LogMagic

Why LogMagic

Like many other libraries for .NET, LogMagic provides diagnostic logging into files, the console, and elsewhere. It's probably the easiest framework to setup, has a clean API, extremely extensible.

LogMagic also supports a relatively new paradigm of structured logging.

Installation

Installing from NuGet

The core logging package is LogMagic. Supported frameworks are:

• .NET 4.5
• PCL (Portable Library)
• .NET Core support is coming soon

PM> Install-Package LogMagic

Setup

Types are in LogMagic namespace

using LogMagic;

An ILog instance is the one used to log events and can be created in one of three ways by calling to global static L class.

Create using current class type name

ILog _log = L.G();

Or by specifying type explicitly

ILog _log = L.G<T>;			//using generics
ILog _log = L.G(typeof(T));	//passing type

Or by specifying name explicitly

ILog _log = L.G("instance name");

By default LogMagic doesn't write events anywhere and you need to configure it:

L.Config.WriteTo.Console();

This is typically done once at application startup.

Example application

The complete example below shows logging in a simple console application, with events sent to the console as well as to file on disk.

1. Create a new Console Application project
2. Install the core LogMagic package

In Visual Studio, open Package Manager Console and type:

Install-Package LogMagic

3. Add the following code to Program.cs

using System;
using LogMagic;

namespace LogMagicExample
{
   public class Program
   {
      private readonly ILog _log = L.G();

      public static void Main(string[] args)
      {
         L.Config
            .WriteTo.Console()
            .EnrichWith.ThreadId();

         new Program().Run();

         Console.ReadLine();

         L.Shutdown();
      }

      private void Run()
      {
         _log.I("hello, LogMagic!");

         int a = 10, b = 0;

         try
         {
            _log.D("dividing {a} by {b}", a, b);
            Console.WriteLine(a / b);
         }
         catch(Exception ex)
         {
            _log.E("unexpected error", ex);
         }

         _log.D("attempting to divide by zero");
      }

   }
}

4 Run the program

Logging exceptions

LogMagic always check last parameter of log arguments whether it's an exception class and eliminates from the argument list.

Visual Studio Snippets

Visual Studio snippets are installed along with the NuGet package so you can use them straight away with any project:

ldef defines a logging variable inside the class:

private static readonly LogMagic.ILog log = LogMagic.L.G(typeof(container_class));

ld writes a logging statement:

log.D("...");

there are identical shortcuts for other logging levels le, li, lw.

Configuration basics

LogMagic uses C# API to configure logging.

Log writers

Log event writers generally record log events to some external representation, typically console, file, or external data store. LogMagic has a few built-in writers to get you started. More writers are redistributed via NuGet.

A curated list of available packages are listed below on this page.

Writers are configure using WriteTo congiguration object.

L.Config.WriteTo.PoshConsole();

Multiple writers can be active at the same time.

L.Config
	.WriteTo.PoshConsole()
    .WriteTo.Trace();

Formatting

Text-based writers support message formatting. Whenever a format parameter appears in writer configuration you can specify your own one:

L.Config
	.EnrichWith.ThreadId()
	.WriteTo.Console("{time:H:mm:ss,fff}|{threadId}{level,-7}|{source}|{message}{error}");

Enriched properties can also appear in the output. In the example above a threadId comes from thread ID ennricher.

Formatting syntax

Built-in property names:

• {time} - used to reference event time
• {level} - prints message severity
• {source} - logging source name
• {message} - log message
• {error} - error

All of the properties support standard .NET formatting used in string.Format().

Enrichers

Enrickers are simple components that add properties to a log event. This can be used for the purpose of attaching a thread id, machine IP address etc. for example.

L.Config.EnrichWith.ThreadId();

Writing log events

Log events are written to writers using the ILog interface. Typically you will instantiate it on top of your class definition you want to log from.

private readonly ILog _log = L.G<Class>();

// ...

_log.I("application v{version} started on {date}", "1.0", DateTime.UtcNow);

Message template syntax

the string above "application v{version} started on {date}" is a message template. Message templates are superset of standard .NET format string, so any format string acceptable to string.Format() will also be correctly processed by LogMagic.

• Property names are written between { and } brackets
• Formats that use numeric property names, like {0} and {1} exclusively, will be matched with the log method's parameters by treating the property names as indexes; this is identical to string.Format()'s behavior
• If any of the property names are non-numeric, then all property names will be matched from left-to-right with the log method's parameters
• Property names, both numeric and named, may be suffixed with an optional format, e.g. :000 to control how the property is rendered; these format strings behave exactly as their counterparts within the string.Format() syntax

Log event levels

LogMagic uses levels as the primary means for assigning importance to log events. The levels in increasing order of importance are:

1. Debug - internal control flow and diagnostic state dumps to facilitate pinpointing of recognised problems
2. Information - events of interest or that have relevance to outside observers
3. Warning - indicators of possible issues or service degradation
4. Error - fa failure within application or connected system, critical errors causing complete failure

Provided Writers and Enrichers

Writers

Enrichers