ValuesSource refactoring: Wire up Avg aggregation

server/src/main/java/org/elasticsearch/search/SearchModule.java

@@ -339,7 +339,8 @@ public Map<String, Highlighter> getHighlighters() {
 
     private void registerAggregations(List<SearchPlugin> plugins) {
         registerAggregation(new AggregationSpec(AvgAggregationBuilder.NAME, AvgAggregationBuilder::new, AvgAggregationBuilder::parse)
-                .addResultReader(InternalAvg::new));
+            .addResultReader(InternalAvg::new)
+            .setAggregatorRegistrar(AvgAggregationBuilder::registerAggregators));
         registerAggregation(new AggregationSpec(WeightedAvgAggregationBuilder.NAME, WeightedAvgAggregationBuilder::new,
             WeightedAvgAggregationBuilder::parse).addResultReader(InternalWeightedAvg::new));
         registerAggregation(new AggregationSpec(SumAggregationBuilder.NAME, SumAggregationBuilder::new, SumAggregationBuilder::parse)

server/src/main/java/org/elasticsearch/search/aggregations/metrics/AvgAggregationBuilder.java

@@ -33,6 +33,7 @@
 import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
 import org.elasticsearch.search.aggregations.support.ValuesSourceParserHelper;
 import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
+import org.elasticsearch.search.aggregations.support.ValuesSourceRegistry;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 
 import java.io.IOException;
@@ -50,6 +51,10 @@ public static AggregationBuilder parse(String aggregationName, XContentParser pa
         return PARSER.parse(parser, aggregationName);
     }
 
+    public static void registerAggregators(ValuesSourceRegistry valuesSourceRegistry) {
+        AvgAggregatorFactory.registerAggregators(valuesSourceRegistry);
+    }
+
     public AvgAggregationBuilder(String name) {
         super(name);
     }

server/src/main/java/org/elasticsearch/search/aggregations/metrics/AvgAggregatorFactory.java

@@ -20,15 +20,19 @@
 package org.elasticsearch.search.aggregations.metrics;
 
 import org.elasticsearch.index.query.QueryShardContext;
+import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.AggregationExecutionException;
 import org.elasticsearch.search.aggregations.Aggregator;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
 import org.elasticsearch.search.aggregations.AggregatorFactory;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+import org.elasticsearch.search.aggregations.support.AggregatorSupplier;
+import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
 import org.elasticsearch.search.aggregations.support.ValuesSource.Numeric;
 import org.elasticsearch.search.aggregations.support.ValuesSourceAggregatorFactory;
 import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
+import org.elasticsearch.search.aggregations.support.ValuesSourceRegistry;
 import org.elasticsearch.search.internal.SearchContext;
 
 import java.io.IOException;
@@ -43,6 +47,22 @@ class AvgAggregatorFactory extends ValuesSourceAggregatorFactory {
         super(name, config, queryShardContext, parent, subFactoriesBuilder, metaData);
     }
 
+    static void registerAggregators(ValuesSourceRegistry valuesSourceRegistry) {
+        valuesSourceRegistry.register(AvgAggregationBuilder.NAME,
+            List.of(CoreValuesSourceType.NUMERIC, CoreValuesSourceType.DATE, CoreValuesSourceType.BOOLEAN),
+            new MetricAggregatorSupplier() {
+                @Override
+                public Aggregator build(String name,
+                                        ValuesSource valuesSource,
+                                        DocValueFormat formatter,
+                                        SearchContext context,
+                                        Aggregator parent,
+                                        List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) throws IOException {
+                    return new AvgAggregator(name, (Numeric) valuesSource, formatter, context, parent, pipelineAggregators, metaData);
+                }
+            });
+    }
+
     @Override
     protected Aggregator createUnmapped(SearchContext searchContext,
                                             Aggregator parent,
@@ -58,11 +78,14 @@ protected Aggregator doCreateInternal(ValuesSource valuesSource,
                                             boolean collectsFromSingleBucket,
                                             List<PipelineAggregator> pipelineAggregators,
                                             Map<String, Object> metaData) throws IOException {
+        AggregatorSupplier aggregatorSupplier = queryShardContext.getValuesSourceRegistry().getAggregator(config.valueSourceType(),
+            AvgAggregationBuilder.NAME);
 
-        if (valuesSource instanceof Numeric == false) {
-            throw new AggregationExecutionException("ValuesSource type " + valuesSource.toString() + "is not supported for aggregation " +
-                this.name());
+        if (aggregatorSupplier instanceof MetricAggregatorSupplier == false) {
+            throw new AggregationExecutionException("Registry miss-match - expected MetricAggregatorSupplier, found [" +
+                aggregatorSupplier.getClass().toString() + "]");
         }
-        return new AvgAggregator(name, (Numeric) valuesSource, config.format(), searchContext, parent, pipelineAggregators, metaData);
+        return ((MetricAggregatorSupplier) aggregatorSupplier).build(name, valuesSource, config.format(), searchContext, parent,
+            pipelineAggregators, metaData);
     }
 }