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 com.ververica.field.dynamicrules.functions;
  
  import org.apache.flink.api.common.functions.AggregateFunction;
  import org.apache.flink.api.java.tuple.Tuple2;
  
  /**
   * The accumulator is used to keep a running sum and a count. The {@code getResult} method computes
   * the average.
   */
  public class AverageAggregate implements AggregateFunction<Long, Tuple2<Long, Long>, Double> {
    @Override
    public Tuple2<Long, Long> createAccumulator() {
      return new Tuple2<>(0L, 0L);
    }
  
    @Override
    public Tuple2<Long, Long> add(Long value, Tuple2<Long, Long> accumulator) {
      return new Tuple2<>(accumulator.f0 + value, accumulator.f1 + 1L);
    }
  
    @Override
    public Double getResult(Tuple2<Long, Long> accumulator) {
      return ((double) accumulator.f0) / accumulator.f1;
    }
  
    @Override
    public Tuple2<Long, Long> merge(Tuple2<Long, Long> a, Tuple2<Long, Long> b) {
      return new Tuple2<>(a.f0 + b.f0, a.f1 + b.f1);
    }
  }
  