processing/src/main/java/org/apache/druid/query/DefaultQueryConfig.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.query;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.common.collect.ImmutableMap;

import javax.annotation.Nonnull;
import java.util.Map;

/**
 * A user configuration holder for all query types.
 * Any query-specific configurations should go to their own configuration.
 * @see org.apache.druid.query.groupby.GroupByQueryConfig
 * @see org.apache.druid.query.search.SearchQueryConfig
 * @see org.apache.druid.query.topn.TopNQueryConfig
 * @see org.apache.druid.query.metadata.SegmentMetadataQueryConfig
 * @see org.apache.druid.query.scan.ScanQueryConfig
 *
 */
public class DefaultQueryConfig
{
  /**
   * Note that context values should not be directly retrieved from this field but instead should
   * be read through {@link QueryContexts}. This field contains context configs from runtime property
   * which is then merged with configs passed in query context. The result of the merge is subsequently stored in
   * the query context.  The order of precedence in merging of the configs is as follow:
   * runtime property values (store in this class) override by query context parameter passed in with the query
   */
  @JsonProperty
  private final Map<String, Object> context;

  @Nonnull
  public Map<String, Object> getContext()
  {
    return context;
  }

  @JsonCreator
  public DefaultQueryConfig(@JsonProperty("context") Map<String, Object> context)
  {
    if (context == null) {
      this.context = ImmutableMap.of();
    } else {
      this.context = context;
    }
  }
}