[jboss-cvs] apache/commons-logging/src/java/org/apache/commons/logging/impl ...

Scott Stark scott.stark at jboss.com
Fri Feb 9 01:57:15 EST 2007


  User: starksm 
  Date: 07/02/09 01:57:15

  Modified:    commons-logging/src/java/org/apache/commons/logging/impl           
                        package.html NoOpLog.java LogFactoryImpl.java
                        AvalonLogger.java SimpleLog.java
                        Jdk13LumberjackLogger.java Log4JLogger.java
                        Jdk14Logger.java LogKitLogger.java
  Added:       commons-logging/src/java/org/apache/commons/logging/impl           
                        WeakHashtable.java ServletContextCleaner.java
  Log:
  Update to the http://apache.ziply.com/jakarta/commons/logging/source/commons-logging-1.1-src.zip release
  
  Revision  Changes    Path
  1.2       +21 -21    apache/commons-logging/src/java/org/apache/commons/logging/impl/package.html
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: package.html
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/package.html,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  
  
  
  1.2       +106 -106  apache/commons-logging/src/java/org/apache/commons/logging/impl/NoOpLog.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: NoOpLog.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/NoOpLog.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- NoOpLog.java	17 Apr 2006 21:00:05 -0000	1.1
  +++ NoOpLog.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -28,7 +28,7 @@
    *
    * @author <a href="mailto:sanders at apache.org">Scott Sanders</a>
    * @author Rod Waldhoff
  - * @version $Id: NoOpLog.java,v 1.1 2006/04/17 21:00:05 starksm Exp $
  + * @version $Id: NoOpLog.java,v 1.2 2007/02/09 06:57:15 starksm Exp $
    */
   public class NoOpLog implements Log, Serializable {
   
  
  
  
  1.2       +1400 -549 apache/commons-logging/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: LogFactoryImpl.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- LogFactoryImpl.java	17 Apr 2006 21:00:05 -0000	1.1
  +++ LogFactoryImpl.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -20,8 +20,7 @@
   import java.lang.reflect.Constructor;
   import java.lang.reflect.InvocationTargetException;
   import java.lang.reflect.Method;
  -import java.security.AccessController;
  -import java.security.PrivilegedAction;
  +import java.net.URL;
   import java.util.Enumeration;
   import java.util.Hashtable;
   import java.util.Vector;
  @@ -57,25 +56,43 @@
    *
    * <p>This factory will remember previously created <code>Log</code> instances
    * for the same name, and will return them on repeated requests to the
  - * <code>getInstance()</code> method.  This implementation ignores any
  - * configured attributes.</p>
  + * <code>getInstance()</code> method.</p>
    *
    * @author Rod Waldhoff
    * @author Craig R. McClanahan
    * @author Richard A. Sitze
  - * @version $Revision: 1.1 $ $Date: 2006/04/17 21:00:05 $
  + * @author Brian Stansberry
  + * @version $Revision: 1.2 $ $Date: 2007/02/09 06:57:15 $
    */
   
   public class LogFactoryImpl extends LogFactory {
   
  +
  +    /** Log4JLogger class name */
  +    private static final String LOGGING_IMPL_LOG4J_LOGGER = "org.apache.commons.logging.impl.Log4JLogger";
  +    /** Jdk14Logger class name */
  +    private static final String LOGGING_IMPL_JDK14_LOGGER = "org.apache.commons.logging.impl.Jdk14Logger";
  +    /** Jdk13LumberjackLogger class name */
  +    private static final String LOGGING_IMPL_LUMBERJACK_LOGGER = "org.apache.commons.logging.impl.Jdk13LumberjackLogger";
  +    /** SimpleLog class name */
  +    private static final String LOGGING_IMPL_SIMPLE_LOGGER = "org.apache.commons.logging.impl.SimpleLog";
  +
  +    private static final String PKG_IMPL="org.apache.commons.logging.impl.";
  +    private static final int PKG_LEN = PKG_IMPL.length();
  +    
       // ----------------------------------------------------------- Constructors
   
   
  +
       /**
        * Public no-arguments constructor required by the lookup mechanism.
        */
       public LogFactoryImpl() {
           super();
  +        initDiagnostics();  // method on this object
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("Instance created.");
  +        }
       }
   
   
  @@ -83,8 +100,8 @@
   
   
       /**
  -     * The name of the system property identifying our {@link Log}
  -     * implementation class.
  +     * The name (<code>org.apache.commons.logging.Log</code>) of the system 
  +     * property identifying our {@link Log} implementation class.
        */
       public static final String LOG_PROPERTY =
           "org.apache.commons.logging.Log";
  @@ -92,21 +109,88 @@
   
       /**
        * The deprecated system property used for backwards compatibility with
  -     * the old {@link org.apache.commons.logging.LogSource} class.
  +     * old versions of JCL.
        */
       protected static final String LOG_PROPERTY_OLD =
           "org.apache.commons.logging.log";
   
  +    /**
  +     * The name (<code>org.apache.commons.logging.Log.allowFlawedContext</code>) 
  +     * of the system property which can be set true/false to
  +     * determine system behaviour when a bad context-classloader is encountered.
  +     * When set to false, a LogConfigurationException is thrown if
  +     * LogFactoryImpl is loaded via a child classloader of the TCCL (this
  +     * should never happen in sane systems).
  +     * 
  +     * Default behaviour: true (tolerates bad context classloaders)
  +     * 
  +     * See also method setAttribute.
  +     */
  +    public static final String ALLOW_FLAWED_CONTEXT_PROPERTY = 
  +        "org.apache.commons.logging.Log.allowFlawedContext";
  +
  +    /**
  +     * The name (<code>org.apache.commons.logging.Log.allowFlawedDiscovery</code>) 
  +     * of the system property which can be set true/false to
  +     * determine system behaviour when a bad logging adapter class is
  +     * encountered during logging discovery. When set to false, an
  +     * exception will be thrown and the app will fail to start. When set
  +     * to true, discovery will continue (though the user might end up
  +     * with a different logging implementation than they expected).
  +     * 
  +     * Default behaviour: true (tolerates bad logging adapters)
  +     * 
  +     * See also method setAttribute.
  +     */
  +    public static final String ALLOW_FLAWED_DISCOVERY_PROPERTY = 
  +        "org.apache.commons.logging.Log.allowFlawedDiscovery";
   
       /**
  -     * <p>The name of the {@link Log} interface class.</p>
  +     * The name (<code>org.apache.commons.logging.Log.allowFlawedHierarchy</code>) 
  +     * of the system property which can be set true/false to
  +     * determine system behaviour when a logging adapter class is
  +     * encountered which has bound to the wrong Log class implementation.
  +     * When set to false, an exception will be thrown and the app will fail
  +     * to start. When set to true, discovery will continue (though the user
  +     * might end up with a different logging implementation than they expected).
  +     * 
  +     * Default behaviour: true (tolerates bad Log class hierarchy)
  +     * 
  +     * See also method setAttribute.
        */
  -    private static final String LOG_INTERFACE =
  -        "org.apache.commons.logging.Log";
  +    public static final String ALLOW_FLAWED_HIERARCHY_PROPERTY = 
  +        "org.apache.commons.logging.Log.allowFlawedHierarchy";
  +
  +
  +    /**
  +     * The names of classes that will be tried (in order) as logging
  +     * adapters. Each class is expected to implement the Log interface,
  +     * and to throw NoClassDefFound or ExceptionInInitializerError when
  +     * loaded if the underlying logging library is not available. Any 
  +     * other error indicates that the underlying logging library is available
  +     * but broken/unusable for some reason.
  +     */
  +    private static final String[] classesToDiscover = {
  +            LOGGING_IMPL_LOG4J_LOGGER,
  +            "org.apache.commons.logging.impl.Jdk14Logger",
  +            "org.apache.commons.logging.impl.Jdk13LumberjackLogger",
  +            "org.apache.commons.logging.impl.SimpleLog"
  +    };
   
   
       // ----------------------------------------------------- Instance Variables
   
  +    /**
  +     * Determines whether logging classes should be loaded using the thread-context
  +     * classloader, or via the classloader that loaded this LogFactoryImpl class.
  +     */
  +    private boolean useTCCL = true;
  +
  +    /**
  +     * The string prefixed to every message output by the logDiagnostic method.
  +     */
  +    private String diagnosticPrefix;
  +
   
       /**
        * Configuration attributes.
  @@ -157,6 +241,20 @@
       protected Class logMethodSignature[] =
       { LogFactory.class };
   
  +    /**
  +     * See getBaseClassLoader and initConfiguration.
  +     */
  +    private boolean allowFlawedContext;
  +    
  +    /**
  +     * See handleFlawedDiscovery and initConfiguration.
  +     */
  +    private boolean allowFlawedDiscovery;
  +    
  +    /**
  +     * See handleFlawedHierarchy and initConfiguration.
  +     */
  +    private boolean allowFlawedHierarchy;
   
       // --------------------------------------------------------- Public Methods
   
  @@ -250,6 +348,7 @@
        */
       public void release() {
   
  +        logDiagnostic("Releasing all known loggers");
           instances.clear();
       }
   
  @@ -271,6 +370,21 @@
        * Set the configuration attribute with the specified name.  Calling
        * this with a <code>null</code> value is equivalent to calling
        * <code>removeAttribute(name)</code>.
  +     * <p>
  +     * This method can be used to set logging configuration programmatically
  +     * rather than via system properties. It can also be used in code running
  +     * within a container (such as a webapp) to configure behaviour on a
  +     * per-component level instead of globally as system properties would do.
  +     * To use this method instead of a system property, call
  +     * <pre>
  +     * LogFactory.getFactory().setAttribute(...)
  +     * </pre>
  +     * This must be done before the first Log object is created; configuration
  +     * changes after that point will be ignored.
  +     * <p>
  +     * This method is also called automatically if LogFactory detects a
  +     * commons-logging.properties file; every entry in that file is set
  +     * automatically as an attribute here.
        *
        * @param name Name of the attribute to set
        * @param value Value of the attribute to set, or <code>null</code>
  @@ -278,70 +392,126 @@
        */
       public void setAttribute(String name, Object value) {
   
  +        if (logConstructor != null) {
  +            logDiagnostic("setAttribute: call too late; configuration already performed.");
  +        }
  +
           if (value == null) {
               attributes.remove(name);
           } else {
               attributes.put(name, value);
           }
   
  +        if (name.equals(TCCL_KEY)) {
  +            useTCCL = Boolean.valueOf(value.toString()).booleanValue();
       }
   
  -
  -    // ------------------------------------------------------ Protected Methods
  +    }
   
   
  +    // ------------------------------------------------------ 
  +    // Static Methods
  +    //
  +    // These methods only defined as workarounds for a java 1.2 bug;
  +    // theoretically none of these are needed.
  +    // ------------------------------------------------------ 
   
       /**
  -     * Return the fully qualified Java classname of the {@link Log}
  -     * implementation we will be using.
  +     * Gets the context classloader.
  +     * This method is a workaround for a java 1.2 compiler bug.
  +     * @since 1.1
        */
  -    protected String getLogClassName() {
  -
  -        // Return the previously identified class name (if any)
  -        if (logClassName != null) {
  -            return logClassName;
  +    protected static ClassLoader getContextClassLoader() throws LogConfigurationException {
  +        return LogFactory.getContextClassLoader();
           }
   
  -        logClassName = (String) getAttribute(LOG_PROPERTY);
   
  -        if (logClassName == null) { // @deprecated
  -            logClassName = (String) getAttribute(LOG_PROPERTY_OLD);
  +    /**
  +     * Workaround for bug in Java1.2; in theory this method is not needed.
  +     * See LogFactory.isDiagnosticsEnabled.
  +     */
  +    protected static boolean isDiagnosticsEnabled() {
  +        return LogFactory.isDiagnosticsEnabled();
           }
   
  -        if (logClassName == null) {
  -            try {
  -                logClassName = System.getProperty(LOG_PROPERTY);
  -            } catch (SecurityException e) {
  -                ;
  -            }
  +    
  +    /**
  +     * Workaround for bug in Java1.2; in theory this method is not needed.
  +     * See LogFactory.getClassLoader.
  +     * @since 1.1
  +     */
  +    protected static ClassLoader getClassLoader(Class clazz) {
  +        return LogFactory.getClassLoader(clazz);
           }
   
  -        if (logClassName == null) { // @deprecated
  +
  +    // ------------------------------------------------------ Protected Methods
  +
  +    /**
  +     * Calculate and cache a string that uniquely identifies this instance,
  +     * including which classloader the object was loaded from.
  +     * <p>
  +     * This string will later be prefixed to each "internal logging" message
  +     * emitted, so that users can clearly see any unexpected behaviour.
  +     * <p>
  +     * Note that this method does not detect whether internal logging is 
  +     * enabled or not, nor where to output stuff if it is; that is all
  +     * handled by the parent LogFactory class. This method just computes
  +     * its own unique prefix for log messages.
  +     */
  +    private void initDiagnostics() {
  +        // It would be nice to include an identifier of the context classloader
  +        // that this LogFactoryImpl object is responsible for. However that
  +        // isn't possible as that information isn't available. It is possible
  +        // to figure this out by looking at the logging from LogFactory to
  +        // see the context & impl ids from when this object was instantiated,
  +        // in order to link the impl id output as this object's prefix back to
  +        // the context it is intended to manage.
  +        // Note that this prefix should be kept consistent with that 
  +        // in LogFactory.
  +        Class clazz = this.getClass();
  +        ClassLoader classLoader = getClassLoader(clazz);
  +        String classLoaderName;
               try {
  -                logClassName = System.getProperty(LOG_PROPERTY_OLD);
  -            } catch (SecurityException e) {
  -                ;
  +            if (classLoader == null) {
  +                classLoaderName = "BOOTLOADER";
  +            } else {
  +                classLoaderName = objectId(classLoader);
               }
  +        } catch(SecurityException e) {
  +            classLoaderName = "UNKNOWN";
           }
  -
  -        if ((logClassName == null) && isLog4JAvailable()) {
  -            logClassName = "org.apache.commons.logging.impl.Log4JLogger";
  +        diagnosticPrefix = "[LogFactoryImpl@" + System.identityHashCode(this) + " from " + classLoaderName + "] ";
           }
   
  -        if ((logClassName == null) && isJdk14Available()) {
  -            logClassName = "org.apache.commons.logging.impl.Jdk14Logger";
  -        }
   
  -        if ((logClassName == null) && isJdk13LumberjackAvailable()) {
  -            logClassName = "org.apache.commons.logging.impl.Jdk13LumberjackLogger";
  +    /**
  +     * Output a diagnostic message to a user-specified destination (if the
  +     * user has enabled diagnostic logging).
  +     * 
  +     * @param msg diagnostic message
  +     * @since 1.1
  +     */
  +    protected void logDiagnostic(String msg) {
  +        if (isDiagnosticsEnabled()) {
  +            logRawDiagnostic(diagnosticPrefix + msg);
  +        }
           }
   
  +    /**
  +     * Return the fully qualified Java classname of the {@link Log}
  +     * implementation we will be using.  
  +     * 
  +     * @deprecated  Never invoked by this class; subclasses should not assume
  +     *              it will be.
  +     */
  +    protected String getLogClassName() {
  +
           if (logClassName == null) {
  -            logClassName = "org.apache.commons.logging.impl.SimpleLog";
  +            discoverLogImplementation(getClass().getName());
           }
   
  -        return (logClassName);
  -
  +        return logClassName;
       }
   
   
  @@ -356,194 +526,875 @@
        *
        * @exception LogConfigurationException if a suitable constructor
        *  cannot be returned
  +     * 
  +     * @deprecated  Never invoked by this class; subclasses should not assume
  +     *              it will be.
        */
       protected Constructor getLogConstructor()
           throws LogConfigurationException {
   
           // Return the previously identified Constructor (if any)
  -        if (logConstructor != null) {
  +        if (logConstructor == null) {
  +            discoverLogImplementation(getClass().getName());
  +        }
  +
               return logConstructor;
           }
   
  -        String logClassName = getLogClassName();
   
  -        // Attempt to load the Log implementation class
  -        Class logClass = null;
  -        Class logInterface = null;
  -        try {
  -            logInterface = this.getClass().getClassLoader().loadClass
  -                (LOG_INTERFACE);
  -            logClass = loadClass(logClassName);
  -            if (logClass == null) {
  -                throw new LogConfigurationException
  -                    ("No suitable Log implementation for " + logClassName);
  +    /**
  +     * Is <em>JDK 1.3 with Lumberjack</em> logging available?   
  +     * 
  +     * @deprecated  Never invoked by this class; subclasses should not assume
  +     *              it will be.
  +     */
  +    protected boolean isJdk13LumberjackAvailable() {
  +        return isLogLibraryAvailable(
  +                "Jdk13Lumberjack",
  +                "org.apache.commons.logging.impl.Jdk13LumberjackLogger");
               }
  -            if (!logInterface.isAssignableFrom(logClass)) {
  -                Class interfaces[] = logClass.getInterfaces();
  -                for (int i = 0; i < interfaces.length; i++) {
  -                    if (LOG_INTERFACE.equals(interfaces[i].getName())) {
  -                        throw new LogConfigurationException
  -                            ("Invalid class loader hierarchy.  " +
  -                             "You have more than one version of '" +
  -                             LOG_INTERFACE + "' visible, which is " +
  -                             "not allowed.");
  +
  +
  +    /**
  +     * <p>Return <code>true</code> if <em>JDK 1.4 or later</em> logging
  +     * is available.  Also checks that the <code>Throwable</code> class
  +     * supports <code>getStackTrace()</code>, which is required by
  +     * Jdk14Logger.</p>  
  +     * 
  +     * @deprecated  Never invoked by this class; subclasses should not assume
  +     *              it will be.
  +     */
  +    protected boolean isJdk14Available() {
  +        return isLogLibraryAvailable(
  +                "Jdk14",
  +                "org.apache.commons.logging.impl.Jdk14Logger");
                       }
  +
  +
  +    /**
  +     * Is a <em>Log4J</em> implementation available? 
  +     * 
  +     * @deprecated  Never invoked by this class; subclasses should not assume
  +     *              it will be.
  +     */
  +    protected boolean isLog4JAvailable() {
  +        return isLogLibraryAvailable(
  +                "Log4J",
  +                LOGGING_IMPL_LOG4J_LOGGER);
                   }
  -                throw new LogConfigurationException
  -                    ("Class " + logClassName + " does not implement '" +
  -                     LOG_INTERFACE + "'.");
  +
  +
  +    /**
  +     * Create and return a new {@link org.apache.commons.logging.Log}
  +     * instance for the specified name.
  +     *
  +     * @param name Name of the new logger
  +     *
  +     * @exception LogConfigurationException if a new instance cannot
  +     *  be created
  +     */
  +    protected Log newInstance(String name) throws LogConfigurationException {
  +
  +        Log instance = null;
  +        try {
  +            if (logConstructor == null) {
  +                instance = discoverLogImplementation(name);
  +            }
  +            else {
  +                Object params[] = { name };
  +                instance = (Log) logConstructor.newInstance(params);
  +            }
  +            
  +            if (logMethod != null) {
  +                Object params[] = { this };
  +                logMethod.invoke(instance, params);
  +            }
  +            
  +            return (instance);
  +            
  +        } catch (LogConfigurationException lce) {
  +            
  +            // this type of exception means there was a problem in discovery
  +            // and we've already output diagnostics about the issue, etc.; 
  +            // just pass it on
  +            throw (LogConfigurationException) lce;
  +            
  +        } catch (InvocationTargetException e) {
  +            // A problem occurred invoking the Constructor or Method 
  +            // previously discovered
  +            Throwable c = e.getTargetException();
  +            if (c != null) {
  +                throw new LogConfigurationException(c);
  +            } else {
  +                throw new LogConfigurationException(e);
               }
           } catch (Throwable t) {
  +            // A problem occurred invoking the Constructor or Method 
  +            // previously discovered
               throw new LogConfigurationException(t);
           }
  +    }
   
  -        // Identify the <code>setLogFactory</code> method (if there is one)
  +
  +    //  ------------------------------------------------------ Private Methods
  +    
  +    /**
  +     * Utility method to check whether a particular logging library is
  +     * present and available for use. Note that this does <i>not</i>
  +     * affect the future behaviour of this class.
  +     */
  +    private boolean isLogLibraryAvailable(String name, String classname) {
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("Checking for '" + name + "'.");
  +        }
           try {
  -            logMethod = logClass.getMethod("setLogFactory",
  -                                           logMethodSignature);
  -        } catch (Throwable t) {
  -            logMethod = null;
  +            Log log = createLogFromClass(
  +                        classname, 
  +                        this.getClass().getName(), // dummy category
  +                        false);
  +
  +            if (log == null) {
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic("Did not find '" + name + "'.");
  +                }
  +                return false;
  +            } else {
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic("Found '" + name + "'.");
  +                }
  +                return true;
  +            }
  +        } catch(LogConfigurationException e) {
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("Logging system '" + name + "' is available but not useable.");
  +            }
  +            return false;
  +        }
  +    }
  +
  +    /**
  +     * Attempt to find an attribute (see method setAttribute) or a 
  +     * system property with the provided name and return its value.
  +     * <p>
  +     * The attributes associated with this object are checked before
  +     * system properties in case someone has explicitly called setAttribute,
  +     * or a configuration property has been set in a commons-logging.properties
  +     * file.
  +     * 
  +     * @return the value associated with the property, or null.
  +     */
  +    private String getConfigurationValue(String property) {
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("[ENV] Trying to get configuration for item " + property);
  +        }
  +
  +        Object valueObj =  getAttribute(property);
  +        if (valueObj != null) {
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("[ENV] Found LogFactory attribute [" + valueObj + "] for " + property);
  +            }
  +            return valueObj.toString();
  +        }
  +        
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("[ENV] No LogFactory attribute found for " + property);
           }
   
  -        // Identify the corresponding constructor to be used
           try {
  -            logConstructor = logClass.getConstructor(logConstructorSignature);
  -            return (logConstructor);
  -        } catch (Throwable t) {
  -            throw new LogConfigurationException
  -                ("No suitable Log constructor " +
  -                 logConstructorSignature+ " for " + logClassName, t);
  +            String value = System.getProperty(property);
  +            if (value != null) {
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic("[ENV] Found system property [" + value + "] for " + property);
  +                }
  +                return value;
           }
  +
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("[ENV] No system property found for property " + property);
  +            }
  +        } catch (SecurityException e) {
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("[ENV] Security prevented reading system property " + property);
  +            }
  +        }
  +
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("[ENV] No configuration defined for item " + property);
       }
   
  +        return null;
  +    }
   
       /**
  -     * MUST KEEP THIS METHOD PRIVATE.
  +     * Get the setting for the user-configurable behaviour specified by key.
  +     * If nothing has explicitly been set, then return dflt.  
  +     */
  +    private boolean getBooleanConfiguration(String key, boolean dflt) {
  +        String val = getConfigurationValue(key);
  +        if (val == null)
  +            return dflt;
  +        return Boolean.valueOf(val).booleanValue();
  +    }
  +
  +    /**
  +     * Initialize a number of variables that control the behaviour of this
  +     * class and that can be tweaked by the user. This is done when the first
  +     * logger is created, not in the constructor of this class, because we
  +     * need to give the user a chance to call method setAttribute in order to
  +     * configure this object.
  +     */
  +    private void initConfiguration() {
  +        allowFlawedContext = getBooleanConfiguration(ALLOW_FLAWED_CONTEXT_PROPERTY, true);
  +        allowFlawedDiscovery = getBooleanConfiguration(ALLOW_FLAWED_DISCOVERY_PROPERTY, true);
  +        allowFlawedHierarchy = getBooleanConfiguration(ALLOW_FLAWED_HIERARCHY_PROPERTY, true);
  +    }
  +  
  +
  +    /**
  +     * Attempts to create a Log instance for the given category name.
  +     * Follows the discovery process described in the class javadoc.
        *
  -     * <p>Exposing this method outside of
  -     * <code>org.apache.commons.logging.LogFactoryImpl</code>
  -     * will create a security violation:
  -     * This method uses <code>AccessController.doPrivileged()</code>.
  -     * </p>
  +     * @param logCategory the name of the log category
        *
  -     * Load a class, try first the thread class loader, and
  -     * if it fails use the loader that loaded this class.
  +     * @throws LogConfigurationException if an error in discovery occurs, 
  +     * or if no adapter at all can be instantiated
        */
  -    private static Class loadClass( final String name )
  -        throws ClassNotFoundException
  +    private Log discoverLogImplementation(String logCategory)
  +    throws LogConfigurationException
       {
  -        Object result = AccessController.doPrivileged(
  -            new PrivilegedAction() {
  -                public Object run() {
  -                    ClassLoader threadCL = getContextClassLoader();
  -                    if (threadCL != null) {
  -                        try {
  -                            return threadCL.loadClass(name);
  -                        } catch( ClassNotFoundException ex ) {
  -                            // ignore
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("Discovering a Log implementation...");
                           }
  +        
  +        initConfiguration();
  +        
  +        Log result = null;
  +        
  +        // See if the user specified the Log implementation to use
  +        String specifiedLogClassName = findUserSpecifiedLogClassName();
  +
  +        if (specifiedLogClassName != null) {
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("Attempting to load user-specified log class '" + 
  +                    specifiedLogClassName + "'...");
  +            }
  +            
  +            result = createLogFromClass(specifiedLogClassName,
  +                                        logCategory,
  +                                        true);
  +            if (result == null) {
  +                StringBuffer messageBuffer =  new StringBuffer("User-specified log class '");
  +                messageBuffer.append(specifiedLogClassName);
  +                messageBuffer.append("' cannot be found or is not useable.");
  +                
  +                // Mistyping or misspelling names is a common fault.
  +                // Construct a good error message, if we can
  +                if (specifiedLogClassName != null) {
  +                    informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_LOG4J_LOGGER);
  +                    informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_JDK14_LOGGER);
  +                    informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_LUMBERJACK_LOGGER);
  +                    informUponSimilarName(messageBuffer, specifiedLogClassName, LOGGING_IMPL_SIMPLE_LOGGER);
  +                }
  +                throw new LogConfigurationException(messageBuffer.toString());
  +            }
  +            
  +            return result;
  +        }
  +        
  +        // No user specified log; try to discover what's on the classpath
  +        //
  +        // Note that we deliberately loop here over classesToDiscover and
  +        // expect method createLogFromClass to loop over the possible source
  +        // classloaders. The effect is:
  +        //   for each discoverable log adapter
  +        //      for each possible classloader
  +        //          see if it works
  +        //
  +        // It appears reasonable at first glance to do the opposite: 
  +        //   for each possible classloader
  +        //     for each discoverable log adapter
  +        //        see if it works
  +        //
  +        // The latter certainly has advantages for user-installable logging
  +        // libraries such as log4j; in a webapp for example this code should
  +        // first check whether the user has provided any of the possible
  +        // logging libraries before looking in the parent classloader. 
  +        // Unfortunately, however, Jdk14Logger will always work in jvm>=1.4,
  +        // and SimpleLog will always work in any JVM. So the loop would never
  +        // ever look for logging libraries in the parent classpath. Yet many
  +        // users would expect that putting log4j there would cause it to be
  +        // detected (and this is the historical JCL behaviour). So we go with
  +        // the first approach. A user that has bundled a specific logging lib
  +        // in a webapp should use a commons-logging.properties file or a
  +        // service file in META-INF to force use of that logging lib anyway,
  +        // rather than relying on discovery.
  +        
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic(
  +                "No user-specified Log implementation; performing discovery" +
  +            	" using the standard supported logging implementations...");
                       }
  -                    try {
  -                        return Class.forName( name );
  -                    } catch (ClassNotFoundException e) {
  -                        return e;
  +        for(int i=0; (i<classesToDiscover.length) && (result == null); ++i) {
  +            result = createLogFromClass(classesToDiscover[i], logCategory, true);
                       }
  +        
  +        if (result == null) {
  +            throw new LogConfigurationException
  +                        ("No suitable Log implementation");
  +        }
  +        
  +        return result;        
                   }
  -            });
   
  -        if (result instanceof Class)
  -            return (Class)result;
   
  -        throw (ClassNotFoundException)result;
  +    /**
  +     * Appends message if the given name is similar to the candidate.
  +     * @param messageBuffer <code>StringBuffer</code> the message should be appended to, 
  +     * not null
  +     * @param name the (trimmed) name to be test against the candidate, not null
  +     * @param candidate the candidate name (not null)
  +     */
  +    private void informUponSimilarName(final StringBuffer messageBuffer, final String name, 
  +            final String candidate) {
  +        if (name.equals(candidate)) {
  +            // Don't suggest a name that is exactly the same as the one the
  +            // user tried...
  +            return;
  +        }
  +
  +        // If the user provides a name that is in the right package, and gets
  +        // the first 5 characters of the adapter class right (ignoring case),
  +        // then suggest the candidate adapter class name.
  +        if (name.regionMatches(true, 0, candidate, 0, PKG_LEN + 5)) {
  +            messageBuffer.append(" Did you mean '");
  +            messageBuffer.append(candidate);
  +            messageBuffer.append("'?");
  +        }
       }
   
   
       /**
  -     * Is <em>JDK 1.3 with Lumberjack</em> logging available?
  +     * Checks system properties and the attribute map for 
  +     * a Log implementation specified by the user under the 
  +     * property names {@link #LOG_PROPERTY} or {@link #LOG_PROPERTY_OLD}.
  +     * 
  +     * @return classname specified by the user, or <code>null</code>
        */
  -    protected boolean isJdk13LumberjackAvailable() {
  +    private String findUserSpecifiedLogClassName()
  +    {
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("Trying to get log class from attribute '" + LOG_PROPERTY + "'");
  +        }
  +        String specifiedClass = (String) getAttribute(LOG_PROPERTY);
   
  +        if (specifiedClass == null) { // @deprecated
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("Trying to get log class from attribute '" + 
  +                              LOG_PROPERTY_OLD + "'");
  +            }
  +            specifiedClass = (String) getAttribute(LOG_PROPERTY_OLD);
  +        }
  +
  +        if (specifiedClass == null) {
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("Trying to get log class from system property '" + 
  +                          LOG_PROPERTY + "'");
  +            }
           try {
  -            loadClass("java.util.logging.Logger");
  -            loadClass("org.apache.commons.logging.impl.Jdk13LumberjackLogger");
  -            return (true);
  -        } catch (Throwable t) {
  -            return (false);
  +                specifiedClass = System.getProperty(LOG_PROPERTY);
  +            } catch (SecurityException e) {
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic("No access allowed to system property '" + 
  +                        LOG_PROPERTY + "' - " + e.getMessage());
  +                }
  +            }
           }
   
  +        if (specifiedClass == null) { // @deprecated
  +            if (isDiagnosticsEnabled()) {
  +                logDiagnostic("Trying to get log class from system property '" + 
  +                          LOG_PROPERTY_OLD + "'");
  +            }
  +            try {
  +                specifiedClass = System.getProperty(LOG_PROPERTY_OLD);
  +            } catch (SecurityException e) {
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic("No access allowed to system property '" + 
  +                        LOG_PROPERTY_OLD + "' - " + e.getMessage());
  +                }
  +            }
  +        }
  +        
  +        // Remove any whitespace; it's never valid in a classname so its
  +        // presence just means a user mistake. As we know what they meant,
  +        // we may as well strip the spaces.
  +        if (specifiedClass != null) {
  +            specifiedClass = specifiedClass.trim();
  +        }
  +
  +        return specifiedClass;
       }
   
   
       /**
  -     * <p>Return <code>true</code> if <em>JDK 1.4 or later</em> logging
  -     * is available.  Also checks that the <code>Throwable</code> class
  -     * supports <code>getStackTrace()</code>, which is required by
  -     * Jdk14Logger.</p>
  -     */
  -    protected boolean isJdk14Available() {
  +     * Attempts to load the given class, find a suitable constructor,
  +     * and instantiate an instance of Log.
  +     * 
  +     * @param logAdapterClassName classname of the Log implementation
  +     * 
  +     * @param logCategory  argument to pass to the Log implementation's
  +     * constructor
  +     * 
  +     * @param affectState  <code>true</code> if this object's state should
  +     * be affected by this method call, <code>false</code> otherwise.
  +     * 
  +     * @return  an instance of the given class, or null if the logging
  +     * library associated with the specified adapter is not available.
  +     *                          
  +     * @throws LogConfigurationException if there was a serious error with
  +     * configuration and the handleFlawedDiscovery method decided this
  +     * problem was fatal.
  +     */                                  
  +    private Log createLogFromClass(String logAdapterClassName,
  +                                   String logCategory,
  +                                   boolean affectState) 
  +            throws LogConfigurationException {       
   
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("Attempting to instantiate '" + logAdapterClassName + "'");
  +        }
  +        
  +        Object[] params = { logCategory };
  +        Log logAdapter = null;
  +        Constructor constructor = null;
  +        
  +        Class logAdapterClass = null;
  +        ClassLoader currentCL = getBaseClassLoader();
  +        
  +        for(;;) {
  +            // Loop through the classloader hierarchy trying to find
  +            // a viable classloader.
  +            logDiagnostic(
  +                    "Trying to load '"
  +                    + logAdapterClassName
  +                    + "' from classloader "
  +                    + objectId(currentCL));
           try {
  -            loadClass("java.util.logging.Logger");
  -            loadClass("org.apache.commons.logging.impl.Jdk14Logger");
  -            Class throwable = loadClass("java.lang.Throwable");
  -            if (throwable.getDeclaredMethod("getStackTrace", null) == null) {
  -                return (false);
  +                if (isDiagnosticsEnabled()) {
  +                    // Show the location of the first occurrence of the .class file
  +                    // in the classpath. This is the location that ClassLoader.loadClass
  +                    // will load the class from -- unless the classloader is doing
  +                    // something weird. 
  +                    URL url;
  +                    String resourceName = logAdapterClassName.replace('.', '/') + ".class";
  +                    if (currentCL != null) {
  +                        url = currentCL.getResource(resourceName );
  +                    } else {
  +                        url = ClassLoader.getSystemResource(resourceName + ".class");
               }
  -            return (true);
  +
  +                    if (url == null) {
  +                        logDiagnostic("Class '" + logAdapterClassName + "' [" + resourceName + "] cannot be found.");
  +                    } else {
  +                        logDiagnostic("Class '" + logAdapterClassName + "' was found at '" + url + "'");
  +                    }
  +                }
  +
  +                Class c = null;
  +                try {
  +                    c = Class.forName(logAdapterClassName, true, currentCL);
  +                } catch (ClassNotFoundException originalClassNotFoundException) {
  +                    // The current classloader was unable to find the log adapter 
  +                    // in this or any ancestor classloader. There's no point in
  +                    // trying higher up in the hierarchy in this case..
  +                    String msg = "" + originalClassNotFoundException.getMessage();
  +                    logDiagnostic(
  +                        "The log adapter '"
  +                        + logAdapterClassName
  +                        + "' is not available via classloader " 
  +                        + objectId(currentCL)
  +                        + ": "
  +                        + msg.trim());
  +                    try {
  +                        // Try the class classloader.
  +                        // This may work in cases where the TCCL
  +                        // does not contain the code executed or JCL.
  +                        // This behaviour indicates that the application 
  +                        // classloading strategy is not consistent with the
  +                        // Java 1.2 classloading guidelines but JCL can
  +                        // and so should handle this case.
  +                        c = Class.forName(logAdapterClassName);
  +                    } catch (ClassNotFoundException secondaryClassNotFoundException) {
  +                        // no point continuing: this adapter isn't available
  +                        msg = "" + secondaryClassNotFoundException.getMessage();
  +                        logDiagnostic(
  +                            "The log adapter '"
  +                            + logAdapterClassName
  +                            + "' is not available via the LogFactoryImpl class classloader: "
  +                            + msg.trim());
  +                        break;
  +                    }
  +                }
  +                
  +                constructor = c.getConstructor(logConstructorSignature);
  +                Object o = constructor.newInstance(params);
  +
  +                // Note that we do this test after trying to create an instance
  +                // [rather than testing Log.class.isAssignableFrom(c)] so that
  +                // we don't complain about Log hierarchy problems when the
  +                // adapter couldn't be instantiated anyway.
  +                if (o instanceof Log) {
  +                    logAdapterClass = c;
  +                    logAdapter = (Log) o;
  +                    break;
  +                }
  +                
  +                // Oops, we have a potential problem here. An adapter class
  +                // has been found and its underlying lib is present too, but
  +                // there are multiple Log interface classes available making it
  +                // impossible to cast to the type the caller wanted. We 
  +                // certainly can't use this logger, but we need to know whether
  +                // to keep on discovering or terminate now.
  +                //
  +                // The handleFlawedHierarchy method will throw 
  +                // LogConfigurationException if it regards this problem as
  +                // fatal, and just return if not.
  +                handleFlawedHierarchy(currentCL, c);
  +            } catch (NoClassDefFoundError e) {
  +                // We were able to load the adapter but it had references to
  +                // other classes that could not be found. This simply means that
  +                // the underlying logger library is not present in this or any
  +                // ancestor classloader. There's no point in trying higher up
  +                // in the hierarchy in this case..
  +                String msg = "" + e.getMessage();
  +                logDiagnostic(
  +                    "The log adapter '"
  +                    + logAdapterClassName
  +                    + "' is missing dependencies when loaded via classloader "
  +                    + objectId(currentCL)
  +                    + ": "
  +                    + msg.trim());
  +                break;
  +            } catch (ExceptionInInitializerError e) {
  +                // A static initializer block or the initializer code associated 
  +                // with a static variable on the log adapter class has thrown
  +                // an exception.
  +                //
  +                // We treat this as meaning the adapter's underlying logging
  +                // library could not be found.
  +                String msg = "" + e.getMessage();
  +                logDiagnostic(
  +                    "The log adapter '"
  +                    + logAdapterClassName
  +                    + "' is unable to initialize itself when loaded via classloader "
  +                    + objectId(currentCL)
  +                    + ": "
  +                    + msg.trim());
  +                break;
  +            } catch(LogConfigurationException e) {
  +                // call to handleFlawedHierarchy above must have thrown
  +                // a LogConfigurationException, so just throw it on                
  +                throw e;
  +            } catch(Throwable t) {
  +                // handleFlawedDiscovery will determine whether this is a fatal
  +                // problem or not. If it is fatal, then a LogConfigurationException
  +                // will be thrown.
  +                handleFlawedDiscovery(logAdapterClassName, currentCL, t);
  +            }
  +                        
  +            if (currentCL == null) {
  +                break;
  +            }
  +            
  +            // try the parent classloader
  +            currentCL = currentCL.getParent();
  +        }
  +
  +        if ((logAdapter != null) && affectState) {
  +            // We've succeeded, so set instance fields
  +            this.logClassName   = logAdapterClassName;
  +            this.logConstructor = constructor;
  +            
  +            // Identify the <code>setLogFactory</code> method (if there is one)
  +            try {
  +                this.logMethod = logAdapterClass.getMethod("setLogFactory",
  +                                               logMethodSignature);
  +                logDiagnostic("Found method setLogFactory(LogFactory) in '" 
  +                              + logAdapterClassName + "'");
           } catch (Throwable t) {
  -            return (false);
  +                this.logMethod = null;
  +                logDiagnostic(
  +                    "[INFO] '" + logAdapterClassName 
  +                    + "' from classloader " + objectId(currentCL)
  +                    + " does not declare optional method "
  +                    + "setLogFactory(LogFactory)");
  +            }
  +            
  +            logDiagnostic(
  +                "Log adapter '" + logAdapterClassName 
  +                + "' from classloader " + objectId(logAdapterClass.getClassLoader())
  +                + " has been selected for use.");
  +        }
  +        
  +        return logAdapter;
           }
  +    
  +    
  +    /**
  +     * Return the classloader from which we should try to load the logging
  +     * adapter classes.
  +     * <p>
  +     * This method usually returns the context classloader. However if it
  +     * is discovered that the classloader which loaded this class is a child
  +     * of the context classloader <i>and</i> the allowFlawedContext option
  +     * has been set then the classloader which loaded this class is returned
  +     * instead.
  +     * <p>
  +     * The only time when the classloader which loaded this class is a
  +     * descendant (rather than the same as or an ancestor of the context
  +     * classloader) is when an app has created custom classloaders but
  +     * failed to correctly set the context classloader. This is a bug in
  +     * the calling application; however we provide the option for JCL to
  +     * simply generate a warning rather than fail outright.
  +     * 
  +     */
  +    private ClassLoader getBaseClassLoader() throws LogConfigurationException {
  +        ClassLoader thisClassLoader = getClassLoader(LogFactoryImpl.class);
  +        
  +        if (useTCCL == false) {
  +            return thisClassLoader;
       }
   
  +        ClassLoader contextClassLoader = getContextClassLoader();
  +
  +        ClassLoader baseClassLoader = getLowestClassLoader(
  +                contextClassLoader, thisClassLoader);
  +        
  +        if (baseClassLoader == null) {
  +           // The two classloaders are not part of a parent child relationship.
  +           // In some classloading setups (e.g. JBoss with its 
  +           // UnifiedLoaderRepository) this can still work, so if user hasn't
  +           // forbidden it, just return the contextClassLoader.
  +           if (allowFlawedContext) {   
  +              if (isDiagnosticsEnabled()) {
  +                   logDiagnostic(
  +                           "[WARNING] the context classloader is not part of a"
  +                           + " parent-child relationship with the classloader that"
  +                           + " loaded LogFactoryImpl.");
  +              }
  +              // If contextClassLoader were null, getLowestClassLoader() would
  +              // have returned thisClassLoader.  The fact we are here means
  +              // contextClassLoader is not null, so we can just return it.
  +              return contextClassLoader;
  +           }
  +           else {
  +            throw new LogConfigurationException(
  +                "Bad classloader hierarchy; LogFactoryImpl was loaded via"
  +                + " a classloader that is not related to the current context"
  +                + " classloader.");
  +           }           
  +        }
  +
  +        if (baseClassLoader != contextClassLoader) {
  +            // We really should just use the contextClassLoader as the starting
  +            // point for scanning for log adapter classes. However it is expected
  +            // that there are a number of broken systems out there which create
  +            // custom classloaders but fail to set the context classloader so
  +            // we handle those flawed systems anyway.
  +            if (allowFlawedContext) {
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic(
  +                            "Warning: the context classloader is an ancestor of the"
  +                            + " classloader that loaded LogFactoryImpl; it should be"
  +                            + " the same or a descendant. The application using"
  +                            + " commons-logging should ensure the context classloader"
  +                            + " is used correctly.");
  +                }
  +            } else {
  +                throw new LogConfigurationException(
  +                        "Bad classloader hierarchy; LogFactoryImpl was loaded via"
  +                        + " a classloader that is not related to the current context"
  +                        + " classloader."); 
  +            }
  +        }
  +        
  +        return baseClassLoader;
  +    }
   
       /**
  -     * Is a <em>Log4J</em> implementation available?
  +     * Given two related classloaders, return the one which is a child of
  +     * the other.
  +     * <p>
  +     * @param c1 is a classloader (including the null classloader)
  +     * @param c2 is a classloader (including the null classloader)
  +     * 
  +     * @return c1 if it has c2 as an ancestor, c2 if it has c1 as an ancestor,
  +     * and null if neither is an ancestor of the other.
        */
  -    protected boolean isLog4JAvailable() {
  +    private ClassLoader getLowestClassLoader(ClassLoader c1, ClassLoader c2) {
  +        // TODO: use AccessController when dealing with classloaders here
   
  -        try {
  -            loadClass("org.apache.log4j.Logger");
  -            loadClass("org.apache.commons.logging.impl.Log4JLogger");
  -            return (true);
  -        } catch (Throwable t) {
  -            return (false);
  +        if (c1 == null)
  +            return c2;
  +        
  +        if (c2 == null)
  +            return c1;
  +        
  +        ClassLoader current;
  +
  +        // scan c1's ancestors to find c2
  +        current = c1;
  +        while (current != null) {
  +            if (current == c2)
  +                return c1;
  +            current = current.getParent();
           }
  +       
  +        // scan c2's ancestors to find c1
  +        current = c2;
  +        while (current != null) {
  +            if (current == c1)
  +                return c2;
  +            current = current.getParent();
       }
   
  +        return null;
  +    }
   
       /**
  -     * Create and return a new {@link org.apache.commons.logging.Log}
  -     * instance for the specified name.
  +     * Generates an internal diagnostic logging of the discovery failure and 
  +     * then throws a <code>LogConfigurationException</code> that wraps 
  +     * the passed <code>Throwable</code>.
        *
  -     * @param name Name of the new logger
  +     * @param logAdapterClassName is the class name of the Log implementation
  +     * that could not be instantiated. Cannot be <code>null</code>.
        *
  -     * @exception LogConfigurationException if a new instance cannot
  -     *  be created
  +     * @param classLoader is the classloader that we were trying to load the
  +     * logAdapterClassName from when the exception occurred.
  +     * 
  +     * @param discoveryFlaw is the Throwable created by the classloader
  +     * 
  +     * @throws LogConfigurationException    ALWAYS
        */
  -    protected Log newInstance(String name) throws LogConfigurationException {
  +    private void handleFlawedDiscovery(String logAdapterClassName,
  +                                       ClassLoader classLoader,
  +                                       Throwable discoveryFlaw) {
   
  -        Log instance = null;
  -        try {
  -            Object params[] = new Object[1];
  -            params[0] = name;
  -            instance = (Log) getLogConstructor().newInstance(params);
  -            if (logMethod != null) {
  -                params[0] = this;
  -                logMethod.invoke(instance, params);
  +        if (isDiagnosticsEnabled()) {
  +            logDiagnostic("Could not instantiate Log '"
  +                      + logAdapterClassName + "' -- "
  +                      + discoveryFlaw.getClass().getName() + ": "
  +                      + discoveryFlaw.getLocalizedMessage());       
               }
  -            return (instance);
  -        } catch (InvocationTargetException e) {
  -            Throwable c = e.getTargetException();
  -            if (c != null) {
  -                throw new LogConfigurationException(c);
  -            } else {
  -                throw new LogConfigurationException(e);
  +        
  +        if (!allowFlawedDiscovery) {
  +            throw new LogConfigurationException(discoveryFlaw);
               }
  -        } catch (Throwable t) {
  -            throw new LogConfigurationException(t);
           }
   
  +    
  +    /**
  +     * Report a problem loading the log adapter, then either return 
  +     * (if the situation is considered recoverable) or throw a
  +     * LogConfigurationException.
  +     *  <p>
  +     * There are two possible reasons why we successfully loaded the 
  +     * specified log adapter class then failed to cast it to a Log object:
  +     * <ol>
  +     * <li>the specific class just doesn't implement the Log interface 
  +     *     (user screwed up), or
  +     * <li> the specified class has bound to a Log class loaded by some other
  +     *      classloader; Log at classloaderX cannot be cast to Log at classloaderY.
  +     * </ol>
  +     * <p>
  +     * Here we try to figure out which case has occurred so we can give the
  +     * user some reasonable feedback.
  +     * 
  +     * @param badClassLoader is the classloader we loaded the problem class from,
  +     * ie it is equivalent to badClass.getClassLoader().
  +     * 
  +     * @param badClass is a Class object with the desired name, but which 
  +     * does not implement Log correctly.
  +     * 
  +     * @throws LogConfigurationException when the situation
  +     * should not be recovered from.
  +     */
  +    private void handleFlawedHierarchy(ClassLoader badClassLoader, Class badClass)
  +    throws LogConfigurationException {
  +
  +        boolean implementsLog = false;
  +        String logInterfaceName = Log.class.getName();
  +        Class interfaces[] = badClass.getInterfaces();
  +        for (int i = 0; i < interfaces.length; i++) {
  +            if (logInterfaceName.equals(interfaces[i].getName())) {
  +                implementsLog = true;
  +                break;
  +            }
       }
   
  +        if (implementsLog) {
  +            // the class does implement an interface called Log, but
  +            // it is in the wrong classloader
  +            if (isDiagnosticsEnabled()) {
  +                try {
  +                    ClassLoader logInterfaceClassLoader = getClassLoader(Log.class);
  +                    logDiagnostic(
  +                        "Class '" + badClass.getName()
  +                        + "' was found in classloader " 
  +                        + objectId(badClassLoader)
  +                        + ". It is bound to a Log interface which is not"
  +                        + " the one loaded from classloader "
  +                        + objectId(logInterfaceClassLoader));
  +                } catch (Throwable t) {
  +                    logDiagnostic(
  +                        "Error while trying to output diagnostics about"
  +                        + " bad class '" + badClass + "'");
  +                }
  +            }
   
  +            if (!allowFlawedHierarchy) {
  +                StringBuffer msg = new StringBuffer();
  +                msg.append("Terminating logging for this context ");
  +                msg.append("due to bad log hierarchy. ");
  +                msg.append("You have more than one version of '");
  +                msg.append(Log.class.getName());
  +                msg.append("' visible.");
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic(msg.toString());
  +                } 
  +                throw new LogConfigurationException(msg.toString());
  +            }
  +        
  +            if (isDiagnosticsEnabled()) {
  +                StringBuffer msg = new StringBuffer();
  +                msg.append("Warning: bad log hierarchy. ");
  +                msg.append("You have more than one version of '");
  +                msg.append(Log.class.getName());
  +                msg.append("' visible.");
  +                logDiagnostic(msg.toString());
  +            }
  +        } else {
  +            // this is just a bad adapter class
  +            if (!allowFlawedDiscovery) {
  +                StringBuffer msg = new StringBuffer();
  +                msg.append("Terminating logging for this context. ");
  +                msg.append("Log class '");
  +                msg.append(badClass.getName());
  +                msg.append("' does not implement the Log interface.");
  +                if (isDiagnosticsEnabled()) {
  +                    logDiagnostic(msg.toString());
  +                }
  +                
  +                throw new LogConfigurationException(msg.toString());
  +            }
  +
  +            if (isDiagnosticsEnabled()) {
  +                StringBuffer msg = new StringBuffer();
  +                msg.append("[WARNING] Log class '");
  +                msg.append(badClass.getName());
  +                msg.append("' does not implement the Log interface.");
  +                logDiagnostic(msg.toString());
  +            }
  +        }
  +    }
   }
  
  
  
  1.2       +291 -223  apache/commons-logging/src/java/org/apache/commons/logging/impl/AvalonLogger.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: AvalonLogger.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/AvalonLogger.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- AvalonLogger.java	17 Apr 2006 21:00:04 -0000	1.1
  +++ AvalonLogger.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -1,5 +1,5 @@
   /*
  - * Copyright 2001-2004 The Apache Software Foundation.
  + * Copyright 2001-2004,2006 The Apache Software Foundation.
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
  @@ -16,7 +16,6 @@
   
   package org.apache.commons.logging.impl;
   
  -import java.io.Serializable;
   import org.apache.avalon.framework.logger.Logger;
   import org.apache.commons.logging.Log;
   
  @@ -39,18 +38,25 @@
    * to child loggers of this <code>Logger</code>.
    * </li>
    * </ul>
  - *
  + * <p>
  + * <strong>Note:</strong> <code>AvalonLogger</code> does not implement Serializable
  + * because the constructors available for it make this impossible to achieve in all
  + * circumstances; there is no way to "reconnect" to an underlying Logger object on
  + * deserialization if one was just passed in to the constructor of the original
  + * object. This class <i>was</i> marked Serializable in the 1.0.4 release of
  + * commons-logging, but this never actually worked (a NullPointerException would 
  + * be thrown as soon as the deserialized object was used), so removing this marker
  + * is not considered to be an incompatible change.
  + * </p>
    * @author <a href="mailto:neeme at apache.org">Neeme Praks</a>
  - * @version $Revision: 1.1 $ $Date: 2006/04/17 21:00:04 $
  + * @version $Revision: 1.2 $ $Date: 2007/02/09 06:57:15 $
    */
  -public class AvalonLogger implements Log, Serializable {
  +public class AvalonLogger implements Log {
   
       /** Ancesteral avalon logger  */ 
       private static Logger defaultLogger = null;
       /** Avalon logger used to perform log */
       private transient Logger logger = null;
  -    /** The name of this logger */
  -    private String name = null;
   
       /**
        * Constructs an <code>AvalonLogger</code> that outputs to the given
  @@ -58,7 +64,6 @@
        * @param logger the avalon logger implementation to delegate to
        */
       public AvalonLogger(Logger logger) {
  -        this.name = name;
           this.logger = logger;
       }
   
  @@ -70,7 +75,7 @@
       public AvalonLogger(String name) {
           if (defaultLogger == null)
               throw new NullPointerException("default logger has to be specified if this constructor is used!");
  -        this.logger = getLogger();
  +        this.logger = defaultLogger.getChildLogger(name);
       }
   
       /**
  @@ -78,9 +83,6 @@
        * @return avalon logger implementation
        */
       public Logger getLogger() {
  -        if (logger == null) {
  -            logger = defaultLogger.getChildLogger(name);
  -        }
           return logger;
       }
   
  @@ -95,62 +97,100 @@
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#debug(java.lang.Object, java.lang.Throwable)
  +    * Logs a message with
  +    * <code>org.apache.avalon.framework.logger.Logger.debug</code>.
  +    * 
  +    * @param message to log
  +    * @param t log this cause
  +    * @see org.apache.commons.logging.Log#debug(Object, Throwable)
        */
  -    public void debug(Object o, Throwable t) {
  -        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(o), t);
  +    public void debug(Object message, Throwable t) {
  +        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(message), t);
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#debug(java.lang.Object)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.debug</code>.
  +     * 
  +     * @param message to log.
  +     * @see org.apache.commons.logging.Log#debug(Object)
        */
  -    public void debug(Object o) {
  -        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(o));
  +    public void debug(Object message) {
  +        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(message));
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#error(java.lang.Object, java.lang.Throwable)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.error</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#error(Object, Throwable)
        */
  -    public void error(Object o, Throwable t) {
  -        if (getLogger().isErrorEnabled()) getLogger().error(String.valueOf(o), t);
  +    public void error(Object message, Throwable t) {
  +        if (getLogger().isErrorEnabled()) getLogger().error(String.valueOf(message), t);
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#error(java.lang.Object)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.error</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#error(Object)
        */
  -    public void error(Object o) {
  -        if (getLogger().isErrorEnabled()) getLogger().error(String.valueOf(o));
  +    public void error(Object message) {
  +        if (getLogger().isErrorEnabled()) getLogger().error(String.valueOf(message));
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#fatal(java.lang.Object, java.lang.Throwable)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.fatalError</code>.
  +     * 
  +     * @param message to log.
  +     * @param t log this cause.
  +     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
        */
  -    public void fatal(Object o, Throwable t) {
  -        if (getLogger().isFatalErrorEnabled()) getLogger().fatalError(String.valueOf(o), t);
  +    public void fatal(Object message, Throwable t) {
  +        if (getLogger().isFatalErrorEnabled()) getLogger().fatalError(String.valueOf(message), t);
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#fatal(java.lang.Object)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.fatalError</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#fatal(Object)
        */
  -    public void fatal(Object o) {
  -        if (getLogger().isFatalErrorEnabled()) getLogger().fatalError(String.valueOf(o));
  +    public void fatal(Object message) {
  +        if (getLogger().isFatalErrorEnabled()) getLogger().fatalError(String.valueOf(message));
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#info(java.lang.Object, java.lang.Throwable)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.info</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#info(Object, Throwable)
        */
  -    public void info(Object o, Throwable t) {
  -        if (getLogger().isInfoEnabled()) getLogger().info(String.valueOf(o), t);
  +    public void info(Object message, Throwable t) {
  +        if (getLogger().isInfoEnabled()) getLogger().info(String.valueOf(message), t);
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#info(java.lang.Object)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.info</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#info(Object)
        */
  -    public void info(Object o) {
  -        if (getLogger().isInfoEnabled()) getLogger().info(String.valueOf(o));
  +    public void info(Object message) {
  +        if (getLogger().isInfoEnabled()) getLogger().info(String.valueOf(message));
       }
   
       /**
  +     * Is logging to 
  +     * <code>org.apache.avalon.framework.logger.Logger.debug</code> enabled?
        * @see org.apache.commons.logging.Log#isDebugEnabled()
        */
       public boolean isDebugEnabled() {
  @@ -158,6 +198,8 @@
       }
   
       /**
  +     * Is logging to 
  +     * <code>org.apache.avalon.framework.logger.Logger.error</code> enabled?
        * @see org.apache.commons.logging.Log#isErrorEnabled()
        */
       public boolean isErrorEnabled() {
  @@ -165,6 +207,8 @@
       }
   
       /**
  +     * Is logging to 
  +     * <code>org.apache.avalon.framework.logger.Logger.fatalError</code> enabled?
        * @see org.apache.commons.logging.Log#isFatalEnabled()
        */
       public boolean isFatalEnabled() {
  @@ -172,6 +216,8 @@
       }
   
       /**
  +     * Is logging to
  +     * <code>org.apache.avalon.framework.logger.Logger.info</code> enabled?
        * @see org.apache.commons.logging.Log#isInfoEnabled()
        */
       public boolean isInfoEnabled() {
  @@ -179,6 +225,8 @@
       }
   
       /**
  +     * Is logging to 
  +     * <code>org.apache.avalon.framework.logger.Logger.debug</code> enabled?
        * @see org.apache.commons.logging.Log#isTraceEnabled()
        */
       public boolean isTraceEnabled() {
  @@ -186,6 +234,8 @@
       }
   
       /**
  +     * Is logging to 
  +     * <code>org.apache.avalon.framework.logger.Logger.warn</code> enabled?
        * @see org.apache.commons.logging.Log#isWarnEnabled()
        */
       public boolean isWarnEnabled() {
  @@ -193,31 +243,49 @@
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#trace(java.lang.Object, java.lang.Throwable)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.debug</code>.
  +     * 
  +     * @param message to log.
  +     * @param t log this cause.
  +     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
        */
  -    public void trace(Object o, Throwable t) {
  -        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(o), t);
  +    public void trace(Object message, Throwable t) {
  +        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(message), t);
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#trace(java.lang.Object)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.debug</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#trace(Object)
        */
  -    public void trace(Object o) {
  -        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(o));
  +    public void trace(Object message) {
  +        if (getLogger().isDebugEnabled()) getLogger().debug(String.valueOf(message));
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#warn(java.lang.Object, java.lang.Throwable)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.warn</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
        */
  -    public void warn(Object o, Throwable t) {
  -        if (getLogger().isWarnEnabled()) getLogger().warn(String.valueOf(o), t);
  +    public void warn(Object message, Throwable t) {
  +        if (getLogger().isWarnEnabled()) getLogger().warn(String.valueOf(message), t);
       }
   
       /**
  -     * @see org.apache.commons.logging.Log#warn(java.lang.Object)
  +     * Logs a message with
  +     * <code>org.apache.avalon.framework.logger.Logger.warn</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#warn(Object)
        */
  -    public void warn(Object o) {
  -        if (getLogger().isWarnEnabled()) getLogger().warn(String.valueOf(o));
  +    public void warn(Object message) {
  +        if (getLogger().isWarnEnabled()) getLogger().warn(String.valueOf(message));
       }
   
   }
  
  
  
  1.2       +708 -652  apache/commons-logging/src/java/org/apache/commons/logging/impl/SimpleLog.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: SimpleLog.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/SimpleLog.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- SimpleLog.java	17 Apr 2006 21:00:05 -0000	1.1
  +++ SimpleLog.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -70,7 +70,7 @@
    * @author Rod Waldhoff
    * @author Robert Burrell Donkin
    *
  - * @version $Id: SimpleLog.java,v 1.1 2006/04/17 21:00:05 starksm Exp $
  + * @version $Id: SimpleLog.java,v 1.2 2007/02/09 06:57:15 starksm Exp $
    */
   public class SimpleLog implements Log, Serializable {
   
  @@ -360,7 +360,11 @@
   
   
       /**
  -     * <p> Log a message with debug log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_DEBUG</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#debug(Object)
        */
       public final void debug(Object message) {
   
  @@ -371,7 +375,12 @@
   
   
       /**
  -     * <p> Log an error with debug log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_DEBUG</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
        */
       public final void debug(Object message, Throwable t) {
   
  @@ -382,7 +391,11 @@
   
   
       /**
  -     * <p> Log a message with trace log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_TRACE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#trace(Object)
        */
       public final void trace(Object message) {
   
  @@ -393,7 +406,12 @@
   
   
       /**
  -     * <p> Log an error with trace log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_TRACE</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
        */
       public final void trace(Object message, Throwable t) {
   
  @@ -404,7 +422,11 @@
   
   
       /**
  -     * <p> Log a message with info log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_INFO</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#info(Object)
        */
       public final void info(Object message) {
   
  @@ -415,7 +437,12 @@
   
   
       /**
  -     * <p> Log an error with info log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_INFO</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#info(Object, Throwable)
        */
       public final void info(Object message, Throwable t) {
   
  @@ -426,7 +453,11 @@
   
   
       /**
  -     * <p> Log a message with warn log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_WARN</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#warn(Object)
        */
       public final void warn(Object message) {
   
  @@ -437,7 +468,12 @@
   
   
       /**
  -     * <p> Log an error with warn log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_WARN</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
        */
       public final void warn(Object message, Throwable t) {
   
  @@ -448,7 +484,11 @@
   
   
       /**
  -     * <p> Log a message with error log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_ERROR</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#error(Object)
        */
       public final void error(Object message) {
   
  @@ -459,7 +499,12 @@
   
   
       /**
  -     * <p> Log an error with error log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_ERROR</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#error(Object, Throwable)
        */
       public final void error(Object message, Throwable t) {
   
  @@ -470,7 +515,11 @@
   
   
       /**
  -     * <p> Log a message with fatal log level.</p>
  +     * Log a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_FATAL</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#fatal(Object)
        */
       public final void fatal(Object message) {
   
  @@ -481,7 +530,12 @@
   
   
       /**
  -     * <p> Log an error with fatal log level.</p>
  +     * Logs a message with 
  +     * <code>org.apache.commons.logging.impl.SimpleLog.LOG_LEVEL_FATAL</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
        */
       public final void fatal(Object message, Throwable t) {
   
  @@ -586,11 +640,13 @@
           if (classLoader == null) {
               try {
                   // Are we running on a JDK 1.2 or later system?
  -                Method method = Thread.class.getMethod("getContextClassLoader", null);
  +                Method method = Thread.class.getMethod("getContextClassLoader",
  +                        (Class[]) null);
   
                   // Get the thread context class loader (if there is one)
                   try {
  -                    classLoader = (ClassLoader)method.invoke(Thread.currentThread(), null);
  +                    classLoader = (ClassLoader)method.invoke(Thread.currentThread(), 
  +                            (Class[]) null);
                   } catch (IllegalAccessException e) {
                       ;  // ignore
                   } catch (InvocationTargetException e) {
  
  
  
  1.2       +78 -27    apache/commons-logging/src/java/org/apache/commons/logging/impl/Jdk13LumberjackLogger.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: Jdk13LumberjackLogger.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/Jdk13LumberjackLogger.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- Jdk13LumberjackLogger.java	17 Apr 2006 21:00:05 -0000	1.1
  +++ Jdk13LumberjackLogger.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -38,7 +38,8 @@
    * @author <a href="mailto:bloritsch at apache.org">Berin Loritsch</a>
    * @author <a href="mailto:donaldp at apache.org">Peter Donald</a>
    * @author <a href="mailto:vince256 at comcast.net">Vince Eagen</a>
  - * @version $Revision: 1.1 $ $Date: 2006/04/17 21:00:05 $
  + * @version $Revision: 1.2 $ $Date: 2007/02/09 06:57:15 $
  + * @since 1.1
    */
   
   public class Jdk13LumberjackLogger implements Log, Serializable {
  @@ -57,6 +58,14 @@
       private boolean classAndMethodFound = false;
   
   
  +    /**
  +     * This member variable simply ensures that any attempt to initialise
  +     * this class in a pre-1.4 JVM will result in an ExceptionInInitializerError.
  +     * It must not be private, as an optimising compiler could detect that it
  +     * is not used and optimise it away.
  +     */
  +    protected static final Level dummyLevel = Level.FINE;
  +
       // ----------------------------------------------------------- Constructors
   
   
  @@ -126,7 +135,10 @@
       }
   
       /**
  -     * Log a message with debug log level.
  +     * Logs a message with <code>java.util.logging.Level.FINE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#debug(Object)
        */
       public void debug(Object message) {
           log(Level.FINE, String.valueOf(message), null);
  @@ -134,7 +146,11 @@
   
   
       /**
  -     * Log a message and exception with debug log level.
  +     * Logs a message with <code>java.util.logging.Level.FINE</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
        */
       public void debug(Object message, Throwable exception) {
           log(Level.FINE, String.valueOf(message), exception);
  @@ -142,7 +158,10 @@
   
   
       /**
  -     * Log a message with error log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#error(Object)
        */
       public void error(Object message) {
           log(Level.SEVERE, String.valueOf(message), null);
  @@ -150,7 +169,11 @@
   
   
       /**
  -     * Log a message and exception with error log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#error(Object, Throwable)
        */
       public void error(Object message, Throwable exception) {
           log(Level.SEVERE, String.valueOf(message), exception);
  @@ -158,7 +181,10 @@
   
   
       /**
  -     * Log a message with fatal log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#fatal(Object)
        */
       public void fatal(Object message) {
           log(Level.SEVERE, String.valueOf(message), null);
  @@ -166,7 +192,11 @@
   
   
       /**
  -     * Log a message and exception with fatal log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
        */
       public void fatal(Object message, Throwable exception) {
           log(Level.SEVERE, String.valueOf(message), exception);
  @@ -185,7 +215,10 @@
   
   
       /**
  -     * Log a message with info log level.
  +     * Logs a message with <code>java.util.logging.Level.INFO</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#info(Object)
        */
       public void info(Object message) {
           log(Level.INFO, String.valueOf(message), null);
  @@ -193,7 +226,11 @@
   
   
       /**
  -     * Log a message and exception with info log level.
  +     * Logs a message with <code>java.util.logging.Level.INFO</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#info(Object, Throwable)
        */
       public void info(Object message, Throwable exception) {
           log(Level.INFO, String.valueOf(message), exception);
  @@ -249,7 +286,10 @@
   
   
       /**
  -     * Log a message with trace log level.
  +     * Logs a message with <code>java.util.logging.Level.FINEST</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#trace(Object)
        */
       public void trace(Object message) {
           log(Level.FINEST, String.valueOf(message), null);
  @@ -257,7 +297,11 @@
   
   
       /**
  -     * Log a message and exception with trace log level.
  +     * Logs a message with <code>java.util.logging.Level.FINEST</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
        */
       public void trace(Object message, Throwable exception) {
           log(Level.FINEST, String.valueOf(message), exception);
  @@ -265,7 +309,10 @@
   
   
       /**
  -     * Log a message with warn log level.
  +     * Logs a message with <code>java.util.logging.Level.WARNING</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#warn(Object)
        */
       public void warn(Object message) {
           log(Level.WARNING, String.valueOf(message), null);
  @@ -273,7 +320,11 @@
   
   
       /**
  -     * Log a message and exception with warn log level.
  +     * Logs a message with <code>java.util.logging.Level.WARNING</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
        */
       public void warn(Object message, Throwable exception) {
           log(Level.WARNING, String.valueOf(message), exception);
  
  
  
  1.3       +312 -108  apache/commons-logging/src/java/org/apache/commons/logging/impl/Log4JLogger.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: Log4JLogger.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/Log4JLogger.java,v
  retrieving revision 1.2
  retrieving revision 1.3
  diff -u -b -r1.2 -r1.3
  --- Log4JLogger.java	19 Apr 2006 02:38:59 -0000	1.2
  +++ Log4JLogger.java	9 Feb 2007 06:57:15 -0000	1.3
  @@ -13,120 +13,324 @@
    * See the License for the specific language governing permissions and
    * limitations under the License.
    */
  +
  +
   package org.apache.commons.logging.impl;
   
   import java.io.Serializable;
  -
   import org.apache.commons.logging.Log;
  +import org.apache.log4j.Logger;
  +import org.apache.log4j.Priority;
  +import org.apache.log4j.Level;
   
   /**
  - * Implementation of Log that reflectively maps to a log4j
  + * Implementation of {@link Log} that maps directly to a
  + * <strong>Logger</strong> for log4J version 1.2.
  + * <p>
  + * Initial configuration of the corresponding Logger instances should be done
  + * in the usual manner, as outlined in the Log4J documentation.
  + * <p>
  + * The reason this logger is distinct from the 1.3 logger is that in version 1.2
  + * of Log4J:
  + * <ul>
  + * <li>class Logger takes Priority parameters not Level parameters.
  + * <li>class Level extends Priority
  + * </ul>
  + * Log4J1.3 is expected to change Level so it no longer extends Priority, which is
  + * a non-binary-compatible change. The class generated by compiling this code against
  + * log4j 1.2 will therefore not run against log4j 1.3.
    *
  - * @author Scott.Stark at jboss.org
  - * @version $Revision: 1.2 $
  + * @author <a href="mailto:sanders at apache.org">Scott Sanders</a>
  + * @author Rod Waldhoff
  + * @author Robert Burrell Donkin
  + * @version $Id: Log4JLogger.java,v 1.3 2007/02/09 06:57:15 starksm Exp $
    */
  -public class Log4JLogger implements Log, Serializable
  -{
  -   private static final long serialVersionUID = 1;
  -   private Log theLogger;
   
  -   public Log4JLogger()
  -   {
  +public class Log4JLogger implements Log, Serializable {
  +
  +    // ------------------------------------------------------------- Attributes
  +
  +    /** The fully qualified name of the Log4JLogger class. */
  +    private static final String FQCN = Log4JLogger.class.getName();
  +    
  +    /** Log to this logger */
  +    private transient Logger logger = null;
  +
  +    /** Logger name */
  +    private String name = null;
  +
  +    private static Priority traceLevel;
  +    
  +    // ------------------------------------------------------------
  +    // Static Initializer.
  +    //
  +    // Note that this must come after the static variable declarations
  +    // otherwise initialiser expressions associated with those variables
  +    // will override any settings done here.
  +    //
  +    // Verify that log4j is available, and that it is version 1.2.
  +    // If an ExceptionInInitializerError is generated, then LogFactoryImpl
  +    // will treat that as meaning that the appropriate underlying logging
  +    // library is just not present - if discovery is in progress then
  +    // discovery will continue.
  +    // ------------------------------------------------------------
  +
  +    static {
  +        if (!Priority.class.isAssignableFrom(Level.class)) {
  +            // nope, this is log4j 1.3, so force an ExceptionInInitializerError
  +            throw new InstantiationError("Log4J 1.2 not available");
      }
   
  -   public Log4JLogger(String name)
  -   {
  -      this.theLogger = new Log4jProxy(name);
  +        // Releases of log4j1.2 >= 1.2.12 have Priority.TRACE available, earlier
  +        // versions do not. If TRACE is not available, then we have to map
  +        // calls to Log.trace(...) onto the DEBUG level.
  +        
  +        try {
  +            traceLevel = (Priority) Level.class.getDeclaredField("TRACE").get(null);
  +        } catch(Exception ex) {
  +            // ok, trace not available
  +            traceLevel = Priority.DEBUG;
  +        }
      }
   
  -   public boolean isDebugEnabled()
  -   {
  -      return theLogger.isDebugEnabled();
  +    
  +    // ------------------------------------------------------------ Constructor
  +
  +    public Log4JLogger() {
      }
   
  -   public boolean isErrorEnabled()
  -   {
  -      return theLogger.isErrorEnabled();
  +
  +    /**
  +     * Base constructor.
  +     */
  +    public Log4JLogger(String name) {
  +        this.name = name;
  +        this.logger = getLogger();
      }
   
  -   public boolean isFatalEnabled()
  -   {
  -      return theLogger.isFatalEnabled();
  +    /** For use with a log4j factory.
  +     */
  +    public Log4JLogger(Logger logger ) {
  +        this.name = logger.getName();
  +        this.logger=logger;
      }
   
  -   public boolean isInfoEnabled()
  -   {
  -      return theLogger.isInfoEnabled();
  +
  +    // --------------------------------------------------------- 
  +    // Implementation
  +    //
  +    // Note that in the methods below the Priority class is used to define
  +    // levels even though the Level class is supported in 1.2. This is done
  +    // so that at compile time the call definitely resolves to a call to
  +    // a method that takes a Priority rather than one that takes a Level.
  +    // 
  +    // The Category class (and hence its subclass Logger) in version 1.2 only
  +    // has methods that take Priority objects. The Category class (and hence
  +    // Logger class) in version 1.3 has methods that take both Priority and
  +    // Level objects. This means that if we use Level here, and compile
  +    // against log4j 1.3 then calls would be bound to the versions of
  +    // methods taking Level objects and then would fail to run against
  +    // version 1.2 of log4j.
  +    // --------------------------------------------------------- 
  +
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
  +     * When using a log4j version that does not support the <code>TRACE</code>
  +     * level, the message will be logged at the <code>DEBUG</code> level.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#trace(Object)
  +     */
  +    public void trace(Object message) {
  +        getLogger().log(FQCN, traceLevel, message, null );
      }
   
  -   public boolean isTraceEnabled()
  -   {
  -      return theLogger.isTraceEnabled();
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.TRACE</code>.
  +     * When using a log4j version that does not support the <code>TRACE</code>
  +     * level, the message will be logged at the <code>DEBUG</code> level.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
  +     */
  +    public void trace(Object message, Throwable t) {
  +        getLogger().log(FQCN, traceLevel, message, t );
      }
   
  -   public boolean isWarnEnabled()
  -   {
  -      return theLogger.isWarnEnabled();
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#debug(Object)
  +     */
  +    public void debug(Object message) {
  +        getLogger().log(FQCN, Priority.DEBUG, message, null );
      }
   
  -   public void trace(Object message)
  -   {
  -      theLogger.trace(message);
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.DEBUG</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
  +     */
  +    public void debug(Object message, Throwable t) {
  +        getLogger().log(FQCN, Priority.DEBUG, message, t );
      }
   
  -   public void trace(Object message, Throwable t)
  -   {
  -      theLogger.trace(message, t);
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#info(Object)
  +     */
  +    public void info(Object message) {
  +        getLogger().log(FQCN, Priority.INFO, message, null );
      }
   
  -   public void debug(Object message)
  -   {
  -      theLogger.debug(message);
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.INFO</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#info(Object, Throwable)
  +     */
  +    public void info(Object message, Throwable t) {
  +        getLogger().log(FQCN, Priority.INFO, message, t );
      }
   
  -   public void debug(Object message, Throwable t)
  -   {
  -      theLogger.debug(message, t);
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#warn(Object)
  +     */
  +    public void warn(Object message) {
  +        getLogger().log(FQCN, Priority.WARN, message, null );
      }
   
  -   public void info(Object message)
  -   {
  -      theLogger.info(message);
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.WARN</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
  +     */
  +    public void warn(Object message, Throwable t) {
  +        getLogger().log(FQCN, Priority.WARN, message, t );
  +    }
  +
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#error(Object)
  +     */
  +    public void error(Object message) {
  +        getLogger().log(FQCN, Priority.ERROR, message, null );
  +    }
  +
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.ERROR</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#error(Object, Throwable)
  +     */
  +    public void error(Object message, Throwable t) {
  +        getLogger().log(FQCN, Priority.ERROR, message, t );
  +    }
  +
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#fatal(Object)
  +     */
  +    public void fatal(Object message) {
  +        getLogger().log(FQCN, Priority.FATAL, message, null );
      }
   
  -   public void info(Object message, Throwable t)
  -   {
  -      theLogger.info(message, t);
  +
  +    /**
  +     * Logs a message with <code>org.apache.log4j.Priority.FATAL</code>.
  +     *
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
  +     */
  +    public void fatal(Object message, Throwable t) {
  +        getLogger().log(FQCN, Priority.FATAL, message, t );
      }
   
  -   public void warn(Object message)
  -   {
  -      theLogger.warn(message);
  +
  +    /**
  +     * Return the native Logger instance we are using.
  +     */
  +    public Logger getLogger() {
  +        if (logger == null) {
  +            logger = Logger.getLogger(name);
      }
  +        return (this.logger);
  +    }
  +
   
  -   public void warn(Object message, Throwable t)
  -   {
  -      theLogger.warn(message, t);
  +    /**
  +     * Check whether the Log4j Logger used is enabled for <code>DEBUG</code> priority.
  +     */
  +    public boolean isDebugEnabled() {
  +        return getLogger().isDebugEnabled();
      }
   
  -   public void error(Object message)
  -   {
  -      theLogger.error(message);
  +
  +     /**
  +     * Check whether the Log4j Logger used is enabled for <code>ERROR</code> priority.
  +     */
  +    public boolean isErrorEnabled() {
  +        return getLogger().isEnabledFor(Priority.ERROR);
      }
   
  -   public void error(Object message, Throwable t)
  -   {
  -      theLogger.error(message, t);
  +
  +    /**
  +     * Check whether the Log4j Logger used is enabled for <code>FATAL</code> priority.
  +     */
  +    public boolean isFatalEnabled() {
  +        return getLogger().isEnabledFor(Priority.FATAL);
      }
   
  -   public void fatal(Object message)
  -   {
  -      theLogger.fatal(message);
  +
  +    /**
  +     * Check whether the Log4j Logger used is enabled for <code>INFO</code> priority.
  +     */
  +    public boolean isInfoEnabled() {
  +        return getLogger().isInfoEnabled();
      }
   
  -   public void fatal(Object message, Throwable t)
  -   {
  -      theLogger.fatal(message, t);
  +
  +    /**
  +     * Check whether the Log4j Logger used is enabled for <code>TRACE</code> priority.
  +     * When using a log4j version that does not support the TRACE level, this call
  +     * will report whether <code>DEBUG</code> is enabled or not.
  +     */
  +    public boolean isTraceEnabled() {
  +        return getLogger().isEnabledFor(traceLevel);
      }
   
  +    /**
  +     * Check whether the Log4j Logger used is enabled for <code>WARN</code> priority.
  +     */
  +    public boolean isWarnEnabled() {
  +        return getLogger().isEnabledFor(Priority.WARN);
  +    }
   }
  
  
  
  1.2       +303 -254  apache/commons-logging/src/java/org/apache/commons/logging/impl/Jdk14Logger.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: Jdk14Logger.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/Jdk14Logger.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- Jdk14Logger.java	17 Apr 2006 21:00:05 -0000	1.1
  +++ Jdk14Logger.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -33,11 +33,18 @@
    * @author <a href="mailto:sanders at apache.org">Scott Sanders</a>
    * @author <a href="mailto:bloritsch at apache.org">Berin Loritsch</a>
    * @author <a href="mailto:donaldp at apache.org">Peter Donald</a>
  - * @version $Revision: 1.1 $ $Date: 2006/04/17 21:00:05 $
  + * @version $Revision: 1.2 $ $Date: 2007/02/09 06:57:15 $
    */
   
   public class Jdk14Logger implements Log, Serializable {
   
  +    /**
  +     * This member variable simply ensures that any attempt to initialise
  +     * this class in a pre-1.4 JVM will result in an ExceptionInInitializerError.
  +     * It must not be private, as an optimising compiler could detect that it
  +     * is not used and optimise it away.
  +     */
  +    protected static final Level dummyLevel = Level.FINE;
   
       // ----------------------------------------------------------- Constructors
   
  @@ -97,7 +104,10 @@
       }
   
       /**
  -     * Log a message with debug log level.
  +     * Logs a message with <code>java.util.logging.Level.FINE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#debug(Object)
        */
       public void debug(Object message) {
           log(Level.FINE, String.valueOf(message), null);
  @@ -105,7 +115,11 @@
   
   
       /**
  -     * Log a message and exception with debug log level.
  +     * Logs a message with <code>java.util.logging.Level.FINE</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
        */
       public void debug(Object message, Throwable exception) {
           log(Level.FINE, String.valueOf(message), exception);
  @@ -113,7 +127,10 @@
   
   
       /**
  -     * Log a message with error log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#error(Object)
        */
       public void error(Object message) {
           log(Level.SEVERE, String.valueOf(message), null);
  @@ -121,7 +138,11 @@
   
   
       /**
  -     * Log a message and exception with error log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#error(Object, Throwable)
        */
       public void error(Object message, Throwable exception) {
           log(Level.SEVERE, String.valueOf(message), exception);
  @@ -129,7 +150,10 @@
   
   
       /**
  -     * Log a message with fatal log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#fatal(Object)
        */
       public void fatal(Object message) {
           log(Level.SEVERE, String.valueOf(message), null);
  @@ -137,7 +161,11 @@
   
   
       /**
  -     * Log a message and exception with fatal log level.
  +     * Logs a message with <code>java.util.logging.Level.SEVERE</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
        */
       public void fatal(Object message, Throwable exception) {
           log(Level.SEVERE, String.valueOf(message), exception);
  @@ -156,7 +184,10 @@
   
   
       /**
  -     * Log a message with info log level.
  +     * Logs a message with <code>java.util.logging.Level.INFO</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#info(Object)
        */
       public void info(Object message) {
           log(Level.INFO, String.valueOf(message), null);
  @@ -164,7 +195,11 @@
   
   
       /**
  -     * Log a message and exception with info log level.
  +     * Logs a message with <code>java.util.logging.Level.INFO</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#info(Object, Throwable)
        */
       public void info(Object message, Throwable exception) {
           log(Level.INFO, String.valueOf(message), exception);
  @@ -220,7 +255,10 @@
   
   
       /**
  -     * Log a message with trace log level.
  +     * Logs a message with <code>java.util.logging.Level.FINEST</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#trace(Object)
        */
       public void trace(Object message) {
           log(Level.FINEST, String.valueOf(message), null);
  @@ -228,7 +266,11 @@
   
   
       /**
  -     * Log a message and exception with trace log level.
  +     * Logs a message with <code>java.util.logging.Level.FINEST</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
        */
       public void trace(Object message, Throwable exception) {
           log(Level.FINEST, String.valueOf(message), exception);
  @@ -236,7 +278,10 @@
   
   
       /**
  -     * Log a message with warn log level.
  +     * Logs a message with <code>java.util.logging.Level.WARNING</code>.
  +     *
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#warn(Object)
        */
       public void warn(Object message) {
           log(Level.WARNING, String.valueOf(message), null);
  @@ -244,7 +289,11 @@
   
   
       /**
  -     * Log a message and exception with warn log level.
  +     * Logs a message with <code>java.util.logging.Level.WARNING</code>.
  +     *
  +     * @param message to log
  +     * @param exception log this cause
  +     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
        */
       public void warn(Object message, Throwable exception) {
           log(Level.WARNING, String.valueOf(message), exception);
  
  
  
  1.2       +293 -251  apache/commons-logging/src/java/org/apache/commons/logging/impl/LogKitLogger.java
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: LogKitLogger.java
  ===================================================================
  RCS file: /cvsroot/jboss/apache/commons-logging/src/java/org/apache/commons/logging/impl/LogKitLogger.java,v
  retrieving revision 1.1
  retrieving revision 1.2
  diff -u -b -r1.1 -r1.2
  --- LogKitLogger.java	17 Apr 2006 21:00:05 -0000	1.1
  +++ LogKitLogger.java	9 Feb 2007 06:57:15 -0000	1.2
  @@ -34,7 +34,7 @@
    *
    * @author <a href="mailto:sanders at apache.org">Scott Sanders</a>
    * @author Robert Burrell Donkin
  - * @version $Id: LogKitLogger.java,v 1.1 2006/04/17 21:00:05 starksm Exp $
  + * @version $Id: LogKitLogger.java,v 1.2 2007/02/09 06:57:15 starksm Exp $
    */
   
   public class LogKitLogger implements Log, Serializable {
  @@ -85,7 +85,10 @@
   
   
       /**
  -     * Log message to <code>LogKit</code> logger with <code>DEBUG</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.DEBUG</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#trace(Object)
        */
       public void trace(Object message) {
           debug(message);
  @@ -93,7 +96,11 @@
   
   
       /**
  -     * Log error to <code>LogKit</code> logger with <code>DEBUG</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.DEBUG</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#trace(Object, Throwable)
        */
       public void trace(Object message, Throwable t) {
           debug(message, t);
  @@ -101,7 +108,10 @@
   
   
       /**
  -     * Log message to <code>LogKit</code> logger with <code>DEBUG</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.DEBUG</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#debug(Object)
        */
       public void debug(Object message) {
           if (message != null) {
  @@ -111,7 +121,11 @@
   
   
       /**
  -     * Log error to <code>LogKit</code> logger with <code>DEBUG</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.DEBUG</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#debug(Object, Throwable)
        */
       public void debug(Object message, Throwable t) {
           if (message != null) {
  @@ -121,7 +135,10 @@
   
   
       /**
  -     * Log message to <code>LogKit</code> logger with <code>INFO</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.INFO</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#info(Object)
        */
       public void info(Object message) {
           if (message != null) {
  @@ -131,7 +148,11 @@
   
   
       /**
  -     * Log error to <code>LogKit</code> logger with <code>INFO</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.INFO</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#info(Object, Throwable)
        */
       public void info(Object message, Throwable t) {
           if (message != null) {
  @@ -141,7 +162,10 @@
   
   
       /**
  -     * Log message to <code>LogKit</code> logger with <code>WARN</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.WARN</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#warn(Object)
        */
       public void warn(Object message) {
           if (message != null) {
  @@ -151,7 +175,11 @@
   
   
       /**
  -     * Log error to <code>LogKit</code> logger with <code>WARN</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.WARN</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#warn(Object, Throwable)
        */
       public void warn(Object message, Throwable t) {
           if (message != null) {
  @@ -161,7 +189,10 @@
   
   
       /**
  -     * Log message to <code>LogKit</code> logger with <code>ERROR</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.ERROR</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#error(Object)
        */
       public void error(Object message) {
           if (message != null) {
  @@ -171,7 +202,11 @@
   
   
       /**
  -     * Log error to <code>LogKit</code> logger with <code>ERROR</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.ERROR</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#error(Object, Throwable)
        */
       public void error(Object message, Throwable t) {
           if (message != null) {
  @@ -181,7 +216,10 @@
   
   
       /**
  -     * Log message to <code>LogKit</code> logger with <code>FATAL_ERROR</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.FATAL_ERROR</code>.
  +     * 
  +     * @param message to log
  +     * @see org.apache.commons.logging.Log#fatal(Object)
        */
       public void fatal(Object message) {
           if (message != null) {
  @@ -191,7 +229,11 @@
   
   
       /**
  -     * Log error to <code>LogKit</code> logger with <code>FATAL_ERROR</code> priority.
  +     * Logs a message with <code>org.apache.log.Priority.FATAL_ERROR</code>.
  +     * 
  +     * @param message to log
  +     * @param t log this cause
  +     * @see org.apache.commons.logging.Log#fatal(Object, Throwable)
        */
       public void fatal(Object message, Throwable t) {
           if (message != null) {
  @@ -201,7 +243,7 @@
   
   
       /**
  -     * Check whether the <code>LogKit</code> logger will log messages of priority <code>DEBUG</code>.
  +     * Checks whether the <code>LogKit</code> logger will log messages of priority <code>DEBUG</code>.
        */
       public boolean isDebugEnabled() {
           return getLogger().isDebugEnabled();
  @@ -209,7 +251,7 @@
   
   
       /**
  -     * Check whether the <code>LogKit</code> logger will log messages of priority <code>ERROR</code>.
  +     * Checks whether the <code>LogKit</code> logger will log messages of priority <code>ERROR</code>.
        */
       public boolean isErrorEnabled() {
           return getLogger().isErrorEnabled();
  @@ -217,7 +259,7 @@
   
   
       /**
  -     * Check whether the <code>LogKit</code> logger will log messages of priority <code>FATAL_ERROR</code>.
  +     * Checks whether the <code>LogKit</code> logger will log messages of priority <code>FATAL_ERROR</code>.
        */
       public boolean isFatalEnabled() {
           return getLogger().isFatalErrorEnabled();
  @@ -225,7 +267,7 @@
   
   
       /**
  -     * Check whether the <code>LogKit</code> logger will log messages of priority <code>INFO</code>.
  +     * Checks whether the <code>LogKit</code> logger will log messages of priority <code>INFO</code>.
        */
       public boolean isInfoEnabled() {
           return getLogger().isInfoEnabled();
  @@ -233,7 +275,7 @@
   
   
       /**
  -     * Check whether the <code>LogKit</code> logger will log messages of priority <code>DEBUG</code>.
  +     * Checks whether the <code>LogKit</code> logger will log messages of priority <code>DEBUG</code>.
        */
       public boolean isTraceEnabled() {
           return getLogger().isDebugEnabled();
  @@ -241,7 +283,7 @@
   
   
       /**
  -     * Check whether the <code>LogKit</code> logger will log messages of priority <code>WARN</code>.
  +     * Checks whether the <code>LogKit</code> logger will log messages of priority <code>WARN</code>.
        */
       public boolean isWarnEnabled() {
           return getLogger().isWarnEnabled();
  
  
  
  1.1      date: 2007/02/09 06:57:15;  author: starksm;  state: Exp;apache/commons-logging/src/java/org/apache/commons/logging/impl/WeakHashtable.java
  
  Index: WeakHashtable.java
  ===================================================================
  /*
   * Copyright 2004 The Apache Software Foundation.
   * 
   * 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.
   */ 
  
  
  package org.apache.commons.logging.impl;
  
  import java.lang.ref.ReferenceQueue;
  import java.lang.ref.WeakReference;
  import java.util.*;
  
  /**
   * <p>Implementation of <code>Hashtable</code> that uses <code>WeakReference</code>'s
   * to hold its keys thus allowing them to be reclaimed by the garbage collector.
   * The associated values are retained using strong references.</p>
   *
   * <p>This class follows the symantics of <code>Hashtable</code> as closely as
   * possible. It therefore does not accept null values or keys.</p>
   *
   * <p><strong>Note:</strong>
   * This is <em>not</em> intended to be a general purpose hash table replacement.
   * This implementation is also tuned towards a particular purpose: for use as a replacement
   * for <code>Hashtable</code> in <code>LogFactory</code>. This application requires
   * good liveliness for <code>get</code> and <code>put</code>. Various tradeoffs
   * have been made with this in mind.
   * </p>
   * <p>
   * <strong>Usage:</strong> typical use case is as a drop-in replacement 
   * for the <code>Hashtable</code> used in <code>LogFactory</code> for J2EE enviroments
   * running 1.3+ JVMs. Use of this class <i>in most cases</i> (see below) will
   * allow classloaders to be collected by the garbage collector without the need 
   * to call {@link org.apache.commons.logging.LogFactory#release(ClassLoader) LogFactory.release(ClassLoader)}.
   * </p>
   *
   * <p><code>org.apache.commons.logging.LogFactory</code> checks whether this class
   * can be supported by the current JVM, and if so then uses it to store
   * references to the <code>LogFactory</code> implementationd it loads 
   * (rather than using a standard Hashtable instance). 
   * Having this class used instead of <code>Hashtable</code> solves
   * certain issues related to dynamic reloading of applications in J2EE-style
   * environments. However this class requires java 1.3 or later (due to its use
   * of <code>java.lang.ref.WeakReference</code> and associates).
   * And by the way, this extends <code>Hashtable</code> rather than <code>HashMap</code>
   * for backwards compatibility reasons. See the documentation
   * for method <code>LogFactory.createFactoryStore</code> for more details.</p>
   *
   * <p>The reason all this is necessary is due to a issue which
   * arises during hot deploy in a J2EE-like containers. 
   * Each component running in the container owns one or more classloaders; when
   * the component loads a LogFactory instance via the component classloader
   * a reference to it gets stored in the static LogFactory.factories member,
   * keyed by the component's classloader so different components don't
   * stomp on each other. When the component is later unloaded, the container
   * sets the component's classloader to null with the intent that all the 
   * component's classes get garbage-collected. However there's still a
   * reference to the component's classloader from a key in the "global"
   * <code>LogFactory</code>'s factories member! If <code>LogFactory.release()</code>
   * is called whenever component is unloaded, the classloaders will be correctly
   * garbage collected; this <i>should</i> be done by any container that 
   * bundles commons-logging by default. However, holding the classloader
   * references weakly ensures that the classloader will be garbage collected
   * without the container performing this step. </p>
   *
   * <p>
   * <strong>Limitations:</strong>
   * There is still one (unusual) scenario in which a component will not 
   * be correctly unloaded without an explicit release. Though weak references
   * are used for its keys, it is necessary to use strong references for its values.
   * </p>
   * 
   * <p> If the abstract class <code>LogFactory</code> is 
   * loaded by the container classloader but a subclass of 
   * <code>LogFactory</code> [LogFactory1] is loaded by the component's 
   * classloader and an instance stored in the static map associated with the
   * base LogFactory class, then there is a strong reference from the LogFactory
   * class to the LogFactory1 instance (as normal) and a strong reference from
   * the LogFactory1 instance to the component classloader via
   * <code>getClass().getClassLoader()</code>. This chain of references will prevent 
   * collection of the child classloader.</p>
   *
   * <p>
   * Such a situation occurs when the commons-logging.jar is
   * loaded by a parent classloader (e.g. a server level classloader in a
   * servlet container) and a custom <code>LogFactory</code> implementation is
   * loaded by a child classloader (e.g. a web app classloader).</p>
   * 
   * <p>To avoid this scenario, ensure
   * that any custom LogFactory subclass is loaded by the same classloader as 
   * the base <code>LogFactory</code>. Creating custom LogFactory subclasses is,
   * however, rare. The standard LogFactoryImpl class should be sufficient
   * for most or all users.</p>
   *
   *
   * @author Brian Stansberry
   * 
   * @since 1.1
   */
  public final class WeakHashtable extends Hashtable {
  
      /** 
       * The maximum number of times put() or remove() can be called before
       * the map will be purged of all cleared entries.
       */
      private static final int MAX_CHANGES_BEFORE_PURGE = 100;
      
      /** 
       * The maximum number of times put() or remove() can be called before
       * the map will be purged of one cleared entry.
       */
      private static final int PARTIAL_PURGE_COUNT     = 10;
      
      /* ReferenceQueue we check for gc'd keys */
      private ReferenceQueue queue = new ReferenceQueue();
      /* Counter used to control how often we purge gc'd entries */
      private int changeCount = 0;
      
      /**
       * Constructs a WeakHashtable with the Hashtable default
       * capacity and load factor.
       */
      public WeakHashtable() {}
      
      
      /**
       *@see Hashtable
       */
      public boolean containsKey(Object key) {
          // purge should not be required
          Referenced referenced = new Referenced(key);
          return super.containsKey(referenced);
      }
      
      /**
       *@see Hashtable
       */
      public Enumeration elements() {
          purge();
          return super.elements();
      }
      
      /**
       *@see Hashtable
       */
      public Set entrySet() {
          purge();
          Set referencedEntries = super.entrySet();
          Set unreferencedEntries = new HashSet();
          for (Iterator it=referencedEntries.iterator(); it.hasNext();) {
              Map.Entry entry = (Map.Entry) it.next();
              Referenced referencedKey = (Referenced) entry.getKey();
              Object key = referencedKey.getValue();
              Object value = entry.getValue();
              if (key != null) {
                  Entry dereferencedEntry = new Entry(key, value);
                  unreferencedEntries.add(dereferencedEntry);
              }
          }
          return unreferencedEntries;
      }
      
      /**
       *@see Hashtable
       */
      public Object get(Object key) {
          // for performance reasons, no purge
          Referenced referenceKey = new Referenced(key);
          return super.get(referenceKey);
      }
      
      /**
       *@see Hashtable
       */
      public Enumeration keys() {
          purge();
          final Enumeration enumer = super.keys();
          return new Enumeration() {
              public boolean hasMoreElements() {
                  return enumer.hasMoreElements();
              }
              public Object nextElement() {
                   Referenced nextReference = (Referenced) enumer.nextElement();
                   return nextReference.getValue();
              }
          };
      }
      
          
      /**
       *@see Hashtable
       */
      public Set keySet() {
          purge();
          Set referencedKeys = super.keySet();
          Set unreferencedKeys = new HashSet();
          for (Iterator it=referencedKeys.iterator(); it.hasNext();) {
              Referenced referenceKey = (Referenced) it.next();
              Object keyValue = referenceKey.getValue();
              if (keyValue != null) {
                  unreferencedKeys.add(keyValue);
              }
          }
          return unreferencedKeys;
      }
      
      /**
       *@see Hashtable
       */    
      public Object put(Object key, Object value) {
          // check for nulls, ensuring symantics match superclass
          if (key == null) {
              throw new NullPointerException("Null keys are not allowed");
          }
          if (value == null) {
              throw new NullPointerException("Null values are not allowed");
          }
  
          // for performance reasons, only purge every 
          // MAX_CHANGES_BEFORE_PURGE times
          if (changeCount++ > MAX_CHANGES_BEFORE_PURGE) {
              purge();
              changeCount = 0;
          }
          // do a partial purge more often
          else if ((changeCount % PARTIAL_PURGE_COUNT) == 0) {
              purgeOne();
          }
          
          Object result = null;
          Referenced keyRef = new Referenced(key, queue);
          return super.put(keyRef, value);
      }
      
      /**
       *@see Hashtable
       */    
      public void putAll(Map t) {
          if (t != null) {
              Set entrySet = t.entrySet();
              for (Iterator it=entrySet.iterator(); it.hasNext();) {
                  Map.Entry entry = (Map.Entry) it.next();
                  put(entry.getKey(), entry.getValue());
              }
          }
      }
      
      /**
       *@see Hashtable
       */      
      public Collection values() {
          purge();
          return super.values();
      }
      
      /**
       *@see Hashtable
       */     
      public Object remove(Object key) {
          // for performance reasons, only purge every 
          // MAX_CHANGES_BEFORE_PURGE times
          if (changeCount++ > MAX_CHANGES_BEFORE_PURGE) {
              purge();
              changeCount = 0;
          }
          // do a partial purge more often
          else if ((changeCount % PARTIAL_PURGE_COUNT) == 0) {
              purgeOne();
          }
          return super.remove(new Referenced(key));
      }
      
      /**
       *@see Hashtable
       */    
      public boolean isEmpty() {
          purge();
          return super.isEmpty();
      }
      
      /**
       *@see Hashtable
       */    
      public int size() {
          purge();
          return super.size();
      }
      
      /**
       *@see Hashtable
       */        
      public String toString() {
          purge();
          return super.toString();
      }
      
      /**
       * @see Hashtable
       */
      protected void rehash() {
          // purge here to save the effort of rehashing dead entries
          purge();
          super.rehash();
      }
      
      /**
       * Purges all entries whose wrapped keys
       * have been garbage collected.
       */
      private void purge() {
          synchronized (queue) {
              WeakKey key;
              while ((key = (WeakKey) queue.poll()) != null) {
                  super.remove(key.getReferenced());
              }
          }
      }
      
      /**
       * Purges one entry whose wrapped key 
       * has been garbage collected.
       */
      private void purgeOne() {
          
          synchronized (queue) {
              WeakKey key = (WeakKey) queue.poll();
              if (key != null) {
                  super.remove(key.getReferenced());
              }
          }
      }
      
      /** Entry implementation */
      private final static class Entry implements Map.Entry {
      
          private final Object key;
          private final Object value;
          
          private Entry(Object key, Object value) {
              this.key = key;
              this.value = value;
          }
      
          public boolean equals(Object o) {
              boolean result = false;
              if (o != null && o instanceof Map.Entry) {
                  Map.Entry entry = (Map.Entry) o;
                  result =    (getKey()==null ?
                                              entry.getKey() == null : 
                                              getKey().equals(entry.getKey()))
                              &&
                              (getValue()==null ?
                                              entry.getValue() == null : 
                                              getValue().equals(entry.getValue()));
              }
              return result;
          } 
          
          public int hashCode() {
  
              return (getKey()==null ? 0 : getKey().hashCode()) ^
                  (getValue()==null ? 0 : getValue().hashCode());
          }
  
          public Object setValue(Object value) {
              throw new UnsupportedOperationException("Entry.setValue is not supported.");
          }
          
          public Object getValue() {
              return value;
          }
          
          public Object getKey() {
              return key;
          }
      }
      
      
      /** Wrapper giving correct symantics for equals and hashcode */
      private final static class Referenced {
          
          private final WeakReference reference;
          private final int           hashCode;
  
          /**
           * 
           * @throws NullPointerException if referant is <code>null</code>
           */        
          private Referenced(Object referant) {
              reference = new WeakReference(referant);
              // Calc a permanent hashCode so calls to Hashtable.remove()
              // work if the WeakReference has been cleared
              hashCode  = referant.hashCode();
          }
          
          /**
           * 
           * @throws NullPointerException if key is <code>null</code>
           */
          private Referenced(Object key, ReferenceQueue queue) {
              reference = new WeakKey(key, queue, this);
              // Calc a permanent hashCode so calls to Hashtable.remove()
              // work if the WeakReference has been cleared
              hashCode  = key.hashCode();
  
          }
          
          public int hashCode() {
              return hashCode;
          }
          
          private Object getValue() {
              return reference.get();
          }
          
          public boolean equals(Object o) {
              boolean result = false;
              if (o instanceof Referenced) {
                  Referenced otherKey = (Referenced) o;
                  Object thisKeyValue = getValue();
                  Object otherKeyValue = otherKey.getValue();
                  if (thisKeyValue == null) {                     
                      result = (otherKeyValue == null);
                      
                      // Since our hashcode was calculated from the original
                      // non-null referant, the above check breaks the 
                      // hashcode/equals contract, as two cleared Referenced
                      // objects could test equal but have different hashcodes.
                      // We can reduce (not eliminate) the chance of this
                      // happening by comparing hashcodes.
                      if (result == true) {
                          result = (this.hashCode() == otherKey.hashCode());
                      }
                      // In any case, as our c'tor does not allow null referants
                      // and Hashtable does not do equality checks between 
                      // existing keys, normal hashtable operations should never 
                      // result in an equals comparison between null referants
                  }
                  else
                  {
                      result = thisKeyValue.equals(otherKeyValue);
                  }
              }
              return result;
          }
      }
      
      /**
       * WeakReference subclass that holds a hard reference to an
       * associated <code>value</code> and also makes accessible
       * the Referenced object holding it.
       */
      private final static class WeakKey extends WeakReference {
  
          private final Referenced referenced;
          
          private WeakKey(Object key, 
                          ReferenceQueue queue,
                          Referenced referenced) {
              super(key, queue);
              this.referenced = referenced;
          }
          
          private Referenced getReferenced() {
              return referenced;
          }
       }
  }
  
  
  
  1.1      date: 2007/02/09 06:57:15;  author: starksm;  state: Exp;apache/commons-logging/src/java/org/apache/commons/logging/impl/ServletContextCleaner.java
  
  Index: ServletContextCleaner.java
  ===================================================================
  /*
   * Copyright 2005 The Apache Software Foundation.
   * 
   * 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.
   */ 
  
  
  package org.apache.commons.logging.impl;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  
  import javax.servlet.ServletContextEvent;
  import javax.servlet.ServletContextListener;
  
  import org.apache.commons.logging.LogFactory;
  
  
  /**
   * This class is capable of receiving notifications about the undeployment of
   * a webapp, and responds by ensuring that commons-logging releases all
   * memory associated with the undeployed webapp.
   * <p>
   * In general, the WeakHashtable support added in commons-logging release 1.1
   * ensures that logging classes do not hold references that prevent an
   * undeployed webapp's memory from being garbage-collected even when multiple
   * copies of commons-logging are deployed via multiple classloaders (a
   * situation that earlier versions had problems with). However there are
   * some rare cases where the WeakHashtable approach does not work; in these
   * situations specifying this class as a listener for the web application will
   * ensure that all references held by commons-logging are fully released.
   * <p>
   * To use this class, configure the webapp deployment descriptor to call
   * this class on webapp undeploy; the contextDestroyed method will tell
   * every accessable LogFactory class that the entry in its map for the
   * current webapp's context classloader should be cleared.
   * 
   * @since 1.1
   */
  
  public class ServletContextCleaner implements ServletContextListener {
  
      private Class[] RELEASE_SIGNATURE = {ClassLoader.class};
      
      /**
       * Invoked when a webapp is undeployed, this tells the LogFactory
       * class to release any logging information related to the current
       * contextClassloader.
       */
      public void contextDestroyed(ServletContextEvent sce) {
          ClassLoader tccl = Thread.currentThread().getContextClassLoader();
  
          Object[] params = new Object[1];
          params[0] = tccl;
  
          // Walk up the tree of classloaders, finding all the available
          // LogFactory classes and releasing any objects associated with
          // the tccl (ie the webapp).
          //
          // When there is only one LogFactory in the classpath, and it
          // is within the webapp being undeployed then there is no problem;
          // garbage collection works fine.
          //
          // When there are multiple LogFactory classes in the classpath but
          // parent-first classloading is used everywhere, this loop is really
          // short. The first instance of LogFactory found will
          // be the highest in the classpath, and then no more will be found.
          // This is ok, as with this setup this will be the only LogFactory
          // holding any data associated with the tccl being released.
          //
          // When there are multiple LogFactory classes in the classpath and
          // child-first classloading is used in any classloader, then multiple
          // LogFactory instances may hold info about this TCCL; whenever the
          // webapp makes a call into a class loaded via an ancestor classloader
          // and that class calls LogFactory the tccl gets registered in
          // the LogFactory instance that is visible from the ancestor
          // classloader. However the concrete logging library it points
          // to is expected to have been loaded via the TCCL, so the 
          // underlying logging lib is only initialised/configured once.
          // These references from ancestor LogFactory classes down to
          // TCCL classloaders are held via weak references and so should
          // be released but there are circumstances where they may not.
          // Walking up the classloader ancestry ladder releasing
          // the current tccl at each level tree, though, will definitely
          // clear any problem references.
          ClassLoader loader = tccl;
          while (loader != null) {
              // Load via the current loader. Note that if the class is not accessable
              // via this loader, but is accessable via some ancestor then that class
              // will be returned.
              try {
                  Class logFactoryClass = loader.loadClass("org.apache.commons.logging.LogFactory");
                  Method releaseMethod = logFactoryClass.getMethod("release", RELEASE_SIGNATURE);
                  releaseMethod.invoke(null, params);
                  loader = logFactoryClass.getClassLoader().getParent();
              } catch(ClassNotFoundException ex) {
                  // Neither the current classloader nor any of its ancestors could find
                  // the LogFactory class, so we can stop now.
                  loader = null;
              } catch(NoSuchMethodException ex) {
                  // This is not expected; every version of JCL has this method
                  System.err.println("LogFactory instance found which does not support release method!");
                  loader = null;
              } catch(IllegalAccessException ex) {
                  // This is not expected; every ancestor class should be accessable
                  System.err.println("LogFactory instance found which is not accessable!");
                  loader = null;
              } catch(InvocationTargetException ex) {
                  // This is not expected
                  System.err.println("LogFactory instance release method failed!");
                  loader = null;
              }
          }
          
          // Just to be sure, invoke release on the LogFactory that is visible from
          // this ServletContextCleaner class too. This should already have been caught
          // by the above loop but just in case...
          LogFactory.release(tccl);
      }
      
      /**
       * Invoked when a webapp is deployed. Nothing needs to be done here.
       */
      public void contextInitialized(ServletContextEvent sce) {
          // do nothing
      }
  }
  
  
  



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