Introduce a dedicated ProjectClient interface

modules/ingest-geoip/src/main/java/org/elasticsearch/ingest/geoip/GeoIpDownloader.java

@@ -16,7 +16,7 @@
 import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
 import org.elasticsearch.action.index.IndexRequest;
 import org.elasticsearch.action.support.PlainActionFuture;
-import org.elasticsearch.client.internal.Client;
+import org.elasticsearch.client.internal.ProjectClient;
 import org.elasticsearch.cluster.block.ClusterBlockLevel;
 import org.elasticsearch.cluster.metadata.ProjectId;
 import org.elasticsearch.cluster.service.ClusterService;
@@ -77,7 +77,7 @@ public class GeoIpDownloader extends AllocatedPersistentTask {
     static final String DATABASES_INDEX_PATTERN = DATABASES_INDEX + "*";
     static final int MAX_CHUNK_SIZE = 1024 * 1024;
 
-    private final Client client;
+    private final ProjectClient client;
     private final HttpClient httpClient;
     private final ClusterService clusterService;
     private final ThreadPool threadPool;
@@ -99,7 +99,7 @@ public class GeoIpDownloader extends AllocatedPersistentTask {
     private final ProjectId projectId;
 
     GeoIpDownloader(
-        Client client,
+        ProjectClient client,
         HttpClient httpClient,
         ClusterService clusterService,
         ThreadPool threadPool,
@@ -116,7 +116,7 @@ public class GeoIpDownloader extends AllocatedPersistentTask {
         ProjectId projectId
     ) {
         super(id, type, action, description, parentTask, headers);
-        this.client = client.projectClient(projectId);
+        this.client = client;
         this.httpClient = httpClient;
         this.clusterService = clusterService;
         this.threadPool = threadPool;

modules/ingest-geoip/src/main/java/org/elasticsearch/ingest/geoip/GeoIpDownloaderTaskExecutor.java

@@ -191,7 +191,7 @@ protected GeoIpDownloader createTask(
     ) {
         ProjectId projectId = projectResolver.getProjectId();
         return new GeoIpDownloader(
-            client,
+            client.projectClient(projectId),
             httpClient,
             clusterService,
             threadPool,

modules/ingest-geoip/src/test/java/org/elasticsearch/ingest/geoip/DatabaseNodeServiceTests.java

@@ -17,6 +17,7 @@
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.client.internal.Client;
+import org.elasticsearch.client.internal.ProjectClient;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.metadata.AliasMetadata;
@@ -63,6 +64,7 @@
 import org.junit.After;
 import org.junit.Before;
 import org.mockito.ArgumentCaptor;
+import org.mockito.Mockito;
 import org.mockito.stubbing.Answer;
 
 import java.io.ByteArrayInputStream;
@@ -112,6 +114,7 @@
 public class DatabaseNodeServiceTests extends ESTestCase {
 
     private Client client;
+    private ProjectClient projectClient;
     private Path geoIpTmpDir;
     private ThreadPool threadPool;
     private DatabaseNodeService databaseNodeService;
@@ -138,7 +141,9 @@ public void setup() throws IOException {
         Settings settings = Settings.builder().put("resource.reload.interval.high", TimeValue.timeValueMillis(100)).build();
         resourceWatcherService = new ResourceWatcherService(settings, threadPool);
 
+        projectClient = mock(ProjectClient.class);
         client = mock(Client.class);
+        when(client.projectClient(any())).thenReturn(projectClient);
         ingestService = mock(IngestService.class);
         clusterService = mock(ClusterService.class);
         geoIpTmpDir = createTempDir();
@@ -161,6 +166,8 @@ public void cleanup() {
         threadPool.shutdownNow();
         Releasables.close(toRelease);
         toRelease.clear();
+        verify(client, Mockito.atLeast(0)).projectClient(any());
+        verifyNoMoreInteractions(client);
     }
 
     public void testCheckDatabases() throws Exception {
@@ -181,7 +188,7 @@ public void testCheckDatabases() throws Exception {
         databaseNodeService.checkDatabases(state);
         DatabaseReaderLazyLoader database = databaseNodeService.getDatabaseReaderLazyLoader(projectId, "GeoIP2-City.mmdb");
         assertThat(database, nullValue());
-        verify(client, times(0)).search(any());
+        verify(projectClient, times(0)).search(any());
         verify(ingestService, times(0)).reloadPipeline(any(), anyString());
         try (Stream<Path> files = Files.list(geoIpTmpDir.resolve("geoip-databases").resolve("nodeId"))) {
             assertEquals(0, files.count());
@@ -199,7 +206,7 @@ public void testCheckDatabases() throws Exception {
         databaseNodeService.checkDatabases(state);
         database = databaseNodeService.getDatabaseReaderLazyLoader(projectId, "GeoIP2-City.mmdb");
         assertThat(database, notNullValue());
-        verify(client, times(10)).search(any());
+        verify(projectClient, times(10)).search(any());
         try (Stream<Path> files = Files.list(geoIpTmpDir.resolve("geoip-databases").resolve("nodeId"))) {
             assertThat(files.count(), greaterThanOrEqualTo(1L));
         }
@@ -226,7 +233,7 @@ public void testCheckDatabases_dontCheckDatabaseOnNonIngestNode() throws Excepti
 
         databaseNodeService.checkDatabases(state);
         assertThat(databaseNodeService.getDatabase(projectId, "GeoIP2-City.mmdb"), nullValue());
-        verify(client, never()).search(any());
+        verify(projectClient, never()).search(any());
         try (Stream<Path> files = Files.list(geoIpTmpDir.resolve("geoip-databases").resolve("nodeId"))) {
             assertThat(files.toList(), empty());
         }
@@ -246,7 +253,7 @@ public void testCheckDatabases_dontCheckDatabaseWhenNoDatabasesIndex() throws Ex
 
         databaseNodeService.checkDatabases(state);
         assertThat(databaseNodeService.getDatabase(projectId, "GeoIP2-City.mmdb"), nullValue());
-        verify(client, never()).search(any());
+        verify(projectClient, never()).search(any());
         try (Stream<Path> files = Files.list(geoIpTmpDir.resolve("geoip-databases").resolve("nodeId"))) {
             assertThat(files.toList(), empty());
         }
@@ -261,7 +268,7 @@ public void testCheckDatabases_dontCheckDatabaseWhenGeoIpDownloadTask() throws E
 
         databaseNodeService.checkDatabases(state);
         assertThat(databaseNodeService.getDatabase(projectId, "GeoIP2-City.mmdb"), nullValue());
-        verify(client, never()).search(any());
+        verify(projectClient, never()).search(any());
         try (Stream<Path> files = Files.list(geoIpTmpDir.resolve("geoip-databases").resolve("nodeId"))) {
             assertThat(files.toList(), empty());
         }
@@ -281,7 +288,7 @@ public void testRetrieveDatabase() throws Exception {
         verify(failureHandler, never()).accept(any());
         verify(chunkConsumer, times(30)).accept(any());
         verify(completedHandler, times(1)).run();
-        verify(client, times(30)).search(any());
+        verify(projectClient, times(30)).search(any());
     }
 
     public void testRetrieveDatabaseCorruption() throws Exception {
@@ -305,7 +312,7 @@ public void testRetrieveDatabaseCorruption() throws Exception {
         );
         verify(chunkConsumer, times(10)).accept(any());
         verify(completedHandler, times(0)).run();
-        verify(client, times(10)).search(any());
+        verify(projectClient, times(10)).search(any());
     }
 
     public void testUpdateDatabase() throws Exception {
@@ -371,8 +378,7 @@ private String mockSearches(String databaseName, int firstChunk, int lastChunk)
             });
             requestMap.put(databaseName + "_" + i, actionFuture);
         }
-        when(client.projectClient(any())).thenReturn(client);
-        when(client.search(any())).thenAnswer(invocationOnMock -> {
+        when(projectClient.search(any())).thenAnswer(invocationOnMock -> {
             SearchRequest req = (SearchRequest) invocationOnMock.getArguments()[0];
             TermQueryBuilder term = (TermQueryBuilder) req.source().query();
             String id = (String) term.value();

modules/ingest-geoip/src/test/java/org/elasticsearch/ingest/geoip/GeoIpDownloaderTests.java

@@ -23,6 +23,7 @@
 import org.elasticsearch.action.index.IndexResponse;
 import org.elasticsearch.action.index.TransportIndexAction;
 import org.elasticsearch.action.support.broadcast.BroadcastResponse;
+import org.elasticsearch.client.internal.ProjectClient;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.block.ClusterBlocks;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
@@ -702,12 +703,14 @@ private GeoIpTaskState.Metadata newGeoIpTaskStateMetadata(boolean expired) {
         return new GeoIpTaskState.Metadata(0, 0, 0, randomAlphaOfLength(20), lastChecked.toEpochMilli());
     }
 
-    private static class MockClient extends NoOpClient {
+    private static class MockClient extends NoOpClient implements ProjectClient {
 
         private final Map<ActionType<?>, BiConsumer<? extends ActionRequest, ? extends ActionListener<?>>> handlers = new HashMap<>();
+        private final ProjectId projectId;
 
         private MockClient(ThreadPool threadPool, ProjectId projectId) {
             super(threadPool, TestProjectResolvers.singleProject(projectId));
+            this.projectId = projectId;
         }
 
         public <Response extends ActionResponse, Request extends ActionRequest> void addHandler(
@@ -717,6 +720,11 @@ public <Response extends ActionResponse, Request extends ActionRequest> void add
             handlers.put(action, listener);
         }
 
+        @Override
+        public ProjectId projectId() {
+            return projectId;
+        }
+
         @SuppressWarnings("unchecked")
         @Override
         protected <Request extends ActionRequest, Response extends ActionResponse> void doExecute(

server/src/main/java/org/elasticsearch/client/internal/Client.java

@@ -404,7 +404,7 @@ public interface Client extends ElasticsearchClient {
     /**
      * Returns a client that executes every request in the context of the given project.
      */
-    Client projectClient(ProjectId projectId);
+    ProjectClient projectClient(ProjectId projectId);
 
     /**
      * Returns this client's project resolver.

server/src/main/java/org/elasticsearch/client/internal/ProjectClient.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.client.internal;
+
+import org.elasticsearch.cluster.metadata.ProjectId;
+
+/**
+ * A {@link Client} that is scoped to a specific project. It should execute any request in the scope of that project. This scope is usually
+ * defined by the thread context.
+ */
+public interface ProjectClient extends Client {
+
+    ProjectId projectId();
+}

server/src/main/java/org/elasticsearch/client/internal/support/AbstractClient.java

@@ -76,8 +76,10 @@
 import org.elasticsearch.client.internal.AdminClient;
 import org.elasticsearch.client.internal.Client;
 import org.elasticsearch.client.internal.FilterClient;
+import org.elasticsearch.client.internal.ProjectClient;
 import org.elasticsearch.cluster.metadata.ProjectId;
 import org.elasticsearch.cluster.project.ProjectResolver;
+import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.core.Nullable;
@@ -96,6 +98,7 @@ public abstract class AbstractClient implements Client {
     private final ThreadPool threadPool;
     private final ProjectResolver projectResolver;
     private final AdminClient admin;
+    private final ProjectClient defaultProjectClient;
 
     @SuppressWarnings("this-escape")
     public AbstractClient(Settings settings, ThreadPool threadPool, ProjectResolver projectResolver) {
@@ -104,6 +107,14 @@ public AbstractClient(Settings settings, ThreadPool threadPool, ProjectResolver
         this.projectResolver = projectResolver;
         this.admin = new AdminClient(this);
         this.logger = LogManager.getLogger(this.getClass());
+        // We create a dedicated project client for the default project to avoid having to reconstruct it on every invocation.
+        // This aims to reduce the overhead of creating a project client when the client is used in a single-project context.
+        // TODO: only create the default project client if the project resolver does not support multiple projects.
+        if (this instanceof ProjectClient == false) {
+            this.defaultProjectClient = new ProjectClientImpl(this, ProjectId.DEFAULT);
+        } else {
+            this.defaultProjectClient = null;
+        }
     }
 
     @Override
@@ -417,29 +428,13 @@ protected <Request extends ActionRequest, Response extends ActionResponse> void
     }
 
     @Override
-    public Client projectClient(ProjectId projectId) {
+    public ProjectClient projectClient(ProjectId projectId) {
         // We only take the shortcut when the given project ID matches the "current" project ID. If it doesn't, we'll let #executeOnProject
         // take care of error handling.
         if (projectResolver.supportsMultipleProjects() == false && projectId.equals(projectResolver.getProjectId())) {
-            return this;
+            return defaultProjectClient;
         }
-        return new FilterClient(this) {
-            @Override
-            protected <Request extends ActionRequest, Response extends ActionResponse> void doExecute(
-                ActionType<Response> action,
-                Request request,
-                ActionListener<Response> listener
-            ) {
-                projectResolver.executeOnProject(projectId, () -> super.doExecute(action, request, listener));
-            }
-
-            @Override
-            public Client projectClient(ProjectId projectId) {
-                throw new IllegalStateException(
-                    "Unable to create a project client for project [" + projectId + "], nested project client creation is not supported"
-                );
-            }
-        };
+        return new ProjectClientImpl(this, projectId);
     }
 
     /**
@@ -477,4 +472,35 @@ public R get() throws InterruptedException, ExecutionException {
             return super.get();
         }
     }
+
+    private static class ProjectClientImpl extends FilterClient implements ProjectClient {
+
+        private final ProjectId projectId;
+
+        ProjectClientImpl(Client in, ProjectId projectId) {
+            super(in);
+            this.projectId = projectId;
+        }
+
+        @Override
+        public ProjectId projectId() {
+            return projectId;
+        }
+
+        @Override
+        protected <Request extends ActionRequest, Response extends ActionResponse> void doExecute(
+            ActionType<Response> action,
+            Request request,
+            ActionListener<Response> listener
+        ) {
+            projectResolver().executeOnProject(projectId, () -> super.doExecute(action, request, listener));
+        }
+
+        @Override
+        public ProjectClient projectClient(ProjectId projectId) {
+            throw new IllegalStateException(Strings.format("""
+                Unable to create a project client for project [%s] from project client with project ID [%s],\
+                 nested project client creation is not supported""", projectId, this.projectId));
+        }
+    }
 }

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/AbstractStepTestCase.java

@@ -10,6 +10,7 @@
 import org.elasticsearch.client.internal.AdminClient;
 import org.elasticsearch.client.internal.Client;
 import org.elasticsearch.client.internal.IndicesAdminClient;
+import org.elasticsearch.client.internal.ProjectClient;
 import org.elasticsearch.cluster.ClusterStateObserver;
 import org.elasticsearch.cluster.ProjectState;
 import org.elasticsearch.cluster.metadata.IndexMetadata;
@@ -26,6 +27,7 @@
 public abstract class AbstractStepTestCase<T extends Step> extends ESTestCase {
 
     protected Client client;
+    protected ProjectClient projectClient;
     protected AdminClient adminClient;
     protected IndicesAdminClient indicesClient;
 
@@ -34,9 +36,10 @@ public void setupClient() {
         client = Mockito.mock(Client.class);
         adminClient = Mockito.mock(AdminClient.class);
         indicesClient = Mockito.mock(IndicesAdminClient.class);
+        projectClient = Mockito.mock(ProjectClient.class);
 
-        Mockito.when(client.projectClient(Mockito.any())).thenReturn(client);
-        Mockito.when(client.admin()).thenReturn(adminClient);
+        Mockito.when(client.projectClient(Mockito.any())).thenReturn(projectClient);
+        Mockito.when(projectClient.admin()).thenReturn(adminClient);
         Mockito.when(adminClient.indices()).thenReturn(indicesClient);
     }
 

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/CleanupSnapshotStepTests.java

@@ -16,6 +16,7 @@
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.cluster.metadata.LifecycleExecutionState;
 import org.elasticsearch.cluster.metadata.ProjectMetadata;
+import org.elasticsearch.cluster.project.TestProjectResolvers;
 import org.elasticsearch.index.IndexVersion;
 import org.elasticsearch.test.client.NoOpClient;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -105,7 +106,7 @@ public void testPerformAction() {
     }
 
     private NoOpClient getDeleteSnapshotRequestAssertingClient(ThreadPool threadPool, String expectedSnapshotName) {
-        return new NoOpClient(threadPool) {
+        return new NoOpClient(threadPool, TestProjectResolvers.usingRequestHeader(threadPool.getThreadContext())) {
             @Override
             protected <Request extends ActionRequest, Response extends ActionResponse> void doExecute(
                 ActionType<Response> action,

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/CloseIndexStepTests.java

@@ -82,7 +82,7 @@ public void onFailure(Exception e) {
 
         assertEquals(true, actionCompleted.get());
         Mockito.verify(client).projectClient(state.projectId());
-        Mockito.verify(client).admin();
+        Mockito.verify(projectClient).admin();
         Mockito.verifyNoMoreInteractions(client);
         Mockito.verify(adminClient, Mockito.only()).indices();
         Mockito.verify(indicesClient, Mockito.only()).close(Mockito.any(), Mockito.any());
@@ -110,7 +110,7 @@ public void testPerformActionFailure() {
 
         assertSame(exception, expectThrows(Exception.class, () -> performActionAndWait(step, indexMetadata, state, null)));
         Mockito.verify(client).projectClient(state.projectId());
-        Mockito.verify(client).admin();
+        Mockito.verify(projectClient).admin();
         Mockito.verifyNoMoreInteractions(client);
         Mockito.verify(adminClient, Mockito.only()).indices();
         Mockito.verify(indicesClient, Mockito.only()).close(Mockito.any(), Mockito.any());