org.neo4j.kernel.ha.cluster.SwitchToSlave Maven / Gradle / Ivy
/*
* Copyright (c) 2002-2016 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see neoDataSourceSupplier;
private final Supplier transactionIdStoreSupplier;
private final Function slaveServerFactory;
private final UpdatePuller updatePuller;
private final PageCache pageCache;
private final Monitors monitors;
private final TransactionStats transactionCounters;
private final Log userLog;
private final Log msgLog;
private final Config config;
private final DependencyResolver resolver;
private final HaIdGeneratorFactory idGeneratorFactory;
private final DelegateInvocationHandler masterDelegateHandler;
private final ClusterMemberAvailability clusterMemberAvailability;
private final RequestContextFactory requestContextFactory;
private final MasterClientResolver masterClientResolver;
private final StoreCopyClient storeCopyClient;
private final PullerFactory updatePullerFactory;
private final Monitor monitor;
public SwitchToSlave( File storeDir,
LogService logService,
FileSystemAbstraction fileSystemAbstraction,
Config config,
DependencyResolver resolver,
HaIdGeneratorFactory idGeneratorFactory,
DelegateInvocationHandler masterDelegateHandler,
ClusterMemberAvailability clusterMemberAvailability,
RequestContextFactory requestContextFactory,
PullerFactory pullerFactory,
Iterable> kernelExtensions,
MasterClientResolver masterClientResolver,
Monitor monitor,
StoreCopyClient.Monitor storeCopyMonitor,
Supplier neoDataSourceSupplier,
Supplier transactionIdStoreSupplier,
Function slaveServerFactory,
UpdatePuller updatePuller,
PageCache pageCache,
Monitors monitors,
TransactionStats transactionCounters )
{
this( storeDir,
logService,
config,
resolver,
idGeneratorFactory,
masterDelegateHandler,
clusterMemberAvailability,
requestContextFactory,
pullerFactory,
masterClientResolver,
monitor,
new StoreCopyClient( storeDir, config, kernelExtensions, logService.getUserLogProvider(),
fileSystemAbstraction, pageCache, storeCopyMonitor, false ),
neoDataSourceSupplier,
transactionIdStoreSupplier,
slaveServerFactory,
updatePuller,
pageCache,
monitors,
transactionCounters );
}
SwitchToSlave( File storeDir,
LogService logService,
Config config,
DependencyResolver resolver,
HaIdGeneratorFactory idGeneratorFactory,
DelegateInvocationHandler masterDelegateHandler,
ClusterMemberAvailability clusterMemberAvailability,
RequestContextFactory requestContextFactory,
PullerFactory pullerFactory,
MasterClientResolver masterClientResolver,
Monitor monitor,
StoreCopyClient storeCopyClient,
Supplier neoDataSourceSupplier,
Supplier transactionIdStoreSupplier,
Function slaveServerFactory,
UpdatePuller updatePuller,
PageCache pageCache,
Monitors monitors,
TransactionStats transactionCounters )
{
this.neoDataSourceSupplier = neoDataSourceSupplier;
this.transactionIdStoreSupplier = transactionIdStoreSupplier;
this.slaveServerFactory = slaveServerFactory;
this.updatePuller = updatePuller;
this.pageCache = pageCache;
this.monitors = monitors;
this.transactionCounters = transactionCounters;
this.userLog = logService.getUserLog( getClass() );
this.storeDir = storeDir;
this.config = config;
this.resolver = resolver;
this.idGeneratorFactory = idGeneratorFactory;
this.clusterMemberAvailability = clusterMemberAvailability;
this.requestContextFactory = requestContextFactory;
this.msgLog = logService.getInternalLog( getClass() );
this.masterDelegateHandler = masterDelegateHandler;
this.updatePullerFactory = pullerFactory;
this.monitor = monitor;
this.masterClientResolver = masterClientResolver;
this.storeCopyClient = storeCopyClient;
}
/**
* Performs a switch to the slave state. Starts the communication endpoints, switches components to the slave state
* and ensures that the current database is appropriate for this cluster. It also broadcasts the appropriate
* Slave Is Available event
*
* @param haCommunicationLife The LifeSupport instance to register the network facilities required for
* communication with the rest of the cluster
* @param me The URI this instance must bind to
* @param masterUri The URI of the master for which this instance must become slave to
* @param cancellationRequest A handle for gracefully aborting the switch
* @return The URI that was broadcasted as the slave endpoint or null if the task was cancelled
* @throws Throwable
*/
public URI switchToSlave( LifeSupport haCommunicationLife, URI me, URI masterUri,
CancellationRequest cancellationRequest ) throws Throwable
{
URI slaveUri;
boolean success = false;
monitor.switchToSlaveStarted();
// Wait a short while for current transactions to stop first, just to be nice.
// We can't wait forever since switching to our designated role is quite important.
Clock clock = Clocks.systemClock();
long deadline = clock.millis() + config.get( HaSettings.internal_state_switch_timeout );
while ( transactionCounters.getNumberOfActiveTransactions() > 0 && clock.millis() < deadline )
{
parkNanos( MILLISECONDS.toNanos( 10 ) );
}
try
{
InstanceId myId = config.get( ClusterSettings.server_id );
userLog.info( "ServerId %s, moving to slave for master %s", myId, masterUri );
assert masterUri != null; // since we are here it must already have been set from outside
idGeneratorFactory.switchToSlave();
copyStoreFromMasterIfNeeded( masterUri, me, cancellationRequest );
/*
* The following check is mandatory, since the store copy can be cancelled and if it was actually
* happening then we can't continue, as there is no store in place
*/
if ( cancellationRequest.cancellationRequested() )
{
msgLog.info( "Switch to slave cancelled during store copy if no local store is present." );
return null;
}
/*
* We get here either with a fresh store from the master copy above so we need to
* start the ds or we already had a store, so we have already started the ds. Either way,
* make sure it's there.
*/
NeoStoreDataSource neoDataSource = neoDataSourceSupplier.get();
neoDataSource.afterModeSwitch();
StoreId myStoreId = neoDataSource.getStoreId();
boolean consistencyChecksExecutedSuccessfully = executeConsistencyChecks(
transactionIdStoreSupplier.get(), masterUri, me, myStoreId, cancellationRequest );
if ( !consistencyChecksExecutedSuccessfully )
{
msgLog.info( "Switch to slave cancelled due to consistency check failure." );
return null;
}
if ( cancellationRequest.cancellationRequested() )
{
msgLog.info( "Switch to slave cancelled after consistency checks." );
return null;
}
// no exception were thrown and we can proceed
slaveUri = startHaCommunication( haCommunicationLife, neoDataSource, me, masterUri, myStoreId, cancellationRequest );
if ( slaveUri == null )
{
msgLog.info( "Switch to slave unable to connect." );
return null;
}
success = true;
userLog.info( "ServerId %s, successfully moved to slave for master %s", myId, masterUri );
}
finally
{
monitor.switchToSlaveCompleted( success );
}
return slaveUri;
}
private void copyStoreFromMasterIfNeeded( URI masterUri, URI me, CancellationRequest cancellationRequest )
throws Throwable
{
if ( !isStorePresent( pageCache, storeDir ) )
{
boolean success = false;
monitor.storeCopyStarted();
LifeSupport copyLife = new LifeSupport();
try
{
MasterClient masterClient = newMasterClient( masterUri, me, null, copyLife );
copyLife.start();
boolean masterIsOld = MasterClient.CURRENT.compareTo( masterClient.getProtocolVersion() ) > 0;
if ( masterIsOld )
{
throw new UnableToCopyStoreFromOldMasterException( MasterClient.CURRENT.getApplicationProtocol(),
masterClient.getProtocolVersion().getApplicationProtocol() );
}
else
{
copyStoreFromMaster( masterClient, cancellationRequest );
success = true;
}
}
finally
{
monitor.storeCopyCompleted( success );
copyLife.shutdown();
}
}
}
private boolean executeConsistencyChecks( TransactionIdStore txIdStore,
URI masterUri, URI me,
StoreId storeId,
CancellationRequest cancellationRequest ) throws Throwable
{
LifeSupport consistencyCheckLife = new LifeSupport();
try
{
MasterClient masterClient = newMasterClient( masterUri, me, storeId, consistencyCheckLife );
consistencyCheckLife.start();
if ( cancellationRequest.cancellationRequested() )
{
return false;
}
checkDataConsistency( masterClient, txIdStore, storeId, masterUri );
}
finally
{
consistencyCheckLife.shutdown();
}
return true;
}
void checkDataConsistency( MasterClient masterClient, TransactionIdStore txIdStore, StoreId storeId, URI masterUri )
throws Throwable
{
try
{
userLog.info( "Checking store consistency with master" );
checkMyStoreIdAndMastersStoreId( storeId, masterUri );
checkDataConsistencyWithMaster( masterUri, masterClient, storeId, txIdStore );
userLog.info( "Store is consistent" );
}
catch ( StoreUnableToParticipateInClusterException upe )
{
userLog.info( "The store is inconsistent. Will treat it as branched and fetch a new one from the master" );
msgLog.warn( "Current store is unable to participate in the cluster; fetching new store from master", upe );
try
{
stopServicesAndHandleBranchedStore( config.get( HaSettings.branched_data_policy ) );
}
catch ( IOException e )
{
msgLog.warn( "Failed while trying to handle branched data", e );
}
throw upe;
}
catch ( MismatchingStoreIdException e )
{
userLog.info(
"The store does not represent the same database as master. Will remove and fetch a new one from " +
"master" );
if ( txIdStore.getLastCommittedTransactionId() == BASE_TX_ID )
{
msgLog.warn( "Found and deleting empty store with mismatching store id", e );
stopServicesAndHandleBranchedStore( BranchedDataPolicy.keep_none );
throw e;
}
msgLog.error( "Store cannot participate in cluster due to mismatching store IDs", e );
throw new ForeignStoreException( e.getExpected(), e.getEncountered() );
}
}
private void checkMyStoreIdAndMastersStoreId( StoreId myStoreId, URI masterUri )
{
ClusterMembers clusterMembers = resolver.resolveDependency( ClusterMembers.class );
InstanceId serverId = HighAvailabilityModeSwitcher.getServerId( masterUri );
Iterable members = clusterMembers.getMembers();
ClusterMember master = firstOrNull( filter( hasInstanceId( serverId ), members ) );
if ( master == null )
{
throw new IllegalStateException( "Cannot find the master among " + members +
" with master serverId=" + serverId + " and uri=" + masterUri );
}
StoreId masterStoreId = master.getStoreId();
if ( !myStoreId.equals( masterStoreId ) )
{
throw new MismatchingStoreIdException( myStoreId, master.getStoreId() );
}
else if ( !myStoreId.equalsByUpgradeId( master.getStoreId() ) )
{
throw new BranchedDataException( "My store with " + myStoreId + " was updated independently from " +
"master's store " + masterStoreId );
}
}
private URI startHaCommunication( LifeSupport haCommunicationLife, NeoStoreDataSource neoDataSource,
URI me, URI masterUri, StoreId storeId, CancellationRequest cancellationRequest )
throws IllegalArgumentException, InterruptedException
{
MasterClient master = newMasterClient( masterUri, me, neoDataSource.getStoreId(), haCommunicationLife );
TransactionObligationFulfiller obligationFulfiller =
resolver.resolveDependency( TransactionObligationFulfiller.class );
UpdatePullerScheduler updatePullerScheduler = updatePullerFactory.createUpdatePullerScheduler( updatePuller );
Slave slaveImpl = new SlaveImpl( obligationFulfiller );
SlaveServer server = slaveServerFactory.apply( slaveImpl );
if ( cancellationRequest.cancellationRequested() )
{
msgLog.info( "Switch to slave cancelled, unable to start HA-communication" );
return null;
}
masterDelegateHandler.setDelegate( master );
haCommunicationLife.add( updatePullerScheduler );
haCommunicationLife.add( server );
haCommunicationLife.start();
/*
* Take the opportunity to catch up with master, now that we're alone here, right before we
* drop the availability guard, so that other transactions might start.
*/
if ( !catchUpWithMaster( updatePuller ) )
{
return null;
}
URI slaveHaURI = createHaURI( me, server );
clusterMemberAvailability.memberIsAvailable( HighAvailabilityModeSwitcher.SLAVE, slaveHaURI, storeId );
return slaveHaURI;
}
private boolean catchUpWithMaster( UpdatePuller updatePuller ) throws IllegalArgumentException, InterruptedException
{
monitor.catchupStarted();
RequestContext catchUpRequestContext = requestContextFactory.newRequestContext();
userLog.info( "Catching up with master. I'm at %s", catchUpRequestContext );
if ( !updatePuller.tryPullUpdates() )
{
return false;
}
userLog.info( "Now caught up with master" );
monitor.catchupCompleted();
return true;
}
private URI createHaURI( URI me, Server server )
{
String hostString = ServerUtil.getHostString( server.getSocketAddress() );
int port = server.getSocketAddress().getPort();
InstanceId serverId = config.get( ClusterSettings.server_id );
String host = hostString.contains( HighAvailabilityModeSwitcher.INADDR_ANY ) ? me.getHost() : hostString;
return URI.create( "ha://" + host + ":" + port + "?serverId=" + serverId );
}
private void copyStoreFromMaster( final MasterClient masterClient,
CancellationRequest cancellationRequest ) throws Throwable
{
try
{
// This will move the copied db to the graphdb location
userLog.info( "Copying store from master" );
storeCopyClient.copyStore(
new StoreCopyClient.StoreCopyRequester()
{
@Override
public Response copyStore( StoreWriter writer )
{
return masterClient.copyStore( new RequestContext( 0,
config.get( ClusterSettings.server_id ).toIntegerIndex(), 0, BASE_TX_ID, 0 ), writer );
}
@Override
public void done()
{ // Nothing to clean up here
}
}, cancellationRequest );
startServicesAgain();
userLog.info( "Finished copying store from master" );
}
catch ( Throwable t )
{
// Delete store so that we can copy from master without conflicts next time
cleanStoreDir();
throw t;
}
}
void cleanStoreDir() throws IOException
{
// Tests verify that this method is called
StoreUtil.cleanStoreDir( storeDir );
}
private MasterClient newMasterClient( URI masterUri, URI me, StoreId storeId, LifeSupport life )
{
MasterClient masterClient = masterClientResolver.instantiate( masterUri.getHost(), masterUri.getPort(),
me.getHost(), monitors, storeId, life );
if ( masterClient.getProtocolVersion().compareTo( MasterClient210.PROTOCOL_VERSION ) < 0 )
{
idGeneratorFactory.enableCompatibilityMode();
}
return masterClient;
}
private void startServicesAgain() throws Throwable
{
msgLog.debug( "Starting services again" );
for ( Class serviceClass : SERVICES_TO_RESTART_FOR_STORE_COPY )
{
resolver.resolveDependency( serviceClass ).start();
}
}
void stopServicesAndHandleBranchedStore( BranchedDataPolicy branchPolicy ) throws Throwable
{
msgLog.debug( "Stopping services to handle branched store" );
for ( int i = SERVICES_TO_RESTART_FOR_STORE_COPY.length - 1; i >= 0; i-- )
{
Class serviceClass = SERVICES_TO_RESTART_FOR_STORE_COPY[i];
resolver.resolveDependency( serviceClass ).stop();
}
branchPolicy.handle( storeDir );
}
private void checkDataConsistencyWithMaster( URI availableMasterId, Master master,
StoreId storeId,
TransactionIdStore transactionIdStore )
{
TransactionId myLastCommittedTxData = transactionIdStore.getLastCommittedTransaction();
long myLastCommittedTx = myLastCommittedTxData.transactionId();
HandshakeResult handshake;
try ( Response response = master.handshake( myLastCommittedTx, storeId ) )
{
handshake = response.response();
requestContextFactory.setEpoch( handshake.epoch() );
}
catch ( BranchedDataException e )
{
// Rethrow wrapped in a branched data exception on our side, to clarify where the problem originates.
throw new BranchedDataException( "The database stored on this machine has diverged from that " +
"of the master. This will be automatically resolved.", e );
}
catch ( RuntimeException e )
{
// Checked exceptions will be wrapped as the cause if this was a serialized
// server-side exception
if ( e.getCause() instanceof MissingLogDataException )
{
/*
* This means the master was unable to find a log entry for the txid we just asked. This
* probably means the thing we asked for is too old or too new. Anyway, since it doesn't
* have the tx it is better if we just throw our store away and ask for a new copy. Next
* time around it shouldn't have to even pass from here.
*/
throw new StoreOutOfDateException( "The master is missing the log required to complete the " +
"consistency check", e.getCause() );
}
throw e;
}
long myChecksum = myLastCommittedTxData.checksum();
if ( myChecksum != handshake.txChecksum() )
{
String msg = "The cluster contains two logically different versions of the database.. This will be " +
"automatically resolved. Details: I (server_id:" + config.get( ClusterSettings.server_id ) +
") think checksum for txId (" + myLastCommittedTx + ") is " + myChecksum +
", but master (server_id:" + getServerId( availableMasterId ) + ") says that it's " +
handshake.txChecksum() + ", where handshake is " + handshake;
throw new BranchedDataException( msg );
}
msgLog.info( "Checksum for last committed tx ok with lastTxId=" +
myLastCommittedTx + " with checksum=" + myChecksum, true );
}
}
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