Crate spin

This crate provides spin-based versions of the primitives in std::sync and std::lazy. Because synchronization is done through spinning, the primitives are suitable for use in no_std environments.

Features

• Mutex, RwLock, Once/SyncOnceCell, and SyncLazy equivalents

• Support for no_std environments

• lock_api compatibility

• Upgradeable RwLock guards

• Guards can be sent and shared between threads

• Guard leaking

• Ticket locks

• Different strategies for dealing with contention

Relationship with std::sync

While spin is not a drop-in replacement for std::sync (and should not be considered as such) an effort is made to keep this crate reasonably consistent with std::sync.

Many of the types defined in this crate have ‘additional capabilities’ when compared to std::sync:

• Because spinning does not depend on the thread-driven model of std::sync, guards (MutexGuard, RwLockReadGuard, RwLockWriteGuard, etc.) may be sent and shared between threads.

• RwLockUpgradableGuard supports being upgraded into a RwLockWriteGuard.

• Guards support leaking.

• Once owns the value returned by its call_once initializer.

• RwLock supports counting readers and writers.

Conversely, the types in this crate do not have some of the features std::sync has:

• Locks do not track panic poisoning.

Feature flags

The crate comes with a few feature flags that you may wish to use.

• lock_api enables support for lock_api

• ticket_mutex uses a ticket lock for the implementation of Mutex

• fair_mutex enables a fairer implementation of Mutex that uses eventual fairness to avoid starvation

• std enables support for thread yielding instead of spinning

• portable-atomic enables usage of the portable-atomic crate to support platforms without native atomic operations (Cortex-M0, etc.). See the documentation for the portable-atomic crate for more information with some requirements for no-std build: https://github.com/taiki-e/portable-atomic#optional-features

Re-exports

pub use mutex::MutexGuard;mutex

pub use relax::Yield;std

pub use relax::RelaxStrategy;

pub use relax::Spin;

pub use rwlock::RwLockReadGuard;rwlock

Modules

barrierbarrier

Synchronization primitive allowing multiple threads to synchronize the beginning of some computation.

lazylazy

Synchronization primitives for lazy evaluation.

lock_apilock_api

Spin synchronisation primitives, but compatible with lock_api.

mutexmutex

Locks that have the same behaviour as a mutex.

onceonce

Synchronization primitives for one-time evaluation.

relax

Strategies that determine the behaviour of locks when encountering contention.

rwlockrwlock

A lock that provides data access to either one writer or many readers.

Type Aliases

Barrierbarrier

A primitive that synchronizes the execution of multiple threads. See barrier::Barrier for documentation.

Lazylazy

A value which is initialized on the first access. See lazy::Lazy for documentation.

Mutexmutex

A primitive that synchronizes the execution of multiple threads. See mutex::Mutex for documentation.

Onceonce

A primitive that provides lazy one-time initialization. See once::Once for documentation.

RwLockrwlock

A lock that provides data access to either one writer or many readers. See rwlock::RwLock for documentation.

RwLockUpgradableGuardrwlock

A guard that provides immutable data access but can be upgraded to RwLockWriteGuard. See rwlock::RwLockUpgradableGuard for documentation.

RwLockWriteGuardrwlock

A guard that provides mutable data access. See rwlock::RwLockWriteGuard for documentation.