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1
50 package org.apache.avalon.excalibur.concurrent;
51
52
65 public class Semaphore
66 implements Sync
67 {
68 private long m_tokens;
69
70
76 public Semaphore( final long tokens )
77 {
78 m_tokens = tokens;
79 }
80
81 public synchronized void acquire()
82 throws InterruptedException 
83 {
84 if( Thread.interrupted() ) throw new InterruptedException ();
86
87 while( 0 >= m_tokens )
89 {
90 wait();
91 }
92 m_tokens--;
93 }
94
95 public synchronized void release()
96 {
97 m_tokens++;
98 notify();
99 }
100
101 public synchronized boolean attempt( final long msecs )
102 throws InterruptedException
103 {
104 if( Thread.interrupted() ) throw new InterruptedException ();
105
106 if( m_tokens > 0 )
107 {
108 m_tokens--;
109 return true;
110 }
111 else
112 {
113 final long start = System.currentTimeMillis();
114 long wait = msecs;
115
116 while( wait > 0 )
117 {
118 wait( wait );
119
120 if( m_tokens > 0 )
121 {
122 m_tokens--;
123 return true;
124 }
125 else
126 {
127 wait = msecs - ( System.currentTimeMillis() - start );
128 }
129 }
130
131 return false;
132 }
133 }
134 }
135 |
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