1 /*
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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
9  * by Oracle in the LICENSE file that accompanied this code.
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11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 = GetPropertyAction
57                 .privilegedGetProperty("sun.net.maxDatagramSockets");
58         int defmax = DEFAULT_MAX_SOCKETS;
59         try {
60             if (prop != null) {
61                 defmax = Integer.parseInt(prop);
62             }
63         } catch (NumberFormatException e) {}
64         maxSockets = defmax;
65         numSockets = new AtomicInteger(0);
66     }
67 
beforeUdpCreate()68     public static void beforeUdpCreate() throws SocketException {
69         if (System.getSecurityManager() != null) {
70             if (numSockets.incrementAndGet() > maxSockets) {
71                 numSockets.decrementAndGet();
72                 throw new SocketException("maximum number of DatagramSockets reached");
73             }
74         }
75     }
76 
afterUdpClose()77     public static void afterUdpClose() {
78         if (System.getSecurityManager() != null) {
79             numSockets.decrementAndGet();
80         }
81     }
82 }
83