Address review comments

Author: alexey-ivanov-es

server/src/main/java/org/elasticsearch/cluster/ClusterModule.java

@@ -28,7 +28,7 @@
 import org.elasticsearch.cluster.metadata.RepositoriesMetadata;
 import org.elasticsearch.cluster.metadata.StreamsMetadata;
 import org.elasticsearch.cluster.project.ProjectResolver;
-import org.elasticsearch.cluster.project.ProjectsStateRegistry;
+import org.elasticsearch.cluster.project.ProjectStateRegistry;
 import org.elasticsearch.cluster.routing.DelayedAllocationService;
 import org.elasticsearch.cluster.routing.ShardRouting;
 import org.elasticsearch.cluster.routing.ShardRoutingRoleStrategy;
@@ -293,7 +293,7 @@ public static List<Entry> getNamedWriteables() {
             RegisteredPolicySnapshots::new,
             RegisteredPolicySnapshots.RegisteredSnapshotsDiff::new
         );
-        registerClusterCustom(entries, ProjectsStateRegistry.TYPE, ProjectsStateRegistry::new, ProjectsStateRegistry::readDiffFrom);
+        registerClusterCustom(entries, ProjectStateRegistry.TYPE, ProjectStateRegistry::new, ProjectStateRegistry::readDiffFrom);
         // Secrets
         registerClusterCustom(entries, ClusterSecrets.TYPE, ClusterSecrets::new, ClusterSecrets::readDiffFrom);
         registerProjectCustom(entries, ProjectSecrets.TYPE, ProjectSecrets::new, ProjectSecrets::readDiffFrom);

server/src/main/java/org/elasticsearch/cluster/ProjectState.java

@@ -12,7 +12,7 @@
 import org.elasticsearch.cluster.block.ClusterBlocks;
 import org.elasticsearch.cluster.metadata.ProjectId;
 import org.elasticsearch.cluster.metadata.ProjectMetadata;
-import org.elasticsearch.cluster.project.ProjectsStateRegistry;
+import org.elasticsearch.cluster.project.ProjectStateRegistry;
 import org.elasticsearch.cluster.routing.RoutingTable;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
@@ -37,7 +37,7 @@ public final class ProjectState {
         this.cluster = clusterState;
         this.project = projectId;
         this.projectMetadata = clusterState.metadata().getProject(projectId);
-        this.projectSettings = ProjectsStateRegistry.getProjectSettings(projectId, clusterState);
+        this.projectSettings = ProjectStateRegistry.getProjectSettings(projectId, clusterState);
         this.routingTable = clusterState.routingTable(projectId);
     }
 

server/src/main/java/org/elasticsearch/cluster/project/ProjectsStateRegistry.java renamed to server/src/main/java/org/elasticsearch/cluster/project/ProjectStateRegistry.java

@@ -27,22 +27,33 @@
 import java.util.Iterator;
 import java.util.Map;
 
-public class ProjectsStateRegistry extends AbstractNamedDiffable<ClusterState.Custom> implements ClusterState.Custom {
+/**
+ * Represents a registry for managing and retrieving project-specific state in the cluster state.
+ */
+public class ProjectStateRegistry extends AbstractNamedDiffable<ClusterState.Custom> implements ClusterState.Custom {
     public static final String TYPE = "projects_registry";
-    public static final ProjectsStateRegistry EMPTY = new ProjectsStateRegistry(Collections.emptyMap());
+    public static final ProjectStateRegistry EMPTY = new ProjectStateRegistry(Collections.emptyMap());
 
     private final Map<ProjectId, Settings> projectsSettings;
 
-    public ProjectsStateRegistry(StreamInput in) throws IOException {
+    public ProjectStateRegistry(StreamInput in) throws IOException {
         projectsSettings = in.readMap(ProjectId::readFrom, Settings::readSettingsFromStream);
     }
 
-    public ProjectsStateRegistry(Map<ProjectId, Settings> projectsSettings) {
+    private ProjectStateRegistry(Map<ProjectId, Settings> projectsSettings) {
         this.projectsSettings = projectsSettings;
     }
 
+    /**
+     * Retrieves the settings for a specific project based on its project ID from the specified cluster state without creating a new object.
+     * If you need a full state of the project rather than just its setting, please use {@link ClusterState#projectState(ProjectId)}
+     *
+     * @param projectId id of the project
+     * @param clusterState cluster state
+     * @return the settings for the specified project, or an empty settings object if no settings are found
+     */
     public static Settings getProjectSettings(ProjectId projectId, ClusterState clusterState) {
-        ProjectsStateRegistry registry = clusterState.custom(TYPE, EMPTY);
+        ProjectStateRegistry registry = clusterState.custom(TYPE, EMPTY);
         return registry.projectsSettings.getOrDefault(projectId, Settings.EMPTY);
     }
 
@@ -90,19 +101,12 @@ public int size() {
         return projectsSettings.size();
     }
 
-    /**
-     * Returns a new instance of ProjectsStateRegistry containing all projects from the cluster state and settings for the specified project
-     */
-    public static ProjectsStateRegistry setProjectSettings(ClusterState clusterState, ProjectId projectId, Settings settings) {
-        return ProjectsStateRegistry.builder(clusterState).putProjectSettings(projectId, settings).build();
-    }
-
     public static Builder builder(ClusterState original) {
-        ProjectsStateRegistry projectRegistry = original.custom(TYPE, EMPTY);
+        ProjectStateRegistry projectRegistry = original.custom(TYPE, EMPTY);
         return builder(projectRegistry);
     }
 
-    public static Builder builder(ProjectsStateRegistry projectRegistry) {
+    public static Builder builder(ProjectStateRegistry projectRegistry) {
         return new Builder(projectRegistry);
     }
 
@@ -117,7 +121,7 @@ private Builder() {
             this.projectsSettings = ImmutableOpenMap.builder();
         }
 
-        private Builder(ProjectsStateRegistry original) {
+        private Builder(ProjectStateRegistry original) {
             this.projectsSettings = ImmutableOpenMap.builder(original.projectsSettings);
         }
 
@@ -126,9 +130,8 @@ public Builder putProjectSettings(ProjectId projectId, Settings settings) {
             return this;
         }
 
-        public ProjectsStateRegistry build() {
-            return new ProjectsStateRegistry(projectsSettings.build());
+        public ProjectStateRegistry build() {
+            return new ProjectStateRegistry(projectsSettings.build());
         }
     }
-
 }

server/src/main/java/org/elasticsearch/reservedstate/service/ReservedProjectStateUpdateTask.java

@@ -14,7 +14,7 @@
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.metadata.ProjectId;
 import org.elasticsearch.cluster.metadata.ProjectMetadata;
-import org.elasticsearch.cluster.project.ProjectsStateRegistry;
+import org.elasticsearch.cluster.project.ProjectStateRegistry;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.gateway.GatewayService;
 import org.elasticsearch.reservedstate.ReservedProjectStateHandler;
@@ -73,10 +73,10 @@ protected ClusterState execute(ClusterState currentState) {
         }
 
         ClusterState updatedClusterState = result.v1();
-        Settings updatedSettings = ProjectsStateRegistry.getProjectSettings(projectId, updatedClusterState);
+        Settings updatedSettings = ProjectStateRegistry.getProjectSettings(projectId, updatedClusterState);
         ProjectMetadata updatedProject = updatedClusterState.getMetadata().getProject(projectId);
         return ClusterState.builder(currentState)
-            .putCustom(ProjectsStateRegistry.TYPE, ProjectsStateRegistry.setProjectSettings(currentState, projectId, updatedSettings))
+            .putCustom(ProjectStateRegistry.TYPE, ProjectStateRegistry.builder(currentState).putProjectSettings(projectId, updatedSettings).build())
             .putProjectMetadata(ProjectMetadata.builder(updatedProject).put(result.v2()))
             .build();
     }

server/src/test/java/org/elasticsearch/action/bulk/TransportBulkActionIngestTests.java

@@ -38,7 +38,7 @@
 import org.elasticsearch.cluster.metadata.Template;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
-import org.elasticsearch.cluster.project.ProjectsStateRegistry;
+import org.elasticsearch.cluster.project.ProjectStateRegistry;
 import org.elasticsearch.cluster.project.TestProjectResolvers;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.TriConsumer;
@@ -353,8 +353,8 @@ public void setupAction() {
         when(state.getMetadata()).thenReturn(metadata);
         when(state.metadata()).thenReturn(metadata);
         when(state.blocks()).thenReturn(mock(ClusterBlocks.class));
-        when(state.custom(eq(ProjectsStateRegistry.TYPE), any())).thenReturn(
-            ProjectsStateRegistry.builder().putProjectSettings(projectId, Settings.builder().build()).build()
+        when(state.custom(eq(ProjectStateRegistry.TYPE), any())).thenReturn(
+            ProjectStateRegistry.builder().putProjectSettings(projectId, Settings.builder().build()).build()
         );
         when(clusterService.state()).thenReturn(state);
         doAnswer(invocation -> {

server/src/test/java/org/elasticsearch/cluster/ClusterStateTests.java

@@ -29,7 +29,7 @@
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.node.DiscoveryNodeUtils;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
-import org.elasticsearch.cluster.project.ProjectsStateRegistry;
+import org.elasticsearch.cluster.project.ProjectStateRegistry;
 import org.elasticsearch.cluster.routing.GlobalRoutingTable;
 import org.elasticsearch.cluster.routing.GlobalRoutingTableTestHelper;
 import org.elasticsearch.cluster.routing.IndexRoutingTable;
@@ -921,8 +921,8 @@ private static ClusterState buildMultiProjectClusterState(DiscoveryNode... nodes
             .nodes(discoveryNodes.build())
             .routingTable(GlobalRoutingTableTestHelper.buildRoutingTable(metadata, RoutingTable.Builder::addAsNew))
             .putCustom(
-                ProjectsStateRegistry.TYPE,
-                ProjectsStateRegistry.builder()
+                ProjectStateRegistry.TYPE,
+                ProjectStateRegistry.builder()
                     .putProjectSettings(
                         projectId1,
                         Settings.builder().put(PROJECT_SETTING.getKey(), 42).put(PROJECT_SETTING2.getKey(), 43).build()
@@ -2225,8 +2225,8 @@ public static int expectedChunkCount(ToXContent.Params params, ClusterState clus
                     chunkCount += 2 + snapshotDeletionsInProgress.getEntries().size();
                 } else if (custom instanceof SnapshotsInProgress snapshotsInProgress) {
                     chunkCount += 2 + snapshotsInProgress.asStream().count();
-                } else if (custom instanceof ProjectsStateRegistry projectsStateRegistry) {
-                    chunkCount += 2 + projectsStateRegistry.size();
+                } else if (custom instanceof ProjectStateRegistry projectStateRegistry) {
+                    chunkCount += 2 + projectStateRegistry.size();
                 } else {
                     // could be anything, we have to just try it
                     chunkCount += Iterables.size(