helix-core/src/test/java/org/apache/helix/messaging/p2pMessage/TestP2PStateTransitionMessages.java - helix - Git at Google

 package org.apache.helix.messaging.p2pMessage;

 /*
  * 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.List;
 import java.util.Map;
 import java.util.concurrent.Executors;

 import org.apache.helix.HelixConstants;
 import org.apache.helix.controller.common.PartitionStateMap;
 import org.apache.helix.controller.dataproviders.ResourceControllerDataProvider;
 import org.apache.helix.controller.pipeline.Pipeline;
 import org.apache.helix.controller.stages.AttributeName;
 import org.apache.helix.controller.stages.BaseStageTest;
 import org.apache.helix.controller.stages.BestPossibleStateCalcStage;
 import org.apache.helix.controller.stages.BestPossibleStateOutput;
 import org.apache.helix.controller.stages.CurrentStateOutput;
 import org.apache.helix.controller.stages.IntermediateStateCalcStage;
 import org.apache.helix.controller.stages.MessageGenerationPhase;
 import org.apache.helix.controller.stages.MessageOutput;
 import org.apache.helix.controller.stages.MessageSelectionStage;
 import org.apache.helix.controller.stages.MessageThrottleStage;
 import org.apache.helix.controller.stages.ReadClusterDataStage;
 import org.apache.helix.model.BuiltInStateModelDefinitions;
 import org.apache.helix.model.ClusterConfig;
 import org.apache.helix.model.IdealState;
 import org.apache.helix.model.MasterSlaveSMD;
 import org.apache.helix.model.Message;
 import org.apache.helix.model.Partition;
 import org.apache.helix.model.Resource;
 import org.testng.Assert;
 import org.testng.annotations.Test;


 public class TestP2PStateTransitionMessages extends BaseStageTest {
   String db = "testDB";
   int numPartition = 1;
   int numReplica = 3;


   private void preSetup() {
     setupIdealState(3, new String[] { db }, numPartition, numReplica,
         IdealState.RebalanceMode.SEMI_AUTO, BuiltInStateModelDefinitions.MasterSlave.name());
     setupStateModel();
     setupInstances(3);
     setupLiveInstances(3);
   }

   @Test
   public void testP2PMessageEnabled() throws Exception {
     preSetup();
     ClusterConfig clusterConfig = new ClusterConfig(_clusterName);
     clusterConfig.enableP2PMessage(true);
     setClusterConfig(clusterConfig);

     testP2PMessage(clusterConfig, true);
   }

   @Test
   public void testP2PMessageDisabled() throws Exception {
     preSetup();
     testP2PMessage(null, false);
   }

   @Test
   public void testAvoidDuplicatedMessageWithP2PEnabled() throws Exception {
     preSetup();
     ClusterConfig clusterConfig = new ClusterConfig(_clusterName);
     clusterConfig.enableP2PMessage(true);
     setClusterConfig(clusterConfig);

     Map<String, Resource> resourceMap = getResourceMap(new String[] { db }, numPartition,
         BuiltInStateModelDefinitions.MasterSlave.name(), clusterConfig, null);

     ResourceControllerDataProvider cache = new ResourceControllerDataProvider();
     cache.setAsyncTasksThreadPool(Executors.newSingleThreadExecutor());
     event.addAttribute(AttributeName.ControllerDataProvider.name(), cache);
     event.addAttribute(AttributeName.RESOURCES.name(), resourceMap);
     event.addAttribute(AttributeName.RESOURCES_TO_REBALANCE.name(), resourceMap);
     event.addAttribute(AttributeName.CURRENT_STATE.name(), new CurrentStateOutput());
     event.addAttribute(AttributeName.helixmanager.name(), manager);

     Pipeline pipeline = createPipeline();
     pipeline.handle(event);

     BestPossibleStateOutput bestPossibleStateOutput =
         event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

     CurrentStateOutput currentStateOutput =
         populateCurrentStateFromBestPossible(bestPossibleStateOutput);
     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     Partition p = new Partition(db + "_0");

     String masterInstance = getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
         MasterSlaveSMD.States.MASTER.name());
     Assert.assertNotNull(masterInstance);

     admin.enableInstance(_clusterName, masterInstance, false);
     cache = event.getAttribute(AttributeName.ControllerDataProvider.name());
     cache.notifyDataChange(HelixConstants.ChangeType.INSTANCE_CONFIG);

     pipeline = createPipeline();
     pipeline.handle(event);

     bestPossibleStateOutput = event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

     MessageOutput messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     List<Message> messages = messageOutput.getMessages(db, p);

     Assert.assertEquals(messages.size(), 1);
     Message toSlaveMessage = messages.get(0);
     Assert.assertEquals(toSlaveMessage.getTgtName(), masterInstance);
     Assert.assertEquals(toSlaveMessage.getFromState(), MasterSlaveSMD.States.MASTER.name());
     Assert.assertEquals(toSlaveMessage.getToState(), MasterSlaveSMD.States.SLAVE.name());

     // verify p2p message sent to the old master instance
     Assert.assertEquals(toSlaveMessage.getRelayMessages().entrySet().size(), 1);
     String newMasterInstance =
         getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
             MasterSlaveSMD.States.MASTER.name());

     Message relayMessage = toSlaveMessage.getRelayMessage(newMasterInstance);
     Assert.assertNotNull(relayMessage);
     Assert.assertEquals(relayMessage.getMsgSubType(), Message.MessageType.RELAYED_MESSAGE.name());
     Assert.assertEquals(relayMessage.getTgtName(), newMasterInstance);
     Assert.assertEquals(relayMessage.getRelaySrcHost(), masterInstance);
     Assert.assertEquals(relayMessage.getFromState(), MasterSlaveSMD.States.SLAVE.name());
     Assert.assertEquals(relayMessage.getToState(), MasterSlaveSMD.States.MASTER.name());


     // test the old master finish state transition, but has not forward p2p message yet.
     currentStateOutput.setCurrentState(db, p, masterInstance, "SLAVE");
     currentStateOutput.setPendingMessage(db, p, masterInstance, toSlaveMessage);
     currentStateOutput.setPendingRelayMessage(db, p, masterInstance, relayMessage);

     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     pipeline.handle(event);

     messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     messages = messageOutput.getMessages(db, p);
     Assert.assertEquals(messages.size(), 0);


     currentStateOutput =
         populateCurrentStateFromBestPossible(bestPossibleStateOutput);
     currentStateOutput.setCurrentState(db, p, masterInstance, "SLAVE");
     currentStateOutput.setPendingMessage(db, p, newMasterInstance, relayMessage);
     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     pipeline.handle(event);

     messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     messages = messageOutput.getMessages(db, p);
     Assert.assertEquals(messages.size(), 1);

     Message toOfflineMessage = messages.get(0);
     Assert.assertEquals(toOfflineMessage.getTgtName(), masterInstance);
     Assert.assertEquals(toOfflineMessage.getFromState(), MasterSlaveSMD.States.SLAVE.name());
     Assert.assertEquals(toOfflineMessage.getToState(), MasterSlaveSMD.States.OFFLINE.name());


     // Now, the old master finish state transition, but has not forward p2p message yet.
     // Then the preference list has changed, so now the new master is different from previously calculated new master
     // but controller should not send S->M to newly calculated master.
     currentStateOutput.setCurrentState(db, p, masterInstance, "OFFLINE");
     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     String slaveInstance =
         getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
             MasterSlaveSMD.States.SLAVE.name());

     Map<String, String> instanceStateMap = bestPossibleStateOutput.getInstanceStateMap(db, p);
     instanceStateMap.put(newMasterInstance, "SLAVE");
     instanceStateMap.put(slaveInstance, "MASTER");
     bestPossibleStateOutput.setState(db, p, instanceStateMap);

     event.addAttribute(AttributeName.BEST_POSSIBLE_STATE.name(), bestPossibleStateOutput);

     pipeline = new Pipeline("test");
     pipeline.addStage(new MessageGenerationPhase());
     pipeline.addStage(new MessageSelectionStage());
     pipeline.addStage(new IntermediateStateCalcStage());
     pipeline.addStage(new MessageThrottleStage());

     pipeline.handle(event);

     messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     messages = messageOutput.getMessages(db, p);
     Assert.assertEquals(messages.size(), 0);


     // Now, the old master has forwarded the p2p master to previously calculated master,
     // So the state-transition still happened in previously calculated master.
     // Controller will not send S->M to new master.
     currentStateOutput.setPendingMessage(db, p, newMasterInstance, relayMessage);
     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     event.addAttribute(AttributeName.BEST_POSSIBLE_STATE.name(), bestPossibleStateOutput);
     event.addAttribute(AttributeName.INTERMEDIATE_STATE.name(), bestPossibleStateOutput);


     pipeline = new Pipeline("test");
     pipeline.addStage(new MessageGenerationPhase());
     pipeline.addStage(new MessageSelectionStage());
     pipeline.addStage(new IntermediateStateCalcStage());
     pipeline.addStage(new MessageThrottleStage());

     pipeline.handle(event);

     messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     messages = messageOutput.getMessages(db, p);
     Assert.assertEquals(messages.size(), 0);


     // now, the previous calculated master completed the state transition and deleted the p2p message.
     // Controller should drop this master first.
     currentStateOutput =
         populateCurrentStateFromBestPossible(bestPossibleStateOutput);
     currentStateOutput.setCurrentState(db, p, newMasterInstance, "MASTER");
     currentStateOutput.setCurrentState(db, p, slaveInstance, "SLAVE");

     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     pipeline = new Pipeline("test");
     pipeline.addStage(new MessageGenerationPhase());
     pipeline.addStage(new MessageSelectionStage());
     pipeline.addStage(new MessageThrottleStage());

     pipeline.handle(event);

     messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     messages = messageOutput.getMessages(db, p);
     Assert.assertEquals(messages.size(), 1);

     toSlaveMessage = messages.get(0);
     Assert.assertEquals(toSlaveMessage.getTgtName(), newMasterInstance);
     Assert.assertEquals(toSlaveMessage.getFromState(), MasterSlaveSMD.States.MASTER.name());
     Assert.assertEquals(toSlaveMessage.getToState(), MasterSlaveSMD.States.SLAVE.name());
   }

   private void testP2PMessage(ClusterConfig clusterConfig, Boolean p2pMessageEnabled)
       throws Exception {
     Map<String, Resource> resourceMap = getResourceMap(new String[] { db }, numPartition,
         BuiltInStateModelDefinitions.MasterSlave.name(), clusterConfig, null);

     event.addAttribute(AttributeName.RESOURCES.name(), resourceMap);
     event.addAttribute(AttributeName.RESOURCES_TO_REBALANCE.name(), resourceMap);
     event.addAttribute(AttributeName.CURRENT_STATE.name(), new CurrentStateOutput());
     event.addAttribute(AttributeName.helixmanager.name(), manager);
     event.addAttribute(AttributeName.ControllerDataProvider.name(),
         new ResourceControllerDataProvider());

     Pipeline pipeline = createPipeline();
     pipeline.handle(event);

     BestPossibleStateOutput bestPossibleStateOutput =
         event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

     CurrentStateOutput currentStateOutput =
         populateCurrentStateFromBestPossible(bestPossibleStateOutput);
     event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

     Partition p = new Partition(db + "_0");

     String masterInstance = getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
         MasterSlaveSMD.States.MASTER.name());
     Assert.assertNotNull(masterInstance);

     admin.enableInstance(_clusterName, masterInstance, false);
     ResourceControllerDataProvider cache = event.getAttribute(AttributeName.ControllerDataProvider.name());
     cache.notifyDataChange(HelixConstants.ChangeType.INSTANCE_CONFIG);

     pipeline = createPipeline();
     pipeline.handle(event);

     bestPossibleStateOutput = event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

     MessageOutput messageOutput =
         event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
     List<Message> messages = messageOutput.getMessages(db, p);

     Assert.assertEquals(messages.size(), 1);
     Message message = messages.get(0);
     Assert.assertEquals(message.getTgtName(), masterInstance);
     Assert.assertEquals(message.getFromState(), MasterSlaveSMD.States.MASTER.name());
     Assert.assertEquals(message.getToState(), MasterSlaveSMD.States.SLAVE.name());

     if (p2pMessageEnabled) {
       Assert.assertEquals(message.getRelayMessages().entrySet().size(), 1);
       String newMasterInstance =
           getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
               MasterSlaveSMD.States.MASTER.name());

       Message relayMessage = message.getRelayMessage(newMasterInstance);
       Assert.assertNotNull(relayMessage);
       Assert.assertEquals(relayMessage.getMsgSubType(), Message.MessageType.RELAYED_MESSAGE.name());
       Assert.assertEquals(relayMessage.getTgtName(), newMasterInstance);
       Assert.assertEquals(relayMessage.getRelaySrcHost(), masterInstance);
       Assert.assertEquals(relayMessage.getFromState(), MasterSlaveSMD.States.SLAVE.name());
       Assert.assertEquals(relayMessage.getToState(), MasterSlaveSMD.States.MASTER.name());
     } else {
       Assert.assertTrue(message.getRelayMessages().entrySet().isEmpty());
     }
   }

   private String getTopStateInstance(Map<String, String> instanceStateMap, String topState) {
     String masterInstance = null;
     for (Map.Entry<String, String> e : instanceStateMap.entrySet()) {
       if (topState.equals(e.getValue())) {
         masterInstance = e.getKey();
       }
     }

     return masterInstance;
   }

   private CurrentStateOutput populateCurrentStateFromBestPossible(
       BestPossibleStateOutput bestPossibleStateOutput) {
     CurrentStateOutput currentStateOutput = new CurrentStateOutput();
     for (String resource : bestPossibleStateOutput.getResourceStatesMap().keySet()) {
       PartitionStateMap partitionStateMap = bestPossibleStateOutput.getPartitionStateMap(resource);
       for (Partition p : partitionStateMap.partitionSet()) {
         Map<String, String> stateMap = partitionStateMap.getPartitionMap(p);

         for (Map.Entry<String, String> e : stateMap.entrySet()) {
           currentStateOutput.setCurrentState(resource, p, e.getKey(), e.getValue());
         }
       }
     }
     return currentStateOutput;
   }

   private Pipeline createPipeline() {
     Pipeline pipeline = new Pipeline("test");
     pipeline.addStage(new ReadClusterDataStage());
     pipeline.addStage(new BestPossibleStateCalcStage());
     pipeline.addStage(new MessageGenerationPhase());
     pipeline.addStage(new MessageSelectionStage());
     pipeline.addStage(new IntermediateStateCalcStage());
     pipeline.addStage(new MessageThrottleStage());

     return pipeline;
   }
 }
	package org.apache.helix.messaging.p2pMessage;

	/*
	* 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.List;
	import java.util.Map;
	import java.util.concurrent.Executors;

	import org.apache.helix.HelixConstants;
	import org.apache.helix.controller.common.PartitionStateMap;
	import org.apache.helix.controller.dataproviders.ResourceControllerDataProvider;
	import org.apache.helix.controller.pipeline.Pipeline;
	import org.apache.helix.controller.stages.AttributeName;
	import org.apache.helix.controller.stages.BaseStageTest;
	import org.apache.helix.controller.stages.BestPossibleStateCalcStage;
	import org.apache.helix.controller.stages.BestPossibleStateOutput;
	import org.apache.helix.controller.stages.CurrentStateOutput;
	import org.apache.helix.controller.stages.IntermediateStateCalcStage;
	import org.apache.helix.controller.stages.MessageGenerationPhase;
	import org.apache.helix.controller.stages.MessageOutput;
	import org.apache.helix.controller.stages.MessageSelectionStage;
	import org.apache.helix.controller.stages.MessageThrottleStage;
	import org.apache.helix.controller.stages.ReadClusterDataStage;
	import org.apache.helix.model.BuiltInStateModelDefinitions;
	import org.apache.helix.model.ClusterConfig;
	import org.apache.helix.model.IdealState;
	import org.apache.helix.model.MasterSlaveSMD;
	import org.apache.helix.model.Message;
	import org.apache.helix.model.Partition;
	import org.apache.helix.model.Resource;
	import org.testng.Assert;
	import org.testng.annotations.Test;


	public class TestP2PStateTransitionMessages extends BaseStageTest {
	String db = "testDB";
	int numPartition = 1;
	int numReplica = 3;


	private void preSetup() {
	setupIdealState(3, new String[] { db }, numPartition, numReplica,
	IdealState.RebalanceMode.SEMI_AUTO, BuiltInStateModelDefinitions.MasterSlave.name());
	setupStateModel();
	setupInstances(3);
	setupLiveInstances(3);
	}

	@Test
	public void testP2PMessageEnabled() throws Exception {
	preSetup();
	ClusterConfig clusterConfig = new ClusterConfig(_clusterName);
	clusterConfig.enableP2PMessage(true);
	setClusterConfig(clusterConfig);

	testP2PMessage(clusterConfig, true);
	}

	@Test
	public void testP2PMessageDisabled() throws Exception {
	preSetup();
	testP2PMessage(null, false);
	}

	@Test
	public void testAvoidDuplicatedMessageWithP2PEnabled() throws Exception {
	preSetup();
	ClusterConfig clusterConfig = new ClusterConfig(_clusterName);
	clusterConfig.enableP2PMessage(true);
	setClusterConfig(clusterConfig);

	Map<String, Resource> resourceMap = getResourceMap(new String[] { db }, numPartition,
	BuiltInStateModelDefinitions.MasterSlave.name(), clusterConfig, null);

	ResourceControllerDataProvider cache = new ResourceControllerDataProvider();
	cache.setAsyncTasksThreadPool(Executors.newSingleThreadExecutor());
	event.addAttribute(AttributeName.ControllerDataProvider.name(), cache);
	event.addAttribute(AttributeName.RESOURCES.name(), resourceMap);
	event.addAttribute(AttributeName.RESOURCES_TO_REBALANCE.name(), resourceMap);
	event.addAttribute(AttributeName.CURRENT_STATE.name(), new CurrentStateOutput());
	event.addAttribute(AttributeName.helixmanager.name(), manager);

	Pipeline pipeline = createPipeline();
	pipeline.handle(event);

	BestPossibleStateOutput bestPossibleStateOutput =
	event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

	CurrentStateOutput currentStateOutput =
	populateCurrentStateFromBestPossible(bestPossibleStateOutput);
	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	Partition p = new Partition(db + "_0");

	String masterInstance = getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
	MasterSlaveSMD.States.MASTER.name());
	Assert.assertNotNull(masterInstance);

	admin.enableInstance(_clusterName, masterInstance, false);
	cache = event.getAttribute(AttributeName.ControllerDataProvider.name());
	cache.notifyDataChange(HelixConstants.ChangeType.INSTANCE_CONFIG);

	pipeline = createPipeline();
	pipeline.handle(event);

	bestPossibleStateOutput = event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

	MessageOutput messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	List<Message> messages = messageOutput.getMessages(db, p);

	Assert.assertEquals(messages.size(), 1);
	Message toSlaveMessage = messages.get(0);
	Assert.assertEquals(toSlaveMessage.getTgtName(), masterInstance);
	Assert.assertEquals(toSlaveMessage.getFromState(), MasterSlaveSMD.States.MASTER.name());
	Assert.assertEquals(toSlaveMessage.getToState(), MasterSlaveSMD.States.SLAVE.name());

	// verify p2p message sent to the old master instance
	Assert.assertEquals(toSlaveMessage.getRelayMessages().entrySet().size(), 1);
	String newMasterInstance =
	getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
	MasterSlaveSMD.States.MASTER.name());

	Message relayMessage = toSlaveMessage.getRelayMessage(newMasterInstance);
	Assert.assertNotNull(relayMessage);
	Assert.assertEquals(relayMessage.getMsgSubType(), Message.MessageType.RELAYED_MESSAGE.name());
	Assert.assertEquals(relayMessage.getTgtName(), newMasterInstance);
	Assert.assertEquals(relayMessage.getRelaySrcHost(), masterInstance);
	Assert.assertEquals(relayMessage.getFromState(), MasterSlaveSMD.States.SLAVE.name());
	Assert.assertEquals(relayMessage.getToState(), MasterSlaveSMD.States.MASTER.name());


	// test the old master finish state transition, but has not forward p2p message yet.
	currentStateOutput.setCurrentState(db, p, masterInstance, "SLAVE");
	currentStateOutput.setPendingMessage(db, p, masterInstance, toSlaveMessage);
	currentStateOutput.setPendingRelayMessage(db, p, masterInstance, relayMessage);

	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	pipeline.handle(event);

	messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	messages = messageOutput.getMessages(db, p);
	Assert.assertEquals(messages.size(), 0);


	currentStateOutput =
	populateCurrentStateFromBestPossible(bestPossibleStateOutput);
	currentStateOutput.setCurrentState(db, p, masterInstance, "SLAVE");
	currentStateOutput.setPendingMessage(db, p, newMasterInstance, relayMessage);
	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	pipeline.handle(event);

	messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	messages = messageOutput.getMessages(db, p);
	Assert.assertEquals(messages.size(), 1);

	Message toOfflineMessage = messages.get(0);
	Assert.assertEquals(toOfflineMessage.getTgtName(), masterInstance);
	Assert.assertEquals(toOfflineMessage.getFromState(), MasterSlaveSMD.States.SLAVE.name());
	Assert.assertEquals(toOfflineMessage.getToState(), MasterSlaveSMD.States.OFFLINE.name());


	// Now, the old master finish state transition, but has not forward p2p message yet.
	// Then the preference list has changed, so now the new master is different from previously calculated new master
	// but controller should not send S->M to newly calculated master.
	currentStateOutput.setCurrentState(db, p, masterInstance, "OFFLINE");
	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	String slaveInstance =
	getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
	MasterSlaveSMD.States.SLAVE.name());

	Map<String, String> instanceStateMap = bestPossibleStateOutput.getInstanceStateMap(db, p);
	instanceStateMap.put(newMasterInstance, "SLAVE");
	instanceStateMap.put(slaveInstance, "MASTER");
	bestPossibleStateOutput.setState(db, p, instanceStateMap);

	event.addAttribute(AttributeName.BEST_POSSIBLE_STATE.name(), bestPossibleStateOutput);

	pipeline = new Pipeline("test");
	pipeline.addStage(new MessageGenerationPhase());
	pipeline.addStage(new MessageSelectionStage());
	pipeline.addStage(new IntermediateStateCalcStage());
	pipeline.addStage(new MessageThrottleStage());

	pipeline.handle(event);

	messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	messages = messageOutput.getMessages(db, p);
	Assert.assertEquals(messages.size(), 0);


	// Now, the old master has forwarded the p2p master to previously calculated master,
	// So the state-transition still happened in previously calculated master.
	// Controller will not send S->M to new master.
	currentStateOutput.setPendingMessage(db, p, newMasterInstance, relayMessage);
	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	event.addAttribute(AttributeName.BEST_POSSIBLE_STATE.name(), bestPossibleStateOutput);
	event.addAttribute(AttributeName.INTERMEDIATE_STATE.name(), bestPossibleStateOutput);


	pipeline = new Pipeline("test");
	pipeline.addStage(new MessageGenerationPhase());
	pipeline.addStage(new MessageSelectionStage());
	pipeline.addStage(new IntermediateStateCalcStage());
	pipeline.addStage(new MessageThrottleStage());

	pipeline.handle(event);

	messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	messages = messageOutput.getMessages(db, p);
	Assert.assertEquals(messages.size(), 0);


	// now, the previous calculated master completed the state transition and deleted the p2p message.
	// Controller should drop this master first.
	currentStateOutput =
	populateCurrentStateFromBestPossible(bestPossibleStateOutput);
	currentStateOutput.setCurrentState(db, p, newMasterInstance, "MASTER");
	currentStateOutput.setCurrentState(db, p, slaveInstance, "SLAVE");

	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	pipeline = new Pipeline("test");
	pipeline.addStage(new MessageGenerationPhase());
	pipeline.addStage(new MessageSelectionStage());
	pipeline.addStage(new MessageThrottleStage());

	pipeline.handle(event);

	messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	messages = messageOutput.getMessages(db, p);
	Assert.assertEquals(messages.size(), 1);

	toSlaveMessage = messages.get(0);
	Assert.assertEquals(toSlaveMessage.getTgtName(), newMasterInstance);
	Assert.assertEquals(toSlaveMessage.getFromState(), MasterSlaveSMD.States.MASTER.name());
	Assert.assertEquals(toSlaveMessage.getToState(), MasterSlaveSMD.States.SLAVE.name());
	}

	private void testP2PMessage(ClusterConfig clusterConfig, Boolean p2pMessageEnabled)
	throws Exception {
	Map<String, Resource> resourceMap = getResourceMap(new String[] { db }, numPartition,
	BuiltInStateModelDefinitions.MasterSlave.name(), clusterConfig, null);

	event.addAttribute(AttributeName.RESOURCES.name(), resourceMap);
	event.addAttribute(AttributeName.RESOURCES_TO_REBALANCE.name(), resourceMap);
	event.addAttribute(AttributeName.CURRENT_STATE.name(), new CurrentStateOutput());
	event.addAttribute(AttributeName.helixmanager.name(), manager);
	event.addAttribute(AttributeName.ControllerDataProvider.name(),
	new ResourceControllerDataProvider());

	Pipeline pipeline = createPipeline();
	pipeline.handle(event);

	BestPossibleStateOutput bestPossibleStateOutput =
	event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

	CurrentStateOutput currentStateOutput =
	populateCurrentStateFromBestPossible(bestPossibleStateOutput);
	event.addAttribute(AttributeName.CURRENT_STATE.name(), currentStateOutput);

	Partition p = new Partition(db + "_0");

	String masterInstance = getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
	MasterSlaveSMD.States.MASTER.name());
	Assert.assertNotNull(masterInstance);

	admin.enableInstance(_clusterName, masterInstance, false);
	ResourceControllerDataProvider cache = event.getAttribute(AttributeName.ControllerDataProvider.name());
	cache.notifyDataChange(HelixConstants.ChangeType.INSTANCE_CONFIG);

	pipeline = createPipeline();
	pipeline.handle(event);

	bestPossibleStateOutput = event.getAttribute(AttributeName.BEST_POSSIBLE_STATE.name());

	MessageOutput messageOutput =
	event.getAttribute(AttributeName.MESSAGES_SELECTED.name());
	List<Message> messages = messageOutput.getMessages(db, p);

	Assert.assertEquals(messages.size(), 1);
	Message message = messages.get(0);
	Assert.assertEquals(message.getTgtName(), masterInstance);
	Assert.assertEquals(message.getFromState(), MasterSlaveSMD.States.MASTER.name());
	Assert.assertEquals(message.getToState(), MasterSlaveSMD.States.SLAVE.name());

	if (p2pMessageEnabled) {
	Assert.assertEquals(message.getRelayMessages().entrySet().size(), 1);
	String newMasterInstance =
	getTopStateInstance(bestPossibleStateOutput.getInstanceStateMap(db, p),
	MasterSlaveSMD.States.MASTER.name());

	Message relayMessage = message.getRelayMessage(newMasterInstance);
	Assert.assertNotNull(relayMessage);
	Assert.assertEquals(relayMessage.getMsgSubType(), Message.MessageType.RELAYED_MESSAGE.name());
	Assert.assertEquals(relayMessage.getTgtName(), newMasterInstance);
	Assert.assertEquals(relayMessage.getRelaySrcHost(), masterInstance);
	Assert.assertEquals(relayMessage.getFromState(), MasterSlaveSMD.States.SLAVE.name());
	Assert.assertEquals(relayMessage.getToState(), MasterSlaveSMD.States.MASTER.name());
	} else {
	Assert.assertTrue(message.getRelayMessages().entrySet().isEmpty());
	}
	}

	private String getTopStateInstance(Map<String, String> instanceStateMap, String topState) {
	String masterInstance = null;
	for (Map.Entry<String, String> e : instanceStateMap.entrySet()) {
	if (topState.equals(e.getValue())) {
	masterInstance = e.getKey();
	}
	}

	return masterInstance;
	}

	private CurrentStateOutput populateCurrentStateFromBestPossible(
	BestPossibleStateOutput bestPossibleStateOutput) {
	CurrentStateOutput currentStateOutput = new CurrentStateOutput();
	for (String resource : bestPossibleStateOutput.getResourceStatesMap().keySet()) {
	PartitionStateMap partitionStateMap = bestPossibleStateOutput.getPartitionStateMap(resource);
	for (Partition p : partitionStateMap.partitionSet()) {
	Map<String, String> stateMap = partitionStateMap.getPartitionMap(p);

	for (Map.Entry<String, String> e : stateMap.entrySet()) {
	currentStateOutput.setCurrentState(resource, p, e.getKey(), e.getValue());
	}
	}
	}
	return currentStateOutput;
	}

	private Pipeline createPipeline() {
	Pipeline pipeline = new Pipeline("test");
	pipeline.addStage(new ReadClusterDataStage());
	pipeline.addStage(new BestPossibleStateCalcStage());
	pipeline.addStage(new MessageGenerationPhase());
	pipeline.addStage(new MessageSelectionStage());
	pipeline.addStage(new IntermediateStateCalcStage());
	pipeline.addStage(new MessageThrottleStage());

	return pipeline;
	}
	}