Enable updating EV configs on IS updates

helix-core/src/main/java/org/apache/helix/controller/GenericHelixController.java

@@ -554,7 +554,7 @@ private static PipelineRegistry createDefaultRegistry(String pipelineName) {
       autoExitMaintenancePipeline.addStage(new MaintenanceRecoveryStage());
 
       registry.register(ClusterEventType.IdealStateChange, dataRefresh, dataPreprocess,
-          rebalancePipeline);
+          rebalancePipeline, externalViewPipeline);
       registry.register(ClusterEventType.CurrentStateChange, dataRefresh, dataPreprocess,
           externalViewPipeline, rebalancePipeline);
       registry.register(ClusterEventType.InstanceConfigChange, dataRefresh, dataPreprocess,

helix-core/src/test/java/org/apache/helix/controller/stages/TestExternalViewComputeOnIdealStateChange.java

@@ -0,0 +1,141 @@
+package org.apache.helix.controller.stages;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.util.Map;
+
+import java.util.Objects;
+import org.apache.helix.PropertyKey.Builder;
+import org.apache.helix.controller.dataproviders.ResourceControllerDataProvider;
+import org.apache.helix.model.ExternalView;
+import org.apache.helix.model.IdealState;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+/**
+ * Test to verify that ExternalViewComputeStage on IdealStateChange events only copies
+ * simple fields  and not partition assignments from IdealState to ExternalView.
+ */
+public class TestExternalViewComputeOnIdealStateChange extends BaseStageTest {
+
+  @Test
+  public void testExternalViewComputeOnlySimpleFieldsFromIdealState() throws InterruptedException {
+    String resourceName = "TestDB";
+    String partition1 = resourceName + "_0";
+    String partition2 = resourceName + "_1";
+    String instance1 = "localhost_1001";
+    String instance2 = "localhost_1002";
+    String instance3 = "localhost_1003";
+
+    setupStateModel();
+
+    // create initial IdealState
+    IdealState idealState = new IdealState(resourceName);
+    idealState.setStateModelDefRef("MasterSlave");
+    idealState.setRebalanceMode(IdealState.RebalanceMode.SEMI_AUTO);
+    idealState.setNumPartitions(2);
+    idealState.setReplicas("2");
+    idealState.setMinActiveReplicas(1);
+
+    // Set initial simple field config
+    idealState.getRecord().setSimpleField("CUSTOM_CONFIG_KEY", "initial_value");
+    idealState.getRecord().setSimpleField("CUSTOM_TIMEOUT", "5000");
+
+    // Set initial partition assignments in IdealState
+    idealState.setPartitionState(partition1, instance1, "MASTER");
+    idealState.setPartitionState(partition1, instance2, "SLAVE");
+    idealState.setPartitionState(partition2, instance2, "MASTER");
+    idealState.setPartitionState(partition2, instance3, "SLAVE");
+
+    setSingleIdealState(idealState);
+
+    // run pipeline stages to setup the environment
+    ClusterEvent event = new ClusterEvent(_clusterName, ClusterEventType.IdealStateChange);
+    ResourceControllerDataProvider cache = new ResourceControllerDataProvider(_clusterName);
+    event.addAttribute(AttributeName.ControllerDataProvider.name(), cache);
+    event.addAttribute(AttributeName.helixmanager.name(), manager);
+
+    runStage(event, new ReadClusterDataStage());
+    runStage(event, new ResourceComputationStage());
+    runStage(event, new CurrentStateComputationStage());
+    runStage(event, new ExternalViewComputeStage());
+
+    Builder keyBuilder = accessor.keyBuilder();
+
+    // update IdealState
+    IdealState updatedIdealState = new IdealState(resourceName);
+    updatedIdealState.setStateModelDefRef("MasterSlave");
+    updatedIdealState.setRebalanceMode(IdealState.RebalanceMode.SEMI_AUTO);
+    updatedIdealState.setNumPartitions(2);
+    updatedIdealState.setReplicas("2");
+    updatedIdealState.setMinActiveReplicas(1);
+
+    // Update simple field config, this should get copied to ExternalView
+    updatedIdealState.getRecord().setSimpleField("CUSTOM_CONFIG_KEY", "updated_value");
+    updatedIdealState.getRecord().setSimpleField("CUSTOM_TIMEOUT", "10000");
+    updatedIdealState.getRecord().setSimpleField("NEW_CONFIG", "new_config_value");
+
+    // Update partition assignments, this shouldn't get copied to ExternalView
+    updatedIdealState.setPartitionState(partition1, instance3, "MASTER");
+    updatedIdealState.setPartitionState(partition1, instance1, "SLAVE");
+    updatedIdealState.setPartitionState(partition2, instance1, "MASTER");
+    updatedIdealState.setPartitionState(partition2, instance2, "SLAVE");
+
+    setSingleIdealState(updatedIdealState);
+
+    cache = new ResourceControllerDataProvider(_clusterName);
+    event.addAttribute(AttributeName.ControllerDataProvider.name(), cache);
+
+    // Re-run all stages with new cache to ensure it has both updated IdealState and current state
+    runStage(event, new ReadClusterDataStage());
+    runStage(event, new ResourceComputationStage());
+    runStage(event, new CurrentStateComputationStage());
+    runStage(event, new ExternalViewComputeStage());
+
+    // verify results
+    ExternalView updatedEV = accessor.getProperty(keyBuilder.externalView(resourceName));
+    System.out.println("Updated ExternalView simple fields: " + updatedEV.getRecord().getSimpleFields());
+    Assert.assertNotNull(updatedEV, "ExternalView should exist after running ExternalViewComputeStage");
+
+    Assert.assertEquals(updatedEV.getRecord().getSimpleField("CUSTOM_CONFIG_KEY"), "updated_value",
+        "Simple field CUSTOM_CONFIG_KEY should be copied from IdealState");
+    Assert.assertEquals(updatedEV.getRecord().getSimpleField("CUSTOM_TIMEOUT"), "10000",
+        "Simple field CUSTOM_TIMEOUT should be copied from IdealState");
+    Assert.assertEquals(updatedEV.getRecord().getSimpleField("NEW_CONFIG"), "new_config_value",
+        "New simple field NEW_CONFIG should be copied from IdealState");
+
+    Map<String, String> finalPartition1States = updatedEV.getStateMap(partition1);
+    Map<String, String> finalPartition2States = updatedEV.getStateMap(partition2);
+
+    Map<String, String> idealStatePartition1 = updatedIdealState.getInstanceStateMap(partition1);
+    Map<String, String> idealStatePartition2 = updatedIdealState.getInstanceStateMap(partition2);
+
+    // verify partition assignments are not equal to IdealState assignments
+    Assert.assertFalse(
+        Objects.equals(finalPartition1States, idealStatePartition1),
+        "Final EV partition1 assignments should NOT match updated IdealState assignments"
+    );
+    Assert.assertFalse(
+        Objects.equals(finalPartition2States, idealStatePartition2),
+        "Final EV partition2 assignments should NOT match updated IdealState assignments"
+    );
+
+  }
+}