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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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8  * particular file as subject to the "Classpath" exception as provided
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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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24  */
25 
26 package sun.net;
27 
28 import java.net.SocketException;
29 import java.util.concurrent.atomic.AtomicInteger;
30 import sun.security.action.GetPropertyAction;
31 
32 /**
33  * Manages count of total number of UDP sockets and ensures
34  * that exception is thrown if we try to create more than the
35  * configured limit.
36  *
37  * This functionality could be put in NetHooks some time in future.
38  */
39 
40 public class ResourceManager {
41 
42     /* default maximum number of udp sockets per VM
43      * when a security manager is enabled.
44      * The default is 25 which is high enough to be useful
45      * but low enough to be well below the maximum number
46      * of port numbers actually available on all OSes
47      * when multiplied by the maximum feasible number of VM processes
48      * that could practically be spawned.
49      */
50 
51     private static final int DEFAULT_MAX_SOCKETS = 25;
52     private static final int maxSockets;
53     private static final AtomicInteger numSockets;
54 
55     static {
56         String prop = java.security.AccessController.doPrivileged(
57             new GetPropertyAction("sun.net.maxDatagramSockets")
58         );
59         int defmax = DEFAULT_MAX_SOCKETS;
60         try {
61             if (prop != null) {
62                 defmax = Integer.parseInt(prop);
63             }
64         } catch (NumberFormatException e) {}
65         maxSockets = defmax;
66         numSockets = new AtomicInteger(0);
67     }
68 
beforeUdpCreate()69     public static void beforeUdpCreate() throws SocketException {
70         if (System.getSecurityManager() != null) {
71             if (numSockets.incrementAndGet() > maxSockets) {
72                 numSockets.decrementAndGet();
73                 throw new SocketException("maximum number of DatagramSockets reached");
74             }
75         }
76     }
77 
afterUdpClose()78     public static void afterUdpClose() {
79         if (System.getSecurityManager() != null) {
80             numSockets.decrementAndGet();
81         }
82     }
83 }
84