1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package org.jboss.netty.handler.ssl;
17
18 import javax.net.ssl.SSLEngine;
19 import java.nio.ByteBuffer;
20
21 /**
22 * A {@link ByteBuffer} pool dedicated for {@link SslHandler} performance
23 * improvement.
24 * <p>
25 * In most cases, you won't need to create a new pool instance because
26 * {@link SslHandler} has a default pool instance internally.
27 * <p>
28 * The reason why {@link SslHandler} requires a buffer pool is because the
29 * current {@link SSLEngine} implementation always requires a 17KiB buffer for
30 * every 'wrap' and 'unwrap' operation. In most cases, the actual size of the
31 * required buffer is much smaller than that, and therefore allocating a 17KiB
32 * buffer for every 'wrap' and 'unwrap' operation wastes a lot of memory
33 * bandwidth, resulting in the application performance degradation.
34 */
35 public class SslBufferPool {
36
37 // Add 1024 as a room for compressed data and another 1024 for Apache Harmony compatibility.
38 private static final int MAX_PACKET_SIZE = 16665 + 2048;
39 private static final int DEFAULT_POOL_SIZE = MAX_PACKET_SIZE * 1024;
40
41 private final ByteBuffer[] pool;
42 private final int maxBufferCount;
43 private int index;
44
45 /**
46 * Creates a new buffer pool whose size is {@code 18113536}, which can
47 * hold {@code 1024} buffers.
48 */
49 public SslBufferPool() {
50 this(DEFAULT_POOL_SIZE);
51 }
52
53 /**
54 * Creates a new buffer pool.
55 *
56 * @param maxPoolSize the maximum number of bytes that this pool can hold
57 */
58 public SslBufferPool(int maxPoolSize) {
59 if (maxPoolSize <= 0) {
60 throw new IllegalArgumentException("maxPoolSize: " + maxPoolSize);
61 }
62
63 int maxBufferCount = maxPoolSize / MAX_PACKET_SIZE;
64 if (maxPoolSize % MAX_PACKET_SIZE != 0) {
65 maxBufferCount ++;
66 }
67
68 pool = new ByteBuffer[maxBufferCount];
69 this.maxBufferCount = maxBufferCount;
70 }
71
72 /**
73 * Returns the maximum size of this pool in byte unit. The returned value
74 * can be somewhat different from what was specified in the constructor.
75 */
76 public int getMaxPoolSize() {
77 return maxBufferCount * MAX_PACKET_SIZE;
78 }
79
80 /**
81 * Returns the number of bytes which were allocated but have not been
82 * acquired yet. You can estimate how optimal the specified maximum pool
83 * size is from this value. If it keeps returning {@code 0}, it means the
84 * pool is getting exhausted. If it keeps returns a unnecessarily big
85 * value, it means the pool is wasting the heap space.
86 */
87 public synchronized int getUnacquiredPoolSize() {
88 return index * MAX_PACKET_SIZE;
89 }
90
91 /**
92 * Acquire a new {@link ByteBuffer} out of the {@link SslBufferPool}
93 *
94 */
95 public synchronized ByteBuffer acquireBuffer() {
96 if (index == 0) {
97 return ByteBuffer.allocate(MAX_PACKET_SIZE);
98 } else {
99 return (ByteBuffer) pool[-- index].clear();
100 }
101 }
102
103 /**
104 * Will get removed. Please use {@link #acquireBuffer()}
105 *
106 */
107 @Deprecated
108 ByteBuffer acquire() {
109 return acquireBuffer();
110 }
111
112 /**
113 * Release a previous acquired {@link ByteBuffer}
114 */
115 public synchronized void releaseBuffer(ByteBuffer buffer) {
116 if (index < maxBufferCount) {
117 pool[index ++] = buffer;
118 }
119 }
120
121 /**
122 * @deprecated Use {@link #releaseBuffer(ByteBuffer)}
123 */
124 @Deprecated
125 void release(ByteBuffer buffer) {
126 releaseBuffer(buffer);
127 }
128 }