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.loadbalancing.helper;
  
  import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
  import com.datastax.oss.driver.api.core.config.DriverExecutionProfile;
  import com.datastax.oss.driver.api.core.metadata.Node;
  import com.datastax.oss.driver.internal.core.context.InternalDriverContext;
  import com.datastax.oss.driver.internal.core.metadata.DefaultNode;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Set;
  import java.util.UUID;
  import net.jcip.annotations.ThreadSafe;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * An implementation of {@link LocalDcHelper} that fetches the user-supplied datacenter, if any,
   * from the programmatic configuration API, or else, from the driver configuration. If no local
   * datacenter is explicitly defined, this implementation will consider two distinct situations:
   *
   * <ol>
   *   <li>If no explicit contact points were provided, this implementation will infer the local
   *       datacenter from the implicit contact point (localhost).
   *   <li>If explicit contact points were provided however, this implementation will throw {@link
   *       IllegalStateException}.
   * </ol>
   */
  @ThreadSafe
  public class MandatoryLocalDcHelper extends OptionalLocalDcHelper {
  
    private static final Logger LOG = LoggerFactory.getLogger(MandatoryLocalDcHelper.class);
  
    public MandatoryLocalDcHelper(
        @NonNull InternalDriverContext context,
        @NonNull DriverExecutionProfile profile,
        @NonNull String logPrefix) {
      super(context, profile, logPrefix);
    }
  
    /** @return The local datacenter; always present. */
    @NonNull
    @Override
    public Optional<String> discoverLocalDc(@NonNull Map<UUID, Node> nodes) {
      Optional<String> optionalLocalDc = super.discoverLocalDc(nodes);
      if (optionalLocalDc.isPresent()) {
        return optionalLocalDc;
      }
      Set<DefaultNode> contactPoints = context.getMetadataManager().getContactPoints();
      if (context.getMetadataManager().wasImplicitContactPoint()) {
        // We only allow automatic inference of the local DC in this specific case
        assert contactPoints.size() == 1;
        Node contactPoint = contactPoints.iterator().next();
        String localDc = contactPoint.getDatacenter();
        if (localDc != null) {
          LOG.debug(
              "[{}] Local DC set from implicit contact point {}: {}",
              logPrefix,
              contactPoint,
              localDc);
          return Optional.of(localDc);
        } else {
          throw new IllegalStateException(
              "The local DC could not be inferred from implicit contact point, please set it explicitly (see "
                  + DefaultDriverOption.LOAD_BALANCING_LOCAL_DATACENTER.getPath()
                  + " in the config, or set it programmatically with SessionBuilder.withLocalDatacenter)");
        }
      } else {
        throw new IllegalStateException(
            "Since you provided explicit contact points, the local DC must be explicitly set (see "
                + DefaultDriverOption.LOAD_BALANCING_LOCAL_DATACENTER.getPath()
                + " in the config, or set it programmatically with SessionBuilder.withLocalDatacenter). "
                + "Current contact points are: "
                + formatNodesAndDcs(contactPoints)
                + ". Current DCs in this cluster are: "
                + formatDcs(nodes.values()));
      }
    }
  }
  