The Swift concurrency model intends to provide a safe programming model that statically detects data races and other common concurrency bugs. The Structured Concurrency proposal introduces a way to define concurrent tasks and provides data-race safety for functions and closures. This model is suitable for a number of common design patterns, including things like parallel maps and concurrent callback patterns, but is limited to working with state that is captured by closures.

Swift includes classes, which provide a mechanism for declaring mutable state that is shared across the program. Classes, however, are notoriously difficult to correctly use within concurrent programs, requiring error-prone manual synchronization to avoid data races. We want to provide the ability to use shared mutable state while still providing static detection of data races and other common concurrency bugs.

The actor model defines entities called actors that are perfect for this task. Actors allow you as a programmer to declare that a bag of state is held within a concurrency domain and then define multiple operations that act upon it. Each actor protects its own data through data isolation, ensuring that only a single thread will access that data at a given time, even when many clients are concurrently making requests of the actor. As part of the Swift Concurrency Model, actors provide the same race and memory safety properties as structured concurrency, but provide the familiar abstraction and reuse features that other explicitly declared types in Swift enjoy…

This thread was posted by one of our members via one of our news source trackers.