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// ========================================================================
// Copyright (c) 2004-2009 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.log;

import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;

import org.eclipse.jetty.util.Loader;

/**
 * Logging.
 * This class provides a static logging interface.  If an instance of the
 * org.slf4j.Logger class is found on the classpath, the static log methods
 * are directed to a slf4j logger for "org.eclipse.log".   Otherwise the logs
 * are directed to stderr.
 * 

 * The "org.eclipse.jetty.util.log.class" system property can be used
 * to select a specific logging implementation.
 * 

 * If the system property org.eclipse.jetty.util.log.IGNORED is set,
 * then ignored exceptions are logged in detail.
 *
 * @see StdErrLog
 * @see Slf4jLog
 */
public class Log
{
    public final static String EXCEPTION= "EXCEPTION ";
    public final static String IGNORED= "IGNORED";

    public static String __logClass;
    public static boolean __ignored;

    static
    {
        AccessController.doPrivileged(new PrivilegedAction()
        {
            public Object run()
            {
                __logClass = System.getProperty("org.eclipse.jetty.util.log.class", "org.eclipse.jetty.util.log.Slf4jLog");
                __ignored = Boolean.parseBoolean(System.getProperty("org.eclipse.jetty.util.log.IGNORED", "false"));
                return null;
            }
        });
    }

    private static Logger __log;
    private static boolean __initialized;

    public static boolean initialized()
    {
        if (__log != null)
            return true;

        synchronized (Log.class)
        {
            if (__initialized)
                return __log != null;
            __initialized = true;
        }

        try
        {
            Class log_class = Loader.loadClass(Log.class, __logClass);
            if (__log == null || !__log.getClass().equals(log_class))
            {
                __log = (Logger)log_class.newInstance();
                __log.debug("Logging to {} via {}", __log, log_class.getName());
            }
        }
        catch(NoClassDefFoundError e)
        {
            initStandardLogging(e);
        }
        catch(Exception e)
        {
            initStandardLogging(e);
        }

        return __log != null;
    }

    private static void initStandardLogging(Throwable e)
    {
        Class log_class;
        if(e != null && __ignored)
            e.printStackTrace();
        if (__log == null)
        {
            log_class = StdErrLog.class;
            __log = new StdErrLog();
            __log.debug("Logging to {} via {}", __log, log_class.getName());
        }
    }

    public static void setLog(Logger log)
    {
        Log.__log = log;
    }

    public static Logger getLog()
    {
        initialized();
        return __log;
    }

    static boolean isIgnored()
    {
        return __ignored;
    }

    /**
     * Set Log to parent Logger.
     * 

     * If there is a different Log class available from a parent classloader,
     * call {@link #getLogger(String)} on it and construct a {@link LoggerLog} instance
     * as this Log's Logger, so that logging is delegated to the parent Log.
     * 

     * This should be used if a webapp is using Log, but wishes the logging to be
     * directed to the containers log.
     * 

     * If there is not parent Log, then this call is equivalent to
     *   Log.setLog(Log.getLogger(name));
     * 

     * @param name Logger name
     */
    public static void setLogToParent(String name)
    {
        ClassLoader loader = Log.class.getClassLoader();
        if (loader.getParent()!=null)
        {
            try
            {
                Class uberlog = loader.getParent().loadClass("org.eclipse.jetty.util.log.Log");
                Method getLogger = uberlog.getMethod("getLogger", new Class[]{String.class});
                Object logger = getLogger.invoke(null,name);
                setLog(new LoggerLog(logger));
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        }
        else
        {
            setLog(getLogger(name));
        }
    }

    public static void debug(Throwable th)
    {
        if (!isDebugEnabled())
            return;
        __log.debug(EXCEPTION, th);
    }

    public static void debug(String msg)
    {
        if (!initialized())
            return;
        __log.debug(msg);
    }

    public static void debug(String msg, Object arg)
    {
        if (!initialized())
            return;
        __log.debug(msg, arg);
    }

    public static void debug(String msg, Object arg0, Object arg1)
    {
        if (!initialized())
            return;
        __log.debug(msg, arg0, arg1);
    }

    /**
     * Ignore an exception unless trace is enabled.
     * This works around the problem that log4j does not support the trace level.
     * @param thrown the Throwable to ignore
     */
    public static void ignore(Throwable thrown)
    {
        if (!initialized())
            return;
        if (__ignored)
        {
            __log.warn(IGNORED, thrown);
        }
    }

    public static void info(String msg)
    {
        if (!initialized())
            return;
        __log.info(msg);
    }

    public static void info(String msg, Object arg)
    {
        if (!initialized())
            return;
        __log.info(msg, arg);
    }

    public static void info(String msg, Object arg0, Object arg1)
    {
        if (!initialized())
            return;
        __log.info(msg, arg0, arg1);
    }

    public static boolean isDebugEnabled()
    {
        if (!initialized())
            return false;
        return __log.isDebugEnabled();
    }

    public static void warn(String msg)
    {
        if (!initialized())
            return;
        __log.warn(msg);
    }

    public static void warn(String msg, Object arg)
    {
        if (!initialized())
            return;
        __log.warn(msg, arg);
    }

    public static void warn(String msg, Object arg0, Object arg1)
    {
        if (!initialized())
            return;
        __log.warn(msg, arg0, arg1);
    }

    public static void warn(String msg, Throwable th)
    {
        if (!initialized())
            return;
        __log.warn(msg, th);
    }

    public static void warn(Throwable th)
    {
        if (!initialized())
            return;
        __log.warn(EXCEPTION, th);
    }

    /**
     * Obtain a named Logger or the default Logger if null is passed.
     * @param name the Logger name
     * @return the Logger with the given name
     */
    public static Logger getLogger(String name)
    {
        if (!initialized())
            return null;

        return name == null ? __log : __log.getLogger(name);
    }
}
 















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