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 org.apache.kafka.streams.query;
  
  import org.apache.kafka.common.annotation.InterfaceStability.Evolving;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.stream.Collectors;
  
  /**
   * The response object for interactive queries. This wraps the individual partition results, as well
   * as metadata relating to the result as a whole.
   * <p>
   *
   * @param <R> The type of the query result.
   */
  @Evolving
  public class StateQueryResult<R> {
  
      private final Map<Integer, QueryResult<R>> partitionResults = new HashMap<>();
      private QueryResult<R> globalResult = null;
  
      /**
       * Set the result for a global store query. Used by Kafka Streams and available for tests.
       */
      public void setGlobalResult(final QueryResult<R> r) {
          this.globalResult = r;
      }
  
      /**
       * Set the result for a partitioned store query. Used by Kafka Streams and available for tests.
       */
      public void addResult(final int partition, final QueryResult<R> r) {
          partitionResults.put(partition, r);
      }
  
  
      /**
       * The query's result for each partition that executed the query. Empty for global store
       * queries.
       */
      public Map<Integer, QueryResult<R>> getPartitionResults() {
          return partitionResults;
      }
  
      /**
       * For queries that are expected to match records in only one partition, returns the result.
       *
       * @throws IllegalArgumentException if the results are not for exactly one partition.
       */
      public QueryResult<R> getOnlyPartitionResult() {
          final List<QueryResult<R>> nonempty =
              partitionResults
                  .values()
                  .stream()
                  .filter(QueryResult::isSuccess)
                  .filter(r -> r.getResult() != null)
                  .collect(Collectors.toList());
  
          if (nonempty.size() > 1) {
              throw new IllegalArgumentException(
                  "The query did not return exactly one partition result: " + partitionResults
              );
          } else {
              return nonempty.isEmpty() ? null : nonempty.get(0);
          }
      }
  
      /**
       * The query's result for global store queries. Is {@code null} for non-global (partitioned)
       * store queries.
       */
      public QueryResult<R> getGlobalResult() {
          return globalResult;
      }
  
      /**
       * The position of the state store at the moment it executed the query. In conjunction with
       * {@link StateQueryRequest#withPositionBound}, this can be used to achieve a good balance
       * between consistency and availability in which repeated queries are guaranteed to advance in
       * time while allowing reads to be served from any replica that is caught up to that caller's
       * prior observations.
       */
      public Position getPosition() {
          if (globalResult != null) {
              return globalResult.getPosition();
          } else {
              final Position position = Position.emptyPosition();
              for (final QueryResult<R> r : partitionResults.values()) {
                  position.merge(r.getPosition());
              }
              return position;
          }
      }
  
      @Override
      public String toString() {
          return "StateQueryResult{" +
              "partitionResults=" + partitionResults +
              ", globalResult=" + globalResult +
              '}';
      }
  }
  