1 /**
2 * Copyright The Apache Software Foundation
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one or more
5 * contributor license agreements. See the NOTICE file distributed with this
6 * work for additional information regarding copyright ownership. The ASF
7 * licenses this file to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance with the License.
9 * 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, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
16 * License for the specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.hadoop.hbase.io.hfile.bucket;
20
21 import java.io.IOException;
22 import java.nio.ByteBuffer;
23
24 import org.apache.hadoop.hbase.classification.InterfaceAudience;
25
26 /**
27 * A class implementing IOEngine interface supports data services for
28 * {@link BucketCache}.
29 */
30 @InterfaceAudience.Private
31 public interface IOEngine {
32 /**
33 * @return true if persistent storage is supported for the cache when shutdown
34 */
35 boolean isPersistent();
36
37 /**
38 * Transfers data from IOEngine to the given byte buffer
39 * @param dstBuffer the given byte buffer into which bytes are to be written
40 * @param offset The offset in the IO engine where the first byte to be read
41 * @return number of bytes read
42 * @throws IOException
43 */
44 int read(ByteBuffer dstBuffer, long offset) throws IOException;
45
46 /**
47 * Transfers data from the given byte buffer to IOEngine
48 * @param srcBuffer the given byte buffer from which bytes are to be read
49 * @param offset The offset in the IO engine where the first byte to be
50 * written
51 * @throws IOException
52 */
53 void write(ByteBuffer srcBuffer, long offset) throws IOException;
54
55 /**
56 * Sync the data to IOEngine after writing
57 * @throws IOException
58 */
59 void sync() throws IOException;
60
61 /**
62 * Shutdown the IOEngine
63 */
64 void shutdown();
65 }