Stay Safe under Panic: Affine Rust Programming with Multiparty Session Types

TL;DR

This paper introduces affine multiparty session types (AMPST) for Rust, enabling safe, reliable communication among distributed components with automatic cancellation and synchronization, demonstrated through practical protocol implementations.

Contribution

It extends multiparty session types with affine channels and cancellation, providing a new typing discipline and an automated Rust API generator for safe communication protocols.

Findings

MultiCrusty efficiently generates Rust APIs for communication protocols.

AMPST guarantees cancellation termination and prevents deadlocks.

Implemented protocols include OAuth, SMTP, and exception handling patterns.

Abstract

Communicating systems comprise diverse software components across networks. To ensure their robustness, modern programming languages such as Rust provide both strongly typed channels, whose usage is guaranteed to be affine (at most once), and cancellation operations over binary channels. For coordinating components to correctly communicate and synchronise with each other, we use the structuring mechanism from multiparty session types, extending it with affine communication channels and implicit/explicit cancellation mechanisms. This new typing discipline, affine multiparty session types (AMPST), ensures cancellation termination of multiple, independently running components and guarantees that communication will not get stuck due to error or abrupt termination. Guided by AMPST, we implemented an automated generation tool (MultiCrusty) of Rust APIs associated with cancellation termination algorithms, by which the Rust compiler auto-detects unsafe programs. Our evaluation shows that MultiCrusty provides an efficient mechanism for communication, synchronisation and propagation of the notifications of cancellation for arbitrary processes. We have implemented several usecases, including popular application protocols (OAuth, SMTP), and protocols with exception handling patterns (circuit breaker, distributed logging).