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ReadReplicaStartupProcess.java
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ReadReplicaStartupProcess.java
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/*
* Copyright (c) 2002-2017 "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 <http://www.gnu.org/licenses/>.
*/
package org.neo4j.causalclustering.readreplica;
import java.io.IOException;
import java.util.concurrent.locks.LockSupport;
import org.neo4j.causalclustering.catchup.storecopy.CopiedStoreRecovery;
import org.neo4j.causalclustering.catchup.storecopy.LocalDatabase;
import org.neo4j.causalclustering.catchup.storecopy.StoreCopyFailedException;
import org.neo4j.causalclustering.catchup.storecopy.StoreFetcher;
import org.neo4j.causalclustering.catchup.storecopy.StoreIdDownloadFailedException;
import org.neo4j.causalclustering.catchup.storecopy.StreamingTransactionsFailedException;
import org.neo4j.causalclustering.core.state.machines.tx.RetryStrategy;
import org.neo4j.causalclustering.identity.MemberId;
import org.neo4j.causalclustering.identity.StoreId;
import org.neo4j.causalclustering.messaging.routing.CoreMemberSelectionException;
import org.neo4j.causalclustering.messaging.routing.CoreMemberSelectionStrategy;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.kernel.lifecycle.Lifecycle;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;
import static java.lang.String.format;
class ReadReplicaStartupProcess implements Lifecycle
{
private static final int MAX_ATTEMPTS = 5;
private final FileSystemAbstraction fs;
private final StoreFetcher storeFetcher;
private final LocalDatabase localDatabase;
private final Lifecycle txPulling;
private final CoreMemberSelectionStrategy connectionStrategy;
private final Log debugLog;
private final Log userLog;
private final RetryStrategy retryStrategy;
private final CopiedStoreRecovery copiedStoreRecovery;
private String lastIssue;
ReadReplicaStartupProcess( FileSystemAbstraction fs, StoreFetcher storeFetcher, LocalDatabase localDatabase,
Lifecycle txPulling, CoreMemberSelectionStrategy connectionStrategy, RetryStrategy retryStrategy,
LogProvider debugLogProvider, LogProvider userLogProvider, CopiedStoreRecovery copiedStoreRecovery )
{
this.fs = fs;
this.storeFetcher = storeFetcher;
this.localDatabase = localDatabase;
this.txPulling = txPulling;
this.connectionStrategy = connectionStrategy;
this.retryStrategy = retryStrategy;
this.copiedStoreRecovery = copiedStoreRecovery;
this.debugLog = debugLogProvider.getLog( getClass() );
this.userLog = userLogProvider.getLog( getClass() );
}
@Override
public void init() throws Throwable
{
localDatabase.init();
txPulling.init();
}
private String issueOf( String operation, int attempt )
{
return format( "Failed attempt %d of %s", attempt, operation );
}
@Override
public void start() throws IOException
{
boolean syncedWithCore = false;
RetryStrategy.Timeout timeout = retryStrategy.newTimeout();
for ( int attempt = 1; attempt <= MAX_ATTEMPTS && !syncedWithCore; attempt++ )
{
MemberId source = findCoreMemberToCopyFrom();
try
{
syncStoreWithCore( source );
syncedWithCore = true;
}
catch ( StoreCopyFailedException e )
{
lastIssue = issueOf( format( "copying store files from %s", source ), attempt );
debugLog.warn( lastIssue );
}
catch ( StreamingTransactionsFailedException e )
{
lastIssue = issueOf( format( "streaming transactions from %s", source ), attempt );
debugLog.warn( lastIssue );
}
catch ( StoreIdDownloadFailedException e )
{
lastIssue = issueOf( format( "getting store id from %s", source ), attempt );
debugLog.warn( lastIssue );
}
try
{
Thread.sleep( timeout.getMillis() );
timeout.increment();
}
catch ( InterruptedException e )
{
Thread.interrupted();
lastIssue = "Interrupted while trying to start read replica";
debugLog.warn( lastIssue );
break;
}
attempt++;
}
if ( !syncedWithCore )
{
userLog.error( lastIssue );
throw new RuntimeException( lastIssue );
}
try
{
localDatabase.start();
txPulling.start();
}
catch ( Throwable e )
{
throw new RuntimeException( e );
}
}
private void syncStoreWithCore( MemberId source ) throws IOException, StoreIdDownloadFailedException,
StoreCopyFailedException, StreamingTransactionsFailedException
{
if ( localDatabase.isEmpty() )
{
debugLog.info( "Local database is empty, attempting to replace with copy from core server %s", source );
debugLog.info( "Finding store id of core server %s", source );
StoreId storeId = storeFetcher.getStoreIdOf( source );
debugLog.info( "Copying store from core server %s", source );
localDatabase.delete();
new CopyStoreSafely( fs, localDatabase, copiedStoreRecovery, debugLog )
.copyWholeStoreFrom( source, storeId, storeFetcher );
debugLog.info( "Restarting local database after copy.", source );
}
else
{
ensureSameStoreIdAs( source );
}
}
private void ensureSameStoreIdAs( MemberId remoteCore ) throws StoreIdDownloadFailedException
{
StoreId localStoreId = localDatabase.storeId();
StoreId remoteStoreId = storeFetcher.getStoreIdOf( remoteCore );
if ( !localStoreId.equals( remoteStoreId ) )
{
throw new IllegalStateException( format( "This read replica cannot join the cluster. " +
"The local database is not empty and has a mismatching storeId: expected %s actual %s.",
remoteStoreId, localStoreId ) );
}
}
private MemberId findCoreMemberToCopyFrom()
{
RetryStrategy.Timeout timeout = retryStrategy.newTimeout();
while ( true )
{
try
{
MemberId memberId = connectionStrategy.coreMember();
debugLog.info( "Server starting, connecting to core server %s", memberId );
return memberId;
}
catch ( CoreMemberSelectionException ex )
{
debugLog.info( "Failed to connect to core server. Retrying in %d ms.", timeout.getMillis() );
LockSupport.parkUntil( timeout.getMillis() + System.currentTimeMillis() );
timeout.increment();
}
}
}
@Override
public void stop() throws Throwable
{
txPulling.stop();
localDatabase.stop();
}
@Override
public void shutdown() throws Throwable
{
txPulling.shutdown();
localDatabase.shutdown();
}
}