📘 Logger C++ Library

A lightweight, high-performance, thread-friendly logging library for C++ featuring stream-style macros, automatic log rotation, configurable log levels, file logging, console logging, and internal cache support.

📦 Dependency

This project uses my reusable utility library cpp-utils for common internal components such as thread-safe queueing and shared utilities.

🔗 https://github.com/jayasankar-jp/cpp-utils

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🔗 Repository

git clone git@github.com:jayasankar-jp/logger-cpp.git
cd logger-cpp

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⚙️ Installation

📦 Install Dependency: cpp-utils

This project requires cpp-utils.

git clone https://github.com/jayasankar-jp/cpp-utils.git
cd cpp-utils
mkdir build
cd build
cmake ..
make
sudo make install

✅ Build logger-cpp

Navigate to your project directory.

git clone git@github.com:jayasankar-jp/logger-cpp.git
cd logger-cpp
mkdir build
cd build
cmake ..
make

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✅ Install

sudo make install

📦 Installed Files

Type	Path
Library	/usr/local/lib/libLogger.a
Headers	/usr/local/include/
CMake Config	/usr/local/lib/cmake/Logger/

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🚀 Quick Start

✅ Basic Example

#include <Logger.h>

int main()
{
    Logger::getInstance();

    Logger::setAppName("MQTT_APP");
    Logger::setLogPath("./LOGS");
    Logger::setLogLevel(127);

    log_info     << "Application Started";
    log_error    << "Connection Failed";
    log_warn     << "Retrying";
    log_debug    << "Debug Data = " << 10;
    log_critical << "Critical Error";

    return 0;
}

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⚡ Multithreaded Example

#include <Logger.h>
#include <thread>
#include <chrono>

int main()
{
    Logger::getInstance();

    Logger::setAppName("MY_TEST_APP");
    Logger::setLogLevel(127);
    Logger::setMaxFileSizeMB(50);
    Logger::setMaxFileGenPeriodMin(1);

    std::thread([]{
        while(true)
        {
            log_info  << "Thread 1 Running";
            log_debug << "Thread 1 Debug";
        }
    }).detach();

    std::thread([]{
        while(true)
        {
            log_warn     << "Thread 2 Warning";
            log_critical << "Thread 2 Critical";
        }
    }).detach();

    while(true)
        std::this_thread::sleep_for(std::chrono::seconds(10));
}

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🧩 Logging Macros

#define log_error     LogStream(__FILE__, __LINE__, LogLevel::Error)
#define log_info      LogStream(__FILE__, __LINE__, LogLevel::Info)
#define log_critical  LogStream(__FILE__, __LINE__, LogLevel::Critical)
#define log_verbose   LogStream(__FILE__, __LINE__, LogLevel::Verbose)
#define log_warn      LogStream(__FILE__, __LINE__, LogLevel::Warn)
#define log_debug     LogStream(__FILE__, __LINE__, LogLevel::Debug)

Each log automatically includes:

• Timestamp
• File Name
• Line Number
• Log Level
• Message

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📊 Log Levels

Enum Definition

enum class LogLevel
{
    Error    = 1 << 0,
    Info     = 1 << 1,
    Critical = 1 << 2,
    Verbose  = 1 << 3,
    Warn     = 1 << 4,
    Debug    = 1 << 5,
    Console  = 1 << 6
};

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Bitmask Values

Level	Value
Error	1
Info	2
Critical	4
Verbose	8
Warn	16
Debug	32
Console	64

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Examples

Value	Enabled Logs
1	Error
3	Error + Info
31	Error + Info + Critical + Verbose + Warn
63	All File Logs
127	All Logs + Console Output

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Recommended

Logger::setLogLevel(127);

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📁 Log File Output

<LOG_PATH>/<APP_NAME>_<DATE>_<TIME>.log

Example

./LOGS/MY_TEST_APP_27-04-2026_13:40:12.log

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🔁 Log Rotation

A new log file is created automatically when:

• 📦 File size exceeds limit
• ⏱️ Rotation time reached

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⚙️ Configuration

🔹 Set App Name

Logger::setAppName("MY_APP");

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🔹 Set Log Path

Logger::setLogPath("./LOGS");

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🔹 Set Log Level

Logger::setLogLevel(127);

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🔹 Max File Size

Logger::setMaxFileSizeMB(50);

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🔹 Rotation Time (Minutes)

Logger::setMaxFileGenPeriodMin(10);

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🔹 Disable Internal Cache

Logger::desableCash();

Description:

• Disables internal cache/buffer
• Writes logs more directly to file
• Useful for debugging
• May reduce performance under high logging load

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🧠 Features

• ⚡ High-speed logging
• 🧵 Thread-friendly
• 📁 File logging
• 🖥️ Console logging
• 🔁 File rotation
• 📍 File & line info
• 🔧 Bitmask level control
• 🧱 Stream-style syntax (<<)
• 🔌 Easy CMake integration
• 🧍 Singleton architecture
• 💾 Internal cache support

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🛠 Internal Design

Logger is built using reusable modules from cpp-utils, helping reduce duplicated code and improve maintainability.

Used components may include:

• Thread-safe Queue
• Common utility helpers
• Shared infrastructure modules

🔗 https://github.com/jayasankar-jp/cpp-utils

🧩 CMake Usage

Installed Library

find_package(Logger REQUIRED)

add_executable(app main.cpp)
target_link_libraries(app Logger::Logger)

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Custom Path

list(APPEND CMAKE_PREFIX_PATH "/your/install/path")
find_package(Logger REQUIRED)

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Add Subdirectory

add_subdirectory(logger-cpp)

add_executable(app main.cpp)
target_link_libraries(app Logger)

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⚠️ Notes

• Include:

#include <Logger.h>

• Ensure log directory exists
• Static library build by default
• Use 127 for all logging

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🔮 Future Improvements

• Async lock-free queue
• Shared library (.so)
• JSON structured logs
• Per-module filtering
• Colored console logs
• Cache tuning APIs

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👨‍💻 Author

Jayasankar JP

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⭐ Contributing

Pull requests are welcome.

If you find bugs or want new features, open an issue in the repository.

Note for Contributors

Some internal modules come from cpp-utils.

If making core utility changes, please also review:

🔗 https://github.com/jayasankar-jp/cpp-utils

If you find bugs or want new features, open an issue on GitHub.