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1   /*
2    * Copyright 2009 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * 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.util.internal;
17  
18  import java.util.ArrayList;
19  import java.util.List;
20  import java.util.regex.Pattern;
21  
22  import org.jboss.netty.channel.DefaultChannelPipeline;
23  import org.jboss.netty.channel.SimpleChannelHandler;
24  import org.jboss.netty.channel.StaticChannelPipeline;
25  import org.jboss.netty.util.DebugUtil;
26  import org.jboss.netty.util.ThreadRenamingRunnable;
27  
28  /**
29   * Simplifies an exception stack trace by removing unnecessary
30   * {@link StackTraceElement}s.  Please note that the stack trace simplification
31   * is disabled if {@linkplain DebugUtil debug mode} is turned on.
32   *
33   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
34   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
35   *
36   * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
37   *
38   */
39  public class StackTraceSimplifier {
40  
41      private static final boolean SIMPLIFY_STACK_TRACE = !DebugUtil.isDebugEnabled();
42      private static final Pattern EXCLUDED_STACK_TRACE =
43          Pattern.compile(
44                  "^org\\.jboss\\.netty\\." +
45                  "(util\\.(ThreadRenamingRunnable|internal\\.DeadLockProofWorker)" +
46                  "|channel\\.(SimpleChannel(Upstream|Downstream)?Handler|(Default|Static)ChannelPipeline.*))(\\$.*)?$");
47  
48      /**
49       * Removes unnecessary {@link StackTraceElement}s from the specified
50       * exception. {@link ThreadRenamingRunnable}, {@link SimpleChannelHandler},
51       * {@link DefaultChannelPipeline}, and {@link StaticChannelPipeline}
52       * will be dropped from the trace.
53       */
54      public static void simplify(Throwable e) {
55          if (!SIMPLIFY_STACK_TRACE) {
56              return;
57          }
58  
59          if (e.getCause() != null) {
60              simplify(e.getCause());
61          }
62  
63          StackTraceElement[] trace = e.getStackTrace();
64          if (trace == null || trace.length == 0) {
65              return;
66          }
67  
68          // Perhaps Netty bug.  Let us not strip things out.
69          if (EXCLUDED_STACK_TRACE.matcher(trace[0].getClassName()).matches()) {
70              return;
71          }
72  
73          List<StackTraceElement> simpleTrace =
74              new ArrayList<StackTraceElement>(trace.length);
75  
76          simpleTrace.add(trace[0]);
77  
78          // Remove unnecessary stack trace elements.
79          for (int i = 1; i < trace.length; i ++) {
80              if (EXCLUDED_STACK_TRACE.matcher(trace[i].getClassName()).matches()) {
81                  continue;
82              }
83              simpleTrace.add(trace[i]);
84          }
85  
86          e.setStackTrace(
87                  simpleTrace.toArray(new StackTraceElement[simpleTrace.size()]));
88      }
89  }