services/src/main/java/org/apache/druid/server/router/TieredBrokerSelectorStrategy.java

/*
 * 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.druid.server.router;

import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.google.common.base.Optional;
import org.apache.druid.query.Query;
import org.apache.druid.sql.http.SqlQuery;

/**
 */
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
@JsonSubTypes(value = {
    @JsonSubTypes.Type(name = "timeBoundary", value = TimeBoundaryTieredBrokerSelectorStrategy.class),
    @JsonSubTypes.Type(name = "priority", value = PriorityTieredBrokerSelectorStrategy.class),
    @JsonSubTypes.Type(name = "manual", value = ManualTieredBrokerSelectorStrategy.class),
    @JsonSubTypes.Type(name = "javascript", value = JavaScriptTieredBrokerSelectorStrategy.class)
})

public interface TieredBrokerSelectorStrategy
{

  /**
   * Tries to determine the name of the Broker service to which the given native
   * query should be routed.
   *
   * @param config Config containing tier to broker service map
   * @param query  Native (JSON) query to be routed
   * @return An empty Optional if the service name could not be determined.
   */
  Optional<String> getBrokerServiceName(TieredBrokerConfig config, Query query);

  /**
   * Tries to determine the name of the Broker service to which the given SqlQuery
   * should be routed. The default implementation returns an empty Optional.
   *
   * @param config   Config containing tier to broker service map
   * @param sqlQuery SQL query to be routed
   * @return An empty Optional if the service name could not be determined.
   */
  default Optional<String> getBrokerServiceName(TieredBrokerConfig config, SqlQuery sqlQuery)
  {
    return Optional.absent();
  }
}