/*
 * 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.hadoop.hive.ql.exec;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.apache.hadoop.io.LongWritable;

public class Stat {

  // stored stats
  private final Map<String, LongWritable> statsMap;

  // additional bookkeeping info for the stored stats
  private final Map<String, Integer> bookkeepingInfo;

  public Stat() {
    statsMap = new HashMap<String, LongWritable>();
    bookkeepingInfo = new HashMap<String, Integer>();
  }

  public void addToStat(String statType, long amount) {
    LongWritable currentValue = statsMap.get(statType);
    if (currentValue == null) {
      statsMap.put(statType, new LongWritable(amount));
    } else {
      currentValue.set(currentValue.get() + amount);
    }
  }

  public long getStat(String statType) {
    LongWritable currValue = statsMap.get(statType);
    if (currValue == null) {
      return 0;
    }
    return currValue.get();
  }

  public Collection<String> getStoredStats() {
    return statsMap.keySet();
  }

  public void clear() {
    statsMap.clear();
  }

  // additional information about stats (e.g., virtual column number

  public void setBookkeepingInfo(String statType, int info) {
    bookkeepingInfo.put(statType, info);
  }

  public int getBookkeepingInfo(String statType) {
    Integer info = bookkeepingInfo.get(statType);
    if (info == null) {
      return -1;
    }
    return info.intValue();
  }

}
