Update BucketUtils#suggestShardSideQueueSize signature (#33210)

`BucketUtils#suggestShardSideQueueSize` used to calculate the shard_size based on the number of shards. It returns now a different value only based on whether we are querying a single shard or multiple shards. This commit replaces the numberOfShards argument with a boolean that tells whether we are querying a single shard or not.

server/src/main/java/org/elasticsearch/search/aggregations/bucket/BucketUtils.java

@@ -31,27 +31,21 @@ public final class BucketUtils {
      * 
      * @param finalSize
      *            The number of terms required in the final reduce phase.
-     * @param numberOfShards
+     * @param singleShard
-     *            The number of shards being queried.
+     *            whether a single shard is being queried, or multiple shards
      * @return A suggested default for the size of any shard-side PriorityQueues
      */
-    public static int suggestShardSideQueueSize(int finalSize, int numberOfShards) {
+    public static int suggestShardSideQueueSize(int finalSize, boolean singleShard) {
         if (finalSize < 1) {
             throw new IllegalArgumentException("size must be positive, got " + finalSize);
         }
-        if (numberOfShards < 1) {
+        if (singleShard) {
-            throw new IllegalArgumentException("number of shards must be positive, got " + numberOfShards);
-        }
-
-        if (numberOfShards == 1) {
             // In the case of a single shard, we do not need to over-request
             return finalSize;
         }
-
         // Request 50% more buckets on the shards in order to improve accuracy
         // as well as a small constant that should help with small values of 'size'
         final long shardSampleSize = (long) (finalSize * 1.5 + 10);
         return (int) Math.min(Integer.MAX_VALUE, shardSampleSize);
     }
-    
 }

server/src/main/java/org/elasticsearch/search/aggregations/bucket/geogrid/GeoGridAggregationBuilder.java

@@ -157,7 +157,7 @@ public class GeoGridAggregationBuilder extends ValuesSourceAggregationBuilder<Va
         if (shardSize < 0) {
             // Use default heuristic to avoid any wrong-ranking caused by
             // distributed counting
-            shardSize = BucketUtils.suggestShardSideQueueSize(requiredSize, context.numberOfShards());
+            shardSize = BucketUtils.suggestShardSideQueueSize(requiredSize, context.numberOfShards() == 1);
         }
 
         if (requiredSize <= 0 || shardSize <= 0) {

server/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/SignificantTermsAggregatorFactory.java

@@ -195,7 +195,7 @@ public class SignificantTermsAggregatorFactory extends ValuesSourceAggregatorFac
             // such are impossible to differentiate from non-significant terms
             // at that early stage.
             bucketCountThresholds.setShardSize(2 * BucketUtils.suggestShardSideQueueSize(bucketCountThresholds.getRequiredSize(),
-                    context.numberOfShards()));
+                    context.numberOfShards() == 1));
         }
 
         if (valuesSource instanceof ValuesSource.Bytes) {

server/src/main/java/org/elasticsearch/search/aggregations/bucket/significant/SignificantTextAggregatorFactory.java

@@ -176,7 +176,7 @@ public class SignificantTextAggregatorFactory extends AggregatorFactory<Signific
             // such are impossible to differentiate from non-significant terms
             // at that early stage.
             bucketCountThresholds.setShardSize(2 * BucketUtils.suggestShardSideQueueSize(bucketCountThresholds.getRequiredSize(),
-                    context.numberOfShards()));
+                    context.numberOfShards() == 1));
         }
 
 //        TODO - need to check with mapping that this is indeed a text field....

server/src/main/java/org/elasticsearch/search/aggregations/bucket/terms/TermsAggregatorFactory.java

@@ -122,7 +122,7 @@ public class TermsAggregatorFactory extends ValuesSourceAggregatorFactory<Values
             // heuristic to avoid any wrong-ranking caused by distributed
             // counting
             bucketCountThresholds.setShardSize(BucketUtils.suggestShardSideQueueSize(bucketCountThresholds.getRequiredSize(),
-                    context.numberOfShards()));
+                    context.numberOfShards() == 1));
         }
         bucketCountThresholds.ensureValidity();
         if (valuesSource instanceof ValuesSource.Bytes) {

server/src/test/java/org/elasticsearch/search/aggregations/bucket/BucketUtilsTests.java

@@ -27,18 +27,14 @@ public class BucketUtilsTests extends ESTestCase {
 
     public void testBadInput() {
         IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
-                () -> BucketUtils.suggestShardSideQueueSize(0, 10));
+                () -> BucketUtils.suggestShardSideQueueSize(0, randomBoolean()));
         assertEquals(e.getMessage(), "size must be positive, got 0");
-
-        e = expectThrows(IllegalArgumentException.class,
-                () -> BucketUtils.suggestShardSideQueueSize(10, 0));
-        assertEquals(e.getMessage(), "number of shards must be positive, got 0");
     }
 
     public void testOptimizesSingleShard() {
         for (int iter = 0; iter < 10; ++iter) {
             final int size = randomIntBetween(1, Integer.MAX_VALUE);
-            assertEquals(size, BucketUtils.suggestShardSideQueueSize( size, 1));
+            assertEquals(size, BucketUtils.suggestShardSideQueueSize( size, true));
         }
     }
 
@@ -46,7 +42,7 @@ public class BucketUtilsTests extends ESTestCase {
         for (int iter = 0; iter < 10; ++iter) {
             final int size = Integer.MAX_VALUE - randomInt(10);
             final int numberOfShards = randomIntBetween(1, 10);
-            final int shardSize = BucketUtils.suggestShardSideQueueSize( size, numberOfShards);
+            final int shardSize = BucketUtils.suggestShardSideQueueSize( size, numberOfShards == 1);
             assertThat(shardSize, greaterThanOrEqualTo(shardSize));
         }
     }
@@ -55,7 +51,7 @@ public class BucketUtilsTests extends ESTestCase {
         for (int iter = 0; iter < 10; ++iter) {
             final int size = randomIntBetween(1, Integer.MAX_VALUE);
             final int numberOfShards = randomIntBetween(1, 10);
-            final int shardSize = BucketUtils.suggestShardSideQueueSize( size, numberOfShards);
+            final int shardSize = BucketUtils.suggestShardSideQueueSize( size, numberOfShards == 1);
             assertThat(shardSize, greaterThanOrEqualTo(size));
         }
     }