isSkipUnavailable() returns Optional<T>

Author: pawankartik-elastic

server/src/main/java/org/elasticsearch/action/admin/indices/resolve/TransportResolveClusterAction.java

@@ -174,7 +174,7 @@ protected void doExecuteForked(Task task, ResolveClusterActionRequest request, A
                 resolveClusterTask.ensureNotCancelled();
                 String clusterAlias = remoteIndices.getKey();
                 OriginalIndices originalIndices = remoteIndices.getValue();
-                boolean skipUnavailable = remoteClusterService.isSkipUnavailable(clusterAlias);
+                boolean skipUnavailable = remoteClusterService.isSkipUnavailable(clusterAlias).orElse(true) == false;
                 RemoteClusterClient remoteClusterClient = remoteClusterService.getRemoteClusterClient(
                     clusterAlias,
                     searchCoordinationExecutor,

server/src/main/java/org/elasticsearch/action/fieldcaps/TransportFieldCapabilitiesAction.java

@@ -332,7 +332,7 @@ private void doExecuteForked(
                 );
 
                 boolean ensureConnected = forceConnectTimeoutSecs != null
-                    || transportService.getRemoteClusterService().isSkipUnavailable(clusterAlias) == false;
+                    || transportService.getRemoteClusterService().isSkipUnavailable(clusterAlias).orElse(true) == false;
                 transportService.getRemoteClusterService()
                     .maybeEnsureConnectedAndGetConnection(clusterAlias, ensureConnected, connectionListener);
             }

server/src/main/java/org/elasticsearch/transport/RemoteClusterService.java

@@ -48,6 +48,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
@@ -160,7 +161,7 @@ public boolean isRemoteClusterServerEnabled() {
     private final Map<ProjectId, Map<String, RemoteClusterConnection>> remoteClusters;
     private final RemoteClusterCredentialsManager remoteClusterCredentialsManager;
     private final ProjectResolver projectResolver;
-    private final boolean inSkippableContext;
+    private final boolean isCpsEnabled;
 
     @FixForMultiProject(description = "Inject the ProjectResolver instance.")
     RemoteClusterService(Settings settings, TransportService transportService) {
@@ -182,7 +183,7 @@ public boolean isRemoteClusterServerEnabled() {
          * TODO: This is not the right way to check if we're in CPS context and is more of a temporary measure since
          *  the functionality to do it the right way is not yet ready -- replace this code when it's ready.
          */
-        this.inSkippableContext = settings.getAsBoolean("serverless.cross_project.enabled", false);
+        this.isCpsEnabled = settings.getAsBoolean("serverless.cross_project.enabled", false);
     }
 
     /**
@@ -293,22 +294,28 @@ void ensureConnected(String clusterAlias, ActionListener<Void> listener) {
     }
 
     /**
-     * Returns whether the cluster identified by the provided alias is configured to be skipped when unavailable
+     * Returns whether the cluster identified by the provided alias is configured to be skipped when unavailable.
+     * @param clusterAlias Name of the cluster
+     * @return A boolean optional that denotes if the cluster is configured to be skipped. In CPS-like environment,
+     * it returns an empty value where we default/fall back to true.
      */
-    public boolean isSkipUnavailable(String clusterAlias) {
-        return getRemoteClusterConnection(clusterAlias).isSkipUnavailable();
+    public Optional<Boolean> isSkipUnavailable(String clusterAlias) {
+        if (isCpsEnabled) {
+            return Optional.empty();
+        } else {
+            return Optional.of(getRemoteClusterConnection(clusterAlias).isSkipUnavailable());
+        }
     }
 
     /**
-     * Returns whether we're in a skippable context. Skippable context is true when either in CPS environment
-     * or skip_unavailable is set to true for the specified cluster.
+     * Signifies if an error can be skipped for the specified cluster based on skip_unavailable, or,
+     * allow_partial_search_results if in CPS-like environment.
      * @param clusterAlias Name of the cluster
      * @param allowPartialSearchResults If partial results can be served for the search request.
      * @return boolean
      */
     public boolean shouldSkipOnFailure(String clusterAlias, Boolean allowPartialSearchResults) {
-        return (inSkippableContext && (allowPartialSearchResults != null && allowPartialSearchResults))
-            || getRemoteClusterConnection(clusterAlias).isSkipUnavailable();
+        return isSkipUnavailable(clusterAlias).orElseGet(() -> allowPartialSearchResults != null && allowPartialSearchResults);
     }
 
     public Transport.Connection getConnection(String cluster) {
@@ -675,7 +682,9 @@ public RemoteClusterClient getRemoteClusterClient(
         return new RemoteClusterAwareClient(transportService, clusterAlias, responseExecutor, switch (disconnectedStrategy) {
             case RECONNECT_IF_DISCONNECTED -> true;
             case FAIL_IF_DISCONNECTED -> false;
-            case RECONNECT_UNLESS_SKIP_UNAVAILABLE -> transportService.getRemoteClusterService().isSkipUnavailable(clusterAlias) == false;
+            case RECONNECT_UNLESS_SKIP_UNAVAILABLE -> transportService.getRemoteClusterService()
+                .isSkipUnavailable(clusterAlias)
+                .orElse(true) == false;
         });
     }
 

server/src/test/java/org/elasticsearch/transport/RemoteClusterServiceTests.java

@@ -1370,15 +1370,15 @@ public void testSkipUnavailable() {
                 service.start();
                 service.acceptIncomingRequests();
 
-                assertTrue(service.getRemoteClusterService().isSkipUnavailable("cluster1"));
+                assertTrue(service.getRemoteClusterService().isSkipUnavailable("cluster1").orElse(true));
 
                 if (randomBoolean()) {
                     updateSkipUnavailable(service.getRemoteClusterService(), "cluster1", false);
-                    assertFalse(service.getRemoteClusterService().isSkipUnavailable("cluster1"));
+                    assertFalse(service.getRemoteClusterService().isSkipUnavailable("cluster1").orElse(true));
                 }
 
                 updateSkipUnavailable(service.getRemoteClusterService(), "cluster1", true);
-                assertTrue(service.getRemoteClusterService().isSkipUnavailable("cluster1"));
+                assertTrue(service.getRemoteClusterService().isSkipUnavailable("cluster1").orElse(true));
             }
         }
     }