geode-core/src/main/java/org/apache/geode/cache/query/internal/aggregate/DistinctAggregator.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.geode.cache.query.internal.aggregate;

import java.util.HashSet;
import java.util.Set;

import org.apache.geode.cache.query.QueryService;

/**
 * The class used to hold the distinct values. This will get instantiated on the bucket node as part
 * of distinct queries for sum, count, average.
 */
public class DistinctAggregator extends AbstractAggregator {
  protected final Set<Object> distinct;

  Set<Object> getDistinct() {
    return distinct;
  }

  public DistinctAggregator() {
    this.distinct = new HashSet<>();
  }

  @Override
  public void init() {}

  @Override
  public void accumulate(Object value) {
    if (value != null && value != QueryService.UNDEFINED) {
      this.distinct.add(value);
    }
  }

  @Override
  public Object terminate() {
    return this.distinct;
  }
}