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1
4 package com.tc.util;
5
6 import com.tc.net.EphemeralPorts;
7 import com.tc.net.EphemeralPorts.Range;
8
9 import java.io.IOException  ;
10 import java.net.BindException ;
11 import java.net.ServerSocket ;
12 import java.util.HashSet ;
13 import java.util.Random ;
14 import java.util.Set ;
15
16 public final class PortChooser {
17 private static final Object VM_WIDE_LOCK = (PortChooser.class.getName() + "LOCK").intern();
18 private static final Set chosen = new HashSet ();
19 private static final Random random = new Random ();
20 private static final Range exclude = EphemeralPorts.getRange();
21
22 public int chooseRandomPort() {
23 synchronized (VM_WIDE_LOCK) {
24 return choose();
25 }
26 }
27
28 private int choose() {
29 while (true) {
30 final Integer attempt = new Integer (getNonEphemeralPort());
31 boolean added = chosen.add(attempt);
32 if (!added) {
33 continue; }
35
36 ServerSocket ss = null;
37 try {
38 int port = attempt.intValue();
39 ss = new ServerSocket (port);
40 return port;
41 } catch (BindException be) {
42 continue; } catch (IOException e) {
44 throw new RuntimeException (e);
45 } finally {
46 if (ss != null) {
47 while (!ss.isClosed()) {
48 try {
49 ss.close();
50 } catch (IOException e) {
51 }
53 }
54 }
55 }
56 }
57 }
58
59 private static int getNonEphemeralPort() {
60 while (true) {
61 int p = random.nextInt(65535 - 1024) + 1024;
62 if (p < exclude.getLower() || p > exclude.getUpper()) { return p; }
63 }
64 }
65
66 }
67 |
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