commit | 9420c929ee8f4902a758568d5b4915d681bab9cd | [log] [tgz] |
---|---|---|
author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Apr 15 03:06:31 2022 +0000 |
committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | Fri Apr 15 03:06:31 2022 +0000 |
tree | b619093c261ac042480332cde19ac9635c2f1676 | |
parent | a0b4c6f95336547845c690398e237152dfcc9b8d [diff] | |
parent | 7a244b5e4fee3972be8dedc59545cd85b80ef1a7 [diff] |
Snap for 8458224 from 7a244b5e4fee3972be8dedc59545cd85b80ef1a7 to tm-qpr1-release Change-Id: Ia6b1d4792f7ff4b83715dd2d94882b93b756c119
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
, Once
, Lazy
and Barrier
equivalentsno_std
environmentslock_api
compatibilityRwLock
guardsInclude 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 mutex will become available again.
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..100 { *counter.lock() += 1; } } }); for _ in 0..100 { *counter.lock() += 1; } thread.join().unwrap(); assert_eq!(*counter.lock(), 200); }
The crate comes with a few feature flags that you may wish to use.
mutex
enables the Mutex
type.
spin_mutex
enables the SpinMutex
type.
ticket_mutex
enables the TicketMutex
type.
use_ticket_mutex
switches to a ticket lock for the implementation of Mutex
. This is recommended only on targets for which ordinary spinning locks perform very badly because it will change the implementation used by other crates that depend on spin
.
rwlock
enables the RwLock
type.
once
enables the Once
type.
lazy
enables the Lazy
type.
barrier
enables the Barrier
type.
lock_api
enables support for lock_api
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:
Many of the feature flags listed above are enabled by default. If you're writing a library, we recommend disabling those that you don't use to avoid increasing compilation time for your crate's users. You can do this like so:
[dependencies] spin = { version = "x.y", default-features = false, features = [...] }
spin
is distributed under the MIT License, (See LICENSE
).