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