hierarchy.cs

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		#endregion Override Implementation of LoggerRepositorySkeleton

		/// <summary>
		/// Collect the appenders from an <see cref="IAppenderAttachable"/>.
		/// The appender may also be a container.
		/// </summary>
		/// <param name="appenderList"></param>
		/// <param name="appender"></param>
		private static void CollectAppender(System.Collections.ArrayList appenderList, log4net.Appender.IAppender appender)
		{
			if (!appenderList.Contains(appender))
			{
				appenderList.Add(appender);

				IAppenderAttachable container = appender as IAppenderAttachable;
				if (container != null)
				{
					CollectAppenders(appenderList, container);
				}
			}
		}

		/// <summary>
		/// Collect the appenders from an <see cref="IAppenderAttachable"/> container
		/// </summary>
		/// <param name="appenderList"></param>
		/// <param name="container"></param>
		private static void CollectAppenders(System.Collections.ArrayList appenderList, IAppenderAttachable container)
		{
			foreach(log4net.Appender.IAppender appender in container.Appenders)
			{
				CollectAppender(appenderList, appender);
			}
		}

		#region Implementation of IBasicRepositoryConfigurator

		/// <summary>
		/// Initialize the log4net system using the specified appender
		/// </summary>
		/// <param name="appender">the appender to use to log all logging events</param>
		void IBasicRepositoryConfigurator.Configure(log4net.Appender.IAppender appender)
		{
			BasicRepositoryConfigure(appender);
		}

		/// <summary>
		/// Initialize the log4net system using the specified appender
		/// </summary>
		/// <param name="appender">the appender to use to log all logging events</param>
		/// <remarks>
		/// <para>
		/// This method provides the same functionality as the 
		/// <see cref="IBasicRepositoryConfigurator.Configure"/> method implemented
		/// on this object, but it is protected and therefore can be called by subclasses.
		/// </para>
		/// </remarks>
		protected void BasicRepositoryConfigure(log4net.Appender.IAppender appender)
		{
			Root.AddAppender(appender);

			Configured = true;

			// Notify listeners
			OnConfigurationChanged(null);
		}

		#endregion Implementation of IBasicRepositoryConfigurator

		#region Implementation of IXmlRepositoryConfigurator

		/// <summary>
		/// Initialize the log4net system using the specified config
		/// </summary>
		/// <param name="element">the element containing the root of the config</param>
		void IXmlRepositoryConfigurator.Configure(System.Xml.XmlElement element)
		{
			XmlRepositoryConfigure(element);
		}

		/// <summary>
		/// Initialize the log4net system using the specified config
		/// </summary>
		/// <param name="element">the element containing the root of the config</param>
		/// <remarks>
		/// <para>
		/// This method provides the same functionality as the 
		/// <see cref="IBasicRepositoryConfigurator.Configure"/> method implemented
		/// on this object, but it is protected and therefore can be called by subclasses.
		/// </para>
		/// </remarks>
		protected void XmlRepositoryConfigure(System.Xml.XmlElement element)
		{
			XmlHierarchyConfigurator config = new XmlHierarchyConfigurator(this);
			config.Configure(element);

			Configured = true;

			// Notify listeners
			OnConfigurationChanged(null);
		}

		#endregion Implementation of IXmlRepositoryConfigurator

		#region Public Instance Methods

		/// <summary>
		/// Test if this hierarchy is disabled for the specified <see cref="Level"/>.
		/// </summary>
		/// <param name="level">The level to check against.</param>
		/// <returns>
		/// <c>true</c> if the repository is disabled for the level argument, <c>false</c> otherwise.
		/// </returns>
		/// <remarks>
		/// <para>
		/// If this hierarchy has not been configured then this method will
		/// always return <c>true</c>.
		/// </para>
		/// <para>
		/// This method will return <c>true</c> if this repository is
		/// disabled for <c>level</c> object passed as parameter and
		/// <c>false</c> otherwise.
		/// </para>
		/// <para>
		/// See also the <see cref="ILoggerRepository.Threshold"/> property.
		/// </para>
		/// </remarks>
		public bool IsDisabled(Level level) 
		{
			// Cast level to object for performance
			if ((object)level == null)
			{
				throw new ArgumentNullException("level");
			}

			if (Configured)
			{
				return Threshold > level;
			}
			else
			{
				// If not configured the hierarchy is effectively disabled
				return true;
			}
		}

		/// <summary>
		/// Clear all logger definitions from the internal hashtable
		/// </summary>
		/// <remarks>
		/// <para>
		/// This call will clear all logger definitions from the internal
		/// hashtable. Invoking this method will irrevocably mess up the
		/// logger hierarchy.
		/// </para>
		/// <para>
		/// You should <b>really</b> know what you are doing before
		/// invoking this method.
		/// </para>
		/// </remarks>
		public void Clear() 
		{
			m_ht.Clear();
		}

		/// <summary>
		/// Return a new logger instance named as the first parameter using
		/// <paramref name="factory"/>.
		/// </summary>
		/// <param name="name">The name of the logger to retrieve</param>
		/// <param name="factory">The factory that will make the new logger instance</param>
		/// <returns>The logger object with the name specified</returns>
		/// <remarks>
		/// <para>
		/// If a logger of that name already exists, then it will be
		/// returned. Otherwise, a new logger will be instantiated by the
		/// <paramref name="factory"/> parameter and linked with its existing
		/// ancestors as well as children.
		/// </para>
		/// </remarks>
		public Logger GetLogger(string name, ILoggerFactory factory) 
		{
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}
			if (factory == null)
			{
				throw new ArgumentNullException("factory");
			}

			LoggerKey key = new LoggerKey(name);   
 
			// Synchronize to prevent write conflicts. Read conflicts (in
			// GetEffectiveLevel() method) are possible only if variable
			// assignments are non-atomic.
			Logger logger;
	
			lock(m_ht) 
			{
				Object node = m_ht[key];
				if (node == null) 
				{
					logger = factory.CreateLogger(name);
					logger.Hierarchy = this;
					m_ht[key] = logger;	  
					UpdateParents(logger);
					OnLoggerCreationEvent(logger);
					return logger;
				} 
				
				Logger nodeLogger = node as Logger;
				if (nodeLogger != null) 
				{
					return nodeLogger;
				} 
				
				ProvisionNode nodeProvisionNode = node as ProvisionNode;
				if (nodeProvisionNode != null) 
				{
					logger = factory.CreateLogger(name);
					logger.Hierarchy = this; 
					m_ht[key] = logger;
					UpdateChildren(nodeProvisionNode, logger);
					UpdateParents(logger);	
					OnLoggerCreationEvent(logger);
					return logger;
				}

				// It should be impossible to arrive here but let's keep the compiler happy.
				return null;
			}
		}

		#endregion Public Instance Methods

		#region Protected Instance Methods

		/// <summary>
		/// Sends a logger creation event to all registered listeners
		/// </summary>
		/// <param name="logger">The newly created logger</param>
		/// <remarks>
		/// Raises the logger creation event.
		/// </remarks>
		protected virtual void OnLoggerCreationEvent(Logger logger) 
		{
			LoggerCreationEventHandler handler = m_loggerCreatedEvent;
			if (handler != null)
			{
				handler(this, new LoggerCreationEventArgs(logger));
			}
		}

		#endregion Protected Instance Methods

		#region Private Instance Methods

		/// <summary>
		/// Updates all the parents of the specified logger
		/// </summary>
		/// <param name="log">The logger to update the parents for</param>
		/// <remarks>
		/// <para>
		/// This method loops through all the <i>potential</i> parents of
		/// <paramref name="log"/>. There 3 possible cases:
		/// </para>
		/// <list type="number">
		///		<item>
		///			<term>No entry for the potential parent of <paramref name="log"/> exists</term>
		///			<description>
		///			We create a ProvisionNode for this potential 
		///			parent and insert <paramref name="log"/> in that provision node.
		///			</description>
		///		</item>
		///		<item>
		///			<term>The entry is of type Logger for the potential parent.</term>
		///			<description>
		///			The entry is <paramref name="log"/>'s nearest existing parent. We 
		///			update <paramref name="log"/>'s parent field with this entry. We also break from 
		///			he loop because updating our parent's parent is our parent's 
		///			responsibility.
		///			</description>
		///		</item>
		///		<item>
		///			<term>The entry is of type ProvisionNode for this potential parent.</term>
		///			<description>
		///			We add <paramref name="log"/> to the list of children for this 
		///			potential parent.
		///			</description>
		///		</item>
		/// </list>
		/// </remarks>
		private void UpdateParents(Logger log) 
		{
			string name = log.Name;
			int length = name.Length;
			bool parentFound = false;
	
			// if name = "w.x.y.z", loop through "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);

				LoggerKey key = new LoggerKey(substr); // simple constructor
				Object node = m_ht[key];
				// Create a provision node for a future parent.
				if (node == null) 
				{
					ProvisionNode pn = new ProvisionNode(log);
					m_ht[key] = pn;
				} 
				else
				{
					Logger nodeLogger = node as Logger;
					if (nodeLogger != null)
					{
						parentFound = true;
						log.Parent = nodeLogger;
						break; // no need to update the ancestors of the closest ancestor
					}
					else
					{
						ProvisionNode nodeProvisionNode = node as ProvisionNode;
						if (nodeProvisionNode != null)
						{
							nodeProvisionNode.Add(log);
						}
						else
						{
							LogLog.Error("Hierarchy: Unexpected object type ["+node.GetType()+"] in ht.", new LogException());
						}
					} 
				} 
			}

			// If we could not find any existing parents, then link with root.
			if (!parentFound) 
			{
				log.Parent = this.Root;
			}
		}

		/// <summary>
		/// Replace a <see cref="ProvisionNode"/> with a <see cref="Logger"/> in the hierarchy.
		/// </summary>
		/// <param name="pn"></param>
		/// <param name="log"></param>
		/// <remarks>
		/// <para>
		/// We update the links for all the children that placed themselves
		/// in the provision node 'pn'. The second argument 'log' is a
		/// reference for the newly created Logger, parent of all the
		/// children in 'pn'.
		/// </para>
		/// <para>
		/// We loop on all the children 'c' in 'pn'.
		/// </para>
		/// <para>
		/// If the child 'c' has been already linked to a child of
		/// 'log' then there is no need to update 'c'.
		/// </para>
		/// <para>
		/// Otherwise, we set log's parent field to c's parent and set
		/// c's parent field to log.
		/// </para>
		/// </remarks>
		private void UpdateChildren(ProvisionNode pn, Logger log) 
		{
			for(int i = 0; i < pn.Count; i++) 
			{
				Logger childLogger = (Logger)pn[i];

				// Unless this child already points to a correct (lower) parent,
				// make log.Parent point to childLogger.Parent and childLogger.Parent to log.
				if (!childLogger.Parent.Name.StartsWith(log.Name)) 
				{
					log.Parent = childLogger.Parent;
					childLogger.Parent = log;	  
				}
			}
		}

		/// <summary>
		/// Define or redefine a Level using the values in the <see cref="LevelEntry"/> argument
		/// </summary>
		/// <param name="levelEntry">the level values</param>
		/// <remarks>
		/// <para>
		/// Define or redefine a Level using the values in the <see cref="LevelEntry"/> argument
		/// </para>
		/// </remarks>
		internal void AddLevel(LevelEntry levelEntry)
		{
			if (levelEntry == null) throw new ArgumentNullException("levelEntry");
			if (levelEntry.Name == null) throw new ArgumentNullException("levelEntry.Name");

			// Lookup replacement value
			if (levelEntry.Value == -1)
			{
				Level previousLevel = LevelMap[levelEntry.Name];
				if (previousLevel == null)
				{
					throw new InvalidOperationException("Cannot redefine level ["+levelEntry.Name+"] because it is not defined in the LevelMap. To define the level supply the level value.");
				}

				levelEntry.Value = previousLevel.Value;
			}

			LevelMap.Add(levelEntry.Name, levelEntry.Value, levelEntry.DisplayName);
		}

		/// <summary>
		/// A class to hold the value, name and display name for a logging event
		/// </summary>
		/// <remarks>
		/// <para>
		/// A class to hold the value, name and display name for a logging event
		/// </para>
		/// </remarks>
		internal class LevelEntry
		{
			private int m_levelValue = -1;
			private string m_levelName = null;
			private string m_levelDisplayName = null;

			/// <summary>
			/// Value of the level
			/// </summary>
			/// <remarks>
			/// <para>
			/// If the value is not set (defaults to -1) the value will be looked
			/// up for the current level with the same name.
			/// </para>
			/// </remarks>
			public int Value
			{
				get { return m_levelValue; }
				set { m_levelValue = value; }
			}

			/// <summary>
			/// Name of the level
			/// </summary>
			/// <value>
			/// The name of the level
			/// </value>
			/// <remarks>
			/// <para>
			/// The name of the level.
			/// </para>
			/// </remarks>
			public string Name
			{
				get { return m_levelName; }
				set { m_levelName = value; }
			}

			/// <summary>
			/// Display name for the level
			/// </summary>
			/// <value>
			/// The display name of the level
			/// </value>
			/// <remarks>
			/// <para>
			/// The display name of the level.
			/// </para>
			/// </remarks>
			public string DisplayName
			{
				get { return m_levelDisplayName; }
				set { m_levelDisplayName = value; }
			}

			/// <summary>
			/// Override <c>Object.ToString</c> to return sensible debug info
			/// </summary>
			/// <returns>string info about this object</returns>
			public override string ToString()
			{
				return "LevelEntry(Value="+m_levelValue+", Name="+m_levelName+", DisplayName="+m_levelDisplayName+")";
			}
		}

		#endregion Private Instance Methods

		#region Private Instance Fields

		private ILoggerFactory m_defaultFactory;

		private System.Collections.Hashtable m_ht;
		private Logger m_root;
  
		private bool m_emittedNoAppenderWarning = false;
		private event LoggerCreationEventHandler m_loggerCreatedEvent;

		#endregion Private Instance Fields
	}
}