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arrp: Auto Returning Resource Pool for Modern C++

Objective

Design a resource pool with ease of use and safety guarantees using RAII principles to ensure:

• Stored object lifetime management
• Stored object restored to the pool
• Strict scoped checkout and checkin semantics

Quick Start

#include "siddiqsoft/resource_pool.hpp"
#include <memory>

class DatabaseConnection {
public:
    void execute(const std::string& query) { /* ... */ }
};

int main() {
    // Create a resource pool
    siddiqsoft::arrp::resource_pool<std::shared_ptr<DatabaseConnection>> pool;

    // Populate the pool
    for (int i = 0; i < 5; ++i) {
        pool.return_to_pool(std::make_shared<DatabaseConnection>());
    }

    // Borrow and use a resource
    {
        auto conn = pool.borrow_from_pool();
        conn->execute("SELECT * FROM users");
        // Automatically returned to pool when going out of scope
    }

    return 0;
}

Features

• Thread-Safe: All operations are protected by mutexes for concurrent access
• RAII Pattern: Automatic resource return via scoped_resource wrapper
• Capacity Management: Enforces maximum capacity limits to prevent unbounded growth
• FIFO Ordering: Resources retrieved from front, added to back
• Customizable Factory: Support for custom resource creation callbacks
• Diagnostic Counters: Track borrow, return, and auto-add operations
• Modern C++20: Uses only standard library features (no external dependencies)
• Type-Safe: Leverages C++20 concepts for compile-time type checking
• Move Semantics: Efficient resource transfer with perfect forwarding

Requirements

• Language: C++20 minimum required for std::jthread, std::mutex, std::recursive_mutex, std::scoped_lock, std::unique_lock
• Optional: nlohmann::json for JSON serialization support
• No External Dependencies: Only uses standard library features
• Platform Support: MacOS, Linux, Windows
  • MacOS: Development platform
  • Linux (RedHat): CI pipeline tested
  • Windows: CI pipeline tested

Compiler Support

• GCC: 10+ (Linux)
• Clang:
  • AppleClang v21+
  • LLVM v20+
• MSVC:
  • Visual Studio 2019
  • Visual Studio 2022
  • Visual Studio 2026

Installation

Using CMake (Recommended)

include(FetchContent)
FetchContent_Declare(arrp
    GIT_REPOSITORY https://github.com/SiddiqSoft/arrp.git
    GIT_TAG main
)
FetchContent_MakeAvailable(arrp)

target_link_libraries(your_target PRIVATE arrp::arrp)

Using NuGet (Windows)

nuget install SiddiqSoft.aarp

Manual Integration

Simply include the header files from include/siddiqsoft/ in your project.

Documentation

For detailed documentation, see:

• Getting Started - Installation and setup guide
• Usage Guide - Detailed usage examples and best practices
• API Reference - Complete API documentation
• Examples - Real-world code examples
• Quick Reference - Quick lookup guide
• Security - Security considerations

Key Components

Component	Description	Use Case
resource_pool<T>	Thread-safe resource pool manager	Connection/resource management
scoped_resource<T>	RAII resource wrapper	Automatic resource return

Design Principles

• Move Semantics: All components use move semantics for efficient resource transfer
• RAII: Proper resource management through constructors and destructors
• Thread Safety: Internal synchronization using mutexes and scoped locks
• Zero-Copy: Minimal data copying through perfect forwarding
• Type Safety: C++20 concepts ensure compile-time type checking
• Simplicity: Clean API that hides complexity of resource management

License

BSD 3-Clause License - See LICENSE file for details

Copyright

Copyright (c) 2026, Abdulkareem Siddiq. All rights reserved.

Links

• GitHub: https://github.com/SiddiqSoft/arrp
• NuGet: https://www.nuget.org/packages/SiddiqSoft.aarp/
• Documentation: https://siddiqsoft.github.io/arrp/