rollingfileappender.cs

精通SQL Server2005项目开发

		/// </para>
		/// <para>
		/// When set to <see cref="RollingMode.Once"/> this appender's
		/// <see cref="FileAppender.AppendToFile"/> property is set to <c>false</c>, otherwise
		/// the appender would append to a single file rather than rolling
		/// the file each time it is opened.
		/// </para>
		/// </remarks>
		public RollingMode RollingStyle
		{
			get { return m_rollingStyle; }
			set
			{
				m_rollingStyle = value;
				switch (m_rollingStyle) 
				{
					case RollingMode.Once:
						m_rollDate = false;
						m_rollSize = false;

						this.AppendToFile = false;
						break;

					case RollingMode.Size:
						m_rollDate = false;
						m_rollSize = true;
						break;

					case RollingMode.Date:
						m_rollDate = true;
						m_rollSize = false;
						break;

					case RollingMode.Composite:
						m_rollDate = true;
						m_rollSize = true;
						break;	  
				}
			}
		}
  
		/// <summary>
		/// Gets or sets a value indicating whether to always log to
		/// the same file.
		/// </summary>
		/// <value>
		/// <c>true</c> if always should be logged to the same file, otherwise <c>false</c>.
		/// </value>
		/// <remarks>
		/// <para>
		/// By default file.log is always the current file.  Optionally
		/// file.log.yyyy-mm-dd for current formatted datePattern can by the currently
		/// logging file (or file.log.curSizeRollBackup or even
		/// file.log.yyyy-mm-dd.curSizeRollBackup).
		/// </para>
		/// <para>
		/// This will make time based rollovers with a large number of backups 
		/// much faster as the appender it won't have to rename all the backups!
		/// </para>
		/// </remarks>
		public bool StaticLogFileName
		{
			get { return m_staticLogFileName; }
			set { m_staticLogFileName = value; }
		}

		#endregion Public Instance Properties

		#region Override implementation of FileAppender 
  
		/// <summary>
		/// Sets the quiet writer being used.
		/// </summary>
		/// <remarks>
		/// This method can be overridden by sub classes.
		/// </remarks>
		/// <param name="writer">the writer to set</param>
		override protected void SetQWForFiles(TextWriter writer) 
		{
			QuietWriter = new CountingQuietTextWriter(writer, ErrorHandler);
		}

		/// <summary>
		/// Write out a logging event.
		/// </summary>
		/// <param name="loggingEvent">the event to write to file.</param>
		/// <remarks>
		/// <para>
		/// Handles append time behavior for RollingFileAppender.  This checks
		/// if a roll over either by date (checked first) or time (checked second)
		/// is need and then appends to the file last.
		/// </para>
		/// </remarks>
		override protected void Append(LoggingEvent loggingEvent) 
		{
			AdjustFileBeforeAppend();
			base.Append(loggingEvent);
		}
  
 		/// <summary>
		/// Write out an array of logging events.
		/// </summary>
		/// <param name="loggingEvents">the events to write to file.</param>
		/// <remarks>
		/// <para>
		/// Handles append time behavior for RollingFileAppender.  This checks
		/// if a roll over either by date (checked first) or time (checked second)
		/// is need and then appends to the file last.
		/// </para>
		/// </remarks>
		override protected void Append(LoggingEvent[] loggingEvents) 
		{
			AdjustFileBeforeAppend();
			base.Append(loggingEvents);
		}

		/// <summary>
		/// Performs any required rolling before outputting the next event
		/// </summary>
		/// <remarks>
		/// <para>
		/// Handles append time behavior for RollingFileAppender.  This checks
		/// if a roll over either by date (checked first) or time (checked second)
		/// is need and then appends to the file last.
		/// </para>
		/// </remarks>
		virtual protected void AdjustFileBeforeAppend()
		{
			if (m_rollDate) 
			{
				DateTime n = m_dateTime.Now;
				if (n >= m_nextCheck) 
				{
					m_now = n;
					m_nextCheck = NextCheckDate(m_now, m_rollPoint);
	
					RollOverTime(true);
				}
			}
	
			if (m_rollSize) 
			{
				if ((File != null) && ((CountingQuietTextWriter)QuietWriter).Count >= m_maxFileSize) 
				{
					RollOverSize();
				}
			}
		}

		/// <summary>
		/// Creates and opens the file for logging.  If <see cref="StaticLogFileName"/>
		/// is false then the fully qualified name is determined and used.
		/// </summary>
		/// <param name="fileName">the name of the file to open</param>
		/// <param name="append">true to append to existing file</param>
		/// <remarks>
		/// <para>This method will ensure that the directory structure
		/// for the <paramref name="fileName"/> specified exists.</para>
		/// </remarks>
		override protected void OpenFile(string fileName, bool append)
		{
			lock(this)
			{
				fileName = GetNextOutputFileName(fileName);

				// Calculate the current size of the file
				long currentCount = 0;
				if (append) 
				{
					using(SecurityContext.Impersonate(this))
					{
						if (System.IO.File.Exists(fileName))
						{
							currentCount = (new FileInfo(fileName)).Length;
						}
					}
				}
				else
				{
					if (LogLog.IsErrorEnabled)
					{
						// Internal check that the file is not being overwritten
						// If not Appending to an existing file we should have rolled the file out of the
						// way. Therefore we should not be over-writing an existing file.
						// The only exception is if we are not allowed to roll the existing file away.
						if (m_maxSizeRollBackups != 0 && FileExists(fileName))
						{
							LogLog.Error("RollingFileAppender: INTERNAL ERROR. Append is False but OutputFile ["+fileName+"] already exists.");
						}
					}
				}

				if (!m_staticLogFileName) 
				{
					m_scheduledFilename = fileName;
				}

				// Open the file (call the base class to do it)
				base.OpenFile(fileName, append);

				// Set the file size onto the counting writer
				((CountingQuietTextWriter)QuietWriter).Count = currentCount;
			}
		}

		/// <summary>
		/// Get the current output file name
		/// </summary>
		/// <param name="fileName">the base file name</param>
		/// <returns>the output file name</returns>
		/// <remarks>
		/// The output file name is based on the base fileName specified.
		/// If <see cref="StaticLogFileName"/> is set then the output 
		/// file name is the same as the base file passed in. Otherwise
		/// the output file depends on the date pattern, on the count
		/// direction or both.
		/// </remarks>
		protected string GetNextOutputFileName(string fileName)
		{
			if (!m_staticLogFileName) 
			{
				fileName = fileName.Trim();

				if (m_rollDate)
				{
					fileName = fileName + m_now.ToString(m_datePattern, System.Globalization.DateTimeFormatInfo.InvariantInfo);
				}

				if (m_countDirection >= 0) 
				{
					fileName = fileName + '.' + m_curSizeRollBackups;
				}
			}

			return fileName;
		}

		#endregion

		#region Initialize Options

		/// <summary>
		///	Determines curSizeRollBackups (only within the current roll point)
		/// </summary>
		private void DetermineCurSizeRollBackups()
		{
			m_curSizeRollBackups = 0;
	
			string fullPath = null;
			string fileName = null;

			using(SecurityContext.Impersonate(this))
			{
				fullPath = System.IO.Path.GetFullPath(m_baseFileName);
				fileName = System.IO.Path.GetFileName(fullPath);
			}

			ArrayList arrayFiles = GetExistingFiles(fullPath);
			InitializeRollBackups(fileName, arrayFiles);

			LogLog.Debug("RollingFileAppender: curSizeRollBackups starts at ["+m_curSizeRollBackups+"]");
		}

		/// <summary>
		/// Generates a wildcard pattern that can be used to find all files
		/// that are similar to the base file name.
		/// </summary>
		/// <param name="baseFileName"></param>
		/// <returns></returns>
		private static string GetWildcardPatternForFile(string baseFileName)
		{
			return baseFileName + '*';
		}

		/// <summary>
		/// Builds a list of filenames for all files matching the base filename plus a file
		/// pattern.
		/// </summary>
		/// <param name="baseFilePath"></param>
		/// <returns></returns>
		private ArrayList GetExistingFiles(string baseFilePath)
		{
			ArrayList alFiles = new ArrayList();

			string directory = null;

			using(SecurityContext.Impersonate(this))
			{
				string fullPath = Path.GetFullPath(baseFilePath);

				directory = Path.GetDirectoryName(fullPath);
				if (Directory.Exists(directory))
				{
					string baseFileName = Path.GetFileName(fullPath);

					string[] files = Directory.GetFiles(directory, GetWildcardPatternForFile(baseFileName));
	
					if (files != null)
					{
						for (int i = 0; i < files.Length; i++) 
						{
							string curFileName = Path.GetFileName(files[i]);
							if (curFileName.StartsWith(baseFileName))
							{
								alFiles.Add(curFileName);
							}
						}
					}
				}
			}
			LogLog.Debug("RollingFileAppender: Searched for existing files in ["+directory+"]");
			return alFiles;
		}

		/// <summary>
		/// Initiates a roll over if needed for crossing a date boundary since the last run.
		/// </summary>
		private void RollOverIfDateBoundaryCrossing()
		{
			if (m_staticLogFileName && m_rollDate) 
			{
				if (FileExists(m_baseFileName)) 
				{
					DateTime last;
					using(SecurityContext.Impersonate(this))
					{
						last = System.IO.File.GetLastWriteTime(m_baseFileName);
					}
					LogLog.Debug("RollingFileAppender: ["+last.ToString(m_datePattern,System.Globalization.DateTimeFormatInfo.InvariantInfo)+"] vs. ["+m_now.ToString(m_datePattern,System.Globalization.DateTimeFormatInfo.InvariantInfo)+"]");

					if (!(last.ToString(m_datePattern,System.Globalization.DateTimeFormatInfo.InvariantInfo).Equals(m_now.ToString(m_datePattern, System.Globalization.DateTimeFormatInfo.InvariantInfo)))) 
					{
						m_scheduledFilename = m_baseFileName + last.ToString(m_datePattern, System.Globalization.DateTimeFormatInfo.InvariantInfo);
						LogLog.Debug("RollingFileAppender: Initial roll over to ["+m_scheduledFilename+"]");
						RollOverTime(false);
						LogLog.Debug("RollingFileAppender: curSizeRollBackups after rollOver at ["+m_curSizeRollBackups+"]");
					}
				}
			}
		}

		/// <summary>
		/// Initializes based on existing conditions at time of <see cref="ActivateOptions"/>.
		/// </summary>
		/// <remarks>
		/// <para>
		/// Initializes based on existing conditions at time of <see cref="ActivateOptions"/>.
		/// The following is done
		/// <list type="bullet">
		///	<item>determine curSizeRollBackups (only within the current roll point)</item>
		///	<item>initiates a roll over if needed for crossing a date boundary since the last run.</item>
		///	</list>
		///	</para>
		/// </remarks>
		protected void ExistingInit() 
		{
			DetermineCurSizeRollBackups();
			RollOverIfDateBoundaryCrossing();

			// If file exists and we are not appending then roll it out of the way
			if (AppendToFile == false)
			{
				bool fileExists = false;
				string fileName = GetNextOutputFileName(m_baseFileName);

				using(SecurityContext.Impersonate(this))
				{
					fileExists = System.IO.File.Exists(fileName);
				}

				if (fileExists)
				{
					if (m_maxSizeRollBackups == 0)
					{
						LogLog.Debug("RollingFileAppender: Output file ["+fileName+"] already exists. MaxSizeRollBackups is 0; cannot roll. Overwriting existing file.");
					}
					else
					{
						LogLog.Debug("RollingFileAppender: Output file ["+fileName+"] already exists. Not appending to file. Rolling existing file out of the way.");

						RollOverRenameFiles(fileName);
					}
				}
			}
		}

		/// <summary>