001/*
002 * This file is part of McIDAS-V
003 *
004 * Copyright 2007-2016
005 * Space Science and Engineering Center (SSEC)
006 * University of Wisconsin - Madison
007 * 1225 W. Dayton Street, Madison, WI 53706, USA
008 * https://www.ssec.wisc.edu/mcidas
009 * 
010 * All Rights Reserved
011 * 
012 * McIDAS-V is built on Unidata's IDV and SSEC's VisAD libraries, and
013 * some McIDAS-V source code is based on IDV and VisAD source code.  
014 * 
015 * McIDAS-V is free software; you can redistribute it and/or modify
016 * it under the terms of the GNU Lesser Public License as published by
017 * the Free Software Foundation; either version 3 of the License, or
018 * (at your option) any later version.
019 * 
020 * McIDAS-V is distributed in the hope that it will be useful,
021 * but WITHOUT ANY WARRANTY; without even the implied warranty of
022 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
023 * GNU Lesser Public License for more details.
024 * 
025 * You should have received a copy of the GNU Lesser Public License
026 * along with this program.  If not, see http://www.gnu.org/licenses.
027 */
028
029package edu.wisc.ssec.mcidasv.util;
030
031import java.lang.management.ManagementFactory;
032import java.lang.management.OperatingSystemMXBean;
033import java.lang.reflect.Method;
034
035/**
036 * Wrapper for OperatingSystemMXBean.
037 *
038 * <p>Note: this class is likely to be used in contexts where we don't
039 * have logging set up, so {@link System#err} and {@link System#out} are used.
040 */
041public class GetMem {
042
043    /**
044     * Call a method belonging to {@link OperatingSystemMXBean} and return 
045     * the result. 
046     * 
047     * @param <T> Type of the expected return and {@code defaultValue}.
048     * @param methodName Name of {@code OperatingSystemMXBean} method to call.
049     *                   Cannot be {@code null} or empty.
050     * @param defaultValue Value returned if {@code methodName} call fails.
051     * 
052     * @return Either the value returned by the {@code methodName} call, or
053     * {@code defaultValue}.
054     */
055    private <T> T callMXBeanMethod(final String methodName,
056                                   final T defaultValue)
057    {
058        assert methodName != null : "Cannot invoke a null method name";
059        assert methodName.length() > 0: "Cannot invoke an empty method name";
060        OperatingSystemMXBean osBean = 
061            ManagementFactory.getOperatingSystemMXBean();
062        T result = defaultValue;
063        try {
064            Method m = osBean.getClass().getMethod(methodName);
065            m.setAccessible(true);
066            // don't suppress warnings because we cannot guarantee that this
067            // cast is correct.
068            result = (T)m.invoke(osBean);
069        } catch (Exception e) {
070            System.err.println("Error invoking OperatingSystemMXBean method: " + methodName);
071            // do nothing else for right now
072        }
073        return result;
074    }
075
076    /**
077     * Get total system memory and print it out--accounts for 32bit JRE 
078     * limitation of 1.5GB.
079     * 
080     * @return {@code String} representation of the total amount of system 
081     * memory.
082     */
083    public static String getMemory() {
084        GetMem nonStaticInstance = new GetMem();
085        Object totalMemoryObject =
086            nonStaticInstance.callMXBeanMethod("getTotalPhysicalMemorySize", 0);
087        long totalMemory = ((Number)totalMemoryObject).longValue();
088        boolean is64 = System.getProperty("os.arch").contains("64");
089        int megabytes = Math.round(totalMemory / 1024 / 1024);
090        if (!is64 && (megabytes > 1536)) {
091            megabytes = 1536;
092        }
093        return String.valueOf(megabytes);
094    }
095
096    /**
097     * The main. Get total system memory and print it out.
098     * 
099     * @param args Ignored.
100     */
101    public static void main(String[] args) {
102        try {
103            System.out.println(getMemory());
104        } catch (Exception e) {
105            System.err.println("Error getting total physical memory size");
106            System.out.println("0");
107        }
108    }
109}