Log4net LoggerMatchFilter - How to filter only in "match whole word" case?

Question

I'm using the Log4net LoggerMatchFilter to log info only from certain class. The thing is that the loggerToMatch property is using StartsWith(string) to compare and as result I get logs also from classes that their name begin with the name of my desired class. My config contains somthing like that:

<filter type="log4net.Filter.LoggerMatchFilter">
    <acceptOnMatch value="true" />      
    <loggerToMatch value="Class.Name.Space.MyClassName" /> 
    </filter>  
<filter type="log4net.Filter.DenyAllFilter" />

In the log I get also lines from classes like: Class.Name.Space.MyClassName123

Is there a way to filter with "match whole word" condition? (My code is c# .Net 3.5)

Answer 1

You can implement such a Filter by eg. inheriting from LoggerMatchFilter so you can reuse some features, while you override the matching algorithm using a full equality comparison instead; loggingEvent.LoggerName == this.LoggerToMatch.

Borrowing from Log4net's code, this looks like:

namespace PFX.Logging
{
    public class LoggerFullMatchFilter : log4net.Filter.LoggerMatchFilter
    {
        public override FilterDecision Decide(LoggingEvent loggingEvent)
        {
            if (loggingEvent == null)
            {
                throw new ArgumentNullException("loggingEvent");
            }

            if (this.LoggerToMatch != null 
                && this.LoggerToMatch.Length != 0 
                && loggingEvent.LoggerName == this.LoggerToMatch
                )
            {
                if (this.AcceptOnMatch)
                {
                    return FilterDecision.Accept;
                }

                return FilterDecision.Deny;
            }

            return FilterDecision.Neutral;
        }
    }
}

You use this custom filter in your configuration as shown below, specifying its fully qualified assembly name (namespace.class, assembly)

<filter type="PFX.Logging.LoggerFullMatchFilter, Lib">
    <acceptOnMatch value="true" />
    <loggerToMatch value="Class.Name.Space.MyClassName" />
</filter>