CppCon 2019

Async in C++ is in a sad state. The standard tools -- promises, futures, threads, locks, and std::async -- are either inefficient, broken, or both. Even worse, there is no standard way to say _where_ work should happen. Parallel algorithms, heterogeneous computing, networking & IO, reactive streams, and more: all critically important foundational technologies that await a standard abstraction for asynchronous computation.

In this talk, Eric Niebler and David Hollman dig into the Standard Committee's search for the basis operations that underpin all asynchronous computation: the long-sought Executor concept. The latest iteration of Executors is based on the Sender/Receiver programming model, which provides a generalization of many existing paradigms in asynchronous programming, including future/promise, message passing, continuation passing, channels, and the observer pattern from reactive programming. It also has surprising and deep connections to coroutines, which further demonstrates the model’s potential to be a truly unifying abstraction for asynchronous programming in C++20 and beyond.

Eric and David will present the short-term and long-term directions for Executors in ISO Standard C++, illustrating the design by walking through several implementation examples. They will talk about the direct connection between coroutines and the Sender/Receiver model and discuss what it means for the future of asynchronous APIs in C++. Finally, they will cover how the restrictions imposed by the Executors model should affect the way you write code today so your code is ready for the next big revolution in parallel and concurrent C++ programming.