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/* * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.net; import java.net.SocketException;import java.util.concurrent.atomic.AtomicInteger;import sun.security.action.GetPropertyAction; /** * Manages count of total number of UDP sockets and ensures * that exception is thrown if we try to create more than the * configured limit. * * This functionality could be put in NetHooks some time in future. */ public class ResourceManager {     /* default maximum number of udp sockets per VM     * when a security manager is enabled.     * The default is 1024 which is high enough to be useful     * but low enough to be well below the maximum number     * of port numbers actually available on all OSes for     * such sockets (5000 on some versions of windows)     */     private static final int DEFAULT_MAX_SOCKETS = 1024;    private static final int maxSockets;    private static final AtomicInteger numSockets;     static {        String prop = java.security.AccessController.doPrivileged(            new GetPropertyAction("sun.net.maxDatagramSockets")        );        int defmax = DEFAULT_MAX_SOCKETS;        try {            if (prop != null) {                defmax = Integer.parseInt(prop);            }        } catch (NumberFormatException e) {}        maxSockets = defmax;        numSockets = new AtomicInteger(0);    }     public static void beforeUdpCreate() throws SocketException {        if (System.getSecurityManager() != null) {            if (numSockets.incrementAndGet() > maxSockets) {                numSockets.decrementAndGet();                throw new SocketException("maximum number of DatagramSockets reached");            }        }    }     public static void afterUdpClose() {        if (System.getSecurityManager() != null) {            numSockets.decrementAndGet();        }    }}