001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.quotas;
019
020import java.util.Map.Entry;
021import org.apache.hadoop.hbase.client.RegionInfo;
022import org.apache.hadoop.hbase.io.HeapSize;
023import org.apache.yetus.audience.InterfaceAudience;
024
025/**
026 * An interface for concurrently storing and updating the size of a Region.
027 */
028@InterfaceAudience.Private
029public interface RegionSizeStore extends Iterable<Entry<RegionInfo, RegionSize>>, HeapSize {
030
031  /**
032   * Returns the size for the give region if one exists. If no size exists, {@code null} is
033   * returned.
034   * @param regionInfo The region whose size is being fetched.
035   * @return The size in bytes of the region or null if no size is stored.
036   */
037  RegionSize getRegionSize(RegionInfo regionInfo);
038
039  /**
040   * Atomically sets the given {@code size} for a region.
041   * @param regionInfo An identifier for a region.
042   * @param size       The size in bytes of the region.
043   */
044  void put(RegionInfo regionInfo, long size);
045
046  /**
047   * Atomically alter the size of a region.
048   * @param regionInfo The region to update.
049   * @param delta      The change in size for the region, positive or negative.
050   */
051  void incrementRegionSize(RegionInfo regionInfo, long delta);
052
053  /**
054   * Removes the mapping for the given key, returning the value if one exists in the store.
055   * @param regionInfo The key to remove from the store
056   * @return The value removed from the store if one exists, otherwise null.
057   */
058  RegionSize remove(RegionInfo regionInfo);
059
060  /**
061   * Returns the number of entries in the store.
062   * @return The number of entries in the store.
063   */
064  int size();
065
066  /**
067   * Returns if the store is empty.
068   * @return true if there are no entries in the store, otherwise false.
069   */
070  boolean isEmpty();
071
072  /**
073   * Removes all entries from the store.
074   */
075  void clear();
076}