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Apache Hadoop Common
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/*
 * 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.fs.statistics.impl;

import java.util.Map;

import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;

import org.apache.hadoop.fs.statistics.IOStatistics;
import org.apache.hadoop.fs.statistics.MeanStatistic;

import static org.apache.hadoop.fs.statistics.IOStatisticsLogging.ioStatisticsToString;

/**
 * Wrap IOStatistics source with another (dynamic) wrapper.
 */
public class WrappedIOStatistics extends AbstractIOStatisticsImpl {

  /**
   * The wrapped statistics.
   */
  private IOStatistics wrapped;

  /**
   * Instantiate.
   * @param wrapped nullable wrapped statistics.
   */
  public WrappedIOStatistics(final IOStatistics wrapped) {
    this.wrapped = wrapped;
  }

  /**
   * Instantiate without setting the statistics.
   * This is for subclasses which build up the map during their own
   * construction.
   */
  protected WrappedIOStatistics() {
  }

  @Override
  public Map counters() {
    return getWrapped().counters();
  }

  /**
   * Get at the wrapped inner statistics.
   * @return the wrapped value
   */
  protected IOStatistics getWrapped() {
    return wrapped;
  }

  /**
   * Set the wrapped statistics.
   * Will fail if the field is already set.
   * @param wrapped new value
   */
  protected void setWrapped(final IOStatistics wrapped) {
    Preconditions.checkState(this.wrapped == null,
        "Attempted to overwrite existing wrapped statistics");
    this.wrapped = wrapped;
  }

  @Override
  public Map gauges() {
    return getWrapped().gauges();
  }

  @Override
  public Map minimums() {
    return getWrapped().minimums();
  }

  @Override
  public Map maximums() {
    return getWrapped().maximums();
  }

  @Override
  public Map meanStatistics() {
    return getWrapped().meanStatistics();
  }

  /**
   * Return the statistics dump of the wrapped statistics.
   * @return the statistics for logging.
   */
  @Override
  public String toString() {
    return ioStatisticsToString(wrapped);
  }
}