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.regionserver;
019
020import java.io.IOException;
021import java.util.List;
022import org.apache.yetus.audience.InterfaceAudience;
023
024/**
025 * If set of MapFile.Readers in Store change, implementors are notified.
026 */
027@InterfaceAudience.Private
028public interface ChangedReadersObserver {
029
030  /** Returns the read point of the current scan */
031  long getReadPoint();
032
033  /**
034   * Notify observers. <br/>
035   * NOTE:Before we invoke this method,{@link HStoreFile#increaseRefCount} is invoked for every
036   * {@link HStoreFile} in 'sfs' input parameter to prevent {@link HStoreFile} is archived after a
037   * concurrent compaction, and after this method is invoked,{@link HStoreFile#decreaseRefCount} is
038   * invoked.So if you open the {@link StoreFileReader} or {@link StoreFileScanner} asynchronously
039   * in this method,you may need to invoke {@link HStoreFile#increaseRefCount} or
040   * {@link HStoreFile#decreaseRefCount} by yourself to prevent the {@link HStoreFile}s be archived.
041   * @param sfs              The new files
042   * @param memStoreScanners scanner of current memstore
043   * @throws IOException e
044   */
045  void updateReaders(List<HStoreFile> sfs, List<KeyValueScanner> memStoreScanners)
046    throws IOException;
047}