DetectionUtils.java

/**
 * This file is part of Waarp Project.
 * 
 * Copyright 2009, Frederic Bregier, and individual contributors by the @author tags. See the
 * COPYRIGHT.txt in the distribution for a full listing of individual contributors.
 * 
 * All Waarp Project is free software: you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 * 
 * Waarp 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 for more details.
 * 
 * You should have received a copy of the GNU General Public License along with Waarp . If not, see
 * <http://www.gnu.org/licenses/>.
 */
package org.waarp.common.utility;

import io.netty.util.internal.SystemPropertyUtil;

import java.util.Queue;
import java.util.concurrent.BlockingQueue;

/**
 * Utility that detects various properties specific to the current runtime environment, such as Java
 * version.
 * 
 * @author "Frederic Bregier"
 * 
 */
public class DetectionUtils {
    private static final int JAVA_VERSION = javaVersion0();
    private static final boolean IS_WINDOWS;
    private static final boolean IS_UNIX_IBM;
    private static final int NUMBERTHREAD;

    static {
        String os = SystemPropertyUtil.get("os.name").toLowerCase();
        // windows
        IS_WINDOWS = os.indexOf("win") >= 0;
        if (!IS_WINDOWS) {
            String vendor = SystemPropertyUtil.get("java.vm.vendor");
            vendor = vendor.toLowerCase();
            IS_UNIX_IBM = (vendor.indexOf("ibm") >= 0);
        } else {
            IS_UNIX_IBM = false;
        }
        NUMBERTHREAD = Math.max(1, SystemPropertyUtil.getInt(
                "org.waarp.numThreads", Runtime.getRuntime().availableProcessors() * 2));
    }

    /**
     * 
     * @return the default number of threads (core * 2)
     */
    public static int numberThreads() {
        return NUMBERTHREAD;
    }

    /**
     * Return <code>true</code> if the JVM is running on Windows
     * 
     */
    public static boolean isWindows() {
        return IS_WINDOWS;
    }

    /**
     * Return <code>true</code> if the JVM is running on IBM UNIX JVM
     * 
     */
    public static boolean isUnixIBM() {
        return IS_UNIX_IBM;
    }

    public static int javaVersion() {
        return JAVA_VERSION;
    }

    private static int javaVersion0() {
        try {
            // Check if its android, if so handle it the same way as java6.
            //
            // See https://github.com/netty/netty/issues/282
            Class.forName("android.app.Application");
            return 6;
        } catch (ClassNotFoundException e) {
            // Ignore
        }

        try {
            Class.forName("java.time.Clock", false, Object.class.getClassLoader());
            return 8;
        } catch (Exception e) {
            // Ignore
        }

        try {
            Class.forName(
                    "java.util.concurrent.LinkedTransferQueue", false,
                    BlockingQueue.class.getClassLoader());
            return 7;
        } catch (Exception e) {
            // Ignore
        }

        try {
            Class.forName(
                    "java.util.ArrayDeque", false, Queue.class.getClassLoader());
            return 6;
        } catch (Exception e) {
            // Ignore
        }

        return 5;
    }
}