mizvekov / libunifex

Unified Executors

Overview

The 'libunifex' project is a prototype implementation of the C++ sender/receiver async programming model that is currently being considered for standardisation.

This project contains implementations of the following:

• Schedulers
• Timers
• Asynchronous I/O (Linux w/ io_uring)
• Algorithms that encapsulate certain concurrency patterns
• Async streams
• Cancellation
• Coroutine integration

Status

This project is still evolving and should be considered experimental in nature. No guarantee is made for API or ABI stability.

Build status

• on Github Actions:

Documentation

• Overview
• Concepts
• API Reference
• Topics
  • Cancellation
  • Debugging
  • Customisation Points

Requirements

A recent compiler that supports C++17 or later. Libunifex is known to work with the following compilers:

• GCC, 9.x and later
• Clang, 9.x and later
• MSVC 2019.6 and later

This library also supports C++20 coroutines. You will need to compile with coroutine support enabled if you want to use the coroutine integrations. This generally means adding -std=c++2a or -fcoroutines-ts on Clang (see "Configuring" below).

Note that MSVC 2019.6 support for C++20 coroutines has known issues and is not currently supported.

Linux

The io_uring support on Linux requires a recent kernel version (5.6 or later).

See http://git.kernel.dk/cgit/linux-block/log/?h=for-5.5/io_uring

The io_uring support depends on liburing: https://github.com/axboe/liburing/

Windows

windows_thread_pool executor requires Windows Vista or later.

Building

This project can be built using CMake.

The examples below assume using the Ninja build system. You can use other build systems supported by CMake.

Configuring

First generate the build files under the ./build subdirectory.

From the libunifex project root:

cmake -G Ninja -H. -Bbuild \
      -DCMAKE_CXX_COMPILER:PATH=/path/to/compiler

By default, this builds libunifex in C++17 without coroutines. If you want to turn on coroutines with clang, add:

      -DCMAKE_CXX_FLAGS:STRING=-fcoroutines-ts

To use libc++ with clang, which has coroutine support, you should also add:

      -DCMAKE_CXX_FLAGS:STRING=-stdlib=libc++ \
      -DCMAKE_EXE_LINKER_FLAGS:STRING="-L/path/to/libc++/lib"

If you want to build libunifex as C++20, add:

      -DCMAKE_CXX_STANDARD:STRING=20

Building Library + Running Tests

To build the library and tests.

From the ./build subdirectory run:

ninja

Once the tests have been built you can run them.

From the ./build subdirectory run:

ninja test

License

This project is made available under the Apache License, version 2.0.

See LICENSE.txt for details.

See also:

• Terms of Use - https://opensource.facebook.com/legal/terms
• Privacy Policy - https://opensource.facebook.com/legal/privacy

References

C++ standardisation papers:

• P0443R13 "A Unified Executors Proposal for C++"
• ...