org.apache.hadoop.yarn.server.resourcemanager.recovery.RMStateStore.java Source code

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/**
* 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.yarn.server.resourcemanager.recovery;

import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;
import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;

import javax.crypto.SecretKey;

import com.google.common.annotations.VisibleForTesting;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.classification.InterfaceStability.Unstable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.ipc.CallerContext;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.security.token.delegation.DelegationKey;
import org.apache.hadoop.service.AbstractService;
import org.apache.hadoop.yarn.api.records.ApplicationAttemptId;
import org.apache.hadoop.yarn.api.records.ApplicationId;
import org.apache.hadoop.yarn.api.records.ApplicationSubmissionContext;
import org.apache.hadoop.yarn.api.records.ReservationId;
import org.apache.hadoop.yarn.api.records.impl.pb.ApplicationSubmissionContextPBImpl;
import org.apache.hadoop.yarn.conf.HAUtil;
import org.apache.hadoop.yarn.conf.YarnConfiguration;
import org.apache.hadoop.yarn.event.AsyncDispatcher;
import org.apache.hadoop.yarn.event.Dispatcher;
import org.apache.hadoop.yarn.event.EventHandler;
import org.apache.hadoop.yarn.proto.YarnProtos.ReservationAllocationStateProto;
import org.apache.hadoop.yarn.security.client.RMDelegationTokenIdentifier;
import org.apache.hadoop.yarn.server.records.Version;
import org.apache.hadoop.yarn.server.resourcemanager.RMFatalEvent;
import org.apache.hadoop.yarn.server.resourcemanager.RMFatalEventType;
import org.apache.hadoop.yarn.server.resourcemanager.ResourceManager;
import org.apache.hadoop.yarn.server.resourcemanager.recovery.records.AMRMTokenSecretManagerState;
import org.apache.hadoop.yarn.server.resourcemanager.recovery.records.ApplicationAttemptStateData;
import org.apache.hadoop.yarn.server.resourcemanager.recovery.records.ApplicationStateData;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMApp;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMAppEvent;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMAppEventType;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.AggregateAppResourceUsage;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttempt;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptEvent;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptEventType;
import org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptMetrics;
import org.apache.hadoop.yarn.state.InvalidStateTransitionException;
import org.apache.hadoop.yarn.state.MultipleArcTransition;
import org.apache.hadoop.yarn.state.StateMachine;
import org.apache.hadoop.yarn.state.StateMachineFactory;

@Private
@Unstable
/**
 * Base class to implement storage of ResourceManager state.
 * Takes care of asynchronous notifications and interfacing with YARN objects.
 * Real store implementations need to derive from it and implement blocking
 * store and load methods to actually store and load the state.
 */
public abstract class RMStateStore extends AbstractService {

    // constants for RM App state and RMDTSecretManagerState.
    protected static final String RM_APP_ROOT = "RMAppRoot";
    protected static final String RM_DT_SECRET_MANAGER_ROOT = "RMDTSecretManagerRoot";
    protected static final String DELEGATION_KEY_PREFIX = "DelegationKey_";
    protected static final String DELEGATION_TOKEN_PREFIX = "RMDelegationToken_";
    protected static final String DELEGATION_TOKEN_SEQUENCE_NUMBER_PREFIX = "RMDTSequenceNumber_";
    protected static final String AMRMTOKEN_SECRET_MANAGER_ROOT = "AMRMTokenSecretManagerRoot";
    protected static final String RESERVATION_SYSTEM_ROOT = "ReservationSystemRoot";
    protected static final String VERSION_NODE = "RMVersionNode";
    protected static final String EPOCH_NODE = "EpochNode";
    protected ResourceManager resourceManager;
    private final ReadLock readLock;
    private final WriteLock writeLock;

    public static final Log LOG = LogFactory.getLog(RMStateStore.class);

    /**
     * The enum defines state of RMStateStore.
     */
    public enum RMStateStoreState {
        ACTIVE, FENCED
    };

    private static final StateMachineFactory<RMStateStore, RMStateStoreState, RMStateStoreEventType, RMStateStoreEvent> stateMachineFactory = new StateMachineFactory<RMStateStore, RMStateStoreState, RMStateStoreEventType, RMStateStoreEvent>(
            RMStateStoreState.ACTIVE)
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.STORE_APP, new StoreAppTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.UPDATE_APP, new UpdateAppTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.REMOVE_APP, new RemoveAppTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.STORE_APP_ATTEMPT, new StoreAppAttemptTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.UPDATE_APP_ATTEMPT, new UpdateAppAttemptTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.STORE_MASTERKEY, new StoreRMDTMasterKeyTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.REMOVE_MASTERKEY, new RemoveRMDTMasterKeyTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.STORE_DELEGATION_TOKEN, new StoreRMDTTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.REMOVE_DELEGATION_TOKEN, new RemoveRMDTTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.UPDATE_DELEGATION_TOKEN, new UpdateRMDTTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.UPDATE_AMRM_TOKEN, new StoreOrUpdateAMRMTokenTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.STORE_RESERVATION, new StoreReservationAllocationTransition())
                    .addTransition(RMStateStoreState.ACTIVE,
                            EnumSet.of(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED),
                            RMStateStoreEventType.REMOVE_RESERVATION, new RemoveReservationAllocationTransition())
                    .addTransition(RMStateStoreState.ACTIVE, RMStateStoreState.FENCED, RMStateStoreEventType.FENCED)
                    .addTransition(RMStateStoreState.FENCED, RMStateStoreState.FENCED, EnumSet.of(
                            RMStateStoreEventType.STORE_APP, RMStateStoreEventType.UPDATE_APP,
                            RMStateStoreEventType.REMOVE_APP, RMStateStoreEventType.STORE_APP_ATTEMPT,
                            RMStateStoreEventType.UPDATE_APP_ATTEMPT, RMStateStoreEventType.FENCED,
                            RMStateStoreEventType.STORE_MASTERKEY, RMStateStoreEventType.REMOVE_MASTERKEY,
                            RMStateStoreEventType.STORE_DELEGATION_TOKEN,
                            RMStateStoreEventType.REMOVE_DELEGATION_TOKEN,
                            RMStateStoreEventType.UPDATE_DELEGATION_TOKEN, RMStateStoreEventType.UPDATE_AMRM_TOKEN,
                            RMStateStoreEventType.STORE_RESERVATION, RMStateStoreEventType.REMOVE_RESERVATION));

    private final StateMachine<RMStateStoreState, RMStateStoreEventType, RMStateStoreEvent> stateMachine;

    private static class StoreAppTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreAppEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            ApplicationStateData appState = ((RMStateStoreAppEvent) event).getAppState();
            ApplicationId appId = appState.getApplicationSubmissionContext().getApplicationId();
            LOG.info("Storing info for app: " + appId);
            try {
                store.storeApplicationStateInternal(appId, appState);
                store.notifyApplication(new RMAppEvent(appId, RMAppEventType.APP_NEW_SAVED));
            } catch (Exception e) {
                LOG.error("Error storing app: " + appId, e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        };
    }

    private static class UpdateAppTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateUpdateAppEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            ApplicationStateData appState = ((RMStateUpdateAppEvent) event).getAppState();
            ApplicationId appId = appState.getApplicationSubmissionContext().getApplicationId();
            LOG.info("Updating info for app: " + appId);
            try {
                store.updateApplicationStateInternal(appId, appState);
                if (((RMStateUpdateAppEvent) event).isNotifyApplication()) {
                    store.notifyApplication(new RMAppEvent(appId, RMAppEventType.APP_UPDATE_SAVED));
                }
            } catch (Exception e) {
                LOG.error("Error updating app: " + appId, e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        };
    }

    private static class RemoveAppTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreRemoveAppEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            ApplicationStateData appState = ((RMStateStoreRemoveAppEvent) event).getAppState();
            ApplicationId appId = appState.getApplicationSubmissionContext().getApplicationId();
            LOG.info("Removing info for app: " + appId);
            try {
                store.removeApplicationStateInternal(appState);
            } catch (Exception e) {
                LOG.error("Error removing app: " + appId, e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        };
    }

    private static class StoreAppAttemptTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreAppAttemptEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            ApplicationAttemptStateData attemptState = ((RMStateStoreAppAttemptEvent) event).getAppAttemptState();
            try {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Storing info for attempt: " + attemptState.getAttemptId());
                }
                store.storeApplicationAttemptStateInternal(attemptState.getAttemptId(), attemptState);
                store.notifyApplicationAttempt(new RMAppAttemptEvent(attemptState.getAttemptId(),
                        RMAppAttemptEventType.ATTEMPT_NEW_SAVED));
            } catch (Exception e) {
                LOG.error("Error storing appAttempt: " + attemptState.getAttemptId(), e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        };
    }

    private static class UpdateAppAttemptTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateUpdateAppAttemptEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            ApplicationAttemptStateData attemptState = ((RMStateUpdateAppAttemptEvent) event).getAppAttemptState();
            try {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Updating info for attempt: " + attemptState.getAttemptId());
                }
                store.updateApplicationAttemptStateInternal(attemptState.getAttemptId(), attemptState);
                store.notifyApplicationAttempt(new RMAppAttemptEvent(attemptState.getAttemptId(),
                        RMAppAttemptEventType.ATTEMPT_UPDATE_SAVED));
            } catch (Exception e) {
                LOG.error("Error updating appAttempt: " + attemptState.getAttemptId(), e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        };
    }

    private static class StoreRMDTTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreRMDTEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreRMDTEvent dtEvent = (RMStateStoreRMDTEvent) event;
            try {
                LOG.info("Storing RMDelegationToken and SequenceNumber");
                store.storeRMDelegationTokenState(dtEvent.getRmDTIdentifier(), dtEvent.getRenewDate());
            } catch (Exception e) {
                LOG.error("Error While Storing RMDelegationToken and SequenceNumber ", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class RemoveRMDTTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreRMDTEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreRMDTEvent dtEvent = (RMStateStoreRMDTEvent) event;
            try {
                LOG.info("Removing RMDelegationToken and SequenceNumber");
                store.removeRMDelegationTokenState(dtEvent.getRmDTIdentifier());
            } catch (Exception e) {
                LOG.error("Error While Removing RMDelegationToken and SequenceNumber ", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class UpdateRMDTTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreRMDTEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreRMDTEvent dtEvent = (RMStateStoreRMDTEvent) event;
            try {
                LOG.info("Updating RMDelegationToken and SequenceNumber");
                store.updateRMDelegationTokenState(dtEvent.getRmDTIdentifier(), dtEvent.getRenewDate());
            } catch (Exception e) {
                LOG.error("Error While Updating RMDelegationToken and SequenceNumber ", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class StoreRMDTMasterKeyTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreRMDTMasterKeyEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreRMDTMasterKeyEvent dtEvent = (RMStateStoreRMDTMasterKeyEvent) event;
            try {
                LOG.info("Storing RMDTMasterKey.");
                store.storeRMDTMasterKeyState(dtEvent.getDelegationKey());
            } catch (Exception e) {
                LOG.error("Error While Storing RMDTMasterKey.", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class RemoveRMDTMasterKeyTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreRMDTMasterKeyEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreRMDTMasterKeyEvent dtEvent = (RMStateStoreRMDTMasterKeyEvent) event;
            try {
                LOG.info("Removing RMDTMasterKey.");
                store.removeRMDTMasterKeyState(dtEvent.getDelegationKey());
            } catch (Exception e) {
                LOG.error("Error While Removing RMDTMasterKey.", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class StoreOrUpdateAMRMTokenTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreAMRMTokenEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            RMStateStoreAMRMTokenEvent amrmEvent = (RMStateStoreAMRMTokenEvent) event;
            boolean isFenced = false;
            try {
                LOG.info("Updating AMRMToken");
                store.storeOrUpdateAMRMTokenSecretManagerState(amrmEvent.getAmrmTokenSecretManagerState(),
                        amrmEvent.isUpdate());
            } catch (Exception e) {
                LOG.error("Error storing info for AMRMTokenSecretManager", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class StoreReservationAllocationTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreStoreReservationEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreStoreReservationEvent reservationEvent = (RMStateStoreStoreReservationEvent) event;
            try {
                LOG.info("Storing reservation allocation." + reservationEvent.getReservationIdName());
                store.storeReservationState(reservationEvent.getReservationAllocation(),
                        reservationEvent.getPlanName(), reservationEvent.getReservationIdName());
            } catch (Exception e) {
                LOG.error("Error while storing reservation allocation.", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static class RemoveReservationAllocationTransition
            implements MultipleArcTransition<RMStateStore, RMStateStoreEvent, RMStateStoreState> {
        @Override
        public RMStateStoreState transition(RMStateStore store, RMStateStoreEvent event) {
            if (!(event instanceof RMStateStoreStoreReservationEvent)) {
                // should never happen
                LOG.error("Illegal event type: " + event.getClass());
                return RMStateStoreState.ACTIVE;
            }
            boolean isFenced = false;
            RMStateStoreStoreReservationEvent reservationEvent = (RMStateStoreStoreReservationEvent) event;
            try {
                LOG.info("Removing reservation allocation." + reservationEvent.getReservationIdName());
                store.removeReservationState(reservationEvent.getPlanName(),
                        reservationEvent.getReservationIdName());
            } catch (Exception e) {
                LOG.error("Error while removing reservation allocation.", e);
                isFenced = store.notifyStoreOperationFailedInternal(e);
            }
            return finalState(isFenced);
        }
    }

    private static RMStateStoreState finalState(boolean isFenced) {
        return isFenced ? RMStateStoreState.FENCED : RMStateStoreState.ACTIVE;
    }

    public RMStateStore() {
        super(RMStateStore.class.getName());
        ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
        this.readLock = lock.readLock();
        this.writeLock = lock.writeLock();
        stateMachine = stateMachineFactory.make(this);
    }

    public static class RMDTSecretManagerState {
        // DTIdentifier -> renewDate
        Map<RMDelegationTokenIdentifier, Long> delegationTokenState = new HashMap<RMDelegationTokenIdentifier, Long>();

        Set<DelegationKey> masterKeyState = new HashSet<DelegationKey>();

        int dtSequenceNumber = 0;

        public Map<RMDelegationTokenIdentifier, Long> getTokenState() {
            return delegationTokenState;
        }

        public Set<DelegationKey> getMasterKeyState() {
            return masterKeyState;
        }

        public int getDTSequenceNumber() {
            return dtSequenceNumber;
        }
    }

    /**
     * State of the ResourceManager
     */
    public static class RMState {
        Map<ApplicationId, ApplicationStateData> appState = new TreeMap<ApplicationId, ApplicationStateData>();

        RMDTSecretManagerState rmSecretManagerState = new RMDTSecretManagerState();

        AMRMTokenSecretManagerState amrmTokenSecretManagerState = null;

        private Map<String, Map<ReservationId, ReservationAllocationStateProto>> reservationState = new TreeMap<>();

        public Map<ApplicationId, ApplicationStateData> getApplicationState() {
            return appState;
        }

        public RMDTSecretManagerState getRMDTSecretManagerState() {
            return rmSecretManagerState;
        }

        public AMRMTokenSecretManagerState getAMRMTokenSecretManagerState() {
            return amrmTokenSecretManagerState;
        }

        public Map<String, Map<ReservationId, ReservationAllocationStateProto>> getReservationState() {
            return reservationState;
        }
    }

    private Dispatcher rmDispatcher;

    /**
     * Dispatcher used to send state operation completion events to 
     * ResourceManager services
     */
    public void setRMDispatcher(Dispatcher dispatcher) {
        this.rmDispatcher = dispatcher;
    }

    AsyncDispatcher dispatcher;

    @Override
    protected void serviceInit(Configuration conf) throws Exception {
        // create async handler
        dispatcher = new AsyncDispatcher();
        dispatcher.init(conf);
        dispatcher.register(RMStateStoreEventType.class, new ForwardingEventHandler());
        dispatcher.setDrainEventsOnStop();
        initInternal(conf);
    }

    @Override
    protected void serviceStart() throws Exception {
        dispatcher.start();
        startInternal();
    }

    /**
     * Derived classes initialize themselves using this method.
     */
    protected abstract void initInternal(Configuration conf) throws Exception;

    /**
     * Derived classes start themselves using this method.
     * The base class is started and the event dispatcher is ready to use at
     * this point
     */
    protected abstract void startInternal() throws Exception;

    @Override
    protected void serviceStop() throws Exception {
        dispatcher.stop();
        closeInternal();
    }

    /**
     * Derived classes close themselves using this method.
     * The base class will be closed and the event dispatcher will be shutdown 
     * after this
     */
    protected abstract void closeInternal() throws Exception;

    /**
     * 1) Versioning scheme: major.minor. For e.g. 1.0, 1.1, 1.2...1.25, 2.0 etc.
     * 2) Any incompatible change of state-store is a major upgrade, and any
     *    compatible change of state-store is a minor upgrade.
     * 3) If theres's no version, treat it as CURRENT_VERSION_INFO.
     * 4) Within a minor upgrade, say 1.1 to 1.2:
     *    overwrite the version info and proceed as normal.
     * 5) Within a major upgrade, say 1.2 to 2.0:
     *    throw exception and indicate user to use a separate upgrade tool to
     *    upgrade RM state.
     */
    public void checkVersion() throws Exception {
        Version loadedVersion = loadVersion();
        LOG.info("Loaded RM state version info " + loadedVersion);
        if (loadedVersion != null && loadedVersion.equals(getCurrentVersion())) {
            return;
        }
        // if there is no version info, treat it as CURRENT_VERSION_INFO;
        if (loadedVersion == null) {
            loadedVersion = getCurrentVersion();
        }
        if (loadedVersion.isCompatibleTo(getCurrentVersion())) {
            LOG.info("Storing RM state version info " + getCurrentVersion());
            storeVersion();
        } else {
            throw new RMStateVersionIncompatibleException(
                    "Expecting RM state version " + getCurrentVersion() + ", but loading version " + loadedVersion);
        }
    }

    /**
     * Derived class use this method to load the version information from state
     * store.
     */
    protected abstract Version loadVersion() throws Exception;

    /**
     * Derived class use this method to store the version information.
     */
    protected abstract void storeVersion() throws Exception;

    /**
     * Get the current version of the underlying state store.
     */
    protected abstract Version getCurrentVersion();

    /**
     * Get the current epoch of RM and increment the value.
     */
    public abstract long getAndIncrementEpoch() throws Exception;

    /**
     * Blocking API
     * The derived class must recover state from the store and return a new 
     * RMState object populated with that state
     * This must not be called on the dispatcher thread
     */
    public abstract RMState loadState() throws Exception;

    /**
     * Non-Blocking API
     * ResourceManager services use this to store the application's state
     * This does not block the dispatcher threads
     * RMAppStoredEvent will be sent on completion to notify the RMApp
     */
    @SuppressWarnings("unchecked")
    public void storeNewApplication(RMApp app) {
        ApplicationSubmissionContext context = app.getApplicationSubmissionContext();
        assert context instanceof ApplicationSubmissionContextPBImpl;
        ApplicationStateData appState = ApplicationStateData.newInstance(app.getSubmitTime(), app.getStartTime(),
                context, app.getUser(), app.getCallerContext());
        dispatcher.getEventHandler().handle(new RMStateStoreAppEvent(appState));
    }

    @SuppressWarnings("unchecked")
    public void updateApplicationState(ApplicationStateData appState) {
        dispatcher.getEventHandler().handle(new RMStateUpdateAppEvent(appState));
    }

    @SuppressWarnings("unchecked")
    public void updateApplicationStateNoNotify(ApplicationStateData appState) {
        dispatcher.getEventHandler().handle(new RMStateUpdateAppEvent(appState, false));
    }

    public void updateApplicationStateSynchronously(ApplicationStateData appState, boolean notifyApp) {
        handleStoreEvent(new RMStateUpdateAppEvent(appState, notifyApp));
    }

    public void updateFencedState() {
        handleStoreEvent(new RMStateStoreEvent(RMStateStoreEventType.FENCED));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to store the state of an 
     * application.
     */
    protected abstract void storeApplicationStateInternal(ApplicationId appId, ApplicationStateData appStateData)
            throws Exception;

    protected abstract void updateApplicationStateInternal(ApplicationId appId, ApplicationStateData appStateData)
            throws Exception;

    @SuppressWarnings("unchecked")
    /**
     * Non-blocking API
     * ResourceManager services call this to store state on an application attempt
     * This does not block the dispatcher threads
     * RMAppAttemptStoredEvent will be sent on completion to notify the RMAppAttempt
     */
    public void storeNewApplicationAttempt(RMAppAttempt appAttempt) {
        Credentials credentials = getCredentialsFromAppAttempt(appAttempt);
        RMAppAttemptMetrics attempMetrics = appAttempt.getRMAppAttemptMetrics();
        AggregateAppResourceUsage resUsage = attempMetrics.getAggregateAppResourceUsage();
        ApplicationAttemptStateData attemptState = ApplicationAttemptStateData.newInstance(
                appAttempt.getAppAttemptId(), appAttempt.getMasterContainer(), credentials,
                appAttempt.getStartTime(), resUsage.getMemorySeconds(), resUsage.getVcoreSeconds(),
                resUsage.getGPUSeconds(), attempMetrics.getPreemptedMemory(), attempMetrics.getPreemptedVcore(),
                attempMetrics.getPreemptedGPU(), appAttempt.getTrackingUrl());

        dispatcher.getEventHandler().handle(new RMStateStoreAppAttemptEvent(attemptState));
    }

    @SuppressWarnings("unchecked")
    public void updateApplicationAttemptState(ApplicationAttemptStateData attemptState) {
        dispatcher.getEventHandler().handle(new RMStateUpdateAppAttemptEvent(attemptState));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to store the state of an 
     * application attempt
     */
    protected abstract void storeApplicationAttemptStateInternal(ApplicationAttemptId attemptId,
            ApplicationAttemptStateData attemptStateData) throws Exception;

    protected abstract void updateApplicationAttemptStateInternal(ApplicationAttemptId attemptId,
            ApplicationAttemptStateData attemptStateData) throws Exception;

    /**
     * RMDTSecretManager call this to store the state of a delegation token
     * and sequence number
     */
    public void storeRMDelegationToken(RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate) {
        handleStoreEvent(
                new RMStateStoreRMDTEvent(rmDTIdentifier, renewDate, RMStateStoreEventType.STORE_DELEGATION_TOKEN));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to store the state of
     * RMDelegationToken and sequence number
     */
    protected abstract void storeRMDelegationTokenState(RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate)
            throws Exception;

    /**
     * RMDTSecretManager call this to remove the state of a delegation token
     */
    public void removeRMDelegationToken(RMDelegationTokenIdentifier rmDTIdentifier) {
        handleStoreEvent(
                new RMStateStoreRMDTEvent(rmDTIdentifier, null, RMStateStoreEventType.REMOVE_DELEGATION_TOKEN));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to remove the state of RMDelegationToken
     */
    protected abstract void removeRMDelegationTokenState(RMDelegationTokenIdentifier rmDTIdentifier)
            throws Exception;

    /**
     * RMDTSecretManager call this to update the state of a delegation token
     * and sequence number
     */
    public void updateRMDelegationToken(RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate) {
        handleStoreEvent(new RMStateStoreRMDTEvent(rmDTIdentifier, renewDate,
                RMStateStoreEventType.UPDATE_DELEGATION_TOKEN));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to update the state of
     * RMDelegationToken and sequence number
     */
    protected abstract void updateRMDelegationTokenState(RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate)
            throws Exception;

    /**
     * RMDTSecretManager call this to store the state of a master key
     */
    public void storeRMDTMasterKey(DelegationKey delegationKey) {
        handleStoreEvent(new RMStateStoreRMDTMasterKeyEvent(delegationKey, RMStateStoreEventType.STORE_MASTERKEY));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to store the state of
     * DelegationToken Master Key
     */
    protected abstract void storeRMDTMasterKeyState(DelegationKey delegationKey) throws Exception;

    /**
     * RMDTSecretManager call this to remove the state of a master key
     */
    public void removeRMDTMasterKey(DelegationKey delegationKey) {
        handleStoreEvent(new RMStateStoreRMDTMasterKeyEvent(delegationKey, RMStateStoreEventType.REMOVE_MASTERKEY));
    }

    /**
     * Blocking Apis to maintain reservation state.
     */
    public void storeNewReservation(ReservationAllocationStateProto reservationAllocation, String planName,
            String reservationIdName) {
        handleStoreEvent(new RMStateStoreStoreReservationEvent(reservationAllocation,
                RMStateStoreEventType.STORE_RESERVATION, planName, reservationIdName));
    }

    public void removeReservation(String planName, String reservationIdName) {
        handleStoreEvent(new RMStateStoreStoreReservationEvent(null, RMStateStoreEventType.REMOVE_RESERVATION,
                planName, reservationIdName));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to store the state of
     * a reservation allocation.
     */
    protected abstract void storeReservationState(ReservationAllocationStateProto reservationAllocation,
            String planName, String reservationIdName) throws Exception;

    /**
     * Blocking API
     * Derived classes must implement this method to remove the state of
     * a reservation allocation.
     */
    protected abstract void removeReservationState(String planName, String reservationIdName) throws Exception;

    /**
     * Blocking API
     * Derived classes must implement this method to remove the state of
     * DelegationToken Master Key
     */
    protected abstract void removeRMDTMasterKeyState(DelegationKey delegationKey) throws Exception;

    /**
     * Blocking API Derived classes must implement this method to store or update
     * the state of AMRMToken Master Key
     */
    protected abstract void storeOrUpdateAMRMTokenSecretManagerState(
            AMRMTokenSecretManagerState amrmTokenSecretManagerState, boolean isUpdate) throws Exception;

    /**
     * Store or Update state of AMRMToken Master Key
     */
    public void storeOrUpdateAMRMTokenSecretManager(AMRMTokenSecretManagerState amrmTokenSecretManagerState,
            boolean isUpdate) {
        handleStoreEvent(new RMStateStoreAMRMTokenEvent(amrmTokenSecretManagerState, isUpdate,
                RMStateStoreEventType.UPDATE_AMRM_TOKEN));
    }

    /**
     * Non-blocking API
     * ResourceManager services call this to remove an application from the state
     * store
     * This does not block the dispatcher threads
     * There is no notification of completion for this operation.
     */
    @SuppressWarnings("unchecked")
    public void removeApplication(RMApp app) {
        ApplicationStateData appState = ApplicationStateData.newInstance(app.getSubmitTime(), app.getStartTime(),
                app.getApplicationSubmissionContext(), app.getUser(), app.getCallerContext());
        for (RMAppAttempt appAttempt : app.getAppAttempts().values()) {
            appState.attempts.put(appAttempt.getAppAttemptId(), null);
        }

        dispatcher.getEventHandler().handle(new RMStateStoreRemoveAppEvent(appState));
    }

    /**
     * Blocking API
     * Derived classes must implement this method to remove the state of an 
     * application and its attempts
     */
    protected abstract void removeApplicationStateInternal(ApplicationStateData appState) throws Exception;

    // TODO: This should eventually become cluster-Id + "AM_RM_TOKEN_SERVICE". See
    // YARN-1779
    public static final Text AM_RM_TOKEN_SERVICE = new Text("AM_RM_TOKEN_SERVICE");

    public static final Text AM_CLIENT_TOKEN_MASTER_KEY_NAME = new Text("YARN_CLIENT_TOKEN_MASTER_KEY");

    public Credentials getCredentialsFromAppAttempt(RMAppAttempt appAttempt) {
        Credentials credentials = new Credentials();

        SecretKey clientTokenMasterKey = appAttempt.getClientTokenMasterKey();
        if (clientTokenMasterKey != null) {
            credentials.addSecretKey(AM_CLIENT_TOKEN_MASTER_KEY_NAME, clientTokenMasterKey.getEncoded());
        }
        return credentials;
    }

    @VisibleForTesting
    protected boolean isFencedState() {
        return (RMStateStoreState.FENCED == getRMStateStoreState());
    }

    // Dispatcher related code
    protected void handleStoreEvent(RMStateStoreEvent event) {
        this.writeLock.lock();
        try {

            if (LOG.isDebugEnabled()) {
                LOG.debug("Processing event of type " + event.getType());
            }

            final RMStateStoreState oldState = getRMStateStoreState();

            this.stateMachine.doTransition(event.getType(), event);

            if (oldState != getRMStateStoreState()) {
                LOG.info("RMStateStore state change from " + oldState + " to " + getRMStateStoreState());
            }

        } catch (InvalidStateTransitionException e) {
            LOG.error("Can't handle this event at current state", e);
        } finally {
            this.writeLock.unlock();
        }
    }

    /**
     * This method is called to notify the ResourceManager that the store
     * operation has failed.
     * @param failureCause the exception due to which the operation failed
     */
    protected void notifyStoreOperationFailed(Exception failureCause) {
        if (isFencedState()) {
            return;
        }
        if (notifyStoreOperationFailedInternal(failureCause)) {
            updateFencedState();
        }
    }

    @SuppressWarnings("unchecked")
    private boolean notifyStoreOperationFailedInternal(Exception failureCause) {
        boolean isFenced = false;
        LOG.error("State store operation failed ", failureCause);
        if (HAUtil.isHAEnabled(getConfig())) {
            LOG.warn("State-store fenced ! Transitioning RM to standby");
            isFenced = true;
            Thread standByTransitionThread = new Thread(new StandByTransitionThread());
            standByTransitionThread.setName("StandByTransitionThread Handler");
            standByTransitionThread.start();
        } else if (YarnConfiguration.shouldRMFailFast(getConfig())) {
            LOG.fatal("Fail RM now due to state-store error!");
            rmDispatcher.getEventHandler()
                    .handle(new RMFatalEvent(RMFatalEventType.STATE_STORE_OP_FAILED, failureCause));
        } else {
            LOG.warn("Skip the state-store error.");
        }
        return isFenced;
    }

    @SuppressWarnings("unchecked")
    /**
     * This method is called to notify the application that
     * new application is stored or updated in state store
     * @param event App event containing the app id and event type
     */
    private void notifyApplication(RMAppEvent event) {
        rmDispatcher.getEventHandler().handle(event);
    }

    @SuppressWarnings("unchecked")
    /**
     * This method is called to notify the application attempt
     * that new attempt is stored or updated in state store
     * @param event App attempt event containing the app attempt
     * id and event type
     */
    private void notifyApplicationAttempt(RMAppAttemptEvent event) {
        rmDispatcher.getEventHandler().handle(event);
    }

    /**
     * EventHandler implementation which forward events to the FSRMStateStore
     * This hides the EventHandle methods of the store from its public interface 
     */
    private final class ForwardingEventHandler implements EventHandler<RMStateStoreEvent> {

        @Override
        public void handle(RMStateStoreEvent event) {
            handleStoreEvent(event);
        }
    }

    /**
     * Derived classes must implement this method to delete the state store
     * @throws Exception
     */
    public abstract void deleteStore() throws Exception;

    /**
     * Derived classes must implement this method to remove application from the
     * state store
     * 
     * @throws Exception
     */
    public abstract void removeApplication(ApplicationId removeAppId) throws Exception;

    public void setResourceManager(ResourceManager rm) {
        this.resourceManager = rm;
    }

    private class StandByTransitionThread implements Runnable {
        @Override
        public void run() {
            LOG.info("RMStateStore has been fenced");
            resourceManager.handleTransitionToStandBy();
        }
    }

    public RMStateStoreState getRMStateStoreState() {
        this.readLock.lock();
        try {
            return this.stateMachine.getCurrentState();
        } finally {
            this.readLock.unlock();
        }
    }
}