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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 org.jboss.netty.channel.ChannelFuture;
19  
20  /**
21   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
22   * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
23   */
24  public class IoWorkerRunnable implements Runnable {
25  
26      /**
27       * An <em>internal use only</em> thread-local variable that determines if
28       * the caller is running on an I/O worker thread, which is the case where
29       * the caller enters a dead lock if the caller calls
30       * {@link ChannelFuture#await()} or {@link ChannelFuture#awaitUninterruptibly()}.
31       */
32      public static final ThreadLocal<Boolean> IN_IO_THREAD = new ThreadLocalBoolean();
33  
34      private final Runnable runnable;
35  
36      public IoWorkerRunnable(Runnable runnable) {
37          if (runnable == null) {
38              throw new NullPointerException("runnable");
39          }
40          this.runnable = runnable;
41      }
42  
43      public void run() {
44          IN_IO_THREAD.set(Boolean.TRUE);
45          try {
46              runnable.run();
47          } finally {
48              IN_IO_THREAD.remove();
49          }
50      }
51  }