A simple metric capturing mechanism to expose metrics to queries

Author: henningandersen

server/src/main/java/org/elasticsearch/index/IndexService.java

@@ -174,7 +174,7 @@ public class IndexService extends AbstractIndexComponent implements IndicesClust
     private final IndexingStatsSettings indexingStatsSettings;
     private final SearchStatsSettings searchStatsSettings;
     private final MergeMetrics mergeMetrics;
-    private MetricHolder<StoreMetrics> metricHandler;
+    private final MetricHolder<StoreMetrics> metricHolder;
 
     @SuppressWarnings("this-escape")
     public IndexService(
@@ -214,7 +214,7 @@ public IndexService(
         IndexingStatsSettings indexingStatsSettings,
         SearchStatsSettings searchStatsSettings,
         MergeMetrics mergeMetrics,
-        MetricHolder<StoreMetrics> metricHandler
+        MetricHolder<StoreMetrics> metricHolder
     ) {
         super(indexSettings);
         assert indexCreationContext != IndexCreationContext.RELOAD_ANALYZERS
@@ -301,7 +301,7 @@ public IndexService(
         this.indexingStatsSettings = indexingStatsSettings;
         this.searchStatsSettings = searchStatsSettings;
         this.mergeMetrics = mergeMetrics;
-        this.metricHandler = metricHandler;
+        this.metricHolder = metricHolder;
         updateFsyncTaskIfNecessary();
     }
 
@@ -565,7 +565,7 @@ public synchronized IndexShard createShard(
                 lock,
                 new StoreCloseListener(shardId, () -> eventListener.onStoreClosed(shardId)),
                 this.indexSettings.getIndexSortConfig().hasIndexSort(),
-                metricHandler
+                metricHolder
             );
             eventListener.onStoreCreated(shardId);
             indexShard = new IndexShard(

server/src/test/java/org/elasticsearch/index/IndexModuleTests.java

@@ -82,7 +82,6 @@
 import org.elasticsearch.index.similarity.NonNegativeScoresSimilarity;
 import org.elasticsearch.index.similarity.SimilarityService;
 import org.elasticsearch.index.store.FsDirectoryFactory;
-import org.elasticsearch.index.store.MetricHolder;
 import org.elasticsearch.index.store.Store;
 import org.elasticsearch.index.store.StoreMetrics;
 import org.elasticsearch.indices.IndicesModule;