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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.regionserver;
19  
20  import java.util.Collection;
21  
22  import org.apache.hadoop.conf.Configured;
23  import org.apache.hadoop.hbase.classification.InterfaceAudience;
24  
25  /**
26   * A flush policy determines the stores that need to be flushed when flushing a region.
27   */
28  @InterfaceAudience.Private
29  public abstract class FlushPolicy extends Configured {
30  
31    /**
32     * The region configured for this flush policy.
33     */
34    protected HRegion region;
35  
36    /**
37     * Upon construction, this method will be called with the region to be governed. It will be called
38     * once and only once.
39     */
40    protected void configureForRegion(HRegion region) {
41      this.region = region;
42    }
43  
44    /**
45     * @return the stores need to be flushed.
46     */
47    public abstract Collection<Store> selectStoresToFlush();
48  
49  }