commit | 1b71a85fdd1b1026c025ebb1e33e40cc9b5fcea2 | [log] [tgz] |
---|---|---|
author | Bob Badour <bbadour@google.com> | Fri Feb 12 21:07:34 2021 -0800 |
committer | Bob Badour <bbadour@google.com> | Fri Feb 12 21:07:34 2021 -0800 |
tree | d8a2e2d2196d95bc2fa75aa909e0a877760fdb7d | |
parent | 80d30c6eaf70bcddf9167f1d4db1342442e0587a [diff] |
[LSC] Add LOCAL_LICENSE_KINDS to external/rust/crates/spin Added SPDX-license-identifier-Apache-2.0 SPDX-license-identifier-MIT to: Android.bp Bug: 68860345 Bug: 151177513 Bug: 151953481 Test: m all Exempt-From-Owner-Approval: janitorial work Change-Id: Ie06f0743924c09c4bb6b044ec24f8ed136c7cb5b
Spin-based synchronization primitives.
This crate provides spin-based versions of the primitives in std::sync
. Because synchronization is done through spinning, the primitives are suitable for use in no_std
environments.
Before deciding to use spin
, we recommend reading this superb blog post by @matklad that discusses the pros and cons of spinlocks. If you have access to std
, it's likely that the primitives in std::sync
will serve you better except in very specific circumstances.
Mutex
, RwLock
and Once
equivalentsno_std
environmentslock_api
compatibilityRwLock
guardsstd
feature to enable yield to the OS scheduler in busy loopsMutex
can become a ticket lockInclude the following under the [dependencies]
section in your Cargo.toml
file.
spin = "x.y"
When calling lock
on a Mutex
you will get a guard value that provides access to the data. When this guard is dropped, the lock will be unlocked.
extern crate spin; use std::{sync::Arc, thread}; fn main() { let counter = Arc::new(spin::Mutex::new(0)); let thread = thread::spawn({ let counter = counter.clone(); move || { for _ in 0..10 { *counter.lock() += 1; } } }); for _ in 0..10 { *counter.lock() += 1; } thread.join().unwrap(); assert_eq!(*counter.lock(), 20); }
The crate comes with a few feature flags that you may wish to use.
lock_api
enabled support for lock_api
ticket_mutex
uses a ticket lock for the implementation of Mutex
std
enables support for thread yielding instead of spinning
It is often desirable to have a lock shared between threads. Wrapping the lock in an std::sync::Arc
is route through which this might be achieved.
Locks provide zero-overhead access to their data when accessed through a mutable reference by using their get_mut
methods.
The behaviour of these lock is similar to their namesakes in std::sync
. they differ on the following:
spin
is distributed under the MIT License, (See LICENSE
).