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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.IdentityHashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.cassandra.dht.IPartitioner;
  import org.apache.cassandra.dht.Range;
  import org.apache.cassandra.dht.Token;
  import org.apache.cassandra.tcm.ClusterMetadata;
  import org.apache.cassandra.tcm.Epoch;
  import org.apache.cassandra.tcm.ownership.DataPlacement;
  import org.apache.cassandra.tcm.ownership.ReplicaGroups;
  import org.apache.cassandra.tcm.ownership.VersionedEndpoints;
  import org.apache.cassandra.utils.FBUtilities;
  
  public class LocalStrategy extends SystemStrategy
  {
      private static final ReplicationFactor RF = ReplicationFactor.fullOnly(1);
      private static final Map<IPartitioner, EntireRange> perPartitionerRanges = new IdentityHashMap<>();
  
      public LocalStrategy(String keyspaceName, Map<String, String> configOptions)
      {
          super(keyspaceName, configOptions);
      }
  
      @Override
      public EndpointsForRange calculateNaturalReplicas(Token token, ClusterMetadata metadata)
      {
          return getRange(token.getPartitioner()).localReplicas;
      }
  
      @Override
      public DataPlacement calculateDataPlacement(Epoch epoch, List<Range<Token>> ranges, ClusterMetadata metadata)
      {
          return getRange(ranges.get(0).left.getPartitioner()).placement;
      }
  
      @Override
      public ReplicationFactor getReplicationFactor()
      {
          return RF;
      }
  
      private EntireRange getRange(IPartitioner partitioner)
      {
          return perPartitionerRanges.computeIfAbsent(partitioner, EntireRange::new);
      }
  
      /**
       * For lazy initialisation. In some circumstances, we may want to instantiate LocalStrategy without initialising
       * DatabaseDescriptor; FQL replay is one such usage as we initialise the KeyspaceMetadata objects, which now eagerly
       * creates the replication strategy.
       */
      static class EntireRange
      {
          public final Range<Token> entireRange;
          public final EndpointsForRange localReplicas;
          public final DataPlacement placement;
  
          private EntireRange(IPartitioner partitioner)
          {
              entireRange = new Range<>(partitioner.getMinimumToken(), partitioner.getMinimumToken());
              localReplicas = EndpointsForRange.of(new Replica(FBUtilities.getBroadcastAddressAndPort(), entireRange, true));
              ReplicaGroups rg = ReplicaGroups.builder(1).withReplicaGroup(VersionedEndpoints.forRange(Epoch.FIRST, localReplicas)).build();
              placement = new DataPlacement(rg, rg);
          }
      }
  }
  