Adjust unpromotable shard refresh request validation to allow RefreshResult.NO_REFRESH

docs/changelog/129176.yaml

@@ -0,0 +1,6 @@
+pr: 129176
+summary: Adjust unpromotable shard refresh request validation to allow `RefreshResult.NO_REFRESH`
+area: Searchable Snapshots
+type: bug
+issues:
+ - 129036

server/src/main/java/org/elasticsearch/action/admin/indices/refresh/TransportShardRefreshAction.java

@@ -23,7 +23,6 @@
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.injection.guice.Inject;
@@ -127,10 +126,7 @@ public void onPrimaryOperationComplete(
             ActionListener<Void> listener
         ) {
             var primaryTerm = replicaRequest.primaryRefreshResult.primaryTerm();
-            assert Engine.UNKNOWN_PRIMARY_TERM < primaryTerm : primaryTerm;
-
             var generation = replicaRequest.primaryRefreshResult.generation();
-            assert Engine.RefreshResult.UNKNOWN_GENERATION < generation : generation;
 
             transportService.sendRequest(
                 transportService.getLocalNode(),

server/src/main/java/org/elasticsearch/action/admin/indices/refresh/TransportUnpromotableShardRefreshAction.java

@@ -22,6 +22,7 @@
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.core.TimeValue;
+import org.elasticsearch.index.engine.Engine;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.injection.guice.Inject;
 import org.elasticsearch.node.NodeClosedException;
@@ -154,12 +155,13 @@ protected void unpromotableShardOperation(
             return;
         }
 
+        var primaryTerm = request.getPrimaryTerm();
+        assert Engine.UNKNOWN_PRIMARY_TERM < primaryTerm : primaryTerm;
+        var segmentGeneration = request.getSegmentGeneration();
+        assert Engine.RefreshResult.UNKNOWN_GENERATION < segmentGeneration : segmentGeneration;
+
         ActionListener.run(responseListener, listener -> {
-            shard.waitForPrimaryTermAndGeneration(
-                request.getPrimaryTerm(),
-                request.getSegmentGeneration(),
-                listener.map(l -> ActionResponse.Empty.INSTANCE)
-            );
+            shard.waitForPrimaryTermAndGeneration(primaryTerm, segmentGeneration, listener.map(l -> ActionResponse.Empty.INSTANCE));
         });
     }
 

server/src/main/java/org/elasticsearch/action/admin/indices/refresh/UnpromotableShardRefreshRequest.java

@@ -63,7 +63,9 @@ public UnpromotableShardRefreshRequest(StreamInput in) throws IOException {
     @Override
     public ActionRequestValidationException validate() {
         ActionRequestValidationException validationException = super.validate();
-        if (segmentGeneration == Engine.RefreshResult.UNKNOWN_GENERATION) {
+        if (segmentGeneration == Engine.RefreshResult.UNKNOWN_GENERATION && primaryTerm == Engine.UNKNOWN_PRIMARY_TERM) {
+            // read-only primary shards (like searchable snapshot shard) return Engine.RefreshResult.NO_REFRESH during refresh
+        } else if (segmentGeneration == Engine.RefreshResult.UNKNOWN_GENERATION) {
             validationException = addValidationError("segment generation is unknown", validationException);
         }
         return validationException;

server/src/main/java/org/elasticsearch/index/engine/ReadOnlyEngine.java

@@ -446,7 +446,7 @@ public RefreshResult refresh(String source) {
 
     @Override
     public void maybeRefresh(String source, ActionListener<RefreshResult> listener) throws EngineException {
-        listener.onResponse(RefreshResult.NO_REFRESH);
+        ActionListener.completeWith(listener, () -> refresh(source));
     }
 
     @Override

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/FrozenSearchableSnapshotsIntegTests.java

@@ -67,6 +67,7 @@
 import static org.elasticsearch.search.aggregations.AggregationBuilders.dateHistogram;
 import static org.elasticsearch.snapshots.SearchableSnapshotsSettings.SEARCHABLE_SNAPSHOT_STORE_TYPE;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailures;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailuresAndResponse;
 import static org.elasticsearch.xpack.searchablesnapshots.SearchableSnapshots.SNAPSHOT_RECOVERY_STATE_FACTORY_KEY;
 import static org.hamcrest.Matchers.containsString;
@@ -521,6 +522,34 @@ public void testRequestCacheOnFrozen() throws Exception {
         }
     }
 
+    public void testRefreshPartiallyMountedIndex() throws Exception {
+        final var index = "index";
+        createIndex(index, 1, 0);
+        populateIndex(index, 1_000);
+
+        final var repository = "repository";
+        createRepository(repository, FsRepository.TYPE, Settings.builder().put("location", randomRepoPath()));
+
+        final var snapshot = "repository";
+        createFullSnapshot(repository, snapshot);
+        assertAcked(indicesAdmin().prepareDelete(index));
+
+        final var partialIndex = "partial-" + index;
+        mountSnapshot(
+            repository,
+            snapshot,
+            index,
+            partialIndex,
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, randomInt(1)).build(),
+            MountSearchableSnapshotRequest.Storage.SHARED_CACHE
+        );
+        ensureGreen(partialIndex);
+
+        // before the fix this would have failed
+        var refreshResult = indicesAdmin().prepareRefresh(partialIndex).execute().actionGet();
+        assertNoFailures(refreshResult);
+    }
+
     public void testTierPreferenceCannotBeRemovedForFrozenIndex() throws Exception {
         final String fsRepoName = randomAlphaOfLength(10);
         final String indexName = randomAlphaOfLength(10).toLowerCase(Locale.ROOT);

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsIntegTests.java

@@ -51,6 +51,7 @@
 import org.elasticsearch.index.shard.IndexLongFieldRange;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.repositories.RepositoryData;
+import org.elasticsearch.repositories.fs.FsRepository;
 import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.search.SearchResponseUtils;
 import org.elasticsearch.snapshots.SnapshotId;
@@ -89,6 +90,7 @@
 import static org.elasticsearch.snapshots.SearchableSnapshotsSettings.SEARCHABLE_SNAPSHOT_STORE_TYPE;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailures;
 import static org.elasticsearch.xpack.searchablesnapshots.SearchableSnapshots.SNAPSHOT_RECOVERY_STATE_FACTORY_KEY;
 import static org.hamcrest.Matchers.allOf;
 import static org.hamcrest.Matchers.containsString;
@@ -1280,6 +1282,34 @@ public void onFailure(Exception e) {
         }
     }
 
+    public void testRefreshFullyMountedIndex() throws Exception {
+        final var index = "index";
+        createIndex(index, 1, 0);
+        populateIndex(index, 1_000);
+
+        final var repository = "repository";
+        createRepository(repository, FsRepository.TYPE, Settings.builder().put("location", randomRepoPath()));
+
+        final var snapshot = "repository";
+        createFullSnapshot(repository, snapshot);
+        assertAcked(indicesAdmin().prepareDelete(index));
+
+        final var fullIndex = "full-" + index;
+        mountSnapshot(
+            repository,
+            snapshot,
+            index,
+            fullIndex,
+            Settings.builder().put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, randomInt(1)).build(),
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
+        );
+        ensureGreen(fullIndex);
+
+        // before the fix this would have failed
+        var refreshResult = indicesAdmin().prepareRefresh(fullIndex).execute().actionGet();
+        assertNoFailures(refreshResult);
+    }
+
     private TaskInfo getTaskForActionFromMaster(String action) {
         ListTasksResponse response = client().execute(
             TransportListTasksAction.TYPE,