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/*
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  See the NOTICE file distributed with this work for additional
 *  information regarding copyright ownership.
 */

package org.seaborne.dboe.sys;

import java.nio.ByteOrder;
import java.util.concurrent.Executor ;
import java.util.concurrent.Executors ;

import org.apache.jena.atlas.logging.Log ;
import org.seaborne.dboe.DBOpEnvException ;
import org.slf4j.Logger ;
import org.slf4j.LoggerFactory ;

/** Low level environment */ 
public class Sys
{
    static final Logger log = LoggerFactory.getLogger("Sys") ;
    
    /** System log - use for general messages (a few) and warnings.
     *  Generally, do not log events unless you want every user to see them every time.
     *  Libraries and embedded systems should be seen and not heard.
     *  @see #errlog 
     */
    
    /** General system log */
    public static final Logger syslog = LoggerFactory.getLogger("System") ;
    /** Send warnings and error */
    public static final Logger errlog = LoggerFactory.getLogger("System") ;
    
    /** Size, in bytes, of a Java long */
    public static final int SizeOfLong              = Long.BYTES ; // Long.SIZE/Byte.SIZE ;
    
    /** Size, in bytes, of a Java int */
    public static final int SizeOfInt               = Integer.BYTES ; //Integer.SIZE/Byte.SIZE ;
    
    public static final boolean is64bitSystem = determineIf64Bit() ;
    
    public static final ByteOrder NetworkOrder      = ByteOrder.BIG_ENDIAN ;

    // To make the class initialize
    static public void init() {}

    public static void panic(Class clazz, String string) {
        Log.error(clazz, string) ;
        throw new DBOpEnvException(string) ;
    }
    public static final boolean isWindows = determineIfWindows() ;	// Memory mapped files behave differently.

    //Or look in File.listRoots.
    //Alternative method:
    //  http://stackoverflow.com/questions/1293533/name-of-the-operating-system-in-java-not-os-name
    
    private static boolean determineIfWindows() {
    	String s = System.getProperty("os.name") ;
    	if ( s == null )
    		return false ;
    	return s.startsWith("Windows ") ;
	}
    
    /** A general thread pool */
    public static Executor executor = Executors.newCachedThreadPool() ;

    private static boolean determineIf64Bit() {
        String s = System.getProperty("sun.arch.data.model") ;
        if ( s != null ) {
            boolean b = s.equals("64") ;
            syslog.debug("System architecture: " + (b ? "64 bit" : "32 bit")) ;
            return b ;
        }
        // Not a SUN VM
        s = System.getProperty("java.vm.info") ;
        if ( s == null ) {
            log.warn("Can't determine the data model") ;
            return false ;
        }
        log.debug("Can't determine the data model from 'sun.arch.data.model' - using java.vm.info") ;
        boolean b = s.contains("64") ;
        syslog.debug("System architecture: (from java.vm.info) " + (b ? "64 bit" : "32 bit")) ;
        return b ;
    }
}