| /** |
| * 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. |
| */ |
| package org.apache.hadoop.ha; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.fs.CommonConfigurationKeys; |
| import org.apache.hadoop.io.retry.Idempotent; |
| import org.apache.hadoop.security.AccessControlException; |
| import org.apache.hadoop.security.KerberosInfo; |
| |
| import java.io.IOException; |
| |
| /** |
| * Protocol interface that provides High Availability related primitives to |
| * monitor and fail-over the service. |
| * |
| * This interface could be used by HA frameworks to manage the service. |
| */ |
| @KerberosInfo( |
| serverPrincipal=CommonConfigurationKeys.HADOOP_SECURITY_SERVICE_USER_NAME_KEY) |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public interface HAServiceProtocol { |
| /** |
| * Initial version of the protocol |
| */ |
| public static final long versionID = 1L; |
| |
| /** |
| * An HA service may be in active or standby state. During startup, it is in |
| * an unknown INITIALIZING state. During shutdown, it is in the STOPPING state |
| * and can no longer return to active/standby states. |
| */ |
| public enum HAServiceState { |
| INITIALIZING("initializing"), |
| ACTIVE("active"), |
| STANDBY("standby"), |
| STOPPING("stopping"); |
| |
| private String name; |
| |
| HAServiceState(String name) { |
| this.name = name; |
| } |
| |
| @Override |
| public String toString() { |
| return name; |
| } |
| } |
| |
| public static enum RequestSource { |
| REQUEST_BY_USER, |
| REQUEST_BY_USER_FORCED, |
| REQUEST_BY_ZKFC; |
| } |
| |
| /** |
| * Information describing the source for a request to change state. |
| * This is used to differentiate requests from automatic vs CLI |
| * failover controllers, and in the future may include epoch |
| * information. |
| */ |
| public static class StateChangeRequestInfo { |
| private final RequestSource source; |
| |
| public StateChangeRequestInfo(RequestSource source) { |
| super(); |
| this.source = source; |
| } |
| |
| public RequestSource getSource() { |
| return source; |
| } |
| } |
| |
| /** |
| * Monitor the health of service. This periodically called by the HA |
| * frameworks to monitor the health of the service. |
| * |
| * Service is expected to perform checks to ensure it is functional. |
| * If the service is not healthy due to failure or partial failure, |
| * it is expected to throw {@link HealthCheckFailedException}. |
| * The definition of service not healthy is left to the service. |
| * |
| * Note that when health check of an Active service fails, |
| * failover to standby may be done. |
| * |
| * @throws HealthCheckFailedException |
| * if the health check of a service fails. |
| * @throws AccessControlException |
| * if access is denied. |
| * @throws IOException |
| * if other errors happen |
| */ |
| @Idempotent |
| public void monitorHealth() throws HealthCheckFailedException, |
| AccessControlException, |
| IOException; |
| |
| /** |
| * Request service to transition to active state. No operation, if the |
| * service is already in active state. |
| * |
| * @throws ServiceFailedException |
| * if transition from standby to active fails. |
| * @throws AccessControlException |
| * if access is denied. |
| * @throws IOException |
| * if other errors happen |
| */ |
| @Idempotent |
| public void transitionToActive(StateChangeRequestInfo reqInfo) |
| throws ServiceFailedException, |
| AccessControlException, |
| IOException; |
| |
| /** |
| * Request service to transition to standby state. No operation, if the |
| * service is already in standby state. |
| * |
| * @throws ServiceFailedException |
| * if transition from active to standby fails. |
| * @throws AccessControlException |
| * if access is denied. |
| * @throws IOException |
| * if other errors happen |
| */ |
| @Idempotent |
| public void transitionToStandby(StateChangeRequestInfo reqInfo) |
| throws ServiceFailedException, |
| AccessControlException, |
| IOException; |
| |
| /** |
| * Return the current status of the service. The status indicates |
| * the current <em>state</em> (e.g ACTIVE/STANDBY) as well as |
| * some additional information. |
| * |
| * @throws AccessControlException |
| * if access is denied. |
| * @throws IOException |
| * if other errors happen |
| * @see HAServiceStatus |
| */ |
| @Idempotent |
| public HAServiceStatus getServiceStatus() throws AccessControlException, |
| IOException; |
| } |