bnio

bnio is a C++20 async I/O library. Every operation is a lazy sender that composes with the standard receiver pattern — TCP, TLS (OpenSSL), UDP, DNS resolution, timers, and composed writes are all built in.

Status: Linux runs on io_uring, macOS and BSD on kqueue. Both backends share the same io_context, TCP, UDP, DNS, timer, and TLS APIs. TLS needs OpenSSL ≥ 1.1.

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Quick start

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build
ctest --test-dir build --output-on-failure

A minimal example — a one-shot timer, the same on either backend:

#include <bnio/bnio.h>
#include <bexec/bexec.hpp>
#include <chrono>
#include <iostream>
#include <ostream>

struct timer_receiver {
  void set_value() noexcept {
    std::cout << "Timer expired successfully." << std::endl;
    ioc.stop();
  }
  void set_error(std::error_code) noexcept {
    std::cout << "An error occured." << std::endl;
    ioc.stop();
  }
  void set_stopped() noexcept {
    std::cout << "Timer was stopped." << std::endl;
    ioc.stop();
  }

  bnio::io_context &ioc;
};

int main() {
  bnio::io_context ctx;
  bnio::steady_timer timer(ctx, std::chrono::milliseconds(100));

  auto sender = timer.async_wait();
  auto op = bexec::connect(std::move(sender), timer_receiver{ctx});
  bexec::start(op);

  ctx.run();  // returns once the timer completes
}

The public API is exposed solely through <bnio/bnio.h>; all other headers are implementation details.

Each async factory returns a lazy sender; bexec::connect binds it to a receiver, bexec::start submits it, and ctx.run() pumps the loop until it finishes. The usage guide covers the sender/receiver model in depth, and examples has TCP, TLS, DNS, and HTTP samples (including a small mini_curl).

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Using bnio

The simplest option is to add bnio straight to your CMake tree:

add_subdirectory(bnio)
target_link_libraries(your_app PRIVATE bnio::bnio)

To install as a system-wide package instead, bnio ships a standard CMake package and a pkg-config file:

cmake --install build --prefix /usr/local

find_package(bnio CONFIG REQUIRED)
target_link_libraries(your_app PRIVATE bnio::bnio)

c++ app.cpp $(pkg-config --cflags --libs bnio)

bnio also builds DEB and RPM packages through CPack. Enable it with BNIO_PACKAGE=ON and run cpack:

cmake -S . -B build-pkg -DCMAKE_BUILD_TYPE=Release -DBNIO_INSTALL=ON -DBNIO_PACKAGE=ON
cmake --build build-pkg
(cd build-pkg && cpack -G DEB && cpack -G RPM)

That gives you a runtime and a development package for each format — libbnio0 / libbnio-dev on Debian-style systems, bnio / bnio-devel on RPM-based ones.

Pre-built DEB and RPM packages are available on the GitHub Releases page — download the latest *.deb or *.rpm and install with your system package manager:

# Debian / Ubuntu
sudo dpkg -i bnio-*-Linux-runtime.deb bnio-*-Linux-development.deb

# Fedora / RHEL / openSUSE
sudo rpm -i bnio-*-Linux-runtime.rpm bnio-*-Linux-development.rpm

Build options, dependency providers, coverage, and packaging details are in docs/build.md.

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License

MIT — see LICENSE.