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//! The Fibers module. //! //! **NOTE** A Drone platform crate may re-export this module with its own //! additions under the same name, in which case it should be used instead. //! //! A fiber is a task unit of Drone. It is a stack-less co-routine programmed //! with async/await, generator, or closure Rust syntaxes. Any number of fibers //! can be added to a particular thread. A thread executes its fibers in LIFO //! order. When a fiber yields, the thread keeps it for the next time it resumes //! and proceeds to the next fiber. When a fiber returns, the thread drops it //! and proceeds to the next fiber. When there are no fibers left, the thread //! suspends. //! //! # Basic Fibers //! //! A basic fiber can be created with [`fib::new`], [`fib::new_fn`], or //! [`fib::new_once`]: //! //! ``` //! # #![feature(generators)] //! use drone_core::fib; //! //! // A fiber based on a generator. //! // This is `impl Fiber<Input = (), Yield = i32, Return = i32>` //! let a = fib::new(|| { //! // do some work and yield //! yield 1; //! // do some work and yield //! yield 2; //! // do some work and return //! 3 //! }); //! //! // A fiber based on an `FnMut` closure. //! // This is `impl Fiber<Input = (), Yield = i32, Return = i32>` //! let b = fib::new_fn(|| { //! // check some condition //! if true { //! // do some work and yield //! fib::Yielded(1) //! } else { //! // do some work and return //! fib::Complete(2) //! } //! }); //! //! // A fiber based on an `FnOnce` closure. //! // This is `impl Fiber<Input = (), Yield = !, Return = i32>` //! let c = fib::new_once(|| { //! // do some work and immediately return //! 4 //! }); //! ``` //! //! A basic fiber can be attached to a thread with //! [`token.add(...)`](fib::ThrFiberGen::add), //! [`token.add_fn(...)`](fib::ThrFiberClosure::add_fn), or //! [`token.add_once(...)`](fib::ThrFiberClosure::add_once). Note that fibers //! that are directly attached to threads can't have yield and return values //! other than `()` or `!`. //! //! ``` //! # #![feature(generators)] //! # #![feature(never_type)] //! # use drone_core::token::Token; //! # static mut THREADS: [Thr; 1] = [Thr::new(0)]; //! # drone_core::thr!(use THREADS; struct Thr {} struct ThrLocal {}); //! # #[derive(Clone, Copy)] struct SysTick; //! # struct Thrs { sys_tick: SysTick } //! # unsafe impl Token for Thrs { //! # unsafe fn take() -> Self { Self { sys_tick: SysTick::take() } } //! # } //! # unsafe impl Token for SysTick { //! # unsafe fn take() -> Self { Self } //! # } //! # unsafe impl drone_core::thr::ThrToken for SysTick { //! # type Thr = Thr; //! # const THR_NUM: usize = 0; //! # } //! # fn main() { //! # let thr = unsafe { Thrs::take() }; //! use drone_core::{fib, thr::prelude::*}; //! //! // A fiber based on a generator. //! // This is `impl Fiber<Input = (), Yield = (), Return = ()>` //! thr.sys_tick.add(|| { //! // do some work and yield //! yield; //! // do some work and yield //! yield; //! // do some work and return //! }); //! //! // A fiber based on an `FnMut` closure. //! // This is `impl Fiber<Input = (), Yield = (), Return = !>` //! thr.sys_tick.add_fn(|| { //! // do some work and yield //! fib::Yielded::<(), !>(()) //! }); //! //! // A fiber based on an `FnOnce` closure. //! // This is `impl Fiber<Input = (), Yield = !, Return = ()>` //! thr.sys_tick.add_once(|| { //! // do some work and immediately return //! }); //! # } //! ``` //! //! # Compound Fibers //! //! There is a number of useful compound fibers implemented in this module: //! //! | Method | Input / Output | //! |------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------| //! | [`token.add_future(...)`](fib::ThrFiberFuture::add_future) | `Fiber<Input = (), Yield = ()/!, Return = T>` | //! | `->` | `Future<Output = T>` | //! | [`token.add_stream_pulse(...)`](fib::ThrFiberStreamPulse::add_stream_pulse) | `Fiber<Input = (), Yield = Option<usize>, Return = Result<Option<usize>, E>>` | //! | `->` | `Stream<Item = Result<NonZeroUsize, E>>` | //! | [`token.add_stream_pulse_skip(...)`](fib::ThrFiberStreamPulse::add_stream_pulse_skip) | `Fiber<Input = (), Yield = Option<usize>, Return = Option<usize>>` | //! | `->` | `Stream<Item = NonZeroUsize>` | //! | [`token.add_stream_ring(...)`](fib::ThrFiberStreamRing::add_stream_ring) | `Fiber<Input = (), Yield = Option<T>, Return = Result<Option<T>, E>>` | //! | `->` | `Stream<Item = Result<T, E>>` | //! | [`token.add_stream_ring_skip(...)`](fib::ThrFiberStreamRing::add_stream_ring_skip) | `Fiber<Input = (), Yield = Option<T>, Return = Option<T>>` | //! | `->` | `Stream<Item = T>` | //! | [`token.add_stream_ring_overwrite(...)`](fib::ThrFiberStreamRing::add_stream_ring_overwrite) | `Fiber<Input = (), Yield = Option<T>, Return = Option<T>>` | //! | `->` | `Stream<Item = T>` | //! | [`token.add_try_stream_ring_overwrite(...)`](fib::ThrFiberStreamRing::add_try_stream_ring_overwrite) | `Fiber<Input = (), Yield = Option<T>, Return = Result<Option<T>, E>>` | //! | `->` | `Stream<Item = Result<T, E>>` | //! //! ## Examples //! //! ``` //! # #![feature(generators)] //! # use drone_core::token::Token; //! # static mut THREADS: [Thr; 1] = [Thr::new(0)]; //! # drone_core::thr!(use THREADS; struct Thr {} struct ThrLocal {}); //! # #[derive(Clone, Copy)] struct SysTick; //! # struct Thrs { sys_tick: SysTick } //! # unsafe impl Token for Thrs { //! # unsafe fn take() -> Self { Self { sys_tick: SysTick::take() } } //! # } //! # unsafe impl Token for SysTick { //! # unsafe fn take() -> Self { Self } //! # } //! # unsafe impl drone_core::thr::ThrToken for SysTick { //! # type Thr = Thr; //! # const THR_NUM: usize = 0; //! # } //! # fn main() { //! # let thr = unsafe { Thrs::take() }; //! # async { //! use drone_core::{fib, thr::prelude::*}; //! //! let a = thr.sys_tick.add_future(fib::new(|| { //! yield; //! yield; //! 123 //! })); //! //! // `b` will have the value of 123 after the SYS_TICK thread has triggered 3 //! // times. //! let b = a.await; //! # }; //! # } //! ``` mod chain; mod closure; mod future; mod generator; mod stream_pulse; mod stream_ring; pub use self::{ chain::Chain, closure::{new_fn, new_once, FiberFn, FiberOnce, ThrFiberClosure}, future::{FiberFuture, ThrFiberFuture}, generator::{new, FiberGen, ThrFiberGen}, stream_pulse::{FiberStreamPulse, ThrFiberStreamPulse, TryFiberStreamPulse}, stream_ring::{FiberStreamRing, ThrFiberStreamRing, TryFiberStreamRing}, }; pub use FiberState::*; use core::pin::Pin; /// The main task unit of Drone. pub trait Fiber { /// The type of value this fiber consumes on each [`resume`](Fiber::resume). type Input; /// The type of value this fiber yields. type Yield; /// The type of value this fiber returns on completion. type Return; /// Resumes the execution of this fiber. /// /// This method will resume execution of the fiber or start execution if it /// hasn't already. /// /// # Return value /// /// The [`FiberState`] enum returned from this method indicates what state /// the fiber is in upon returning. If [`FiberState::Yielded`] is returned /// then the fiber has reached a suspension point and a value has been /// yielded out. Fibers in this state are available for resumption on a /// later point. /// /// If [`FiberState::Complete`] is returned then the fiber has completely /// finished with the value provided. It is invalid for the fiber to be /// resumed again. /// /// # Panics /// /// This method may panic if it is called after [`FiberState::Complete`] has /// been returned previously. fn resume(self: Pin<&mut Self>, input: Self::Input) -> FiberState<Self::Yield, Self::Return>; } /// The root fiber trait. /// /// A variation of [`Fiber`] with `Input` being `()`, `Yield` - `()` or `!`, /// `Complete` - `()`. pub trait FiberRoot: Send + 'static { /// Resumes the execution of this fiber. /// /// This method will resume execution of the fiber or start execution if it /// hasn't already. /// /// # Return value /// /// If `true` is returned then the fiber has reached a suspension /// point. Fibers in this state are available for resumption on a later /// point. /// /// If `false` is returned then the fiber has completely finished. It is /// invalid for the fiber to be resumed again. /// /// # Panics /// /// This method may panic if it is called after `false` has been returned /// previously. fn advance(self: Pin<&mut Self>) -> bool; } /// The result of a fiber resumption. /// /// The enum is returned from the [`Fiber::resume`] method and indicates the /// possible return value of a fiber. #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)] pub enum FiberState<Y, R> { /// The fiber suspended with a value. Yielded(Y), /// The fiber completed with a return value. Complete(R), } impl<Y, R> FiberState<Y, R> { /// Returns `true` if this is [`FiberState::Yielded`]. #[inline] pub fn is_yielded(&self) -> bool { match self { FiberState::Yielded(_) => true, FiberState::Complete(_) => false, } } /// Returns `true` if this is [`FiberState::Complete`]. #[inline] pub fn is_complete(&self) -> bool { match self { FiberState::Yielded(_) => false, FiberState::Complete(_) => true, } } }