src/java/org/apache/log4j/Hierarchy.java - logging-log4j1 - Git at Google

 /*
  * Copyright (C) The Apache Software Foundation. All rights reserved.
  *
  * This software is published under the terms of the Apache Software
  * License version 1.1, a copy of which has been included with this
  * distribution in the LICENSE.txt file.  */

 // WARNING This class MUST not have references to the Category or
 // WARNING RootCategory classes in its static initiliazation neither
 // WARNING directly nor indirectly.

 // Contributors:
 //                Luke Blanshard <luke@quiq.com>
 //                Mario Schomburg - IBM Global Services/Germany
 //                Anders Kristensen
 //                Igor Poteryaev

 package org.apache.log4j;


 import java.util.Hashtable;
 import java.util.Enumeration;
 import java.util.Vector;

 import org.apache.log4j.spi.RootCategory;
 import org.apache.log4j.spi.CategoryFactory;
 import org.apache.log4j.spi.HierarchyEventListener;
 import org.apache.log4j.Appender;
 import org.apache.log4j.or.RendererMap;
 import org.apache.log4j.or.ObjectRenderer;
 import org.apache.log4j.helpers.LogLog;
 import org.apache.log4j.helpers.OptionConverter;

 /**
    This class is specialized in retrieving categories by name and
    also maintaining the category hierarchy.

    <p><em>The casual user should not have to deal with this class
    directly.</em> In fact, up until version 0.9.0, this class had
    default package access.

    <p>The structure of the category hierarchy is maintained by the
    {@link #getInstance} method. The hierarchy is such that children
    link to their parent but parents do not have any pointers to their
    children. Moreover, categories can be instantiated in any order, in
    particular descendant before ancestor.

    <p>In case a descendant is created before a particular ancestor,
    then it creates a provision node for the ancestor and adds itself
    to the provision node. Other descendants of the same ancestor add
    themselves to the previously created provision node.

    @author Ceki G&uuml;lc&uuml;

 */
 public class Hierarchy {

   private CategoryFactory defaultFactory;
   private Vector listeners;

   Hashtable ht;
   Category root;
   RendererMap rendererMap;

   int enableInt;
   Level enable;

   boolean emittedNoAppenderWarning = false;
   boolean emittedNoResourceBundleWarning = false;

   /**
      Create a new Category hierarchy.

      @param root The root of the new hierarchy.

    */
   public
   Hierarchy(Category root) {
     ht = new Hashtable();
     listeners = new Vector(1);
     this.root = root;
     // Enable all level levels by default.
     enable(Level.ALL);
     this.root.setHierarchy(this);
     rendererMap = new RendererMap();
     defaultFactory = new DefaultCategoryFactory();
   }

   /**
      Add an object renderer for a specific class.
    */
   public
   void addRenderer(Class classToRender, ObjectRenderer or) {
     rendererMap.put(classToRender, or);
   }

   public
   void addHierarchyEventListener(HierarchyEventListener listener) {
     if(listeners.contains(listener)) {
       LogLog.warn("Ignoring attempt to add an existent listener.");
     } else {
       listeners.add(listener);
     }
   }

   /**
      This call will clear all category definitions from the internal
      hashtable. Invoking this method will irrevocably mess up the
      category hierarchy.

      <p>You should <em>really</em> know what you are doing before
      invoking this method.

      @since 0.9.0 */
   public
   void clear() {
     //System.out.println("\n\nAbout to clear internal hash table.");
     ht.clear();
   }

   /**
      Check if the named category exists in the hierarchy. If so return
      its reference, otherwise returns <code>null</code>.

      @param name The name of the category to search for.

   */
   public
   Category exists(String name) {
     Object o = ht.get(new CategoryKey(name));
     if(o instanceof Category) {
       return (Category) o;
     } else {
       return null;
     }
   }


   /**
      Similar to {@link #disable(Level)} except that the level
      argument is given as a String.

      @deprecated Replaced with the {@link #enable(Level)} familiy
      of methods
   */
   public
   void disable(String levelStr) {
     Level p = Level.toLevel(levelStr, null);
     if(p != null) {
       disable(p);
     } else {
       LogLog.warn("Could not convert ["+levelStr+"] to Level.");
     }
   }


   /**
      Disable all logging requests of level <em>equal to or
      below</em> the level parameter <code>p</code>, for
      <em>all</em> categories in this hierarchy. Logging requests of
      higher level then <code>p</code> remain unaffected.

      <p>The "disable" family of methods are there for speed. They
      allow printing methods such as debug, info, etc. to return
      immediately after an integer comparison without walking the
      category hierarchy. In most modern computers an integer
      comparison is measured in nanoseconds where as a category walk is
      measured in units of microseconds.

      <p>Other configurators define alternate ways of overriding the
      disable override flag. See {@link PropertyConfigurator} and
      {@link org.apache.log4j.xml.DOMConfigurator}.

      @deprecated Please use the {@link #enable} familiy of methods instead.

      @since 0.8.5 */
   public
   void disable(Level p) {
     if(p != null) {
       switch(p.level) {
       case Level.ALL_INT: enable(Level.ALL); break;
       case Level.DEBUG_INT: enable(Level.INFO); break;
       case Level.INFO_INT: enable(Level.WARN); break;
       case Level.WARN_INT: enable(Level.ERROR); break;
       case Level.ERROR_INT: enable(Level.FATAL); break;
       case Level.FATAL_INT: enable(Level.OFF); break;
       case Level.OFF_INT: enable(Level.OFF); break;
       default:
       }
     }
   }

   /**
      Disable all logging requests regardless of category and level.
      This method is equivalent to calling {@link #disable} with the
      argument {@link Level#FATAL}, the highest possible level.

      @deprecated Please use the {@link #enable} familiy of methods instead.

      @since 0.8.5 */
   public
   void disableAll() {
     disable(Level.FATAL);
   }


   /**
      Disable all logging requests of level DEBUG regardless of
      category.  Invoking this method is equivalent to calling {@link
      #disable} with the argument {@link Level#DEBUG}.

      @deprecated Please use the {@link #enable} familiy of methods instead.

      @since 0.8.5 */
   public
   void disableDebug() {
     disable(Level.DEBUG);
   }


   /**
      Disable all logging requests of level INFO and below
      regardless of category. Note that DEBUG messages are also
      disabled.

      <p>Invoking this method is equivalent to calling {@link
      #disable(Level)} with the argument {@link Level#INFO}.

      @deprecated Please use the {@link #enable} familiy of methods instead.

      @since 0.8.5 */
   public
   void disableInfo() {
     disable(Level.INFO);
   }

   /**
      Undoes the effect of calling any of {@link #disable}, {@link
      #disableAll}, {@link #disableDebug} and {@link #disableInfo}
      methods. More precisely, invoking this method sets the Category
      class internal variable called <code>disable</code> to its
      default "off" value.

      @since 0.8.5 */
   public
   void enableAll() {
     enable(Level.ALL);
   }

   /**
      Enable logging for events with level p or higher.

 	  @param p the minimum level for which events are sent to
 	         their appenders.
 	  @since 1.1.3 */
   public
   void enable(Level p) {
     if(p != null) {
       enableInt = p.level;
       enable = p;
     }
   }


   void fireAddAppenderEvent(Category category, Appender appender) {
     if(listeners != null) {
       int size = listeners.size();
       HierarchyEventListener listener;
       for(int i = 0; i < size; i++) {
 	listener = (HierarchyEventListener) listeners.elementAt(i);
 	listener.addAppenderEvent(category, appender);
       }
     }
   }


   void fireRemoveAppenderEvent(Category category, Appender appender) {
     if(listeners != null) {
       int size = listeners.size();
       HierarchyEventListener listener;
       for(int i = 0; i < size; i++) {
 	listener = (HierarchyEventListener) listeners.elementAt(i);
 	listener.removeAppenderEvent(category, appender);
       }
     }
   }

   /**
      Returns a {@link Level} representation of the
      <code>enable</code> state.

      @since 1.2
   */
   public
   Level getEnable() {
     return enable;
   }

   /**
      Return a new category instance named as the first parameter using
      the default factory.

      <p>If a category of that name already exists, then it will be
      returned.  Otherwise, a new category will be instantiated and
      then linked with its existing ancestors as well as children.

      @param name The name of the category to retrieve.

  */
   public
   Category getInstance(String name) {
     return getInstance(name, defaultFactory);
   }

  /**
      Return a new category instance named as the first parameter using
      <code>factory</code>.

      <p>If a category of that name already exists, then it will be
      returned.  Otherwise, a new category will be instantiated by the
      <code>factory</code> parameter and linked with its existing
      ancestors as well as children.

      @param name The name of the category to retrieve.
      @param factory The factory that will make the new category instance.

  */
   public
   Category getInstance(String name, CategoryFactory factory) {
     //System.out.println("getInstance("+name+") called.");
     CategoryKey key = new CategoryKey(name);
     // Synchronize to prevent write conflicts. Read conflicts (in
     // getChainedLevel method) are possible only if variable
     // assignments are non-atomic.
     Category category;

     synchronized(ht) {
       Object o = ht.get(key);
       if(o == null) {
 	category = factory.makeNewCategoryInstance(name);
 	category.setHierarchy(this);
 	ht.put(key, category);
 	updateParents(category);
 	return category;
       } else if(o instanceof Category) {
 	return (Category) o;
       } else if (o instanceof ProvisionNode) {
 	//System.out.println("("+name+") ht.get(this) returned ProvisionNode");
 	category = factory.makeNewCategoryInstance(name);
 	category.setHierarchy(this);
 	ht.put(key, category);
 	updateChildren((ProvisionNode) o, category);
 	updateParents(category);
 	return category;
       }
       else {
 	// It should be impossible to arrive here
 	return null;  // but let's keep the compiler happy.
       }
     }
   }


   /**
      Returns all the currently defined categories in this hierarchy as
      an {@link java.util.Enumeration Enumeration}.

      <p>The root category is <em>not</em> included in the returned
      {@link Enumeration}.  */
   public
   Enumeration getCurrentCategories() {
     // The accumlation in v is necessary because not all elements in
     // ht are Category objects as there might be some ProvisionNodes
     // as well.
     Vector v = new Vector(ht.size());

     Enumeration elems = ht.elements();
     while(elems.hasMoreElements()) {
       Object o = elems.nextElement();
       if(o instanceof Category) {
 	v.addElement(o);
       }
     }
     return v.elements();
   }

   /**
      Get the renderer map for this hierarchy.
   */
   public
   RendererMap getRendererMap() {
     return rendererMap;
   }


   /**
      Get the root of this hierarchy.

      @since 0.9.0
    */
   public
   Category getRoot() {
     return root;
   }

   /**
      @deprecated See {@link #getEnable} for similar functionality.
    */

   public
   boolean isDisabled(int level) {
     return enableInt >  level;
   }

   /**
      @deprecated Deprecated with no replacement.
   */
   public
   void overrideAsNeeded(String override) {
     LogLog.warn("The Hiearchy.overrideAsNeeded method has been deprecated.");
   }

   /**
      Reset all values contained in this hierarchy instance to their
      default.  This removes all appenders from all categories, sets
      the level of all non-root categories to <code>null</code>,
      sets their additivity flag to <code>true</code> and sets the level
      of the root category to {@link Level#DEBUG DEBUG}.  Moreover,
      message disabling is set its default "off" value.

      <p>Existing categories are not removed. They are just reset.

      <p>This method should be used sparingly and with care as it will
      block all logging until it is completed.</p>

      @since 0.8.5 */
   public
   void resetConfiguration() {

     getRoot().setLevel(Level.DEBUG);
     root.setResourceBundle(null);
     enableAll();

     // the synchronization is needed to prevent JDK 1.2.x hashtable
     // surprises
     synchronized(ht) {
       shutdown(); // nested locks are OK

       Enumeration cats = getCurrentCategories();
       while(cats.hasMoreElements()) {
 	Category c = (Category) cats.nextElement();
 	c.setLevel(null);
 	c.setAdditivity(true);
 	c.setResourceBundle(null);
       }
     }
     rendererMap.clear();
   }

   /**
      Set the default CategoryFactory instance.

      @since 1.1
    */
   public void setCategoryFactory(CategoryFactory factory) {
     if (factory != null) {
       defaultFactory = factory;
     }
   }

   /**
      Does mothing.

      @deprecated Deprecated with no replacement.
    */
   public
   void setDisableOverride(String override) {
     LogLog.warn("The Hiearchy.setDisableOverride method has been deprecated.");
   }

   /**
      Shutting down a hierarchy will <em>safely</em> close and remove
      all appenders in all categories including the root category.

      <p>Some appenders such as {@link org.apache.log4j.net.SocketAppender}
      and {@link AsyncAppender} need to be closed before the
      application exists. Otherwise, pending logging events might be
      lost.

      <p>The <code>shutdown</code> method is careful to close nested
      appenders before closing regular appenders. This is allows
      configurations where a regular appender is attached to a category
      and again to a nested appender.


      @since 1.0 */
   public
   void shutdown() {
     Category root = getRoot();

     // begin by closing nested appenders
     root.closeNestedAppenders();

     synchronized(ht) {
       Enumeration cats = this.getCurrentCategories();
       while(cats.hasMoreElements()) {
 	Category c = (Category) cats.nextElement();
 	c.closeNestedAppenders();
       }

       // then, remove all appenders
       root.removeAllAppenders();
       cats = this.getCurrentCategories();
       while(cats.hasMoreElements()) {
 	Category c = (Category) cats.nextElement();
 	c.removeAllAppenders();
       }
     }
   }


   /**
      This method loops through all the *potential* parents of
      'cat'. There 3 possible cases:

      1) No entry for the potential parent of 'cat' exists

         We create a ProvisionNode for this potential parent and insert
         'cat' in that provision node.

      2) There entry is of type Category for the potential parent.

         The entry is 'cat's nearest existing parent. We update cat's
         parent field with this entry. We also break from the loop
         because updating our parent's parent is our parent's
         responsibility.

      3) There entry is of type ProvisionNode for this potential parent.

         We add 'cat' to the list of children for this potential parent.
    */
   final
   private
   void updateParents(Category cat) {
     String name = cat.name;
     int length = name.length();
     boolean parentFound = false;

     //System.out.println("UpdateParents called for " + name);

     // if name = "w.x.y.z", loop thourgh "w.x.y", "w.x" and "w", but not "w.x.y.z"
     for(int i = name.lastIndexOf('.', length-1); i >= 0;
 	                                 i = name.lastIndexOf('.', i-1))  {
       String substr = name.substring(0, i);

       //System.out.println("Updating parent : " + substr);
       CategoryKey key = new CategoryKey(substr); // simple constructor
       Object o = ht.get(key);
       // Create a provision node for a future parent.
       if(o == null) {
 	//System.out.println("No parent "+substr+" found. Creating ProvisionNode.");
 	ProvisionNode pn = new ProvisionNode(cat);
 	ht.put(key, pn);
       } else if(o instanceof Category) {
 	parentFound = true;
 	cat.parent = (Category) o;
 	//System.out.println("Linking " + cat.name + " -> " + ((Category) o).name);
 	break; // no need to update the ancestors of the closest ancestor
       } else if(o instanceof ProvisionNode) {
 	((ProvisionNode) o).addElement(cat);
       } else {
 	Exception e = new IllegalStateException("unexpected object type " +
 					o.getClass() + " in ht.");
 	e.printStackTrace();
       }
     }
     // If we could not find any existing parents, then link with root.
     if(!parentFound)
       cat.parent = root;
   }

   /**
       We update the links for all the children that placed themselves
       in the provision node 'pn'. The second argument 'cat' is a
       reference for the newly created Category, parent of all the
       children in 'pn'

       We loop on all the children 'c' in 'pn':

          If the child 'c' has been already linked to a child of
          'cat' then there is no need to update 'c'.

 	 Otherwise, we set cat's parent field to c's parent and set
 	 c's parent field to cat.

   */
   final
   private
   void updateChildren(ProvisionNode pn, Category cat) {
     //System.out.println("updateChildren called for " + cat.name);
     final int last = pn.size();

     for(int i = 0; i < last; i++) {
       Category c = (Category) pn.elementAt(i);
       //System.out.println("Updating child " +p.name);

       // Unless this child already points to a correct (lower) parent,
       // make cat.parent point to c.parent and c.parent to cat.
       if(!c.parent.name.startsWith(cat.name)) {
 	cat.parent = c.parent;
 	c.parent = cat;
       }
     }
   }

 }
	/*
	* Copyright (C) The Apache Software Foundation. All rights reserved.
	*
	* This software is published under the terms of the Apache Software
	* License version 1.1, a copy of which has been included with this
	* distribution in the LICENSE.txt file. */

	// WARNING This class MUST not have references to the Category or
	// WARNING RootCategory classes in its static initiliazation neither
	// WARNING directly nor indirectly.

	// Contributors:
	// Luke Blanshard <luke@quiq.com>
	// Mario Schomburg - IBM Global Services/Germany
	// Anders Kristensen
	// Igor Poteryaev

	package org.apache.log4j;


	import java.util.Hashtable;
	import java.util.Enumeration;
	import java.util.Vector;

	import org.apache.log4j.spi.RootCategory;
	import org.apache.log4j.spi.CategoryFactory;
	import org.apache.log4j.spi.HierarchyEventListener;
	import org.apache.log4j.Appender;
	import org.apache.log4j.or.RendererMap;
	import org.apache.log4j.or.ObjectRenderer;
	import org.apache.log4j.helpers.LogLog;
	import org.apache.log4j.helpers.OptionConverter;

	/**
	This class is specialized in retrieving categories by name and
	also maintaining the category hierarchy.

	<p><em>The casual user should not have to deal with this class
	directly.</em> In fact, up until version 0.9.0, this class had
	default package access.

	<p>The structure of the category hierarchy is maintained by the
	{@link #getInstance} method. The hierarchy is such that children
	link to their parent but parents do not have any pointers to their
	children. Moreover, categories can be instantiated in any order, in
	particular descendant before ancestor.

	<p>In case a descendant is created before a particular ancestor,
	then it creates a provision node for the ancestor and adds itself
	to the provision node. Other descendants of the same ancestor add
	themselves to the previously created provision node.

	@author Ceki Gülcü

	*/
	public class Hierarchy {

	private CategoryFactory defaultFactory;
	private Vector listeners;

	Hashtable ht;
	Category root;
	RendererMap rendererMap;

	int enableInt;
	Level enable;

	boolean emittedNoAppenderWarning = false;
	boolean emittedNoResourceBundleWarning = false;

	/**
	Create a new Category hierarchy.

	@param root The root of the new hierarchy.

	*/
	public
	Hierarchy(Category root) {
	ht = new Hashtable();
	listeners = new Vector(1);
	this.root = root;
	// Enable all level levels by default.
	enable(Level.ALL);
	this.root.setHierarchy(this);
	rendererMap = new RendererMap();
	defaultFactory = new DefaultCategoryFactory();
	}

	/**
	Add an object renderer for a specific class.
	*/
	public
	void addRenderer(Class classToRender, ObjectRenderer or) {
	rendererMap.put(classToRender, or);
	}

	public
	void addHierarchyEventListener(HierarchyEventListener listener) {
	if(listeners.contains(listener)) {
	LogLog.warn("Ignoring attempt to add an existent listener.");
	} else {
	listeners.add(listener);
	}
	}

	/**
	This call will clear all category definitions from the internal
	hashtable. Invoking this method will irrevocably mess up the
	category hierarchy.

	<p>You should <em>really</em> know what you are doing before
	invoking this method.

	@since 0.9.0 */
	public
	void clear() {
	//System.out.println("\n\nAbout to clear internal hash table.");
	ht.clear();
	}

	/**
	Check if the named category exists in the hierarchy. If so return
	its reference, otherwise returns <code>null</code>.

	@param name The name of the category to search for.

	*/
	public
	Category exists(String name) {
	Object o = ht.get(new CategoryKey(name));
	if(o instanceof Category) {
	return (Category) o;
	} else {
	return null;
	}
	}


	/**
	Similar to {@link #disable(Level)} except that the level
	argument is given as a String.

	@deprecated Replaced with the {@link #enable(Level)} familiy
	of methods
	*/
	public
	void disable(String levelStr) {
	Level p = Level.toLevel(levelStr, null);
	if(p != null) {
	disable(p);
	} else {
	LogLog.warn("Could not convert ["+levelStr+"] to Level.");
	}
	}


	/**
	Disable all logging requests of level <em>equal to or
	below</em> the level parameter <code>p</code>, for
	<em>all</em> categories in this hierarchy. Logging requests of
	higher level then <code>p</code> remain unaffected.

	<p>The "disable" family of methods are there for speed. They
	allow printing methods such as debug, info, etc. to return
	immediately after an integer comparison without walking the
	category hierarchy. In most modern computers an integer
	comparison is measured in nanoseconds where as a category walk is
	measured in units of microseconds.

	<p>Other configurators define alternate ways of overriding the
	disable override flag. See {@link PropertyConfigurator} and
	{@link org.apache.log4j.xml.DOMConfigurator}.

	@deprecated Please use the {@link #enable} familiy of methods instead.

	@since 0.8.5 */
	public
	void disable(Level p) {
	if(p != null) {
	switch(p.level) {
	case Level.ALL_INT: enable(Level.ALL); break;
	case Level.DEBUG_INT: enable(Level.INFO); break;
	case Level.INFO_INT: enable(Level.WARN); break;
	case Level.WARN_INT: enable(Level.ERROR); break;
	case Level.ERROR_INT: enable(Level.FATAL); break;
	case Level.FATAL_INT: enable(Level.OFF); break;
	case Level.OFF_INT: enable(Level.OFF); break;
	default:
	}
	}
	}

	/**
	Disable all logging requests regardless of category and level.
	This method is equivalent to calling {@link #disable} with the
	argument {@link Level#FATAL}, the highest possible level.

	@deprecated Please use the {@link #enable} familiy of methods instead.

	@since 0.8.5 */
	public
	void disableAll() {
	disable(Level.FATAL);
	}


	/**
	Disable all logging requests of level DEBUG regardless of
	category. Invoking this method is equivalent to calling {@link
	#disable} with the argument {@link Level#DEBUG}.

	@deprecated Please use the {@link #enable} familiy of methods instead.

	@since 0.8.5 */
	public
	void disableDebug() {
	disable(Level.DEBUG);
	}


	/**
	Disable all logging requests of level INFO and below
	regardless of category. Note that DEBUG messages are also
	disabled.

	<p>Invoking this method is equivalent to calling {@link
	#disable(Level)} with the argument {@link Level#INFO}.

	@deprecated Please use the {@link #enable} familiy of methods instead.

	@since 0.8.5 */
	public
	void disableInfo() {
	disable(Level.INFO);
	}

	/**
	Undoes the effect of calling any of {@link #disable}, {@link
	#disableAll}, {@link #disableDebug} and {@link #disableInfo}
	methods. More precisely, invoking this method sets the Category
	class internal variable called <code>disable</code> to its
	default "off" value.

	@since 0.8.5 */
	public
	void enableAll() {
	enable(Level.ALL);
	}

	/**
	Enable logging for events with level p or higher.

	@param p the minimum level for which events are sent to
	their appenders.
	@since 1.1.3 */
	public
	void enable(Level p) {
	if(p != null) {
	enableInt = p.level;
	enable = p;
	}
	}



	void fireAddAppenderEvent(Category category, Appender appender) {
	if(listeners != null) {
	int size = listeners.size();
	HierarchyEventListener listener;
	for(int i = 0; i < size; i++) {
	listener = (HierarchyEventListener) listeners.elementAt(i);
	listener.addAppenderEvent(category, appender);
	}
	}
	}


	void fireRemoveAppenderEvent(Category category, Appender appender) {
	if(listeners != null) {
	int size = listeners.size();
	HierarchyEventListener listener;
	for(int i = 0; i < size; i++) {
	listener = (HierarchyEventListener) listeners.elementAt(i);
	listener.removeAppenderEvent(category, appender);
	}
	}
	}

	/**
	Returns a {@link Level} representation of the
	<code>enable</code> state.

	@since 1.2
	*/
	public
	Level getEnable() {
	return enable;
	}

	/**
	Return a new category instance named as the first parameter using
	the default factory.

	<p>If a category of that name already exists, then it will be
	returned. Otherwise, a new category will be instantiated and
	then linked with its existing ancestors as well as children.

	@param name The name of the category to retrieve.

	*/
	public
	Category getInstance(String name) {
	return getInstance(name, defaultFactory);
	}

	/**
	Return a new category instance named as the first parameter using
	<code>factory</code>.

	<p>If a category of that name already exists, then it will be
	returned. Otherwise, a new category will be instantiated by the
	<code>factory</code> parameter and linked with its existing
	ancestors as well as children.

	@param name The name of the category to retrieve.
	@param factory The factory that will make the new category instance.

	*/
	public
	Category getInstance(String name, CategoryFactory factory) {
	//System.out.println("getInstance("+name+") called.");
	CategoryKey key = new CategoryKey(name);
	// Synchronize to prevent write conflicts. Read conflicts (in
	// getChainedLevel method) are possible only if variable
	// assignments are non-atomic.
	Category category;

	synchronized(ht) {
	Object o = ht.get(key);
	if(o == null) {
	category = factory.makeNewCategoryInstance(name);
	category.setHierarchy(this);
	ht.put(key, category);
	updateParents(category);
	return category;
	} else if(o instanceof Category) {
	return (Category) o;
	} else if (o instanceof ProvisionNode) {
	//System.out.println("("+name+") ht.get(this) returned ProvisionNode");
	category = factory.makeNewCategoryInstance(name);
	category.setHierarchy(this);
	ht.put(key, category);
	updateChildren((ProvisionNode) o, category);
	updateParents(category);
	return category;
	}
	else {
	// It should be impossible to arrive here
	return null; // but let's keep the compiler happy.
	}
	}
	}


	/**
	Returns all the currently defined categories in this hierarchy as
	an {@link java.util.Enumeration Enumeration}.

	<p>The root category is <em>not</em> included in the returned
	{@link Enumeration}. */
	public
	Enumeration getCurrentCategories() {
	// The accumlation in v is necessary because not all elements in
	// ht are Category objects as there might be some ProvisionNodes
	// as well.
	Vector v = new Vector(ht.size());

	Enumeration elems = ht.elements();
	while(elems.hasMoreElements()) {
	Object o = elems.nextElement();
	if(o instanceof Category) {
	v.addElement(o);
	}
	}
	return v.elements();
	}

	/**
	Get the renderer map for this hierarchy.
	*/
	public
	RendererMap getRendererMap() {
	return rendererMap;
	}


	/**
	Get the root of this hierarchy.

	@since 0.9.0
	*/
	public
	Category getRoot() {
	return root;
	}

	/**
	@deprecated See {@link #getEnable} for similar functionality.
	*/

	public
	boolean isDisabled(int level) {
	return enableInt > level;
	}

	/**
	@deprecated Deprecated with no replacement.
	*/
	public
	void overrideAsNeeded(String override) {
	LogLog.warn("The Hiearchy.overrideAsNeeded method has been deprecated.");
	}

	/**
	Reset all values contained in this hierarchy instance to their
	default. This removes all appenders from all categories, sets
	the level of all non-root categories to <code>null</code>,
	sets their additivity flag to <code>true</code> and sets the level
	of the root category to {@link Level#DEBUG DEBUG}. Moreover,
	message disabling is set its default "off" value.

	<p>Existing categories are not removed. They are just reset.

	<p>This method should be used sparingly and with care as it will
	block all logging until it is completed.</p>

	@since 0.8.5 */
	public
	void resetConfiguration() {

	getRoot().setLevel(Level.DEBUG);
	root.setResourceBundle(null);
	enableAll();

	// the synchronization is needed to prevent JDK 1.2.x hashtable
	// surprises
	synchronized(ht) {
	shutdown(); // nested locks are OK

	Enumeration cats = getCurrentCategories();
	while(cats.hasMoreElements()) {
	Category c = (Category) cats.nextElement();
	c.setLevel(null);
	c.setAdditivity(true);
	c.setResourceBundle(null);
	}
	}
	rendererMap.clear();
	}

	/**
	Set the default CategoryFactory instance.

	@since 1.1
	*/
	public void setCategoryFactory(CategoryFactory factory) {
	if (factory != null) {
	defaultFactory = factory;
	}
	}

	/**
	Does mothing.

	@deprecated Deprecated with no replacement.
	*/
	public
	void setDisableOverride(String override) {
	LogLog.warn("The Hiearchy.setDisableOverride method has been deprecated.");
	}

	/**
	Shutting down a hierarchy will <em>safely</em> close and remove
	all appenders in all categories including the root category.

	<p>Some appenders such as {@link org.apache.log4j.net.SocketAppender}
	and {@link AsyncAppender} need to be closed before the
	application exists. Otherwise, pending logging events might be
	lost.

	<p>The <code>shutdown</code> method is careful to close nested
	appenders before closing regular appenders. This is allows
	configurations where a regular appender is attached to a category
	and again to a nested appender.


	@since 1.0 */
	public
	void shutdown() {
	Category root = getRoot();

	// begin by closing nested appenders
	root.closeNestedAppenders();

	synchronized(ht) {
	Enumeration cats = this.getCurrentCategories();
	while(cats.hasMoreElements()) {
	Category c = (Category) cats.nextElement();
	c.closeNestedAppenders();
	}

	// then, remove all appenders
	root.removeAllAppenders();
	cats = this.getCurrentCategories();
	while(cats.hasMoreElements()) {
	Category c = (Category) cats.nextElement();
	c.removeAllAppenders();
	}
	}
	}


	/**
	This method loops through all the potential parents of
	'cat'. There 3 possible cases:

	1) No entry for the potential parent of 'cat' exists

	We create a ProvisionNode for this potential parent and insert
	'cat' in that provision node.

	2) There entry is of type Category for the potential parent.

	The entry is 'cat's nearest existing parent. We update cat's
	parent field with this entry. We also break from the loop
	because updating our parent's parent is our parent's
	responsibility.

	3) There entry is of type ProvisionNode for this potential parent.

	We add 'cat' to the list of children for this potential parent.
	*/
	final
	private
	void updateParents(Category cat) {
	String name = cat.name;
	int length = name.length();
	boolean parentFound = false;

	//System.out.println("UpdateParents called for " + name);

	// if name = "w.x.y.z", loop thourgh "w.x.y", "w.x" and "w", but not "w.x.y.z"
	for(int i = name.lastIndexOf('.', length-1); i >= 0;
	i = name.lastIndexOf('.', i-1)) {
	String substr = name.substring(0, i);

	//System.out.println("Updating parent : " + substr);
	CategoryKey key = new CategoryKey(substr); // simple constructor
	Object o = ht.get(key);
	// Create a provision node for a future parent.
	if(o == null) {
	//System.out.println("No parent "+substr+" found. Creating ProvisionNode.");
	ProvisionNode pn = new ProvisionNode(cat);
	ht.put(key, pn);
	} else if(o instanceof Category) {
	parentFound = true;
	cat.parent = (Category) o;
	//System.out.println("Linking " + cat.name + " -> " + ((Category) o).name);
	break; // no need to update the ancestors of the closest ancestor
	} else if(o instanceof ProvisionNode) {
	((ProvisionNode) o).addElement(cat);
	} else {
	Exception e = new IllegalStateException("unexpected object type " +
	o.getClass() + " in ht.");
	e.printStackTrace();
	}
	}
	// If we could not find any existing parents, then link with root.
	if(!parentFound)
	cat.parent = root;
	}

	/**
	We update the links for all the children that placed themselves
	in the provision node 'pn'. The second argument 'cat' is a
	reference for the newly created Category, parent of all the
	children in 'pn'

	We loop on all the children 'c' in 'pn':

	If the child 'c' has been already linked to a child of
	'cat' then there is no need to update 'c'.

	Otherwise, we set cat's parent field to c's parent and set
	c's parent field to cat.

	*/
	final
	private
	void updateChildren(ProvisionNode pn, Category cat) {
	//System.out.println("updateChildren called for " + cat.name);
	final int last = pn.size();

	for(int i = 0; i < last; i++) {
	Category c = (Category) pn.elementAt(i);
	//System.out.println("Updating child " +p.name);

	// Unless this child already points to a correct (lower) parent,
	// make cat.parent point to c.parent and c.parent to cat.
	if(!c.parent.name.startsWith(cat.name)) {
	cat.parent = c.parent;
	c.parent = cat;
	}
	}
	}

	}