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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

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/*
 * 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.
 */
package org.apache.cassandra.locator;

import java.util.Collections;
import java.util.Collection;
import java.util.Map;

import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.dht.RingPosition;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.utils.FBUtilities;

public class LocalStrategy extends AbstractReplicationStrategy
{
    private static final ReplicationFactor RF = ReplicationFactor.fullOnly(1);
    private final EndpointsForRange replicas;

    public LocalStrategy(String keyspaceName, TokenMetadata tokenMetadata, IEndpointSnitch snitch, Map configOptions)
    {
        super(keyspaceName, tokenMetadata, snitch, configOptions);
        replicas = EndpointsForRange.of(
                new Replica(FBUtilities.getBroadcastAddressAndPort(),
                        DatabaseDescriptor.getPartitioner().getMinimumToken(),
                        DatabaseDescriptor.getPartitioner().getMinimumToken(),
                        true
                )
        );
    }

    /**
     * We need to override this even if we override calculateNaturalReplicas,
     * because the default implementation depends on token calculations but
     * LocalStrategy may be used before tokens are set up.
     */
    @Override
    public EndpointsForRange getNaturalReplicas(RingPosition searchPosition)
    {
        return replicas;
    }

    public EndpointsForRange calculateNaturalReplicas(Token token, TokenMetadata metadata)
    {
        return replicas;
    }

    public ReplicationFactor getReplicationFactor()
    {
        return RF;
    }

    public void validateOptions() throws ConfigurationException
    {
    }

    @Override
    public void maybeWarnOnOptions()
    {
    }

    @Override
    public Collection recognizedOptions()
    {
        // LocalStrategy doesn't expect any options.
        return Collections.emptySet();
    }
}