rclcpp_async

A header-only C++20 coroutine library that brings async/await to ROS 2.

Write asynchronous ROS 2 code that reads like sequential code -- no callback nesting, no deadlocks, no std::mutex, no state machines -- all on a single-threaded executor.

Features

• Subscribers -- async streams with co_await stream->next()
• Service client -- co_await ctx.send_request(...) with no shared futures
• Service server -- coroutine handlers that can co_await internally
• Action client -- goal streaming with co_await stream->next() for feedback
• Action server -- coroutine handlers that can co_await internally
• Timers -- periodic async streams
• Concurrency primitives -- when_all, when_any, Event, Mutex, Channel
• Cancellation -- task.cancel() throws CancelledException at co_await points
• Timeout -- ctx.wait_for(awaitable, timeout) returns Result<T>
• Plus
  • TF lookups -- co_await tf.lookup_transform(...) via TfBuffer
  • Single-goal action server -- handles one goal at a time (like ROS 1 SimpleActionServer) with automatic preemption

Quick Start

#include <rclcpp/rclcpp.hpp>
#include "rclcpp_async/rclcpp_async.hpp"

rclcpp_async::Task<void> run(rclcpp_async::CoContext & ctx)
{
  co_await ctx.sleep(std::chrono::seconds(1));
  RCLCPP_INFO(ctx.node().get_logger(), "Hello from coroutine!");
}

int main(int argc, char * argv[])
{
  rclcpp::init(argc, argv);
  auto node = std::make_shared<rclcpp::Node>("hello");
  rclcpp_async::CoContext ctx(*node);

  auto task = ctx.create_task(run(ctx));

  rclcpp::spin(node);
  rclcpp::shutdown();
}

Every coroutine returns Task<T> and is launched with ctx.create_task(...). The standard rclcpp::spin() drives execution -- no special executor needed.

Learn More

• Getting Started -- prerequisites, installation, and a walkthrough of the Quick Start example
• Guide -- topics, services, actions, concurrency primitives, cancellation, and TF lookups
• API Reference -- full list of public types and methods