/*
 * 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.hbase.quotas;

import java.util.Iterator;
import java.util.Map.Entry;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.yetus.audience.InterfaceAudience;

/**
 * A {@link RegionSizeStore} implementation that stores nothing.
 */
@InterfaceAudience.Private
public final class NoOpRegionSizeStore implements RegionSizeStore {
  private static final NoOpRegionSizeStore INSTANCE = new NoOpRegionSizeStore();

  private NoOpRegionSizeStore() {
  }

  @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "MS_EXPOSE_REP",
      justification = "singleton pattern")
  public static NoOpRegionSizeStore getInstance() {
    return INSTANCE;
  }

  @Override
  public Iterator<Entry<RegionInfo, RegionSize>> iterator() {
    return null;
  }

  @Override
  public long heapSize() {
    return 0;
  }

  @Override
  public RegionSize getRegionSize(RegionInfo regionInfo) {
    return null;
  }

  @Override
  public void put(RegionInfo regionInfo, long size) {
  }

  @Override
  public void incrementRegionSize(RegionInfo regionInfo, long delta) {
  }

  @Override
  public RegionSize remove(RegionInfo regionInfo) {
    return null;
  }

  @Override
  public int size() {
    return 0;
  }

  @Override
  public boolean isEmpty() {
    return true;
  }

  @Override
  public void clear() {
  }
}
