src/Core/LoggerManager.cs

#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you 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.
//
#endregion

using System;
#if NETSTANDARD1_3
using System.Runtime.InteropServices;
#else
using System.Configuration;
#endif
using System.Reflection;

using log4net.Util;
using log4net.Repository;

namespace log4net.Core
{
	/// <summary>
	/// Static manager that controls the creation of repositories
	/// </summary>
	/// <remarks>
	/// <para>
	/// Static manager that controls the creation of repositories
	/// </para>
	/// <para>
	/// This class is used by the wrapper managers (e.g. <see cref="log4net.LogManager"/>)
	/// to provide access to the <see cref="ILogger"/> objects.
	/// </para>
	/// <para>
	/// This manager also holds the <see cref="IRepositorySelector"/> that is used to
	/// lookup and create repositories. The selector can be set either programmatically using
	/// the <see cref="RepositorySelector"/> property, or by setting the <c>log4net.RepositorySelector</c>
	/// AppSetting in the applications config file to the fully qualified type name of the
	/// selector to use. 
	/// </para>
	/// </remarks>
	/// <author>Nicko Cadell</author>
	/// <author>Gert Driesen</author>
	public sealed class LoggerManager
	{
		#region Private Instance Constructors

		/// <summary>
		/// Private constructor to prevent instances. Only static methods should be used.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Private constructor to prevent instances. Only static methods should be used.
		/// </para>
		/// </remarks>
		private LoggerManager() 
		{
		}

		#endregion Private Instance Constructors

		#region Static Constructor

		/// <summary>
		/// Hook the shutdown event
		/// </summary>
		/// <remarks>
		/// <para>
		/// On the full .NET runtime, the static constructor hooks up the 
		/// <c>AppDomain.ProcessExit</c> and <c>AppDomain.DomainUnload</c>> events. 
		/// These are used to shutdown the log4net system as the application exits.
		/// </para>
		/// </remarks>
		static LoggerManager()
		{
			try
			{
				// Register the AppDomain events, note we have to do this with a
				// method call rather than directly here because the AppDomain
				// makes a LinkDemand which throws the exception during the JIT phase.
				RegisterAppDomainEvents();
			}
			catch(System.Security.SecurityException)
			{
				LogLog.Debug(declaringType, "Security Exception (ControlAppDomain LinkDemand) while trying "+
					"to register Shutdown handler with the AppDomain. LoggerManager.Shutdown() "+
					"will not be called automatically when the AppDomain exits. It must be called "+
					"programmatically.");
			}

			// Dump out our assembly version into the log if debug is enabled
            LogLog.Debug(declaringType, GetVersionInfo());

			// Set the default repository selector
#if NETCF
			s_repositorySelector = new CompactRepositorySelector(typeof(log4net.Repository.Hierarchy.Hierarchy));
			return;
#elif !NETSTANDARD1_3
			// Look for the RepositorySelector type specified in the AppSettings 'log4net.RepositorySelector'
			string appRepositorySelectorTypeName = SystemInfo.GetAppSetting("log4net.RepositorySelector");
			if (appRepositorySelectorTypeName != null && appRepositorySelectorTypeName.Length > 0)
			{
				// Resolve the config string into a Type
				Type appRepositorySelectorType = null;
				try
				{
					appRepositorySelectorType = SystemInfo.GetTypeFromString(appRepositorySelectorTypeName, false, true);
				}
				catch(Exception ex)
				{
					LogLog.Error(declaringType, "Exception while resolving RepositorySelector Type ["+appRepositorySelectorTypeName+"]", ex);
				}

				if (appRepositorySelectorType != null)
				{
					// Create an instance of the RepositorySelectorType
					object appRepositorySelectorObj = null;
					try
					{
						appRepositorySelectorObj = Activator.CreateInstance(appRepositorySelectorType);
					}
					catch(Exception ex)
					{
						LogLog.Error(declaringType, "Exception while creating RepositorySelector ["+appRepositorySelectorType.FullName+"]", ex);
					}

					if (appRepositorySelectorObj != null && appRepositorySelectorObj is IRepositorySelector)
					{
						s_repositorySelector = (IRepositorySelector)appRepositorySelectorObj;
					}
					else
					{
						LogLog.Error(declaringType, "RepositorySelector Type ["+appRepositorySelectorType.FullName+"] is not an IRepositorySelector");
					}
				}
			}
#endif
			// Create the DefaultRepositorySelector if not configured above 
			if (s_repositorySelector == null)
			{
				s_repositorySelector = new DefaultRepositorySelector(typeof(log4net.Repository.Hierarchy.Hierarchy));
			}
		}

		/// <summary>
		/// Register for ProcessExit and DomainUnload events on the AppDomain
		/// </summary>
		/// <remarks>
		/// <para>
		/// This needs to be in a separate method because the events make
		/// a LinkDemand for the ControlAppDomain SecurityPermission. Because
		/// this is a LinkDemand it is demanded at JIT time. Therefore we cannot
		/// catch the exception in the method itself, we have to catch it in the
		/// caller.
		/// </para>
		/// </remarks>
		private static void RegisterAppDomainEvents()
		{
#if !(NETCF || NETSTANDARD1_3)
			// ProcessExit seems to be fired if we are part of the default domain
			AppDomain.CurrentDomain.ProcessExit += new EventHandler(OnProcessExit);

			// Otherwise DomainUnload is fired
			AppDomain.CurrentDomain.DomainUnload += new EventHandler(OnDomainUnload);
#endif
		}

		#endregion Static Constructor

		#region Public Static Methods

		/// <summary>
		/// Return the default <see cref="ILoggerRepository"/> instance.
		/// </summary>
		/// <param name="repository">the repository to lookup in</param>
		/// <returns>Return the default <see cref="ILoggerRepository"/> instance</returns>
		/// <remarks>
		/// <para>
		/// Gets the <see cref="ILoggerRepository"/> for the repository specified
		/// by the <paramref name="repository"/> argument.
		/// </para>
		/// </remarks>
		[Obsolete("Use GetRepository instead of GetLoggerRepository")]
		public static ILoggerRepository GetLoggerRepository(string repository)
		{
			return GetRepository(repository);
		}

		/// <summary>
		/// Returns the default <see cref="ILoggerRepository"/> instance.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
		/// <returns>The default <see cref="ILoggerRepository"/> instance.</returns>
		[Obsolete("Use GetRepository instead of GetLoggerRepository")]
		public static ILoggerRepository GetLoggerRepository(Assembly repositoryAssembly)
		{
			return GetRepository(repositoryAssembly);
		}

		/// <summary>
		/// Return the default <see cref="ILoggerRepository"/> instance.
		/// </summary>
		/// <param name="repository">the repository to lookup in</param>
		/// <returns>Return the default <see cref="ILoggerRepository"/> instance</returns>
		/// <remarks>
		/// <para>
		/// Gets the <see cref="ILoggerRepository"/> for the repository specified
		/// by the <paramref name="repository"/> argument.
		/// </para>
		/// </remarks>
		public static ILoggerRepository GetRepository(string repository)
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			return RepositorySelector.GetRepository(repository);
		}

		/// <summary>
		/// Returns the default <see cref="ILoggerRepository"/> instance.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
		/// <returns>The default <see cref="ILoggerRepository"/> instance.</returns>
		/// <remarks>
		/// <para>
		/// Returns the default <see cref="ILoggerRepository"/> instance.
		/// </para>
		/// </remarks>
		public static ILoggerRepository GetRepository(Assembly repositoryAssembly)
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			return RepositorySelector.GetRepository(repositoryAssembly);
		}

		/// <summary>
		/// Returns the named logger if it exists.
		/// </summary>
		/// <param name="repository">The repository to lookup in.</param>
		/// <param name="name">The fully qualified logger name to look for.</param>
		/// <returns>
		/// The logger found, or <c>null</c> if the named logger does not exist in the
		/// specified repository.
		/// </returns>
		/// <remarks>
		/// <para>
		/// If the named logger exists (in the specified repository) then it
		/// returns a reference to the logger, otherwise it returns
		/// <c>null</c>.
		/// </para>
		/// </remarks>
		public static ILogger Exists(string repository, string name) 
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}
			return RepositorySelector.GetRepository(repository).Exists(name);
		}

		/// <summary>
		/// Returns the named logger if it exists.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
		/// <param name="name">The fully qualified logger name to look for.</param>
		/// <returns>
		/// The logger found, or <c>null</c> if the named logger does not exist in the
		/// specified assembly's repository.
		/// </returns>
		/// <remarks>
		/// <para>
		/// If the named logger exists (in the specified assembly's repository) then it
		/// returns a reference to the logger, otherwise it returns
		/// <c>null</c>.
		/// </para>
		/// </remarks>
		public static ILogger Exists(Assembly repositoryAssembly, string name) 
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}
			return RepositorySelector.GetRepository(repositoryAssembly).Exists(name);
		}

		/// <summary>
		/// Returns all the currently defined loggers in the specified repository.
		/// </summary>
		/// <param name="repository">The repository to lookup in.</param>
		/// <returns>All the defined loggers.</returns>
		/// <remarks>
		/// <para>
		/// The root logger is <b>not</b> included in the returned array.
		/// </para>
		/// </remarks>
		public static ILogger[] GetCurrentLoggers(string repository)
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			return RepositorySelector.GetRepository(repository).GetCurrentLoggers();
		}

		/// <summary>
		/// Returns all the currently defined loggers in the specified assembly's repository.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
		/// <returns>All the defined loggers.</returns>
		/// <remarks>
		/// <para>
		/// The root logger is <b>not</b> included in the returned array.
		/// </para>
		/// </remarks>
		public static ILogger[] GetCurrentLoggers(Assembly repositoryAssembly)
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			return RepositorySelector.GetRepository(repositoryAssembly).GetCurrentLoggers();
		}

		/// <summary>
		/// Retrieves or creates a named logger.
		/// </summary>
		/// <param name="repository">The repository to lookup in.</param>
		/// <param name="name">The name of the logger to retrieve.</param>
		/// <returns>The logger with the name specified.</returns>
		/// <remarks>
		/// <para>
		/// Retrieves a logger named as the <paramref name="name"/>
		/// parameter. If the named logger already exists, then the
		/// existing instance will be returned. Otherwise, a new instance is
		/// created.
		/// </para>
		/// <para>
		/// By default, loggers do not have a set level but inherit
		/// it from the hierarchy. This is one of the central features of
		/// log4net.
		/// </para>
		/// </remarks>
		public static ILogger GetLogger(string repository, string name)
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}
			return RepositorySelector.GetRepository(repository).GetLogger(name);
		}

		/// <summary>
		/// Retrieves or creates a named logger.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
		/// <param name="name">The name of the logger to retrieve.</param>
		/// <returns>The logger with the name specified.</returns>
		/// <remarks>
		/// <para>
		/// Retrieves a logger named as the <paramref name="name"/>
		/// parameter. If the named logger already exists, then the
		/// existing instance will be returned. Otherwise, a new instance is
		/// created.
		/// </para>
		/// <para>
		/// By default, loggers do not have a set level but inherit
		/// it from the hierarchy. This is one of the central features of
		/// log4net.
		/// </para>
		/// </remarks>
		public static ILogger GetLogger(Assembly repositoryAssembly, string name)
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			if (name == null)
			{
				throw new ArgumentNullException("name");
			}
			return RepositorySelector.GetRepository(repositoryAssembly).GetLogger(name);
		}	

		/// <summary>
		/// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
		/// </summary>
		/// <param name="repository">The repository to lookup in.</param>
		/// <param name="type">The <paramref name="type"/> of which the fullname will be used as the name of the logger to retrieve.</param>
		/// <returns>The logger with the name specified.</returns>
		/// <remarks>
		/// <para>
		/// Gets the logger for the fully qualified name of the type specified.
		/// </para>
		/// </remarks>
		public static ILogger GetLogger(string repository, Type type) 
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			if (type == null)
			{
				throw new ArgumentNullException("type");
			}
			return RepositorySelector.GetRepository(repository).GetLogger(type.FullName);
		}

		/// <summary>
		/// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
		/// </summary>
		/// <param name="repositoryAssembly">the assembly to use to lookup the repository</param>
		/// <param name="type">The <paramref name="type"/> of which the fullname will be used as the name of the logger to retrieve.</param>
		/// <returns>The logger with the name specified.</returns>
		/// <remarks>
		/// <para>
		/// Gets the logger for the fully qualified name of the type specified.
		/// </para>
		/// </remarks>
		public static ILogger GetLogger(Assembly repositoryAssembly, Type type) 
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			if (type == null)
			{
				throw new ArgumentNullException("type");
			}
			return RepositorySelector.GetRepository(repositoryAssembly).GetLogger(type.FullName);
		}	

		/// <summary>
		/// Shuts down the log4net system.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Calling this method will <b>safely</b> close and remove all
		/// appenders in all the loggers including root contained in all the
		/// default repositories.
		/// </para>
		/// <para>
		/// Some appenders need to be closed before the application exists. 
		/// Otherwise, pending logging events might be lost.
		/// </para>
		/// <para>
		/// The <c>shutdown</c> method is careful to close nested
		/// appenders before closing regular appenders. This is allows
		/// configurations where a regular appender is attached to a logger
		/// and again to a nested appender.
		/// </para>
		/// </remarks>
		public static void Shutdown() 
		{
			foreach(ILoggerRepository repository in GetAllRepositories())
			{
				repository.Shutdown();
			}
		}

		/// <summary>
		/// Shuts down the repository for the repository specified.
		/// </summary>
		/// <param name="repository">The repository to shutdown.</param>
		/// <remarks>
		/// <para>
		/// Calling this method will <b>safely</b> close and remove all
		/// appenders in all the loggers including root contained in the
		/// repository for the <paramref name="repository"/> specified.
		/// </para>
		/// <para>
		/// Some appenders need to be closed before the application exists. 
		/// Otherwise, pending logging events might be lost.
		/// </para>
		/// <para>
		/// The <c>shutdown</c> method is careful to close nested
		/// appenders before closing regular appenders. This is allows
		/// configurations where a regular appender is attached to a logger
		/// and again to a nested appender.
		/// </para>
		/// </remarks>
		public static void ShutdownRepository(string repository) 
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			RepositorySelector.GetRepository(repository).Shutdown();
		}

		/// <summary>
		/// Shuts down the repository for the repository specified.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
		/// <remarks>
		/// <para>
		/// Calling this method will <b>safely</b> close and remove all
		/// appenders in all the loggers including root contained in the
		/// repository for the repository. The repository is looked up using
		/// the <paramref name="repositoryAssembly"/> specified.
		/// </para>
		/// <para>
		/// Some appenders need to be closed before the application exists. 
		/// Otherwise, pending logging events might be lost.
		/// </para>
		/// <para>
		/// The <c>shutdown</c> method is careful to close nested
		/// appenders before closing regular appenders. This is allows
		/// configurations where a regular appender is attached to a logger
		/// and again to a nested appender.
		/// </para>
		/// </remarks>
		public static void ShutdownRepository(Assembly repositoryAssembly) 
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			RepositorySelector.GetRepository(repositoryAssembly).Shutdown();
		}

		/// <summary>
		/// Resets all values contained in this repository instance to their defaults.
		/// </summary>
		/// <param name="repository">The repository to reset.</param>
		/// <remarks>
		/// <para>
		/// Resets all values contained in the repository instance to their
		/// defaults.  This removes all appenders from all loggers, sets
		/// the level of all non-root loggers to <c>null</c>,
		/// sets their additivity flag to <c>true</c> and sets the level
		/// of the root logger to <see cref="Level.Debug"/>. Moreover,
		/// message disabling is set its default "off" value.
		/// </para>		
		/// </remarks>
		public static void ResetConfiguration(string repository) 
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			RepositorySelector.GetRepository(repository).ResetConfiguration();
		}

		/// <summary>
		/// Resets all values contained in this repository instance to their defaults.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to lookup the repository to reset.</param>
		/// <remarks>
		/// <para>
		/// Resets all values contained in the repository instance to their
		/// defaults.  This removes all appenders from all loggers, sets
		/// the level of all non-root loggers to <c>null</c>,
		/// sets their additivity flag to <c>true</c> and sets the level
		/// of the root logger to <see cref="Level.Debug"/>. Moreover,
		/// message disabling is set its default "off" value.
		/// </para>		
		/// </remarks>
		public static void ResetConfiguration(Assembly repositoryAssembly) 
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			RepositorySelector.GetRepository(repositoryAssembly).ResetConfiguration();
		}

		/// <summary>
		/// Creates a repository with the specified name.
		/// </summary>
		/// <param name="repository">The name of the repository, this must be unique amongst repositories.</param>
		/// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
		/// <remarks>
		/// <para>
		/// <b>CreateDomain is obsolete. Use CreateRepository instead of CreateDomain.</b>
		/// </para>
		/// <para>
		/// Creates the default type of <see cref="ILoggerRepository"/> which is a
		/// <see cref="log4net.Repository.Hierarchy.Hierarchy"/> object.
		/// </para>
		/// <para>
		/// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
		/// An <see cref="Exception"/> will be thrown if the repository already exists.
		/// </para>
		/// </remarks>
		/// <exception cref="LogException">The specified repository already exists.</exception>
		[Obsolete("Use CreateRepository instead of CreateDomain")]
		public static ILoggerRepository CreateDomain(string repository)
		{
			return CreateRepository(repository);
		}

		/// <summary>
		/// Creates a repository with the specified name.
		/// </summary>
		/// <param name="repository">The name of the repository, this must be unique amongst repositories.</param>
		/// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
		/// <remarks>
		/// <para>
		/// Creates the default type of <see cref="ILoggerRepository"/> which is a
		/// <see cref="log4net.Repository.Hierarchy.Hierarchy"/> object.
		/// </para>
		/// <para>
		/// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
		/// An <see cref="Exception"/> will be thrown if the repository already exists.
		/// </para>
		/// </remarks>
		/// <exception cref="LogException">The specified repository already exists.</exception>
		public static ILoggerRepository CreateRepository(string repository)
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			return RepositorySelector.CreateRepository(repository, null);
		}

		/// <summary>
		/// Creates a repository with the specified name and repository type.
		/// </summary>
		/// <param name="repository">The name of the repository, this must be unique to the repository.</param>
		/// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
		/// and has a no arg constructor. An instance of this type will be created to act
		/// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
		/// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
		/// <remarks>
		/// <para>
		/// <b>CreateDomain is obsolete. Use CreateRepository instead of CreateDomain.</b>
		/// </para>
		/// <para>
		/// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
		/// An Exception will be thrown if the repository already exists.
		/// </para>
		/// </remarks>
		/// <exception cref="LogException">The specified repository already exists.</exception>
		[Obsolete("Use CreateRepository instead of CreateDomain")]
		public static ILoggerRepository CreateDomain(string repository, Type repositoryType)
		{
			return CreateRepository(repository, repositoryType);
		}

		/// <summary>
		/// Creates a repository with the specified name and repository type.
		/// </summary>
		/// <param name="repository">The name of the repository, this must be unique to the repository.</param>
		/// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
		/// and has a no arg constructor. An instance of this type will be created to act
		/// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
		/// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
		/// <remarks>
		/// <para>
		/// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
		/// An Exception will be thrown if the repository already exists.
		/// </para>
		/// </remarks>
		/// <exception cref="LogException">The specified repository already exists.</exception>
		public static ILoggerRepository CreateRepository(string repository, Type repositoryType)
		{
			if (repository == null)
			{
				throw new ArgumentNullException("repository");
			}
			if (repositoryType == null)
			{
				throw new ArgumentNullException("repositoryType");
			}
			return RepositorySelector.CreateRepository(repository, repositoryType);
		}

		/// <summary>
		/// Creates a repository for the specified assembly and repository type.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to get the name of the repository.</param>
		/// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
		/// and has a no arg constructor. An instance of this type will be created to act
		/// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
		/// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
		/// <remarks>
		/// <para>
		/// <b>CreateDomain is obsolete. Use CreateRepository instead of CreateDomain.</b>
		/// </para>
		/// <para>
		/// The <see cref="ILoggerRepository"/> created will be associated with the repository
		/// specified such that a call to <see cref="M:GetRepository(Assembly)"/> with the
		/// same assembly specified will return the same repository instance.
		/// </para>
		/// </remarks>
		[Obsolete("Use CreateRepository instead of CreateDomain")]
		public static ILoggerRepository CreateDomain(Assembly repositoryAssembly, Type repositoryType)
		{
			return CreateRepository(repositoryAssembly, repositoryType);
		}

		/// <summary>
		/// Creates a repository for the specified assembly and repository type.
		/// </summary>
		/// <param name="repositoryAssembly">The assembly to use to get the name of the repository.</param>
		/// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
		/// and has a no arg constructor. An instance of this type will be created to act
		/// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
		/// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
		/// <remarks>
		/// <para>
		/// The <see cref="ILoggerRepository"/> created will be associated with the repository
		/// specified such that a call to <see cref="M:GetRepository(Assembly)"/> with the
		/// same assembly specified will return the same repository instance.
		/// </para>
		/// </remarks>
		public static ILoggerRepository CreateRepository(Assembly repositoryAssembly, Type repositoryType)
		{
			if (repositoryAssembly == null)
			{
				throw new ArgumentNullException("repositoryAssembly");
			}
			if (repositoryType == null)
			{
				throw new ArgumentNullException("repositoryType");
			}
			return RepositorySelector.CreateRepository(repositoryAssembly, repositoryType);
		}

		/// <summary>
		/// Gets an array of all currently defined repositories.
		/// </summary>
		/// <returns>An array of all the known <see cref="ILoggerRepository"/> objects.</returns>
		/// <remarks>
		/// <para>
		/// Gets an array of all currently defined repositories.
		/// </para>
		/// </remarks>
		public static ILoggerRepository[] GetAllRepositories()
		{
			return RepositorySelector.GetAllRepositories();
		}

		/// <summary>
		/// Gets or sets the repository selector used by the <see cref="LogManager" />.
		/// </summary>
		/// <value>
		/// The repository selector used by the <see cref="LogManager" />.
		/// </value>
		/// <remarks>
		/// <para>
		/// The repository selector (<see cref="IRepositorySelector"/>) is used by 
		/// the <see cref="LogManager"/> to create and select repositories 
		/// (<see cref="ILoggerRepository"/>).
		/// </para>
		/// <para>
		/// The caller to <see cref="LogManager"/> supplies either a string name 
		/// or an assembly (if not supplied the assembly is inferred using 
		/// <see cref="M:Assembly.GetCallingAssembly()"/>).
		/// </para>
		/// <para>
		/// This context is used by the selector to lookup a specific repository.
		/// </para>
		/// <para>
		/// For the full .NET Framework, the default repository is <c>DefaultRepositorySelector</c>;
		/// for the .NET Compact Framework <c>CompactRepositorySelector</c> is the default
		/// repository.
		/// </para>
		/// </remarks>
		public static IRepositorySelector RepositorySelector
		{
			get { return s_repositorySelector; }
			set { s_repositorySelector = value; }
		}

		#endregion Public Static Methods

		#region Private Static Methods

		/// <summary>
		/// Internal method to get pertinent version info.
		/// </summary>
		/// <returns>A string of version info.</returns>
		private static string GetVersionInfo()
		{
			System.Text.StringBuilder sb = new System.Text.StringBuilder();

#if NETSTANDARD1_3
			Assembly myAssembly = typeof(LoggerManager).GetTypeInfo().Assembly;
			sb.Append($"log4net assembly [{myAssembly.FullName}]. ");
			//sb.Append($"Loaded from [{myAssembly.Location}]. "); // TODO Assembly.Location available in netstandard1.5
			sb.Append($"(.NET Framework [{RuntimeInformation.FrameworkDescription}] on {RuntimeInformation.OSDescription}");
#else
			Assembly myAssembly = Assembly.GetExecutingAssembly();
			sb.Append("log4net assembly [").Append(myAssembly.FullName).Append("]. ");
			sb.Append("Loaded from [").Append(SystemInfo.AssemblyLocationInfo(myAssembly)).Append("]. ");
			sb.Append("(.NET Runtime [").Append(Environment.Version.ToString()).Append("]");
#if (!SSCLI)
            sb.Append(" on ").Append(Environment.OSVersion.ToString());
#endif
#endif // NETSTANDARD1_3
			sb.Append(")");
			return sb.ToString();
		}

#if (!NETCF)
		/// <summary>
		/// Called when the <see cref="AppDomain.DomainUnload"/> event fires
		/// </summary>
		/// <param name="sender">the <see cref="AppDomain"/> that is exiting</param>
		/// <param name="e">null</param>
		/// <remarks>
		/// <para>
		/// Called when the <see cref="AppDomain.DomainUnload"/> event fires.
		/// </para>
		/// <para>
		/// When the event is triggered the log4net system is <see cref="M:Shutdown()"/>.
		/// </para>
		/// </remarks>
		private static void OnDomainUnload(object sender, EventArgs e)
		{
			Shutdown();
		}

		/// <summary>
		/// Called when the <see cref="AppDomain.ProcessExit"/> event fires
		/// </summary>
		/// <param name="sender">the <see cref="AppDomain"/> that is exiting</param>
		/// <param name="e">null</param>
		/// <remarks>
		/// <para>
		/// Called when the <see cref="AppDomain.ProcessExit"/> event fires.
		/// </para>
		/// <para>
		/// When the event is triggered the log4net system is <see cref="M:Shutdown()"/>.
		/// </para>
		/// </remarks>
		private static void OnProcessExit(object sender, EventArgs e)
		{
			Shutdown();
		}
#endif

		#endregion Private Static Methods

		#region Private Static Fields

	    /// <summary>
	    /// The fully qualified type of the LoggerManager class.
	    /// </summary>
	    /// <remarks>
	    /// Used by the internal logger to record the Type of the
	    /// log message.
	    /// </remarks>
	    private readonly static Type declaringType = typeof(LoggerManager);

		/// <summary>
		/// Initialize the default repository selector
		/// </summary>
		private static IRepositorySelector s_repositorySelector;

		#endregion Private Static Fields
	}
}