CsTool.Logger is a compact, fast, basic multi-threaded logger for C# .NET Core and .NET Framework.
It is licenced under Apache License Version 2.0, January 2004 http://www.apache.org/licenses/
CsTool.Logger is a simple adaptation of a very old C/C++ logger I ported to C# then simplified and optimised for good performance and simplicity and inclusion in Customer applications.
It has been performance tested against nlog and serilog for simple logging. It is used in real time and critical applications, avoiding the need for too many external libraries.
You might also find the class based xml configuration file interface nice and simple compared to other solutions.
The project is supported by Visual Studio 2026. It was last tested extensively using Framework 4.8.0 with basic testing under Core 3.1.
If using Visual Studio 2022 the .Net 10 builds don't work. Remove Net10 from the project build target.
Performance testing was conducted against NLog and Serilog but those test projects have been excluded from this release to avoid the need for downloading NuGet packages you won't need as you would be using CsTool.Logger instead of NLog or Serilog.
CsTool.Logger will operate alongside NLog and Serilog but only if full namespaces are used to differentiate between "Logger" classes. CsTool.Logger supports multiple logging streams.
CsTool.Logger.dll Version 2.1.0 (Stable)
Version 2.1.0 now builds for .Net 4.8.0, 4.8.1, .NET 8 and .NET 10.
The only method that might cause issues is the MessageBox method that I have left in for very old app compatibility. I used Copilot modernize to assist make it .NET compatible, it compiles but is not tested. In the future it is not intended for this library to have any direct windows interface dependency.
The latest release is currently only available by downloading the project and compiling it. NuGet packaging is on the list of things to do.
- now testing NeGet.
The toolset DLL is labelled Version 2 as this project is a consolidation/simplification of earlier logging implementations (v1.x) to a form suitable for sharing and caring. This is the author's first sizeable project release to GitHub. The author only codes part time, more so as a hobby than anything else. Use in the work environment is limited, though an earlier synchronous release (v1) of this code has been included in critical real-time applications that have been operating 24x7 quite successfully for many years dating back to .NET 2.0. The asynchronous queueing was not present. An even earlier release would support C, C++ on GCC, windows and embedded systems. As such the underlying framework as simple as it is should be mature. The author uses this logger library in every single project.
V2 is stable and was created and bench marked against both NLog and Serilog as an exercise to determine if it was productive to continue supporting one's own logger library or adopting a 3rd party library. The conclusion was to maintain one's own library (due to simplicity and good performance) but massage it into a form that might be re useable by others. Deep inspection of the source code may identify the odd inconsistency in functional comments, i.e. referencing a feature that does not appear to exist in this release. This is a consequence of migrating legacy code, simplifying and removing code bloat et al to create this simpler implementation.
From a GitHub release perspective, this is my first release so I am not sure what issues might arise from others downloading and using it. Please consider it a Beta Release and conduct some testing of your own. The author has tested this with single and multiple log producers during performance load tests but does not consider this testing definitive. Testing was conducted with .NET Framework 4.8 and Core 3.1 only. The current release has been updated to use the latest .NET runtimes 4.8.1 and 7.0 respectively.
Others are welcome to contribute, though the author requests that changes be kept simple. If you want a complex, feature rich logger, look elsewhere or build over CsTool.LoggerSrc to expand it's capabilities. Both NLog and Serilog appear to be excellent functionally rich loggers.
CsTool.Logger may be included into you Visual Studio project in a number of ways:
- Directly into your C# application directly by including CsTool.LoggerSrc using VS code sharing and instantiating the logger in Program.cs
- By including CsTool.Logger.dll in your .NET Framework or .NET Core project (C#, VB, ASP etc)
CsTool.logger is intended to be simple and very efficient causing minimal disruption to process work flow. Only a basic understanding of C# is needed to use this library as a DLL or inline.
With .NET 10 and Visual Studio 2026, the library is built for both .NET Framework and .NET Core. The same source code is used for both implementations, with some conditional compilation to allow for differences in the underlying framework. The CsTool.LoggerSrc project contains the shared source code. The CsTool.Logger and CsTool.Core.Logger projects are the respective Framework and Core implementations that reference the shared source.
The implementation manages programme folder locations for .NET Framework and will locate a suitable writeable location should the application be called from a read only location.
At this time .NET core code for checking writability of the folder location is not implemented. So ensure the log folder location used is writeable. The best way to achieve this is to start the application with the start up folder being a location other than Program Files. The logger will then create a subfolder called log under the startup location. Multiple instances of an application may be run concurrently provided that either the application start up folder is unique or the Application selects a unique logger folder.
This logger was tested against Serilog and NLog and for the use case I tested, was faster than both when used in Asynchronous mode, primarily due to its simplicity.
For example on 24th May 2020 i7 @4.7GHz 6 core/12 threads the Single producer test application achieved approximately 330000 log events per second (a string + a value).
Unlike NLog and Serilog, CsTool.Logger does not implement complex logging interfaces, rather leaving that to the application. It may however, be extended as needs be. Pre processing log information prior to calling the LogMessage/Write functions is simple but least efficient. Implementing class specific handlers will provide the most efficient solution but a little more effort and will necessitate inclusion of the source into your own logging DLL or application.
The structure is such that it should be possible to expand the logger capability, though I have not tried this. If you have difficulty or suggestions on how the class structure should be revised, please assist.
The solution contains multiple projects as described in each of the solution sections below:
These projects demonstrate/test usage of CsTool.Logger DLL (or CsTool.LoggerSrc shred source) with .NET Framework. The DLL has been used extensively with .NET Framework console and WPF applications and DLLs.
.NET Framework DLL: Include this DLL in your .NET core project. See Tests\Test.Core.Logger1 for usage. Alternatively, for advanced users and for extending logger functionality the shared source may be utilised. See Tests\Test.Core.Logger2 for usage.
.NET Framework Test Application using CsTool.Core.Logger DLL The test code itself is a shared project Test.LoggerSrc
.NET Framework Test Application using CsTool.Core.LoggerSrc directly without needing the DLL The test code itself is a shared project Test.LoggerSrc
These projects demonstrate/test usage of CsTool.Logger DLL (or CsTool.LoggerSrc shred source) with .NET Core. Log file location safety checks are not fully implemented. The code assumes the location is writeable.
.NET Core DLL: Include this DLL in your .NET core project. See Tests\Test.Core.Logger1 for usage. Alternatively, for advanced users and for extending logger functionality the shared source may be utilised. See Tests\Test.Core.Logger2 for usage.
.NET Core Test Application using CsTool.Core.Logger DLL The test code itself is a shared project Test.LoggerSrc
This is the source code for the logger class.
This is the example Test application source code. Shared source is used to ensure that at all times the implementation supports both Core and Framework .NET implementations. The test applications provided use the same test source code but demonstrate different ways of linking or including the logger class.
This is on the TODO list. I am getting ready to update the project for multiple frameworks before creating my first NuGet package. Any assistance would be welcome. At present I have a CsTool.Core.Logger implementation and CsTool.Logger for Framework. That latter has a few simple Windows.Forms add ons for messaging. Simple to #define out or incorporate into a separate package. Other than that it should be fine for Core and Framework, all code existing in a shared source project barring the ShowMessage()...
// Include CsTool.Logger for Framework, or CsTool.Core.Logger for .NET Core
using CsTool.Logger;
namespace MyApplication
{
public class MyClass
{
static int Main(string[] args)
{
try
{
...
Logger.Write("Welcome to my app");
...
Logger.Write(LogEventLevel.Verbose,"Arguments: {0}", string.Join(" ",args));
...
throw new NotImplementedException("Not yet implemented");
}
catch ( Exception exception)
{
// Log the exception
Logger.Write(exception, "Bugger");
}
finally
{
Logger.Write("Bye");
}
}
}
}The Logger supports three conventions for log priority. Maximum options for priority are available when using the native LogPriority levels.
- My Logger historical syntax: LogPriority.{Level}
public enum LogPriority : Int32
{
// Lowest value
Always = 0, // Log requests with this priority will always log
Fatal = 1, // Programme cannot continue
ImportantInfo = 2, // Equivalent to Info except will be logged if LogPriority.ErrorCritical is enabled
ErrorCritical = 3, // Exceptions and bad processing errors likely to require code modification
ErrorProcessing = 4, // Normal processing/data errors
Warning = 5, // Data processing or warnings (high priority debug messages)
Info = 6, // General information
Debug = 7, // More detail on processing activities
Verbose = 8, // Extensive detail on processing where used
Never = 9999 // If requests were to use this level, it would never log
// Highest value
}- Serilog compatible levels. This is a subset of LogPriority.
public enum LogEventLevel : Int32
{
Verbose = LogPriority.Verbose,
Debug = LogPriority.Debug,
Information = LogPriority.Info,
Warning = LogPriority.Warning,
Error = LogPriority.ErrorCritical,
Fatal = LogPriority.Fatal
}- Nlog compatibility is limited but may be easily extended by expanding the Logger class or migrate to CsTool.Logger or Serilog formats.
Logger.Info("For info: {0}...",...);
Logger.Debug("Some details: {0}...",...);
Logger.Fatal(exception,"An exception: {0}",...);
Logger.Log(LogLevel.Info,"For info: {0}...",...);In addition, the level at which logs are written may be set using the Logger.LogThresholdMaxLevel property. This may be set at any time and will affect all log messages written after the change.
public enum DebugThresholdLevel : Int32
{
LogNothing = (-1),
// Lowest enumeration - most important
LogFatal = LogPriority.Fatal,
LogImportantInfo = LogPriority.ImportantInfo,
LogCritical = LogPriority.ErrorCritical,
LogError = LogPriority.ErrorProcessing,
LogWarning = LogPriority.Warning ,
LogInfo = LogPriority.Info,
LogDebug = LogPriority.Debug,
LogVerbose = LogPriority.Verbose,
LogEverything = (LogPriority.Never - 1)
}
// Default log level:
Logger.LogThresholdMaxLevel = DebugThresholdLevel.LogEverything;There are more options available. Some are exposed directly in Logger.*, whilst others are only available via Logger.Instance. Some legacy features have not yet been ported or exposed.
The log file path may be modified at any time, but is best done well before your application start processing. The path and file prepend details may be changed at any time. The log file is closed and reopened when the path is changed.
The File name convention supports: File Prepend text, enable user name, date and time.
// Include CsTool.Logger
using CsTool.Logger;
namespace MyApplication
{
public class MyClass
{
public void DoSomething()
{
// Perform as much tuning right at the start of your programme BEFORE
// logging occurs. If the Logger is used prior to tuning, system defaults
// will be active and the initial log entries will be written to the default location.
// This is OK, just potentially messy for application debugging on start up.
//
// Default file name is {ApplicationName}.log
// Customisable to: {FilePrepend}_{UserName}_{DateTime}.log
//
Logger.Instance.EnableUserNamePrepend = true;
Logger.FilePrepend = "MyLogs";
Logger.FileNameDateFilter = "yyyy-MM-dd";
// Tailor where the log files are stored. The default location is the startup
// folder. Specifically {StartupFolder}\Logs. If the folder is not writeable, the
// log files will be stored in the user's AppData\Local\Temp folder.
// Environment variables are supported.
Logger.Instance.SetLogDirectory("%SPECIALLOGS%");
// Set the logging level. This can be changed at any time
// Default is DebugThresholdLevel.Everything
Logger.LogThresholdMaxLevel = DebugThresholdLevel.LogWarning;
// Optionally you can tune it
Logger.IsLoseMessageOnBufferFull = true; // Default false
Logger.CountLoggedMessagesMaximum = 10000; // Default 100000
Logger.CountOldLogFilesToKeep = 2; // Default 20
// If the logger DLL is compiled with DEBUG defined, you can also manipulate
// Queueing and Async. This is only really useful when including the shared source
// and is not intended for users, only Logger developers.
Logger.Instance.IsSynchronousLogger = false; // Default true
Logger.Instance.IsQueueAsyncEnabled = true; // Default true
Logger.Instance.AddMessageMaxTime = 0; // Debug thingy for testing performance
// Use it
ulong arg1 = 0x1ffff0000;
string arg2 = "Hello World";
bool arg3 = true;
// Use of Write, WriteRaw, LogMessage etc are interchangeable, provided for historical reasons
// Please refer to Logger.cs for all public methods
Logger.Write( LogPriority.Info,
"Information Test Message ULong({0}) String({1}) Bool({2})", arg1, arg2, arg3);
// Serilog log priority and Write method compatibility (basic)
Logger.Write( LogEventLevel.Info,
"Information Test Message ULong({0}) String({1}) Bool({2})", arg1, arg2, arg3);
// NLog compatible
Loger.Info("Pre formatted message string");
try
{
...
}
catch ( Exception exception)
{
// Log the exception: Write, WriteRaw, LogMessage etc are interchangeable
Logger.Write(exception, "Well Bugger Me: {0}", arg1);
}
// Monitor the extent of logging using:
uint iDisplayCurrentFileCount = Logger.CountLoggedMessages;
ulong lDisplayTotalCount = Logger.CountLoggedMessagesTotal;
ulong lLostDueToQueueOverflow = Logger.lCountLostMessagesTotal;
// Not useful as the logger is extremely fast
int iHowManyProcessingInBackground = Logger.LogQueueCount;
// Optionally flush at critical points. Otherwise flushing will occur at 2 second
// intervals as defined in partial class LogBase
Logger.CloseAndFlush();
// If you would like to see the latest log file
Logger.DisplayLogFile();
}
public void DoSomethingElse()
{
// Multiple Logger interfaces
LogBase logger1 = new LogBase("Logger1");
LogBase logger2 = new LogBase("Logger2");
logger1.Write("Hello World");
logger2.Write("Hello World");
}
}
}CsTool.Logger has its own log priorities but also supports Serilog priorities. The log levels should be self explanatory as provided by the code snippets below.
Enumerations are used to set the threshold level. For example:
{
Logger.Write(LogPriority.Warning,"This is a warning");
}will be logged if
{
Logger.LogThresholdMaxLevel >= DebugThresholdLevel.LogInfo;
}// i.e.
if ( LogPriority.Warning < Logger.LogThresholdMaxLevel ) Logger.Write("This is logged");The enumerations are described below as excerpt from LogPriority.cs
// CsTool.Logger standard enumerations
public enum LogPriority : Int32
{
// Lowest value
Always = 0, // Log requests with this priority will always log
Fatal = 1, // Programme cannot continue
ImportantInfo = 2, // Equivalent to Info except will be logged if
// LogPriority.ErrorCritical is enabled
ErrorCritical = 3, // Exceptions and bad processing errors likely to
// require code modification
ErrorProcessing = 4, // Normal processing/data errors
Warning = 5, // Data processing or warnings (high priority debug messages)
Info = 6, // General information
Debug = 7, // More detail on processing activities
Verbose = 8, // Extensive detail on processing where used
Never = 9999 // If requests were to use this level, it would never log
// Highest value
}
// Serilog compatibility:
public enum LogEventLevel : Int32
{
Verbose = LogPriority.Verbose,
Debug = LogPriority.Debug,
Information = LogPriority.Info,
Warning = LogPriority.Warning,
Error = LogPriority.ErrorCritical,
Fatal = LogPriority.Fatal
}
public enum DebugThresholdLevel : Int32
{
LogNothing = (-1),
// Lowest enumeration - most important
LogFatal = LogPriority.Fatal,
LogImportantInfo = LogPriority.ImportantInfo,
LogCritical = LogPriority.ErrorCritical,
LogError = LogPriority.ErrorProcessing,
LogWarning = LogPriority.Warning ,
LogInfo = LogPriority.Info,
LogDebug = LogPriority.Debug,
LogVerbose = LogPriority.Verbose,
LogEverything = (LogPriority.Never - 1)
}The AppDefaults class provides a generic interface that allows for class based settings to be retrieved and saved to the AppDefaults file. Abstraction is achieved using Class custom attributes.
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Settings version="2.0.0" lastsaved="11/04/2025 4:00:39 PM +10:00">
<AppDefaults>
<CsTool.Logger>
<LogBase class="LogBase" version="1.0.0" lastsaved="11/04/2025 4:00:40 PM +10:00">
<CountLoggedMessagesMaximum>100000</CountLoggedMessagesMaximum>
<CountOldLogFilesToKeep>20</CountOldLogFilesToKeep>
<FileNameDateFormat></FileNameDateFormat>
<FilePrepend>%APPNAME%</FilePrepend>
<IsConsoleLoggingEnabled>False</IsConsoleLoggingEnabled>
<IsLoseMessageOnBufferFull>False</IsLoseMessageOnBufferFull>
<IsShowMessagesEnabledByDefault>False</IsShowMessagesEnabledByDefault>
<IsUserNameAppended>True</IsUserNameAppended>
<LogFilePath>%TEMP%\Logs\%APPNAME%</LogFilePath>
<LogThresholdMaxLevel-Help usage="LogFatal LogImportantInfo LogCritical LogError LogWarning LogInfo LogDebug LogVerbose" />
<LogThresholdMaxLevel>LogVerbose</LogThresholdMaxLevel>
</LogBase>
</CsTool.Logger>
<MyApp.MyLibrary.MyModel>
<MyModelSettings class="MyModelSettings" version="1.0.0" lastsaved="11/04/2025 4:35:14 PM +10:00">
<Name>Hello</Name>
<Description>Parameters for tuning this model.</Description>
<ConfigFileName>Info from a spreadsheet.xlsx</ConfigFileName>
<ConfigPath>%STARTUPDIR%\Resources</ConfigPath>
<UserPath>%DROPBOX%\Documents\Stuff</UserPath>
<IsAutoLoad>True</IsAutoLoad>
<IsAutoSave>False</IsAutoSave>
<ItemsT count="5" type="List`1" elementType="System.Int32">
<Items>1</Items>
<Items>2</Items>
<Items>3</Items>
<Items>4</Items>
<Items>5</Items>
</ItemsT>
</MyModelSettings>
</MyApp.MyLibrary.MyModel>
</AppDefaults>
</Settings>To name a few:
- NuGet packaging for simpler support on multiple dotnet frameworks
- It looks like some of the Logger tuning parameters have not been exposed properly so you may not be able to change the log priority. Might be fixed.
- Log counters do not generated GUI events.
- The XML Configuration now allows user DLLs, methods to create their own section in a single application settings file based on class attributes with no custom code. I feel this is significant, but it is still immature as a public release. What is implemented does work. Some further improvement possible to make it as abstract and seamless as possible to the coder. No documentation...
- Logging statistics are still immature compared to my old C implementation. But not as relevant these days.
- I'm still not 100% happy with DotNet and programme shut down. Wouldn't it be nice if you could guarantee the logger was the last module to die and thus have everything else logged.
2004
- C, C++ implementation of Logger. Not thread safe.
2011
- C# implementation but embedded within a common utilities library. Partially thread safe.
2014
- Duplicated sections of code into client applications as common client library.
- Separate personal DLL thread safe, fast.
2023
- First upload to GitHub as a private repository. All previous releases were part of other solutions.
2024
- Restored some old Windows Forms dialogue box support to allow old projects to utilise the latest library. The CsTool.Wpf project is not ready for release as a full Wpf replacement to any forms interfaces.
- Added an exception if a new logger is initialised incorrectly. i.e. Do not do: Logger myLogger2 = new Logger("Logger2"); Instead use LogBase myLogger2 = new LogBase("Logger2");
- Registered on NuGet, looking into packaging, but would like to make this multi framework supportable in the build.
2025
- The XML Configuration file interface is cool, but needs documenting and a little more finess with an example.
- Tweaks to Singleton instance in line with more recent C# practices.
2026
- Updated to support .NET 10 and Visual Studio 2026. The same source code.
- New XML Configuration file now supports save from the user interface. Generating a new configuration settings section using a new class is much simpler.
- Further modifications aimed to ensure all log messages are written before shutdown. Test code exists
- but the root cause is not fully understood. At present only log messages in some destructors are not being logged
- because those destructors are being executed after the log file has been closed and message queue remoed.
- If there are critical messages to be captured they can be captured by the log of last resort anyway. Use SafeWrite().
