//
//  ========================================================================
//  Copyright (c) 1995-2019 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;

ProcessorUtils provides access to runtime info about processors, that may be
overridden by system properties or environment variables.
This can be useful in virtualized environments where the runtime may miss
report the available resources.
/**
 * <p>ProcessorUtils provides access to runtime info about processors, that may be
 * overridden by system properties or environment variables.</p>
 * <p>This can be useful in virtualized environments where the runtime may miss
 * report the available resources.</p>
 */
public class ProcessorUtils
{
    public static final String AVAILABLE_PROCESSORS = "JETTY_AVAILABLE_PROCESSORS";
    private static int __availableProcessors = init();

    static int init()
    {
        String processors = System.getProperty(AVAILABLE_PROCESSORS, System.getenv(AVAILABLE_PROCESSORS));
        if (processors != null)
        {
            try
            {
                return Integer.parseInt(processors);
            }
            catch (NumberFormatException ignored)
            {
            }
        }
        return Runtime.getRuntime().availableProcessors();
    }

    
Returns the number of available processors, from System Property "JETTY_AVAILABLE_PROCESSORS", or if not set then from environment variable "JETTY_AVAILABLE_PROCESSORS" or if not set then from Runtime.availableProcessors(). 
Returns:
the number of processors/**
     * Returns the number of available processors, from System Property "JETTY_AVAILABLE_PROCESSORS",
     * or if not set then from environment variable "JETTY_AVAILABLE_PROCESSORS" or if not set then
     * from {@link Runtime#availableProcessors()}.
     *
     * @return the number of processors
     */
    public static int availableProcessors()
    {
        return __availableProcessors;
    }

    public static void setAvailableProcessors(int processors)
    {
        if (processors < 1)
            throw new IllegalArgumentException("Invalid number of processors: " + processors);
        __availableProcessors = processors;
    }
}