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20 package org.apache.mina.filter;
21
22 import java.util.Iterator;
23 import java.util.List;
24
25 import org.apache.mina.common.ByteBuffer;
26 import org.apache.mina.common.DefaultIoFilterChainBuilder;
27 import org.apache.mina.common.IoFilterAdapter;
28 import org.apache.mina.common.IoFilterChain;
29 import org.apache.mina.common.IoSession;
30 import org.apache.mina.common.IoFilterChain.Entry;
31 import org.apache.mina.filter.executor.ExecutorFilter;
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62 public class ReadThrottleFilterBuilder {
63 public static final String COUNTER = ReadThrottleFilterBuilder.class
64 .getName()
65 + ".counter";
66
67 public static final String SUSPENDED_READS = ReadThrottleFilterBuilder.class
68 .getName()
69 + ".suspendedReads";
70
71 private volatile int maximumConnectionBufferSize = 1024 * 1024;
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80 public void setMaximumConnectionBufferSize(int maximumConnectionBufferSize) {
81 this.maximumConnectionBufferSize = maximumConnectionBufferSize;
82 }
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90 public void attach(IoFilterChain chain) {
91 String name = getThreadPoolFilterEntryName(chain.getAll());
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93 chain.addBefore(name, getClass().getName() + ".add", new Add());
94 chain.addAfter(name, getClass().getName() + ".release", new Release());
95 }
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103 public void attach(DefaultIoFilterChainBuilder builder) {
104 String name = getThreadPoolFilterEntryName(builder.getAll());
105
106 builder.addBefore(name, getClass().getName() + ".add", new Add());
107 builder
108 .addAfter(name, getClass().getName() + ".release",
109 new Release());
110 }
111
112 private String getThreadPoolFilterEntryName(List<Entry> entries) {
113 Iterator<Entry> i = entries.iterator();
114
115 while (i.hasNext()) {
116 IoFilterChain.Entry entry = i.next();
117
118 if (entry.getFilter().getClass().isAssignableFrom(
119 ExecutorFilter.class)) {
120 return entry.getName();
121 }
122 }
123
124 throw new IllegalStateException(
125 "Chain does not contain a ExecutorFilter");
126 }
127
128 private void add(IoSession session, int size) {
129 synchronized (session) {
130 int counter = getCounter(session) + size;
131
132 session.setAttribute(COUNTER, new Integer(counter));
133
134 if (counter >= maximumConnectionBufferSize
135 && session.getTrafficMask().isReadable()) {
136 session.suspendRead();
137 session.setAttribute(SUSPENDED_READS);
138 }
139 }
140 }
141
142 private void release(IoSession session, int size) {
143 synchronized (session) {
144 int counter = Math.max(0, getCounter(session) - size);
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146 session.setAttribute(COUNTER, new Integer(counter));
147
148 if (counter < maximumConnectionBufferSize
149 && isSuspendedReads(session)) {
150 session.resumeRead();
151 session.removeAttribute(SUSPENDED_READS);
152 }
153
154 }
155 }
156
157 private boolean isSuspendedReads(IoSession session) {
158 Boolean flag = (Boolean) session.getAttribute(SUSPENDED_READS);
159
160 return null != flag && flag.booleanValue();
161 }
162
163 private int getCounter(IoSession session) {
164 Integer i = (Integer) session.getAttribute(COUNTER);
165 return null == i ? 0 : i.intValue();
166 }
167
168 private class Add extends IoFilterAdapter {
169 public void messageReceived(NextFilter nextFilter, IoSession session,
170 Object message) throws Exception {
171 if (message instanceof ByteBuffer) {
172 add(session, ((ByteBuffer) message).remaining());
173 }
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175 nextFilter.messageReceived(session, message);
176 }
177 }
178
179 private class Release extends IoFilterAdapter {
180 public void messageReceived(NextFilter nextFilter, IoSession session,
181 Object message) throws Exception {
182 if (message instanceof ByteBuffer) {
183 release(session, ((ByteBuffer) message).remaining());
184 }
185
186 nextFilter.messageReceived(session, message);
187 }
188 }
189 }