pollster-0.4.0/.cargo_vcs_info.json0000644000000001360000000000100127010ustar { "git": { "sha1": "2864daf5febd81eb33f66cb32b66ca78a9e21db7" }, "path_in_vcs": "" }pollster-0.4.0/.github/FUNDING.yml000064400000000000000000000000231046102023000146410ustar 00000000000000github: [zesterer] pollster-0.4.0/.github/workflows/rust.yml000064400000000000000000000015671046102023000166170ustar 00000000000000name: Rust on: push: branches: [ master ] pull_request: branches: [ master ] env: CARGO_TERM_COLOR: always jobs: build: runs-on: ubuntu-latest steps: - uses: actions/checkout@v3 - name: Build run: cargo build --verbose - name: Run tests run: cargo test --verbose build-with-macro: runs-on: ubuntu-latest steps: - uses: actions/checkout@v3 - name: Build run: cargo build --features macro --verbose - name: Run tests run: cargo test --features macro --verbose msrv: name: MSRV runs-on: ubuntu-latest steps: - uses: actions/checkout@v3 - name: Install MSRV uses: dtolnay/rust-toolchain@master with: toolchain: "1.69" components: rustfmt, clippy - name: Check MSRV compatibility run: cargo check --verbose --all-features pollster-0.4.0/.gitignore000064400000000000000000000000231046102023000134540ustar 00000000000000Cargo.lock target/*pollster-0.4.0/CHANGELOG.md000064400000000000000000000013431046102023000133030ustar 00000000000000# Changelog All notable changes to this project will be documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html). # Unreleased ### Added ### Removed ### Changed ### Fixed # [0.4.0] - 2024-10-26 ### Added - MSRV policy ### Removed - All `unsafe` code ### Changed - Updated MSRV to 1.69 - `block_on` now accepts `IntoFuture` instead of `Future` (this is a backward-compatible change) # [0.3.0] - 2023-02-07 ### Added - `pollster::main` and `pollster::test` procedural macros, akin to `tokio::main` and `tokio::test` ### Changed - Improved performance by removing unnecessary allocation pollster-0.4.0/Cargo.toml0000644000000023150000000000100107000ustar # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies. # # If you are reading this file be aware that the original Cargo.toml # will likely look very different (and much more reasonable). # See Cargo.toml.orig for the original contents. [package] edition = "2018" name = "pollster" version = "0.4.0" authors = ["Joshua Barretto "] description = "Synchronously block the thread until a future completes" readme = "README.md" keywords = [ "async", "minimal", "executor", "runtime", "block_on", ] categories = [ "asynchronous", "concurrency", ] license = "Apache-2.0/MIT" repository = "https://github.com/zesterer/pollster" [package.metadata.docs.rs] all-features = true rustdoc-args = [ "--cfg", "docsrs", ] targets = [] [dependencies.pollster-macro] version = "0.4.0" optional = true [dev-dependencies.futures-timer] version = "3.0" [dev-dependencies.tokio] version = "1" features = ["sync"] [features] macro = ["pollster-macro"] pollster-0.4.0/Cargo.toml.orig000064400000000000000000000014201046102023000143550ustar 00000000000000[workspace] members = ["", "macro"] default-members = ["macro"] [package] name = "pollster" version = "0.4.0" description = "Synchronously block the thread until a future completes" categories = ["asynchronous", "concurrency"] keywords = ["async", "minimal", "executor", "runtime", "block_on"] repository = "https://github.com/zesterer/pollster" authors = ["Joshua Barretto "] edition = "2018" license = "Apache-2.0/MIT" readme = "README.md" [features] macro = ["pollster-macro"] [dependencies] pollster-macro = { version = "0.4.0", path = "macro", optional = true } [dev-dependencies] futures-timer = "3.0" tokio = { version = "1", features = ["sync"] } [package.metadata.docs.rs] all-features = true targets = [] rustdoc-args = ["--cfg", "docsrs"] pollster-0.4.0/LICENSE-APACHE000064400000000000000000000251371046102023000134250ustar 00000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. pollster-0.4.0/LICENSE-MIT000064400000000000000000000020501046102023000131220ustar 00000000000000Copyright (c) 2020-2021 Joshua Barretto Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. pollster-0.4.0/README.md000064400000000000000000000066301046102023000127550ustar 00000000000000# Pollster Pollster is an incredibly minimal async executor for Rust that lets you block a thread until a future completes. [![Cargo](https://img.shields.io/crates/v/pollster.svg)]( https://crates.io/crates/pollster) [![Documentation](https://docs.rs/pollster/badge.svg)]( https://docs.rs/pollster) [![License](https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg)]( https://github.com/zesterer/pollster) ![actions-badge](https://github.com/zesterer/pollster/workflows/Rust/badge.svg?branch=master) ```rust use pollster::FutureExt as _; let my_fut = async {}; let result = my_fut.block_on(); ``` That's it. That's all it does. Nothing more, nothing less. No need to pull in 50 crates to evaluate a future. ## Why is this useful? Now that `async` functions are stable, we're increasingly seeing libraries all over the Rust ecosystem expose `async` APIs. This is great for those wanting to build highly concurrent web applications! However, many of us are *not* building highly concurrent web applications, but end up faced with an `async` function that we can't easily call from synchronous code. If you're in this position, then `pollster` is for you: it allows you to evaluate a future in-place without spinning up a heavyweight runtime like `tokio` or `async_std`. ## Minimalism Pollster is built with the [UNIX ethos](https://en.wikipedia.org/wiki/Unix_philosophy#Do_One_Thing_and_Do_It_Well) in mind: do one thing, and do it well. It has no dependencies, compiles quickly, and is composed of only ~100 lines of well-audited code. ## Behaviour Pollster will synchronously block the thread until a future completes. It will not spin: instead, it will place the thread into a waiting state until the future has been polled to completion. ## Compatibility Unfortunately, `pollster` will not work for *all* futures because some require a specific runtime or reactor. See [here](https://rust-lang.github.io/async-book/08_ecosystem/00_chapter.html#determining-ecosystem-compatibility) for more information about when and where `pollster` may be used. However, if you're already pulling in the required dependencies to create such a future in the first place, it's likely that you already have a version of `block_on` in your dependency tree that's designed to poll your future, so use that instead. ## Macro When using the `macro` crate feature, an attribute-macro can be used to mark `async fn main()`: ```rust,ignore #[pollster::main] async fn main() { let my_fut = async {}; my_fut.await; } ``` Additionally if you have re-exported the crate with a different name then `pollster`, you have to specify it: ```rust,ignore #[pollster::main(crate = renamed_pollster)] async fn main() { let my_fut = async {}; my_fut.await; } ``` You can also use `#[pollster::test]` for tests. ## Comparison with `futures::executor::block_on` `pollster` does approximately the same thing as the `block_on` function from the `futures` crate. If you already have `futures` in your dependency tree, you might as well use it instead. `pollster` is primarily for applications that don't care to pull all of `futures` or another runtime like `tokio` into their dependency tree for the sake of evaluating simple futures. ## Minimum Supported Rust Version (MSRV) Policy Current MSRV: `1.69.0` `pollster` has a policy of supporting compiler versions that are at least 18 months old. The crate *may* compile with older compilers, but this is not guaranteed. pollster-0.4.0/src/lib.rs000064400000000000000000000106551046102023000134030ustar 00000000000000#![doc = include_str!("../README.md")] #![cfg_attr(docsrs, feature(doc_auto_cfg))] use std::{ future::{Future, IntoFuture}, sync::{Arc, Condvar, Mutex}, task::{Context, Poll, Wake, Waker}, }; #[cfg(feature = "macro")] pub use pollster_macro::{main, test}; /// An extension trait that allows blocking on a future in suffix position. pub trait FutureExt: Future { /// Block the thread until the future is ready. /// /// # Example /// /// ``` /// use pollster::FutureExt as _; /// /// let my_fut = async {}; /// /// let result = my_fut.block_on(); /// ``` fn block_on(self) -> Self::Output where Self: Sized { block_on(self) } } impl FutureExt for F {} enum SignalState { Empty, Waiting, Notified, } struct Signal { state: Mutex, cond: Condvar, } impl Signal { fn new() -> Self { Self { state: Mutex::new(SignalState::Empty), cond: Condvar::new(), } } fn wait(&self) { let mut state = self.state.lock().unwrap(); match *state { // Notify() was called before we got here, consume it here without waiting and return immediately. SignalState::Notified => *state = SignalState::Empty, // This should not be possible because our signal is created within a function and never handed out to any // other threads. If this is the case, we have a serious problem so we panic immediately to avoid anything // more problematic happening. SignalState::Waiting => { unreachable!("Multiple threads waiting on the same signal: Open a bug report!"); } SignalState::Empty => { // Nothing has happened yet, and we're the only thread waiting (as should be the case!). Set the state // accordingly and begin polling the condvar in a loop until it's no longer telling us to wait. The // loop prevents incorrect spurious wakeups. *state = SignalState::Waiting; while let SignalState::Waiting = *state { state = self.cond.wait(state).unwrap(); } } } } fn notify(&self) { let mut state = self.state.lock().unwrap(); match *state { // The signal was already notified, no need to do anything because the thread will be waking up anyway SignalState::Notified => {} // The signal wasn't notified but a thread isn't waiting on it, so we can avoid doing unnecessary work by // skipping the condvar and leaving behind a message telling the thread that a notification has already // occurred should it come along in the future. SignalState::Empty => *state = SignalState::Notified, // The signal wasn't notified and there's a waiting thread. Reset the signal so it can be wait()'ed on again // and wake up the thread. Because there should only be a single thread waiting, `notify_all` would also be // valid. SignalState::Waiting => { *state = SignalState::Empty; self.cond.notify_one(); } } } } impl Wake for Signal { fn wake(self: Arc) { self.notify(); } fn wake_by_ref(self: &Arc) { self.notify(); } } /// Block the thread until the future is ready. /// /// # Example /// /// ``` /// let my_fut = async {}; /// let result = pollster::block_on(my_fut); /// ``` pub fn block_on(fut: F) -> F::Output { let mut fut = core::pin::pin!(fut.into_future()); // Signal used to wake up the thread for polling as the future moves to completion. We need to use an `Arc` // because, although the lifetime of `fut` is limited to this function, the underlying IO abstraction might keep // the signal alive for far longer. `Arc` is a thread-safe way to allow this to happen. // TODO: Investigate ways to reuse this `Arc`... perhaps via a `static`? let signal = Arc::new(Signal::new()); // Create a context that will be passed to the future. let waker = Waker::from(Arc::clone(&signal)); let mut context = Context::from_waker(&waker); // Poll the future to completion loop { match fut.as_mut().poll(&mut context) { Poll::Pending => signal.wait(), Poll::Ready(item) => break item, } } } pollster-0.4.0/tests/basic.rs000064400000000000000000000027031046102023000142640ustar 00000000000000use std::time::{Duration, Instant}; #[test] fn basic() { let make_fut = || std::future::ready(42); // Immediately ready assert_eq!(pollster::block_on(make_fut()), 42); // Ready after a timeout let then = Instant::now(); pollster::block_on(futures_timer::Delay::new(Duration::from_millis(250))); assert!(Instant::now().duration_since(then) > Duration::from_millis(250)); } #[test] fn mpsc() { use std::{ sync::atomic::{AtomicUsize, Ordering::SeqCst}, thread, }; use tokio::sync::mpsc; const BOUNDED: usize = 16; const MESSAGES: usize = 100_000; let (a_tx, mut a_rx) = mpsc::channel(BOUNDED); let (b_tx, mut b_rx) = mpsc::channel(BOUNDED); let thread_a = thread::spawn(move || { pollster::block_on(async { while let Some(msg) = a_rx.recv().await { b_tx.send(msg).await.expect("send on b"); } }); }); let thread_b = thread::spawn(move || { pollster::block_on(async move { for _ in 0..MESSAGES { a_tx.send(()).await.expect("Send on a"); } }); }); pollster::block_on(async move { let sum = AtomicUsize::new(0); while sum.fetch_add(1, SeqCst) < MESSAGES { b_rx.recv().await; } assert_eq!(sum.load(SeqCst), MESSAGES + 1); }); thread_a.join().expect("join thread_a"); thread_b.join().expect("join thread_b"); }