View Javadoc

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  
19  package org.apache.hadoop.hbase.regionserver;
20  
21  import java.io.IOException;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  import org.apache.hadoop.hbase.monitoring.MonitoredTask;
25  
26  /**
27   * A package protected interface for a store flushing.
28   * A store flush context carries the state required to prepare/flush/commit the store's cache.
29   */
30  @InterfaceAudience.Private
31  interface StoreFlushContext {
32  
33    /**
34     * Prepare for a store flush (create snapshot)
35     *
36     * Requires pausing writes.
37     *
38     * A very short operation.
39     */
40    void prepare();
41  
42    /**
43     * Flush the cache (create the new store file)
44     *
45     * A length operation which doesn't require locking out any function
46     * of the store.
47     *
48     * @throws IOException in case the flush fails
49     */
50    void flushCache(MonitoredTask status) throws IOException;
51  
52    /**
53     * Commit the flush - add the store file to the store and clear the
54     * memstore snapshot.
55     *
56     * Requires pausing scans.
57     *
58     * A very short operation
59     *
60     * @return
61     * @throws IOException
62     */
63    boolean commit(MonitoredTask status) throws IOException;
64  }