Introduce incremental reduction of TopDocs (#23946)

This commit adds support for incremental top N reduction if the number of
expected shards in the search request is high enough. The changes here
also clean up more code in SearchPhaseController to make the separation
between values that are the same on each search result and values that
are per response. The reduced search phase result doesn't hold an arbitrary
result to obtain values like `from`, `size` or sort values which is now
cleanly encapsulated.

1 files changed, 15 insertions, 4 deletions

diff --git a/core/src/test/java/org/elasticsearch/search/SearchServiceTests.java b/core/src/test/java/org/elasticsearch/search/SearchServiceTests.java
index f3ff6be1cc..6fc795a882 100644
--- a/core/src/test/java/org/elasticsearch/search/SearchServiceTests.java
+++ b/core/src/test/java/org/elasticsearch/search/SearchServiceTests.java
@@ -223,8 +223,13 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
                 new AliasFilter(null, Strings.EMPTY_ARRAY),
                 1.0f),
             null);
-        // the search context should inherit the default timeout
-        assertThat(contextWithDefaultTimeout.timeout(), equalTo(TimeValue.timeValueSeconds(5)));
+        try {
+            // the search context should inherit the default timeout
+            assertThat(contextWithDefaultTimeout.timeout(), equalTo(TimeValue.timeValueSeconds(5)));
+        } finally {
+            contextWithDefaultTimeout.decRef();
+            service.freeContext(contextWithDefaultTimeout.id());
+        }
 
         final long seconds = randomIntBetween(6, 10);
         final SearchContext context = service.createContext(
@@ -238,8 +243,14 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
                 new AliasFilter(null, Strings.EMPTY_ARRAY),
                 1.0f),
             null);
-        // the search context should inherit the query timeout
-        assertThat(context.timeout(), equalTo(TimeValue.timeValueSeconds(seconds)));
+        try {
+            // the search context should inherit the query timeout
+            assertThat(context.timeout(), equalTo(TimeValue.timeValueSeconds(seconds)));
+        } finally {
+            context.decRef();
+            service.freeContext(context.id());
+        }
+
     }
 
     public static class FailOnRewriteQueryPlugin extends Plugin implements SearchPlugin {