package org.apache.cassandra.service;
/*
*
* 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.
*
*/
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.List;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.ReadResponse;
import org.apache.cassandra.db.Table;
import org.apache.cassandra.locator.IEndpointSnitch;
import org.apache.cassandra.locator.NetworkTopologyStrategy;
import org.apache.cassandra.net.Message;
import org.apache.cassandra.thrift.ConsistencyLevel;
import org.apache.cassandra.thrift.UnavailableException;
import org.apache.cassandra.utils.FBUtilities;
/**
* Datacenter Quorum response handler blocks for a quorum of responses from the local DC
*/
public class DatacenterReadCallback<T> extends ReadCallback<T>
{
private static final IEndpointSnitch snitch = DatabaseDescriptor.getEndpointSnitch();
private static final String localdc = snitch.getDatacenter(FBUtilities.getBroadcastAddress());
public DatacenterReadCallback(IResponseResolver resolver, ConsistencyLevel consistencyLevel, IReadCommand command, List<InetAddress> endpoints)
{
super(resolver, consistencyLevel, command, endpoints);
}
@Override
protected List<InetAddress> preferredEndpoints(List<InetAddress> endpoints)
{
ArrayList<InetAddress> preferred = new ArrayList<InetAddress>(blockfor);
for (InetAddress endpoint : endpoints)
{
if (localdc.equals(snitch.getDatacenter(endpoint)))
preferred.add(endpoint);
if (preferred.size() == blockfor)
break;
}
return preferred;
}
@Override
protected boolean waitingFor(Message message)
{
return localdc.equals(snitch.getDatacenter(message.getFrom()));
}
@Override
protected boolean waitingFor(ReadResponse response)
{
// cheat and leverage our knowledge that a local read is the only way the ReadResponse
// version of this method gets called
return true;
}
@Override
public int determineBlockFor(ConsistencyLevel consistency_level, String table)
{
NetworkTopologyStrategy stategy = (NetworkTopologyStrategy) Table.open(table).getReplicationStrategy();
return (stategy.getReplicationFactor(localdc) / 2) + 1;
}
@Override
public void assureSufficientLiveNodes() throws UnavailableException
{
int localEndpoints = 0;
for (InetAddress endpoint : endpoints)
{
if (localdc.equals(snitch.getDatacenter(endpoint)))
localEndpoints++;
}
if (localEndpoints < blockfor)
{
if (logger.isDebugEnabled())
{
StringBuilder builder = new StringBuilder("Local replicas [");
for (InetAddress endpoint : endpoints)
{
if (localdc.equals(snitch.getDatacenter(endpoint)))
builder.append(endpoint).append(",");
}
builder.append("] are insufficient to satisfy LOCAL_QUORUM requirement of ").append(blockfor).append(" live nodes in '").append(localdc).append("'");
logger.debug(builder.toString());
}
throw new UnavailableException();
}
}
}