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* Licensed to the Apache Software Foundation (ASF) under one
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* 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.cassandra.locator;
import java.net.InetAddress;
import java.util.*;
import java.util.Map.Entry;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.Table;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.locator.TokenMetadata.Topology;
import org.apache.cassandra.utils.FBUtilities;
import com.google.common.collect.Multimap;
/**
* This Replication Strategy takes a property file that gives the intended
* replication factor in each datacenter. The sum total of the datacenter
* replication factor values should be equal to the keyspace replication
* factor.
* <p/>
* So for example, if the keyspace replication factor is 6, the
* datacenter replication factors could be 3, 2, and 1 - so 3 replicas in
* one datacenter, 2 in another, and 1 in another - totalling 6.
* <p/>
* This class also caches the Endpoints and invalidates the cache if there is a
* change in the number of tokens.
*/
public class NetworkTopologyStrategy extends AbstractReplicationStrategy
{
private final IEndpointSnitch snitch;
private final Map<String, Integer> datacenters;
private static final Logger logger = LoggerFactory.getLogger(NetworkTopologyStrategy.class);
public NetworkTopologyStrategy(String table, TokenMetadata tokenMetadata, IEndpointSnitch snitch, Map<String, String> configOptions) throws ConfigurationException
{
super(table, tokenMetadata, snitch, configOptions);
this.snitch = snitch;
Map<String, Integer> newDatacenters = new HashMap<String, Integer>();
if (configOptions != null)
{
for (Entry<String, String> entry : configOptions.entrySet())
{
String dc = entry.getKey();
if (dc.equalsIgnoreCase("replication_factor"))
throw new ConfigurationException("replication_factor is an option for SimpleStrategy, not NetworkTopologyStrategy");
Integer replicas = Integer.valueOf(entry.getValue());
newDatacenters.put(dc, replicas);
}
}
datacenters = Collections.unmodifiableMap(newDatacenters);
logger.debug("Configured datacenter replicas are {}", FBUtilities.toString(datacenters));
}
/**
* calculate endpoints in one pass through the tokens by tracking our progress in each DC, rack etc.
*/
@SuppressWarnings("serial")
public List<InetAddress> calculateNaturalEndpoints(Token searchToken, TokenMetadata tokenMetadata)
{
Set<InetAddress> replicas = new HashSet<InetAddress>();
// replicas we have found in each DC
Map<String, Set<InetAddress>> dcReplicas = new HashMap<String, Set<InetAddress>>(datacenters.size())
{{
for (Map.Entry<String, Integer> dc : datacenters.entrySet())
put(dc.getKey(), new HashSet<InetAddress>(dc.getValue()));
}};
Topology topology = tokenMetadata.getTopology();
// all endpoints in each DC, so we can check when we have exhausted all the members of a DC
Multimap<String, InetAddress> allEndpoints = topology.getDatacenterEndpoints();
// all racks in a DC so we can check when we have exhausted all racks in a DC
Map<String, Multimap<String, InetAddress>> racks = topology.getDatacenterRacks();
assert !allEndpoints.isEmpty() && !racks.isEmpty() : "not aware of any cluster members";
// tracks the racks we have already placed replicas in
Map<String, Set<String>> seenRacks = new HashMap<String, Set<String>>(datacenters.size())
{{
for (Map.Entry<String, Integer> dc : datacenters.entrySet())
put(dc.getKey(), new HashSet<String>());
}};
// tracks the endpoints that we skipped over while looking for unique racks
// when we relax the rack uniqueness we can append this to the current result so we don't have to wind back the iterator
Map<String, Set<InetAddress>> skippedDcEndpoints = new HashMap<String, Set<InetAddress>>(datacenters.size())
{{
for (Map.Entry<String, Integer> dc : datacenters.entrySet())
put(dc.getKey(), new LinkedHashSet<InetAddress>());
}};
Iterator<Token> tokenIter = TokenMetadata.ringIterator(tokenMetadata.sortedTokens(), searchToken, false);
while (tokenIter.hasNext() && !hasSufficientReplicas(dcReplicas, allEndpoints))
{
Token next = tokenIter.next();
InetAddress ep = tokenMetadata.getEndpoint(next);
String dc = snitch.getDatacenter(ep);
// have we already found all replicas for this dc?
if (!datacenters.containsKey(dc) || hasSufficientReplicas(dc, dcReplicas, allEndpoints))
continue;
// can we skip checking the rack?
if (seenRacks.get(dc).size() == racks.get(dc).keySet().size())
{
dcReplicas.get(dc).add(ep);
replicas.add(ep);
}
else
{
String rack = snitch.getRack(ep);
// is this a new rack?
if (seenRacks.get(dc).contains(rack))
{
skippedDcEndpoints.get(dc).add(ep);
}
else
{
dcReplicas.get(dc).add(ep);
replicas.add(ep);
seenRacks.get(dc).add(rack);
// if we've run out of distinct racks, add the hosts we skipped past already (up to RF)
if (seenRacks.get(dc).size() == racks.get(dc).keySet().size())
{
Iterator<InetAddress> skippedIt = skippedDcEndpoints.get(dc).iterator();
while (skippedIt.hasNext() && !hasSufficientReplicas(dc, dcReplicas, allEndpoints))
{
InetAddress nextSkipped = skippedIt.next();
dcReplicas.get(dc).add(nextSkipped);
replicas.add(nextSkipped);
}
}
}
}
}
return new ArrayList<InetAddress>(replicas);
}
private boolean hasSufficientReplicas(String dc, Map<String, Set<InetAddress>> dcReplicas, Multimap<String, InetAddress> allEndpoints)
{
return dcReplicas.get(dc).size() >= Math.min(allEndpoints.get(dc).size(), getReplicationFactor(dc));
}
private boolean hasSufficientReplicas(Map<String, Set<InetAddress>> dcReplicas, Multimap<String, InetAddress> allEndpoints)
{
for (String dc : datacenters.keySet())
if (!hasSufficientReplicas(dc, dcReplicas, allEndpoints))
return false;
return true;
}
public int getReplicationFactor()
{
int total = 0;
for (int repFactor : datacenters.values())
total += repFactor;
return total;
}
public int getReplicationFactor(String dc)
{
Integer replicas = datacenters.get(dc);
return replicas == null ? 0 : replicas;
}
public Set<String> getDatacenters()
{
return datacenters.keySet();
}
public void validateOptions() throws ConfigurationException
{
for (Entry<String, String> e : this.configOptions.entrySet())
{
if (e.getKey().equalsIgnoreCase("replication_factor"))
throw new ConfigurationException("replication_factor is an option for SimpleStrategy, not NetworkTopologyStrategy");
validateReplicationFactor(e.getValue());
}
}
public Collection<String> recognizedOptions()
{
// We explicitely allow all options
return null;
}
}