PatternFileAppender.cs :  » Logging-Tools » log4net » SampleAppendersApp » Appender » C# / CSharp Open Source

#region Copyright & License
//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
using System.IO;
using System.Text;
using log4net.Appender;
using log4net.Util;
using log4net.Layout;
using log4net.Core;

namespace SampleAppendersApp.Appender{
  /// <summary>
  /// Appender that writes to a file named using a pattern
  /// </summary>
  /// <remarks>
  /// The file to write to is selected for each event using a
  /// PatternLayout specified in the File property. This allows
  /// each LoggingEvent to be written to a file based on properties
  /// of the event.
  /// The output file is opened to write each LoggingEvent as it arrives
  /// and closed afterwards.
  /// </remarks>
  public class PatternFileAppender : AppenderSkeleton
  {
    public PatternFileAppender()
    {
    }

    public PatternLayout File
    {
      get { return m_filePattern; }
      set { m_filePattern = value; }
    }

    public Encoding Encoding
    {
      get { return m_encoding; }
      set { m_encoding = value; }
    }

    public SecurityContext SecurityContext 
    {
      get { return m_securityContext; }
      set { m_securityContext = value; }
    }

    override public void ActivateOptions() 
    {  
      base.ActivateOptions();

      if (m_securityContext == null)
      {
        m_securityContext = SecurityContextProvider.DefaultProvider.CreateSecurityContext(this);
      }
    }

    override protected void Append(LoggingEvent loggingEvent) 
    {
      try
      {
        // Render the file name
        StringWriter stringWriter = new StringWriter();
        m_filePattern.Format(stringWriter, loggingEvent);
        string fileName = stringWriter.ToString();

        fileName = SystemInfo.ConvertToFullPath(fileName);

        FileStream fileStream = null;

        using(m_securityContext.Impersonate(this))
        {
          // Ensure that the directory structure exists
          string directoryFullName = Path.GetDirectoryName(fileName);

          // Only create the directory if it does not exist
          // doing this check here resolves some permissions failures
          if (!Directory.Exists(directoryFullName))
          {
            Directory.CreateDirectory(directoryFullName);
          }

          // Open file stream while impersonating
          fileStream = new FileStream(fileName, FileMode.Append, FileAccess.Write, FileShare.Read);
        }

        if (fileStream != null)
        {
          using(StreamWriter streamWriter = new StreamWriter(fileStream, m_encoding))
          {
            RenderLoggingEvent(streamWriter, loggingEvent);
          }

          fileStream.Close();
        }
      }
      catch(Exception ex)
      {
        ErrorHandler.Error("Failed to append to file", ex);
      }
    }

    private PatternLayout m_filePattern = null;
    private Encoding m_encoding = Encoding.Default;
    private SecurityContext m_securityContext;
  }
}