├── .github └── workflows │ └── ci.yml ├── .gitignore ├── CHANGELOG.md ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md ├── bors.toml ├── src └── lib.rs └── tests └── futures.rs /.github/workflows/ci.yml: -------------------------------------------------------------------------------- 1 | on: 2 | push: 3 | branches: 4 | - master 5 | - staging 6 | - trying 7 | pull_request: 8 | 9 | name: CI 10 | 11 | jobs: 12 | tests: 13 | runs-on: ubuntu-latest 14 | strategy: 15 | matrix: 16 | rust: 17 | - stable 18 | - beta 19 | steps: 20 | - uses: actions/checkout@v3 21 | 22 | - uses: dtolnay/rust-toolchain@v1 23 | with: 24 | toolchain: ${{ matrix.rust }} 25 | components: rustfmt, clippy 26 | 27 | - run: cargo build --all-targets 28 | - run: cargo test 29 | - run: cargo fmt --all -- --check 30 | - run: cargo clippy --all-targets -- -D warnings 31 | 32 | # Reduced build for the Minimum Supported Rust Version. It does not include the lints as some of 33 | # them are out-of-date and result in false positives on the codebase, e.g. mutex_atomic. 34 | msrv: 35 | name: MSRV 36 | runs-on: ubuntu-latest 37 | steps: 38 | - uses: actions/checkout@v3 39 | 40 | - uses: dtolnay/rust-toolchain@v1 41 | with: 42 | toolchain: "1.68" 43 | 44 | - run: cargo test 45 | 46 | miri: 47 | name: Miri 48 | runs-on: ubuntu-latest 49 | 50 | steps: 51 | - uses: actions/checkout@v3 52 | 53 | - uses: dtolnay/rust-toolchain@v1 54 | with: 55 | toolchain: nightly 56 | components: miri, rust-src 57 | 58 | - run: cargo miri test 59 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | /target 2 | /Cargo.lock 3 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | # Changelog 2 | All notable changes to this project will be documented in this file. 3 | 4 | The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), 5 | and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). 6 | 7 | ## [Unreleased] 8 | 9 | ## [1.0.0] - 2023-04-17 10 | 11 | ### Changed 12 | 13 | - Use dynamic dispatch internally to save on code gen. External API unchanged. 14 | - No longer heap-allocate futures. 15 | 16 | ### Breaking 17 | 18 | - Minimum supported Rust version bumped to 1.68. 19 | 20 | ## [0.1.1] - 2022-09-05 21 | 22 | ### Fixed 23 | 24 | - Fixed potential hanging when the waker is called while polling. 25 | 26 | ## [0.1.0] - 2022-09-01 27 | 28 | - Initial release 29 | 30 | [Unreleased]: https://github.com/bertptrs/beul/compare/v1.0.0...HEAD 31 | [1.0.0]: https://github.com/bertptrs/beul/compare/v0.1.1...v1.0.0 32 | [0.1.1]: https://github.com/bertptrs/beul/compare/v0.1.0...v0.1.1 33 | [0.1.0]: https://github.com/bertptrs/beul/releases/tag/v0.1.0 34 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "beul" 3 | version = "1.0.0" 4 | edition = "2021" 5 | license = "MIT OR Apache-2.0" 6 | description = "It executes futures" 7 | repository = "https://github.com/bertptrs/beul/" 8 | rust-version = "1.68" 9 | authors = [ 10 | "Bert Peters", 11 | ] 12 | categories = [ 13 | "asynchronous", 14 | "development-tools", 15 | ] 16 | keywords = [ 17 | "futures", 18 | "async", 19 | "executor", 20 | "runtime", 21 | ] 22 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | 2 | Apache License 3 | Version 2.0, January 2004 4 | http://www.apache.org/licenses/ 5 | 6 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 7 | 8 | 1. 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IN NO EVENT SHALL THE 18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 | SOFTWARE. 22 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Beul 2 | 3 | Beul is a minimalistic futures executor. No dependencies, no unsafe rust. It simply executes 4 | futures. 5 | 6 | "Beul" is Dutch for executioner. It's a pun. 7 | 8 | ## Usage 9 | 10 | Simply call `execute` with your future: 11 | 12 | ```rust 13 | beul::execute(async {}); 14 | ``` 15 | 16 | ### Backwards compatibility 17 | 18 | This crate requires at least Rust 1.68, due to its reliance on [std::pin::pin!]. Increases in this 19 | version will be considered breaking changes and will be avoided if possible. The minimum supported 20 | Rust version will only be bumped in major or minor versions. This crate follows semantic versioning. 21 | 22 | ### Limitations 23 | 24 | Beul is a single-threaded executor and will not provide anything but execution. Futures that depend 25 | on runtime features, as present for example in [Tokio], will not work. 26 | 27 | ## License 28 | 29 | Licensed under either of 30 | 31 | * Apache License, Version 2.0 ([LICENSE-APACHE](./LICENSE-APACHE) or 32 | http://www.apache.org/licenses/LICENSE-2.0) 33 | * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) 34 | 35 | at your option. 36 | 37 | ### Contribution 38 | 39 | Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the 40 | work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any 41 | additional terms or conditions. 42 | 43 | [Tokio]: https://tokio.rs/ 44 | [std::pin::pin!]: https://doc.rust-lang.org/std/pin/macro.pin.html 45 | -------------------------------------------------------------------------------- /bors.toml: -------------------------------------------------------------------------------- 1 | status = [ 2 | 'MSRV', 3 | 'tests (stable)', 4 | 'tests (beta)', 5 | 'Miri', 6 | ] 7 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | //! Beul - It executes futures. 2 | //! 3 | //! This crate offers a single function: [`execute`], which will run a single future on the current 4 | //! thread. No fancy executor, no future primitives, just a simple executor. No dependencies, no 5 | //! unsafe rust. 6 | //! 7 | //! The design is based on the example `ThreadWaker` from the [`Wake`] documentation, which the 8 | //! reentrancy issues resolved by using a [`Condvar`]. 9 | //! 10 | //! Beul is Dutch for executioner. 11 | //! 12 | //! # Usage 13 | //! 14 | //! ``` 15 | //! beul::execute(async {}); 16 | //! ``` 17 | #![forbid(unsafe_code)] 18 | use std::future::Future; 19 | use std::pin::Pin; 20 | use std::sync::Arc; 21 | use std::sync::Condvar; 22 | use std::sync::Mutex; 23 | use std::sync::PoisonError; 24 | use std::task::Context; 25 | use std::task::Poll; 26 | use std::task::Wake; 27 | use std::task::Waker; 28 | 29 | #[derive(Default)] 30 | struct CondvarWake { 31 | park: Condvar, 32 | awoken: Mutex, 33 | } 34 | 35 | impl CondvarWake { 36 | pub fn park(&self) { 37 | let mut guard = self.awoken.lock().unwrap_or_else(PoisonError::into_inner); 38 | 39 | // Until we are awoken, we can park on the condvar. This also handles the case where we're 40 | // awoken while we're actually polling. 41 | while !*guard { 42 | guard = self 43 | .park 44 | .wait(guard) 45 | .unwrap_or_else(PoisonError::into_inner); 46 | } 47 | 48 | *guard = false; 49 | } 50 | } 51 | 52 | impl Wake for CondvarWake { 53 | fn wake(self: Arc) { 54 | self.wake_by_ref() 55 | } 56 | 57 | fn wake_by_ref(self: &Arc) { 58 | *self.awoken.lock().unwrap_or_else(PoisonError::into_inner) = true; 59 | self.park.notify_one(); 60 | } 61 | } 62 | 63 | /// Block on specified [`Future`]. 64 | /// 65 | /// The future will be polled until completion on the current thread. 66 | pub fn execute(f: impl Future) -> T { 67 | // Use dynamic dispatch to save on codegen 68 | poll(std::pin::pin!(f)) 69 | } 70 | 71 | /// Poll a future until completion. 72 | fn poll(mut pinned: Pin<&mut dyn Future>) -> T { 73 | let wake = Arc::new(CondvarWake::default()); 74 | let waker = Waker::from(Arc::clone(&wake)); 75 | 76 | let mut context = Context::from_waker(&waker); 77 | 78 | loop { 79 | match pinned.as_mut().poll(&mut context) { 80 | Poll::Ready(value) => return value, 81 | Poll::Pending => wake.park(), 82 | } 83 | } 84 | } 85 | -------------------------------------------------------------------------------- /tests/futures.rs: -------------------------------------------------------------------------------- 1 | use std::future::Future; 2 | use std::sync::atomic::AtomicBool; 3 | use std::sync::atomic::Ordering; 4 | use std::sync::Arc; 5 | use std::task::Context; 6 | use std::task::Poll; 7 | use std::thread; 8 | 9 | #[test] 10 | fn test_simple() { 11 | // Sanity check 12 | assert_eq!(42, beul::execute(async { 42 })); 13 | 14 | // Some more esoteric futures 15 | beul::execute(async { async {}.await }); 16 | beul::execute(async { beul::execute(async {}) }); 17 | } 18 | 19 | #[test] 20 | fn test_threaded_future() { 21 | /// Dummy future that sleeps until a separate thread wakes it 22 | /// 23 | /// It returns the number of times it has been awoken 24 | struct ThreadedFuture(Arc, usize); 25 | 26 | impl Future for ThreadedFuture { 27 | type Output = usize; 28 | 29 | fn poll(mut self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { 30 | // Note down that we've been polled 31 | self.1 += 1; 32 | 33 | if self.0.load(Ordering::Acquire) { 34 | Poll::Ready(self.1) 35 | } else { 36 | if self.1 == 1 { 37 | let completer = Arc::clone(&self.0); 38 | let waker = cx.waker().clone(); 39 | thread::spawn(move || { 40 | completer.store(true, Ordering::Release); 41 | waker.wake(); 42 | }); 43 | } 44 | 45 | Poll::Pending 46 | } 47 | } 48 | } 49 | 50 | let future = ThreadedFuture(Arc::new(AtomicBool::new(false)), 0); 51 | 52 | // Future should be polled twice, once initially and once after the wake-up 53 | assert_eq!(beul::execute(future), 2); 54 | } 55 | 56 | #[test] 57 | fn test_self_waking_futures() { 58 | struct SelfWakingFuture(bool); 59 | 60 | impl Future for SelfWakingFuture { 61 | type Output = (); 62 | 63 | fn poll(mut self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll { 64 | if self.0 { 65 | Poll::Ready(()) 66 | } else { 67 | // Next time we complete 68 | self.0 = true; 69 | // Request to be woken up 70 | cx.waker().wake_by_ref(); 71 | 72 | Poll::Pending 73 | } 74 | } 75 | } 76 | 77 | beul::execute(SelfWakingFuture(false)); 78 | } 79 | --------------------------------------------------------------------------------