1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19 package org.eclipse.jetty.util;
20
21 import java.io.IOException;
22 import java.util.concurrent.CancellationException;
23 import java.util.concurrent.CountDownLatch;
24 import java.util.concurrent.ExecutionException;
25 import java.util.concurrent.Future;
26 import java.util.concurrent.TimeUnit;
27 import java.util.concurrent.TimeoutException;
28 import java.util.concurrent.atomic.AtomicBoolean;
29
30 public class FuturePromise<C> implements Future<C>,Promise<C>
31 {
32 private static Throwable COMPLETED=new Throwable();
33 private final AtomicBoolean _done=new AtomicBoolean(false);
34 private final CountDownLatch _latch=new CountDownLatch(1);
35 private Throwable _cause;
36 private C _result;
37
38 public FuturePromise()
39 {}
40
41 public FuturePromise(C result)
42 {
43 _cause=COMPLETED;
44 _result=result;
45 _done.set(true);
46 _latch.countDown();
47 }
48
49 public FuturePromise(C ctx, Throwable failed)
50 {
51 _result=ctx;
52 _cause=failed;
53 _done.set(true);
54 _latch.countDown();
55 }
56
57 @Override
58 public void succeeded(C result)
59 {
60 if (_done.compareAndSet(false,true))
61 {
62 _result=result;
63 _cause=COMPLETED;
64 _latch.countDown();
65 }
66 }
67
68 @Override
69 public void failed(Throwable cause)
70 {
71 if (_done.compareAndSet(false,true))
72 {
73 _cause=cause;
74 _latch.countDown();
75 }
76 }
77
78 @Override
79 public boolean cancel(boolean mayInterruptIfRunning)
80 {
81 if (_done.compareAndSet(false,true))
82 {
83 _result=null;
84 _cause=new CancellationException();
85 _latch.countDown();
86 return true;
87 }
88 return false;
89 }
90
91 @Override
92 public boolean isCancelled()
93 {
94 if (_done.get())
95 {
96 try
97 {
98 _latch.await();
99 }
100 catch (InterruptedException e)
101 {
102 throw new RuntimeException(e);
103 }
104 return _cause instanceof CancellationException;
105 }
106 return false;
107 }
108
109 @Override
110 public boolean isDone()
111 {
112 return _done.get() && _latch.getCount()==0;
113 }
114
115 @Override
116 public C get() throws InterruptedException, ExecutionException
117 {
118 _latch.await();
119 if (_cause==COMPLETED)
120 return _result;
121 if (_cause instanceof CancellationException)
122 throw (CancellationException) new CancellationException().initCause(_cause);
123 throw new ExecutionException(_cause);
124 }
125
126 @Override
127 public C get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException
128 {
129 if (!_latch.await(timeout,unit))
130 throw new TimeoutException();
131
132 if (_cause==COMPLETED)
133 return _result;
134 if (_cause instanceof TimeoutException)
135 throw (TimeoutException)_cause;
136 if (_cause instanceof CancellationException)
137 throw (CancellationException) new CancellationException().initCause(_cause);
138 throw new ExecutionException(_cause);
139 }
140
141 public static void rethrow(ExecutionException e) throws IOException
142 {
143 Throwable cause=e.getCause();
144 if (cause instanceof IOException)
145 throw (IOException)cause;
146 if (cause instanceof Error)
147 throw (Error)cause;
148 if (cause instanceof RuntimeException)
149 throw (RuntimeException)cause;
150 throw new RuntimeException(cause);
151 }
152
153 @Override
154 public String toString()
155 {
156 return String.format("FutureCallback@%x{%b,%b,%s}",hashCode(),_done,_cause==COMPLETED,_result);
157 }
158
159 }