Does support log4net, including call stack, in the log message

Question

I want to include a stack of calls (for example, the methods that called me) in the log4net message. Is there a standard way to do this?

(I know this will be slow, but I only need to do this on some errors)

Answer 1

Yes - you can get this stack information using the following templates in the template layout:

%type %file %line %method %location %class 

See this PatternLayout documentation for more information.

Edit in response to the comment below:. I don’t think log4net can be configured to write the whole package.

You can always refuse to write for yourself using something like new StackTrace().ToString() , but I assume that you ask if you want this to be configured in the logging configuration.

I will have a deeper look, but I feel that there is no way to customize this, and you will have to implement your own Layout class.

Edit ++ OK - here is the class of the custom template template, which comes from PatternLayout , but adds% layout to the stack.

This code is a little rough - just an illustrative, not a finished product! (for example, you may not have permission to access the stack you are trying to print)

 public class CustomPatternLayout : PatternLayout { public CustomPatternLayout() { this.AddConverter("stack", typeof(StackTraceConverter)); } } public class StackTraceConverter : PatternLayoutConverter { protected override void Convert(TextWriter writer, LoggingEvent loggingEvent) { var stack = new StackTrace(); var frames = stack.GetFrames(); for (var i = 0; i < frames.Length; i++ ) { var frame = frames[i]; // if the stack frame corresponds to still being inside the log4net assembly, skip it. if (frame.GetMethod().DeclaringType.Assembly != typeof(LogManager).Assembly) { writer.WriteLine("{0}.{1} line {2}", frame.GetMethod().DeclaringType.FullName, frame.GetMethod().Name, frame.GetFileLineNumber()); } } } } 

You can then configure this with the following template configuration (note the% stack at the end of the layout):

  <layout type="ScratchPad.CustomPatternLayout,ScratchPad"> <conversionPattern value="%date %-5level %message%newline %type %file %line %method %location %class %stack" /> </layout> 

Answer 2

If you catch exceptions, just write Exception.ToString () , as this will contain the full stack trace, and will be available as a regular log message.

Answer 3

Robs' answer was the best I found, I decided to expand it a bit to print a full stack trace for exceptions only if that helps someone else.

 public class StackTraceConverter : PatternLayoutConverter { private static readonly Assembly _assembly = typeof (PatternLayoutConverter).Assembly; public StackTraceConverter() { base.IgnoresException = false; } protected override void Convert(TextWriter writer, LoggingEvent loggingEvent) { var ex = loggingEvent.ExceptionObject; if (ex == null) return; writer.WriteLine(ex.ToString()); bool displayFilenames = true; // we'll try, but demand may fail var stack = new StackTrace(displayFilenames); int skip = 0; for (var i = 0; i < stack.FrameCount; i++) { var sf = stack.GetFrame(i); var mb = sf.GetMethod(); if (mb != null) { var t = mb.DeclaringType; if (t.Assembly != _assembly) { //this skips the current method and the method catching the exception if (skip < 2) { skip++; continue; } writer.Write(" at "); // if there is a type (non global method) print it if (t != null) { writer.Write(t.FullName.Replace('+', '.')); writer.Write("."); } writer.Write(mb.Name); // deal with the generic portion of the method if (mb is MethodInfo && mb.IsGenericMethod) { Type[] typars = ((MethodInfo) mb).GetGenericArguments(); writer.Write("["); int k = 0; bool fFirstTyParam = true; while (k < typars.Length) { if (fFirstTyParam == false) writer.Write(","); else fFirstTyParam = false; writer.Write(typars[k].Name); k++; } writer.Write("]"); } // arguments printing writer.Write("("); ParameterInfo[] pi = mb.GetParameters(); bool fFirstParam = true; for (int j = 0; j < pi.Length; j++) { if (fFirstParam == false) writer.Write(", "); else fFirstParam = false; String typeName = "<UnknownType>"; if (pi[j].ParameterType != null) typeName = pi[j].ParameterType.Name; writer.Write(typeName + " " + pi[j].Name); } writer.Write(")"); // source location printing if (displayFilenames && (sf.GetILOffset() != -1)) { // If we don't have a PDB or PDB-reading is disabled for the module, // then the file name will be null. String fileName = null; // Getting the filename from a StackFrame is a privileged operation - we won't want // to disclose full path names to arbitrarily untrusted code. Rather than just omit // this we could probably trim to just the filename so it still mostly usefull. try { fileName = sf.GetFileName(); } catch (SecurityException) { // If the demand for displaying filenames fails, then it won't // succeed later in the loop. Avoid repeated exceptions by not trying again. displayFilenames = false; } if (fileName != null) { // tack on " in c:\tmp\MyFile.cs:line 5" writer.Write(" in {0}:line {1}", fileName, sf.GetFileLineNumber()); } } writer.WriteLine(); } } } } } 

Answer 4

This is not the cleanest approach, but a quick way to achieve this is to create an artificial exception containing the required stack trace:

 public class ArtificialStackTraceException : Exception { public ArtificialStackTraceException( bool shouldIncludeFileInfo = true, string message = "Artificial exception used to generate a stack trace." ) : base(message) { var stackTrace = new System.Diagnostics.StackTrace(shouldIncludeFileInfo); StackTrace = stackTrace.ToString(); } public override string StackTrace { get; } public override string ToString() { return $"{nameof(ArtificialStackTraceException)}:{Environment.NewLine}{StackTrace}"; } } 

( full source )

Then you can use it like this:

 Log.Error("It went kaboom", new ArtificialStackTraceException());