Return true for can_match on idle search shards

server/src/main/java/org/elasticsearch/search/SearchService.java

@@ -1135,11 +1135,9 @@ public CanMatchResponse canMatch(ShardSearchRequest request) throws IOException
     }
 
     public void canMatch(ShardSearchRequest request, ActionListener<CanMatchResponse> listener) {
-        try {
-            listener.onResponse(canMatch(request));
-        } catch (IOException e) {
-            listener.onFailure(e);
-        }
+        IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
+        IndexShard indexShard = indexService.getShard(request.shardId().getId());
+        indexShard.awaitShardSearchActive(ignored -> ActionListener.completeWith(listener, () -> canMatch(request)));
     }
 
     /**

server/src/test/java/org/elasticsearch/action/search/TransportSearchIT.java

@@ -21,12 +21,19 @@
 
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.index.query.RangeQueryBuilder;
+import org.elasticsearch.index.shard.IndexShard;
+import org.elasticsearch.index.shard.IndexShardTestCase;
+import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.test.ESIntegTestCase;
 
 import java.util.Collections;
 
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
 
 public class TransportSearchIT extends ESIntegTestCase {
 
@@ -69,4 +76,33 @@ public void testShardCountLimit() throws Exception {
                             TransportSearchAction.SHARD_COUNT_LIMIT_SETTING.getKey(), null)));
         }
     }
+
+    public void testSearchIdle() throws Exception {
+        int numOfReplicas = randomIntBetween(0, 1);
+        internalCluster().ensureAtLeastNumDataNodes(numOfReplicas + 1);
+        final Settings.Builder settings = Settings.builder()
+            .put(IndexMetadata.SETTING_NUMBER_OF_SHARDS, randomIntBetween(1, 5))
+            .put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, numOfReplicas)
+            .put(IndexSettings.INDEX_SEARCH_IDLE_AFTER.getKey(), TimeValue.timeValueMillis(randomIntBetween(50, 500)));
+        assertAcked(prepareCreate("test").setSettings(settings)
+            .setMapping("{\"properties\":{\"created_date\":{\"type\": \"date\", \"format\": \"yyyy-MM-dd\"}}}"));
+        ensureGreen("test");
+        assertBusy(() -> {
+            for (String node : internalCluster().nodesInclude("test")) {
+                final IndicesService indicesService = internalCluster().getInstance(IndicesService.class, node);
+                for (IndexShard indexShard : indicesService.indexServiceSafe(resolveIndex("test"))) {
+                    IndexShardTestCase.isSearchIdle(indexShard);
+                }
+            }
+        });
+        client().prepareIndex("test").setId("1").setSource("created_date", "2020-01-01").get();
+        client().prepareIndex("test").setId("2").setSource("created_date", "2020-01-02").get();
+        client().prepareIndex("test").setId("3").setSource("created_date", "2020-01-03").get();
+        assertBusy(() -> {
+            SearchResponse resp = client().prepareSearch("test")
+                .setQuery(new RangeQueryBuilder("created_date").gte("2020-01-02").lte("2020-01-03"))
+                .setPreFilterShardSize(randomIntBetween(1, 3)).get();
+            assertThat(resp.getHits().getTotalHits().value, equalTo(2L));
+        });
+    }
 }

test/framework/src/main/java/org/elasticsearch/index/shard/IndexShardTestCase.java

@@ -877,4 +877,8 @@ public static Engine.Warmer createTestWarmer(IndexSettings indexSettings) {
             }
         };
     }
+
+    public static boolean isSearchIdle(IndexShard shard) {
+        return shard.isSearchIdle();
+    }
 }