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.loadbalancing.NodeDistance;
  import com.datastax.oss.driver.api.core.loadbalancing.NodeDistanceEvaluator;
  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.util.Reflection;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.util.Map;
  import java.util.UUID;
  import java.util.function.Predicate;
  import net.jcip.annotations.ThreadSafe;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A {@link NodeDistanceEvaluatorHelper} implementation that fetches the user-supplied evaluator, if
   * any, from the programmatic configuration API, or else, from the driver configuration. If no
   * user-supplied evaluator can be retrieved, a dummy evaluator will be used which always evaluates
   * null distances.
   */
  @ThreadSafe
  public class DefaultNodeDistanceEvaluatorHelper implements NodeDistanceEvaluatorHelper {
  
    private static final Logger LOG =
        LoggerFactory.getLogger(DefaultNodeDistanceEvaluatorHelper.class);
  
    @NonNull protected final InternalDriverContext context;
    @NonNull protected final DriverExecutionProfile profile;
    @NonNull protected final String logPrefix;
  
    public DefaultNodeDistanceEvaluatorHelper(
        @NonNull InternalDriverContext context,
        @NonNull DriverExecutionProfile profile,
        @NonNull String logPrefix) {
      this.context = context;
      this.profile = profile;
      this.logPrefix = logPrefix;
    }
  
    @NonNull
    @Override
    public NodeDistanceEvaluator createNodeDistanceEvaluator(
        @Nullable String localDc, @NonNull Map<UUID, Node> nodes) {
      NodeDistanceEvaluator nodeDistanceEvaluatorFromConfig = nodeDistanceEvaluatorFromConfig();
      return (node, dc) -> {
        NodeDistance distance = nodeDistanceEvaluatorFromConfig.evaluateDistance(node, dc);
        if (distance != null) {
          LOG.debug("[{}] Evaluator assigned distance {} to node {}", logPrefix, distance, node);
        } else {
          LOG.debug("[{}] Evaluator did not assign a distance to node {}", logPrefix, node);
        }
        return distance;
      };
    }
  
    @NonNull
    protected NodeDistanceEvaluator nodeDistanceEvaluatorFromConfig() {
      NodeDistanceEvaluator evaluator = context.getNodeDistanceEvaluator(profile.getName());
      if (evaluator != null) {
        LOG.debug("[{}] Node distance evaluator set programmatically", logPrefix);
      } else {
        evaluator =
            Reflection.buildFromConfig(
                    context,
                    profile.getName(),
                    DefaultDriverOption.LOAD_BALANCING_DISTANCE_EVALUATOR_CLASS,
                    NodeDistanceEvaluator.class)
                .orElse(null);
        if (evaluator != null) {
          LOG.debug("[{}] Node distance evaluator set from configuration", logPrefix);
        } else {
          @SuppressWarnings({"unchecked", "deprecation"})
          Predicate<Node> nodeFilterFromConfig =
              Reflection.buildFromConfig(
                      context,
                      profile.getName(),
                      DefaultDriverOption.LOAD_BALANCING_FILTER_CLASS,
                      Predicate.class)
                  .orElse(null);
          if (nodeFilterFromConfig != null) {
            evaluator = new NodeFilterToDistanceEvaluatorAdapter(nodeFilterFromConfig);
            LOG.debug(
                "[{}] Node distance evaluator set from deprecated node filter configuration",
                logPrefix);
          }
        }
      }
      if (evaluator == null) {
        evaluator = PASS_THROUGH_DISTANCE_EVALUATOR;
      }
      return evaluator;
    }
  }
  