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13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
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25 
26 package sun.nio.ch;
27 
28 
29 // Special-purpose data structure for sets of native threads
30 
31 
32 class NativeThreadSet {
33 
34     private long[] elts;
35     private int used = 0;
36     private boolean waitingToEmpty;
37 
NativeThreadSet(int n)38     NativeThreadSet(int n) {
39         elts = new long[n];
40     }
41 
42     // Adds the current native thread to this set, returning its index so that
43     // it can efficiently be removed later.
44     //
add()45     int add() {
46         long th = NativeThread.current();
47         // 0 and -1 are treated as placeholders, not real thread handles
48         if (th == 0)
49             th = -1;
50         synchronized (this) {
51             int start = 0;
52             if (used >= elts.length) {
53                 int on = elts.length;
54                 int nn = on * 2;
55                 long[] nelts = new long[nn];
56                 System.arraycopy(elts, 0, nelts, 0, on);
57                 elts = nelts;
58                 start = on;
59             }
60             for (int i = start; i < elts.length; i++) {
61                 if (elts[i] == 0) {
62                     elts[i] = th;
63                     used++;
64                     return i;
65                 }
66             }
67             assert false;
68             return -1;
69         }
70     }
71 
72     // Removes the thread at the given index.
73     //
remove(int i)74     void remove(int i) {
75         synchronized (this) {
76             elts[i] = 0;
77             used--;
78             if (used == 0 && waitingToEmpty)
79                 notifyAll();
80         }
81     }
82 
83     // Signals all threads in this set.
84     //
signalAndWait()85     synchronized void signalAndWait() {
86         boolean interrupted = false;
87         while (used > 0) {
88             int u = used;
89             int n = elts.length;
90             for (int i = 0; i < n; i++) {
91                 long th = elts[i];
92                 if (th == 0)
93                     continue;
94                 if (th != -1)
95                     NativeThread.signal(th);
96                 if (--u == 0)
97                     break;
98             }
99             waitingToEmpty = true;
100             try {
101                 wait(50);
102             } catch (InterruptedException e) {
103                 interrupted = true;
104             } finally {
105                 waitingToEmpty = false;
106             }
107         }
108         if (interrupted)
109             Thread.currentThread().interrupt();
110     }
111 }
112