com.github.javaclub.cdl.client.matrix.merger.aggregation.AvgAggregationUnit Maven / Gradle / Ivy

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/**
 * Copyright 1999-2015 dangdang.com.
 * 
 * Licensed 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.github.javaclub.cdl.client.matrix.merger.aggregation;

import java.math.BigDecimal;

import com.github.javaclub.cdl.client.matrix.merger.common.ResultSetUtil;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;

/**
 * 平均值聚合单元.
 * 
 * @author gaohongtao
 */
@RequiredArgsConstructor
@Slf4j
public class AvgAggregationUnit extends AbstractAggregationUnit {

	private final Class returnType;

	private BigDecimal count;

	private BigDecimal sum;

	@Override
	public void doMerge(final Comparable... values) {
		if (null == values || null == values[0] || null == values[1]) {
			return;
		}
		if (null == count) {
			count = new BigDecimal("0");
		}
		if (null == sum) {
			sum = new BigDecimal("0");
		}
		count = count.add(new BigDecimal(values[0].toString()));
		sum = sum.add(new BigDecimal(values[1].toString()));
		log.trace("AVG result COUNT: {} SUM: {}", count, sum);
	}

	@Override
	public Comparable getResult() {
		if (null == count || BigDecimal.ZERO.equals(count)) {
			return (Comparable) ResultSetUtil.convertValue(count, returnType);
		}
		// TODO 通过metadata获取数据库的浮点数精度值
		return (Comparable) ResultSetUtil.convertValue(sum.divide(count, 4, BigDecimal.ROUND_HALF_UP), returnType);
	}
}