core/src/test/java/org/apache/calcite/test/FoodMartQuerySet.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.calcite.test;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.SoftReference;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/** Set of queries against the FoodMart database. */
public class FoodMartQuerySet {
  private static SoftReference<FoodMartQuerySet> ref;

  public final Map<Integer, FoodmartQuery> queries = new LinkedHashMap<>();

  private FoodMartQuerySet() throws IOException {
    final ObjectMapper mapper = new ObjectMapper();
    mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
    mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);

    final InputStream inputStream =
        new net.hydromatic.foodmart.queries.FoodmartQuerySet().getQueries();
    FoodmartRoot root = mapper.readValue(inputStream, FoodmartRoot.class);
    for (FoodmartQuery query : root.queries) {
      queries.put(query.id, query);
    }
  }

  /** Returns the singleton instance of the query set. It is backed by a
   * soft reference, so it may be freed if memory is short and no one is
   * using it. */
  public static synchronized FoodMartQuerySet instance() throws IOException {
    final SoftReference<FoodMartQuerySet> refLocal = ref;
    if (refLocal != null) {
      final FoodMartQuerySet set = refLocal.get();
      if (set != null) {
        return set;
      }
    }
    final FoodMartQuerySet set = new FoodMartQuerySet();
    ref = new SoftReference<>(set);
    return set;
  }

  /** JSON root element. */
  public static class FoodmartRoot {
    public final List<FoodmartQuery> queries = new ArrayList<>();
  }

  /** JSON query element. */
  @JsonIgnoreProperties(value = {"columns", "rows"})
  public static class FoodmartQuery {
    public int id;
    public String sql;

    @Override public String toString() {
      return "id=" + id;
    }
  }
}