Minimize the scope of retuned dto on a per shard basis

Author: drempapis

server/src/main/java/org/elasticsearch/index/search/stats/ShardSearchLoadRateService.java

@@ -12,41 +12,22 @@
 /**
  * Service interface for estimating the search load rate of a shard using provided search statistics.
  * <p>
- * Implementations may apply various heuristics or models, such as exponentially weighted moving averages,
+ * Implementations may apply various heuristics or models, such as exponentially weighted moving rate,
  * to track and estimate the current load on a shard based on its search activity.
  */
 public interface ShardSearchLoadRateService {
 
     /**
-     * A no-op implementation of {@code ShardSearchLoadRateService} that always returns {@link SearchLoadRate#NO_OP}.
+     * A no-op implementation of {@code ShardSearchLoadRateService} that always returns  {@code 0.0}
      * This can be used as a fallback or default when no actual load tracking is required.
      */
-    ShardSearchLoadRateService NOOP = (stats) -> SearchLoadRate.NO_OP;
+    ShardSearchLoadRateService NOOP = (stats) -> 0.0;
 
     /**
      * Computes the search load rate based on the provided shard-level search statistics.
      *
      * @param stats the search statistics for the shard, typically including metrics like query count, latency, etc.
-     * @return the {@link SearchLoadRate} representing the current estimated load on the shard
+     * @return the {@code double} representing the calculated EWMR on the shard
      */
-    SearchLoadRate getSearchLoadRate(SearchStats.Stats stats);
-
-    /**
-     * Represents the search load rate as computed over time using an exponentially weighted moving average (EWM).
-     * <p>
-     * This record captures the timing of the last update, the delta since the last observation,
-     * and the computed rate itself.
-     *
-     * @param lastTrackedTime the timestamp (e.g., in milliseconds or nanoseconds) of the last update
-     * @param delta the elapsed time since the previous update
-     * @param ewmRate the current exponentially weighted moving average rate
-     */
-    record SearchLoadRate(long lastTrackedTime, long delta, double ewmRate) {
-
-        /**
-         * A static no-op instance representing a default or zeroed state of {@code SearchLoadRate}.
-         * All numeric values are initialized to zero.
-         */
-        public static final SearchLoadRate NO_OP = new SearchLoadRate(0, 0, 0.0);
-    }
+    double getSearchLoadRate(SearchStats.Stats stats);
 }

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -1424,7 +1424,7 @@ public SearchStats searchStats(String... groups) {
     /**
      * Returns the search load rate stats for this shard.
      */
-    public ShardSearchLoadRateService.SearchLoadRate getSearchLoadRate() {
+    public double getSearchLoadRate() {
         return shardSearchLoadRateService.getSearchLoadRate(searchStats.stats().getTotal());
     }