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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  package org.apache.mina.common.support;
21  
22  import java.util.ArrayList;
23  import java.util.List;
24  
25  import org.apache.mina.common.IoFuture;
26  import org.apache.mina.common.IoFutureListener;
27  import org.apache.mina.common.IoSession;
28  
29  /**
30   * A default implementation of {@link IoFuture}.
31   *  
32   * @author The Apache MINA Project (dev@mina.apache.org)
33   * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13  7월 2007) $
34   */
35  public class DefaultIoFuture implements IoFuture {
36      private final IoSession session;
37  
38      private final Object lock;
39  
40      private IoFutureListener firstListener;
41  
42      private List<IoFutureListener> otherListeners;
43  
44      private Object result;
45  
46      private boolean ready;
47  
48      /**
49       * Creates a new instance.
50       * 
51       * @param session an {@link IoSession} which is associated with this future
52       */
53      public DefaultIoFuture(IoSession session) {
54          this.session = session;
55          this.lock = this;
56      }
57  
58      public IoSession getSession() {
59          return session;
60      }
61  
62      public void join() {
63          synchronized (lock) {
64              while (!ready) {
65                  try {
66                      lock.wait();
67                  } catch (InterruptedException e) {
68                  }
69              }
70          }
71      }
72  
73      public boolean join(long timeoutMillis) {
74          long startTime = (timeoutMillis <= 0) ? 0 : System.currentTimeMillis();
75          long waitTime = timeoutMillis;
76  
77          synchronized (lock) {
78              if (ready) {
79                  return ready;
80              } else if (waitTime <= 0) {
81                  return ready;
82              }
83  
84              for (;;) {
85                  try {
86                      lock.wait(waitTime);
87                  } catch (InterruptedException e) {
88                  }
89  
90                  if (ready) {
91                      return true;
92                  } else {
93                      waitTime = timeoutMillis
94                              - (System.currentTimeMillis() - startTime);
95                      if (waitTime <= 0) {
96                          return ready;
97                      }
98                  }
99              }
100         }
101     }
102 
103     public boolean isReady() {
104         synchronized (lock) {
105             return ready;
106         }
107     }
108 
109     /**
110      * Sets the result of the asynchronous operation, and mark it as finished.
111      */
112     protected void setValue(Object newValue) {
113         synchronized (lock) {
114             // Allow only once.
115             if (ready) {
116                 return;
117             }
118 
119             result = newValue;
120             ready = true;
121             lock.notifyAll();
122 
123             notifyListeners();
124         }
125     }
126 
127     /**
128      * Returns the result of the asynchronous operation.
129      */
130     protected Object getValue() {
131         synchronized (lock) {
132             return result;
133         }
134     }
135 
136     public void addListener(IoFutureListener listener) {
137         if (listener == null) {
138             throw new NullPointerException("listener");
139         }
140 
141         synchronized (lock) {
142             if (firstListener == null) {
143                 firstListener = listener;
144             } else {
145                 if (otherListeners == null) {
146                     otherListeners = new ArrayList<IoFutureListener>(1);
147                 }
148                 otherListeners.add(listener);
149             }
150             if (ready) {
151                 listener.operationComplete(this);
152             }
153         }
154     }
155 
156     public void removeListener(IoFutureListener listener) {
157         if (listener == null) {
158             throw new NullPointerException("listener");
159         }
160 
161         synchronized (lock) {
162             if (listener == firstListener) {
163                 if (otherListeners != null && !otherListeners.isEmpty()) {
164                     firstListener = otherListeners.remove(0);
165                 } else {
166                     firstListener = null;
167                 }
168             } else if (otherListeners != null) {
169                 otherListeners.remove(listener);
170             }
171         }
172     }
173 
174     private void notifyListeners() {
175         synchronized (lock) {
176             if (firstListener != null) {
177                 firstListener.operationComplete(this);
178                 if (otherListeners != null) {
179                     for (IoFutureListener l : otherListeners) {
180                         l.operationComplete(this);
181                     }
182                 }
183             }
184         }
185     }
186 }