1 /*
2 * Copyright 2010 The Apache Software Foundation
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 */
19
20 package org.apache.hadoop.hbase.regionserver;
21
22 import java.io.IOException;
23
24 import org.apache.hadoop.hbase.monitoring.MonitoredTask;
25
26 /**
27 * A package protected interface for a store flushing.
28 * A store flusher carries the state required to prepare/flush/commit the
29 * store's cache.
30 */
31 interface StoreFlusher {
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() throws IOException;
64 }