Logging from .NET framework internals (Logging.On)

Question

I’m debugging some unexpected behavior and while tracing in to the .NET framework I see a bunch of stuff like this:

        if (Logging.On) { 
            Logging.PrintInfo(Logging.Web, this, SR.GetString(SR.net_log_n_certs_after_filtering, filteredCerts.Count));
             …
        }

But (as expected by default) the execution steps right over these. Is there some way to turn on the logging? Or is that just something that the framework developers can do while making special builds of the framework?

Answer 1

Reflectoring around shows that Logging.On is enabled by 'flag' in

s_WebTraceSource = new NclTraceSource("System.Net");
s_HttpListenerTraceSource = new NclTraceSource("System.Net.HttpListener");
s_SocketsTraceSource = new NclTraceSource("System.Net.Sockets");
s_CacheTraceSource = new NclTraceSource("System.Net.Cache");
try
{
   flag = ((s_WebTraceSource.Switch.ShouldTrace(TraceEventType.Critical) || s_HttpListenerTraceSource.Switch.ShouldTrace(TraceEventType.Critical)) || s_SocketsTraceSource.Switch.ShouldTrace(TraceEventType.Critical)) || s_CacheTraceSource.Switch.ShouldTrace(TraceEventType.Critical);
}

This implies it's using standard tracing and just checking to see if at least the "Critical" level is being watched. A sample of how to use this can be found in the "Debugging a Sockets Application" section of this MSDN article as in:

<configuration>
  <system.diagnostics>
    <sources>
      <source name="System.Net.Sockets">
        <listeners>
          <add name="Sockets"/>
        </listeners>
      </source>
    </sources>
    <switches>
      <add name="System.Net.Sockets" value="31" />
    </switches>
    <sharedListeners>
    <add name="Sockets" type="System.Diagnostics.TextWriterTraceListener" 
      initializeData="Sockets.log"/>
    </sharedListeners>
    <trace autoflush="true" />
  </system.diagnostics>
</configuration>

As the article explains, the switch values are bitwise OR's of these five values:

• Network traffic (0x10)
• Method entry and exit (0x8)
• Warnings (0x4)
• Errors (0x2)
• Critical events (0x1).

If you OR all of these (0x10 | 0x8 | 0x4 | 0x2 | 0x1) you get 0x1F which is "31" in decimal as seen above.

Details on setting using an application configuration file can be found here. It should just be a matter of creating an app.config or web.config file similiar to the one above for the source(s) that you'll use.