalsIndexFieldData;
-import org.elasticsearch.index.mapper.FieldMapper;
 import org.elasticsearch.index.mapper.MapperService;
+import org.elasticsearch.index.mapper.MetadataFieldMapper;
 import org.elasticsearch.index.mapper.ParseContext;
 import org.elasticsearch.index.mapper.StringFieldType;
 import org.elasticsearch.index.mapper.TextSearchInfo;
 import org.elasticsearch.index.mapper.ValueFetcher;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
 import org.elasticsearch.search.lookup.SearchLookup;
 
 import java.io.IOException;
 import java.util.Collections;
-import java.util.List;
 import java.util.function.Supplier;
 
 /**
@@ -47,35 +41,11 @@
  * This class is also used to quickly retrieve the parent-join field defined in a mapping without
  * specifying the name of the field.
  */
-public class MetaJoinFieldMapper extends FieldMapper {
+public class MetaJoinFieldMapper extends MetadataFieldMapper {
+
     static final String NAME = "_parent_join";
     static final String CONTENT_TYPE = "parent_join";
 
-    static class Defaults {
-        public static final FieldType FIELD_TYPE = new FieldType();
-
-        static {
-            FIELD_TYPE.setStored(false);
-            FIELD_TYPE.setIndexOptions(IndexOptions.NONE);
-            FIELD_TYPE.freeze();
-        }
-    }
-
-    static class Builder extends FieldMapper.Builder {
-
-        final String joinField;
-
-        Builder(String joinField) {
-            super(NAME, Defaults.FIELD_TYPE);
-            this.joinField = joinField;
-        }
-
-        @Override
-        public MetaJoinFieldMapper build(BuilderContext context) {
-            return new MetaJoinFieldMapper(name, joinField);
-        }
-    }
-
     public static class MetaJoinFieldType extends StringFieldType {
 
         private final String joinField;
@@ -92,22 +62,17 @@ public String typeName() {
 
         @Override
         public IndexFieldData.Builder fielddataBuilder(String fullyQualifiedIndexName, Supplier<SearchLookup> searchLookup) {
-            failIfNoDocValues();
-            return new SortedSetOrdinalsIndexFieldData.Builder(name(), CoreValuesSourceType.BYTES);
+            throw new UnsupportedOperationException("Cannot load field data for metadata field [" + NAME + "]");
         }
 
         @Override
         public ValueFetcher valueFetcher(MapperService mapperService, SearchLookup searchLookup, String format) {
-            throw new UnsupportedOperationException("Cannot fetch values for metadata field [" + typeName() + "].");
+            throw new UnsupportedOperationException("Cannot fetch values for metadata field [" + NAME + "].");
         }
 
         @Override
         public Object valueForDisplay(Object value) {
-            if (value == null) {
-                return null;
-            }
-            BytesRef binaryValue = (BytesRef) value;
-            return binaryValue.utf8ToString();
+            throw new UnsupportedOperationException();
         }
 
         public String getJoinField() {
@@ -120,8 +85,8 @@ public Query existsQuery(QueryShardContext context) {
         }
     }
 
-    MetaJoinFieldMapper(String name, String joinField) {
-        super(name, Defaults.FIELD_TYPE, new MetaJoinFieldType(joinField), MultiFields.empty(), CopyTo.empty());
+    MetaJoinFieldMapper(String joinField) {
+        super(new MetaJoinFieldType(joinField));
     }
 
     @Override
@@ -134,10 +99,6 @@ protected MetaJoinFieldMapper clone() {
         return (MetaJoinFieldMapper) super.clone();
     }
 
-    @Override
-    protected void mergeOptions(FieldMapper other, List<String> conflicts) {
-    }
-
     @Override
     protected void parseCreateField(ParseContext context) throws IOException {
         throw new IllegalStateException("Should never be called");

modules/parent-join/src/main/java/org/elasticsearch/join/mapper/ParentIdFieldMapper.java

@@ -27,9 +27,8 @@
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.index.fielddata.IndexFieldData;
 import org.elasticsearch.index.fielddata.plain.SortedSetOrdinalsIndexFieldData;
-import org.elasticsearch.index.mapper.FieldMapper;
-import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.MapperService;
+import org.elasticsearch.index.mapper.ParametrizedFieldMapper;
 import org.elasticsearch.index.mapper.ParseContext;
 import org.elasticsearch.index.mapper.StringFieldType;
 import org.elasticsearch.index.mapper.TextSearchInfo;
@@ -38,14 +37,13 @@
 import org.elasticsearch.search.lookup.SearchLookup;
 
 import java.util.Collections;
-import java.util.List;
 import java.util.function.Supplier;
 
 /**
  * A field mapper used internally by the {@link ParentJoinFieldMapper} to index
  * the value that link documents in the index (parent _id or _id if the document is a parent).
  */
-public final class ParentIdFieldMapper extends FieldMapper {
+public final class ParentIdFieldMapper extends ParametrizedFieldMapper {
     static final String CONTENT_TYPE = "parent";
 
     static class Defaults {
@@ -59,24 +57,6 @@ static class Defaults {
         }
     }
 
-    static class Builder extends FieldMapper.Builder {
-
-        Builder(String name) {
-            super(name, Defaults.FIELD_TYPE);
-        }
-
-        public Builder eagerGlobalOrdinals(boolean eagerGlobalOrdinals) {
-            this.eagerGlobalOrdinals = eagerGlobalOrdinals;
-            return this;
-        }
-
-        @Override
-        public ParentIdFieldMapper build(BuilderContext context) {
-            return new ParentIdFieldMapper(name, fieldType,
-                new ParentIdFieldType(buildFullName(context), eagerGlobalOrdinals));
-        }
-    }
-
     public static final class ParentIdFieldType extends StringFieldType {
         public ParentIdFieldType(String name, boolean eagerGlobalOrdinals) {
             super(name, true, false, true, TextSearchInfo.SIMPLE_MATCH_ONLY, Collections.emptyMap());
@@ -110,10 +90,8 @@ public Object valueForDisplay(Object value) {
         }
     }
 
-    protected ParentIdFieldMapper(String simpleName,
-                                  FieldType fieldType,
-                                  MappedFieldType mappedFieldType) {
-        super(simpleName, fieldType, mappedFieldType, MultiFields.empty(), CopyTo.empty());
+    protected ParentIdFieldMapper(String name, boolean eagerGlobalOrdinals) {
+        super(name, new ParentIdFieldType(name, eagerGlobalOrdinals), MultiFields.empty(), CopyTo.empty());
     }
 
     @Override
@@ -128,18 +106,18 @@ protected void parseCreateField(ParseContext context) {
         }
         String refId = (String) context.externalValue();
         BytesRef binaryValue = new BytesRef(refId);
-        Field field = new Field(fieldType().name(), binaryValue, fieldType);
+        Field field = new Field(fieldType().name(), binaryValue, Defaults.FIELD_TYPE);
         context.doc().add(field);
         context.doc().add(new SortedDocValuesField(fieldType().name(), binaryValue));
     }
 
     @Override
-    protected void mergeOptions(FieldMapper other, List<String> conflicts) {
-
+    protected String contentType() {
+        return CONTENT_TYPE;
     }
 
     @Override
-    protected String contentType() {
-        return CONTENT_TYPE;
+    public Builder getMergeBuilder() {
+        return null;    // always constructed by ParentJoinFieldMapper, not through type parsers
     }
 }