SPLog

SPLog is a lightweight logging DLL focused on performance, simplicity, and practical file logging for .NET applications.

GitHub repository: https://github.com/cku3987/SPLog

Targets:

• net8.0
• netstandard2.0
  Usable from .NET Framework 4.7.2 projects and newer compatible runtimes.

Why SPLog

• Simple API
• Fast enough for high-volume application logging
• File logging and console logging out of the box
• External JSON configuration support
• Exception logging support
• Shared error file support
• Daily and hourly rolling
• Append and CreateNew file conflict handling

Quick Start

using SPLog;

using var logger = SPLogFactory.Create(options =>
{
    options.Name = "Core";
    options.EnableConsole = true;
    options.EnableFile = true;
    options.FilePath = "logs";
    options.TimestampFormat = "yyyy-MM-dd HH:mm:ss.fff";
});

logger.Information("application started");
logger.Warning("response delay detected");

try
{
    RunProcess();
}
catch (Exception ex)
{
    logger.Error(ex, "process failed");
}

Shared Error File

Each logger can keep its own main file while Error and Critical messages are also written to one shared error file:

var sharedErrorFile = new SPLogErrorFileOptions
{
    FilePath = "logs/error.log",
    MinimumLevel = LogLevel.Error,
    FileRollingMode = FileRollingMode.Daily
};

using var moduleALog = SPLogFactory.Create(options =>
{
    options.Name = "ModuleA";
    options.EnableFile = true;
    options.FilePath = "logs/module-a";
    options.ErrorFile = sharedErrorFile;
});

using var moduleBLog = SPLogFactory.Create(options =>
{
    options.Name = "ModuleB";
    options.EnableFile = true;
    options.FilePath = "logs/module-b";
    options.ErrorFile = sharedErrorFile;
});

moduleALog.Information("module A started");
moduleALog.Error("module A failed");
moduleBLog.Error("module B failed");

Result:

• module-a/ModuleA_yyyyMMdd.log contains ModuleA normal logs and errors
• module-b/ModuleB_yyyyMMdd.log contains ModuleB normal logs and errors
• logs/error_yyyyMMdd.log contains the ModuleA and ModuleB error lines together

Global Logger With Categories

If you want one global logger but still want subsystem names inside the log, create categories from the root logger:

using var appLog = SPLogFactory.Create(options =>
{
    options.Name = "App";
    options.EnableFile = true;
    options.FilePath = "logs";
});

var coreLog = appLog.CreateCategory("Core");
var networkLog = appLog.CreateCategory("Network");
var socketLog = networkLog.CreateCategory("Socket");

coreLog.Information("core started");
networkLog.Warning("network delay detected");
socketLog.Error("socket closed");

This keeps one shared queue and one shared writer, while log lines are identified as App.Core, App.Network, and App.Network.Socket.

External Configuration

using var logger = SPLogFactory.CreateFromJsonFile("config/splog.core.json");

Example JSON:

{
  "Name": "Core",
  "MinimumLevel": "Information",
  "TimestampFormat": "yyyy-MM-dd HH:mm:ss.fff",
  "EnableConsole": false,
  "EnableFile": true,
  "FilePath": "logs",
  "ErrorFile": {
    "FilePath": "logs/error.log",
    "MinimumLevel": "Error",
    "UseUtcTimestamp": false,
    "FileConflictMode": "Append",
    "FileRollingMode": "Daily",
    "MaxFileSizeBytes": 10485760,
    "MaxRollingFiles": 14,
    "FileBufferSize": 65536
  },
  "FileConflictMode": "Append",
  "FileRollingMode": "Hourly",
  "MaxFileSizeBytes": 10485760,
  "MaxRollingFiles": 100,
  "QueueCapacity": 8192,
  "BatchSize": 10,
  "FlushIntervalMs": 100,
  "FileBufferSize": 65536
}

File Naming Behavior

• FilePath = "logs" creates <Name>.log automatically when the first log entry is written
• Relative paths are resolved from AppContext.BaseDirectory
• Absolute paths are used as-is

Examples:

• Daily + Append -> Core_20260331.log
• Daily + CreateNew -> Core_20260331.log, then Core_20260331_001.log
• Hourly + CreateNew -> Core_20260331_13.log, then Core_20260331_13_001.log

Validation Projects

This repository also includes validation helpers:

• SPLog.Tests Deterministic correctness checks
• SPLog.StressRunner Stress, smoke, and long-run validation for one or many loggers at the same time
• SPLog.Net472.Verify Real .NET Framework 4.7.2 reference/build/run verification

Recommended commands:

dotnet build SPLog.sln -c Release -m:1
dotnet run --project SPLog.Tests\SPLog.Tests.csproj -c Release --no-build
dotnet run --project SPLog.StressRunner\SPLog.StressRunner.csproj -c Release -- --config codex\SPLog-StressRunner.sample.json
dotnet run --project SPLog.Net472.Verify\SPLog.Net472.Verify.csproj -c Release

The default stress sample includes:

• multiple logger scenarios running at the same time
• one root logger used directly and shared by multiple category scenarios
• additional independent loggers using separate file paths
• a 5-digit stress-run timestamp format for easier timing inspection
• a configuration that is safe to auto-load when launching from Visual Studio

Documentation

• English guide: docs/SPLog-Guide-EN.html
• Korean guide: docs/SPLog-Guide-KO.html
• Validation guide: codex/SPLog-Validation-Guide-EN.md

Project Link

• GitHub: https://github.com/cku3987/SPLog