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Asynchronous Programming with Futures

1 post · Jun 2015

What this trail covers

Meta's asynchronous programming capabilities have evolved with the introduction and widespread adoption of Futures, a pattern for expressing asynchronous computations in a natural and composable way. This includes the development of Folly Futures for C++11, which provides a robust implementation of futures that allows for chaining callbacks, sequential and parallel composition, and explicit control over execution contexts via Executors. The framework addresses the complexities of traditional callback-based asynchronous programming, such as 'callback hell' and 'callback pyramids', by offering cleaner error handling and improved code readability. Case studies from Facebook and Instagram demonstrate significant improvements in latency, robustness, and code maintainability through the adoption of futures.

All Meta trails
  1. Futures for C++11 at FacebookThis post introduces Folly Futures, a C++11 implementation of the futures pattern for asynchronous programming. It details the motivation for asynchrony by contrasting synchronous and asynchronous code, highlighting the inefficiencies of blocking threads. The post explains the core concepts of futures, including their ability to represent pending results and chain operations using `then()` and `onError()`. It demonstrates sequential composition with `then()` and parallel composition using `collect()`. The article also covers execution contexts via the `Executor` interface and the use of `Promise` for creating futures. Case studies from Instagram's recommendation service and other internal applications are presented as evidence of improved latency, robustness, and code readability.