Log4net，消除重复的消息

Question

是否有任何选项来设置log4net以消除重复的消息？我有一个循环工作的应用程序......循环中有一个无限循环。如果发生任何错误（例如数据库不可访问），则会在每个循环中一次又一次记录相同的消息。我只需要记录一次该消息。

Answer 1

我已经实现了log4net过滤器，以在指定的时间间隔内消除相同的消息。

类：

public class DuplicityFilter : FilterSkeleton 
{ 
    private String lastMessage = null; 
    private List<Tuple<DateTime, String>> lastMessages = new List<Tuple<DateTime,string>>(); 

    private Int32 _timeWindow = 0; 
    public Int32 timeWindow 
    { 
     get { return _timeWindow; } 
     set { _timeWindow = value; } 
    } 

    public Boolean _lastOnly = false; 
    public Boolean lastOnly 
    { 
     get { return _lastOnly; } 
     set { _lastOnly = value; } 
    } 

    public override FilterDecision Decide(log4net.Core.LoggingEvent loggingEvent) 
    { 
     if (_lastOnly) 
     { 
      if (lastMessage == loggingEvent.RenderedMessage) 
      { 
       return FilterDecision.Deny; 
      } 
      else 
      { 
       lastMessage = loggingEvent.RenderedMessage; 
       return FilterDecision.Accept; 
      } 
     } 
     else 
     { 
      if (_timeWindow <= 0) 
       return FilterDecision.Accept; 

      // Removes old messages 
      lastMessages.RemoveAll(m => m.Item1 < DateTime.Now.AddSeconds(0 - _timeWindow)); 

      if (!lastMessages.Any(m => m.Item2 == loggingEvent.RenderedMessage)) 
      { 
       lastMessages.Add(new Tuple<DateTime, string>(loggingEvent.TimeStamp, loggingEvent.RenderedMessage)); 
       return FilterDecision.Accept; 
      } 
      else 
      { 
       return FilterDecision.Deny; 
      } 
     } 
    } 

和XML定义：

<filter type="your.namespace.here.DuplicityFilter"> 
    <timeWindow value="900" /> <!-- 15min --> 
    <lastOnly value="false" /> 
    </filter>