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 import org.apache.hadoop.hbase.util.ByteBufferArray;
26
27 /**
28 * IO engine that stores data in memory using an array of ByteBuffers
29 * {@link ByteBufferArray}
30 */
31 @InterfaceAudience.Private
32 public class ByteBufferIOEngine implements IOEngine {
33 private ByteBufferArray bufferArray;
34 private final long capacity;
35 private final boolean direct;
36
37 /**
38 * Construct the ByteBufferIOEngine with the given capacity
39 * @param capacity
40 * @param direct true if allocate direct buffer
41 * @throws IOException
42 */
43 public ByteBufferIOEngine(long capacity, boolean direct)
44 throws IOException {
45 this.capacity = capacity;
46 this.direct = direct;
47 bufferArray = new ByteBufferArray(capacity, direct);
48 }
49
50 @Override
51 public String toString() {
52 return "ioengine=" + this.getClass().getSimpleName() + ", capacity=" +
53 String.format("%,d", this.capacity) + ", direct=" + this.direct;
54 }
55
56 /**
57 * Memory IO engine is always unable to support persistent storage for the
58 * cache
59 * @return false
60 */
61 @Override
62 public boolean isPersistent() {
63 return false;
64 }
65
66 /**
67 * Transfers data from the buffer array to the given byte buffer
68 * @param dstBuffer the given byte buffer into which bytes are to be written
69 * @param offset The offset in the ByteBufferArray of the first byte to be
70 * read
71 * @return number of bytes read
72 * @throws IOException
73 */
74 @Override
75 public int read(ByteBuffer dstBuffer, long offset) throws IOException {
76 assert dstBuffer.hasArray();
77 return bufferArray.getMultiple(offset, dstBuffer.remaining(), dstBuffer.array(),
78 dstBuffer.arrayOffset());
79 }
80
81 /**
82 * Transfers data from the given byte buffer to the buffer array
83 * @param srcBuffer the given byte buffer from which bytes are to be read
84 * @param offset The offset in the ByteBufferArray of the first byte to be
85 * written
86 * @throws IOException
87 */
88 @Override
89 public void write(ByteBuffer srcBuffer, long offset) throws IOException {
90 assert srcBuffer.hasArray();
91 bufferArray.putMultiple(offset, srcBuffer.remaining(), srcBuffer.array(),
92 srcBuffer.arrayOffset());
93 }
94
95 /**
96 * No operation for the sync in the memory IO engine
97 */
98 @Override
99 public void sync() {
100 // Nothing to do.
101 }
102
103 /**
104 * No operation for the shutdown in the memory IO engine
105 */
106 @Override
107 public void shutdown() {
108 // Nothing to do.
109 }
110 }