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 com.datastax.oss.driver.internal.core.metadata.token;
  
  import com.datastax.oss.driver.api.core.metadata.Node;
  import com.datastax.oss.driver.api.core.metadata.token.Token;
  import com.datastax.oss.driver.shaded.guava.common.annotations.VisibleForTesting;
  import com.datastax.oss.driver.shaded.guava.common.base.Preconditions;
  import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import net.jcip.annotations.ThreadSafe;
  
  @ThreadSafe
  class SimpleReplicationStrategy implements ReplicationStrategy {
  
    private final ReplicationFactor replicationFactor;
  
    SimpleReplicationStrategy(Map<String, String> replicationConfig) {
      this(extractReplicationFactor(replicationConfig));
    }
  
    @VisibleForTesting
    SimpleReplicationStrategy(ReplicationFactor replicationFactor) {
      this.replicationFactor = replicationFactor;
    }
  
    @Override
    public Map<Token, Set<Node>> computeReplicasByToken(
        Map<Token, Node> tokenToPrimary, List<Token> ring) {
  
      int rf = Math.min(replicationFactor.fullReplicas(), ring.size());
  
      ImmutableMap.Builder<Token, Set<Node>> result = ImmutableMap.builder();
      CanonicalNodeSetBuilder replicasBuilder = new CanonicalNodeSetBuilder();
  
      for (int i = 0; i < ring.size(); i++) {
        replicasBuilder.clear();
        for (int j = 0; j < ring.size() && replicasBuilder.size() < rf; j++) {
          replicasBuilder.add(tokenToPrimary.get(getTokenWrapping(i + j, ring)));
        }
        result.put(ring.get(i), replicasBuilder.build());
      }
      return result.build();
    }
  
    private static Token getTokenWrapping(int i, List<Token> ring) {
      return ring.get(i % ring.size());
    }
  
    private static ReplicationFactor extractReplicationFactor(Map<String, String> replicationConfig) {
      String factorString = replicationConfig.get("replication_factor");
      Preconditions.checkNotNull(factorString, "Missing replication factor in " + replicationConfig);
      return ReplicationFactor.fromString(factorString);
    }
  }
  