/*

 * Copyright (c) 2013, 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.

 *

 * 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.

 */

import java.io.File;

import java.io.FileWriter;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import java.util.Arrays;

import java.util.stream.Collectors;

import java.lang.management.ManagementFactory;

import javax.management.MalformedObjectNameException;

import javax.management.ObjectName;

public class NMTHelper

{

    public static void baseline() {

        executeDcmd("vmNativeMemory", "baseline");

    }

    // Total: reserved=3484685KB +293KB, committed=266629KB +293KB

    private static Pattern totalLine = Pattern.compile("^Total: reserved=\\d+KB .*KB, committed=\\d+KB (.*)KB$");

    public static long committedDiff() throws Exception {

        String res = (String) executeDcmd("vmNativeMemory", "detail.diff");

        String[] lines = res.split("\n");

        for (String line : lines) {

            Matcher matcher = totalLine.matcher(line);

            if (matcher.matches()) {

                String committed = matcher.group(1);

                return Long.parseLong(committed);

            }

        }

        throw new Exception("Could not find the Total line in the NMT output.");

    }

    private static String executeDcmd(String cmd, String ... args) {

        ObjectName oname = null;

        try {

            oname = ObjectName.getInstance("com.sun.management:type=DiagnosticCommand");

        } catch (MalformedObjectNameException mone) {

            throw new RuntimeException(mone);

        }

        Object[] dcmdArgs = {args};

        String[] signature = {String[].class.getName()};

        String cmdString = cmd + " " +

            Arrays.stream(args).collect(Collectors.joining(" "));

        File f = new File("dcmdoutput-" + cmd + "-" + System.currentTimeMillis() + ".txt");

        System.out.println("Output from Dcmd '" + cmdString + "' is being written to file " + f);

        try (FileWriter fw = new FileWriter(f)) {

            fw.write("> " + cmdString + ":");

            String result = (String)ManagementFactory.getPlatformMBeanServer().

                    invoke(oname, cmd, dcmdArgs, signature);

            fw.write(result);

            return result;

        } catch(Exception ex) {

            ex.printStackTrace();

        }

        return null;

    }

}