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 java.nio.ByteBuffer;
19
20 import javax.net.ssl.SSLEngine;
21
22 /**
23 * A {@link ByteBuffer} pool dedicated for {@link SslHandler} performance
24 * improvement.
25 * <p>
26 * In most cases, you won't need to create a new pool instance because
27 * {@link SslHandler} has a default pool instance internally.
28 * <p>
29 * The reason why {@link SslHandler} requires a buffer pool is because the
30 * current {@link SSLEngine} implementation always requires a 17KiB buffer for
31 * every 'wrap' and 'unwrap' operation. In most cases, the actual size of the
32 * required buffer is much smaller than that, and therefore allocating a 17KiB
33 * buffer for every 'wrap' and 'unwrap' operation wastes a lot of memory
34 * bandwidth, resulting in the application performance degradation.
35 */
36 public class SslBufferPool {
37
38 // Add 1024 as a room for compressed data and another 1024 for Apache Harmony compatibility.
39 private static final int MAX_PACKET_SIZE = 16665 + 2048;
40 private static final int DEFAULT_POOL_SIZE = MAX_PACKET_SIZE * 1024;
41
42 private final ByteBuffer[] pool;
43 private final int maxBufferCount;
44 private int index;
45
46 /**
47 * Creates a new buffer pool whose size is {@code 18113536}, which can
48 * hold {@code 1024} buffers.
49 */
50 public SslBufferPool() {
51 this(DEFAULT_POOL_SIZE);
52 }
53
54 /**
55 * Creates a new buffer pool.
56 *
57 * @param maxPoolSize the maximum number of bytes that this pool can hold
58 */
59 public SslBufferPool(int maxPoolSize) {
60 if (maxPoolSize <= 0) {
61 throw new IllegalArgumentException("maxPoolSize: " + maxPoolSize);
62 }
63
64 int maxBufferCount = maxPoolSize / MAX_PACKET_SIZE;
65 if (maxPoolSize % MAX_PACKET_SIZE != 0) {
66 maxBufferCount ++;
67 }
68
69 pool = new ByteBuffer[maxBufferCount];
70 this.maxBufferCount = maxBufferCount;
71 }
72
73 /**
74 * Returns the maximum size of this pool in byte unit. The returned value
75 * can be somewhat different from what was specified in the constructor.
76 */
77 public int getMaxPoolSize() {
78 return maxBufferCount * MAX_PACKET_SIZE;
79 }
80
81 /**
82 * Returns the number of bytes which were allocated but have not been
83 * acquired yet. You can estimate how optimal the specified maximum pool
84 * size is from this value. If it keeps returning {@code 0}, it means the
85 * pool is getting exhausted. If it keeps returns a unnecessarily big
86 * value, it means the pool is wasting the heap space.
87 */
88 public synchronized int getUnacquiredPoolSize() {
89 return index * MAX_PACKET_SIZE;
90 }
91
92 /**
93 * Acquire a new {@link ByteBuffer} out of the {@link SslBufferPool}
94 *
95 */
96 public ByteBuffer acquireBuffer() {
97 return acquire();
98 }
99
100 /**
101 * Will get removed. Please use {@link #acquireBuffer()}
102 *
103 */
104 @Deprecated
105 synchronized ByteBuffer acquire() {
106 if (index == 0) {
107 return ByteBuffer.allocate(MAX_PACKET_SIZE);
108 } else {
109 return (ByteBuffer) pool[-- index].clear();
110 }
111 }
112
113
114 /**
115 * Release a previous acquired {@link ByteBuffer}
116 *
117 * @param buffer
118 */
119 public void releaseBuffer(ByteBuffer buffer) {
120 release(buffer);
121 }
122
123 /**
124 * Will get removed. Please use {@link #releaseBuffer(ByteBuffer)}
125 *
126 * @deprecated
127 *
128 */
129 @Deprecated
130 synchronized void release(ByteBuffer buffer) {
131 if (index < maxBufferCount) {
132 pool[index ++] = buffer;
133 }
134 }
135 }