Tidy up the downsample package (#93912)

* Removed used fields/parameters
* Made field final
* Removed unchecked warning

x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/AggregateMetricFieldValueFetcher.java

@@ -17,7 +17,7 @@ import java.util.List;
 
 public class AggregateMetricFieldValueFetcher extends FieldValueFetcher {
 
-    private AggregateDoubleMetricFieldType aggMetricFieldType;
+    private final AggregateDoubleMetricFieldType aggMetricFieldType;
 
     private final AbstractDownsampleFieldProducer rollupFieldProducer;
 

x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/RollupShardIndexer.java

@@ -67,7 +67,7 @@ import static org.elasticsearch.core.Strings.format;
 /**
  * An indexer for downsampling that iterates documents collected by {@link TimeSeriesIndexSearcher},
  * computes the rollup buckets and stores the buckets in the downsampled index.
- *
+ * <p>
  * The documents collected by the {@link TimeSeriesIndexSearcher} are expected to be sorted
  * by _tsid in ascending order and @timestamp in descending order.
  */
@@ -78,18 +78,12 @@ class RollupShardIndexer {
 
     private final IndexShard indexShard;
     private final Client client;
-    private final DownsampleConfig config;
     private final String rollupIndex;
-
     private final Engine.Searcher searcher;
     private final SearchExecutionContext searchExecutionContext;
     private final MappedFieldType timestampField;
     private final DocValueFormat timestampFormat;
     private final Rounding.Prepared rounding;
-
-    private final String[] dimensionFields;
-    private final String[] metricFields;
-    private final String[] labelFields;
     private final List<FieldValueFetcher> fieldValueFetchers;
     private final RollupShardTask task;
     private volatile boolean abort = false;
@@ -101,18 +95,13 @@ class RollupShardIndexer {
         ShardId shardId,
         String rollupIndex,
         DownsampleConfig config,
-        String[] dimensionFields,
         String[] metricFields,
         String[] labelFields
     ) {
         this.task = task;
         this.client = client;
         this.indexShard = indexService.getShard(shardId.id());
-        this.config = config;
         this.rollupIndex = rollupIndex;
-        this.dimensionFields = dimensionFields;
-        this.metricFields = metricFields;
-        this.labelFields = labelFields;
         this.searcher = indexShard.acquireSearcher("downsampling");
         Closeable toClose = searcher;
         try {
@@ -142,7 +131,7 @@ class RollupShardIndexer {
         long startTime = System.currentTimeMillis();
         BulkProcessor bulkProcessor = createBulkProcessor();
         try (searcher; bulkProcessor) {
-            final TimeSeriesIndexSearcher timeSeriesSearcher = new TimeSeriesIndexSearcher(searcher, List.of(() -> { checkCancelled(); }));
+            final TimeSeriesIndexSearcher timeSeriesSearcher = new TimeSeriesIndexSearcher(searcher, List.of(this::checkCancelled));
             TimeSeriesBucketCollector bucketCollector = new TimeSeriesBucketCollector(bulkProcessor);
             bucketCollector.preCollection();
             timeSeriesSearcher.search(new MatchAllDocsQuery(), bucketCollector);
@@ -198,9 +187,7 @@ class RollupShardIndexer {
             public void afterBulk(long executionId, BulkRequest request, BulkResponse response) {
                 task.addNumIndexed(request.numberOfActions());
                 if (response.hasFailures()) {
-                    List<BulkItemResponse> failedItems = Arrays.stream(response.getItems())
-                        .filter(BulkItemResponse::isFailed)
-                        .collect(Collectors.toList());
+                    List<BulkItemResponse> failedItems = Arrays.stream(response.getItems()).filter(BulkItemResponse::isFailed).toList();
                     task.addNumFailed(failedItems.size());
 
                     Map<String, String> failures = failedItems.stream()
@@ -393,16 +380,16 @@ class RollupShardIndexer {
         /**
          * tsid changed, reset tsid and timestamp
          */
-        public RollupBucketBuilder resetTsid(BytesRef tsid, int tsidOrd, long timestamp) {
+        public void resetTsid(BytesRef tsid, int tsidOrd, long timestamp) {
             this.tsid = BytesRef.deepCopyOf(tsid);
             this.tsidOrd = tsidOrd;
-            return resetTimestamp(timestamp);
+            resetTimestamp(timestamp);
         }
 
         /**
          * timestamp change, reset builder
          */
-        public RollupBucketBuilder resetTimestamp(long timestamp) {
+        public void resetTimestamp(long timestamp) {
             this.timestamp = timestamp;
             this.docCount = 0;
             this.rollupFieldProducers.forEach(AbstractDownsampleFieldProducer::reset);
@@ -413,7 +400,6 @@ class RollupShardIndexer {
                     timestampFormat.format(timestamp)
                 );
             }
-            return this;
         }
 
         public void collectDocCount(int docCount) {
@@ -431,11 +417,10 @@ class RollupShardIndexer {
             builder.field(timestampField.name(), timestampFormat.format(timestamp));
             builder.field(DocCountFieldMapper.NAME, docCount);
             // Extract dimension values from _tsid field, so we avoid loading them from doc_values
-            @SuppressWarnings("unchecked")
-            Map<String, Object> dimensions = (Map<String, Object>) DocValueFormat.TIME_SERIES_ID.format(tsid);
-            for (Map.Entry<String, Object> e : dimensions.entrySet()) {
+            Map<?, ?> dimensions = (Map<?, ?>) DocValueFormat.TIME_SERIES_ID.format(tsid);
+            for (Map.Entry<?, ?> e : dimensions.entrySet()) {
                 assert e.getValue() != null;
-                builder.field(e.getKey(), e.getValue());
+                builder.field((String) e.getKey(), e.getValue());
             }
 
             /*

x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportDownsampleIndexerAction.java

@@ -142,7 +142,6 @@ public class TransportDownsampleIndexerAction extends TransportBroadcastAction<
             request.shardId(),
             request.getRollupIndex(),
             request.getRollupConfig(),
-            request.getDimensionFields(),
             request.getMetricFields(),
             request.getLabelFields()
         );

x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/downsample/DownsampleActionSingleNodeTests.java

@@ -616,7 +616,6 @@ public class DownsampleActionSingleNodeTests extends ESSingleNodeTestCase {
             shard.shardId(),
             rollupIndex,
             config,
-            new String[] { FIELD_DIMENSION_1, FIELD_DIMENSION_2 },
             new String[] { FIELD_NUMERIC_1, FIELD_NUMERIC_2 },
             new String[] {}
         );