content: /*
   * 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.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.config.DatabaseDescriptor;
  import org.apache.cassandra.db.guardrails.Guardrails;
  import org.apache.cassandra.dht.Range;
  import org.apache.cassandra.dht.Token;
  import org.apache.cassandra.exceptions.ConfigurationException;
  import org.apache.cassandra.schema.SchemaConstants;
  import org.apache.cassandra.service.ClientState;
  import org.apache.cassandra.service.ClientWarn;
  import org.apache.cassandra.service.StorageService;
  import org.apache.cassandra.tcm.ClusterMetadata;
  import org.apache.cassandra.tcm.Epoch;
  import org.apache.cassandra.tcm.compatibility.TokenRingUtils;
  import org.apache.cassandra.tcm.membership.Directory;
  import org.apache.cassandra.tcm.membership.NodeId;
  import org.apache.cassandra.tcm.ownership.DataPlacement;
  import org.apache.cassandra.tcm.ownership.ReplicaGroups;
  import org.apache.cassandra.tcm.ownership.TokenMap;
  import org.apache.cassandra.tcm.ownership.VersionedEndpoints;
  
  /**
   * This class returns the nodes responsible for a given
   * key but does not respect rack awareness. Basically
   * returns the RF nodes that lie right next to each other
   * on the ring.
   */
  public class SimpleStrategy extends AbstractReplicationStrategy
  {
      public static final String REPLICATION_FACTOR = "replication_factor";
  
      private static final Logger logger = LoggerFactory.getLogger(SimpleStrategy.class);
      private final ReplicationFactor rf;
  
      public SimpleStrategy(String keyspaceName, Map<String, String> configOptions)
      {
          super(keyspaceName, configOptions);
          validateOptionsInternal(configOptions);
          this.rf = ReplicationFactor.fromString(this.configOptions.get(REPLICATION_FACTOR));
      }
  
  
      @Override
      public DataPlacement calculateDataPlacement(Epoch epoch, List<Range<Token>> ranges, ClusterMetadata metadata)
      {
          ReplicaGroups.Builder builder = ReplicaGroups.builder();
          for (Range<Token> range : ranges)
              builder.withReplicaGroup(VersionedEndpoints.forRange(epoch,
                                                                   calculateNaturalReplicas(range.right, metadata.tokenMap.tokens(), range, metadata.directory, metadata.tokenMap)));
  
          ReplicaGroups built = builder.build();
          return new DataPlacement(built, built);
      }
  
      @Override
      public EndpointsForRange calculateNaturalReplicas(Token token, ClusterMetadata metadata)
      {
          List<Token> ring = metadata.tokenMap.tokens();
          if (ring.isEmpty())
              return EndpointsForRange.empty(new Range<>(metadata.tokenMap.partitioner().getMinimumToken(), metadata.tokenMap.partitioner().getMinimumToken()));
  
          Range<Token> replicaRange = TokenRingUtils.getRange(ring, token);
          return calculateNaturalReplicas(token, ring, replicaRange, metadata.directory, metadata.tokenMap);
      }
  
      private EndpointsForRange calculateNaturalReplicas(Token token,
                                                         List<Token> ring,
                                                         Range<Token> replicaRange,
                                                         Directory endpoints,
                                                         TokenMap tokens)
      {
          if (ring.isEmpty())
              return EndpointsForRange.empty(new Range<>(tokens.partitioner().getMinimumToken(), token.getPartitioner().getMinimumToken()));
  
          Iterator<Token> iter = TokenRingUtils.ringIterator(ring, token, false);
  
          EndpointsForRange.Builder replicas = new EndpointsForRange.Builder(replicaRange, rf.allReplicas);
  
          // Add the token at the index by default
          while (replicas.size() < rf.allReplicas && iter.hasNext())
          {
              Token tk = iter.next();
              NodeId owner = tokens.owner(tk);
              InetAddressAndPort ep = endpoints.endpoint(owner);
              if (!replicas.endpoints().contains(ep))
                  replicas.add(new Replica(ep, replicaRange, replicas.size() < rf.fullReplicas));
          }
  
          return replicas.build();
      }
  
  
      @Override
      public ReplicationFactor getReplicationFactor()
      {
          return rf;
      }
  
      private static void validateOptionsInternal(Map<String, String> configOptions) throws ConfigurationException
      {
          if (configOptions.get(REPLICATION_FACTOR) == null)
              throw new ConfigurationException("SimpleStrategy requires a replication_factor strategy option.");
      }
  
      @Override
      public void validateOptions() throws ConfigurationException
      {
          validateOptionsInternal(configOptions);
          validateReplicationFactor(configOptions.get(REPLICATION_FACTOR));
      }
  
      @Override
      public void maybeWarnOnOptions(ClientState state)
      {
          if (!SchemaConstants.isSystemKeyspace(keyspaceName))
          {
              int nodeCount = StorageService.instance.getHostIdToEndpoint().size();
              // nodeCount==0 on many tests
              Guardrails.minimumReplicationFactor.guard(rf.fullReplicas, keyspaceName, false, state);
              Guardrails.maximumReplicationFactor.guard(rf.fullReplicas, keyspaceName, false, state);
              if (rf.fullReplicas > nodeCount && nodeCount != 0)
              {
                  String msg = "Your replication factor " + rf.fullReplicas
                               + " for keyspace "
                               + keyspaceName
                               + " is higher than the number of nodes "
                               + nodeCount;
                  ClientWarn.instance.warn(msg);
                  logger.warn(msg);
              }
          }
      }
  
      @Override
      public Collection<String> recognizedOptions(ClusterMetadata metadata)
      {
          return Collections.singleton(REPLICATION_FACTOR);
      }
  
      @SuppressWarnings("unused") // used via reflection
      protected static void prepareOptions(Map<String, String> options, Map<String, String> previousOptions)
      {
          // When altering from NTS to SS, previousOptions could have multiple different RFs for different data centers - so we
          // will instead default to DefaultRF configuration if RF is not mentioned with the alter statement
          String rf = previousOptions.containsKey(REPLICATION_FACTOR) ? previousOptions.get(REPLICATION_FACTOR)
                                                                      : Integer.toString(DatabaseDescriptor.getDefaultKeyspaceRF());
          options.putIfAbsent(REPLICATION_FACTOR, rf);
      }
  }
  