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/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.enterprise.config.serverbeans;

import org.jvnet.hk2.config.Element;
import org.jvnet.hk2.config.DuckTyped;
import org.jvnet.hk2.config.ConfigBeanProxy;
import org.jvnet.hk2.config.types.PropertyBag; //used only for Javadoc purpose {@link}
import java.util.List;
import java.beans.PropertyVetoException;

/**
 * Factored out the list of jvm-options from at least two other interfaces that have them: java-config and profiler.
 * Similar to {@link PropertyBag}
 */
public interface JvmOptionBag extends ConfigBeanProxy {
    @Element
    public List getJvmOptions();

    void setJvmOptions(List options) throws PropertyVetoException;

    /**
     * It's observed that many a time we need the value of max heap size. This is useful when deciding if a user is
     * misconfiguring the JVM by specifying -Xmx that is smaller than -Xms. Sun's JVM for example, bails out with
     *  Incompatible minimum and maximum heap sizes specified when that happens. It's generally better to do
     * some basic validations in those cases and that's when this method may be useful.
     *
     * @return an integer specifying the actual max heap memory (-Xmx) configured. If it's specified as -Xmx2g, then 2*1024
     * i.e. 2048 is returned. Returns -1 if no -Xmx is specified.
     */
    @DuckTyped
    int getXmxMegs();

    /**
     * see #getXmxMegs
     *
     * @return integer specifying -Xms in megabytes, or -1
     */
    @DuckTyped
    int getXmsMegs();

    @DuckTyped
    boolean contains(String option);

    @DuckTyped
    String getStartingWith(String start);

    class Duck {
        /* Note: It does not take defaults into account. Also,
        * I have tested that server does not start with a heap that is less than 1m, so I think I don't have to worry about
        * -Xmx that is specified to be less than 1 MB. Again, there is lots and lots of platform dependent code here,
        *  so this check should be minimal. Again, I am doing this kind of check here because while testing, I was
        *  able to get into a situation where -Xmx is configured smaller than -Xms and the server won't start. The user
        *  then must edit the domain.xml by hand!
        */
        public static int getXmxMegs(JvmOptionBag me) {
            return getMemory(me, "-Xmx");
        }

        public static int getXmsMegs(JvmOptionBag me) {
            return getMemory(me, "-Xms");
        }

        private static int getMemory(JvmOptionBag me, String which) {
            List options = me.getJvmOptions();
            for (String opt : options) {
                if (opt.indexOf(which) >= 0) {
                    return toMeg(opt, which);
                }
            }
            return -1;
        }

        public static int toMeg(String whole, String which) {
            String second = whole.substring(which.length());
            char unit = second.charAt(second.length() - 1);
            try {
                if (unit == 'g' || unit == 'G')
                    return Integer.parseInt(second.substring(0, second.length() - 1)) * 1024; //I don't think we'll have an overflow
                else if (unit == 'm' || unit == 'M')
                    return Integer.parseInt(second.substring(0, second.length() - 1));
                else if (unit == 'k' || unit == 'K')
                    return Integer.parseInt(second.substring(0, second.length() - 1)) / 1024; //beware, integer division
                else
                    return Integer.parseInt(second) / (1024 * 1024); //bytes, this is a rare case, hopefully -- who does -Xmx1073741824 to specify a meg?
            } catch (NumberFormatException e) {
                //squelch all exceptions
                return -1;
            } catch (RuntimeException e) {
                //squelch all exceptions
                return -1;
            }
        }

        public static boolean contains(JvmOptionBag me, String opt) {
            return me.getJvmOptions().contains(opt);
        }

        public static String getStartingWith(JvmOptionBag me, String start) {
            List opts = me.getJvmOptions();
            for (String opt : opts) {
                if (opt.startsWith(start))
                    return opt;
            }
            return null;
        }
    }
}