`getRemoteClusterClient` does not need a `ThreadPool` (#104557)

Following #104536 this argument is now unused.

modules/lang-painless/src/main/java/org/elasticsearch/painless/action/PainlessExecuteAction.java

@@ -528,7 +528,7 @@ public class PainlessExecuteAction {
                 // forward to remote cluster
                 String clusterAlias = request.getContextSetup().getClusterAlias();
                 transportService.getRemoteClusterService()
-                    .getRemoteClusterClient(threadPool, clusterAlias, EsExecutors.DIRECT_EXECUTOR_SERVICE)
+                    .getRemoteClusterClient(clusterAlias, EsExecutors.DIRECT_EXECUTOR_SERVICE)
                     .execute(PainlessExecuteAction.INSTANCE, request, listener);
             }
         }

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

@@ -493,7 +493,6 @@ public class ResolveIndexAction extends ActionType<ResolveIndexAction.Response>
                     String clusterAlias = remoteIndices.getKey();
                     OriginalIndices originalIndices = remoteIndices.getValue();
                     var remoteClusterClient = remoteClusterService.getRemoteClusterClient(
-                        threadPool,
                         clusterAlias,
                         EsExecutors.DIRECT_EXECUTOR_SERVICE
                     );

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

@@ -213,7 +213,7 @@ public class TransportFieldCapabilitiesAction extends HandledTransportAction<Fie
                 String clusterAlias = remoteIndices.getKey();
                 OriginalIndices originalIndices = remoteIndices.getValue();
                 var remoteClusterClient = transportService.getRemoteClusterService()
-                    .getRemoteClusterClient(threadPool, clusterAlias, searchCoordinationExecutor);
+                    .getRemoteClusterClient(clusterAlias, searchCoordinationExecutor);
                 FieldCapabilitiesRequest remoteRequest = prepareRemoteRequest(request, originalIndices, nowInMillis);
                 ActionListener<FieldCapabilitiesResponse> remoteListener = ActionListener.wrap(response -> {
                     for (FieldCapabilitiesIndexResponse resp : response.getIndexResponses()) {

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

@@ -525,7 +525,7 @@ public class TransportSearchAction extends HandledTransportAction<SearchRequest,
                 timeProvider.absoluteStartMillis(),
                 true
             );
-            var remoteClusterClient = remoteClusterService.getRemoteClusterClient(threadPool, clusterAlias, remoteClientResponseExecutor);
+            var remoteClusterClient = remoteClusterService.getRemoteClusterClient(clusterAlias, remoteClientResponseExecutor);
             remoteClusterClient.execute(TransportSearchAction.TYPE, ccsSearchRequest, new ActionListener<>() {
                 @Override
                 public void onResponse(SearchResponse searchResponse) {
@@ -604,11 +604,7 @@ public class TransportSearchAction extends HandledTransportAction<SearchRequest,
                     task.getProgressListener(),
                     listener
                 );
-                final var remoteClusterClient = remoteClusterService.getRemoteClusterClient(
-                    threadPool,
-                    clusterAlias,
-                    remoteClientResponseExecutor
-                );
+                final var remoteClusterClient = remoteClusterService.getRemoteClusterClient(clusterAlias, remoteClientResponseExecutor);
                 remoteClusterClient.execute(TransportSearchAction.TYPE, ccsSearchRequest, ccsListener);
             }
             if (localIndices != null) {

server/src/main/java/org/elasticsearch/client/internal/node/NodeClient.java

@@ -138,6 +138,6 @@ public class NodeClient extends AbstractClient {
 
     @Override
     public RemoteClusterClient getRemoteClusterClient(String clusterAlias, Executor responseExecutor) {
-        return remoteClusterService.getRemoteClusterClient(threadPool(), clusterAlias, responseExecutor, true);
+        return remoteClusterService.getRemoteClusterClient(clusterAlias, responseExecutor, true);
     }
 }

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

@@ -32,7 +32,6 @@ import org.elasticsearch.common.util.concurrent.EsExecutors;
 import org.elasticsearch.core.IOUtils;
 import org.elasticsearch.core.TimeValue;
 import org.elasticsearch.node.ReportingService;
-import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.RemoteClusterCredentialsManager.UpdateRemoteClusterCredentialsResult;
 
 import java.io.Closeable;
@@ -544,18 +543,12 @@ public final class RemoteClusterService extends RemoteClusterAware implements Cl
     /**
      * Returns a client to the remote cluster if the given cluster alias exists.
      *
-     * @param threadPool       the {@link ThreadPool} for the client
      * @param clusterAlias     the cluster alias the remote cluster is registered under
      * @param responseExecutor the executor to use to process the response
      * @param ensureConnected  whether requests should wait for a connection attempt when there isn't a connection available
      * @throws IllegalArgumentException if the given clusterAlias doesn't exist
      */
-    public RemoteClusterClient getRemoteClusterClient(
-        ThreadPool threadPool,
-        String clusterAlias,
-        Executor responseExecutor,
-        boolean ensureConnected
-    ) {
+    public RemoteClusterClient getRemoteClusterClient(String clusterAlias, Executor responseExecutor, boolean ensureConnected) {
         if (transportService.getRemoteClusterService().isEnabled() == false) {
             throw new IllegalArgumentException(
                 "this node does not have the " + DiscoveryNodeRole.REMOTE_CLUSTER_CLIENT_ROLE.roleName() + " role"
@@ -570,14 +563,12 @@ public final class RemoteClusterService extends RemoteClusterAware implements Cl
     /**
      * Returns a client to the remote cluster if the given cluster alias exists.
      *
-     * @param threadPool       the {@link ThreadPool} for the client
      * @param clusterAlias     the cluster alias the remote cluster is registered under
      * @param responseExecutor the executor to use to process the response
      * @throws IllegalArgumentException if the given clusterAlias doesn't exist
      */
-    public RemoteClusterClient getRemoteClusterClient(ThreadPool threadPool, String clusterAlias, Executor responseExecutor) {
+    public RemoteClusterClient getRemoteClusterClient(String clusterAlias, Executor responseExecutor) {
         return getRemoteClusterClient(
-            threadPool,
             clusterAlias,
             responseExecutor,
             transportService.getRemoteClusterService().isSkipUnavailable(clusterAlias) == false

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

@@ -95,7 +95,6 @@ public class RemoteClusterClientTests extends ESTestCase {
                 RemoteClusterService remoteClusterService = service.getRemoteClusterService();
                 assertTrue(remoteClusterService.isRemoteNodeConnected("test", remoteNode));
                 var client = remoteClusterService.getRemoteClusterClient(
-                    threadPool,
                     "test",
                     threadPool.executor(TEST_THREAD_POOL_NAME),
                     randomBoolean()
@@ -172,7 +171,7 @@ public class RemoteClusterClientTests extends ESTestCase {
                     connectionManager.disconnectFromNode(remoteNode);
                     closeFuture.get();
 
-                    var client = remoteClusterService.getRemoteClusterClient(threadPool, "test", EsExecutors.DIRECT_EXECUTOR_SERVICE, true);
+                    var client = remoteClusterService.getRemoteClusterClient("test", EsExecutors.DIRECT_EXECUTOR_SERVICE, true);
                     ClusterStateResponse clusterStateResponse = PlainActionFuture.get(
                         f -> client.execute(ClusterStateAction.INSTANCE, new ClusterStateRequest(), f)
                     );
@@ -200,7 +199,7 @@ public class RemoteClusterClientTests extends ESTestCase {
             final RemoteClusterService remoteClusterService = service.getRemoteClusterService();
             final IllegalArgumentException e = expectThrows(
                 IllegalArgumentException.class,
-                () -> remoteClusterService.getRemoteClusterClient(threadPool, "test", EsExecutors.DIRECT_EXECUTOR_SERVICE, randomBoolean())
+                () -> remoteClusterService.getRemoteClusterClient("test", EsExecutors.DIRECT_EXECUTOR_SERVICE, randomBoolean())
             );
             assertThat(e.getMessage(), equalTo("this node does not have the remote_cluster_client role"));
         }
@@ -243,7 +242,7 @@ public class RemoteClusterClientTests extends ESTestCase {
                 service.start();
                 service.acceptIncomingRequests();
                 RemoteClusterService remoteClusterService = service.getRemoteClusterService();
-                var client = remoteClusterService.getRemoteClusterClient(threadPool, "test", EsExecutors.DIRECT_EXECUTOR_SERVICE);
+                var client = remoteClusterService.getRemoteClusterClient("test", EsExecutors.DIRECT_EXECUTOR_SERVICE);
 
                 try {
                     assertFalse(remoteClusterService.isRemoteNodeConnected("test", remoteNode));

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/termsenum/action/TransportTermsEnumAction.java

@@ -624,11 +624,7 @@ public class TransportTermsEnumAction extends HandledTransportAction<TermsEnumRe
             try {
                 TermsEnumRequest req = new TermsEnumRequest(request).indices(remoteIndices.indices());
 
-                var remoteClient = remoteClusterService.getRemoteClusterClient(
-                    transportService.getThreadPool(),
-                    clusterAlias,
-                    EsExecutors.DIRECT_EXECUTOR_SERVICE
-                );
+                var remoteClient = remoteClusterService.getRemoteClusterClient(clusterAlias, EsExecutors.DIRECT_EXECUTOR_SERVICE);
                 remoteClient.execute(TermsEnumAction.INSTANCE, req, new ActionListener<>() {
                     @Override
                     public void onResponse(TermsEnumResponse termsEnumResponse) {

x-pack/plugin/security/qa/multi-cluster/src/javaRestTest/java/org/elasticsearch/xpack/remotecluster/RemoteClusterSecurityFcActionAuthorizationIT.java

@@ -167,11 +167,7 @@ public class RemoteClusterSecurityFcActionAuthorizationIT extends ESRestTestCase
             assertThat(remoteConnectionInfos, hasSize(1));
             assertThat(remoteConnectionInfos.get(0).isConnected(), is(true));
 
-            final var remoteClusterClient = remoteClusterService.getRemoteClusterClient(
-                threadPool,
-                "my_remote_cluster",
-                threadPool.generic()
-            );
+            final var remoteClusterClient = remoteClusterService.getRemoteClusterClient("my_remote_cluster", threadPool.generic());
 
             // Creating a restore session fails if index is not accessible
             final ShardId privateShardId = new ShardId("private-index", privateIndexUUID, 0);
@@ -315,7 +311,6 @@ public class RemoteClusterSecurityFcActionAuthorizationIT extends ESRestTestCase
         try (MockTransportService service = startTransport("node", threadPool, (String) apiKeyMap.get("encoded"))) {
             final RemoteClusterService remoteClusterService = service.getRemoteClusterService();
             final var remoteClusterClient = remoteClusterService.getRemoteClusterClient(
-                threadPool,
                 "my_remote_cluster",
                 EsExecutors.DIRECT_EXECUTOR_SERVICE
             );
@@ -389,7 +384,6 @@ public class RemoteClusterSecurityFcActionAuthorizationIT extends ESRestTestCase
             assertThat(remoteConnectionInfos, hasSize(1));
             assertThat(remoteConnectionInfos.get(0).isConnected(), is(true));
             final var remoteClusterClient = remoteClusterService.getRemoteClusterClient(
-                threadPool,
                 "my_remote_cluster",
                 EsExecutors.DIRECT_EXECUTOR_SERVICE
             );