1/*
2 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
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).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package sun.net;
27
28import java.net.SocketException;
29import java.util.concurrent.atomic.AtomicInteger;
30import 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
40public 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
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
77    public static void afterUdpClose() {
78        if (System.getSecurityManager() != null) {
79            numSockets.decrementAndGet();
80        }
81    }
82}
83