/*
 * 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
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 */

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.
/**
 * 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 25 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
     * when multiplied by the maximum feasible number of VM processes
     * that could practically be spawned.
     */

    private static final int DEFAULT_MAX_SOCKETS = 25;
    private static final int maxSockets;
    private static final AtomicInteger numSockets;

    static {
        String prop = GetPropertyAction
                .privilegedGetProperty("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();
        }
    }
}