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BatchingMessageHandler.java
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BatchingMessageHandler.java
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/*
* 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 <http://www.gnu.org/licenses/>.
*/
package org.neo4j.coreedge.raft;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import org.neo4j.coreedge.catchup.storecopy.LocalDatabase;
import org.neo4j.coreedge.raft.RaftMessages.RaftMessage;
import org.neo4j.coreedge.raft.net.Inbound.MessageHandler;
import org.neo4j.coreedge.server.StoreId;
import org.neo4j.logging.Log;
import org.neo4j.logging.LogProvider;
import static java.util.concurrent.TimeUnit.SECONDS;
public class BatchingMessageHandler implements Runnable, MessageHandler<RaftMessages.StoreIdAwareMessage>, MismatchedStoreIdService
{
private final Log log;
private final MessageHandler<RaftMessage> innerHandler;
private final BlockingQueue<RaftMessages.StoreIdAwareMessage> messageQueue;
private final int maxBatch;
private final List<RaftMessages.RaftMessage> batch;
private final LocalDatabase localDatabase;
private RaftStateMachine raftStateMachine;
private final List<MismatchedStoreListener> listeners = new ArrayList<>( );
public BatchingMessageHandler( MessageHandler<RaftMessage> innerHandler, LogProvider logProvider,
int queueSize, int maxBatch, LocalDatabase localDatabase,
RaftStateMachine raftStateMachine )
{
this.innerHandler = innerHandler;
this.localDatabase = localDatabase;
this.raftStateMachine = raftStateMachine;
this.log = logProvider.getLog( getClass() );
this.maxBatch = maxBatch;
this.batch = new ArrayList<>( maxBatch );
this.messageQueue = new ArrayBlockingQueue<>( queueSize );
}
@Override
public void handle( RaftMessages.StoreIdAwareMessage message )
{
try
{
messageQueue.put( message );
}
catch ( InterruptedException e )
{
log.warn( "Not expecting to be interrupted.", e );
}
}
@Override
public void run()
{
RaftMessages.StoreIdAwareMessage message = null;
try
{
message = messageQueue.poll( 1, SECONDS );
}
catch ( InterruptedException e )
{
log.warn( "Not expecting to be interrupted.", e );
}
if ( message != null )
{
RaftMessages.RaftMessage innerMessage = message.message();
StoreId storeId = message.storeId();
if ( message.storeId().equals( localDatabase.storeId() ) )
{
if ( messageQueue.isEmpty() )
{
innerHandler.handle( message.message() );
}
else
{
batch.clear();
batch.add( innerMessage );
drain( messageQueue, batch, maxBatch - 1 );
collateAndHandleBatch( batch );
}
}
else
{
if ( localDatabase.isEmpty() )
{
raftStateMachine.downloadSnapshot( innerMessage.from() );
}
else
{
log.info( "Discarding message owing to mismatched storeId and non-empty store. " +
"Expected: %s, Encountered: %s", storeId, localDatabase.storeId() );
listeners.forEach( l -> {
MismatchedStoreIdException ex = new MismatchedStoreIdException( storeId, localDatabase.storeId() );
l.onMismatchedStore( ex );
} );
}
}
}
}
private void drain( BlockingQueue<RaftMessages.StoreIdAwareMessage> messageQueue,
List<RaftMessage> batch, int maxElements )
{
List<RaftMessages.StoreIdAwareMessage> tempDraining = new ArrayList<>();
messageQueue.drainTo( tempDraining, maxElements );
for ( RaftMessages.StoreIdAwareMessage storeIdAwareMessage : tempDraining )
{
batch.add( storeIdAwareMessage.message() );
}
}
public void addMismatchedStoreListener( BatchingMessageHandler.MismatchedStoreListener listener )
{
listeners.add(listener);
}
private void collateAndHandleBatch( List<RaftMessages.RaftMessage> batch )
{
RaftMessages.NewEntry.Batch batchRequest = null;
for ( RaftMessages.RaftMessage message : batch )
{
if ( message instanceof RaftMessages.NewEntry.Request )
{
RaftMessages.NewEntry.Request newEntryRequest = (RaftMessages.NewEntry.Request) message;
if ( batchRequest == null )
{
batchRequest = new RaftMessages.NewEntry.Batch( batch.size() );
}
batchRequest.add( newEntryRequest.content() );
}
else
{
innerHandler.handle( message );
}
}
if ( batchRequest != null )
{
innerHandler.handle( batchRequest );
}
}
}