| /** |
| * 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.atlas.web.service; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.inject.Singleton; |
| import org.apache.atlas.ApplicationProperties; |
| import org.apache.atlas.AtlasException; |
| import org.apache.atlas.ha.HAConfiguration; |
| import org.apache.commons.configuration.Configuration; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * A class that maintains the state of this instance. |
| * |
| * The states are maintained at a granular level, including in-transition states. The transitions are |
| * directed by {@link ActiveInstanceElectorService}. |
| */ |
| @Singleton |
| public class ServiceState { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(ServiceState.class); |
| |
| public enum ServiceStateValue { |
| ACTIVE, |
| PASSIVE, |
| BECOMING_ACTIVE, |
| BECOMING_PASSIVE |
| } |
| |
| private Configuration configuration; |
| private volatile ServiceStateValue state; |
| |
| public ServiceState() throws AtlasException { |
| this(ApplicationProperties.get()); |
| } |
| |
| public ServiceState(Configuration configuration) { |
| this.configuration = configuration; |
| state = !HAConfiguration.isHAEnabled(configuration) ? |
| ServiceStateValue.ACTIVE : ServiceStateValue.PASSIVE; |
| } |
| |
| public ServiceStateValue getState() { |
| return state; |
| } |
| |
| public void becomingActive() { |
| LOG.warn("Instance becoming active from {}", state); |
| setState(ServiceStateValue.BECOMING_ACTIVE); |
| } |
| |
| private void setState(ServiceStateValue newState) { |
| Preconditions.checkState(HAConfiguration.isHAEnabled(configuration), |
| "Cannot change state as requested, as HA is not enabled for this instance."); |
| state = newState; |
| } |
| |
| public void setActive() { |
| LOG.warn("Instance is active from {}", state); |
| setState(ServiceStateValue.ACTIVE); |
| } |
| |
| public void becomingPassive() { |
| LOG.warn("Instance becoming passive from {}", state); |
| setState(ServiceStateValue.BECOMING_PASSIVE); |
| } |
| |
| public void setPassive() { |
| LOG.warn("Instance is passive from {}", state); |
| setState(ServiceStateValue.PASSIVE); |
| } |
| |
| public boolean isInstanceInTransition() { |
| ServiceStateValue state = getState(); |
| return state == ServiceStateValue.BECOMING_ACTIVE |
| || state == ServiceStateValue.BECOMING_PASSIVE; |
| } |
| } |