MemoryUtils.java

//
//  ========================================================================
//  Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.util;

import java.security.AccessController;
import java.security.PrivilegedAction;

/**
 * MemoryUtils provides an abstraction over memory properties and operations.
 */
public class MemoryUtils
{
    private static final int cacheLineBytes;
    static
    {
        final int defaultValue = 64;
        int value = defaultValue;
        try
        {
            value = Integer.parseInt(AccessController.doPrivileged(new PrivilegedAction<String>()
            {
                @Override
                public String run()
                {
                    return System.getProperty("org.eclipse.jetty.util.cacheLineBytes", String.valueOf(defaultValue));
                }
            }));
        }
        catch (Exception ignored)
        {
        }
        cacheLineBytes = value;
    }

    private MemoryUtils()
    {
    }

    public static int getCacheLineBytes()
    {
        return cacheLineBytes;
    }

    public static int getIntegersPerCacheLine()
    {
        return getCacheLineBytes() >> 2;
    }

    public static int getLongsPerCacheLine()
    {
        return getCacheLineBytes() >> 3;
    }
}