package org.apache.helix.examples;
/*
* 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.UUID;
import org.apache.helix.ClusterMessagingService;
import org.apache.helix.Criteria;
import org.apache.helix.HelixManager;
import org.apache.helix.InstanceType;
import org.apache.helix.NotificationContext;
import org.apache.helix.api.id.MessageId;
import org.apache.helix.model.Message;
import org.apache.helix.model.Message.MessageState;
import org.apache.helix.model.Message.MessageType;
import org.apache.helix.participant.statemachine.StateModel;
import org.apache.helix.participant.statemachine.StateModelFactory;
import org.apache.helix.participant.statemachine.StateModelInfo;
import org.apache.helix.participant.statemachine.Transition;
public class BootstrapHandler extends StateModelFactory<StateModel> {
@Override
public StateModel createNewStateModel(String stateUnitKey) {
return new BootstrapStateModel(stateUnitKey);
}
@StateModelInfo(initialState = "OFFLINE", states = "{'OFFLINE','SLAVE','MASTER'}")
public static class BootstrapStateModel extends StateModel {
private final String _stateUnitKey;
public BootstrapStateModel(String stateUnitKey) {
_stateUnitKey = stateUnitKey;
}
@Transition(from = "MASTER", to = "SLAVE")
public void masterToSlave(Message message, NotificationContext context) {
}
@Transition(from = "OFFLINE", to = "SLAVE")
public void offlineToSlave(Message message, NotificationContext context) {
System.out.println("BootstrapProcess.BootstrapStateModel.offlineToSlave()");
HelixManager manager = context.getManager();
ClusterMessagingService messagingService = manager.getMessagingService();
Message requestBackupUriRequest =
new Message(MessageType.USER_DEFINE_MSG, MessageId.from(UUID.randomUUID().toString()));
requestBackupUriRequest.setMsgSubType(BootstrapProcess.REQUEST_BOOTSTRAP_URL);
requestBackupUriRequest.setMsgState(MessageState.NEW);
Criteria recipientCriteria = new Criteria();
recipientCriteria.setInstanceName("*");
recipientCriteria.setRecipientInstanceType(InstanceType.PARTICIPANT);
recipientCriteria.setResource(message.getResourceId().stringify());
recipientCriteria.setPartition(message.getPartitionId().stringify());
recipientCriteria.setSessionSpecific(true);
// wait for 30 seconds
int timeout = 30000;
BootstrapReplyHandler responseHandler = new BootstrapReplyHandler();
int sentMessageCount =
messagingService.sendAndWait(recipientCriteria, requestBackupUriRequest, responseHandler,
timeout);
if (sentMessageCount == 0) {
// could not find any other node hosting the partition
} else if (responseHandler.getBootstrapUrl() != null) {
System.out.println("Got bootstrap url:" + responseHandler.getBootstrapUrl());
System.out.println("Got backup time:" + responseHandler.getBootstrapTime());
// Got the url fetch it
} else {
// Either go to error state
// throw new Exception("Cant find backup/bootstrap data");
// Request some node to start backup process
}
}
@Transition(from = "SLAVE", to = "OFFLINE")
public void slaveToOffline(Message message, NotificationContext context) {
System.out.println("BootstrapProcess.BootstrapStateModel.slaveToOffline()");
}
@Transition(from = "SLAVE", to = "MASTER")
public void slaveToMaster(Message message, NotificationContext context) {
System.out.println("BootstrapProcess.BootstrapStateModel.slaveToMaster()");
}
}
}