From dc66c0665e86d55ab91a63b7d5a218b21fe5a98c Mon Sep 17 00:00:00 2001 From: Stjepan Glavina Date: Sun, 17 May 2020 17:41:54 +0200 Subject: [PATCH] Initial commit --- .github/FUNDING.yml | 1 + .github/workflows/build-and-test.yaml | 51 +++++++ .github/workflows/lint.yaml | 26 ++++ .github/workflows/security.yaml | 20 +++ .gitignore | 2 + CHANGELOG.md | 3 + Cargo.toml | 19 +++ LICENSE-APACHE | 201 ++++++++++++++++++++++++ LICENSE-MIT | 23 +++ README.md | 57 +++++++ src/lib.rs | 212 ++++++++++++++++++++++++++ 11 files changed, 615 insertions(+) create mode 100644 .github/FUNDING.yml create mode 100644 .github/workflows/build-and-test.yaml create mode 100644 .github/workflows/lint.yaml create mode 100644 .github/workflows/security.yaml create mode 100644 .gitignore create mode 100644 CHANGELOG.md create mode 100644 Cargo.toml create mode 100644 LICENSE-APACHE create mode 100644 LICENSE-MIT create mode 100644 README.md create mode 100644 src/lib.rs diff --git a/.github/FUNDING.yml b/.github/FUNDING.yml new file mode 100644 index 0000000..e1f75e7 --- /dev/null +++ b/.github/FUNDING.yml @@ -0,0 +1 @@ +github: stjepang diff --git a/.github/workflows/build-and-test.yaml b/.github/workflows/build-and-test.yaml new file mode 100644 index 0000000..fd7598b --- /dev/null +++ b/.github/workflows/build-and-test.yaml @@ -0,0 +1,51 @@ +name: Build and test + +on: + push: + branches: + - master + pull_request: + +jobs: + build_and_test: + runs-on: ${{ matrix.os }} + strategy: + fail-fast: false + matrix: + os: [ubuntu-latest] + rust: [nightly, beta, stable] + steps: + - uses: actions/checkout@v2 + + - name: Set current week of the year in environnement + if: startsWith(matrix.os, 'ubuntu') || startsWith(matrix.os, 'macOS') + run: echo "::set-env name=CURRENT_WEEK::$(date +%V)" + + - name: Set current week of the year in environnement + if: startsWith(matrix.os, 'windows') + run: echo "::set-env name=CURRENT_WEEK::$(Get-Date -UFormat %V)" + + - name: Install latest ${{ matrix.rust }} + uses: actions-rs/toolchain@v1 + with: + toolchain: ${{ matrix.rust }} + profile: minimal + override: true + + - name: Run cargo check + uses: actions-rs/cargo@v1 + with: + command: check + args: --all --benches --bins --examples --tests --all-features + + - name: Run cargo check (without dev-dependencies to catch missing feature flags) + if: startsWith(matrix.rust, 'nightly') + uses: actions-rs/cargo@v1 + with: + command: check + args: -Z features=dev_dep + + - name: Run cargo test + uses: actions-rs/cargo@v1 + with: + command: test diff --git a/.github/workflows/lint.yaml b/.github/workflows/lint.yaml new file mode 100644 index 0000000..7e9bd98 --- /dev/null +++ b/.github/workflows/lint.yaml @@ -0,0 +1,26 @@ +name: Lint + +on: + push: + branches: + - master + pull_request: + +jobs: + clippy: + runs-on: ubuntu-latest + steps: + - uses: actions/checkout@v2 + + - name: Set current week of the year in environnement + run: echo "::set-env name=CURRENT_WEEK::$(date +%V)" + + - uses: actions-rs/toolchain@v1 + with: + toolchain: stable + profile: minimal + components: clippy + - uses: actions-rs/clippy-check@v1 + with: + token: ${{ secrets.GITHUB_TOKEN }} + args: --all-features -- -W clippy::all diff --git a/.github/workflows/security.yaml b/.github/workflows/security.yaml new file mode 100644 index 0000000..8f722e7 --- /dev/null +++ b/.github/workflows/security.yaml @@ -0,0 +1,20 @@ +name: Security audit + +on: + push: + branches: + - master + pull_request: + +jobs: + security_audit: + runs-on: ubuntu-latest + steps: + - uses: actions/checkout@v2 + + - name: Set current week of the year in environnement + run: echo "::set-env name=CURRENT_WEEK::$(date +%V)" + + - uses: actions-rs/audit-check@v1 + with: + token: ${{ secrets.GITHUB_TOKEN }} diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..96ef6c0 --- /dev/null +++ b/.gitignore @@ -0,0 +1,2 @@ +/target +Cargo.lock diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 index 0000000..af42cea --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,3 @@ +# Version 1.0.0 + +- Initial version diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..226ab9d --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,19 @@ +[package] +name = "async-lock" +version = "1.0.0" +authors = ["Stjepan Glavina "] +edition = "2018" +description = "Reference-counted async lock" +license = "Apache-2.0 OR MIT" +repository = "https://github.com/stjepang/async-lock" +homepage = "https://github.com/stjepang/async-lock" +documentation = "https://docs.rs/async-lock" +keywords = ["async", "file", "stdio", "stdin", "process"] +categories = ["asynchronous", "concurrency"] +readme = "README.md" + +[dependencies] +event-listener = "1.0.0" + +[dev-dependencies] +smol = "0.1.6" diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..16fe87b --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,201 @@ + 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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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. diff --git a/README.md b/README.md new file mode 100644 index 0000000..213537b --- /dev/null +++ b/README.md @@ -0,0 +1,57 @@ +# async-lock + +[![Build](https://github.com/stjepang/async-lock/workflows/Build%20and%20test/badge.svg)]( +https://github.com/stjepang/async-lock/actions) +![Rustc version](https://img.shields.io/badge/rustc-1.40+-lightgray.svg) +[![License](https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg)]( +https://github.com/stjepang/async-lock) +[![Cargo](https://img.shields.io/crates/v/async-lock.svg)]( +https://crates.io/crates/async-lock) +[![Documentation](https://docs.rs/async-lock/badge.svg)]( +https://docs.rs/async-lock) + +Reference-counted async lock. + +The `Lock` type is similar to `std::sync::Mutex`, except locking is an async operation. + +Note that `Lock` by itself acts like an `Arc` in the sense that cloning it returns just +another reference to the same lock. + +Furthermore, `LockGuard` is not tied to `Lock` by a lifetime, so you can keep guards for +as long as you want. This is useful when you want to spawn a task and move a guard into its +future. + +## Examples + +```rust +use async_lock::Lock; +use smol::Task; + +let lock = Lock::new(0); +let mut tasks = vec![]; + +for _ in 0..10 { + let lock = lock.clone(); + tasks.push(Task::spawn(async move { *lock.lock().await += 1 })); +} + +for task in tasks { + task.await; +} +assert_eq!(*lock.lock().await, 10); +``` + +## License + +Licensed under either of + + * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) + * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) + +at your option. + +#### Contribution + +Unless you explicitly state otherwise, any contribution intentionally submitted +for inclusion in the work by you, as defined in the Apache-2.0 license, shall be +dual licensed as above, without any additional terms or conditions. diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..3a5d382 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,212 @@ +//! Reference-counted async lock. +//! +//! The [`Lock`] type is similar to [`std::sync::Mutex`], except locking is an async operation. +//! +//! Note that [`Lock`] by itself acts like an [`Arc`] in the sense that cloning it returns just +//! another reference to the same lock. +//! +//! Furthermore, [`LockGuard`] is not tied to [`Lock`] by a lifetime, so you can keep guards for +//! as long as you want. This is useful when you want to spawn a task and move a guard into its +//! future. +//! +//! # Examples +//! +//! ``` +//! # smol::run(async { +//! use async_lock::Lock; +//! use smol::Task; +//! +//! let lock = Lock::new(0); +//! let mut tasks = vec![]; +//! +//! for _ in 0..10 { +//! let lock = lock.clone(); +//! tasks.push(Task::spawn(async move { *lock.lock().await += 1 })); +//! } +//! +//! for task in tasks { +//! task.await; +//! } +//! assert_eq!(*lock.lock().await, 10); +//! # }) +//! ``` + +#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)] + +use std::cell::UnsafeCell; +use std::fmt; +use std::ops::{Deref, DerefMut}; +use std::sync::atomic::{AtomicBool, Ordering}; +use std::sync::Arc; + +use event_listener::Event; + +/// An async lock. +pub struct Lock(Arc>); + +impl Clone for Lock { + fn clone(&self) -> Lock { + Lock(self.0.clone()) + } +} + +/// Data inside [`Lock`]. +struct Inner { + /// Set to `true` when the lock is acquired by a [`LockGuard`]. + locked: AtomicBool, + + /// Lock operations waiting for the lock to be released. + lock_ops: Event, + + /// The value inside the lock. + data: UnsafeCell, +} + +unsafe impl Send for Lock {} +unsafe impl Sync for Lock {} + +impl Lock { + /// Creates a new async lock. + /// + /// # Examples + /// + /// ``` + /// use async_lock::Lock; + /// + /// let lock = Lock::new(0); + /// ``` + pub fn new(data: T) -> Lock { + Lock(Arc::new(Inner { + locked: AtomicBool::new(false), + lock_ops: Event::new(), + data: UnsafeCell::new(data), + })) + } + + /// Acquires the lock. + /// + /// Returns a guard that releases the lock when dropped. + /// + /// # Examples + /// + /// ``` + /// # smol::block_on(async { + /// use async_lock::Lock; + /// + /// let lock = Lock::new(10); + /// let guard = lock.lock().await; + /// assert_eq!(*guard, 10); + /// # }) + /// ``` + pub async fn lock(&self) -> LockGuard { + loop { + // Try acquiring the lock. + if let Some(guard) = self.try_lock() { + return guard; + } + + // Start watching for notifications and try locking again. + let listener = self.0.lock_ops.listen(); + if let Some(guard) = self.try_lock() { + return guard; + } + listener.await; + } + } + + /// Attempts to acquire the lock. + /// + /// If the lock could not be acquired at this time, then [`None`] is returned. Otherwise, a + /// guard is returned that releases the lock when dropped. + /// + /// # Examples + /// + /// ``` + /// use async_lock::Lock; + /// + /// let lock = Lock::new(10); + /// if let Some(guard) = lock.try_lock() { + /// assert_eq!(*guard, 10); + /// } + /// # ; + /// ``` + #[inline] + pub fn try_lock(&self) -> Option> { + if !self + .0 + .locked + .compare_and_swap(false, true, Ordering::Acquire) + { + Some(LockGuard(self.0.clone())) + } else { + None + } + } +} + +impl fmt::Debug for Lock { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + struct Locked; + impl fmt::Debug for Locked { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str("") + } + } + + match self.try_lock() { + None => f.debug_struct("Lock").field("data", &Locked).finish(), + Some(guard) => f.debug_struct("Lock").field("data", &&*guard).finish(), + } + } +} + +impl From for Lock { + fn from(val: T) -> Lock { + Lock::new(val) + } +} + +impl Default for Lock { + fn default() -> Lock { + Lock::new(Default::default()) + } +} + +/// A guard that releases the lock when dropped. +pub struct LockGuard(Arc>); + +unsafe impl Send for LockGuard {} +unsafe impl Sync for LockGuard {} + +impl Drop for LockGuard { + fn drop(&mut self) { + self.0.locked.store(false, Ordering::Release); + self.0.lock_ops.notify_one(); + } +} + +impl fmt::Debug for LockGuard { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(&**self, f) + } +} + +impl fmt::Display for LockGuard { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +impl Deref for LockGuard { + type Target = T; + + fn deref(&self) -> &T { + unsafe { &*self.0.data.get() } + } +} + +impl DerefMut for LockGuard { + fn deref_mut(&mut self) -> &mut T { + unsafe { &mut *self.0.data.get() } + } +}