Add isAsync() to SearcTask and eliminate code for async detection from TransportSearchAction (elastic#112311)

Author: smalyshev

server/src/main/java/org/elasticsearch/action/search/SearchTask.java

@@ -69,4 +69,11 @@ public Supplier<SearchResponseMerger> getSearchResponseMergerSupplier() {
     public void setSearchResponseMergerSupplier(Supplier<SearchResponseMerger> supplier) {
         this.searchResponseMergerSupplier = supplier;
     }
+
+    /**
+     * Is this async search?
+     */
+    public boolean isAsync() {
+        return false;
+    }
 }

server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java

@@ -369,7 +369,7 @@ void executeRequest(
             } else {
                 if ((listener instanceof TelemetryListener tl) && CCS_TELEMETRY_FEATURE_FLAG.isEnabled()) {
                     tl.setRemotes(resolvedIndices.getRemoteClusterIndices().size());
-                    if (isAsyncSearchTask(task)) {
+                    if (task.isAsync()) {
                         tl.setFeature(CCSUsageTelemetry.ASYNC_FEATURE);
                     }
                     String client = task.getHeader(Task.X_ELASTIC_PRODUCT_ORIGIN_HTTP_HEADER);
@@ -1514,34 +1514,6 @@ public SearchPhase newSearchPhase(
         }
     }
 
-    /**
-     * TransportSearchAction cannot access async-search code, so can't check whether this the Task
-     * is an instance of AsyncSearchTask, so this roundabout method is used
-     * @param searchTask SearchTask to analyze
-     * @return true if this is an async search task; false if a synchronous search task
-     */
-    private boolean isAsyncSearchTask(SearchTask searchTask) {
-        assert assertAsyncSearchTaskListener(searchTask) : "AsyncSearchTask SearchProgressListener is not one of the expected types";
-        // AsyncSearchTask will not return SearchProgressListener.NOOP, since it uses its own progress listener
-        // which delegates to CCSSingleCoordinatorSearchProgressListener when minimizing roundtrips.
-        // Only synchronous SearchTask uses SearchProgressListener.NOOP or CCSSingleCoordinatorSearchProgressListener directly
-        return searchTask.getProgressListener() != SearchProgressListener.NOOP
-            && searchTask.getProgressListener() instanceof CCSSingleCoordinatorSearchProgressListener == false;
-    }
-
-    /**
-     * @param searchTask SearchTask to analyze
-     * @return true if AsyncSearchTask still uses its own special listener, not one of the two that synchronous SearchTask uses
-     */
-    private boolean assertAsyncSearchTaskListener(SearchTask searchTask) {
-        if (searchTask.getClass().getSimpleName().contains("AsyncSearchTask")) {
-            SearchProgressListener progressListener = searchTask.getProgressListener();
-            return progressListener != SearchProgressListener.NOOP
-                && progressListener instanceof CCSSingleCoordinatorSearchProgressListener == false;
-        }
-        return true;
-    }
-
     private static void validateAndResolveWaitForCheckpoint(
         ClusterState clusterState,
         IndexNameExpressionResolver resolver,

x-pack/plugin/async-search/src/main/java/org/elasticsearch/xpack/search/AsyncSearchTask.java

@@ -545,4 +545,9 @@ public void onFailure(Exception exc) {
             executeCompletionListeners();
         }
     }
+
+    @Override
+    public boolean isAsync() {
+        return true;
+    }
 }